The synthesis of flotation collectors for cassiterite

Aryl-substituted polycarboxylic acids and aryl-substituted phosphonocarboxylic acids (including polyphosphono/polycarboxylic acids) were synthesised using new and known techniques. These acids were prepared for evaluation as potential collectors and have been assessed by Aberfoyle Resources Pty. Ltd., for use in the flotation of cassiterite and other metal oxides. The acids represent a new structural group of collectors for use in this field. The structural chemical-physical features of the acids have been correlated with the flotation results obtained to optimise collector design. Synthesis of the aryl-substituted polycarboxylic acids was carried out via established methodology to obtain thirty seven such acids, containing from one to four carboxylic acid functionalities per molecule. Various para-substituents were included to investigate the effect of both the hydrophilic and hydrophobic entities within the compounds on collector efficiency based on grade and net recovery of cassiterite. Some of these acids, notably some of the 2-(4-substitutedphenyl) propane-1,1,3-tricarboxylic acids, had not been reported previously in the literature. The aryl-substituted phosphonocarboxylic acids prepared possessed similar structural characteristics to the acids above, with one or more of the carboxylic acid groups being replaced by phosphonic acid functionalities. Previously prepared acids of this class were, in general, poorly characterised prior to this work or not found in the literature. In this work particular use has been made of N.M.R. spectroscopy ( P31, C13, H 1) to elucidate and confirm the structure of the proposed collectors. The flotation results for the two classes of collectors have been compared and contrasted, and some structure-collector property relationships proposed. In general the new classes of collectors were found to be far superior to those collectors in current commercial use.