The invention relates to a method for electrowinning a metal from an electrolyte in an electrowinning cell that comprises an electrolysis tank, one or more anodes, and one or more cathodes, which anodes and cathodes are housed in the electrolysis tank. The method comprises supplying sulfur dioxide to the anode to depolarize the anode process and to reduce the energy consumption of the electrowinning cell.

The invention relates to a method for electrowinning a metal from an electrolyte in an electrowinning cell that comprises an electrolysis tank, one or more anodes, and one or more cathodes, which anodes and cathodes are housed in the electrolysis tank. The method comprises supplying sulfur dioxide to the anode to depolarize the anode process and to reduce the energy consumption of the electrowinning cell.

The invention relates to a combined electrolytic system for precipitating different types of metals (copper, zinc, nickel, cadmium, cobalt, silver, gold) and regenerating reagents for the leaching of metal sulphurs from solutions from leaching in a sulphuric-oxidising or hydrochloric-oxidising environment, including a process that permits the combining of the current reduction processes followed by oxidising processes which are complex and potentially dangerous from an environmental point of view, thereby preventing the risky transportation of dangerous substances, loading and unloading operations, storage and manipulation of toxic materials, and reducing the environmentally contaminating waste, producing a commercial-quality cathodic product and a solution that is re-used in the leaching process. The system comprises a membrane cell device (3) that is connected via ducts and valves to one or more oxidising agent tanks (7), to one or more anodic solution tanks (6) and to one or more cathodic solution tanks (2), wherein said membrane device (3) is formed by one or more cathodic compartments (4) and by one or more anode compartments (5), wherein each of the cathodic compartment(s) (4) is/are separated from each of the anode compartment(s) (5) by a membrane for selective and uni-directional ion exchange.

A method of recovering metals from electronic waste comprises providing a powder comprising electronic waste in at least a first reactor and a second reactor and providing an electrolyte comprising at least ferric ions in an electrochemical cell in fluid communication with the first reactor and the second reactor. The method further includes contacting the powders within the first reactor and the second reactor with the electrolyte to dissolve at least one base metal from each reactor into the electrolyte and reduce at least some of the ferric ions to ferrous ions. The ferrous ions are oxidized at an anode of the electrochemical cell to regenerate the ferric ions. The powder within the second reactor comprises a higher weight percent of the at least one base metal than the powder in the first reactor. Additional methods of recovering metals from electronic waste are also described, as well as an apparatus of recovering metals from electronic waste.

A method of recovering metals from electronic waste comprises providing a powder comprising electronic waste in at least a first reactor and a second reactor and providing an electrolyte comprising at least ferric ions in an electrochemical cell in fluid communication with the first reactor and the second reactor. The method further includes contacting the powders within the first reactor and the second reactor with the electrolyte to dissolve at least one base metal from each reactor into the electrolyte and reduce at least some of the ferric ions to ferrous ions. The ferrous ions are oxidized at an anode of the electrochemical cell to regenerate the ferric ions. The powder within the second reactor comprises a higher weight percent of the at least one base metal than the powder in the first reactor. Additional methods of recovering metals from electronic waste are also described, as well as an apparatus of recovering metals from electronic waste.

A method of recovering metals from electronic waste comprises providing a powder comprising electronic waste in at least a first reactor and a second reactor and providing an electrolyte comprising at least ferric ions in an electrochemical cell in fluid communication with the first reactor and the second reactor. The method further includes contacting the powders within the first reactor and the second reactor with the electrolyte to dissolve at least one base metal from each reactor into the electrolyte and reduce at least some of the ferric ions to ferrous ions. The ferrous ions are oxidized at an anode of the electrochemical cell to regenerate the ferric ions. The powder within the second reactor comprises a higher weight percent of the at least one base metal than the powder in the first reactor. Additional methods of recovering metals from electronic waste are also described, as well as an apparatus of recovering metals from electronic waste.

A method of recovering metals from electronic waste comprises providing a powder comprising electronic waste in at least a first reactor and a second reactor and providing an electrolyte comprising at least ferric ions in an electrochemical cell in fluid communication with the first reactor and the second reactor. The method further includes contacting the powders within the first reactor and the second reactor with the electrolyte to dissolve at least one base metal from each reactor into the electrolyte and reduce at least some of the ferric ions to ferrous ions. The ferrous ions are oxidized at an anode of the electrochemical cell to regenerate the ferric ions. The powder within the second reactor comprises a higher weight percent of the at least one base metal than the powder in the first reactor. Additional methods of recovering metals from electronic waste are also described, as well as an apparatus of recovering metals from electronic waste.

A process has been developed in order to recover and recycle the metals present in spent batteries, including alkaline spent batteries alone or mixed with other types of spent batteries. This method shows a good potential in terms of metals recoveries efficiencies and economic feasibility. Firstly, the spent batteries are crushed (optionally after having been frozen in the case of spent batteries of mixed types). Then, the undesirable parts (plastics, steel cases, papers, etc.) are removed by screening. The collected powder, containing the metals, is mixed with a solution of sulfuric acid in the presence of a reducing agent. The solid/liquid separation is carried out by filtration and the leachate is purified in order to selectively recover the metals. The purification steps consist of: a) recovering Zn by solvent extraction followed by an electrowinning process; b) simultaneously recovering Mn and Cd by solvent extraction process; c) selectively recovering Cd from the mixture solution of Cd and Mn by electrowinning process; d) precipitating Mn from a pure solution of MnSO.sub.4 in a carbonate form; e) removing the impurities present in the effluent by solvent extraction in order to obtain a pure NiSO.sub.4 solution; f) precipitating Ni from a NiSO.sub.4 solution in a carbonate form.

A process has been developed in order to recover and recycle the metals present in spent batteries, including alkaline spent batteries alone or mixed with other types of spent batteries. This method shows a good potential in terms of metals recoveries efficiencies and economic feasibility. Firstly, the spent batteries are crushed (optionally after having been frozen in the case of spent batteries of mixed types). Then, the undesirable parts (plastics, steel cases, papers, etc.) are removed by screening. The collected powder, containing the metals, is mixed with a solution of sulfuric acid in the presence of a reducing agent. The solid/liquid separation is carried out by filtration and the leachate is purified in order to selectively recover the metals. The purification steps consist of: a) recovering Zn by solvent extraction followed by an electrowinning process; b) simultaneously recovering Mn and Cd by solvent extraction process; c) selectively recovering Cd from the mixture solution of Cd and Mn by electrowinning process; d) precipitating Mn from a pure solution of MnSO.sub.4 in a carbonate form; e) removing the impurities present in the effluent by solvent extraction in order to obtain a pure NiSO.sub.4 solution; f) precipitating Ni from a NiSO.sub.4 solution in a carbonate form.

The present invention provides a polymer based bulk conducting electrodes. These electrodes have several advantages over the conventional screen printed and coated electrodes. The present invention also provides biodegradable variant of these electrodes. Such electrode are found comparable to the conventional noble metal electrode and glassy carbon electrode in various electrochemical techniques like cyclic voltammetry of different redox couple, amperometric sensing of hydrogen peroxide, stripping voltammetry of lead (II) ion, electrodeposition of zinc and electropolymerization of aniline in aqueous medium.