Gold recovery from jewellery waste

This paper explores the potential of gold concentration from “handwashing waste” from jewellery workshops. Experiments were carried out by means of gravity separation equipment (in particular utilising the Knelson concentrator) after ascertaining that the gold occurs in the waste in the form of free particles and that the shape and size of the gold particles are suitable to separation, compared to other pollutant particles. l blending of the handwashing waste with inert particles were adopted in order to control the stability of feed to the concentrator. Equivalence relations were used to simulate the gold particles behaviour in the original waste and to find out the best operative conditions for the concentrator. Experimental results demonstrated the suitability of gravity beneficiation procedures for the preconcentration of gold particles in the sink and the elimination of much of the contaminants: it was possible to obtain a theoretical recovery up to 90% for gold particles bigger than 35 μm. Practical application on the real handwashing sample has led to a maximum recovery of up to 68%.