GB1478502A - Electrowinning metal from chloride solution - Google Patents

Abstract

1478502 Electrowinning metals FALCONBRIDGE NICKEL MINES Ltd 17 Nov 1975 [25 Nov 1974] 50892/74 Heading C7B In a method for electrowinning metal from a chloride electrolyte in an open cell, the electrolyte fed to the cell is partly withdrawn at an overflow to maintain a constant level, and each anode 11 together with a body of surrounding electrolyte 24 is maintained within an electrolyte-permeable diaphragm 21 attached to a closed hood 22 extending above the electrolyte level 27. Suction is applied to the hood to withdraw gaseous chlorine and a second portion of electrolyte which is drawn through the diaphragm and up into the hood above level 27, whereby diffusion of chlorine through the diaphragm into and evolution of gaseous chlorine from the exposed electrolyte are reduced. A chlorine concentration above the exposed electrolyte of below 1ppm is recommended. Suction may be applied from a common manifold 26 which serves each anode with chlorine and anolyte being removed through a single pipe 25. Alternatively a separate chlorine removal pipe 30 is provided. The anolyte may be dechlorinated and recycled. The cell level 27 may be maintained by an adjustable wier. Usual electrode and diaphragm materials are referred to, for electrowinning Ni or Co. For these metals an anolyte pH respectively below 2À0 and below 1À7 is necessary, and undesired pH rises may be counteracted by feeding fresh electrolyte to and withdrawing the catholyte overflow from the top of the cell.