Flotation of gold ores

Mining. Numerous patents have advocated the use of alkanolamines in mining appHcations. Triethanolarnine has been used as a depressent in the flotation of copper (164), in the electrotwinning of gold (165), and as an aid in the froth flotation of nickel ores. Phosphate ore flotation has been improved through the use of a fatty acid condensate with ethanolamine (166). Beneficiation of tin ore has been accompHshed using fatty acid alkanolamides (167). 

Rather than reiterating what is well known about flotation of gold, PGMs and oxide minerals, emphasis has been placed on the separation methods which are not so effective when using conventional treatment processes. These difficult separation methods are largely attributed to problems with selectivity between valuable minerals and gangue minerals, especially in the flotation of oxide ores and base metal oxides, such as copper, lead and zinc oxide ores. 

Literature on flotation of gold, PGMs, rare earths and various oxides is rather limited, compared to literature on treatment of sulphide-bearing ores. As mentioned earlier, the main problem arises from the presence of gangue minerals in the ore, which have flotation properties similar to those of valuable minerals. These minerals have a greater floatability than that of pyrochlore or columbite. In the beneficiation of oxide minerals, finding a selectivity solution is a major task. 

In spite of the lack of basic research on flotation of gold-bearing ores, the flotation technique is used not only for upgrading of low-grade gold ore for further treatment, but... 

The flotation of gold-bearing ores is classified according to ore type (i.e. gold ore, gold copper ore, gold antimony ores, etc.), because the flotation methods used for the recovery of gold from different ores is vastly different. 

In flotation of gold-containing base metal ores, a number of modifiers normally used for selective flotation of copper lead, lead zinc and copper lead zinc have a negative effect on the floatability of gold. Such modifiers include ZnS04-7H20, S02, Na2S205 and cyanide when added in excessive amounts. 

FLOTATION OF GOLD-CONTAINING MERCURY/ANTIMONY ORES... 

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. 

Flotation of Gold From Base Metal Sulphide Ores... 

FLOTATION OF GOLD FROM BASE METAL SULPHIDE ORES... 

Flotation of gold-bearing sulphides from ores containing base metal sulphides present many challenges and should be viewed as flotation of the particular mineral that contains gold (i.e. pyrite, arsenopyrite, copper, etc.), because gold is usually associated with these minerals at micron size. 

Benzotriazoles can be used to flotate copper ore and copper slag. Meantime, they can be used with xanthate or aerofloat in the flotation of gold and silver ores. 

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. 

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