Investigation of the interactive effects of the reagent suite in froth flotation of a Merensky ore

Abstract

Interpretation of the behaviour of reagents in flotation is made complex by the existence of secondary effects, which can override the desired effects that enable effective separation, in addition to a predominant role of a flotation reagent, and the incomplete liberation of the mineral particles. Moreover, accumulation of dissolved ions due to the water recycle and reuse practice in processing circuits, which alters the chemical environment in the pulp and impacts the overall performance of the process, adds to this complexity. Therefore, it is often challenging to precisely assess individual contributions of the reagents to the overall performance, and hence the need for a holistic approach in evaluating the behaviour of reagents in flotation. Factorial design of experiments offers such an approach. This study used a factorial design approach in an effort to determine the interactive effects between chosen flotation reagents; collector, depressant, frother and water quality on the metallurgical performance of a Merensky ore. Increasing the ionic strength of the plant water increased recoveries, and the effect on decreasing concentrate grade was minimal, therefore the practice of water recycle and reuse should not impose any adverse impact during beneficiation of the PGM-bearing ore from the Merensky reef. It was also observed that higher recoveries were obtained with high ionic strength plant water than high frother dosage, indicating that the use of saline water in froth flotation of certain ores can replace the use of frothers, thus reducing costs. The factorial design approach can be useful in evaluating the simultaneous effects of such variables in the flotation process, thereby giving better understanding of their overall effect on the whole process.