Amirmohammad Nasrollahzadeh - Faculty of Mining, Petroleum & Geophysics Engineering, Shahrood University of Technology, Shahrood, Iran
Mohammad Jahani Chegeni - Faculty of Mining, Petroleum & Geophysics Engineering, Shahrood University of Technology, Shahrood, Iran
Ahmad Moghooeinejad - Research and Development Center of Sarcheshmeh Copper Complex, Rafsanjan, Iran
Zahra Manafi - Research and Development Center of Sarcheshmeh Copper Complex, Rafsanjan, Iran

Due to the increasing consumption of lime in the flotation process to increase the pH of the system and create an alkaline environment, as well as its gradual increase in cost, the attention of researchers has been drawn to perform flotation operations in a neutral environment. Halophilic bacteria have the potential to replace flotation reducers such as lime because flotation can be done with their help at neutral pH as well. Also, due to the buffer effect of sea water, which is the chosen medium for bio-flotation, the use of bio-flotation method reduces the use of drinking water, and also reduces the consumption of chemicals. In this research work, five types of halophilic bacteria are studied for pyrite bio-depression and chalcopyrite flotation. Bio-flotation experiments are conducted using Hallimond tubes, and the bacteria Halobacillus sp., Alkalibacillus almallahensis, and Alkalibacillus sp. had better performance in pyrite depression and chalcopyrite flotation than other bacteria. The recovery of pyrite depression when using them was ۳۰.۹, ۳۰.۳, and ۳۴.۰ %, respectively, and the recovery of chalcopyrite flotation by them was equal to ۵۲.۹, ۶۸.۶, and ۵۵.۷, respectively, which indicates the high selectivity of these bacteria in flotation. In addition to the above tests, the effect of the combination of these three types of bacteria on pyrite depression and chalcopyrite flotation was also studied. The results obtained indicate that in the combination (mix) test of all three types of bacteria (۳۳.۳% of each type), pyrite was depressed better than other tests, and its recovery was ۲۷.۵%, which was lower than the single bacteria tests. Also, the effect of the combination of these three types of bacteria on the flotation of chalcopyrite is investigated, and its recovery was ۷۲.۶%, which was higher than the single bacteria tests. On the other hand, considering that the recovery of chalcopyrite in the three-bacteria combination tests was is higher than the single-bacteria and two-bacteria tests, it can be concluded that the combination of all three bacteria can cause a better synergism and improve their performance in micro-flotation tests.

Bioflotation, Halophilic bacteria, Combination of bacteria, Chalcopyrite flotation, Pyrite depression