Screening the potential of Halophilic bacteria for Pyrite bio depression

The separation of minerals has been a pressing issue in the last decades. One of the most common techniques to separate useful minerals from gangue minerals is Froth Flotation. Flotation is a relatively cheap and efficient process but the use of harmful chemicals and continuous decrease in ore quality due to the scarcity of high grade ores has motivated researchers to find alternative solutions to the standard flotation reagent scheme in order to make the process more efficient and environmentally friendly. Bioflotation has the potential of making the beneficiation of minerals more efficient and environmentally friendlier. Different bacteria and bacterial products have demonstrated to have prospective applications in bio flotation of different minerals (Behera and Mulaba-Bafubiandi, 2016). Halophilic bacteria are adapted to high salinity environments and other extreme conditions. Halophilic bacteria produce Extracellular Polymeric Substances (EPS) that aid them in the formation of biofilms and resist abrupt changes in salinity, pH, temperature and pressure. These EPS could have potential applications in flotation operations performed in sea water, such as the Copper-Molybdenum flotation operations in Chile. To date, there are no reports of halophilic bacteria been used in bio flotation experiments.
Halomonas boliviensis, Marinobacter spp, Halobacillus sp, Marinococcus sp and Halomonas eurihalina were studied to examine their potential as pyrite bio depressants, a gangue mineral common in Cu-Mo flotation. Micro flotation experiments using Hallimond tubes as well as flocculation, adsorption and Zeta potential experiments were performed in order to report the potential of these bacteria in the flotation process. In this study we will show the first results of using halophilic bacteria as Pyrite bio depressants, as well as an initial characterisation of the Extracellular Polymeric Substances excreted by these bacteria that could have an influence on the adsorption and mechanism by which these bacteria alter the surface of Pyrite.