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WO2004031453A1 - Extraction electrolytique de metaux - Google Patents

Extraction electrolytique de metaux Download PDF

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Publication number
WO2004031453A1
WO2004031453A1 PCT/ZA2003/000145 ZA0300145W WO2004031453A1 WO 2004031453 A1 WO2004031453 A1 WO 2004031453A1 ZA 0300145 W ZA0300145 W ZA 0300145W WO 2004031453 A1 WO2004031453 A1 WO 2004031453A1
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WO
WIPO (PCT)
Prior art keywords
electrode
cell
solution
collector
metal
Prior art date
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Ceased
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PCT/ZA2003/000145
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English (en)
Inventor
Michael John Sole
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Individual
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Individual
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Publication date
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Priority to AU2003275505A priority Critical patent/AU2003275505A1/en
Publication of WO2004031453A1 publication Critical patent/WO2004031453A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/467—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction
    • C02F1/4676—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction by electroreduction
    • C02F1/4678—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction by electroreduction of metals
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B11/00—Obtaining noble metals
    • C22B11/04—Obtaining noble metals by wet processes
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B11/00—Obtaining noble metals
    • C22B11/04—Obtaining noble metals by wet processes
    • C22B11/042—Recovery of noble metals from waste materials
    • C22B11/046—Recovery of noble metals from waste materials from manufactured products, e.g. from printed circuit boards, from photographic films, paper or baths
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
    • C25C1/20—Electrolytic production, recovery or refining of metals by electrolysis of solutions of noble metals
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/46104—Devices therefor; Their operating or servicing
    • C02F1/46109—Electrodes
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/46104—Devices therefor; Their operating or servicing
    • C02F1/46109—Electrodes
    • C02F2001/46133—Electrodes characterised by the material
    • C02F2001/46138—Electrodes comprising a substrate and a coating
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/46104—Devices therefor; Their operating or servicing
    • C02F1/46109—Electrodes
    • C02F2001/46152—Electrodes characterised by the shape or form
    • C02F2001/46157—Perforated or foraminous electrodes
    • C02F2001/46161—Porous electrodes
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/20—Heavy metals or heavy metal compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2201/00—Apparatus for treatment of water, waste water or sewage
    • C02F2201/46—Apparatus for electrochemical processes
    • C02F2201/461—Electrolysis apparatus
    • C02F2201/46105—Details relating to the electrolytic devices
    • C02F2201/4616—Power supply
    • C02F2201/4617—DC only
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2201/00—Apparatus for treatment of water, waste water or sewage
    • C02F2201/46—Apparatus for electrochemical processes
    • C02F2201/461—Electrolysis apparatus
    • C02F2201/46105—Details relating to the electrolytic devices
    • C02F2201/4616—Power supply
    • C02F2201/46175—Electrical pulses
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • This invention relates to the winning of metals.
  • This solution is passed through columns containing activated carbon which preferentially adsorbs the gold. After loading is complete the columns are eluted with a hot caustic solution to yield a gold eluate solution containing typically 650 ppm gold. The carbon is heated to regenerate it from time to time. The eluate then passes through electro winning cells where the gold is electro deposited on to cathodes of knitted stainless steel wool. The loaded cathodes are removed periodically and manually washed using high pressure water jets to dislodge a gold sludge. This is filtered, after which the filter cake is smelted and cast into impure gold bars. These bars are sent to a refinery, which is generally at a remote location, for further purification.
  • an electro winning cell comprising a housing; a first electrode within the housing; second electrode means within the housing and including collector electrode means electrical connections to the electrodes and switching means for connection to the positive and negative terminals of a power source, the switching means being arranged so that in use the first electrode may be connected selectively to the negative and positive terminals and that the second electrode means will be connected to the other of such terminals.
  • the switching means being arranged so that in use the first electrode may be connected selectively to the negative and positive terminals and that the second electrode means will be connected to the other of such terminals.
  • the first electrode acts as a cathode
  • the second electrode switching means acts as an anode.
  • the second electrode means comprises a second electrode and the collector electrode means, and the switch means is arranged so that (a) when the first electrode is connected to act as a cathode, the second electrode is connected to act as an anode and the collector electrode means are isolated and (b) when the first electrode is connected to act as an anode, the second electrode is isolated and the collector electrode means acts as a cathode.
