environmental assessment of mercury pollution in two artisanal gold
TRANSCRIPT
technical report for partnership africa canada’s just gold project
BUTUZI , SOUTH KIVU SOME, ITURI
Environmental assessment of mercury pollution in two artisanal gold mining sites in eastern Democratic Republic of the Congo
First published in November 2016 by the United Nations Environment Programme© 2016, United Nations Environment ProgrammeUnited Nations Environment ProgrammeP.O. Box 30552, Nairobi, KENYATel: +254 (0)20 762 1234Fax: +254 (0)20 762 3927E-mail: [email protected]: http://web.unep.org/
This publication may be reproduced in whole or in part and in any form for educational or non-profit purposes without special permission from the copyright holder provided acknowledgement of the source is made. No use of this publication may be made for resale or for any other commercial purpose whatsoever without prior permission in writing from UN Environment. The contents of this volume do not necessarily reflect the views of UN Environment, or contributory organizations. The designations employed and the presentations do not imply the expressions of any opinion whatsoever on the part of UN Environment or contributory organizations concerning the legal status of any country, territory, city or area or its authority, or concerning the delimitation of its frontiers or boundaries.
Cover Image: A piece of ‘sponge’ gold produced on burning of mercury-gold amalgam
Photo Credits: 3,4,5,7,8,15,16,17,18, 19,21,33,34 © Paul Cordy
Cover photo, Front Inset, 1,2,6,9,10,11,12,13,14,20,22,23,24,25,26,27,28,29,30,31,32,35,36,37,38, Back Inset © Hassan Partow/UN Environment
All the photos in this report were taken in Butuzi, South Kivu and Some, Ituri, except for photos 14 and 19 which were taken in Mongbwalu, Ituri.
Design and layout: Antonia Mendes and Cristina Poiata
Artisanal gold mining is degrading landscapes in eastern Democratic Republic of Congo
TechnicalReportforPartnershipAfricaCanada’sJustGoldProject
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AcknowledgementsThisreportwaspreparedbyPaulCordybasedonfieldworkcarriedoutineasternDRCin2016.The
studywas coordinated by Hassan Partow (UNEP/Post-Conflict andDisasterManagement Branch),
whoalsocontributedsubstantiveinputsandeditedthereport.
Fieldworkwas carriedout in collaborationwith theMinistryof Environment,NatureConservation
andSustainableDevelopment(MECNDD),theCongoleseEnvironmentAgency(ACE),theMinistryof
Mines (SAESCAM) and in consultation with local authorities and mining cooperatives. Sample
analysiswasconductedbySpiezLaboratoryinSwitzerland.PartnershipAfricaCanada(PAC),theUN
peacekeepingmission inDRC (MONUSCO)and theUNDevelopmentProgramme (UNDP)provided
logisticalsupportforthefieldwork.
Specialthanksareextendedtothefollowingpersonsfortheirassistanceinfacilitatingthefieldwork
including:DanielRuiz,M'handLadjouzi,RosemaryKioni,AlainMulimbi(MONUSCO);JamieGraves,
Zacharie Bulakali (Partnership Africa Canada); Félicitér Kabonwa, Michel Bagalwa (Kaziba Local
Authority);MuhsoshereGanywamulume(KazicomCooperative);ClaudiaKamanji(UNEP);andJosef
Debeus(UNDP).
UNEP would also like to extend its sincere appreciation to Spiez Laboratory for carrying out the
laboratory sample analysis including in particularMario Burger,Marc Stauffer, JasminOssola and
AndréPignolet.
UNEPwouldliketoacknowledgethepersonswhoreviewedthereportincluding:JeanClaudeEmene
Elenga,PapyMola(AgenceCongolaisede l’Environnement);JoanneLebert,ZuziaDanielski,Gerard
vanderBurg (PartnershipAfricaCanada); LudovicBernaudat,KennethDavis (UNEPChemicalsand
Waste Branch); Muralee Thummarukudy, David Jensen, Pauliina Upla, Andrew Morton, Sophie
Brown(UNEPPost-ConflictandDisasterManagementBranch);andUsmanTariq(UNITARChemicals
andWasteManagement Programme). Sincere thanks to AntoniaMendes and Cristina Poiata for
finalizingthereportlayoutandpublication.
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
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Tableofcontents
Summary..............................................................................................................................................4
1. Introduction..................................................................................................................................8
Artisanalgoldmining...........................................................................................................................9
GoldminingineasternDRC...............................................................................................................14
ButuziAGMsite,SouthKivu...............................................................................................................14
SomeAGMsite,Ituri..........................................................................................................................24
2. Mercuryassessmentmethods....................................................................................................30
Sedimentsampling.............................................................................................................................30
Dustsampling.....................................................................................................................................31
Mercuryinventory.............................................................................................................................32
3. Analysisresults...........................................................................................................................34
Sedimentanalysis...............................................................................................................................38
Dustanalysis.......................................................................................................................................38
Mercuryinventory..............................................................................................................................38
4. Mercuryreduction......................................................................................................................40
Actionplanformercuryreduction.....................................................................................................42
5. Butuzi:Slopestabilizationandriskmitigation.............................................................................44
6. Some:Forestdegradationandbiodiversityloss..........................................................................50
7. Miningexploration.....................................................................................................................54
8. Occupationalsafety....................................................................................................................56
9. Barrierstoformality,andtheartisanalminingpovertytrap........................................................58
10.Conclusionsandrecommendations.............................................................................................61
Appendix1:Laboratoryanalysesinterpretation.................................................................................63
Appendix2:Laboratoryanalysesresults.............................................................................................69
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SummaryThisreportisanenvironmentalassessmentofmercurypollutionintwoartisanalgoldmining(AGM)
sitesintheeasternDemocraticRepublicoftheCongo(DRC).ItwasconductedbytheUnitedNations
Environment Programme (UNEP) based on fieldwork in Butuzi, South Kivu and Some, Ituri. The
purpose of this assessment is to provide technical advice to Partnership Africa Canada’s (PAC)
pioneering ‘JustGold’project,whichaimstobring legal,conflict-free,andtraceablegold fromthe
two aforementioned artisanal mine sites to international markets. In this respect, technical
assistanceonmercuryreductionresultinginincreasedgoldproductionisalsoanintegralcomponent
oftheincentive-basedmodelthatPAC’sprojectaimstodeveloptoencourageartisanalproducersto
selltheirgoldthroughlegalchannels.
This study represents the first field assessment of mercury use, emissions and releases to the
environment by the artisanal goldmining sector in the DRC. Themethodology for preparing the
inventoryofemissionsand releasesat the twoartisanal goldmining sites complieswithguidance
developedby theUNEPGlobalMercuryPartnership for theMinamataConventiononMercury. In
particular, thebaselineestimates fromthis studyshouldhelp informthepreparationof theDRC’s
Minamata Initial Assessment (MIA) and National Action Plan on Artisanal and Small Scale Gold
Mining (NAP)1. In addition, the report addresses other environmental problems and associated
healthandoccupationalrisksatthetwoaforementionedAGMsites,aswellassomeofthebroader
governancechallengesfacingtheartisanalgoldminingsector.
In addressing themultiple environmental challenges at the twoAGM sites, a progressive strategy
taking intoaccount investmentcostsand thecomplexityofmeasures isproposed. It comprisesof
targetedtechnicalinterventionsto:
i)reducemercuryuseandpollution;
ii)helpmitigateslopedestabilization,deforestationandbiodiversityloss;and
iii)improveoccupationalsafetyintheminingsites.
1TheDRCMIA-NAPwillbeimplementedwithtechnicalassistancefromUNEPandUNITAR,andfinancialsupportfromtheGlobalEnvironmentFacility.Projectactivitiesareplannedtostartinend2016.
SnapshotofArtisanalGoldMiningineasternDRC
Ø 80%ofallartisanalminersineasternDRCdigforgold
Ø Anestimated160,000-200,000goldminers
Ø ~1,000AGMsitesineasternDRC(IPIS:857;BGR:1305)
Ø AGMproductionestimatedat8-10tonnesperannum
Ø Officialexportsaround~200Kgs(i.e.98%smuggled)
Ø GoldisthemainresourcefinancingarmedandcriminalgroupsineasternDRC,accountingfor50%of
profits
Source:IPIS(2015):MappingConflictMineralsinEasternDRC;UNEP-MONUSCO-OSESG(2015);Experts’backgroundreportonillegal
exploitationandtradeinnaturalresources
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
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MercurypollutionMercury use by artisanal goldminers iswidespread in easternDRC, and there is little knowledge
amongusersaboutthetoxicityandenvironmentalhazardsitcanproduce.Extensiveuseofmercury
stems from its quick, easy and effective separation of gold from the ore. Significant mercury
concentrations can be found in soil and rivers near mine sites, as well as inside homes and
businesseswheremercury is burned. The greatest health risk forminers,women, and children is
fromopenamalgamburninginsmallcommunitiesandkitchens,aswellasinurbancentres.
Fewof thoseencounteredduring the fieldassessment (miners, governmentofficials, goldbuyers)
seemedtohavepreviousawarenessofthehealthdangersofmercury.Moreover,noonewasaware
that gold buyers in cities releasemercurywhen smelting andpurifying the gold.Mercury is likely
evaporatedwhenthespongegoldismeltedintoingots.
Atmosphericmercuryemissionsmakeup29%of total releases frombothAGMsites.Mostof the
mercuryusedislostintheminewastes(71%),andpotentiallyuptohalfofthatmaybecarriedby
run-offwiththesuspendedsediments.Theresultingmercurycontaminationmaynegativelyimpact
fluvialbiotaformanykilometresdownstreamofsiteswherewastedischargesintostreams.
Laboratoryanalysisconfirmedthepresenceofmercury ineverycontext inwhich itwasexpected,though concentrations are relatively low compared to artisanal mining communities in othercountries inAsiaandSouthAmerica.This reflects the fact that localminersdonotburnamalgamindoors, nor usemercury in excessive amounts of the gold they can recover. Artisanalmining ineasternCongocreatesavast,dispersed,lowgradewebofmercurycontaminationandmethylationhotspots.Thiscanimpactthelongtermhealthofecosystemsandpeopleacrossbroadswathesofpoor, ruralareas. Inaddition,arsenicconcentrations10to20 foldaboverecommendedstandardsweredetecteddownstreamoftheButuziminingsites,whichcancauseserioushealthproblems.
Table1:AveragevaluesformercuryinventorymeasurementsinButuziandSome.
Inventorymeasurement AverageN=11
Standarddeviation
Mercuryapplied 4.09g 3.98
Amalgam 0.50g 0.42
RecoveredMercury 3.62g 3.73
Goldsponge 0.23g 0.19
Mercurylost 1.00g 1.14
Mercury:Gold 4.3:1 2.74
%losttoair 29 0.10
%losttoland 71 0.10
Apositivefindingisthatsomeminersproducerelativelymodestandconfinedmercuryreleasesby
concentratingthegoldintheiroreusingsimplesluicesbeforeapplyingmercury.Thisrelativelygood
practice, however, is typically offset by the large quantities of tailings and primary material
processed usingwhole ore amalgamation (inwhichmercury is applied to all of the primary ore).
Preliminary mercury inventories of the sites suggest that the ratio of mercury losses to gold
produced lies in the range between 2:1 and 7:1 (averaging 4.5:1), which is consistent with
assessmentsofotherAfricanartisanalminingsiteswithsimilarworkpractices.Thisratioofmercury
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to gold use is high and inefficient by international standards but low in comparison with more
mechanizedpracticesintheAmericasandAsia.
ActionplanforreducingmercuryemissionsArtisanalmining sites shouldbeorganizedso thatallmineralprocessing,mercuryuseand tailings
storageoccur1km (or at least500m)away fromall naturalwater sources, villages,markets, and
restaurants.Thesitemustbeonhighgroundtopreventinundationandalldrainagefromthearea
must go through settling ponds to reduce suspended sediment emissions. The process of
amalgamationofreprocessedtailingsmustbereplacedbybetterprimaryprocessingoforesothat
allrecoverablegoldthatcanbeconcentratedoramalgamatedisextractedinthefirstpass.Further
recommendations for testing include using a blue bowl gold concentrator to process tailings and
recovermercuryandgold,andvaryingthesluicewaterflowrate,amongothers.
Mercuryusecanbegreatlyreducedoreliminatedcompletelybychanginghowtheoreisprocessed.
Thestrategyshouldbetoprioritizeincreasingpre-concentrationbeforeamalgamating.Efficientpre-
concentrationincursgoldlosses,soprocessinginallpartsofthechainneedstobeimproved,from
explorationandplanningofdepositextractionandmineworkings,choiceandpre-processingofore,
efficient grinding for gold liberation, as well as concentration andmonitoring of gold in ore and
waste.Overall,highergoldrecoverycanbeachievedwithoutmercury.Technologyandtrainingare
thesolution,assumingnotonlyformalitybutaccesstoinvestmentandservices.
Aprogressiveplanofactiontoreducemercuryuseandpollutionisproposedbelow.Theplanstarts
with changes requiring the least investment and training, followed by progressively costlier and
more complex changes that can be added when the miners are ready to take the next step2.
Consultationswithminersandlocalcommunitieswillneedtobeorganizedtoobtaintheirviewsand
buy-inontheproposedplan.
Immediateaction:
1. Promote use of retorts or fume hoods to recover mercury and reduce exposure and
inhalationoftoxicmercuryvapours.Minersmuststopusingleavesasaretort.
2. Promoteconcentrationanddirectsmeltingasanalternativetowholeoreamalgamation.
3. Improvewater supply andwastemanagement using impermeable reservoirs, refilling old
minepits,andreorganizationofprocessingactivities.Thiswill isolatemercuryreleasesand
reduceinfiltrationofwaterintolandslideinitiationzones.
Mediumtermobjectives:
4. Analyze goldoremineralogy to guide changes inprocessingmethods forbothmilling and
gravityconcentration.
5. Optimize mill feed, speed, duration, and grain size control, also using participatory
controlledtrials(includinginstallationandcomparisonofexistingmillingequipment).
6. Improve existing sluice practices by optimizing flow velocity, feed consistency and
turbulencethroughparticipative,controlledtrialsonsite.
2DetailedinformationandguidanceonthesolutionsoutlinedbelowisgiveninthefollowingUNEPdocument:ReducingMercuryUseinArtisanalandSmall-ScaleGoldMining:APracticalGuide
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
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7. Fieldtestdifferentmechanicalconcentrationdevicesonsite,beginningwithshakertables,
spirals,bluebowls,andjigs,usingshorttermtrialsoflabscaleequipment(whichcanalsobe
usedtofurtherupgradeprimaryconcentratestoenabledirectsmelting).
Longtermgoals:
8. Implementbestpracticewetmillingandconcentrationprocesses.Potentialoptionsinclude
usingtheArtisanalGoldCouncilBurkinaFasomicroscaleprocessingplantasamodel3.
