Determination of chemicals bound to mineral surfaces in flotation processes

Combustion and extraction methods were developed for quantitative analysis of collectors adsorbed on minerals in phosphate ore processing. The combust ion analysis is based on the oxidation of carbon in a high-purity oxygen st ream followed by an IR detection of the evolved carbon dioxide. A commercia l combustion analyser, LECO RC-412, was modified to meet the high demands o f sensitivity and selectivity for analysing small amounts of collectors in the presence of carbon bearing minerals. In the extraction method, the chem icals adsorbed on mineral surfaces were extracted into chloroform, potassiu m bromide was added and the chloroform evaporated. Finally, the dry potassi um bromide containing the organic chemicals was pressed in a standard manne r to produce a KBr disc for IR analysis. As little as ca. 20 g collector pe r one ton of ore could be determined, thus demonstrating the suitability of the developed methods for flotation practise. By combining the results of the collector analysis and mineralogical analysis with the process data, th e distribution of flotation chemicals on individual minerals can be calcula ted by solving a set of linear equations. This is demonstrated in a case wh ere apatite is floated from low-grade calcareous phosphate ore. (C) 2000 Pu blished by Elsevier Science Ltd. All rights reserved.