A study into the use of fatty acid and xanthate collector combination in the recovery of base metal sulphides : a holistic approach

Abstract

In this study, a collector combination between xanthate and a fatty acid collector (Betacol 364) is tested on an ore containing chalcopyrite, pentlandite and pyrrhotite. An increase in the rate of pentlandite and pyrrhotite recovery was measured when the fatty acid and xanthate combination was tested against the baseline (xanthate as sole collector), using the standard laboratory scale batch flotation test procedure. The rate of mineral recovery in a batch flotation test is not only influenced by particle floatability, but also by the amount of air bubble surface area available in the pulp and the recovery of value mineral from the flotation froth. This is given as = . . where k is the rate constant (min-1), P is a parameter which represents the floatability of a mineral, Rf is the froth recovery factor and Sb bubble surface area flux. A test unit developed for this study (based on the Bikerman foam test) indicated that the fatty acid collector used (Betacol 364) has froth stabilising characteristics and thus may have increased the froth recovery ( Rf) during the batch flotation test. The increase in the rate of pyrrhotite recovery measured can therefore not only be explained by an increase in pyrrhotite floatability. In a case where the batch flotation tests are followed by plant testing and the rate of flotation increase measured during the batch test was only or partially as a result of an increase in froth recovery ( Rf), the batch test would be an unreliable test to predict plant performance. Plant operators have many variables available to manage froth recovery ( Rf), for example pulp level and frother dosing rate. For a laboratory scale batch test to be a reliable test for predicting a rate increase in plant recovery, it is necessary that an increase in the rate of recovery will be as a result of an increase in particle floatability ( P). It is recommended that a collector batch flotation test campaign must include a test to measure if the collector has frothing characteristics. The Bikerman froth stability column is demonstrated as a possible test to measure if a collector has froth stabilising characteristics. The Bikerman froth stability column test method confirmed that the fatty acid collector tested (Betacol 364) has froth stabilising properties. Additional tests are therefore recommended to confirm that the rate of recovery increase measured is as a result of an increase in pyrrhotite and pentlandite floatability (P ). Micro flotation tests performed on pyrrhotite mineral specimens confirmed that a combination between Xanthate and Betacol 364 increases the particle floatability (P ) of pyrrhotite. Laboratory scale flotation tests performed on artificial ores, consisting of a mixture of quartz and pyrrhotite mineral specimens, confirmed that the combination of Betacol 364 and xanthate increases the floatability of pyrrhotite (P ).