  • the second electrode means may comprise a single electrode which acts as the collector electrode when cathodic.
  • the first electrode means is preferably a high surface area member. It preferably comprises a first electrically conductive member and a second member which has a high surface area material which latter is often does not have good electrically conductive characteristics.
  • the first member is preferably a mesh or expanded metal and is herein referred to as a "meshed member” .
  • the second member is hereinafter referred to as a pored member.
  • the first member is preferably in close electrical and physical relationship with the second, pored, member.
  • the cell is used in combination with a source of electric current.
  • a method of electrowinning metal comprising passing a solution loaded with metal into a cell in the combination as set out above; connecting the first electrode to the negative terminal of the source of electrical power so that it acts as a cathode, connecting the electrode means to the positive terminal of the source of electrical power so that it acts as an anode treating the solution to load the first electrode with metal and thereafter connecting the first electrode to the positive terminal of the electric power source and the electrode means to the negative terminal so that the metal loaded on to the first electrode is transferred to the collector electrode means.
  • the cell is preferably drained after the loading operation and an electrowinning solution, which is preferably specially made up for this purpose, is introduced for use in the electrowinning operation.
  • FIG. 2 is a diagrammatic section through a secondary cell of the invention which is an electro-forming cell
  • Figure 3 is a section on line 3 - 3 of Figure 2
  • Figure 4 is an enlarged detail of the first electrode of the cell of Figure 2
  • Figure 5 is a diagrammatic view of a switching arrangement for controlling the electrodes of the cell of Figure 2
  • Figure 6 is a view similar to Figure 2 of a first modified cell of the invention
  • Figure 7 is a view similar to Figure 2 of a second modified cell of the invention
  • Figure 8 is a horizontal section through the second modified cell
  • Figure 9 is a graph showing the residual gold concentration in the solution
  • Figure 10 is a similar graph on a log scale.
  • FIG. 1 there is shown the fluid flow diagram for an electro winning assembly 10 of the invention.
  • This particular electro winning arrangement 10 is intended to win gold from an eluate being a gold-bearing cyanide solution.
  • the electro winning assembly includes a primary electro winning tank array 100 and a set of secondary cells 200.
  • a liquid flow circuit and ancillary devices being a switch arrangement 400 and 450 being a lifting arrangement. All the abovementioned parts will be described more fully below.
  • the first electro-winning tank array 100 is in the form described in International
  • the tank array 100 comprises four tanks 102, of which only two 102.1 and 102.2, are shown; the tank 102.1 being shown in somewhat more detail.
  • Each tank 102 is provided with an inlet line 104 connected to a header feed line 106.
  • the inlet line 104 opens to the lower end of the tank 102 and is provided with a valve 108 controlling the connection to the header feed line 106.
  • Each tank 102 further has an outlet 110 at its upper end for the treated or spent solution.
  • This outlet 110 leads to a line 112 which splits into two lines 114 and 116, one (114) of which is connected to the inlet line 104 of the next tank 102 of the array and the other (116) of which is connected to a drain line 118.
  • Control valves 120 and 122 are provided respectively in the lines 114 and 116.
  • each tank 102 are up to four electro winning cells 124 each including a cathode assembly located above a discharge pipe 126.
  • An ultrasonic resonator 128 is provided for causing the gold particles formed on the cathodes to be shaken free and to be discharged through the discharge pipe 126 as a gold sludge.
  • the discharge pipes 126 are each connected through a valve 130 to a collector pipe 132.
  • the collector pipes 132 of each of the various tanks 102 are connected to their respective two feed lines 134 and 136. These two feed lines 134 and 136 are connected respectively through valves 138 and 140 to one of two inlets of two final electro winning cells 200 of the invention to be described. « _ . ,_, perennial_ _
  • Each secondary electro winning cell 200 has a central outlet leading to a recirculating line 142.
  • These re-circulating lines 142 are connected via valves 144 through a pump 146 which re-circulates the liquid from the cell 200 either (a) back to the tank 102; (b) to a holding tank or reservoir 148 through return lines 150 which each split into two sections 152 and 154 controlled respectively by valves 158 and 160 or
  • (c) delivers the spent solution to a drain line 188 via drain valves 178 and 180.
