Rossing - Production Process

8/6/2019 Rossing - Production Process

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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


EXTRACTION

AMMONIA GAS

FILTRATION


DRUMMED

URANIUM OXIDE

TWO - STAGE

SCREENING



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


EXTRACTION

AMMONIA GAS

FILTRATION


DRUMMEDURANIUM OXIDE

TWO - STAGE

SCREENING



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


EXTRACTION

AMMONIA GAS

FILTRATION


DRUMMEDURANIUM OXIDE

TWO - STAGE

SCREENING



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

Rossing - Production Process

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