Classifications

• • 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
  • C25C1/22—Electrolytic production, recovery or refining of metals by electrolysis of solutions of metals not provided for in groups C25C1/02 - C25C1/20
• • 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
  • C25C1/12—Electrolytic production, recovery or refining of metals by electrolysis of solutions of copper

Definitions

• the subject of the present invention is a novel method of the electrolytic isolation of arsenic from waste electrolytes from the electrorefining of copper, a method of preparing electrolyte by its decopperisation as well as a method of isolation of arsenic from copper industry electrolytes with their prior decopperisation .
• arsenic is a significant component of Polish copper concentrates. Annually, material processing is supplemented by about 2500 tons of arsenic. According to the same literature source, there are at least two material streams from which the reclamation and stabilization of arsenic are not fully mastered.
• the first subject of the present invention is a method of electrolytic isolation of arsenic from a post-refining electrolyte characterised in that it is embodied using a single- stage potentiostatic arsenic isolation process, preferably on a steel cathode, in the cathode potential range of from -1.20 V to -1.70 V in relation to the anode, preferably of acid-resistant steel, wherein the electrolyte is not chemically processed.
• the isolation is conducted without any chemical processing of the electrolyte which, for contrast, is required in the solvent extraction (SX) as used at present in the isolation of copper salts from the post-refinement solution.
• a method according to the present invention is characterised in that the electrodeposition is conducted at room temperature from 18°C to 50°C, preferably from 18°C to 30°C.
• a method according to the present invention is characterised in that the electrodeposition process makes use of an anode of a lead alloy, or based on titanium oxide and iridium wherein the cathode and anode surface areas are comparable.
• the example anodes are already used in the galvanic industry in the electrodeposition of copper. More preferably a method according to the present invention is characterised in that the electrodeposition process is conducted using an anode of acid- resistant steel and then the anode surface area is at least 5- fold that of the cathode. Equally preferably, a method according to the present invention is characterised in that the electrodeposition is conducted using a cathode of acid-resistant steel or of copper. Most preferably, a method according to the present invention is characterised in that the process of electrodeposition is conducted with constant circulation of the electrolyte or with electrolyte mixing.
• the second subject of the present invention is a method of decopperisation of a post-refining electrolyte, characterised in that it is embodied using a single-stage potentiostatic process isolation of copper on a cathode with a cathode potential range of from -1.00 V to -1.50 V in relation to the acid-resistant steel anode, wherein the electrolyte is not subjected to. chemical processing.
• Equally preferably a method according to the present invention is characterised in that the electrodeposition process is conducted at room temperature from 18°C to 50°C, preferably from 18°C to 30°C.
• a method according to the present invention is characterised in that the electrodeposition process makes use of a lead alloy anode, or one based on titanium oxide and iridium, wherein the surface areas of the cathode and anode are comparable. More preferably, a method according to the present invention is characterised in that the electrodeposition process is conducted using an acid-resistant steel anode, wherein the anode surface area is at least 5-fold greater than the cathode surface area. W the next preferable embodiment of the present invention, the method is characterised in that the electrodeposition process is conducted using a cathode of acid-resistant steel or of copper. Also preferably, a method according to the present invention is characterised in that the electrodeposition process is conducted with constant electrolyte circulation or mixing.
• the third subject of the present invention is a method of electrolytic isolation of arsenic from a post-refining electrolyte, characterised in that it encompasses
• the present invention relates to a method of electrolytic and potentistatic production of arsenic from electrolytes, in which the concentration of copper is about 1 mg/1.
• -a post-refining electrolyte is decopperised to a concentration of about 1 mg/1, preferably according to the second subject of the present invention
• the cathode is exchanged as well as increasing the cathode potential by at least -200 mV such that the isolation of arsenic proceeds at a commercially effective rate
• the deposited arsenic is such that it may be a commercial product, and not a copper-arsenic sponge which is a troublesome waste product in need of further processing,
• the arsenic deposited during the above process is finally removed from the material cycle and does not require further processing or manipulation, -during the potentiostatic isolation of arsenic the toxic arsenous gas AsH 3 is not produced.
