The effect of certain surfactants on the acid and neutral leaching of zinc calcine obtained by roasting of sphalerite concentrates

Abstract

The effect of the mixture of surfactants nonylphenolpolyethylene glycol with molecular weight 900 (D1), dinaphthylmethane-4,4′-disulphonic acid (D2) and polyethylene glycol with molecular weight 400 (D3) on the processes taking place during the acid and neutral leaching of zinc calcine was investigated: dissolution of zinc and metal impurities from calcine; precipitation of Fe(OH) 3 and AL(OH) 3 and coagulation of colloidal silicic acid solutions. The influence of the surfactant mixture (D1+D2+D3) was determined by comparing the results obtained with and without surfactants. The following effects of surfactants were found: • The presence of surfactants causes a small decrease of zinc, copper and cadmium dissolution during the acid leaching of zinc calcine; • The surfactant mixture improves deposition of impurities during the neutral leaching stage; • The volume of Fe(OH) 3 or Al(OH) 3 precipitated in solutions increases in the presence of surfactants which improves the effect of both hydroxides as scavengers; • Surfactant mixture initiates silicic acid coagulation at lower pH values compared to experiments without surfactants providing higher purification of zinc sulphate solutions and better separation from the insoluble residue.