The Resurrection of Hydrometallurgy’s Own RIP van Winkle ... · Namura Mineral Resources Xemplar...
Transcript of The Resurrection of Hydrometallurgy’s Own RIP van Winkle ... · Namura Mineral Resources Xemplar...
Council for Mineral Technology
The Resurrection of Hydrometallurgy’s Own
RIP van Winkle: UraniumMarthie Kotze
IntroductionØWhy RIP van Winkle??ØTitle character in a story by Washington Irving:v slept for 20 years and didn't recognize the world when he woke
up
v Uranium developments woke up after 25 years: is everything different?
ØRIP currently very topical for uraniumØ In1959 17 plants in RSA; only 1 remainedØRevival in Southern Africav biggest activity in Namibia
Uranium in NamibiaExtract Resources Limited Kalahari Minerals Plc Forsys Metals Corp. Westport Resources Namibia (Pty) Ltd. Dunefield Mining Company Ancash Investments (Pty.) Ltd. Galahad Gold Plc Paladin Resources Ltd Rössing Uranium Ltd Areva (Uramin) Namura Mineral Resources Xemplar Energy Corp. Metals Australia Ltd Bannerman Resources Limited West Australian Metals Ltd Cheetah Minerals Exploration Corporate & Resource Consultants Etruscan Resources Namibia Nam-China Minerals and Development Namibia Mineral Mining Plants & Products Philco Twenty (Pty) Ltd Reptile Investment Four Jaco Floris Smith Nova Energy Ltd. Pitchstone Exploration Ltd. Manica Minerals Ltd., Erongo Energy Ltd Atomredmetzoloto OJSC Reptile Uranium Namibia (Pty) Ltd Mineral Commodities Ltd Africa Uranium Ltd
Indian Ocean
MineralogyØ185 uranium minerals according to US Geological
SurveyØMineralogy can be complexØAssociated metals such as V, Mo, TiØMultitude of processing routesØProcess selection is done carefullyØActive industry from early 1950’sv Learn from lessons in previous cycle and other industries, eg
heap leaching
Uranium in HMDØPast 4 years: major increase in demand for uranium
project work at Mintek due to price hike/demand vLanger Heinrich, Kayelekera, Dominion Reefs, Buffelsfontein, Rand Uranium, Harmony, Valencia, Anglo Gold Ashanti, othersvCarbonate, sulphuric acid leaching: since 1920’svPressure leachingvS/L: flocculants, paste thickening, etcvDirect SX, direct IX, IX + SX (incl. RIP)
ØHMD activities:vResin evaluations, incl. silica issuesvResin durabilityvMetRIX™ demonstrationvHPGR: leaching efficiency?vDiagnostic leachingvBPC stripping: neutralization into column
Leach AspectsØ28% of all production via ISLv Rather hydrometallurgical mining
ØProcess improvements in Leninabad: 2 stage leachv Initial generation of ferrous via acid leach of Fe
vSubsequent aeration and acid leach
ØCarous acid as oxidantvDecrease in acid consumption
ØAcid pugging at Somair and Cominak, NigerØHeap leaching: Trekkopje, SomairØBioleaching: tank and heapØPressure leaching
Pressure LeachingØSince 1950’s
ØRefractory minerals such as brannerite, davidite
ØProduction of acid from associated S-minerals via
flotation
ØIn combination with atmospheric leach
Ø5 alkaline and 5 acid pressure leach plants
globally
ØDominion Reefs in Klerksdorp: 2008
ØKnowledge-base larger
Some Flowsheet OptionsØUranium One, Klerksdorp: CCD èBPC SXèADU
ØEzulwini: CCDèNIMCIXèSXèADU ppt
ØLanger Heinrich: CCD èClarification èFBIXèPpt
ØVaal River South: CCD èNIMCIX èMS SXè ADU
ØTrekkopje: Heap leach è NIMCIXè SDU
ØKayelekera: RIPè direct pptØAngloGold Ashanti: South Uranium upgrade, new
plant at Kopanang: NIMCIX / RIP
Uranium One: BPCs Klerksdorp
AngloGold Ashanti: Vaal River South
RIP: Gold/Uranium RecoveryØ RIP not novel technology:
v Early 1950’s proposed by USA Atomic Energy Commissionv Implemented by Anaconda Co: 3000 t/dv being used in FSU for decades for Au and U3O8v previously applied in some form in USA (baskets)v Relix process: inverted fluidised bed (resin floating at top)
§ demonstrated in pachuca tank, Stilfontein Gold Mine 1970§ West Driefontein: over 2 years§ Small scale demonstration run at NIM§ Mechanically operable, performance poor due to back mixing
Ø Use in Western World limitedØ Some Au RIP plants in Western World:
v but resins different; also operational demands for uranium higherØ Major potential CAPEX and OPEX savings for RIP vs
CCD/filtration, so v large drive to consider RIP especially for low grade ores
Ø Major resin improvements by most large resin manufacturers Ø Kayelekera installing agitated carousel-based RIP, direct ppt
Ø Cost model for MetRIX™: RIP generally more cost effective for uranium recovery from lower grade ores and large throughput
RIP: Opportunities & ConcernsOpportunitiesØ No solid/liquid separationØ No PLS clarification as for fixed bed IX and SXØ Direct precipitation
v Continuous elution: higher grade LSL, purer uranium product v can this consistently provide required product quality??
