jean clement boyeme zogo, university of johannesburg

INTRODUCTION

• Manganore Iron Formation is

slumped into sinkhole structures

of the Campbellrand Subgroup

and occurs exclusively on the

Maremane Dome.

• Maremane Dome is an open

domal structure located between

Postmasburg in the south and

Kathu in the north, in the Northern

Cape Province of South Africa.

• Manganore Iron Formation is

Eroded in the centre of the

Maremane Dome.

IRON ORE BENEFICIATION AFRICA

INTRODUCTION • Manganore Iron Formation hosts bulk of high-

grade deposits of South Africa

• High-grade iron ores are produced at Sishen,

Khumani, Beeshoek and Kolomela (Sishen

South)

• Almost 84% of iron ore produced in South Africa;

• Presence of low grade material 34-36 wt. % Fe

• Hematite and quartz with specific gravity 5.2gcm-3

and 2.7 g.cm-3

• Beeshoek and Khumani mines are operated by

Assmang Ltd;

• 3 types of ore products: Lumpy – Fines – DR

lump;

• Materials containing less than 60 wt. % Fe are

discarded;


STRATIGRAPHY AND OCCURRENCE OF LOW-GRADE IRON ORES

Oxidized and partly ferruginized MIF occurs closely associated with high-grade iron ore; 1. Banded MIF type occurs below high-grade laminated iron ore; 2. Breccia textured type MIF occurs above a chert breccia unit, Wolhaarkop Breccia; Both MIF types has been evaluated from drill cores -(34 -102m thick) and hand samples .


Unconformity

Gamagara Formation

Campbellrand Subgroup

Palin Shale

Dolomite

Wolhaarkop Chert Breccia

BIF Breccia

Iron Ore

Doornfontein Conglomerate

Sishen Shale

Marthaspoort quartzites

Manganore Iron

Formation

BACKGROUND AND MOTIVATIONS: PROJECTS GRIQUALAND WEST BASIN

• Hotazel (This Study)

• Sishen B Grade (Koumba)

• Sep 1B (Koumba)

• Shishen Concentrate (K.)

• Pipeline (Koumba)

• Aquila

• Beeshoek Village

(Assmang)

TRANSVAAL BASIN/ BUSHVELD

• Gulukwane iron project

• Malemane

• Turquoise Moon

• Phoenix (Thabazimbi)

• Zandrivierspoort

SAMPLE COLLECTION • Drilled cores; open pits,

waste damps IRON ORE BENEFICIATION AFRICA

Modified after the Council of Geoscience

PHYSICAL CHARACTERIZATION: Texture & Mineralogy Banded MIF • Randomly alternating chert and hematite bands (<mm to 1cm) • Parallel, wavy, meandering, • Silica bands: chert or red jasper • Iron rich bands: laminated hematite; • Crosscut by fissures and micro-faults • Secondary mineralization • Mineralogy: Hematite/Specularite, Quartz, Apatite,…


Massive Iron Ore

Hematite Lutite Brecia Ore

Hematite Greenalite lutite

Thinly Laminate Ore

Thickly Laminate Ore

BIF/Breccia BIF

BIF Shale

Carbonaceous shale

PHYSICAL CHARACTERIZATION: Texture & Mineralogy


Massive Iron Ore

Hematite Lutite Brecia Ore

Hematite Greenalite lutite

Thinly Laminate Ore

Thickly Laminate Ore

BIF/Breccia BIF

BIF Shale

Carbonaceous shale

Breccia textured MIF • Lies immediately below the banded MIF • Formed in response to the collapse of banded MIF and high-grade

iron ore • Mixture of angular to subrounded fragments of BIF, chert, jasper, old

hematite ore,… • Clasts size: mm to cm • Pore spaces filled by crystalline hematite or specularite - clast or

matrix supported • Mineralogy: Hematite/specularite, Martite, Quartz, minor magnetite

PHYSICAL CHARACTERIZATION: Grain Size Analysis


Sieve Size (µm)

Average Chemical Composi6on of the Breccia-‐textured MIF size frac6ons SiO2 TiO2 Al2O3 Fe2O3 Mn3O4 MgO CaO K2O P2O5 S

(wt. %) (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) (wt. %)

+4000 29.4 0.01 0.24 67.3 0.02 0.10 0.12 0.00 0.10 0.19

-‐4000+2000 27.7 0.03 0.41 67.8 0.02 0.17 0.18 0.04 0.10 0.04

-‐2000+1000 28.2 0.01 0.27 68.7 0.02 0.11 0.13 0.00 0.12 0.11

-‐1000+600 24.9 0.04 0.60 71.6 0.04 0.16 0.17 0.08 0.11 0.01

-‐600+425 21.7 0.05 0.71 76.8 0.07 0.06 0.10 0.10 0.13 0.11

-‐425+212 24.3 0.03 0.68 71.6 0.07 0.15 0.17 0.08 0.13 0.05

-‐212 28.8 0.02 0.35 70.0 0.07 0.01 0.06 0.01 0.13 0.11

Average Chemical Composi6on of the Banded MIF size frac6ons +4000 42.7 0.02 0.29 51.9 0.01 0.12 0.15 0.00 0.11 0.08