  • the reservoir 148 is connected back to the secondary cells 200 through two lines 164 and 166 each controlled by a valve 168 and 170 and leading to the second inlet to the secondary cell 200.
  • sub-assemblies 12 each comprising a first electro winning tank 102, a pair of main electro winning cells 200 and the associated piping, valves etc.
  • the secondary cell 200 is the secondary cell 200
  • the secondary cell 200 comprises a housing 204 (see Figure 2) having a base 206, a top part or roof 208 and a generally cylindrical body 210.
  • the body 210 of the housing 204 is provided at its lower and upper ends with flanges 212 and 214.
  • the lower flange 212 is connected by bolts 216 to the base 206.
  • the upper flange 214 is received within a ring clamp 218 into which is also received the edge of the top part 208 of the housing 204.
  • "O"-rings 220 and 222 are provided resoectively between the flanges 212 and 214 and the base 206 and top part 208 to seal for this purpose a shaft 224 is provided connected to an appropriate rotating motor (not shown).
  • a central outlet 226 provided in the base 206 connected to the recirculating line 142.
  • a further outlet 228 is provided in the base 206 for recovery of the gold form as will be described.
  • Two inlet ports 230 and 232 are provided in the sides 210 connected respectively to the lines 134 or 136 and 164 or 166.
  • Within the housing 204 is a central porous polypropylene cylinder 234 surrounding the outlet 226; first, second and third electrodes 236, 238 and 240 and collector electrodes 242.
  • a control or switch system 400 (see Figure 5) is provided for the electric connections 244, 246, 248 and 250 to connect them as will be described to the positive and negative terminals 402, 404 of a rectified power source 406 (which as described below may provide a pulsed power supply).
  • the porous polypropylene cylinder 234 serves as a filter for gold particles as will be described to inhibit or prevent them from escaping through the outlet 226.
  • the first, second and third electrodes 236, 238 and 240 are mounted on the base 206. Their upper ends are received in grooves in the top plate 208 in such a way that the top plate can rotate relative to them.
  • the first electrode 236 is a high surface area member. It comprises a dimensionally stable good electrical conductivity "meshed" spiral member 252 comprising expanded metal mesh or wire cloth and a "pored” high surface area material 254.
  • the spiral member 252 comprises titanium which is coated with iridium oxide.
  • the "pored" high surface area material 254 comprises porous carbon fibre felt.
  • pores high surface area material may however comprise inter alia stainless steel wool or graphite felt.
  • the titanium metal mesh and the porous fibre material are wound together in alternate spirals in the form of a "Swiss Roll” about the cylinder 234 (as is shown in Figure 4) and are in close physical and electrical proximity. Because of the close physical and electrical proximity of the mesh 252 and the "pored" high surface area material 254 there is a good electrical connection with the latter which improves its operation as an electrode.
  • Other "pored" high surface area materials that can be used are mentioned below.
  • the first electrode 236 is wound closely around the cylinder 234 so that the latter traps the metal sludge in such a way that it, the sludge, is in electrical contact with the electrode 236.
  • the second electrode 238 surrounds the first electrode 222 in coaxial spaced relationship therewith. It comprises a metal oxide-coated expanded titanium mesh.
  • the third electrode 240 also iridium oxide coated titanium mesh coaxially surrounds the second electrode 238 leaving a fairly large annular space 260 therebetween.
  • Each collector electrode 242 comprises a frusto conical polished stainless steel member 262 with a domed lower end 264 and a small cone angle. Its upper end 266 is cylindrical.
  • Each collector electrode 242 passes closely and in sealing relationship with an insulating block 268 through which it can be withdrawn as will be described.
  • the collector electrode 242 has a flange 270 above which is an upper extension 272 having a peripheral recess 274.
  • the electrical connection 250 is connected to the connector electrode 242 through the insulating block 268.
  • the electrical control system 400 includes first, second and third switches 408, 410 and 412. These may be electronic switches but for convenience they are shown as simple mechanical switches.
  • the switch 412 has a switch member 426 connected to the electrode 250. It has one terminal 428 connected to the negative terminal 404 of the power source 406. Its second terminal 430 is a blank terminal.
  • the switch members 414, 420 and 426 are connected together to move from a first position to a second position.
