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					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 (~80°C)
 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                                     4 Fe3+
                          Cp
 Cu2+

                         4 e-
                                          4 e-
                                                           4 Fe2+
Fe2+
                          So         Py            Cathodic Site
     Anodic 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 + ½ 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 ~220°C 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 acid-
  consuming 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 + ¼ O2 + H2O → ½ Fe2O3 (s) + H2SO4
  Copper electrowinning:
                CuSO4 + H2O → Cu0 + ½ O2 ↑ + H2SO4
  Overall process chemistry:
        CuFeS2 + 5/4 O2 → Cu0 + 2 S0 + ½ O2 ↑ + ½ 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, 80°C)

                  100%

                  90%

                  80%

                  70%
    Cu Recovery




                  60%

                  50%

                  40%

                  30%
                                                         Py = 150 g (K5)
                  20%                                    Py = 100 g (K9)
                                                         Py = 50 g (K6)
                  10%                                    Py = 25 g (K10)
                                                         Py = 0 g (K1)
                   0%
                         0   4   8    12        16      20           24
                                     Time (h)
 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, 80°C)

                  100%

                  90%

                  80%

                  70%
    Cu Recovery




                  60%

                  50%

                  40%

                  30%
                                                     Ac = 90 g (1.80 kg/kg) (K16)
                  20%                                Ac = 80 g (1.60 kg/kg) (K14)
                                                     Ac = 68 g (1.36 kg/kg) (K9)
                  10%                                Ac = 55 g (1.10 kg/kg) (K13)
                                                     Ac = 45 g (0.90 kg/kg) (K15)
                   0%
                         0   4   8    12        16             20             24
                                     Time (h)
 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, 80°C)

                  100%

                  90%

                  80%

                  70%
    Cu Recovery




                  60%

                  50%

                  40%

                  30%
                                                        E = 485 mV (K20)
                  20%                                   E = 470 mV (K16)
                                                        E = 455 mV (K19)
                  10%                                   E = 440 mV (K18)
                                                        E = 425 mV (K17)
                   0%
                         0   4   8    12        16      20           24
                                     Time (h)
 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, 80°C)

                                         500

                                         490
    Solution Potential (mV vs Ag/AgCl)




                                         480

                                         470

                                         460

                                         450

                                         440

                                         430

                                         420

                                         410

                                         400
                                               0   4   8    12        16   20   24
                                                           Time (h)
 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%

                  70%
    Cu Recovery




                  60%

                  50%

                  40%

                  30%

                  20%
                                                             T = 80°C (K16)
                  10%                                        T = 70°C (K22)
                                                             T = 60°C (K21)
                   0%
                         0   4   8    12        16      20              24
                                     Time (h)
  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, 80°C)

                   100%

                   90%

                   80%

                   70%
     Cu Recovery




                   60%

                   50%

                   40%

                   30%
                                                  Baseline (K16)
                   20%                            Alt. Baseline (K25A)
                                                  + K25A Continued (K25B)
                   10%                            + K5 Residue + 7.5 g Cu (K24)
                                                  + K8 Residue (K23)
                    0%
                          0   4   8    12        16           20            24
                                      Time (h)
  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

                100%                                                                        1.4

                90%
                                                                                            1.3
                80%

                70%                                                                         1.2
  Cu Recovery




                60%
                                                                                            1.1




                                                                                                  pH
                50%
                                                                                            1
                40%

                30%                                                                         0.9

                20%        Alt. Baseline (K25A)
                                                                                            0.8
                10%        + K25A Continued (K25B)
                           + K5 Residue + 7.5 g Cu (K24)
                 0%                                                                         0.7
                       0        4                 8        12   0   4              8   12
                                    Time (h)                            Time (h)
 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, 80°C)

                  100%

                  90%

                  80%

                  70%
    Cu Recovery




                  60%

                  50%

                  40%

                  30%

                  20%
                                                     Galvanox Leaching
                  10%
                                                     No Pyrite
                   0%
                         0   4   8    12        16       20              24
                                     Time (h)
 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, 80°C)

                  100%

                  90%

                  80%

                  70%
    Cu Recovery




                  60%

                  50%

                  40%

                  30%

                  20%
                                                     Galvanox Leaching
                  10%
                                                     No Pyrite
                   0%
                         0   4   8    12        16        20             24
                                     Time (h)
 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, 80°C)

                  100%

                  90%

                  80%

                  70%
    Cu Recovery




                  60%

                  50%

                  40%

                  30%

                  20%
                                                     Galvanox Leaching
                  10%
                                                     No Pyrite
                   0%
                         0   4   8    12        16        20             24
                                     Time (h)
 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, 80°C)

                  100%

                  90%

                  80%

                  70%
    Cu Recovery




                  60%

                  50%

                  40%

                  30%

                  20%

                  10%

                   0%
                         0   4   8    12        16      20   24
                                     Time (h)
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

                100%                                                           6

                90%
                                                                               5
                80%

                70%




                                                     NaCN consumption (kg/t)
                                                                               4
                60%
Au extraction




                50%                                                            3

                40%
                                                                               2
                30%

                20%
                                                                               1
                10%

                 0%                                                            0
                       0   12    24        36   48                                 0   12    24        36   48
                                Time (h)                                                    Time (h)
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 (> 70°C)
 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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