MIST SUPPRESSANT FOR SOLVENT EXTRACTION METAL ELECTROWINNING

摘要

The invention relates to a process for the recovery of elemental metal values from ores and processing liquids by solvent extraction-eletrowinning. The process involves extracting metal values by means of an aqueous strip solution containing strong acid such as sulphuric or phosphoric acid. The aqueous strip solution containing the metal values is used as electrolyte in an electro-plating process to electrowin the metal values. A problem which has arisen is that oxygen evolved at the anode during electroplating entrains the strong acid electrolyte, to form a fine mist or spray which is corrosive and constitutes a health hazard. In the present invention, the aqueous strip solution contains from 1 to 200 parts by weight of fluoroaliphatic surfactant, per million parts of strip solution, the surfactant having at least one cationogenic group which is the radical of a base having an ionization constant in water at 25.degree.C of at least 10-6, and containing at least 30 weight percent fluorine in the form of carbon-bonded fluorine in a fluoroaliphatic radical, said fluoroaliphatic radical having at least 4 carbon atoms and at least a terminal perfluoromethyl group. The invention inhibits or suppresses acidic mist formation above electrowinning tanks.