9. Usetrenchingandpanning(basic)andpotentiallyalsomoderngeophysicalinstrumentation
(suchaselectromagneticsurveysorother)tostudygoldreservesandplanminingactivities.
Theaboveplanwillimprovegoldrecoverywhileprogressivelyreducing,andeventuallyeliminating,
mercuryuse.Itappliesequallytohardrockandalluvialminingsites.
OtherenvironmentalissuesInadditiontomercurycontamination,othermajorenvironmentalimpactsatthetwoAGMsitesare
deforestation(Some/Kafiawemaarea),increasedriskoflandslides(Butuzi),andfluvialdegradation.
Inaddressingthesechallenges,asystemsapproachmaybeadoptedtocapitalizeonsupplementary
benefits that could be derived by linking transparency, land use planning, and pollution control,
where feasible. For example, sustainable forest management and timber transparency initiatives
wouldbeanaturalcorollaryactivity,withbenefitstocommunitiesandlocalecosystemsthatcome
fromlanduseplanningandtechnologicaltransformation.
Land use planning in the context of gold production requires basic exploration and ore body
estimationinordertotightlyconstraintheexcavationsandsitetailingsdisposalandcamplocations
with minimal impact and maximum regenerative potential. Combined mine and forest planning
shouldbedirectedtowardoffsettingsocialandfinancialrisksofformalizationandnewproduction
technologies. Addressing these problems in isolation would ultimately overlook important
unanticipatedconsequencesandmisspotential leveragepoints.Forexample, itwouldnotbewise
orsustainabletosolelyfocusondivertinggoldwealthfromarmedgroupswithoutconsiderationof
the rapid irremediable devastation to large patches of contiguous Central African equatorial
rainforest.Neitherisitpossibletoignorethepossibledeathsandinjuriesofhundredsofpeoplein
landslides and catastrophic flooding induced by uncontrolledmountain slope destabilization from
artisanalmining.ThesethreatsriskreputationaldamagetoPAC’spioneeringpilotprojectandmay
undermine its impact. It is therefore important to establish a risk mitigation plan demonstrating
proactive mitigation actions will be taken. In the Butuzi case, a number of simple measures are
recommendedthatcoulddiminishslopedestabilizationandexposureofpeopletothehazardarea,
butthethreatwillremain.
3SeeAGCBurkinaFasoUpdatereportandvideofilmEmploiel‘OrArtisanalpourl’AideauDéveloppement.
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1. IntroductionThisreportisanenvironmentalassessmentofmercurypollutionintwoartisanalgoldmining(AGM)
sitesintheeasternDemocraticRepublicoftheCongo(DRC).ItwasconductedbytheUnitedNations
EnvironmentProgramme(UNEP)basedonfieldwork inButuzi,SouthKivu(11-15March2016)and
Some, Ituri (18-22 March 2016). The specific purpose of this assessment is to provide technical
adviceandsupporttoPartnershipAfricaCanada4(PAC)intheimplementationofitspioneering‘Just
Gold’ project, which aims to bring legal, conflict-free, and traceable gold from the two
aforementionedartisanalminesitestointernationalmarkets.
Theprimaryfocusofthisstudyisonassessingmercuryuseandreleasesintotheenvironmentand
theidentificationofcontaminatedhotspots.Forthispurposearapidmercuryinventoryinthetwo
AGMsiteswascarriedoutbasedonguidancedevelopedbytheUNEPGlobalMercuryPartnership
for the Minamata Convention on Mercury; namely the Minamata Initial Assessment (MIA) and
National Action Plan on Artisanal and Small Scale Gold Mining (NAP). Environmental samples
(soil/sedimentanddust)werecollectedandshippedtoSpiezLaboratoryinSwitzerlandforanalysis.
In addition, the report addresses other environmental problems and associated health and
occupationalrisksatthetwoaforementionedAGMsites,aswellassomeofthebroadergovernance
challengesfacingtheartisanalgoldminingsector.
In addressing themultiple environmental challenges at the twoAGM sites, a progressive strategy
takingintoaccountinvestmentcostsandthecomplexityofmeasuresisproposed.Itiscomprisedof
targetedtechnicalinterventionsto:
i)reducemercuryuseandpollution;
ii)helpmitigateslopedestabilization,deforestationandbiodiversityloss;and
iii)improveoccupationalsafetyintheminingsites.
Furthermore, it is importanttoemphasizethatreducingandeliminatingmercuryuse isnotonlya
health and environmental protection measure. As technological improvements for mercury
reduction leads to increased gold yields, it is also an integral component of the incentive-based
modelthattheJustGoldprojectaimstodeveloptoencourageartisanalproducerstoselltheirgold
through legalchannels.Awarenessraising includingpracticaldemonstrationtrials isequallycritical
forpromotingmercuryreductionmeasuresandtheiradoptionbyartisanalminers.
The technical assistance provided in this report is part of a collaboration between PAC, the UN
peacekeepingmissionintheDRC,MONUSCO,andUNEPtosupporttheformalizationoftheartisanal
goldminingsectorbyhelpingcontroltheextractionandtradeingold.
4PartnershipAfricaCanadaisfocusedondevelopinginnovativeapproachestostrengthennaturalresourcegovernanceinconflict-affectedandhigh riskareas.PAC isanofficialpartnerorganizationof the InternationalConferenceof theGreatLakes Region (ICGLR), and receives funding from a broad range of governments and institutions to address the issueconflictmineralsintheGreatLakesregionofAfrica.
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
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ArtisanalgoldminingArtisanal miners use rudimentary methods to
extract minerals due to lack of access to
appropriateequipmentandresources,causedby
poverty and tenure insecurity. Mining refers to
theextractionofthegoldbearingmaterial(“ore”)
from the ground, which is the most dangerous
andlaboriouspartofaminingoperation.Mineral
processing separates gold from the ore. In hard
rock (ore “lode”) mining, one first has to crush
and grind the rocks to liberate the gold. Alluvial
minersusuallyonlyexcavatetheoreandseparate
the gold as it occursmostly as free nuggets and
dust. Both alluvial and lode gold miners
concentratetheiroretomakeseparationfeasible.
With the right equipment it is often possible to
extractthemajorityoftheliberatedgoldusingacombinationofdifferentconcentrationtoolsthat
progressivelyupgradetheconcentrateandcapturegoldlosses.
Chemical separationusingmercuryor cyanide isoftenapplied togoldconcentrates toextract the
portionofthegoldthatinevitablycannotbeextractedusingconcentrationmethodsalone.Mercury
picks up gold particles as itmixes and filters through the grains of ore, forming an “amalgam”of
roughlyequalpartsmercuryandgold.Theamalgamcanthenbeevaporatedtoleaveonlythegold
behind.Mercury iseasilyrecoveredbypanning,thoughsignificantamountsofmercurywillalways
adhere to the ore. These contaminated wastes (or “tailings”) must be disposed of durably and
isolated from bodies of water. Metallic mercury used by miners is insoluble. Under certain
conditions, however, elemental mercury can be transformed into more toxic methyl-mercury
species that can dispersemore easily and bioaccumulate in the food chain.Mercury in the food
supply(especiallyfish)isthemainmechanismofhumanexposuretomercuryforpeoplenotdirectly
involved in mining. Translucent tea coloured water, typical of tropical environments, is rich in
organic compounds and likely has oxidation-reduction potential (Eh) and pH conditions that are
favourableformethylatingmercury.Miningeffluentsalsotendtocontainfinesuspendedsediments.
The nanostructure of suspended clays consist of stacks of atom thick sheets that provide many
excellentbindingsites formercury,andmaycatalyzetransformation intoreactivespeciesthatare
precursorsinthemethylationprocess.
Manyartisanalminersarenotsufficientlyawareoradeptatgoldconcentration,andinsteadapply
mercury to all of their ore, for example by adding it to grinding or concentration devices. This is
known as whole ore amalgamation, and it is perhaps themost important of the worst practices
identifiedbytheMinamataConventiononMercury.Minerswhoconcentrategoldinasluiceusually
emithalfofthemercurycomparedwiththosewhopracticewholeoreamalgamation,becausemuch
lessmaterialcomesintocontactwithmercury.Promotingmoreefficientminingpracticescanhelp
motivatesuchbehaviouralchanges,astheyproducemoregoldwhileusinglessmercuryornoneat
all.
Photo1:Anamalgamofgoldandmercurybeforeburning
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Mercuryrecyclingisanotherimportantbehaviourchangethatcanreduceemissionsandcosts.Small
mercurydistillationdevicescalled“retorts”condensemercuryvapours thatareemittedwhen the
amalgam is burned, and larger condensers can be built to trap mercury emissions in advanced
refiningsteps.
Map1:MapoftheDemocraticRepublicofCongo,showingthemainfieldsites.GoogleEarthimagery
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
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Map2:SpatialcontextofButuziminesiteanditslocationvis-à-visthemainpopulationcentreofKazibavillage.Google
Earthimagery
Floodplain
Flow
dire
ction
RelicForest
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Map3:OverviewofKaziba/Butuziarea(SouthKivu);samplinglocationsandcodesareexplainedinthemethodologyand
results(Appendix1).GoogleEarthimagery
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
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Map4:Some/Kafiawema(Ituri)areashowingdeforestationpatches;samplinglocationsandcodesareexplainedinthe
methodologyandresults(Appendix1).GoogleEarthimagery
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GoldminingineasternDRCArtisanalgoldmininghasbeenwaxingandwaning ineasternDRCover thepastcentury.The two
artisanal goldmines examined here have only been operational for 10 to 15 years or less,which
reflects the unpredictable, migratory nature of artisanal mining in this region. In terms of
environmental impacts, thesecasesstandoutnotonly for theirmercuryemissionsbutequally for
the landscape disturbance and forest degradation they produce. Nevertheless, it is important to
reduce mercury at these sites to provide a test case for the elimination of mercury use, as the
cumulative emissions of hundreds of such operations across the DRC amounts to a serious
contaminationproblem.Understandingthenatureoftheseoperationsiskeytomodifyingactivities
forthereductionofenvironmentalandhumanhealthrisks.
ButuziAGMsite,SouthKivuTheButuzisiteliesinaruggedhighlandterrainintheMitumbaMountainrangealongthewestern
edgeoftheAlbertineRiftValley.NaturallydominatedbyAfro-montaneforest,theregionhasbeen
almostcompletelydeforestedformanydecades.Administratively,theButuzisiteislocatedinKaziba
Chefferie (Walungu Territory, South Kivu Province),which has an estimated population of around
45,000.Travelling the~55Kmdirt road from theprovincial capitalBukavu toButuzi takesaround
threehoursbyfour-wheeldrivevehicle.
Photo2:ViewofKazibavillagefromthehillsnearButuziAGMsite
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
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ThemaineconomicactivityinKazibaChefferieissubsistenceagriculture(cassava,maize,potatoes,
beans)andtraditionallivestockrearing.Inthepast,cashcropping(coffee,quinquina)waspracticed
but appears to be largely neglected. Woodland plantations (cypress, pine, eucalyptus) are
extensivelygrownfortheproductionofpolesandplanks.AmajorsupplycenterforBukavu,wood
productionreportedlyprovidesthemainsourceofcashincomeforthelocalpopulation.
Butuziartisanalmining
Artisanalminingtakesplaceonthesteepermountainslopesthataretoodifficulttocultivate.Inthe
Butuzisite,miningistakingplacealongthefaceofaverysteepmountainslope(>30°withafallof
~200meters) that runs down into the Luzinizi river valley. The crest of the Butuzi hill reaches an
altitudeofaround2,200metersdroppingtoaround2,000intheLuzinziRiverbelow.Minersthatlive
inKazibahikeuptotheButuziminesiteinunderonehour.
EnteringtheButuzisite,onecanseetheuncontrolleddestabilizationoftheslopesupcloseaswell
as in the middle distance and successive ridges in the background. All have created a massive,
imminent landslide hazard by removing anchoring vegetation, and digging unlined reservoirs as a
water supply.Water ismanually pumped into hand dug open channels and/or hoses usingwash
basins, and this feeds the earthwork ‘sluices’ burrowed on themine face.Water percolating into
joints, fracturesandtheslideplanethroughthewatercollectionpitsandhaphazardlyconstructed
water ditches will further weaken the slope over time. Cracks are evident in adjacent slopes,
suggestingthatactivelandslideinitiationzonesareundertensionandreadytocollapse.Minerssend
bulkdirt(eitherbarrenoramalgamatedtailings)aswellaslargeboulderstumblingdowntheslope,
whichcreateswasteslidesthatundermineslopestabilityinalonglinedowntotheriver.Themines
themselvescreateanotherstabilityproblem,asunmappedminetunnelpassagesriskbotheroding
the slope from within and by cave-ins from unexpected intersection of workings. Not all mine
entrancesarebuttressedasinphoto4,andtheinsideissparselyreinforced,ifatall.
SouthKivuProvince
SurfaceArea:69,130km2
Population(2005estimate):3.9million
ProvincialCapital:Bukavu
Populationdensity:60persons/km2
Agriculture:70%ofprovincialGDP
Artisanalminers:>100,000(85%ingoldmining)
Source:MONUSCO(2015),StratégieProvincialdeStabilisationetPland’ActionpourlaProvincedeSudKivu;PNUD(2009)Provincedu
SudKivu:ProfilRésuméPauvretéetConditionsdeVie;IPIS(2014):AnalysisoftheinteractivemapofartisanalminingareasinEastern
DRCongo
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Photo 3: Butuzimine entrance.Note the grass fringed rain collection pits visible in the far left of the photo, at the top
marginofthedisturbance,andthehosethatbringswaterbygravitytothesluicesbelow.Abovethepersoninredarethree
amalgamationpondsfullofyellowmud.Greyandredwastechutesarevisiblerightofcentre,andlandslidecracksleftof
centre.Theriverbelowisfullofalluvialminerseveryday,allyear
Photos4and5:Rudimentarymineentrancesandtunnelsaresometimesbuttressedbywoodenbeams,butthesesupports
arefewandtunnelsarepronetocollapse.Minerspanoreinshovelstotestthegoldcontentofore
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Photo6:Impreciseweightsusedinlocalgoldmarketsappeartofavourthebuyers
The Butuzi miners are exploiting primary rock deposits, but only work the unconsolidated near
surfacesaprolitedepositswherethegoldhasalreadybeenliberatedandconcentratedbychemical
weathering.Thissuggeststhata largeamount,perhapsthemajority,ofthegoldintheirdeposit is
containedinthehardquartzrichblocksofrockthattheysendrollingdownthehillastheydigfor
goldbearingsand.Minerssearchouttheyellowandredsands inbetweenharderblocksofrocks,
makingcircuitoustunnelsastheychasethehighgradesandsdeeperintothemountain.Thissearch
isdirectedbyperiodicartisanal“assays5”inwhichminerspanasampleoftheoreinashoveltosee
iftheycanseeparticlesofgoldinside.This“assay”isalsousedtodeterminehowmuchmercuryis
tobeapplied.
