sustainability important factors –technical –economic –social/political –environmental past...
TRANSCRIPT
Sustainability
• Important Factors– Technical
– Economic
– Social/Political
– Environmental
• Past mining activities focussed on only the first two
• The latter two have now become equally, if not
more important
Sustainability
• A Mine must plan for closure before it starts up
• A mining company must always consider local communities in all parts of the world
• As an industry, we must find ways to enhance our image and to influence government decision-making
• Future methods must reduce the footprint of mining– no more open pits
– waste returned to the mine
– processing at the face
– robotics and remote-mining systems
Sustainability
• The BC Mining Industry must encourage its members to institute vertical integration policies
• We need to invest in much more value-added processing (i.e. smelting and refining in BC)
• Downstream manufacturing industries must be encouraged to develop in BC
• This will provide the necessary systems to begin significant recycling of metals and other materials in the pacific North-West
Sustainability • Social/Political Issues
– Land Use– Government policies– The Influence of Activism– Environmental concerns– Aboriginal peoples and treaties– Need for jobs and a diversified economy
• In BC, the Tatsenshini/Windy Craggy decision has
had important long-term impact on Mining
• Similarly, the Delgamuk decision and Nishka Treaty are important to the future of BC's mining industry
ORE, WASTE and MINERALOGY
• What is an ore?
• What is waste?
• What is the role of mineralogy in MMPE?
• How do these questions change for different commodities?
What is an Ore?
Definition:
An ore is a mass of mineralization within the Earth's surface which can be mined
- at a particular place;
- at a particular time;
- at a profit.
What is Waste?
Definition:
Waste is mineralized rock that is removed from a mine to provide access to an underlying or nearby orebody containing at least one mineral of value.
Types of Waste:
- footwall material ( typically barren material )- hangingwall material ( typically contains sulfides )- gangue material contained within the ore
What is Waste?
Waste rock can become ore at some later point in time.
- metal/commodity prices can change
- other values are discovered within the waste
- new technology is developed
- cost of environmental protection becomes too high
- ore has been exhausted; too costly to close the mine
Mineralogy in MMPE
The types of minerals in the ore have major impact on the operation and control of the processing plant.
- relative abundance of ore minerals- feed grade and concentrate grade
- types of gangue minerals- slime content (clays, etc.)- pH effects (alkali rock)- pyrite and pyrrhotite (iron sulfides)
- association of ore and gangue minerals- liberation characteristics- disseminated vs. massive
Process Mineralogy
- establish regular mineralogical analysis of mill feed and other process streams
- perform a size-by-size analysis of rock and ore mineral contents and associations
- relative abundance- free/locked ratios of grinding circuit
products
- perform metallurgical testwork on ore samples containing different mineralogy
Virtual Atlas of Opaque and Ore Minerals in their Associations <http://www.smenet.org/opaque-ore/>
Process Mineralogy
- establish the metallurgical performance of each process stage for each ore mineral type
- determine in which size ranges, losses are occurring and examine which minerals are responsible for these losses
- establish the influence of impurity minerals on product quality
- use all of the above information to decide on process changes that will improve plant performance with respect to recovery and product quality
Copper Ores
Minerals: Sulfides Oxides chalcopyrite cuprite bornite malachite covellite pseado-malachite
chalcocite azurite cubanite chrysocolla
Gangue Minerals:pyrite arsenopyritequartz feldsparssilicates claysMn-wad calcite
Copper OresOre Types:
Porphyry: igneous rock of large crystal size (phenocrysts) embedded in a ground mass. Typical mineralization is disseminated chalcopyrite with molybdenite.
Massive: pyrite/pyrrhotite host with chalcopyrite, pentlandite, sphalerite, arsenopyrite, galena.
Vein-type: quartz host with veins of chalcopyrite, chalcocite and pyrite
Copper OresProblems:
Liberation:fine grinding may be required.
Recovery: oxide/sufide ratio changes,presence of slime particles,poor recovery of coarse copper minerals.
Product: poor liberation, presence of As, Bi, PbQuality high %H2O, variable Cu grade
Separation: poor distribution of Co, Zn, Pb, etc.
Copper Ores
Anhedral chalcopyrite (yellow, top right) is intergrown with quartz (light grey, right centre). Pounded to euhedral rutile (grey-white, centre left) is disseminated throughout the host rock. The poorly polished dark grey gangue is phyllosilicate. - El Salavdor, Chile
Nickel Ores
Minerals: pentlandite chalcopyrite
Gangue Minerals:pyrrhotitequartz feldsparssilicates claysMn-wad calcite
Nickel OresOre Types:
Massive: pentlandite and chalcopyrite in relatively equal quantities in massive pyrrhotite.
Massive: low copper content in pyrrhotite host.