  • the switch member 414 In the first position, the switch member 414 is connected to the negative terminal 404 of the power source 406; the switch member 420 is connected to the positive terminal 402 of the power source 406 and the switch member 426 is connected to the blank terminal 430.
  • the switch member 414 In the second position, the switch member 414 is connected to the positive terminal 402; the switch member 420 is connected to the blank terminal 424; and the switch member 426 is connected to the switches are in the first position, the first and third electrodes 236 and 240 will act as cathodes and the second electrode 238 will act as an anode.
  • the collector electrodes 242 will be disconnected.
  • the first and third electrodes 236 and 240 When the switches are in their second position, the first and third electrodes 236 and 240 will act as anodes and the collector electrodes 242 will act as cathodes. The second electrode 238 will be disconnected. In a third position of the switch members the electrodes are all disconnected.
  • the lifting mechanism 450 comprises a pair of jaws 452 . These jaws 452 are at the end of a lazy tongs mechanism 454 actuated by a cylinder 456 to open and close the jaws 452 in such a way that they are able to engage in the recess 274 and thereby grip the collector electrode 242.
  • a lifting cylinder 458 serves to lift the cylinder 456 when the jaws 452 engage the electrode 242 and thus to lift this electrode 242.
  • the sub-assemblies 12 of the electro winning assembly 10 are each operated as follows:- gold loaded eluate comprising about 650 ppm of gold is fed into the tank 102.
  • the valves 130, 138, 144 and 158 are opened so that the solution can circulate through the tank 102 to one of the secondary cells 200.
  • the switches are moved into the first position.
  • the gold in the solution 170 in the tank 102 is deposited as particles on the cathode assemblies of the electro winning cells 124. Residual gold also comes out of solution in the secondary cell 200 and is deposited on the cathodes 236 and 240. After a substantial amount of gold has been deposited as aforesaid and the gold content of the particles off the cathode assemblies and the gold is conveyed as a gold sludge to the secondary cells 200. The gold particles from the gold sludge will now been trapped on the cathodes 236 and 240 and such further gold as may have been in solution is also so deposited.
  • the secondary cell 200 When the gold content of the solution has dropped to a sufficient level, the secondary cell 200 is drained of solution. It is then flushed with water and/or with a sodium hypochlorite solution. After flushing, a made up gold loaded electro forming solution consisting of 8 to 40 gram gold/litre is fed into the reservoir 148. The switches are moved to the second positions. The electro winning solution is now circulated through the secondary cell and reservoir 148 via lines 142, 150, 154 and 164. The gold on the first and third electrodes 236 and 240 (which now act as anodes) in passed into solution and then deposited on to the polished stainless steel member 262 of each of the collector electrodes 242.
  • the gold builds up on the member 262 to form an integral stable gold electro form 276 which because of the shape of the member 262 is in the form of a thimble.
  • the switches are moved in into their third, isolated, position.
  • the cell is then drained with the elect reforming solution recovered for re-use.
  • the electro-forms 276 are now recovered as follows.
  • the jaws 452 engage the collector electrode 242 and the cylinder 458 is now actuated to lift the electrode 242 a small amount, which may be as little as 1 mm.
  • "thimble" 276 engages the block 268 and is thus moved off the steel part 262 and falls through the opening 228 from whence it is conveyed to a collection position (not position and the jaws 452 release the collector electrode 242.
  • the top member 208 is now rotated by the rotating motor until the next collector electrode 242 is located above the opening 228 so that it may be lifted by the lifting mechanism 450 as described above.
  • the cell is again flushed, reconnected to the electro winning tank 102 the operation is repeated.
  • the other secondary cell When one of the secondary cells is in the metal collection phase and in the circulating mode with the tank 102, the other secondary cell is in the stripping/electroforming mode and the two cells operate alternately.
  • This cell 300 comprises a housing 310 having the same liquid connections as the housing 210.
  • a porous polypropylene cylinder 312 which extends from the top plate 314 to the base 316 of the housing 310.
  • a first electrode 318 is wound on to this cylinder 312 in a manner identical to the first 236 of the first embodiment.
  • Centrally located within the cylinder 312 is a cylindrical titanium rod 320 which is coated with ruthenium oxide.
  • the rod 320 is carried by a central conical insert 322 in the top plate 314 with "O"-rings 324 and 326 to provide adequate sealing between the insert 322 and the rod 320 and top plate 314 respectively.