-‐4000+2000 41.9 0.01 0.24 54.7 0.01 0.12 0.14 0.00 0.10 0.07

-‐2000+1000 44.2 0.01 0.12 52.5 0.02 0.09 0.10 0.01 0.06 0.05

-‐1000+600 48.5 0.01 0.12 48.1 0.03 0.10 0.11 0.00 0.06 0.11

-‐600+425 47.1 0.02 0.30 49.7 0.05 0.09 0.13 0.01 0.12 0.15

-‐425+212 42.3 0.02 0.43 53.1 0.07 0.18 0.18 0.01 0.11 0.16

-‐212 43.5 0.01 0.23 54.0 0.08 0.24 0.23 0.01 0.05 0.12

• In Breccia MIF: 67.3 to 76.8 wt. % Fe2O3 - (Si : 21.7 – 29.4 wt. %)

• In Banded MIF: 48.1 to 54.7 wt. % Fe2O3 – (Si: 41.9 – 48.5 wt. %)

• Significant iron enrichment up to 76.8 wt.% Fe2O3 in breccia textured

MIF for [-600+425µm]

• Texture important parameter for the liberation of ore mineral

GRAVITY SEPARATION: METHODOLOGY


Gravity Separation: MDS Mintek (mineral density

separator)

• PLC controlled air-pulsed batch jigging

• Separates according to mineral specific gravity

• Cylindrical Chamber: Clamped rings connected to

a water chamber ( Diam.: 385mm; H: 50mm);

• Pulsations: provided by air valves with PLC

controlling the frequency and the upstroke, holding

and release times;

• Input and output pressures: 200kPa/m and 14kPa/

mm;

• Valve Control Pressure: 400kPa/m

• Water flow: 1000l/h

• Residence time: 30 minutes

• Water: first turn to maximum then to low flow

• Sample Collection using a tray

• One layer = ring content

GRAVITY SEPARATION: RESULTS


(1) Breccia Textured MIF Average Layer SG Determina6ons

Layer Dry Mass Mass Cum. Mass M1 M2 M3 M5 Ave. SG Cum. SG SI

No g % % g g g g g.cm-‐3 g.cm-‐3 BoYom 1 4792.2 17.0 17.0 -‐29.8 1.4 2465.2 1902.4 4.63 4.63 0.67

2 4269.7 15.2 32.2 -‐29.0 3.2 2132.0 1608.0 4.33 4.49 0.37 3 4176.2 14.8 47.0 -‐29.6 2.0 2121.0 1583.0 4.18 4.39 0.22 4 3396.4 12.1 59.0 -‐29.8 2.6 1729.0 1268.0 4.03 4.31 0.07 5 3690.2 13.1 72.1 -‐29.4 2.4 1932.0 1406.0 3.90 4.23 0.06 6 3976.2 14.1 86.2 -‐29.2 2.4 2019.0 1438.0 3.67 4.13 0.29 7 2795.6 9.9 96.2 -‐29.4 2.8 1440.4 965.0 3.24 4.01 0.72

Top 8 1079.3 3.8 100.0 -‐29.2 3.0 510.8 308.2 2.98 3.96 0.98 Total 28175.8 100.0 3.96 0.38

(2) Banded MIF Average Layer SG Determina6ons


No g % % g g g g g/cc g/cc BoYom 1 4217.1 18.9 18.9 -‐28.8 3.0 2171.2 1624.4 4.21 4.21 0.72

2 3701.6 16.6 35.6 -‐28.2 4.0 1908.0 1375.8 3.81 4.01 0.31 3 3594.5 16.1 51.7 -‐28.2 3.8 1774.2 1256.0 3.64 3.89 0.15 4 3406.5 15.3 67.0 -‐27.6 4.8 1753.2 1212.4 3.44 3.78 0.05 5 2813.6 12.6 79.7 -‐29.0 2.8 1435.2 959.0 3.22 3.68 0.27 6 2990.7 13.4 93.1 -‐28.8 3.4 1495.2 956.8 2.95 3.55 0.55

Top 7 1537.7 6.9 100.0 -‐28.8 3.6 778.8 477.4 2.88 3.49 0.61 Total 22261.7 100.0 3.49 0.37

