Vegetable lipid oil-based collectors in the flotation of apatite ores

Abstract

Apatite ores of igneous carbonatite origin are the most important phosphorus source in Brazil. Most of these ores are deeply or partially weathered, having complex chemical and mineralogical compositions. Rice bran oil and soybean oil were the vegetable lipid oils evaluated as raw materials for saponified fatty acids collectors, in the flotation of apatite ores; linseed oil was included, for comparison reasons. They were characterized by chemical wet methods and gas chromatography. Flotation was studied by two approaches: a) microflotation tests using pure apatite and reagent grade fatty acids; b) bench scale flotation tests, using a typical weathered apatite ore; the collectors were the vegetable oils, after saponification; the tests ran under realistic conditions, at pH = 10. The microflotation tests showed that, at basic pH, linoleic acid was the best collector for apatite, followed by linolenic and oleic acids. These results were fully confirmed by the bench scale flotation tests with the apatite ore; the best natural oils, as collectors for apatite ores, were those richer in linoleic acid. Soybean oil was the best collector, considering P₂O₅ grade and recovery, and Fe₂O₃ content (as a measure of gangue minerals contamination). However, linseed oil yielded excellent results, too. Although being a practical collector for apatite flotation, rice bran oil always gave the worst results, among the three vegetable lipid oil-based collectors tested.