Novel approach for selective recovery of gold, copper, and iron as marketable product from industrial effluent

Abstract

Globally, continuous R & D efforts are being made to recuperate precious metals from wastes in order to conserve the natural resources as well as minimize environmental pollution. Keeping in view of the above, a process has been developed to recover gold from industrial effluent using hydrometallurgical route. Initially, the effluent was pre-treated using precipitation and solvent extraction techniques to remove impurities, i.e., iron and copper as value added products. Iron was removed up to 99.99% at pH 3.5. Further, copper was extracted using 10% LIX 84IC maintaining phase ratio 1/1 in mixing time of 15 min and equilibrium (eq.). pH 2.2. Selective adsorption of gold was carried out using ionenaustauscher-II and resulted in 99% gold adsorption between pH 7 and 8 in contact time of 30 min. Experimental results obtained for the adsorption of gold was found to follow second order reaction and fitted well with the Freundlich isotherm. Gold from the loaded resin was eluted using a mixture of hydrochloric acid and thiourea. From the pure gold solution, metal could be produced using cementation/charcoal adsorption followed by heat treatment, respectively.