Mathematical model of gold lixiviation [articol]

Abstract

Processing of different refractory gold ores by wet chlorination, followed by chloroauric complex (HAuCl₄) separation by adsorbtion on macroporous polymers (ion exchange resin) was studied and patented by INCDMRR – ICPMRR [1,2]. This work presents the theory and practice aspects of gold lixiviation by wet chlorination. The present work theoretically aproaches the gold lixiviation from refractory gold ores. Thus, the gold lixiviation using nascent chlorine at the ambient temperature from hidrogravitationally refractory concentrate, was experimented. The gold lixiviation mechanism presume the initial AuCl formation on the metallic gold surface followed by complexing with Cl⁻ to AuCl₂⁻. This complex is oxidized in solution with NaOCl to AuCl₄⁻ [3,4]. The succes of gold lixiviation from hydroclorous solutions using Cl⁻/NaOCl solutions depends on mineralogical composition of material. A mathematical model for lixiviation time computing was proposed, using as parameters the initial radius of gold particle ( Rin ) and molar fraction of chlorine in solution ( yCl₂∞).