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Uranium Oxide Production at
Rssing UraniumA process overview
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Summary of the Rssing Process
Single product - U3O
8
Low grade deposit - 0.340kg/t U3O
8
Conventional shovel truck open pit.
Sulphuric acid leach process
Product is sold forward on long termcontracts
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Key Metallurgical Parameters
U3O
8grade
Acid consumption rate (Calc Index)
Settling characteristics
Geological make-up (Ore Type)
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Hauling
Haulpak 730E Truck Capacity = 180 tonnes
Employ Trolley Assist
1200 - 1400 volts DC 4 km of trolley line
Save N$ 0.35/tonne
Fuel Consumption365 l/hr -> 20 l/hr
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Processing Plant
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QUARTERNARY
CRUSHERS
RUN OF MINE ORE
PRIMARY CRUSHER S
SECONDARY CRUSHERS
TERTIARY CRUSHERS
RODMILLS
ACID +
Conarc Dust
FERRIC
REACTORS
LEACH
TANKS
CYCLONES
THICKENERS
ROTOSCOOPS
ACID
OXIDANTS
COMBINED TAILINGS
TO DAM BARREN SOLUTION
PREGNANT SOLUTION
BARREN SOLUTION
AMMONIUM HYDROXIDESOLVENT
EXTRACTION
AMMONIA GAS
FILTRATION
PRECIPITATIONCALCINING
DRUMMED
URANIUM OXIDE
TWO - STAGE
SCREENING
FINE CRUSHINGLEACHING
TAILINGSSANDS/SLIMES
SEPARATION
RECOVERY
Reduction
Extraction
Recovery
QUARTERNARY
CRUSHERS
RUN OF MINE ORE
PRIMARY CRUSHER S
SECONDARY CRUSHERS
TERTIARY CRUSHERS
RODMILLS
ACID +
Conarc Dust
FERRIC
REACTORS
LEACH
TANKS
CYCLONES
THICKENERS
ROTOSCOOPS
ACID
OXIDANTS
COMBINED TAILINGS
TO DAM BARREN SOLUTION
PREGNANT SOLUTION
BARREN SOLUTION
AMMONIUM HYDROXIDESOLVENT
EXTRACTION
AMMONIA GAS
FILTRATION
PRECIPITATIONCALCINING
DRUMMED
URANIUM OXIDE
TWO - STAGE
SCREENING
FINE CRUSHINGLEACHING
TAILINGSSANDS/SLIMES
SEPARATION
RECOVERY
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Primary Crushers
Operating Parameters:
Two Primary Crushers fed withrun off mine material toproduce product size of less
than 155mm Crushing Rate 2500-2600tph
Crusher make is the OsbornGyratory (54/74)
Crusher product is fed onto aCoarse Ore stock pile withcapacity of 250 000 tonnes
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Pre-Screening Plant
Removes the already fine material that is
less than 15 mm
Removes approximately 30% of materialto Fine Ore Stockpile
Consists out of 1 set of scalping grizzly
screens and 1 set of banana screens. Commissioned - 1999
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Fine Crushing Plant
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Fine Crushing Plant
Plant capacity of 2300 tph
Closed circuit plant
Two secondary crushers
Four tertiary screens
Four tertiary crushers
Six quaternary screens
Two quaternary crushers
Product size = -17 mm
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Rodmills
Four rod-mills in parallel Feed rate = 560 tph / mill
Open circuit grinding
Wet grinding (using
recycled solution)
Product size 30% +850
microns/20 mesh
Product size D80 is 1.1mm
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Leach Process
Sulphuric acid leaching 2 Modules
Six leach tanks per module
Tank capacity 1 Small mixing tank = 290 m3
5 Large tanks = 1450 m3
Retention time 8 - 9 hours
Leach temperature 35 C
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Mineral Composition Leach Feed
Uranium bearing minerals:uranium at Rssing occurs in the form of
uraninite, uranophane and betafite and is
found in alaskite Gangue minerals:
calcite (marble) makes up a very small
proportion of the ore and is the majorconsumer of acid in Rssing ore
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Factors That Influence the Rate of
Dissolving Uranium From Rssing Ore
Controllable leach parameters.