Butuzi miners that sluice tend to work in larger teams that coordinate the digging, sluice
construction,watermanagement, and concentration amalgamation roles. It is important to study
andunderstandtheseexistingorganizationalstructuressothattheycanbeadaptedandexpanded
toincludenewrolesdemandedbytheimplementationofbestpractices.Asagroup,sluicingminers
pay about 10 US dollars per day for daily water costs (~5000 FC for water and 4000 FC for pipe
rental).
Butuziminers typicallywork6daysperweekallyear long foranaveragedailygoldproductionof
0.5-1 grams. They arepaid between34-37USdollars per gram.However, themethodsofweight
measuringare impreciseand fromspot checkvisits to the local goldmarketappear to favour the
buyer.Thatis,ifthebuyerweighsthegoldas1gram,itinfactmayweighmorethanthat,whichis
one reasonwhy buyers can afford to apparently give nearmarket price for the deflatedweights
determinedbythem.
5Inmining,anassayreferstoaphysicalanalysisofanore,metaloralloy.
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Photo7:Notethewebofcracksinthecoppermineontheadjacentslope,andthegreywasterockdumpslidestretching
halfwayacrosstheriverbed.Sinuouspatternscreatedbywalledchannelsbuiltbythealluvialminerscanalsobemadeout
below
TheLuzinziriverbedbelowthisminesiteiscompletelyalteredbytheaccumulationofminewaste,
inducedlandslidesandtheactionofhundredsofminersthatworkalongtheriverdaily.Theminers
areconstantlyexposedtothelandslidehazardabove.
They also restructure the riverbed to create sluices, basins, and cobble walls that protect
manufacturedchannelsandholdbackwastesandthattheyhavealreadyworked.Thesesandsare
repeatedlyreworkedovertimebecausetheirmethodsareso inefficientthatthere isalwaysmore
goldtoextractinanyminewaste.Periodicfloodsprobablyalsohelptomobilizeandconcentratethe
gold.
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ButuzimineralprocessingButuziminersdonotcrushorgrindtheirore, insteadconcentratingfreegoldfoundinloosesands
inside their tunnels. Some use sluice channels dug out of the slope and lined with banana bark.
Sometimes they also putmercury in the banana bark,which inevitably leads to losses. Individual
minerstendnottousesluices,andinsteadpanconcentratetheirorebyhand.Theymixinmercury
into the whole ore using plastic wash basins in small amalgamation ponds. Eachminer puts one
~50kgricesackoforeintotheplasticbasin,aswellasseveralgramsofmercury,dependingonthe
richnessoftheore.Theamalgamationpondsareunlinedandnotsufficientlycontainedtoprevent
groundwater infiltration or overflow emissions of mercury bearing suspended sediments during
heavyrainsorinundation.
Photo8:Wallandchannelstructureofheavilyworkedriverbed
Wastedischarges fromhardrockmining increeksandrivers,aswellas thedisturbanceofalluvial
miners working in the larger rivers, completely alter the fluvial morphology of areas they work.
Siltationdestroysfluvialecosystems,renderingformerlyfishbearingriversbarrenandeliminatingan
importantsourceoflocalprotein.
Mercuryuseisusuallycontrolledbytheheadofanartisanalminingteam(so-calledPDG,President
Directeur-General, i.e. CEO), who apportions inputs free of cost according to the potential gold
contentintheoreasassessedusingtheirartisanal“assay”methodofpanningasampleoftheorein
asmallgoldpan. ThePDGisusuallyveryconservativeinhisapplicationofmercury, incontrastto
operationsinAsiaandLatinAmericawhichgenerallyapplymercuryfarinexcessofwhatisoptimal,
withthefalseexpectationthatthiswillensuremaximumpossiblerecovery.Minersthenthoroughly
mixthemercuryinwiththeoreorconcentrateusingbarehandsinaplasticwashbasin.Aftermixing,
theoreispannedtograduallyreducethemassoforeinthebasinuntilalmostallisdischargedand
TechnicalReportforPartnershipAfricaCanada’sJustGoldProject
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they can easily recover the liquidmercury. Thismercury is then squeezed through a cloth, taking
caretocatchtheexcessmercuryinthewashbasin.ThatmercuryisreturnedtothePDG.Next,the
resulting amalgam is burnedover a charcoal fire. InButuzi themercury is dispensed fromaneye
dropper,andinSometheyusesmallsyringes.Mostmercuryislosttothetailings,thoughthemost
immediatepublichealthriskresultsfromopenamalgamburning.
Photo9:Openairburningofgoldamalgamwithatablespoononcharcoalstove
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
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Photos10and11:Bananabarkmakesaneffective,ifinefficient,goldconcentrator(left).Propercarpetsandasmooth,10
slopedsluicebedwouldbemoreeffectiveincapturinggold.Plasticwashbasinsmakerelativelypoorgoldconcentrators,
andpropergoldpanswouldbemoreeffective
Photo12:Mercurydropletsvisibleonthebananabark
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Oreextraction
Amalgamation
Sluice
Ore
Sluiceconcentrate
Burning
Tailings
Amalgam
MercuryVapour Gold
Diagram1:FlowdiagramformineralprocessinginButuzi.Sluicesareonlyusedbygroupsofminers.
Independentminersusewholeoreamalgamationeachtimetheyextractonesackofore.
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Photos13and14:ThePDGmanagesthemercuryforthesite,whichishandedoutforfreetominers,andthencollectedin
thesamebottleorsyringeaftertheexcessissqueezedoutoftheamalgam
OntheLuzinziriver,belowButuziandadjacenttoKaziba,sluicesaredugintotheriverbedandlined
withlargerocksonthesidesandbananabarkasaconcentrationmedium.Minersscoopsandsand
gravelsintoshovelsandwashthembydippingthemintothewatercurrentatthetopofthesluice
andthrowingthemintotheairandcatchingthemagainseveraltimesinsuccession.Thisseparates
the finesediments thatcontainthesoughtaftergolddust that isconcentratedas they flowdown
thesluice.Thewashedgravelsaretossedintowastepiles.
Photo15:Repeatedreworkingofsandsrightattheedgeofthevillageagriculturalfields
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SomeAGMsite,IturiSomeislocatedinIturiprovince,inaflatequatorialrainforest(<900meters)whichisstillrelatively
intact but under increasing deforestation pressure. The AGM site is adjacent to one of theDRC’s
most importantprotectedareas,theOkapiWildlifeReserve(OWR),which isalsoaUNESCOWorld
HeritageSitethatisonits‘DangerList’since1997.Situatedwithina25-30kilometredistancefrom
theORW,Somefallswithinthedesignated50-kmbufferzonesurroundingtheentireReserve.
Miners in the Someareaof Ituri province practice amix of alluvial andhard rockmining, though
apparentlyonlythehardrockminersusemercury.Thereisadistinctpossibilitythatalluvialminers
will realize that mercury can also improve alluvial gold production. Therefore, it is important to
monitoralluvialoperationsandprovidethemwithmoreproductivemethodssothattheyhavegood
alternativestomercury.Alluvialminersandhardrockminersleavelargeholesintheforestunfilled
andbarrenofgoodsoil.Thiscreatesapockmarkedlandscapeofstagnantponds,gravellysoils,and
disturbedwatercourses.
Kafiawema,themainSomeareaminesiteinvestigatedinthisstudy,islocated30minutessouthof
Mambasa,mostly on good dirt roads. Although there is aminer’s camp located at themine site,
manyminers live innearbySome,which is about30minutesawayon foot.Mostof Some’s~400
inhabitantsaredirectlyinvolvedinmining,althoughloggingofhighvaluehardwoods(oftenillegally),
andsomeagriculture(mostlysubsistence)arealsopracticed.
IturiProvince
SurfaceArea:65,658km2
Population(2005estimate):4.2million
Populationdensity:65persons/km2
ProvincialCapital:Bunia
Artisanalmining:almostentirelygold
Artisanalproduction:~2tonnes
Source: SiteOfficielde laProvincede l’Ituri (2016):http://provinceituri.info/; IPIS (2014):Analysisof the interactivemapofartisanal
miningareasinEasternDRCongo
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
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Kafiawemaartisanalmining
Theorebodiesusedby theKafiawemaminersconsistof thick,hard,andcontiguousquartzveins.Thismaterialisbrokenapart,hauledout,andcrushedto“millable”chunks,allbyhand.
In Kafiawema, the family of the present concession holder discovered a gold bearing vein behind
their house, so theentire camp is beingmoved to allowexploitationof thenewvein.Apparently
that person now has legal provincial title to mine aggregate (stones, gravels, sand) at the site.
Seemingly, provincial authorities are using quarrying licenses to also cover gold mines (whose
mandate normally lies with the central government). Moving their camp to expand their mining
operation,meansclear-cuttinganotherpatchofclimaxequatorialrainforest.
Photo16:Openpitminescanonlyoperateas longasthewater ispumpedoutandpitwallsarestabilized.This imposes
limitsonthedepthofexploitation,andexpandstheareathatmustbeclearedtosustainthesamenumberofminersover
time.Pitsaredugwithhandtoolsandwaterisremovedwithgaspoweredpumps
TechnicalReportforPartnershipAfricaCanada’sJustGoldProject
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Kafiawemamineralprocessing
TheminersofKafiawemauseadrymillwith steelballs.Themill andballs arevisiblyworndown.
Thereisnocontroloverthemillspeed,thoughtheycontrolthesizeofmilloutputbyusinga~1mm
sieve.Thisisaroughlyappropriatediscriminatingsizeformostprimaryconcentrationapplications.
Nevertheless,theprecisecontrolsizecanonlybeassessedbyformalgranulometricanalysis.
This is a relatively simple analysis that would normally be conducted during the baseline and
planning stageof aproject. Insteadof returningoversizematerial to themill for further grinding,
miners insteadhand itover to themanual stampmillers.Thesemillersuseametal variantof the
traditionalmortarandpestlemethodforhandpoundingmaniocrootflour.
In Kafiawema, the drymill discharge ismixedwithwater to create a slurry that is fed to a sluice
throughawashbasinwith1-2 cmholes cut into thebottom.This creates a somewhat controlled
flowofmaterialontothesluice.Fortunately,theydonotfirstimpregnatethecarpetswithmercury,
sothisfirststepisnotwholeoreamalgamation.
Photo17:Thisolddieselmotormustregularlybefedfreshoiltokeepitrunning.Thecapacityofminerstoimprovisethis
roughbutfunctionalmilldrivesystem,demonstratestheircapacitytolearntooperatebestpracticesequipment
Next,theresultingamalgamisburnedoveracharcoalfirewithgreenleavescoveringtheamalgam
totrapsomeoftheevaporatedmercury.Mostofthemercuryis lost,butthesmallportioncaught
on the leaves iswashed into thewashbasinandmoremercury is added toabsorb the recovered
mercurymoreeasily.Suboptimalconcentrationtechniqueslikelyresultinverylowgoldrecoveries.
This conclusion is supported by the fact that they can productively rework tailingsmultiple times
(while also, of course, serially reapplying mercury). Miners have no other way to assess their
productivity per unit ore because they do not study the bulk content of primary material (also
knownasthe‘headgrade’).
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
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Theassessmentteamwasunabletoobservethegoldproduction fromsluiceconcentrationof the
orethatisgroundintheballmillinKafiawema,norinventorythemercuryusedintheamalgamation
ofthesluiceconcentrateofthatmaterial.Thisisunfortunate,asitisundoubtedlywheremostofthe
gold is produced, yet the expected amounts were not being sold at the PAC project’s legal gold
buyingshop6.Thereseemedtobemistrustandamistakensuspicion that the realpurposeof this
projectwastobuythegoldandprofitfromexport.Thatopinionwasexpressedexplicitlybyminers
atthecommunityconsultationinButuzi,andprojectstaffindicatedthiswasaperceptionsometimes
foundinSomealso.Ononeoccasionwhenthesluicewasnotbeingused,itwasobservedthatitwas
linedwithamoreoptimalsyntheticsluicecarpetforconcentrationoftheprimaryore,insteadofthe
towels andwoollenmats usedbyothers.When asked about it, the PDG said that they got those
carpetsfromaformalminenearby.Itwouldbeveryusefultoinvestigatethisasapossiblesourceof
bettersluicecarpetslocally,orpotentiallyalocaldistributor.
The“owner”oftheore(inKafiawema,thisisthepersonthatdiscoveredthequartzvein)keepsthe
tailingsaspaymentfortherighttomineandalsofordistributingmercurytotheminersforfree.The
mining tails of all the aforementioned processes are reprocessed 6 or more times using more
mercury each time. All theminers are required to sell their gold to the PDG, who probably also
collectsafractionofitasroyaltiesforthe“owner.”
Photo18:Continuousreprocessingofminetailings.Notethelackoforganizedtailingsstorage,oreffluentcontrol
6PAC’sJustGoldModelTradingHouse(Maisond’achatmodèle)actsasthelegalconduitforartisanallyproducedgoldbypurchasingitatcompetitiveprices,packagingit,andsellinggoldtoapartneredlegalexporter(comptoir).
TechnicalReportforPartnershipAfricaCanada’sJustGoldProject
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Photos19and20:This(left)isprobablyanappropriatemeshsizefortheKafiawemaore(approximately1mm),atleastfor
the primary grind. Granulometric analyses would better indicate the optimal size.Mortar and pestle secondarymilling
(right)
Photo21:InKafiawematheslopeofthissluicecouldbeoptimized,andthetwosluicesectionsshouldbearrangedinLorZ
configurationtoforcetheflowtostopandrestart(mostgoldiscaughtinthefirstmetreofthesluice,makingaturngives
moreeffectivesluicelength
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
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Oreextraction
Mortarandpestlegrinding
BallmillGrinding
Amalgamation
Sluice
ManualCrushing
Ore
+1mm
-1mm
Sluiceconcentrate
Burning
Tailings
Amalgam
MercuryVapour
Gold
Orepowder
+0.15mm
-0.15mm
Diagram2:FlowdiagramformineralprocessinginKafiawema.Sieves(symbolizedbydasheddiagonal
lines)areusedtocontrolthesizeofmaterialthatpassestothesluiceandmanualgrinding.Tailingsare
oftenreprocessed5timesormoretoextractfurthergold.
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2. MercuryassessmentmethodsEvaluationof theamountsand impactsofmercurycontaminationwas throughsite investigations,
communitymeetings,andenvironmentalsampling(sedimentsanddust).Siteinvestigationsincluded
direct measurement of mercury usage and recovery in each stage of mineral processing, which
provides an estimate of the mercury emissions to air and land/water for each gram of gold
recoveredatthesite.
