Statistical model of gold recovery from chloride media using Amberlite XAD-7 [articol]

Abstract

The paper presents a study on the statistical modeling of the results obtained in the selective recovery of gold from hydrochloric solutions using Amberlite XAD-7 ion-exchange resin. Experimental tests were conducted on real solutions obtained following selective leaching of gold from different metallurgical wastes, through wet chlorination. The influence of several variables such as: acidity of the working solution, the flow through the bed , temperature, eluent acidity, the flow rate and the acetone/hydrochloric acid ratio has been studied. As a result of the experimental tests performed, it was established that the optimum conditions for the adsorption step were: solution acidity 2.5M HCl, solution flow rate through the bed 1.11 · 10-9 m3/s (3Bev/h) and a room temperature. The loaded resin was eluted with an mixture of organic solvent (acetone) and hydrochloric acid. The process efficiency of the gold elution from the Amberlite XAD-7 resin is higher as the fictive flow rate of the eluent is lower and increases with the increase of the eluent acidity and with the increase of the acetone quantity in the eluent (with the increase of the volumetric ratio between acetone and hydrochloric acid). The gold recovery efficiency based on the Amberlite XAD-7 selective ion-exchange resin was over 99.8%.