Separation and recovery of germanium from a zinc plant (ÇİNKUR A.Ş.) precipitate by emulsion liquid membranes

Key words: Germanium, emulsion liquid membranes, solvent extraction, acidic leach liquors, Kelex 100 The ?copper? cake, obtained from a zinc plant (Çinkur Co., Kayseri) electrolite purification section, consists an average of 1450 ppm germanium, 16 % copper, 19,8 % zinc, 2,6 % cadmium, 0,38 % aluminium,0,72 % cobalt, 0,52 % nickel, and 0,26 % iron. This precipitate has been leached with a 150 g/L H2SO4, solid/liquid ratio ¼, and thus acidic leach liquor are obtained. Copper in the solution has been precipitated in an elemental form by cementation adding iron dust. Liquid membrane process has recently received an increasing attention as an alternative and similar process to solvent extraction in waste water treatment, hydrometallurgy, biochemical and nuclear waste processing. The extraction of germanium from acidic leach liquors and its separation from other ions have been experimentally studied by an emulsion type liquid membrane. The important parameters, affecting on the germanium extraction, such as solvent type, surfactant (ECA 4360J) concentration, extractant (Kelex 100) concentration, stirring speed, stripping solution (NaOH) concentration, modifier type and concentration, treatment ratio (VE/VF), and phase ratio (Vs/Vm) have been examined and the optimum conditions have been obtained. In the optimum conditions, for the acidic leach solution, pH being 0.80, that contains 284,6 mg/L Ge, 42,60 g/L Zn, 8,87 g/L Cd, 40,08 g/L Fe, 2,00 g/L Co, 1,00 g/L Al, 99.1 % of germanium has been extracted, and the separation factors of germanium with respect to Zn, Cd, Fe, Co, Ni and Al, based on the initial feed concentration, have been found to be of 11,8, 6,1, 1223, 16,8, 7,3, and 14,4, respectively, in 20 minutes.