Amphiphilic cellulose and surfactant mixtures as green frothers in mineral flotation. 2. Flotation of chalcopyrite and Cu-containing tailings

Abstract

Froth flotation represents one the most important technologies for the development of the modern era, as it has enabled a steady and affordable flow of mineral raw materials. Recent studies show an increasing demand for more environmentally friendly processes, resulting in stricter regulations and the need to gain social license to operate by mining operations. As the demand of raw materials keeps growing, and ore grades decline, there is an urgent need to improve the efficiency of flotation as well as reducing the environmental impact of enrichment processes.The work hereby presented explores a novel type of frother chemistry, where commercial frothers are partially substituted with a biodegradable molecule produced from sustainable sources (namely, hydroxypropyl methyl cellulose) to form polymer-surfactant (PS) mixtures. In the second part of this series, the unique froth stabilization of this PS-mixture is tested in a bench-scale flotation study on chalcopyrite model ore. The use of PS-mixtures results in a robust system capable of maintaining separation efficiencies (SE) at ca. 90 % even under conditions of low pH (i.e., 5.5) and low collector concentration (i.e., 5 g/ton). In comparison, benchmark commercial frothers had a significant decrease in SE under these conditions (ca. 78 %). The advantageous performance of the PS-mixture frother is further tested in a short case study made with Cu-bearing sulfidic tailings. The outcome of this study demonstrates for the first time various advantages of the PS-mixtures in froth flotation, including: i) the generation of a stable, yet selective froth phase with sustainable reagents; ii) a robust flotation performance, able to withstand changes in pH and collector concentration, and iii) the ability to selectively float minerals with low hydrophobicity, such as those found in tailings deposits.