Arsenical gold ores, flotation

Flotation of arsenical gold ores associated with base metals is accomplished using a sequential flotation technique, with flotation of base metals followed by flotation of gold-containing pyrite/arsenopyrite. The pyrite/arsenopyrite is floated at a weakly acid pH with a xanthate collector. 

Arsenical gold ores that do not contain significant base metals are treated using a bulk flotation method, where all the sulphides are first recovered into a bulk concentrate. In case the gold is contained either in pyrite or arsenopyrite, separation of pyrite and arsenopyrite is practiced. There are two commercial methods available. The first method utilizes arsenopyrite depression and pyrite flotation, and consists of the following steps ... 

Gold ores can be concentrated by froth flotation, the resulting concentrate being roasted at 600-800°C to oxidize off sulphur and arsenic as their oxides. The product is extracted with cyanide under oxidizing conditions (using either peroxide or air itself) before displacement with powdered zinc. More reactive metals (silver etc.) can be removed by chlorination of molten gold. 

The refining process typically begins with crushing of the ores, then concentration by froth-flotation, which yields material that is typically 15-20% Cu. The main impurity in these concentrates is iron however, nickel, gold, and silver are often present, along with traces of zinc, selenium, arsenic, antimony, tellurium, cobalt, tin, and lead. Sihca (sand) is... 

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