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All flotation concentration processes are selective (or differential) in that one mineral or group of minerals is floated away from the accompanying gangue. The separation of unlike minerals – such as sulfides from nonsulfides – is commonly referred to as “bulk flotation”. The term “differential flotation” is restricted to operations involving separations of similar mineral types. “Differental flotation” is the concentration of and subsequent successive removal of copper, lead, zinc and iron sulfides from a silgle ore.
By proper application of modifying agents, differential separation often can be made using the same collector agent for all the concentrations. With other ores, a different collector may be required in each flotation stage. The variations in flotation activity between different ores containing the same minerals may be due to differences in geological history, degree of oxidation, presence of interfering soluble salts, or yet other causes. Because its is seldom possible to control or even to determine all of the variables in a flotation circuit, each ore must be considered as a separate problem. Even then, the character of an ore may change from hour to hour in mill operation, thus creating constant new challenges to the flotation metallurgist.
Predicting correctly the precise flotation activity of an ore on the basis of examination and analysis is difficult at best. A number of correlations have been noted, and they from the basis for certain general rules or procedures. However, the lack of hard-and-fast absolute rules, rules, and the imperative need for practical in-process evaluations should be kept in mind while reading this bulletin. |
