David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel

David G Dixon, UBC Hydrometallurgy GALVANOXTM  A Novel

David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates GALVANOXTM A Novel Process for the Treatment of Copper Concentrates David G. Dixon UBC Hydrometallurgy David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates PRESENTATION OUTLINE GALVANOX HISTORY GALVANOX FEATURES GALVANOX CHEMISTRY BATCH LEACHING RESULTS PILOT LEACHING RESULTS PROCESS FLOWSHEET OPTIONS PROCESS COMPARISONS COMMERCIAL EVALUATION CONCLUSIONS David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates

GALVANOX HISTORY UBC researchers Dave Dixon and Alain Tshilombo developed a novel process for galvanically-assisted atmospheric leaching of primary copper concentrates in early 2004. A preliminary patent application was filed in June 2004. Several patent applications were filed in 2005 (US, Chile, Peru, Laos), and successful PCT examination in September 2006 spawned many other national phase applications. UBC entered into an exclusive marketing agreement with Bateman Engineering in October 2006, and is working closely with Bateman to identify potential applications of the process. Batch testing programs on many candidate concentrates have been initiated or completed, continuous leaching was piloted in May, and three detailed feasibility studies are currently underway, with integrated pilot campaigns planned to begin in November. David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates GALVANOX FEATURES Atmospheric Leach (~80C) No microbes Pure sulphate medium (no chloride) Conventional materials of construction

No fine grinding Generates elemental sulfur (> 95%), low oxygen demand No surfactants Selective for chalcopyrite over pyrite (can cost-effectively treat low grade concentrates down to 9% copper or less) Complete copper recovery, typically in less than 12 hours, and sometimes in as little as 4 hours Fully compatible with conventional SX-EW David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates GALVANOX CHEMISTRY GALVANOX takes advantage of the galvanic effect between chalcopyrite and pyrite. Chalcopyrite is a semiconductor, and therefore corrodes electrochemically in oxidizing solutions. In ferric sulphate media, the overall leaching reaction is as follows: CuFeS2 + 2 Fe2(SO4)3 CuSO4 + 5 FeSO4 + 2 S0 This reaction may be represented as a combination of anodic and cathodic half-cell reactions: Anodic:

CuFeS2 Cu2+ + Fe2+ + 2 S0 + 4 e Cathodic: 4 Fe3+ + 4 e 4 Fe2+ David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates UNASSISTED CHALCOPYRITE LEACHING So Cu2+ 4 Fe3+ 4 e- Fe2+ 4 Fe2+ CuFeS2 Anodic Site Cathodic Site

David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates UNASSISTED CHALCOPYRITE LEACHING David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates GALVANOX CHEMISTRY Typically, chalcopyrite surfaces are passivated (i.e., they become resistant to electrochemical breakdown) in ferric sulfate solutions at even modest solution potential levels. It is widely held that this results from the formation of some sort of passivating film on the mineral surface that most likely consists of an altered, partially Fe-depleted sulfide layer. Because of this, most investigators have assumed that it is the anodic half-cell reaction that limits the overall rate of leaching. However, we discovered that it is primarily the cathodic half-cell reaction (i.e., ferric reduction) that is slow on the passivated chalcopyrite surface. David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates

GALVANOX CHEMISTRY The presence of pyrite facilitates chalcopyrite leaching by providing an alternative surface for ferric reduction This essentially eliminates cathodic passivation of chalcopyrite in ferric sulfate solutions. Also, by ensuring rapid chalcopyrite oxidation, the solution potential is easily maintained at levels low enough to prevent anodic passivation of the chalcopyrite This also prevents anodic breakdown of the pyrite, which remains more or less completely inert. David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates GALVANICALLY-ASSISTED CHALCOPYRITE LEACHING Py Cu2+ 4 Fe3+ Cp 4 e- 4 e-

4 Fe2+ Fe2+ So Anodic Site Py Cathodic Site David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates GALVANICALLY-ASSISTED CHALCOPYRITE LEACHING Partially leached particle Completely leached particles David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates GALVANOX CHEMISTRY

