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Specialty collectors are strong, selective flotation promoters developed to improve metallurgy on difficult ores. They are used primarily in the flotation of copper and copper-activated zinc, but could find utility in nickel flotation as well. Their main advantage is selectivity over pyrite and pryrrhotite in alkaline media. Other advantages include performance equal or superior to that of xanthates at lower alkaline media. Other advantages include performance equal or superior to that of xanthates at lower alkalinities, thus saving costs in lime. In the flotation of zinc, these collectors will normally reduce the amount of copper sulfate needed for activation, with a potential for substantial savings.
The currently used specialty collectors are generally water-insoluble liquids such as the DOWFROTH* frothers, alcohols, etc. that are soluble in most organics. The are stable in both acid and alkaline pulps and do not age with time. This latter characteristic is extremely important to mills in isolated locations. The products have relatively low flash points, so proper ventilation and protection against fire hazards are required.
The first collector of this type was introduced to the mining industry by The Dow Chemical Company. This product, chemically isopropyl ethylthionocarbamate, has the structure shown below.
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