  • Electric connectors 328 and 340 are provided so that (a) the first electrode 318 can act as a cathode during the electro winning operation (when the solution is circulating to the tank) and as an anode during the plating operation (when the solution is circulating to the reservoir) and (b) the rod acts as an anode during the
  • the modified secondary cell 300 operates within the sub-assembly 12 in the analogous manner to that described above.
  • the gold is deposited on the rod 320 which is now cathodic.
  • the rod 320 is fully loaded it is removed from the secondary cell 300 and subjected, at a suitable location, to an electro-refining operation. When stripped of gold, it is returned to the secondary cell 300 for further operations. It will be understood of course that there will be a number of such rods 320 provided to ensure continuous operation of the secondary cell.
  • the secondary cell 300 may also be used, especially in small-scale field operations, to refine gold in situ. This is done as follows. After the high surface area first electrode 318 has been loaded with gold, the cyanide solution is drained from the cell and recycled to its reservoir. The cell 300 is then flushed with a water/sodium hypochlorite solution to remove vestiges of cyanide in the cell and on the electrodes. The cell 300 is then filled with a gold chloride/hydrochloric acid solution. The first electrode 318 is now made anodic with respect to the electroforming rod 320.
  • Essentially pure gold is electroformed on to the rod 320. Impurities such as silver, platinum group metals and lead are precipitated out as a metal sludge, which can be conveyed to a suitable location for refining, if desired.
  • the central electroplating rod 320 may be replaced by an electro forming electrode or mandrel such as the collector electrode 262 of the embodiment described with reference to Figure 2. If desired, even more complex electro forming electrodes or mandrels may be provided instead of the rod 320.
  • a second modified secondary cell may be provided instead of the rod 320.
  • a second modified secondary cell 600 is shown in Figures 7 and 8. It comprises a generally parallelipipedal housing 602 having sides 604 and 606, ends 608 and 610, a base 612 and a top plate 614. Three central form discharge ports 616 are provided in the base 612 in the position to be described. Two inlet ports 618 are provided at the ends of one side 604 and an outlet port 619 is provided centrally of the other side 606.
  • Porous polypropylene sheets 620 on either side of the outlet port 619 extend from the base 612 to the top plate 614 and from one side to the other to serve as filters in the same way as the filter 234.
  • a pair of first electrodes 622 extending the whole height and width of the housing 602 between the sides 604 and 606 are provided respectively on the outside of each sheet 620 and in close proximity thereto so that so that each filter sheet traps the metal sludge in such a way that it, the sludge, is in electrical contact with the electrode 622.
  • Each electrode comprises a pair of identical flat metal meshes 624 clamping closely between them a high surface area material 626.
  • Each mesh 624 comprises titanium which is coated with iridium oxide.
  • the high surface area material 626 comprises any one of the materials described above.
  • each of the first electrodes 622 and in spaced relation thereto are identical second and third electrodes 628.
  • These electrodes 628 comprise a metal oxide-coated expanded titanium mesh. They are located inside of the inlet ports 618.
  • collector electrodes 630 There are three equi-spaced collector electrodes 630 depending from the ton plate 614 of the housing 602 being located on a line mid- way between the ends 608 electrodes 242 described above.
  • the form discharge ports 616 are aligned with the electrodes 242.
  • Lifting means are provided to lift the collector electrodes 630 for the same purpose as described above.
  • Electric connections 632 are provided for the electrodes in a manner analogous to that described for the secondary cell 200.
  • An electrical control system (not shown) similar to the system 400 is provided. It comprises three switches.
  • the first switch connects the first electrodes 622 either to the positive or negative terminals of a pulsing DC electric source.
  • the second switch (i) connects the second and third electrodes 628 to the positive terminal when the first electrodes are connected to the negative terminal and (ii) isolates these electrodes 628 when the first electrodes 622 are connected to the positive terminal.
  • the third switch (i) connects the collector electrodes 630 to the negative terminal when the first electrodes are connected to the positive terminal, and (ii) isolates these collector electrodes 630 when the first electrodes 622 are connected to the negative terminal.
