Amirmohammad Nasrollahzadeh; Mohammad Jahani Chegeni; Ahmad Moghooeinejad; Zahra Manafi
Abstract
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 ...
Read More
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 30.9, 30.3, and 34.0 %, respectively, and the recovery of chalcopyrite flotation by them was equal to 52.9, 68.6, and 55.7, 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 (33.3% of each type), pyrite was depressed better than other tests, and its recovery was 27.5%, 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 72.6%, 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.
Z. Manafi; M. Kargar; F. Kafilzadeh
Abstract
Optimization of the effective parameters in the copper bioleaching of chalcopyrite concentrates (CuFeS2) is studied by moderately thermoacidophilic microorganisms. The microorganisms with extensive metabolic properties are used in two different ways: 'top-down' and 'bottom-up'. The bioleaching experiments ...
Read More
Optimization of the effective parameters in the copper bioleaching of chalcopyrite concentrates (CuFeS2) is studied by moderately thermoacidophilic microorganisms. The microorganisms with extensive metabolic properties are used in two different ways: 'top-down' and 'bottom-up'. The bioleaching experiments are performed based on the parameters of silver, activated charcoal, concentrate type (Sarcheshmeh and Miduk), and a type of bacteria. By regrinding the concentrate particles down to 10 µm, bottom-up consortium, 500 ppm silver, and 3 g/L of coal, more than 97% of the copper from the Miduk chalcopyrite concentrate is recovered within 12 days. The final recovery of the control test without the microbes is 35%. The performance of the bottom-up method is significantly better than the top-down one. The moderate thermophiles have an important role in copper biomining.