Theassessmentmethodologyincluded:
i) discussions and interviewswith artisanal ‘mining cooperatives’ andminers, gold traders,mining
technical administration and local authorities concerning priority environmental and occupational
safetychallenges;
ii)sitewalkoversurveytoscopeenvironmentalproblems;
iii) inventoryquantifyingmercury inputsand releases,andestimate the ratioofmercury losses to
goldproduced;
iv)collectionofsoil/sedimentanddustsamples.Intotal57sampleswerecollectedfrombothsites
comprising of 29 soil/sediment samples; 26 swab samples and 2 geological samples. All samples
wereshippedtoSpiezLaboratoryinSwitzerlandforanalysis.
In addition in both Butuzi and Some, consultationmeetingswere organizedwith artisanalmining
cooperatives,miners,goldtraders,theMiningMinistryandlocalauthoritiesexplainingthepurpose
of UNEP's environmental assessment, initial findings from the field visits and potential
recommendationsforprogressiveremedialsolutions.Thesemeetingsalsoprovidedanopportunity
to raise awareness and share informationmaterials about the health and environmental risks of
mercuryuseinAGM.
SedimentsamplingSamplingfollowedascloselyaspossibletheProtocolsforEnvironmentalandHealthAssessmentof
Mercury Released by Artisanal and Small-Scale Gold Miners (Veiga and Baker 2004). In general,
samples were collected from least to most contaminated but it was not always feasible to
successfullydefine those zones.Thedisorderlyarrangementofoperations, legacymining impacts,
and upstream operationsmake it difficult to find “pristine” control points. Siteswere chosen for
their potential to accumulatemercury. This included tranquil areas along river banks where fine
sediments accumulate (e.g. on the inside of a meander), amalgamation ponds, and areas of
depositionofminetailingsorsedimentsthathadbeensluicedandamalgamated.
Most samples were of river or amalgamation muds and sands collected from beneath standing
water. Bottle samples were obtained by taking a composite sample of several trowels full of
submergedcreekbedsediment,mostlynearthecreekedgeswherewatereddiedoutanddropped
itsfineload.
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Photo22:Swabsamplingonmarketstallsnexttowhichopenairamalgamburningtakesplace
Eachsampletooksedimentfrom4-6locationsoftheupper10-20cmofsediment,mixinginroughly
equalamountsofdeeperandsurfacesediment.Eachsamplewasmixedinaplasticbag,andmixing
bagswereonlyusedonce,and the trowelwasgivenawayaftereachmine sitevisited toprevent
fieldsamplingcontamination.Oncevisiblyhomogenizedintoauniformcolour,themixwaspoured
into the sampling jar, taking care to take somematerial from the top, middle, and dregs of the
sample mixing bag. Each sample was labelled with the geographic coordinates, sampling time,
sample number, description of the context in relation to the mine site, river or sediment
characteristics and other aspects of the sampling site. The bottles were then sealed tightly and
packagedintwoplasticbagstightlyclosedbytwistingandtying.
DustsamplingDustsamplingwasdonewearingrubberglovestoavoidcontaminationduringhandling,andmarked
withgeographiccoordinates,samplingtime,andadescriptionofthesitebeingsampled.Sampling
focused on finding sites near amalgam burning locations such as in home residences including
kitchens,goldbuyerandsurroundingmarketsstalls,foodkiosksandtreesnearopenburningspots.
Dust collection siteswere always taken from shady locationswhere solar exposurewould not be
able to evaporate the mercury (such as roof beams, under shelves, under eaves, or walls in
permanentshadeorartificiallighting).
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Photo23:Sedimentsamplingfromtheamalgamationponds
MercuryinventoryTheButuzisiteisachallengingplacetodoamercuryinventory.Theminersareoftenusingminute
amounts of mercury (<1g) to recover tiny amounts of gold. The masses involved are near the
effective detection limit of the electronic balance used, which is higher than the manufacturers
statedprecisionof0.01gramsduetodifficultiesinfindinglevelgroundandtheeffectsofwindgusts
(whichproducepressuresinthe0.02-5grange).Turbulentwindeddiespeaklaterinthedaywhen
minersareamalgamatingtheirore.
Tocounterthisinstability,aplasticbagfilledwithsandwaspressedtothegroundandthescalewas
thendrivenintothebaginawaythatitwaslevel.Inthefuture,asmallcircularlevelshouldbeused
tomake sure that the scale is evenlybalanced.A clearplastic coverdomeor a glassbowl should
thenbeplacedoverthescaletoblockthewindwhilerecordingthemass.
Theminers also all tend to amalgamateat around the same time, so following theamalgamation
process of oneminer often precludes finding that of others. Tomakemattersmore complicated,
there is typicallyonemanwhosuppliesallof theminerswithmercury,so thatonecannotsimply
trackthechangingweightofthemercurybottletomeasuretheamountofmercuryrecovered.Once
thismangivesmercurytooneminerheproceedstogivemoretoanother,thentogetthemercury
recoveredfromyetanotherminerandperhapstogivemoremercurytoathirdminer.Thismakesit
difficulttotracktherecoveredmercury.Furthermore,dustanddirtgrainssometimesadheretothe
tinymercurydroplet,whichmay add a relatively significantmass to the recoveredmercury given
howsmalltherecoveredmercurydropletcanbe.
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
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Photo24and25:Mercuryinventoryusinganelectronicbalancetomeasureratioofmercurylosstogoldproduced
As a result, it is sometimes necessary to use a piece of paper to hold the recoveredmercury or
amalgam. Theminer,however,oftenwetsordropsparticlesoforeormudontothispaperwhen
transferringthemercurytothepaper.Thesolutiontothisistotarethebalancewiththepaperonit,
andthentomeasure theemptypaperafterwardtoseethechange inmassduetocontamination
duringmercury/amalgamtransfer.
Unfortunately,ahigherprecisionbalancewouldhaveevenhigherrequirementsforlevellingandis
likelynotpracticalinthiskindoffieldsetting.Also,mercuryisusedandstoredunderwater,soitis
importanttoseparatethewaterbeforemeasuringthemercury.Asoftplasticspongecanbepressed
tothesurfaceofthemercury,whichwilldrawupthewaterbutnotmercury.
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3. AnalysisresultsMercurywasfoundineverycontextinwhichitwasexpected,thoughconcentrationsarerelativelylowcomparedwithartisanalminingcommunitiesinothercountries.Thisreflectsthefactthatlocalminersdonotburnamalgamindoors,norusemercuryfarinexcessoftheamountofgoldtheycanrecover. Artisanal mining in eastern Congo creates a vast, dispersed, low grade web of mercurycontamination and transformationhot spots. This can impact the long termhealth of ecosystemsand people across broad swathes of poor, rural areas.Mercury vapour exposure is amore acuteproblemforminersthemselvesandthoselivingandworkingnearminingrelatedmercuryemissionsin mining camps, villages, and cities. All values are measured in mg/kg (equivalent to ppm). Fullanalytical results are given in the appendices. Normal levels in soil range from 0.05 to 0.08 µg/g(Veiga et al. 2004). As the DRC has not established standards formercury in soil and sediments,samplesareevaluatedagainstCanadianandSwissguidelinevalues.
Table2:SoilandsedimentqualityguidelinevaluesinCanadaandSwitzerland(mg/kg)
Canada Switzerland
Mercury Arsenic Mercury Arsenic
Soil 6.6 12 0.5 Novalueinlegislation
forsoilprotection
Freshwater
sediment
0.17 5.9 0.5 Novalueinlegislation
forsoilprotection
Map5:Kafiawemaminecampdetailshowingmercurysamplingsites.GoogleEarthimagery
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
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Map6:Butuzimercurysamplinglocations.GoogleEarthimagery
Map7and8:Bukavucitycentre,andKatudumarket(Kaziba)samplinglocations.GoogleEarthimagery
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Map9:OverviewmapofMambasa/Kafiawema/Somearea.GoogleEarthimagery
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
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Map10:Mbembesemercurysamplelocationmap,showingoldunfilledalluvialminingpitsontheright.GoogleEarth
imagery
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SedimentanalysisBackgroundsoilconcentrations(0.018–0.34mg/kg)intheKivuregionareelevatedbutwellbelow
international standards. Sediments in the area of the Luzinzi river (0.064 – 0.091 mg/kg) where
Butuziandotherminersdischargeandhundredsofartisanalalluvialminerspracticeamalgamation,
exceed guideline levels downstream of Kaziba town. Natural arsenic released by oxidation of
sulphideminerals inminetailingshas increasedsubstantially.Arsenicconcentrations10or20 fold
above recommended standards in Luzinzi River sedimentswere detected, thus posing a potential
risktopeopledownstream.TheamalgamationpondsattheButuziminesitearerichinmercuryup
to3.6mg/kg)andarsenic (14000mg/kg),whichwillperiodicallyoverflowanddischargedownthe
slopeintotheLuzinzi.
Background concentrations ofmercury in soil, sediment, and rock are low in the Some area and
upstreamof theKafiawemacamp (~0.1mg/kg).Mercury levelsare significantlyenriched inwaste
dumps(upto6mg/kg)andsedimentsimmediatelydownstreamofmines(upto5mg/kg).Orefrom
Kafiawemacontainssignificantamountsofarsenic(upto310mg/kg),whichisliberatedovertimeby
oxidation in waste piles. Each mine site emits tailings and practices amalgamation in or near
freshwater bodies that are slow or stagnant and rich in dissolved organic compounds, thus
promotingthegenerationofreactive,mobile,andbioavailablemercurycomplexes.
DustanalysisSwab sampling shows that mercury concentrations in Katudu market (near the town of Kaziba,
wheremuchoftheButuzigoldissold)increase(from0.2to1.7mg/kg)asoneapproachesthegold
buyerscornerwhereamalgamisopenlyburned,despitethefactthatminersburntheiramalgamat
themine site first. Evidence of dust contamination from open air burning suggests that airborne
mercury concentrations in the market are frequently far in excess of WHO health guidelines (1
microgrampercubicmetre,WHO2003),and is thereforeasignificantrisk forpeopleworkingand
shoppingthere.Nearbystreamsedimentalsocontainmercury (0.3mg/kg), thoughconcentrations
do not exceed guidelines. In Bukavu, swabs of walls near gold shop chimneys (1.2 – 7 mg/kg)
indicatethatspongegoldsoldtherecontainsignificantamountsofmercurywhichcouldbeputting
thousandsofurbanresidentsatrisk.Dustswabstakeninhutswheremercuryisstoredorburned,
andontreesnearamalgamburnsites,werealsofoundtocontainsignificantmercurycontent(2–
1200mg/kg). In hopes of recoveringmercury,miners place green leaves on top of the amalgam
duringburning,andasampleoftheseleavescontainedmorethan2%mercurybydryweight.Tens
ofgramsof leavesascontaminatedasthisareproducedanddiscardedhaphazardly inandaround
miningsitesonadailybasisacrosseasternDRC.
MercuryinventoryAnadequatenumber(5)ofmercurymassbalanceswereundertakenatbothsitestogiveageneral
ideaofmercuryuseandreleaserates,andlocalPACstaffweretrainedtorepeatthemregularly.This
will build up a longer term time series of mercury usage that offers amore reliable estimate of
mercuryreleasesandalsotrackreductionsduetochangesinpractices.Onaverage,minersatboth
sites released more than 4 grams of mercury to the environment for each gram of gold they
produced.One thirdof thatmercurywas emitted as vapour, and the rest is released to landand
water.
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
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Table3:Butuzimercuryinventory(ingrams)
Butuzi Average
Mercuryapplied 0.31 0.72 0.84 0.12 0.50
Amalgam 0.06 0.32 0.14 0.20 0.47 0.31 0.25
Recoveredmercury 0.10 0.10 0.68 0.29
Goldsponge 0.03 0.08 0.11 0.25 0.05 0.10
Mercurylost 0.24 0.94 0.22 0.09 0.22 0.38 0.35
Mercury:Gold 8.00 2.75 0.82 0.88 7.60 4.01
Table4:Somemercuryinventory(ingrams)
Kafiawema Somesite2 Average
Mercuryapplied 6.01 5.88 5.3 12.13 5.47 5.06
Amalgam 0.13 1.22 0.68 0.75 1.2 0.58
Recoveredmercury 5.62 4.04 4.76 11.17 2.5 4.73
goldsponge 0.08 0.56 0.29 0.36 0.46 0.25
Mercurylost 0.44 2.5 0.93 1.35 3.71 1.11
Mercury:Gold 5.50 4.46 3.21 3.75 8.07 4.25
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4. MercuryreductionThefollowingrecommendationsapplytobothAGMsites.Mills7andretortsshouldbeplacedatleast
500metresdownwindofhabitation,foodpreparation,andallnon-miningactivities;andasfaraway
aspossiblefromnaturalbodiesofwater.Themillsiteshouldhaveasluicingpondintowhichsluice
tailingsarecollected,whichdrains intoaseriesofsedimentationpondsthatprogressivelyremove
fine sediments before discharging. A pond approximately ~5 m2 in area should be sufficient, as
tailingsshouldbeperiodicallydugoutandreprocessedorstored.
Themill siteshouldalsohavea longtermtailingsstoragesite that ishigher thanandat least500
metresfromwaterbodies,abovethewatertable,dugoutofironrichclaysoil.Thelocationshould
also be marked with warning signs indicating the presence of mercury and toxic hazard. This
excavation should be lined by iron rich (red) fine clay or a geomembrane to reduce percolation.
Decommissionedmine pits can also be used for tailings storage. Themill site also needs a small
concrete lined amalgamation pond, perhaps with low brick walls to increase the convenience of
panninginit.Onlytheverylaststepofamalgamatingthepannedconcentrateshouldbedoneinthis
pond,thusisolatingallofthepotentialmercuryreleases.
There should be a proper retort and heat source on site, preferably a gas torch rather than the
traditionalcharcoalmethod(thelatterdoesnotproducesufficientheat).Eventuallythereshouldbe
asufficientlyhightemperaturetorchtodirectlysmeltthegolddirectlyinsteadofusingmercury.The
retortshouldbestoredfar fromhousesandrestaurants,andnever inornearpeoples’houses.As
themill, tailings and amalgamation pond are all located right at the edge of themine camp, the
retortiscurrentlykeptrightoutsideminers’residenceswhichisdangerouspractice.
DustexposurereductionThedrymillingmethodsusedatKafiawemapresentasignificantdustcontaminationproblemthat
canproduceshorttermandlongtermhealthproblems.Thereforethemillshouldberelocatedtoa
site far downwind of the mine camp. It would also be beneficial to determine typical prevailing
windsfortheareatoensurethatthemercuryanddustcontaminationisplaceddownwindfromthe
village.