  • the secondary cell 600 operates in the same manner as the secondary cell 200. After the electroforms or thimbles are formed, the cell 600 is drained. The lifting mechanism now lift the collector electrodes 630 to strip them of the electro forms which now are collected through the drain ports 616. Size of the secondary cells and collector electrodes.
  • the various secondary cells 200, 300 and 600 may have any capacity as desired.
  • the cell 200 has a capacity of about 10 litres and the cell 300 has a capacity of about 2 litres.
  • the cell 600 has a capacity of about 12 litres.
  • the collector electrodes 242 each have an axial length of about 200 mm and an average diameter of 17 mm.
  • a seventh example deals with the electro forming operation. Only one collector electrode 242 was connected to the switching circuit 400 i.e. the gold was electro formed on only one collector electrode and this electrode was masked off so that the gold would be electro formed on a section of the collector electrode. Further as This was necessary because of the limited amount of gold present.
  • the cathode current density is expressed in terms of the geometrical, not actual, surface area of the high surface area cathode i.e. the mesh and the high surface area material, and of the collector cathode in example 7.
  • the plating power supply was a direct current supply.
  • Example 1 In this example, solution 1A was used with a starting gold content of 103 ppm. The solution was heated to 21 °C. The voltage applied was 6,5 volts. The current density was 2 A/dm 2 . The solution was circulated at 32 litres / minute. The total time of the run was 360 minutes.
  • Example 2 In this example, solution 2 A which is identical to solution 1A was used in a 240 minute run. The average temperature of the run was 43 °C. The average voltage was 4,2 volts. The current density and flow rate were the same as in example 1.
  • Example 3 In this example a solution 3A containing 349 ppm of gold was used in a run of 280 minutes. The average temperature of the solution of the run was 43 °C. The average voltage 4,8 volts. The average current density was 4 A/dm 2 and the flow rate 32 litres per minute.
  • Example 4 A solution 4A containing 342 ppm gold was subjected to a run of 315 minutes. The solution was heated to 34 °C and power was supplied at 3.8V and 2 A/dm 2 . The flow rate was 16 litres per minute.
  • a solution 5B containing 895 ppm gold was subject to a run of 305 minutes.
  • the solution was heated to 44 °C.
  • the same power supply as mentioned in example 4 was provided.
  • the flow rate was 32 litres per minute.
  • Example 6 A solution 6B containing 164 ppm gold was subject to a run of 240 minutes. The solution was heated to 45 °C. The average voltage 4.5 volts. The average current density was 2 A/dm 2 and the flow rate 32 litres per minute.
  • Example 7 The cell 200 was used to produce an electro form.
  • the high surface area electrode 236 was loaded with gold as described in the previous examples. By calculation the total amount of gold amounted to 32 grams of gold.
  • the electroforming solution was introduced into the circuit.
  • the electroforming solution used was 18 litres of a gold eluate solution from mine B, which contained about 200 ppm gold.
  • the high surface area electrode was made anodic relative to the rr.llector electrode.
  • the power was supplied as a pulse supply being twenty current density of about 0,3 A/dm 2 . Because of the low concentration of electro forming solution, the operation was very lengthy taking approximately forty eight hours.
  • the high surface area electrode was stripped of gold and a matt self sustaining gold alloy tapered tube 276 of gold was formed weighing about 8 grams. It had an average internal diameter of 16 mm, an axial length of about 30 mm and a wall thickness of approximately 0,3 mm.
  • Example 5 in which the undiluted head sample was used, the initial gold concentration analyzed at 895 ppm gold, as against about 659 ppm gold for the original head sample from gold mine B. This discrepancy may again be explained by the re-dissolution of finely dispersed gold present on the electrodes 236 and 238. This gold would be there from previous examples and as the circulating cyanide solution was pre-heated to operating temperature over several hours before the commencement of Example 5, that gold would re- dissolve and register as a higher value than would have been anticipated.
  • each thimble would typically have a wall thickness of 2 mm and a mass of 450 grams. Because of the impracticability of using such a solution in the presence of such a small amount of electro-won gold - any effects would be swamped
  • the electroforming solution used was, as described, 18 litres of a gold eluate solution from mine B, which contained about 200 ppm gold with the additives mentioned.
  • the electro form thus produces appeared dark friable and rough.
  • the change to a pulsed current supply as mentioned improved the quality of the electroform produced.