• the process of decopperisation via the electrodeposition of copper from post- refining electrolytes is carried out using potentiostatic electrolysis: potentiostatic electrolysis with a cathode potential range of from -1.20 V to -1.70 V, in relation to an acid-resistant steel anode, wherein the time of electrolysis is dependent on an initial concentration of arsenic, the final concentration of arsenic that is to be achieved, the applied cathode potential, electrolyte mixing or flow rate as well as temperature. If the value of the resistance in Ohms IR is negligible, the range of cathode potentials in relation to the acid-resistant steel anode is from -1.20 V to -1.45 V. Due to the differing construction of the electrolysers , and the industrial electrolytes used (of varying conductivity and resistance) , the potential drop entailed by the ohmic resistance can be from -0.2 to -0.5 V
• the maximum value of the applied cathode potential is -1.70 V.
• the present invention defined in the second subject of the present invention, has an advantage over the above-defined methods in that the proposed decopperisation method is based solely on potentistatic electrodeposition, wherein:
• the post-refining electrolyte is decopperised to a concentration level of about 1 ppm (lmg/dm 3 , thus the concentration of copper in the decoppered solution is at least 200 times smaller than in the presently used process) which has an economic, technical and ecological significance;
• the cathodic copper produced throughout the concentration range thus from about 50 g/dm 3 to 1 mg/dm 3 has a commercial purity, meaning >99.9% by mass;
• Example 1 In an electrochemical vessel thermoregulated to 25°C there is an indicator electrode of steel plate with a surface area of about 2.5 cm2. which is the cathode, as well as a reference electrode 10 (anode) in the form of a steel plate with a surface area of about 50 cm2 and a thickness of 0.15 cm.
• the vessel is filled with an industrial electrolyte after a presently used industrial decopperisation, and then according to the decopperisation method defined in the second subject of the present invention (example 3 and 4), therefore of the following composition: 0.001 g/dm 3 Cu, 170 g/dm 3 H 2 S0 4 as well as 0.102 g/dm 3 Fe, 0.147 g/dm 3 Sb, 0.032 g/dm 3 Co, 5,1 g/dm 3 Ni, as well as 2.9 g/dm 3 As.
• the electrodes are connected to a measurement device - a commercially available galvanostat /potentiostat which can be programmed to perform an electrolysis. During the electrolysis we measure current changes dependent on electrolysis duration. The size of the recorded current is connected to the changes in the concentration of arsenide ions in solution. The solution is not mixed.
• the vessel is filled with an industrial electrolyte after a presently used industrial decopperisation, and then according to the decopperisation method defined in the second subject of the present invention (example 3 and 4), therefore of the following composition: 0.001 g/dm 3 Cu, 170 g/dm 3 H 2 S0 4 as well as 0.102 g/dm 3 Fe, 0.147 g/dm 3 Sb, 0.032 g/dm 3 Co, 5,1 g/dm 3 Ni, as well as 2.9 g/dm 3 As.
• the electrodes are connected to a measurement device - a commercially available galvanostat/potentiostat which can be programmed to perform an electrolysis.
• a measurement device - a commercially available galvanostat/potentiostat which can be programmed to perform an electrolysis.
• the electrolysis we measure current changes dependent on electrolysis duration.
• the size of the recorded current is connected to the changes in the concentration of arsenide ions in solution.
• the vessel is filled with an industrial electrolyte after an industrial decopperisation according to a presently used decopperisation method, meaning galvanostatic cascade deposition, with the following composition: 0.102 g/dm 3 Cu, 170 g/dm 3 H 2 S0 4 as well as 0.102 g/dm 3 Fe, 0.147 g/dm 3 Sb, 0.032 g/dm 3 Co, 5,1 g/dm 3 Ni, as well as 2.9 g/dm 3 As.
• the electrodes are connected to a measurement device - a commercially available galvanostat/potentiostat which can be programmed to perform an electrolysis.
• the electrolysis we measured current changes dependent on the progress of the electrolysis.
• the size of the recorded current is connected to the changes in the concentration of copper ions in solution.
• the solution is mixed at a rate of 50 RPM.
• the potentiostatic electrolysis parameters are:
• the resulting cathodic copper thus has a purity of > 99.9% by mass.
• the solution was analyzed using absorption atomic spectroscopy and we observed that the concentration of copper is 0.004 g/dm 3 (4 ppm) .
• an indicator electrode of steel plate with a surface area of about 2.5 cm 2 which is the cathode, as well as a reference electrode (anode) in the form of a copper plate with a surface area of about 50 cm 2 and a thickness of 0.15 cm.
• the vessel is filled with an industrial electrolyte after an industrial decopperisation according to a presently used decopperisation method, meaning galvanostatic cascade deposition, with the following composition: 0.102 g/dm 3 Cu, 170 g/dm 3 .
• the electrodes are connected to a measurement device - a commercially available galvanostat/potentiostat which can be programmed to perform an electrolysis.
• a measurement device a commercially available galvanostat/potentiostat which can be programmed to perform an electrolysis.
• the electrolysis we measured current changes dependent on the progress of the electrolysis. The size of the recorded current is connected to the changes in the concentration of copper ions in solution. The solution is not mixed.
• the resulting cathode copper thus has a purity of >99.9% by mass.
• the solution was analyzed using absorption atomic spectroscopy and observed that the concentration of copper is 0.002 g dm-3 (2 ppm) .

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• 2012
  • 2012-10-19 EP EP12795068.1A patent/EP2769004A1/en not_active Withdrawn
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  • 2012-10-19 CN CN201280063161.4A patent/CN104204305A/zh active Pending
  • 2012-10-19 WO PCT/IB2012/055717 patent/WO2013057700A1/en active Application Filing
• 2014
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