ImprovingmineralprocessingtoeliminatemercuryuseEliminatingmercurycontaminationandincreasinggoldproductionarecompatiblegoals;infactthe
latterisessentialifminersaretomaketheswitchtobetterpractices.Mercuryisthefastest,easiest,
andmostreliablemeanstoseparategoldfromtheore.Bycontrast,gravityconcentration ismore
time consuming, fastidious, and inevitably loses gold in direct proportion to the degree of
concentrationachieved.Tomakeahighgradeconcentrate(gradeistheconcentrationofgoldinthe
concentrate) incurs greater gold losses than ifonewere satisfiedwitha lowergrade concentrate.
Therefore, it is important to reform the entire production chain to improve gold recovery by
leveraging various inefficiencies that are a product of the rudimentary methods used by miners.
Increasing gold production by closing efficiency leaks can offset the losses incurred by generating
higher grade concentrates. This consists of improving milling efficiency (in the case of hard rock
7NotemillingisnotpracticedattheButuzisite,butthismayberelevantinthefutureasminingactivitiesadvance.
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mining)toensurethatgoldparticlesareoptimallyliberatedfromtheore(mechanicallybrokenaway
fromquartzandotherminerals)whilenotgrindingtheseparticlesintoshapesandsizesthatarenot
amenabletogravityconcentration.Furthermore,lossesfromgravityconcentrationcanbereduced
by optimizingmethods according to the nature of the gold itself (size distributions and shapes of
goldgrains)andbydesigningachainofconcentrationtoolsthatupgradeconcentratessequentially
andcapturegoldlossesbyrecyclingandupgradingtailingsofearlierlinksinthechain.
This impliesmorecomplex systemsshouldbe laidout soas to flowconcentratesand tailings into
subsequentstepsattheappropriateandconsistentfeedrates.Onceestablished,thesesystemsalso
require less labour, which can free miners to spend more time actually extracting ore from the
ground.Asaconsequenceitalsoestablishesmoretechnicaltasksthatmustbemanagedbypeople
with a higher degree of training, thereby diversifying the labour market within camps and
encouraging participation in training and skills upgrading. This reformedmineral processing chain
canbebuiltlinkbylink,beginningwiththesimplestmethodsrequiringtheleastcapitalexpenditure
and training. Ideally, the gains in each step canhelp offset the cost of adding further links in the
chain.
Analysis of gold concentrations in their primary ore should be a priority for this project, as it can
show that gold is being lost and that alternatives aremore efficient. It is important to note that
precisedeterminationsofefficiencyaredifficulttoobtainexceptovermanyrepeatsthroughalong
operational period. This averages out variability due to changes in ore grades and statistical
difficulties such as the ‘nugget effect’ that plagues gold ores in particular. Nevertheless, initial
mineralogicalanalysescanstillprovidesufficientevidenceofpotentialefficiencygainstomakeand
justifyfinancialmodelsofprocessingplantsthatsuitagivenore.
Inparticular,thetargetmilledgrainsizeshouldbedeterminedbylaboratoryanalysis,andoversize
materialsscreenedoutandreintroducedtothemillormilledinasecondarymill.Thiswillproduce
the optimal gold liberation without over grinding. Instead of first grinding the oversize material
enoughtopasstheirprimary(~1mm)sieve,Kafiawemaminersgrindtheoversizematerialtoamuch
finermeshsize(~<0.1mm;probablytoofine).Thisresultsingoldlossesduetothefactthatthegold
ishammeredtooflatforefficientsluiceconcentrationandtoofineforamalgamation.Theyusethe
samemortarandpestlestampmillingtechniqueusedtopreparefood,andsievetheresultwitha
very finemesh to separate the coarse grains for further grinding. Itwould be best tomill all ore
particlesto~1mm(ortotheoptimalsizeoncethissizehasbeendetermined),andthenreprocess
tailingsofthatprocesstoafinersizeoncethegoldhasbeenremoved.Theover-milledmaterial is
also treated using whole ore amalgamation leading to maximum mercury contamination for
minimumgains.Optimizationshouldbedonethroughaseriesofcontrolledexperimentswithlarge
homogenous split ore samples that will enable miners/experimenters to directly compare gold
recoveryofdifferenttrials.Theremayalsobewaystousetheartisanal“assay”thatartisanalminers
are familiar with (in which they hand grind with a hammer and concentrate in a small pan to
evaluate the gold content of the sample) as third party evaluation of the grade of resulting
concentratesormilloutput.
Minersdonotcurrentlyusemagnetstoseparateoutthemagneticcomponentoftheirconcentrate,
andsometimesgrainsofblacksandcouldbeobservedadheringtotheiramalgam.Stirringastrong
magnetcovered inclotharoundinthepanningconcentratecaneliminatea lotoftheblacksands,
thusupgradingtheconcentrateandimprovingamalgamation.Furthermore,thisisanimportantstep
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inpreparingtheconcentratefordirectsmelting(meltingtheconcentratetoseparatethegoldinthe
formofingots).
In summary,mineral processing should be improved by the following actions in each step of the
processingchain:
Crushing: strive for auniformcrush size so thatmillingproceedsuniformly.Amechanical crusher
wouldfreeuplabourforotheractivities.
Milling:Optimizemillspeed,loading(includingratioofgrindingmedium,ore,andwater),useawet
mill,replacewornoutgrindingmedium(steelballs),andoptimizegrindtime.
Concentration: Use proper sluice carpets instead of towels and blankets, use shaker tables, bluebowl concentrators, and panning to upgrade sluice concentrates to the point where they can bedirectlysmelted.
ActionplanformercuryreductionBasedontheabovediscussiononmercuryreduction,astructuredplanofactionisproposedforthe
twoAGMsites.Theplanstartswithchangesrequiringtheleastinvestmentandtraining,followedby
progressivelycostlierandmorecomplexchangesthatcanbeaddedwhentheminersarereadyto
take thenext step.Consultationswithminersand local communitieswill need tobeorganized to
obtaintheirviewsandbuy-inontheproposedplan.(Seealsoflowdiagramformineralprocessingof
thetwosites).
Immediateaction:
1. Promote use of retorts or fume hoods to recover mercury and reduce exposure and
inhalationoftoxicmercuryvapours.Minersmuststopusingleavesasaretort.
2. Promoteconcentrationanddirectsmeltingasanalternativetowholeoreamalgamation.
3. Improvewater supply andwastemanagement using impermeable reservoirs, refilling old
minepits,andreorganizationofprocessingactivities.Thiswill isolatemercuryreleasesand
reduceinfiltrationofwaterintolandslideinitiationzones.
Mediumtermobjectives:
4. Analyze goldoremineralogy to guide changes inprocessingmethods forbothmilling and
gravityconcentration.
5. Optimize mill feed, speed, duration, and grain size control, also using participatory
controlledtrials(includinginstallationandcomparisonofexistingmillingequipment).
6. Improve existing sluice practices by optimizing flow velocity, feed consistency and
turbulencethroughparticipative,controlledtrialsonsite.
7. Fieldtestdifferentmechanicalconcentrationdevicesonsite,beginningwithshakertables,
spirals,bluebowls,andjigs,usingshorttermtrialsoflabscaleequipment(whichcanalsobe
usedtofurtherupgradeprimaryconcentratestoenabledirectsmelting).
Longtermgoals:
8. Implementbestpracticewetmillingandconcentrationprocesses.Potentialoptionsinclude
usingtheArtisanalGoldCouncilBurkinaFasomicroscaleprocessingplantasamodel8.
8SeeAGCBurkinaFasoUpdatereportandvideofilmEmploiel‘OrArtisanalpourl’AideauDéveloppement.
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9. Usetrenchingandpanning(basic)andpotentiallyalsomoderngeophysicalinstrumentation
(suchaselectromagneticsurveysorother)tostudygoldreservesandplanminingactivities.
Photo26:SedimentsamplecollectionfromtheLuzinziriverbedwherealluvialminingistakingplace
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5. Butuzi:SlopestabilizationandriskmitigationSlopestabilityisacomplexproblemandimminentthreat.Largecracksarevisibleinadjacentslopes
to theeastof themainButuzi site indicating that a largedestructive landslide is inevitable. Slope
failurewilldestroyseveralamalgamationponds,mineentrances,andshacksbelowit,andendanger
the lives ofminersworking in the river below. Thiswill likely occur during a heavy and sustained
periodofrainfall,oraftershortburstsofconcentratedrainfall;ahighfrequencyeventinButuziwith
a relatively lowchanceof triggering foranygivenevent.The landslidemayalsobe initiatedbyan
earthquake; near certainty in the unpredictable and low frequency event of large earthquakes
(magnitude4andabove).
Map 11: Massive slope failure induced by artisanal mining at the Butuzi site underscores the risk of a
‘catastrophic’landslidedammingtheLuzinziRiverandcausingdevastatingdownstreamflooding.GoogleEarth
imagery
Miners tend already to avoidworking the site in heavy rains and this should be encouraged and
reinforced. In the event of a massive landslide, it could dam the river below, potentially to a
significantheightbecausethevalleyissteepsidedandtheriverhasonlyanarrowspaceinwhichto
flow.Thetemporarydamthuscreatedwillbuildalargereservoirbehindit,whichmaynecessitate
evacuationof low-lyingareasalongtheLuzinziRiverwherea largeportionofagriculture inKaziba
Chefferietakesplaceandwheresomepeoplehavebuiltpermanenthomes.Itmaytakemonthsfor
thedamtobreach,andthecatastrophicoutwashfloodcouldkillhundredsandeventhousandsof
people if they are not evacuated. A significant area of agricultural fieldsmay bewashed away or
coveredwithdebris,renderingcultivationimpracticalwithoutsignificanteffortstoremoveit.
LuzinziRiver
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Photo27:Cracksvisible inmountainslopes intheupper leftandrightofthispictureareanalarmingsignalof imminent
collapse
Actualmeaningfulreinforcementoftheminesiteusingconventionalengineeringstructuresislikely
prohibitively costly with low probability of success. The rocks are shattered and altered both by
tropicalweatheringandbythegeothermalalterationprocessesthatemplacedthegold inthefirst
place.Insidetheminingtunnels,therockdoesnotappeartobecomeanymoresolid,butratheris
poorly consolidated and deeplyweathered. Not only does this present an extreme risk of tunnel
collapseevenwithoutaseismicevent,butalsoitmeansthattheslopeinstabilityrunstoodeepand
is toopervasive touse rockboltingorotherheavy industrial techniques. In any case, itwouldbe
impracticaltogettheequipmentforsuchengineeringtothisremotesite.
Under these circumstances, disasters are inevitable. Indeed, a landslide last yearwas reported to
have caused several deaths. In fact, injuries or deaths are likely simply from rockfall fromminers
operatingaboveoneanother,asnoonewearshelmetsandthere isnomineplanning.Apparently
theminersaredisposedtoleavingsomeareasalonetodecreaseriskstootherminers,ortoworkin
rotating shifts. In practice this may be hard to agree on or enforce, but should nevertheless be
pursuedaspartofmineplanning.
Bioengineering techniques provide a relatively easy and low-cost option for slope stabilization.
Vetivergrass(Chrysopogonzizanioides)isagoodcandidateforhelpingstabilizethesteepslopesof
the Butuzi mine site. Although classified as a grass, vetiver plants used for land stabilization
purposesbehavemore likefast-growingtreesorshrubs.Theirextensiveandfinelystructuredroot
system can extend 2-3 meters in the first year reaching up to eight meters. While some of the
exposedslopeisbarerockorlooseshaleslopes,therocklayersaregenerallydeeplyweatheredwith
many weak spots through which the vetiver’s fast-growing and deep roots can penetrate. By
plantingthevetiverplantscloselytogetheratcritical locations(e.g.alongthetopofthemineface
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and the footpath), dense hedges can be created to structurally reinforce the slope and also slow
down and spread thewater flow to help control erosion. Finally, it should be noted that there is
goodexpertise in theDRCon vetiver use for slope stabilization anderosion controlwhich canbe
utilizedbytheproject.
Photo28:WatercollectionpitslocatedabovetheButuziminesiteincreaseinfiltrationintolandslideinitiationzones
Controllingdrainage is theothermainmethodwhichcanbeusedtomitigateslope instabilityand
landslidesattheminingsite.Buildingalargeconcretelinedcisternandraincollectionsystemonthe
hill above themine site couldprovide theminerswith a larger andmore reliable sourceof clean
water that would not impact stability and could be fed to the miners using gravity. Ideally, the
cistern shouldbe locatedon theeast faceof theButuzimine summit, at theelevationwhere the
easternapproachtraildescendsintotheminesite,butfarthersouthsothatifitfailsitdrainsaway
fromtheminesite.Fixedtubesshouldconnectthecisterntothetopoftheminesitewherewater
managerscanconnecttoanozzlemanifoldtowhichtheycanconnecttheirhoses.Hand-dugditches
tochannelwatertosluicesshouldbestoppedandreplacedwithlargehoses.
Existingwaterpitsshouldbefilledin,perhapswithmaterialdugouttocreatethenewcistern,and
planted with vetiver and ideally some trees also. If miners, however, are reluctant to stop using
existing water pits, than these should be lined and reinforced with sand bags and terraces and
plantedwithvetiver.Ineithercase,vetiverhedgesandtreesshouldbeplantedalongthetopofthe
entire mine face to soak up and armour against high surface flows of water, and reduce rapid
infiltrationduringstorms.
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Photo29:Hosesaresometimesusedtodeliverwaterforon-siteprocessoperations;amajorchallengeandcostforminers
Apart fromthepresentwatersupply, themainButuzi siteappears tohavenomajorcracks in the
earthwhereunstablelandundertensionispullingawayfromthemountainside.Tarpsmaybelaid
over thecracks in locationswhere this is thecase,with the topmarginof the tarpdugdiagonally
downintothesurfacesoiltocaptureallsurfacerunoffandephemeralstreams.Thebottommargin
ofthetarpsshouldbelinedwithplasticwaterchannelsthatfeedrainwaterstoragecisternslocated
asfarfromthedisturbedslopeasispractical.
Theabovementionedtensioncrackrunoffdiversionwatersystemsandcisternscouldfeedsluicing
and amalgamation stations far away from the disturbed site, thereby reducing the exposure of
miners to slope failurewithoutmaking themhaul their ore uphill. Care should be taken tomake
properly armoured,well drained trails to these safeareas toavoid creatingnew stabilityhazards.
Vetiver and trees should be planted along the trails and around the processing areas to reduce
erosion.
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Photo30and31:Arecentlandslidefollowingheavyrainfalldestroyedseveralminingtunnels
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Another significant geotechnical risk is that the unplanned, unmapped, and haphazard tunnelling
further weakens the slope overall, and presents serious risk of tunnel collapses from miners
burrowing under each other without knowing it. Even without such collapses, the inadequate
buttressingofundergroundworkings (madeworseby thepoorly consolidatedandheterogeneous
hostrock)hasalreadycausedseveralcollapses.Minerspointedoutseveralmineopeningsthathad
collapsed.At leasttwotunnelcollapseshaveclosedoffundergroundaccessessincere-initiationof
operations in 2010. Relatively straightforward measurement and mapping of the existing mine
tunnelscanbemadeusingahipchainandcompass.Bytrackingexcavationprogress,minerscanbe
alerted when they are in danger of compromising each other’s workings.