1. Grind (30% +20Mesh).
2. Reagent Concentrations
- Acid & Oxidants
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Washing Circuit
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Washing Circuit
Solid liquid separation processCyclones
Roto-scoops
ThickenersProduct solution contains uranium ina sulphate form (Uranyl Sulphate)
Concentration of pregnant solution is0.180 g/l (uranium)
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Continuous Ion Exchange
Concentration stageAdsorption process (contacting vessels)
Ionic resin beads
Elution process (eluting columns)
Acidic solution (10% acid)
Concentrated Eluate is Uranyl sulphate
Product solution 4 - 5 g/l (uranium)
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Solvent Extraction
Concentration and Purification stage Mixer settler units
Liquid-liquid ion exchange process
Organic tertiary amine is used as Extractant
Ammonium sulphate is used as stripping
medium
Product solution is uranyl sulphate
Concentration of uranium in product:13-15 g/l
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Final Product Recovery
Optimum precipitation takes place at pH 7.3
Ammonia is used to raise pH
Ammonium di-uranate is precipitated
De-watering process thickener drum filters
Roasting process at 830CProduct quality is more than 98% U3O8
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QUARTERNARY
CRUSHERS
RUN OF MINE ORE
PRIMARY CRUSHER S
SECONDARY CRUSHERS
TERTIARY CRUSHERS
RODMILLS
ACID +
Conarc Dust
FERRIC
REACTORS
LEACH
TANKS
CYCLONESTHICKENERS
ROTOSCOOPS
ACID
OXIDANTS
COMBINED TAILINGS
TO DAM
BARREN SOLUTION
PREGNANT SOLUTION
BARREN SOLUTION
AMMONIUM HYDROXIDESOLVENT
EXTRACTION
AMMONIA GAS
FILTRATION
PRECIPITATIONCALCINING
DRUMMEDURANIUM OXIDE
TWO - STAGE
SCREENING
FINE CRUSHINGLEACHING
TAILINGSSANDS/SLIMES
SEPARATION
RECOVERY
Reduction
Extraction
Recovery
QUARTERNARY
CRUSHERS
RUN OF MINE ORE
PRIMARY CRUSHER S
SECONDARY CRUSHERS
TERTIARY CRUSHERS
RODMILLS
ACID +
Conarc Dust
FERRIC
REACTORS
LEACH
TANKS
CYCLONESTHICKENERS
ROTOSCOOPS
ACID
OXIDANTS
COMBINED TAILINGS
TO DAM
BARREN SOLUTION
PREGNANT SOLUTION
BARREN SOLUTION
AMMONIUM HYDROXIDESOLVENT
EXTRACTION
AMMONIA GAS
FILTRATION
PRECIPITATIONCALCINING
DRUMMEDURANIUM OXIDE
TWO - STAGE
SCREENING
FINE CRUSHINGLEACHING
TAILINGSSANDS/SLIMES
SEPARATION
RECOVERY
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Questions ?
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Roto-scoopsOVERFLOW TO
THICKENER CIRCUIT
LEACH PLANT DISCHARGE
CYCLONE
UNDERFLOW TO
1ST STAGE ROTOSCOOP SANDS TO 2ND
STAGE ROTOSCOOP
BARREN SOLUTIONFROM CIX
2ND STAGE OVERFLOW =
WASH SOLUTION TO 1ST
STAGE ROTOSCOOP
WASHED SANDS TO TAILINGSFIRST STAGE OVERFLOW
RETURNS TO JOIN LEACH
DISCHARGE AND CYCLONE
FEED
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ThickenersPATH OF SLIMES THROUGH THE THICKENERS
CYCLONE OVERFLOW
FROM ROTOSCOOP
SECTION
WASHED SLIMES TO TAILINGS
PATH OF SOLUTION THROUGH THE SECTION
BARREN SOLUTION FROM CIX
PREGNANT
SOLUTION
TO CIX
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Continuous Ion Exchange
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Solvent Exchange
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Final
Product
Recovery
OK LIQUOR
FROM SX
NH3 GAS
PRECIPITATION
YELLOW CAKE THICKENER
AMMONIUM
SULPHATETO SX PLANT
WATER WATER
STORAGE STORAGEFIRST STAGE
FILTER, WASH
AND REPULP
SECOND STAGE
FILTER, WASH
AND REPULP
6 HEARTH
CALCININGFURNACE
THICKENER UNDERFLOW SG 1.3 - 1.5
pH 7.2-7.3
HAMMER MILL
DRUMMED
URANIUMCALCINED
PRODUCT