R. Abedi Ashkavandi, E. Azimi, M.R. Hosseini, A review on bioflotation and bioflocculation of galena, Journal of Mineral Resources Engineering (JMRE) (2023).

In recent decades, application of microorganisms and their produces for bio-separation of minerals, bio-flotation and bio-flocculation, have been extensively recognized by researchers and industry. Considering several benefits of the bio-separation, in current paper, a detailed review has been conducted on bio-separation of galena from its most common accompanying minerals i.e.: sphalerite, chalcopyrite and pyrite using microorganisms and their extracellular products. Based on the findings, the bacterial cells of the Thiobacillus species have a good ability to depress and selectively flocculate galena, but the cells of the Polymyxa species have a lower ability. So, they depress and flocculate most of the sulphide minerals present in the pulp. In addition, adaptation of bacteria, especially polymixa species with galena and other minerals, will increase extracellular secretions of protein or polysaccharides. Adapted Bacillus subtilis and Bacillus megatrium can separate galena. Due to the hydrophobic nature of extracellular proteins, their less absorption on the surface of galena compared to sphalerite, causes the second mineral to be floated and galena to be depressed. On the other hand, adaptation leads to more protein secretion in the presence of galena compared to pyrite, which will cause galena to float and the second mineral to be depressed. Also, it can be said that the tendency of extracellular polysaccharides to adsorb on galena and the tendency of extracellular proteins to adsorb on sphalerite causes that, when the mixture of these two minerals comes into contact with bacterial EPS, galena is usually depressed or flocculated and sphalerite floats to some extent.