Recovery of gold ions from ammonium thiosulfate using synergistic effect of aluminum and activated carbon

摘要

In gold hydrometallurgy, cyanide and/or halides are the wide-spread leaching reagents for the extraction of gold from primary (i.e. gold ore) or secondary resources (i.e. electronic waste). Unfortunately, since cyanide is toxic while halides are highly corrosive, considerable attention has been given to alternative leaching reagents as the noteworthy environment/human safety regulation strictly applies in conventional solutions. Among the alternatives, ammonium thiosulfate is promising reagent because of its non-toxic, low-corrosiveness as well as high-selectivity for gold (Jeon et al., 2018a). Despite those advantages, its application in commercial mining plant is still limited so far because of its serious drawback, which is that acceptable recovery technique for gold ions from pregnant solution has not yet been established. In conventional gold hydrometallurgy using cyanide or halides solution, cementation using zinc, copper or aluminium as well as adsorption using activated carbon (i.e. carbon-in-pulp/carbon-inleach) were widely employed in recovery stage (Arima et al., 2003), but application of all their techniques in ammonium thiosulfate system gives a negligible recovery efficiency (i.e. <30% of gold recovery via adsorption using activated carbon, the excessive amounts of zinc or copper in need or <10% of gold recovery via cementation using aluminum) (Jiexue and Quian, 1991, Jeon et al., 2018b).