Photo32:Handdugchannelsareanimportantcauseofslopeinstability
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6. Some:Forestdegradationandbiodiversityloss
BiodiversitylossIn Some, deforestation and biodiversity loss is potentially even a greater environmental concern
thanmercurycontamination.Sinceartisanalmining is takingplace inaprimarytropical rainforest,
with its wealth of biotopes and numerous species, it is important to be mindful of its wider
environmentalfootprint.TheIturiForestisrenownedforitsoutstandinglydiversefloraandfauna.It
is the prime habitat of theOkapi, an endemic forest giraffe that is a national DRC symbol.Other
spectacular and endemic forest species include the bongo, dwarf antelope, forest buffalo, forest
elephant,thegiantforesthog,theaquaticfishinggenet,andchimpanzees.Itisalsoanexceptional
areaforbirds,includingtheendemicCongoPeafowl.
Asnotedearlier,thelocationoftheSomesitewithinthedesignated50-kmbufferzoneoftheOkapi
Wildlife Reserve poses a specific risk. In effect, the Reserve is potentially at the receiving end of
mercurypollution loadsas it liesdownstreamoftheSomesitealongthe IturiRiver.Thiscreatesa
risk of mercury bioaccumulation in the tropical food chain from bacteria to carnivorous fish to
animalsfeedingonfishandfurthertohumans.
Primaryimpactsofartisanalminingonwildlifestemfromhabitatlosscausedbyvegetationremoval
and landdegradation.The resultinghabitat fragmentation is likely todisturb thehome rangeand
migrationpathsofwildlife.Theriskofhuman-wildlifeconflictandthespreadofzoonoticdiseases
increases as animals are displaced and search for new habitats. Miners may also become
opportunistically or deliberately involved in wildlife poaching. In addition, mining camps, which
overtimemaygrowintovillages,arelikelytobecomecentresforbushmeatconsumptionandtrade.
Ivorytrade,whichhasexplodedacrossnorth-easternDRCinthelastseveralyears,isanothermajor
issueofconcern.
The high conservation value of the Ituri rainforest creates a challenging context for the roaming
approachtomininginSome.ThegeneraltrendofencroachingartisanalminingbothwithintheORW
anditsbufferzonefurthercomplicatesthesituation.Moreover,thispressureislikelytocontinueto
increasewiththesteadyimmigrationofpeoplefromthedenselypopulatedhighlands.
DeforestationIn Kafiawema,miners found a gold vein under their mining camp and so they destroyed several
hectares of forest to establish a new camp.Miners in effect clear-cut the forest,whereby all the
treesinthecampareaarecut-downwithonlyasmallnumberoftreesleftstanding.Environmental
impacts of clear-cutting range from soil erosion and increased riskof flooding todepletionof the
carbon sink andmodification of themicro-climate. Remote sensing could be used tomonitor the
evolutionandextentofdeforestationcausedbyartisanalmining.
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Map12and13:SatelliteimagerytakeninApril2013(above)andAugust2015(below)revealexpansionofdeforestation
patchesandalluvialminingpitsintheMbembeseareaoftheSomeminingsite.GoogleEarthimagery
UndisturbedForest
Mbembeseminecamp
Alluvialminingpits
UndisturbedForest
Alluvialminingpits
DeforestationMbembeseminecamp
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Photo33:Ontheedgeoftherapidlyshrinkingclimaxequatorialrainforest,minersslashandburnvaluabletimber
MitigationoflanddegradationSerious legacyproblems frompreviousworkingswere alsoobserved. In the Somearea, extensive
alluvial pits arrayed in a disorderly manner and never refilled dot the landscape. This creates
stagnant ponds that prevent proper forest regeneration and vastly increase the potential for
methylation (and therefore mobilization of more toxic and bioavailable mercury compounds) of
legacy mercury contamination contained within the tailings and pond bottoms left by previous
mining activities and augmented by present mining activities that discharge into these old mine
holes.Whileaddressingthesecomplexenvironmentalissuesisbeyondtheimmediatescopeofthe
‘JustGold’project,asustainableminingmodelneedstoprogressivelydesignawin-winsolutionthat
balances the interestsofminerswith thatof theReserveand its surrounding landscape. It should
also be underlined that in order for remedial measures to gain the buy-in of miners, and be
disseminatedandreplicatedtoothersites,technicalsolutionsproposedmustbeaffordable.
Mitigating measures to address the above mentioned impacts may be promoted through the
project’s agreement with miners on provision of technical assistance. This may include specific
provisionspromoting:
1. Systematic reclamation and backfilling of mined-out pits. Holes containing mercury
contaminated tailings should be covered with one meter of clay or laterite, compacted,
coveredwithsoil,andre-vegetated.
2. Restrictions on wildlife hunting and trade including respecting national regulations on
endangeredspeciesandthehuntingseason.
3. Selectiveapproachtofellingtreesinformedbytechnicalassistanceonmining exploration
andplanning.
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To incentivize miners to gradually implement environmental improvements, the project may
considerofferingan‘environmentalpremium’and/oradditionaltechnicalassistanceforminerswho
demonstrateenvironmentalcompliance.Market-basedinitiativesfor‘greengold’(e.g.Fairtradeand
Fairminedgold)maybeleveragedtohelptheprojectinincentivizingbetterenvironmentalpractice.
Such initiatives should be undertaken in a gender inclusive perspective. Targeted outreach and
follow-upwillalsobenecessarytodriveminerstowardenvironmentalimprovementsovertheshort
andmediumterm.
Photo34:HavingpaidanillegalloggertofellhundredsofcubicmetresofAfricanMahoganyandothertropicalhardwood
onhisdayoff,minerspurchasesawnwoodandcarryitintocamp
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7. MiningexplorationForeverymillion-ouncescaledeposit thatwould interest industrialminers thereare thousandsof
surfacedepositsthatcouldfeedgenerationsofartisanalminers.Artisanalminersgenerallyexplore
atthemarginsofexistingdepositsbymakingtestexcavationsandpanningsmallsamplestocheck
forvisiblegold.Manyjustworkforotherswhohavesomeownershipormanagementofthemines.
Mappingouttherealsocialstructuresandorganizationalarrangement isbeyondthescopeofthis
environmentalassessment,but isan important topic thatneeds tobestudied,especiallyas ithas
importantimplicationsontheadoptionofimprovedenvironmentalpracticesbyminers.
Minerswill expand favourable excavations into amine and continue as long as they canmeet or
exceed theirdailyneeds. Theydo thiseitherbyopeningupmore surfacedeposits laterally,orby
chasingdepositsdeeperintothegroundbydiggingtunnels.Theirapproachshouldbeexpandedto
includeexploration,mineclosure,healthandsafety,andmineplanning.Tunnelsarecreatedwithout
a thought to ventilation, stabilization, or the location and extent of other tunnels. This leads to
collapsesoftunnelsthatundermineeachother,inadditiontonaturalones.Speleologicalsurveysof
tunnelsareneededfortrackingandavoidanceofman-madecave-ins.
Photo35:Openingnewgroundforexploitation.Technicalguidanceisneededtohelpminerslocategolddepositsandplan
extractionaccordingly
Minersalreadyhave limitedsystemstoorganize forwardthinkingworkthatdoesnot immediately
produce gold. For example, a large number of workers in Butuzi were observed excavating
overburden in search of new gold ore at the margins of existing workings. Furthermore, in
Kafiawemamanyminerswereworkingtoopennewexcavationsandbuttressdeeperpartsoftheir
mine pit. This system for organizing “unproductive” but necessary roles within themining group
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should be studied for possible support of expanded “unproductive” roles such as exploration and
waste management. Not only are these essential roles in a more orderly, formal, and
environmentallyresponsibleminingoperationbuttheycanalsocounterbalancetheunemployment
that can be generated when replacing inefficient methods with best practice mineral processing
methods.
Photo36:SteepslopemininginButuziposesseriousrisksoflandslideswhichcoulddamtheLuzinziRiverbelow
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8. OccupationalsafetyWorkingintheButuziandSomeminesitesisahighriskanddangerousactivity.Thisisduetoboth
the site terrain (steepmountain slopes, inadequately buttressed tunnels, deepopenpits, hazards
fromworkinginareacoveredwithfelledtrees),riskofmercurypoisoning,andtheverylimiteduse
ofpersonalprotectiveequipment(PPE)byminers.
Photos37:Steep-slopeminingisdangerouswork
Somebasicmeasuresandpracticescanbeintroducedtoimproveworkingconditionswhichshould
beaccompaniedwithprovisionofappropriatetrainingandinformation.Thisincludes:
1. Usingwheelbarrowsorhandcartstohaultheorebags.
2. Wearingstronggloves(preferablynon-latex)whenhandlingmercury,particularlyduringtailing
reprocessing and in whole ore amalgamation. Gloves should normally be used during all wet
work.
3. Allmercuryshouldbestored indurablecontainers thatareclearly labelledasmercuryandas
toxic,andcoveredwithalayerofwatertopreventthemercuryfromevaporating.4. Puttingondisposabledustmasksandeyeprotectionwhendrymillingrockore.Notedustmasks
needtoberegularlyreplaced.
5. Safetyhelmetsshouldnormallybewornatalltimeinthesite,particularlyinButuzi.
6. Providesimplefirstaidequipmentattheminesite.
7. Encourageminerstostorecleandrinkingwaterandconstructasanitarypit latrineatthemine
site.
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Photo38:Steep-slopeminingisdangerouswork.Safetyhelmetsanduseofprotectivepersonalequipmentarelacking
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9. Barrierstoformalityandtheartisanalminingpovertytrap
Artisanalminerstendnottoexploreforgolddeposits,butinsteadcongregateinsiteswheregoldis
already being produced. Globally speaking,most known gold deposits are usually orphanedmine
sites, many of which were established in colonial times and are largely exhausted, though the
remnant deposits are still suitable to those seeking a way out of poverty. Some deposits were
singledoutfor internationalminingexplorationprogramswhosedevelopmentdidnotproceedfor
lackofeconomic justificationorsocial license,andthatwerethentakenoverbyminersthatwere
alerted to the site by the presence of these prospectors. Perhaps more commonly, however,
industrialminingprospectorsidentifypotentialmineraltargetsbyseekingoutartisanalminingsites
andusingtheirexcavationsandtunnelstoassesspotentialorebodies.Prospectorsthenproceedto
purchasethemineralrightsfromthegovernmentorthelegaltitleholder,withouttheknowledgeof
artisanalminers operating on site. They then pressure the government to use police andmilitary
forcestoenforcetheirtitlerightsbyremovingthe‘invaders.’
Artisanalminersareoftenseekingentirelydifferentdepositsfromthoseofinteresttolargemining
companies,ordifferentpartsofthesamedeposits.Artisanalminerschaseshalloworeinsparseand
well definedhigh grade veins (in hard rockmining) or strata (in alluvialmining) that require little
investment in excavation and mechanization to operate. Large companies use those deposits to
identify and constrain larger, deeper, lower average grade deposits whose mine life production
would justify massive capital expenditures required to exploit the ore for least cost and highest
returns. Often industrial mines remove the “overburden” (overlying ‘waste’ rock that artisanal
minerswouldexploit) inorder toaccess thedeeper industrial scaledepositwitha largeopenpit.
Theytakeafulllifecycleapproachtominingoperations,inwhichthecostofexploration,excavation,
processing, waste storage andmanagement are compared against the net value of the exported
lifetimeproduction.
Government regulations, particularly mineral title licensing rules, are often structured to favour
largeindustrialminingoperations.Obtainingmineraltitleisoftenthefirstobstacleencounteredby
any artisanalmining project aiming for transparency, formalization, or sustainability, and globally
remains a vexatious and difficult barrier. Governments in Peru, Colombia,Mongolia, Guyana, and
Suriname (among others), as well as in the DRC, are actively wrestling with this challenge with
limitedsuccessduetothemisinformationandcompetingintereststhatattendnationallevelpolicy
changeinitiatives.
In well-functioning property rights regimes, mineral titles expire if the title holder makes no
investment inexplorationor exploitation in the site.Where corruptionand loopholes allow, titles
areoftenrenewedorheldindefinitely,andalloftheknownandmostpromisingmineralconcessions
arealreadyclaimed.Thereforeartisanalminersareoften immediately labelled“illegalminers,”or,
where theirprofitsare funnelled toorganizedcrimeandconflictgroups,“criminalminers.”This is
usuallyagrossoversimplification(artisanalandsmallscaleminersinColombiafundcriminalgroups
involuntarilythroughextortion),buttheperceptiondrivesgovernmentassembliestosetunrealistic
legislative barriers to formalization and development of the artisanal mining sector. As a result,
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
59
minerscannotentertheformaleconomybecausetheycannotobtainlegaltitletothedepositsthey
arealreadyworkingandareunabletonegotiateequitableagreementswithexistingconcessionaires.
Where miners have entered formal contracts with legal concessionaires, their lack of legal
knowledgeorcounselcanproduceabusiveagreementsthatstronglyfavourtheconcessionaireand
establishfeudalarrangementsthatperpetuatedangerous, inefficient,andpollutingpracticeswhile
concentratingexcessivewealthinthehandsofdistanttitleholders.Inthesecases,theyalsotypically
control the mercury supply and therefore may see its reduction as a diminished income.
Furthermore,artisanalminerstypicallylacktheskillsandresourcestoexploreavailableconcessions,
whichareusually so remoteor insecureas tomakeaccessdifficult (and thereforeprovide secure
fundingsourcesforillegalorconflictgroups).
AnartisanalandsmallscalemininglegalloopholeAtransparentgoldsupplyis,bynecessity,alegalone.Legalgoldbydefinitioncomesfromoperators
oflegalconcessions,thereforeformalizationandmineraltitlearethehighestorderpriorityforany
gold transparency program. Congolese provincial governments are currently managing artisanal
mineral titles under a legal loophole: an ingenious reinterpretation of provincial jurisdiction
concerningaggregatemining.
Aggregatesarenon-metallicrockdepositsthatareminedforroadfill,concreteproductionandother
constructionactivities.Thenon-metallicdesignation isusuallyclearlyspecified inaggregatemining
legislations, so the present work-around may not be an intentional regulation. In other ways,
artisanaloperationsarequite similar toaggregatemining,mainly in thesense that theyareoften
mining poorly or un-consolidated materials that are close to the surface with a limited surface
footprint. Therefore aggregate concessions are by definition small, shallow, cheap, and available.
Where they overlap with centrally administered precious metals concessions, there are no real
conflictsofinterestsbecausethelargescaleminersarenotinterestedinthesurfacedepositsother
than as indicators of deeper potential strikes. This differentiation is less clear when considering
alluvialandmediumscaleminingoperators.