The ferric required for GALVANOX leaching is regenerated in situ with oxygen gas Ferric leaching of chalcopyrite: CuFeS2 + 2 Fe2(SO4)3 CuSO4 + 5 FeSO4 + 2 S0 Oxidation of ferrous with dissolved oxygen gas: 4 FeSO4 + O2 + 2 H2SO4 2 Fe2(SO4)3 + 2 H2O Overall leaching reaction: CuFeS2 + O2 + 2 H2SO4 CuSO4 + FeSO4 + 2 S0 + 2 H2O David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates GALVANOX CHEMISTRY GALVANOX leaching is followed by conventional solvent extraction and electrowinning to recover LME Grade A pure copper cathodes Copper electrowinning: CuSO4 + H2O Cu0 + O2 + H2SO4 David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates GALVANOX CHEMISTRY Iron is rejected from the Galvanox circuit by oxyhydrolysis in an autoclave at ~220C to make hematite, which is easy to filter and perfectly suitable for disposal

Iron oxyhydrolysis: 4 FeSO4 + O2 + 4 H2O 2 Fe2O3 (s) + 4 H2SO4 This autoclave also treats a portion of the concentrate feed, in order to generate the heat required for the atmospheric leach circuit, and also to generate extra acid as required for secondary sulfides or acidconsuming gangue minerals in the concentrate David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates GALVANOX CHEMISTRY In summary, the overall GALVANOX process chemistry is as follows: Galvanically-assisted atmospheric leaching of chalcopyrite: CuFeS2 + O2 + 2 H2SO4 CuSO4 + FeSO4 + 2 S0 + 2 H2O Iron oxyhydrolysis: FeSO4 + O2 + H2O Fe2O3 (s) + H2SO4 Copper electrowinning: CuSO4 + H2O Cu0 + O2 + H2SO4 Overall process chemistry: CuFeS2 + 5/4 O2 Cu0 + 2 S0 + O2 + Fe2O3 (s) David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates BATCH TESTING APPARATUS

Six 3-L jacketed reactors Water baths for temperature control Digital oxygen mass flow meters for potential control Automated data acquisition for potential, pH and temperature David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates CHALCOPYRITE CONCENTRATE 35% Cu Effect of pyrite addition (50 g con, 65 g acid, 470 mV, 80C) 100% 90% 80% Cu Recovery 70% 60% 50% 40% 30%

Py = 150 g (K5) Py = 100 g (K9) Py = 50 g (K6) Py = 25 g (K10) Py = 0 g (K1) 20% 10% 0% 0 4 8 12 Time (h) 16 20 24

David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates CHALCOPYRITE CONCENTRATE 35% Cu Effect of sulfuric acid addition (50 g con, 100 g Py, 470 mV, 80C) 100% 90% 80% Cu Recovery 70% 60% 50% 40% 30% Ac = 90 g (1.80 kg/kg) (K16) Ac = 80 g (1.60 kg/kg) (K14) Ac = 68 g (1.36 kg/kg) (K9) Ac = 55 g (1.10 kg/kg) (K13) Ac = 45 g (0.90 kg/kg) (K15) 20%

10% 0% 0 4 8 12 Time (h) 16 20 24 David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates CHALCOPYRITE CONCENTRATE 35% Cu Effect of solution potential (50 g con, 100 g Py, 90 g acid, 80C) 100% 90%

80% Cu Recovery 70% 60% 50% 40% 30% E = 485 mV (K20) E = 470 mV (K16) E = 455 mV (K19) E = 440 mV (K18) E = 425 mV (K17) 20% 10% 0% 0 4 8 12

Time (h) 16 20 24 David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates CHALCOPYRITE CONCENTRATE 35% Cu Effect of solution potential (50 g con, 100 g Py, 90 g acid, 80C) 500 Solution Potential (mV vs Ag/AgCl) 490 480 470 460 450 440 430

420 410 400 0 4 8 12 Time (h) 16 20 24 David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates CHALCOPYRITE CONCENTRATE 35% Cu Effect of temperature (50 g con, 100 g Py, 90 g acid, 470 mV) 100%

