Oxide electrowinning process

Chemically, the oxide electrowinning process involves chemical reachon, dissolution, electrolysis, and precipitahon. But in theory, it can all be achieved in a single pot or batch of molten salt. This should provide the compactness and simplicity of equipment requirements, even though it must be operated completely within a shielded, inert-atmosphere hot cell. In testing of this process, MOX deposits up to 2.7 kg have been achieved with a composition of 30% Pu/70% U. 

Copper. Copper is economically extracted by smelting of a chalcopyrite concentrate. A copper electrowinning process was developed commercially in 1912 for the treatment of lean ores. It is also suitable for treatment of copper oxide or sulfate obtained by roasting of the concentrate. 

In the case of molten salts, the functional electrolytes are generally oxides or halides. As examples of the use of oxides, mention may be made of the electrowinning processes for aluminum, tantalum, molybdenum, tungsten, and some of the rare earth metals. The appropriate oxides, dissolved in halide melts, act as the sources of the respective metals intended to be deposited cathodically. Halides are used as functional electrolytes for almost all other metals. In principle, all halides can be used, but in practice only fluorides and chlorides are used. Bromides and iodides are thermally unstable and are relatively expensive. Fluorides are ideally suited because of their stability and low volatility, their drawbacks pertain to the difficulty in obtaining them in forms free from oxygenated ions, and to their poor solubility in water. It is a truism that aqueous solubility makes the post-electrolysis separation of the electrodeposit from the electrolyte easy because the electrolyte can be leached away. The drawback associated with fluorides due to their poor solubility can, to a large extent, be overcome by using double fluorides instead of simple fluorides. Chlorides are widely used in electrodeposition because they are readily available in a pure form and... 

The first electrolytic nickel refinery plant, treating nickel metal anodes, was built by Hybinette in Kristiansand, Norway, in 1910, and this plant was acquired by Falconbridge in 1928. INCO developed electrorefining of nickel sulfide matte anodes in the 1950s. In a typical electrowinning process, the raw material is first smelted to a matte and then leached in a sulfate or chloride solution. The sulfur of the raw material is oxidized to insoluble elemental sulfur or soluble sulfate. The nickel contents of the mattes treated hydrometallurgically are in the... 

The Zincor process is based on the roast-leach-electrowinning process. The zinc sulphide concentrate is roasted in four Lurgi fiuo-solids roasters to produce zinc oxide and sulphur dioxide gas. The SO2 gas is fed to two Monsanto double absorption acid plants. 

After the copper and cobalt removal the PLS contains now almost purely NiS04(aq). The nickel can be recovered as cathodes from electrowinning or nickel powder from the hydrogen reduction In the electrowinning process, nickel is precipitated from a nickel sulphate solution into metallic form by electric current. The cathodic reaction is the reduction of nickel ions on the cathode and the anodic reaction is the oxidation of water on the surface of the lead anode. 

Electrowinning by Direct Reduction of Metal Oxides (FFC Process)... 

The technology of these electrowinning processes is very simple. The cells are open concrete tanks lined with rubber or plastic and the lines of anode and cathode plates are placed alternatively with a separation of 5-15 cm the cells are connected monopolar and one arrangement is shown in Fig. 4.5. The anodes are lead alloy sheets which in the sulphate medium form a lead oxide coating the metal additions to the lead (e.g. silver) are to catalyse oxygen evolution and therefore reduce the anode overpotential. The starter sheets for the cathodes are aluminium or titanium and the metal is deposited until there is a layer 3-5 cm thick, at which point the cathodes are removed from the cell. The metal is then stripped from the starter sheets and these are reused. The electrodes are typically 0.3-0.5 m in area but the anodes are always larger than the cathodes to prevent... 

Fused-salt electrolysis of K2NbFy is not an economically feasible process because of the low current efficiency (31). However, electrowinning has been used to obtain niobium from molten alkaU haUde electrolytes (32). The oxide is dissolved in molten alkaU haUde and is deposited in a molten metal cathode, either cadmium or zinc. The reaction is carried out in a ceramic or glass container using a carbon anode the niobium alloys with the cathode metal, from which it is freed by vacuum distillation, and the niobium powder is left behind. 

The sulfuric acid needed to solubilize copper from chalcocite is balanced by the acid recovered from the copper electrowinning step this acid is recycled to the heaps. The overall acid requirements for the process are, therefore, dependent on the acid consumption by the gangue minerals in the ore and the acid production by pyrite oxidation. If the pyrite associated with the ore is significant and the acid consumption by the ore is low, excess sulfuric acid can be neutralized by lime. 

Arbiter Previously known as the Sherritt-Gordon ammonia process. A process for leaching copper from sulfide concentrates, using ammoniacal ammonium sulfate solution at 85°C and relying on air oxidation. Copper is produced from the leachate by solvent extraction and electrowinning. Sulfur is recovered as ammonium sulfate. Operated on a large scale by the Anaconda Copper Company in Montana from 1974 to 1979. See Sherritt-Gordan. 

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