Kafiawemaisagoodexamplewhereaggregateconcessionsareusedforsemi-legalpreciousmetals
exploitation.Onememberofthecommunitywasdiggingapitlatrineandfoundagoldbearingvein.
Rather than obtaining a national gold mining concession which would have required travel to
Kinshasawithnocertaintyofbeingable toafford the licensing fee (inpartbecause theminimum
concessionsizemaybeprohibitive,andinpartbecausegoldismorevaluablethanaggregate),the
minersinKafiawemaacquiredanaggregatelicense.Theprojectneedstofurtherinvestigatenational
and provincial mineral concession legislations and para-legal functional agreements under which
minersoperate.
Loopholes that misuse provincial concession rules to circumvent federal ones may be a useful
starting point from which to identify and harmonize the concession rules and establish a clear,
equitable, achievable, and fully legal concession system that is accessible to artisanal miners.
Jurisdictionalconflictcouldberesolvedbydefiningclearrulesforindustrialsectorprospectorsand
developers wishing to operate concessions where small artisanal concessions overlap centrally
administeredconcessions.Oneofthegoalsofartisanalminingdevelopmentorganizationsistofind
a way to establish formal agreements among industrial and artisanal mining groups where their
TechnicalReportforPartnershipAfricaCanada’sJustGoldProject
60
interestsareinpotentialconflict(eventhoughtheyareinterestedindifferentpartsofthedeposit).
Thiskindofharmonizedlegislationcouldbeafirststeptowardthatgoal,thoughitmightalsoreduce
potential international investment because the industrial sector is afraid of the liability issues
concerningpartnershipswiththeinformalsector.Gran-ColombiaGoldinSegovia,Colombia, isone
example of a successful relationship between sectors, and Barrick Gold’s operations in Tanzania
offer a useful case study in the formal sector’s worst scenarios. The latter case is more
representativeofrelationsamongartisanalandindustrialminersglobally.
The insecurity and disorganization of informality preventsminers from investing in exploration or
bestpractices for fearofevictionand seizurebyauthorities. It forcesanopportunistic,migratory,
andmarginal lifestyle onminers and traps them in poverty. This project needs to investigate and
ensurethetruelegalityoftheminingclaimsinwhichtheyareoperating,andusesuccesscasesto
designandpromote the reviewand reformofnationalminingandprovincial regulation so that it
betterandmorerealisticallyservesbothartisanalminersandthestate.
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
61
10.ConclusionsandrecommendationsThis studyshows thatmercurycanbesignificantly reducedandultimatelyeliminatedby replacing
the need for mercury by artisanal miners processing the ore. The strategy should be based on
prioritizing pre-concentration before amalgamation. Efficient pre-concentration incurs gold losses,
soprocessinginallpartsofthechainneedstobeimprovedincludingfrom:explorationandplanning
ofdepositextractionandmineworkings,choiceandpre-processingofore,efficientgrindingforgold
liberation, aswell as concentration andmonitoring of gold in ore andwaste.Overall, higher gold
recovery can be achieved without mercury. Technology transfer and training is an important
pathwaytowardsthatend,assumingnotonlyformalitybutaccesstoinvestmentandservices.
SummaryofrecommendationsIn addressing themultiple environmental challenges at the twoAGM sites, the recommendations
are sequenced by interventions requiring the least investment and training, followed by
progressivelycostlierandmorecomplexchangesthatcanbeaddedwhentheminersarereadyto
take thenext step.Consultationswithminersand local communitieswill need tobeorganized to
obtaintheirviewsandbuy-inontheproposedinterventions.
Mercuryreduction1. Promote use of retorts or fume hoods to recover mercury and reduce exposure and
inhalationoftoxicmercuryvapours.Minersmuststopusingleavesasaretort.
2. Promoteconcentrationanddirectsmeltingasanalternativetowholeoreamalgamation.
3. Improvewater supply andwastemanagement using impermeable reservoirs, refilling old
minepits,andreorganizationofprocessingactivities.Thiswill isolatemercuryreleasesand
reduceinfiltrationofwaterintolandslideinitiationzones.
4. Analyze goldoremineralogy to guide changes inprocessingmethods forbothmilling and
gravityconcentration.
5. Optimize mill feed, speed, duration, and grain size control, also using participatory
controlledtrials(includinginstallationandcomparisonofexistingmillingequipment).
6. Improve existing sluice practices by optimizing flow velocity, feed consistency and
turbulencethroughparticipative,controlledtrialsonsite.
7. Fieldtestdifferentmechanicalconcentrationdevicesonsite,beginningwithshakertables,
spirals,bluebowls,andjigs,usingshorttermtrialsoflabscaleequipment(whichcanalsobe
usedtofurtherupgradeprimaryconcentratestoenabledirectsmelting).
8. Implementbestpracticewetmillingandconcentrationprocesses.Potentialoptionsinclude
usingtheArtisanalGoldCouncilBurkinaFasomicroscaleprocessingplantasamodel9.
9. Usetrenchingandpanning(basic)andpotentiallyalsomoderngeophysicalinstrumentation
(suchaselectromagneticsurveysorother)tostudygoldreservesandplanminingactivities.
9SeeAGCBurkinaFasoUpdatereportandvideofilmEmploiel‘OrArtisanalpourl’AideauDéveloppement.
TechnicalReportforPartnershipAfricaCanada’sJustGoldProject
62
Slopestabilization(Butuzi)1. PlantVetivergrass(Chrysopogonzizanioides)tohelpstabilizethesteepslopesoftheButuzi
minesite.
2. Controldrainagetominimizegroundsaturationanderosion.
3. Buildaconcretelinedcisternandraincollectionsystem.
4. Establishsluicingandamalgamationstationsfarawayfromthedisturbedsitetoreducethe
exposureofminerstoslopefailure.
5. Mapandplantunnellingactivities.
Forestandlandprotection(Some/Kafiawema)1. Systematically reclaimand-backfillmined-outpits.Holescontainingmercurycontaminated
tailings,shouldbecoveredwithonemeterofclayorlaterite,compacted,coveredwithsoil,
andre-vegetated.
2. Restrictwildlifehuntingandtrade.
3. Employ a selective approach to felling trees informed by technical assistance on mining
explorationandplanning.
Occupationalsafety1. Usewheelbarrowsorhandcartstohaultheorebags.
2. Wearstronggloves(preferablynon-latex)whenhandlingmercury,particularlyduringtailing
reprocessingandinwholeoreamalgamation.Glovesshouldnormallybeusedduringallwet
work.
3. Allmercuryshouldbestoredindurablecontainersthatareclearlylabelledasmercuryand
astoxic,andcoveredwithalayerofwatertopreventthemercuryfromevaporating.
4. Usedisposabledustmasksandeyeprotectionwhendrymillingrockore.Notedustmasks
needtoberegularlyreplaced.
5. Safetyhelmetsshouldnormallybewornatalltimeinthesite,particularlyinButuzi.
6. Providesimplefirstaidequipmentattheminesite.
7. Encourageminers to store clean drinkingwater and construct a sanitary pit latrine at the
minesite.
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
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Appendix1:LaboratoryanalysesinterpretationBottlesamplesAllvaluesmeasuredinmg/kg(equivalenttoppm).CanadasoilqualityguidelineHg=6.6mg/kg;InterimfreshwatersedimentqualityguidelineHg=0.17mg/kg
Samplecode
Description Discussionofchemicalanalysis Hg As Pb Au
B1B Riverwestofmarketwheregold
buyersburnamalgam.1-2mwide,
highbanks,resistantoldchannel
basin.Sampleconsistsoffineblack
sandwithmicaflakes.Sample1-10
cmdepthsedimentunderwater.
MugeraRiver.Brownturbid,
surroundedbyagriculturalfields.
Evidenceofmercury
contamination,asexpectedfrom
beingdownstreamofthegold
buyersinthemarketthatburnHg.
Noothermetalsshowelevated
concentrations.
0.03 6 6.5
B2B BLANKsamplebottledatLuzinzi
riversite(b3b)
Thisblankmaterialwassandfrom
aconstructionsiteinBukavu.No
significantmetalconcentrations
present.
0.008
5
1.
8
7.4
B3B LuzinziRivercompositesample,
bimodalimmaturesediment
braidedriverheavilyreworkedby
AGMwithHg.Compositesampleof
quietwatersedimentsupstream
nearfasterflowchannelinslower
channelinthemiddleof
amalgamationarea.Panningis
doneinfasterflownearby,butalso
lotsupstream.
Hglevelsreflectthefactthatthis
entireriverisanartisanalalluvial
mineatthissiteandforseveral
kilometresupstream.Arseniclevels
are100xguidelines.
0.064 71
0
15
B4B LulinjaRivercompositesample
along3mlengthofquietbendin
river;eddybank.Riverisbright
brownturbidfromupstream
mining.Largeblackshalerocks
makesmallrapidsinthefast
flowingrivermiddle.Sedimentis
finesandandmud,brownwith
blackstrata.
LesscontaminatedthanLuzinzi
River,stillevidenceof
amalgamationupstream.
0.034 8.
9
7.5
B5B Heavilyworkedminerbuildriver
braidchannelling,moderatewater
flow,siltybottom.Composite
sample.
LessHgcontaminationthan
expected,andillustrative
differenceinmercury
concentrationascomparedtothe
duplicate.Mercuryvariabilityfar
exceedsthevariabilityinother
elementsbecauseitisdeposited
anddisturbedinpatchy,haphazard
waysbyhumans,whereasthe
othermetalconcentrationsare
0.068 95
0
19
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Samplecode
Description Discussionofchemicalanalysis Hg As Pb Au
morerelatedtobackgroundand
tailingsdischargewhichproduce
moreuniformsignals.
B6B DuplicateofB5B consistentmetalconcentrationsin
bothsamples,Hgvariesmore0.091 86
0
20
B7B Butuziminesiteamalgamation
pond.Muddyyellowwithstanding
water.Severalminers
amalgamatedinthispondatlast
visit2dayspreviously,suggesting
thisisadailyoccurrence.
Ascontaminatedasanamalgam
pondwouldbe.Arsenicis
surprisinglyhigh.
3.6 44
00
61
B8B Backgroundsample.50cmbelow
surface10cmintoscarpface.
Brownmoistsubsoil(Bhorizon)
withsharprocksandsomeroots.
TopofButuziminesite.
Surprisingamountsofmercuryin
theoreitself.Perhapsminershad
beenburningnearby.Thenext
sample,B9B,isabettermercury
backgroundsample.
0.34 19
00
28
B9B GPSmarksmineentrance.Ore
sampletakenintunnel~40mdeep
accordingtominerwhotookthe
sample,butshaftiscircuitous.
Abetterbackgroundsamplefor
mercurybecauseitcamefrom40m
depth.Arseniclevelsareveryhigh.
0.018 35
00
47 <8
B10B Anotheramalgamationpond
sample
TypicallyhighconcentrationsofHg
andAsforamalgamationpondsat
thissite.Interestingvariability
amongtheponds.
0.95 12
00
0
82
B11B Amalgamationpondsample
(compositemixedinthesamplejar
notplasticbag)
Arsenicishighinallpondsbecause
itisconcentratedwiththesulphide
mineralslikepyrite,thenis
discardedwiththeconcentrate
afteramalgamation.
0.74 14
000
28
B12B Luzinziriver5kmnorthand
downstreamofKaziba
Alarminglyhighermercury
concentrationsdownstreamof
mostoftheminingactivity.Isthere
someverynear?Alsointeresting
howtheHgisconsistentwiththe
concentration2kmfurther
downstream.
0.2 43
0
12
B13B Luzinziriver7kmnorthand
downstreamofKaziba
Curiouslyhighmercurycontent 0.26 39
0
14
BConc Concentratesamplefrombanana
barksluice
VeryinterestingthattheHgfrom
thisconcentrate,whichwasnot
exposedtomercury,isstill15x
higherthanthebulkoreinsample
B9B.ItindicatesthatperhapsB8B
reflectspossiblebackground
concentrationsinpartsofthis
depositafterall.
0.27 57
00
110 10-
40
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
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Samplecode
Description Discussionofchemicalanalysis Hg As Pb Au
mleaf Leavesthatwereusedtocapture
mercuryduringamalgamburn
Tensofgramsofleavesas
contaminatedasthisareproduced
anddiscardeddailyateachmine
siteinCongo.
2200
0
M-Ore Quartzoresample Quitelowlevelsofallmetalsother
thangold.Thisgoldvaluematches
thelowestvaluesofthegeological
oresampleanalyzedinCanada.
0.008
2
62 8.1 13
M1B Upstreamofminesite.Clearbrown
quiet2mwidecreekveryslow
almoststill,forestedbanks,muddy.
Handsampledcompositebylocal
personundersupervision,samples
from2mlengthofriver,various
waterdepths,surface1-10cm.
PerhapshighHgindicatesprevious
mininginorupstreamofthissite
hascontaminatedthesediment
already,orthebackgroundlevels
arehigh.Theblanksampleseems
tosuggesthighbackground
regionally.
0.16 3.
1
5.4
M2B Compositesampleincreek
immediatelyupstreamofintakefor
minewatersupply.Teacoloured
waterwithmuddybottom4mwide
withlowtomodestflowandold
forestedbanks.Mbelariver.
PerhapshighHgindicatesprevious
mininginorupstreamofthissite
hascontaminatedthesediment
already,orthebackgroundlevels
arehigh.Theblanksampleseems
tosuggesthighbackground
regionally.
0.11 7.
3
21
M3B Compositesampleattheoutflow
oftheminediversionchannel,4-5
mwide,veryslowflowwithmuddy
bottomandshadingforested
banks.Translucentwithmoderate
turbidity.Sabasabacreek.
Hgis10xthebackgroundand
upstreamvalues1.1 37 12
M4B BlanksampleatsiteM3B,material
wasoriginallyfromasunbaked
termitemound1hourawayfrom
MambasaontheroadfromBunia,
farfrommajorsettlements.
Regionalbackgroundmercury
levelsaremodest0.12 1.
8
6.2
M5B Sluicewasteandamalgamation
pondcompositesample
Hgcontaminationasexpected 6.6 13
0
23
M6B CompositesampleatM5Bsite;5-6
timesreworkedtailings(newHg
addedeachtime)
Asaduplicateoftheprevious
sample,thisagainindicateshow
variablemercuryconcentrationsin
hotspotscanbe;allothermetals
arenearlyidenticalin
concentration.
3.3 11
0
16
M7B Upstreamcompositesample
downstreamofclotheswashing
spot,smallmuddycreek.
Welaterfoundoutthatthiswas
originallywheretheydidtheir
sluicingandamalgamation.
5 13
0
20
TechnicalReportforPartnershipAfricaCanada’sJustGoldProject
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Samplecode
Description Discussionofchemicalanalysis Hg As Pb Au
M8B DuplicateofM7B. Asaduplicateoftheprevious
sample,thisagainindicateshow
variablemercuryconcentrationsin
hotspotscanbe.