Major ConcernsØ Silica fouling and impact on OPEX
v Resin lifev Rate of fouling and concomitant regeneration requirementv Effect of silica on resin lifev Management strategy around silica – design to limit uranium
losses to barrenv Optimise resin residence time
Ø Resin durability or potential loss: sensitivity of economics to resin loss
RIP Grade Resins
300 400 500 600 700 800 900 1000 1100 1200
0
20
40
60
80
100
MP1 GT1 MP2 GT2
Cum
ulat
ive,
%
Size, µm
Silica FoulingØ Very little information from literature
Rate of silica foulingØ Silica concentration in PLSØ Temperature of leachØ Leach: pressure vs ambientØ pH or acid content of leachØ Time before PLS is contacted with resin: RIP
probably worseØ Resin residence time in leached pulpØ Silica content on resin
Impact of Silica FoulingØSlows down kinetics of loading
vLower operating capacityvLarger resin flow required to maintain uranium recoveries
ØSlower rate of strippingvLonger residence time in strippingvOften lower stripping efficiencyvLower recoveries in adsorption
ØIncrease in reagent consumption due to larger resin flowratesØCause crud formation in SX (SX on eluate)ØPoorer quality ADU due to silica content
Silica Fouling
1 2 30
4
8
12
16
20
24
SiO
2, %
Cycle of poisoning
MP1; MP2; GT1; GT2
SEM Analysis
0
100
200
300
400
500
600
0 100 200 300 400 500 600 700
0
100
200
300
400
500
600
0 100 200 300 400 500 600 700
Gel type resinSilica content: 0 %
4.47 %; 6 %; 9.1 %
Relative counts
Dis
tanc
e, µ
mMacroporous resin
Silica content: 0 % 6.2 %; 12.3 %; 18 %
Dis
tanc
e, µ
m
SEM+BEI+EDS
Silica Fouling – How?ØSi(OH)4 is neutral specie at pH 2 –v enter resin as non-electrolytev lower degree of crosslinking more favourable
Øquarternary ammonium acts as a precipitant vwhy not throughout resin??
ØHSO42- counter-ion on resin – hydrogen bonding
ØSurface phenomenon – part of solution precipitationv this would indicate that smaller resin with higher surface
area should have higher rate of silica ppt
U3O8 Loading- 24 hrs
0%
10%
20%
30%
40%
50%
60%
0% 5% 10% 15% 20% 25%
SiO2 content
Rela
tive
loss
of U
3O8 m
ax c
apac
ity
MP1 GT1 MP2 GT2
Adsorption: 8 hrs
0%
10%
20%
30%
40%
0% 5% 10% 15% 20% 25% 30%
SiO2 in the resin
Loss
in u
ptak
e af
ter 8
hrs
con
tact
MP GT Linear (MP) Linear (GT)
Sand Attritioning
1 2 3 4 50
5
1 0
1 5
2 0
2 5
3 0
3 5
4 0
4 5
5 0
5 5
1 2 3 4 50
5
1 0
1 5
2 0
2 5
3 0
3 5
4 0
4 5
5 0
5 5
M P 1 n o s i l i c a , c a u s t i c ; n o s i l i c a
6 . 2 % S i O 2 ; 1 2 . 3 % S i O 2 1 8 . 0 % S i O 2 ; L i n e a r f i t t i n g
Cum
ulat
ive lo
ss, %
Cum
ulat
ive lo
ss, %
G T 1 n o s i l i c a , c a u s t i c ; n o s i l i c a
4 . 5 % S i O 2 ; 6 . 0 % S i O 2 9 . 1 % S i O 2 ; L i n e a r f i t t i n g
C y c l e s
MetRIX™ Demonstration plant
ConclusionsØWhat did RIP find?ØVery different world, eg communication, etc.ØVery little ‘novel’ in uranium hydrometvBPCs for direct SX, even lower gradevHeap leaching, incl. biovOthers eg. radiometric sortingvFlotation for S-minerals and/or uraniumvS/L separation: PBCs, paste and high rate thickeners,etc
In HMDØFurther work required to select optimum resin typevWhat is optimum SiO2 content on resin: durability, reagent consumption, residence time ?
ØSilica management – solution and resinØFurther durability work in MetRIX™ demonstration plant –to be published in JulyØDirect precipitation from RIP eluate – main drivers:vCAPEX and OPEX for SX circuit (fire issues)vLower acid concentration required to minimise neutralisation costsvPurity??
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