Processing of gold-antimony concentrates

Abstract

This paper describes the results of a study that looked at processing of goldantimony concentrates with selective extraction of antimony and gold as commodities. The common global practice of processing antimony sulphide concentrates (20–30% Sb) is based on alkaline sulphide leaching followed by precipitation of metallic antimony by electrowinning. However, application of this technique to process sulphide concentrates that, apart from antimony, also contain gold, can be difficult as, together with antimony, up to 10–15% of gold can leach to the solution. It takes a special process during final refining of cathode antimony to recover that gold. This paper describes a process that involves two stages of atmospheric leaching of antimony. The gold that leached to the solution is precipitated with zinc after the first stage of antimony leaching. Together with atmospheric leach tailings, it then goes to the pressure oxidation unit. This process helps oxidize the rest of the sulphides and release refractory gold. The resultant cake is processed following a standard sorption cyanidation technique. The paper looks at the antimony leaching rate and the rate at which gold leaches to the solution during this process. The paper describes the results of selective precipitation of gold from gold-antimony solutions and highlights certain features of this process. A series of tests was conducted to test the techniques of pressure oxidation of atmospheric leach tailings and cyanidation of the residue. The paper also describes a process that was developed for processing of goldantimony concentrates and precipitation of antimony and gold. An antimony recovery exceeding 90–95% can be achieved when using this process. At the same time, the percent of dissolved gold can be reduced from 10–15 tо 1–3%.