90% 80% Cu Recovery 70% 60% 50% 40% 30% 20% T = 80C (K16) T = 70C (K22) T = 60C (K21) 10% 0% 0 4 8 12

Time (h) 16 20 24 David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates CHALCOPYRITE CONCENTRATE 35% Cu Effect of pyrite recycle (50 g con, 100 g Py, 90 g acid, 470 mV, 80C) 100% 90% 80% Cu Recovery 70% 60% 50% 40% 30% Baseline (K16)

Alt. Baseline (K25A) + K25A Continued (K25B) + K5 Residue + 7.5 g Cu (K24) + K8 Residue (K23) 20% 10% 0% 0 4 8 12 Time (h) 16 20 24 David G Dixon, UBC Hydrometallurgy

GALVANOXTM A Novel Process for Copper Concentrates CHALCOPYRITE CONCENTRATE 35% Cu At constant solution potential, pH is an indicator of reaction progress 1.4 100% 90% 1.3 80% 1.2 60% 1.1 pH Cu Recovery 70% 50% 1

40% 30% 0.9 20% Alt. Baseline (K25A) 10% + K25A Continued (K25B) 0.8 + K5 Residue + 7.5 g Cu (K24) 0.7 0% 0 4 8

Time (h) 12 0 4 8 Time (h) 12 David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates CHALCOPYRITE CONC 2 23.6% Cu Effect of pyrite addition (30 g con, 120 g Py, 30 g acid, 480 mV, 80C) 100% 90% 80% Cu Recovery

70% 60% 50% 40% 30% 20% Galvanox Leaching 10% No Pyrite 0% 0 4 8 12 Time (h) 16

20 24 David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates CHALCOPYRITE CONC 3 24.1% Cu Effect of pyrite addition (10 g con, 40 g Py, 15 g acid, 470 mV, 80C) 100% 90% 80% Cu Recovery 70% 60% 50% 40% 30% 20% Galvanox Leaching 10%

No Pyrite 0% 0 4 8 12 Time (h) 16 20 24 David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates CHALCOPYRITE CONC 4 20.1% Cu Effect of pyrite addition (57 g con, 112 g Py, 60 g acid, 450 mV, 80C)

100% 90% 80% Cu Recovery 70% 60% 50% 40% 30% 20% Galvanox Leaching 10% No Pyrite 0% 0 4 8

12 Time (h) 16 20 24 David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates CHALCOPYRITE BULK CONC 10.2% Cu 150 g bulk con @ ~1.21 Py/Cp ratio, 75 g acid, 440 mV, 80C) 100% 90% 80% Cu Recovery 70% 60% 50% 40%

30% 20% 10% 0% 0 4 8 12 Time (h) 16 20 24 David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates BULK CONC RESIDUE 22.8 g/t Au 77 g Galvanox residue @ 0.5 g/L NaCN, pH 11, room temp

6 100% 90% 5 80% NaCN consumption (kg/t) Au extraction 70% 60% 50% 40% 30% 20% 4 3 2

1 10% 0 0% 0 12 24 Time (h) 36 48 0 12 24 Time (h) 36

48 David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates SUMMARY OF LEACH RESULTS GALVANOX is robust (insensitive to the source of chalcopyrite) Process optimization is straightforward: Pyrite-to-chalcopyrite ratio (2:1 to 4:1 typically optimal) Acid concentration (stoichiometric + modest excess) Solution potential (> 440 mV) Temperature (> 70C) Recycled pyrite is equally as effective as fresh pyrite Under the correct process conditions, GALVANOX leaching is very rapid (limited by the rate of gas-liquid mixing) High Au extractions from GALVANOX residues are feasible, with relatively modest cyanide consumption levels David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates FIRST GALVANOX COPPER (99.85% Cu directly from PLS at 50 g/L Fe!)

David G Dixon, UBC Hydrometallurgy GALVANOXTM A Novel Process for Copper Concentrates QUESTIONS ? For more information, please visit: www.GALVANOX.com

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