  • the electrode which acts as an anode during the loading operation may comprise expanded metal mesh typically of stainless steel or of titanium coated with iridium oxide, ruthenium oxide, or similar such as tantalum oxide.
  • the electrode which acts as a cathode during the loading operation i.e. the electrodes 236 and 240 in the embodiment of Figure 2, the electrode 318 in the
  • each such electrode may wire cloth each coated with iridium oxide, ruthenium oxide, or similar such as tantalum oxide, or else stainless steel expanded mesh or wire cloth, and/or (b) and the "pored" material is reticulated vitreous carbon, carbon or graphite felt, coated titanium wool or coated open cell titanium foam, or similar materials such as packed carbon granules.
  • each such electrode comprises both these two types of material.
  • this meshed member of the electrode is of this construction and in particular because it is coated as aforesaid it can be used both as cathode and as an anode in prolonged service.
  • the use of the "pored" material is of importance because of its very high surface are enabling it to remove metals at very low concentrations.
  • Electrodes may be of any desired and applicable shape in addition to the shapes described above.
  • the collector electrodes may comprise polished stainless steel, as described, or titanium or which are of ruthenium oxide coated titanium, when required as electro-refining anodes in a chloride medium. These electrodes, which as described are preferably conical in shape to facilitate electroform removal, may be of other shapes if desired.
  • the filter material may be of porous polypropylene, as described, but may be any other suitable material.
  • the secondary cells may be used in certain circumstances without there being a primary tank array, i.e. the secondary cells will receive the eluate direct from the leaching operation.
  • electro winning arrangements as described above may be used for electro winning other metals such as silver, copper, nickel, zinc, and cobalt, and, by separating the anode and cathode compartments by means of a suitable membrane, the platinum group metals.
  • the sizes of the housings and the collector electrodes may vary as desired. Where other metals are electro won the electrowinning solution may comprise the anions e.g. sulphate of the metal being won. 5976

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Abstract

Cette invention se rapporte à un système d'extraction électrolytique, qui comprend trois électrodes cylindriques coaxiales: (i) une première électrode interne (236) qui sert de cathode pendant la phase de chargement du métal et d'anode pendant la phase d'extraction électrolytique, (ii) une seconde électrode intermédiaire (238) qui sert d'anode pendant la phase de chargement du métal, et (iii) une troisième électrode externe (240) qui est connectée à la première électrode et qui sert de première électrode. Un ensemble d'électrodes collectrices (276) sont placées entre la seconde et la troisième électrode et servent de cathodes pendant la phase d'extraction électrolytique, où des dépôts de métal se forment par galvanoplastie. Ce système est principalement conçu pour l'extraction électrolytique d'or, mais il peut également être utilisé avec d'autres métaux. Diverses modifications de la cellule sont décrites.
PCT/ZA2003/000145 2002-10-04 2003-10-03 Extraction electrolytique de metaux Ceased WO2004031453A1 (fr)

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AU2003275505A AU2003275505A1 (en) 2002-10-04 2003-10-03 Electowinning of metals

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ZA2002/7977 2002-10-04

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Cited By (12)

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WO2012087398A1 (fr) * 2010-12-23 2012-06-28 Ge-Hitachi Nuclear Energy Americas Llc Systèmes de distribution d'énergie d'anode-cathode et procédés destinés à les utiliser pour une réduction électrochimique
US8598473B2 (en) 2011-12-22 2013-12-03 Ge-Hitachi Nuclear Energy Americas Llc Bus bar electrical feedthrough for electrorefiner system
US8746440B2 (en) 2011-12-22 2014-06-10 Ge-Hitachi Nuclear Energy Americas Llc Continuous recovery system for electrorefiner system
