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Electrowinning and Refining

The electrowinning of metals, or the production of metals from their ores once put in solution or liquefied, is the oldest industrial electrolytic process. Sodium metal was first prepared in 1807 by the English chemist Humphrey Davy, who obtained it using electrolysis of molten sodium hydroxide. Several industrially important metals (the active metals which react with water) are produced commercially today by electrolysis of molten salts.

Metal deposition rates are key parameters in developing an effective electrowinning unit. Units are most effective when installed in rinse tanks immediately following drag-out tanks. Electrowinning is not a viable recovery technology for all metals. While the process works well for metals with high electro-potential, such as gold, silver, copper, cadmium and zinc, it does not work as well on others, such as chromium. Nickel can be recaptured also. However, the process is very pH sensitive and must be rigorously maintained for any deposition to occur. For metals which electrowinning works, the following criteria are important in the operating performance of electrowinning units:

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