The surfaces of native or free gold containing particles are normally hydrophobic and, if the surfaces of such particles are relatively free of contaminants they will have a tendency to float without the addition of a collector. The major sources of contamination on free gold particles are processing chemicals and small particle slime coatings. Gold tellurides also have a strong natural flotation tendency and will, for the purpose of this article, be put into this natural flotation discussion.
The trends in the area of free gold that will be addressed in this section include: 1) the impact of gold particle size on recovery and rate of flotation: 2) the need to choose collector type, carefully, to minimize collector dosage, and to be at or near natural ore pH conditions; 3) the importance of a balanced frother selection; 4) some special operating factors; and 5) the processing of carbonaceous gold ores.
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