US8771482B2 (en) 2010-12-23 2014-07-08 Ge-Hitachi Nuclear Energy Americas Llc Anode shroud for off-gas capture and removal from electrolytic oxide reduction system
US8882973B2 (en) 2011-12-22 2014-11-11 Ge-Hitachi Nuclear Energy Americas Llc Cathode power distribution system and method of using the same for power distribution
US8900439B2 (en) 2010-12-23 2014-12-02 Ge-Hitachi Nuclear Energy Americas Llc Modular cathode assemblies and methods of using the same for electrochemical reduction
US8945354B2 (en) 2011-12-22 2015-02-03 Ge-Hitachi Nuclear Energy Americas Llc Cathode scraper system and method of using the same for removing uranium
US8956524B2 (en) 2010-12-23 2015-02-17 Ge-Hitachi Nuclear Energy Americas Llc Modular anode assemblies and methods of using the same for electrochemical reduction
US8968547B2 (en) 2012-04-23 2015-03-03 Ge-Hitachi Nuclear Energy Americas Llc Method for corium and used nuclear fuel stabilization processing
US9017527B2 (en) 2010-12-23 2015-04-28 Ge-Hitachi Nuclear Energy Americas Llc Electrolytic oxide reduction system
US9150975B2 (en) 2011-12-22 2015-10-06 Ge-Hitachi Nuclear Energy Americas Llc Electrorefiner system for recovering purified metal from impure nuclear feed material
WO2023175570A1 (fr) * 2022-03-16 2023-09-21 Flsmidth A/S Système et procédé de commande ou d'élimination de dépôts durs sur des cathodes d'extraction électrolytique

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US4039407A (en) * 1975-01-20 1977-08-02 Electrolyte Services Limited Method for electrolytic silver recovery
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US4585539A (en) * 1982-08-17 1986-04-29 Technic, Inc. Electrolytic reactor

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8956524B2 (en) 2010-12-23 2015-02-17 Ge-Hitachi Nuclear Energy Americas Llc Modular anode assemblies and methods of using the same for electrochemical reduction
CN103261488A (zh) * 2010-12-23 2013-08-21 通用电气-日立核能美国有限责任公司 阳极-阴极功率分配系统和使用其用于电化学还原的方法
US9920443B2 (en) 2010-12-23 2018-03-20 Ge-Hitachi Nuclear Energy Americas Llc Modular cathode assemblies and methods of using the same for electrochemical reduction
US8636892B2 (en) 2010-12-23 2014-01-28 Ge-Hitachi Nuclear Energy Americas Llc Anode-cathode power distribution systems and methods of using the same for electrochemical reduction
CN103261488B (zh) * 2010-12-23 2016-09-07 通用电气-日立核能美国有限责任公司 阳极-阴极功率分配系统和使用其用于电化学还原的方法
US8771482B2 (en) 2010-12-23 2014-07-08 Ge-Hitachi Nuclear Energy Americas Llc Anode shroud for off-gas capture and removal from electrolytic oxide reduction system
US9017527B2 (en) 2010-12-23 2015-04-28 Ge-Hitachi Nuclear Energy Americas Llc Electrolytic oxide reduction system
US8900439B2 (en) 2010-12-23 2014-12-02 Ge-Hitachi Nuclear Energy Americas Llc Modular cathode assemblies and methods of using the same for electrochemical reduction
WO2012087398A1 (fr) * 2010-12-23 2012-06-28 Ge-Hitachi Nuclear Energy Americas Llc Systèmes de distribution d'énergie d'anode-cathode et procédés destinés à les utiliser pour une réduction électrochimique
US8945354B2 (en) 2011-12-22 2015-02-03 Ge-Hitachi Nuclear Energy Americas Llc Cathode scraper system and method of using the same for removing uranium
US8882973B2 (en) 2011-12-22 2014-11-11 Ge-Hitachi Nuclear Energy Americas Llc Cathode power distribution system and method of using the same for power distribution
US9150975B2 (en) 2011-12-22 2015-10-06 Ge-Hitachi Nuclear Energy Americas Llc Electrorefiner system for recovering purified metal from impure nuclear feed material
US8746440B2 (en) 2011-12-22 2014-06-10 Ge-Hitachi Nuclear Energy Americas Llc Continuous recovery system for electrorefiner system
US8598473B2 (en) 2011-12-22 2013-12-03 Ge-Hitachi Nuclear Energy Americas Llc Bus bar electrical feedthrough for electrorefiner system
US8968547B2 (en) 2012-04-23 2015-03-03 Ge-Hitachi Nuclear Energy Americas Llc Method for corium and used nuclear fuel stabilization processing
WO2023175570A1 (fr) * 2022-03-16 2023-09-21 Flsmidth A/S Système et procédé de commande ou d'élimination de dépôts durs sur des cathodes d'extraction électrolytique

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