Massive: presence of clay slimes,chalcopyrite/pentalandite with pyrrhotite
Nickel OresProblems:
Ni-associations: 3 types- as pentlandite- solid-solution in
pyrrhotite- "flame" pentlandite in
pyrrhotite
Liberation: fine grinding may be required for "flame" pentlandite.
Recovery: solid-solution losses.magnetic vs. flotable pyrrhotite
Product: clay contaminationQuality high %H2O, variable Cu/Ni grade
Nickel OresProblems:
Cu-Ni separation: - at milling stage - at the smelting stage - at the matte
separation stage
Synthetic Minerals: heazlewoodite (Ni3S2) chalcocite (Cu2S)Fe-Ni alloy (PMs)
Downstream Processing • Nickel
– Typical Mine/Mill Treatment
Downstream Processing • Nickel
– Matte Separation processing
Nickel Ores
Chalcopyrite, pyrrhotite, pentlandite,
and cubanite - Stillwater, Montana, USA
Notice flame pentlandite in chalcopyrite
Nickel Ores
Pyrrhotite (brown) has pentlandite (light brown, higher
reflectance, centre) exsolution bodies as flames, aligned along (0001). Minor amounts of chalcopyrite (yellow, centre right) are associated with cleavage and fractures within pyrrhotite. Silicates are black.
125µm
Nickel Ore
Rhomb-shaped areas of deeply etched hexagonal pyrrhotite are surrounded by more lightly etched monoclinic pyrrhotite,which is the main phase. Very lightly etched monoclinic pyrrhotite(pale brown, bottom right) has a rim of granular pentlandite(light brown, higher reflectance). Pyrrhotite is intergrown withchalcopyrite (yellow, centre) and encloses magnetite (grey, top left).
Lead/Zinc Ores
Minerals: galena sphalerite
Gangue Minerals:pyrrhotite pyritearsenopyrite talcquartz feldsparssilicates claysMn-wad calcite
Lead/Zinc OresOre Types:
Pb/Zn: galena, sphalerite and pyrite
Cu/Pb: chalcopyrite, galena and pyrite.
Cu/Zn: chalcopyrite, sphalerite and pyrite
Cu/Pb/Zn: chalcopyrite, galena, sphalerite and pyrite
Lead/Zinc OresProblems:
Zn depression: ZnS is readily activated by Cu ions
Cu/Pb separation: essential to avoid Cu smelter penalties
Liberation:difficult to assess without mineralogy
Product: Zn conc > 55-58%ZnQuality Pb conc > 60-65%Pb
Cu conc > 25%Cu
Copper, Lead, Zinc Ores
Euhedral arsenopyrite (white, high reflectance, left) is inter-grown with galena (light blue-white with triangular cleavagepits, centre), chalcopyrite (yellow, centre) and sphalerite (light grey, centre right), with fine chalcopyrite inclusions (top left) or submicroscopicchalcopyrite (grey to brown-grey, centre right). A lath of poorlypolished molybdenite (light grey, centre) is enclosed within chalcopyriteand galena and has partially rimmed arsenopyrite (bottom right). Minor amounts of rutile (light grey) form acicular crystals within the gangue (right centre). Black areas are polishing pits.
Copper, Lead, Zinc Ores
Reniform sphalerite (light grey, centre) is interbanded with galena (white, centre bottom) and chalco-pyrite (yellow) in successive growth rings. Chalcopyrite in thecentre of the right sphalerite has replaced poorly crystalline pyrite (white, top right). Chalcopyrite can be seen to have higher relief than galena (bottom left). The gangue (dark grey) is sulphate. Black areas are polishing pits.
Iron Ores
Minerals: hematite magnetite martite goethite/limonite siderite
Gangue Minerals:quartz feldsparssilicates claysMnO2 calcite
Iron OresOre Types:
high grade hematite: Carajas, Brazil
low grade hematite: Shefferville ores, N. Quebec
hematite/magnetite: Iron Ore Company of Canada, Labrador
hydrated/weathered ores: itabirite and limonitic ores
carbonate ores: Siderite ores (Sault St. Marie)
Iron OresProblems:
magnetite recovery: associations with hematite
gravity separation: fine size liberation
flotation: reverse flotation of gangue
Product: SiO2 content < 2%Quality product size
(lump, sinter feed, pellet feed)magnetite content
Samarco Iron Ore Flowsheet
Samarco Iron Ore Concentrator
Samarco Iron Ore Pipeline
Iron Ore Pellets
Malmberget, Norway
Gold Ores
Minerals: native gold,electrum,telluridesassociated with pyrite and/or other sufides
Waste: quartzpyritearsenopyritefeldsparscalciteother rock-type minerals
Downstream Processing • Gold processing options
Gold Flakes
Gold Panning
Gold Flakes
Grinding and Cyanide LeachingMusslewhite Mine, Ontario
Smelting GoldCampbell Mine, Ontario
Pouring Slag
Musslewhite Mine, Ontario
Pouring Gold Bullion Bars
What its all about!Gold Bullion