M1= Mass of basket in hair; M2= Mass of “water on basket” in air; M3= Sample in air (+ “Water on basket”); M4= Sample in air M3-M2; M5= sample in Water; SG = Specific gravity (= (M4)/[M4-(M5-M1)]

GRAVITY SEPARATION: RESULTS


(1) Breccia Textured MIF Average Layer SG Determina6ons


No g % % g g g g g.cm-‐3 g.cm-‐3 BoYom 1 4792.2 17.0 17.0 -‐29.8 1.4 2465.2 1902.4 4.63 4.63 0.67

2 4269.7 15.2 32.2 -‐29.0 3.2 2132.0 1608.0 4.33 4.49 0.37 3 4176.2 14.8 47.0 -‐29.6 2.0 2121.0 1583.0 4.18 4.39 0.22 4 3396.4 12.1 59.0 -‐29.8 2.6 1729.0 1268.0 4.03 4.31 0.07 5 3690.2 13.1 72.1 -‐29.4 2.4 1932.0 1406.0 3.90 4.23 0.06 6 3976.2 14.1 86.2 -‐29.2 2.4 2019.0 1438.0 3.67 4.13 0.29 7 2795.6 9.9 96.2 -‐29.4 2.8 1440.4 965.0 3.24 4.01 0.72

Top 8 1079.3 3.8 100.0 -‐29.2 3.0 510.8 308.2 2.98 3.96 0.98 Total 28175.8 100.0 3.96 0.38

(2) Banded MIF Average Layer SG Determina6ons


No g % % g g g g g/cc g/cc BoYom 1 4217.1 18.9 18.9 -‐28.8 3.0 2171.2 1624.4 4.21 4.21 0.72

2 3701.6 16.6 35.6 -‐28.2 4.0 1908.0 1375.8 3.81 4.01 0.31 3 3594.5 16.1 51.7 -‐28.2 3.8 1774.2 1256.0 3.64 3.89 0.15 4 3406.5 15.3 67.0 -‐27.6 4.8 1753.2 1212.4 3.44 3.78 0.05 5 2813.6 12.6 79.7 -‐29.0 2.8 1435.2 959.0 3.22 3.68 0.27 6 2990.7 13.4 93.1 -‐28.8 3.4 1495.2 956.8 2.95 3.55 0.55

Top 7 1537.7 6.9 100.0 -‐28.8 3.6 778.8 477.4 2.88 3.49 0.61 Total 22261.7 100.0 3.49 0.37

M1= Mass of basket in hair; M2= Mass of “water on basket” in air; M3= Sample in air (+ “Water on basket”); M4= Sample in air M3-‐M2; M5= sample in Water; SG = Specific gravity (= (M4)/[M4-‐(M5-‐M1)]

CONCLUSION


Chemical and Physical Proper6es • Essen%al from explora%on to metallurgical

processes development stages; • Ore textures: rela%onships between iron-‐bearing

and gangue minerals – predic%on of the communi%on efficiency

• Breccia-‐textured: clast or matrix supported with angular clasts – Easy to liberate;

• Par%cle size analyse: most par%cles were found in -‐4000μm +2000μm;

• 70 wt.% Fe2O3 in <600 μm Breccia textured MIF;

• 54 wt.% Fe2O3 in <425 μm Banded MIF;

• Mineralogy and density of ore and gangues

• Chemical composition: deleterious elements for the smelting characteristics and product quality;

• Magne%c separa%on vs. Froth Flota%on vs. Gravity Separa%on (cheap and environmental friendly);

• Breccia and Banded MIF materials are high Silicon, low P, low Al and low S.

Amenability to Beneficia6on • Equipment requirements: MDS can only

operates par%cles size between 20 to 1mm • Texture of Breccia and Banded MIF: thickness of

individual clasts and bands (iron-‐rich and chert-‐rich) varies from less than a millimetre

• Recovery and Efficiency:

• MDS not suitable for par%cles less than 1 mm;

• Block the filter and impede the pulsing ac%on;

• Ability to process very fine material will Improve significantly the beneficia%on of iron ore by gravity separa%on;

THANK YOU FOR YOUR ATTENTION

IRON ORE BENEFICIATION AFRICA 2014

ACKNOWLEDGEMENTS:

• N.J. BEUKES for the opportunity and for organizing the finances for this project;

• Jens Gutzmer, for the encouragements and the advices;

• Marius Burger and Willem Grobblar (Assmang Ltd, Iron Ore Division)

• Ashma Singh and Sandi Gcangi (Mintek, Mineral Processing Department)

jean clement boyeme zogo, university of johannesburg

Documents

highgrade laminated

old hematite ore

types of ore products

mif types

banded mif type

breccia textured type

ferruginized mif

collapse of banded mif