0.94 54 7.7
M9B Backgroundsampleofmudfrom
3mdepthinminepitwallin
afternoonshade.Mottledgrey
/brown/redmottledtexturewith
quartzpebblesinit.
LocalbackgroundHgdoesseemto
behigh,consistentwithregional
background.
0.16 31
0
17
M10B Amalgamationpondcomposite
sampleMbembeseminesite.
HighHgconsistentwithlongterm
amalgamationuseinthispond.26 18
0
52
M11B Oldalluvialholesfilledinwithdark
stagnantwater,lookslikemarshes
andlakeswithteacolouredwater.
Compositesampleofrecently
reworkedtailings.
Perfectconditionsformethylation:
contaminatedtailingsinstagnant,
anoxicpondswithhighdissolved
organiccontent.
3.6 10
0
20
M12B "Upstream"intheMbutelecreek.
NB.Thisisallonebigun-reclaimed
alluvialminedisasterthatended
about3yearsagoandispartly
revegetated.Thisspothadatrickle
ofcurrent,clearwaterthatistea
colouredwhendeeper.
Clearlythereisgeneralizedlegacy
Hgcontaminationinthisarea,as
indicatedbythedisturbed
landscape.
0.65 7.
7
5.9
M13B Opensandy/gravellypitcomplexin
whichitwashardtofindfines.
Unreclaimedalluvialdisaster.
Clearlythereisgeneralizedlegacy
Hgcontaminationinthisarea.1.1 17 4.1
M14B Roadcutsample~5cmintocutface
and~1mbelowgroundsurface.
Hardpebblysaprolite,red.
AnotherevenmoreoddHg
enrichmentinthesoil.Local
backgroundisquitehigh.
0.41 4.
1
18
M15B Illegiblesampleinformation.
ProbablyafieldduplicateofM13B
Exactlyequalmercurycontent
comparedwithm13b1.1 48 9.5
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
67
SwabsamplesAllvaluesmeasuredinmicrograms(µg)perwipe.
SampleCode
Description Discussionofchemicalanalysis Hg As Pb
S1B NorthwestcornerofKatudumarket
Kabiza,goldbuyerhut1.5metres
fromburnsite.Swabbedwallunder
roof.
Relativelyhighmercurycontamination,as
expected1.7 0.77 0.54
S2B KatudumarketKabiza,goldbuyer
hut2.4metresfromburnsite.
ModestHgatamodestdistance 0.42 <0.2 13
S3B KatudumarketKabiza,goldbuyer
hut3.7metresfromburnsite.
Lessmercuryfartheraway 0.22 <0.2 3.7
S4B EastendofKatudumarket,FIELD
BLANK
Mercuryfreeblanksuggeststhatcross
contaminationisnotanissue<0.2 <0.2 1.9
S5B EastendofKatudumarketroofpillar
brick
Non-significantresult <0.2 <0.2 1.5
S6B Katudumarket,EastandSouthend Thisvalueishighforbeingontheopposite
sideofthemarket.Possiblythereareother
burnsites?
0.4 <0.2 3.1
S7B KatudumarketEastandNorthend Non-significantresult <0.2 <0.2 <0.2
S8B Katudumarket,middleNorthend
nearrestaurants.
Non-significantresult <0.2 <0.2 <0.2
S9B KatudumarketWestandNorthend
neargoldmarket
Nearertotheburnareatheconcentrations
ofHgrise0.29 <0.2 <0.2
S10B MarketLuakabiri,roofpillarof
market
Non-significantresult <0.2 0.23 0.73
S11B InsideKabizaelementaryschool
classroom,wallnearestmarket
wheregoldbuyerssetup
Non-significantresult <0.2 <0.2 0.9
S12B Duplicateof11 Non-significantresult <0.2 <0.2 3
S13B Wallandtopofroofbeamofschool
classroombesidegoldbuyerhutsin
market.
Non-significantresult <0.2 1.1 0.87
S14B courtyardofgoldbuyerhouse,wall
aboveburnsite
OddnottofindHghere.Perhapsasminers
usuallyburnattheminesiteandthis
person'scharcoalfireisnotanyhotter,it
doesnotemitsignificantamountsofHg?
<0.2 <0.2 0.47
S15B Insidewallofgoldbuyerhouse Non-significantresult <0.2 <0.2 0.45
S16B Insideburnroombehindbuyers
house
Non-significantresult <0.2 <0.2 4.2
S1BUK NeargoldshopchimneyatHotelMt.
Kauzi,Bukavu
Clearlyspongegoldwithresidualmercuryis
foundhere7 2.6 0.4
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SampleCode
Description Discussionofchemicalanalysis Hg As Pb
S2BUK Shadowywallspacebetweengold
shopandhotelnearburnarea.
Hgdecreasesquicklyintheshortdistance
fromthelastsample.1.2 0.29 0.81
M1S Amalgamburnsitewall Definitiveevidenceofhealthhazard.Hgis
relativelylowforbeingimmediatelyabove
theburnsite.
2.1 0.81 <0.2
M2S 5metreswestofM1S,above
amalgamburnareaundertheroof
Hgdecreasesrapidlyasonemovesaway
fromtheburnsite0.52 0.92 <0.2
M3S Swaboftheinsidemercurystorage
roomofPDG'shouse,swabbedroof
beams,undershelves,countertop
andunderside.
Mercurystorageroomiscontaminated 2.9 0.46 0.41
M4S BlanksampleatM3Ssite. Non-significantresult <0.2 <0.2 <0.2
M5S DuplicateofM3S Again,duplicatesshowthatHgvariesmuch
morethanothermetals,butduplicates
generallyagreewithin30%error.
1.9 0.36 0.52
M6S Wallsandroofbeamsabovethe
PDG'sburnsiteatcoveredporchof
hishouse.
ByfarthegreatestHgcontentindustis
abovethecampburnsiteatthePDG's
house.
1200 4.9 0.83
M7S Roofbeamsofkitchenhutwhere
theyburnamalgam
MuchlowerHgthanintheamalgamburn
siteadjacent,consistentwithminershabitof
burningonthefrontporchinsteadofintheir
hut.
69 0.89 0.28
M8S Locationoffirepitwhereamalgam
wasburnedinopenair,thisisdust
sampleof3surroundingtreeswithin
4metresoftheburnsite.
Modestelevatedmercuryindust 3.3 0.34 1.5
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
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Appendix2:LaboratoryanalysesresultsAllsoil,sediment,ore,leavesandwipetestssampleswereanalyzedformercuryandothermetalsbySpiezLaboratoryinSwitzerland.
Thefollowingtableshowssampleswiththemostsignificantamountsofmercury,othermetalsandthegold
ores.
Sample Analysis/Matrix Massfraction Swissthreshold(TVA1)
M6S Mercury/wipetest 1200µg/wipe -
M10B Mercury/sediment 26mg/kg 0.5mg/kg
MLeaf Mercury/leaves 2.2% -
B11B Arsenic/sediment 14000mg/kg 15mg/kg
BConc Copper/concentrate 1100mg/kg 40mg/kg
B9B Gold/ore <8mg/kg -
BConc Gold/concentrate 10–40mg/kg -
M-Ore Gold/quartzore 13mg/kg -
1Swissregulationaboutwastes(TechnischeVerordnungüberAbfälle)
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Laboratoryanalysesresultsforwipetests
UNEPCode
UA-2016-12
Crµg/wipe
Mnµg/wipe
Coµg/wipe
Niµg/wipe
Cuµg/wipe
Znµg/wipe
Asµg/wipe
Cdµg/wipe
Pbµg/wipe
Hgµg/wipe
S1B -15 2.7 18 0.57 1.2 1.7 4.8 0.77 <0.2 0.54 1.7
S2B -16 <0.2 <0.2 <0.2 <0.2 0.25 0.87 <0.2 <0.2 13 0.42
S3B -17 <0.2 1.1 <0.2 <0.2 <0.2 0.24 <0.2 <0.2 3.7 0.22
S4B -18 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 1.9 <0.2
S5B -19 0.8 5.2 <0.2 <0.2 0.22 0.72 <0.2 <0.2 1.5 <0.2
S6B -20 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 3.1 0.4
S7B -21 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2
S8B -22 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2
S9B -23 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 0.29
S10B -24 0.41 9.9 <0.2 <0.2 0.28 1.8 0.23 <0.2 0.73 <0.2
S11B -25 <0.2 4.1 <0.2 <0.2 <0.2 1.2 <0.2 <0.2 0.9 <0.2
S12B -26 0.34 8.5 <0.2 <0.2 0.21 3.1 <0.2 <0.2 3 <0.2
S13B -27 4.3 96 1 2 3 19 1.1 <0.2 0.87 <0.2
S14B -28 <0.2 1.5 <0.2 <0.2 <0.2 88 <0.2 <0.2 0.47 <0.2
S15B -29 <0.2 3.4 0.43 <0.2 <0.2 0.6 <0.2 <0.2 0.45 <0.2
S16B -30 <0.2 4.8 <0.2 <0.2 0.27 510 <0.2 <0.2 4.2 <0.2
S1
BUK
-31 0.88 6.2 <0.2 0.24 0.42 4.7 2.6 <0.2 0.4 7
S2
BUK
-32 2.2 11 0.21 0.42 0.49 1.5 0.29 <0.2 0.81 1.2
M1S -33 <0.2 2.3 <0.2 0.24 <0.2 1.1 0.81 <0.2 <0.2 2.1
M2S -34 <0.2 2.1 <0.2 0.25 0.26 0.41 0.92 <0.2 <0.2 0.52
M3S -35 0.22 1.3 <0.2 0.42 0.5 2 0.46 <0.2 0.41 2.9
M4S -36 <0.2 <0.2 <0.2 <0.2 <0.2 0.55 <0.2 <0.2 <0.2 <0.2
M5S -37 <0.2 0.88 <0.2 0.28 0.22 0.63 0.36 <0.2 0.52 1.9
M6S -38 0.66 6.6 <0.2 0.85 1 2.2 4.9 <0.2 0.83 1200
M7S -39 0.48 28 <0.2 0.68 1.2 4.4 0.89 <0.2 0.28 69
M8S -40 0.22 2.2 <0.2 0.29 0.25 0.9 0.34 <0.2 1.5 3.3
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
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Laboratoryanalysesofmercuryinsoil/sediment/ore/leafsamples:
UNEPCode UA-2016-12 Hgµg/kgdrymatter
B1B -1 30
B2B -2 8.5
B3B -3 64
B4B -4 34
B5B -5 68
B6B -6 91
B7B -7 3600
B8B -8 340
B9B -9 18
B10B -10 950
B11B -11 740
B12B -12 200
B13B -13 260
BConc -14 270
M-Leaf -41 22000000(2.2%)
M-Ore -42 8.2
M1B -43 160
M2B -44 110
M3B -45 1100
M4B -46 120
M5B -47 6600
M6B -48 3300
M7B -49 5000
M8B -50 940
M9B -51 160
M10B -52 26000
M11B -53 3600
M12B -54 650
M13B -55 1100
M15B -56 1100
M14B -57 410
TechnicalReportforPartnershipAfricaCanada’sJustGoldProject
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Laboratoryanalysesofothermetalsinsoil/sediment/oremg/kgdrymatter/l=leached;t=total/*goldonlyinformationalvalues,notaccredited
UNEPCode
UA-2016-12
Cr–lmg/kg
Mn-lmg/kg
Co–lmg/kg
Ni-lmg/kg
Cu–lmg/kg
Zn-lmg/kg
As–lmg/kg
Cd–lmg/kg
Pb–lmg/kg
U–lmg/kg
Au–t*
mg/kg
B1B -1 65 360 14 33 40 84 6 <0.5 6.5 1.2
B2B -2 7.2 54 1.3 4.4 3 18 1.8 <0.5 7.4 3.7
B3B -3 20 250 6.6 12 190 26 710 <0.5 15 6
B4B -4 36 410 7.9 17 22 28 8.9 <0.5 7.5 0.87
B5B -5 20 160 5.7 13 240 16 950 <0.5 19 9.3
B6B -6 19 190 6 13 220 14 860 <0.5 20 9
B7B -7 39 15 1 1.9 500 7.3 4400 <0.5 61 60
B8B -8 69 42 1.1 2.5 170 7.3 1900 <0.5 28 9
B9B -9 25 14 0.71 4.5 710 5.1 3500 <0.5 47 72 <8
B10B -10 58 22 3.2 3.2 920 5.1 12000
<0.5 82 120
B11B -11 47 21 3.2 3.1 770 8.4 14000
<0.5 28 57
B12B -12 23 270 6.7 13 200 77 430 <0.5 12 4.1
B13B -13 30 290 7.9 18 120 41 390 <0.5 14 4.8
BConc
-14 36 40 5.6 11 1100 6.9 5700 <0.5 110 44 Oct-40
M-Ore
-42 12 30 3.5 16 31 12 62 <0.5 8.1 <0.5 13
M1B -43 31 130 8 12 7.4 25 3.1 <0.5 5.4 0.56
M2B -44 100 480 27 37 21 75 7.3 <0.5 21 1.1
M3B -45 24 140 7.6 13 11 25 37 <0.5 12 <0.5
M4B -46 46 400 13 17 16 25 1.8 <0.5 6.2 0.59
EnvironmentalassessmentofmercurypollutionineasternDemocraticRepublicoftheCongo
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UNEPCode
UA-2016-12
Cr–lmg/kg
Mn-lmg/kg
Co–lmg/kg
Ni-lmg/kg
Cu–lmg/kg
Zn-lmg/kg
As–lmg/kg
Cd–lmg/kg
Pb–lmg/kg
U–lmg/kg
Au–t*
mg/kg
M5B -47 33 50 4 22 18 12 130 <0.5 23 <0.5
M6B -48 30 40 3.2 19 15 16 110 <0.5 16 <0.5
M7B -49 19 56 4.6 16 16 15 130 <0.5 20 <0.5
M8B -50 19 120 3.9 5.9 8.5 63 54 <0.5 7.7 <0.5
M9B -51 66 38 4.5 18 42 32 310 <0.5 17 2.3
M10B
-52 20 34 4.1 23 25 19 180 <0.5 52 1
M11B
-53 35 130 4.6 12 14 31 100 <0.5 20 <0.5
M12B
-54 33 280 8.9 11 9.9 25 7.7 <0.5 5.9 <0.5
M13B
-55 30 120 5 8.4 9.7 19 17 <0.5 4.1 <0.5
M15B
-56 15 160 4.8 6.5 57 150 48 <0.5 9.5 <0.5
M14B
-57 21 97 3.1 11 3.4 35 4.1 <0.5 18 6.2
Sinuous patterns from extensive reworking of the Luzinizi riverbed by artisanal miners