Arsenic in Gold Processing

Abstract

Abstract The processing of gold bearing sulphide minerals which contain arsenopyrite and other complex arsenic sulphide minerals results in arsenic containing emissions and effluents which must be given careful consideration in relation to clean air and clean water standards. The sources of arsenic and the various process options for treating arsenical gold ores and concentrates are briefly reviewed The problem relating to the removal of arsenic from gaseous emissions from roasting processes is considered Residues from aqueous processing contain a variety of arsenical materials which have not been characterised, and the long-term stability of these is suspect The use of lime to stabilise aqueous residues as cither calcium arsenate or calcium arsenite has been shown to be inadequate for long term disposal since both compounds are converted into calcium carbonate due to the influence of carbon dioxide in the atmosphere Ferric ion solutions have been used to precipitate ferric arsenate or to form ferric hydroxide which binds the arsenic for short term disposal. The long term stability of these ferric materials is poor, but could lead to the acceptance of a slow release option rather than complete containment of residues.