EFFECT OF PH AND CHAIN LENGTH ON THE FLOTATION SEPARATION OF FLUORITE FROM ITS SYNTHETIC MIXTURES WITH CALCITE AND DOLOMITE WITH IMINO-BIS-METHYLENE PHOSPHONIC ACID

摘要

Alkyl Imino-bis-methylene phosphonic acids (IMPA) have been found to be highly selective flotationcollectors for fluorite for its separation from other calcium minerals. As little as 10-7 mole per literof IMPA is enough to achieve complete flotation of fluorite during the micro-flotation experiments.Other calcium minerals require orders of magnitude higher concentration of IMPA for flotation.The observed selectivity of fluorite with IMPA as compared to other calcium minerals as well ascompared to other flotation reagents has been predicted by molecular modelling computations forthis mineral-reagent separation system.The flotation response of fluorite, calcite and dolomite minerals procured from two differentsources with IMPA of two different chain lengths (consisting of 8 and 12 carbon atoms, respectively)and at different solution pHs’ have been investigated in this work. The flotation results on mineralsfrom two different sources have been found to be remarkably close suggesting that the origin(source) of mineral is not critical in this case. The alkyl chain length of the collector is observed tohave a significant effect on the pH at which selective flotation is possible. The flotation results onthe separation of fluorite from its synthetic binary mixtures with calcite and dolomite using IMPAreagents confirm the trends observed during single mineral flotation tests. Interestingly, while thepH range (5 to 10) of maximum flotation for fluorite remains the same irrespective of chain length,the pH of maximum calcite flotation shifts to alkaline pH’s with increasing chain length of IMPA(pH 6 for IMPA 8 to pH 10 for IMPA 12). These interesting observations are demonstrated to berelated to the complex solution chemistry and the effect of soluble calcium ions on the flotation ofrelatively more soluble minerals like calcite, in alkaline pH range.