STUDY ON THE USE OF ACIDOPHILIC IRON OXIDIZING BACTERIA FOR DISSOLVING IRON FROM LOW-GRADED CHALCOPYRITE ORES

Nguyen Van Hung

Abstract


Biomining is a microbiological-based approach to extract minerals from ores without adding acids and other extraction chemicals. Having biological nature, the process is considered environmental friendly and tends to be applied more widely nowadays, especially for low-graded ores, for which chemical extraction is no longer efficient. 

In this study, two iron oxidizing bacterial strains Acidithiobacillus sp. IOB1 and Leptospirillum sp. IOB2 originated from mining sites in Vietnam were used in laboratory leaching experiments for the recovering minerals from low-graded chalcopyrite ores. The obtained results showed that both strains could significantly accelerate the leaching process, the highest iron dissolution rate was estimated for 0.83 g×kg-1×d-1 within two weeks of incubation with strain IOB2, about 30 % and 50 % respectively higher than leaching with strain IOB1 or control without bacteria, respectively. The iron extraction from ores was also evidenced by EDX analyses comparing the ore particles before and after incubation with the bacteria. Microscopic observation of DAPI-stained ore particles also showed high cell density attached to the particles, instead of freely moving in the liquid extract. Furthermore, FISH analyses using a specific probe for the g-Proteobacteria GAM42a revealed that only ~50 % of DAPI-stained cells were Acidithiobacillus sp. IOB1 – like in the leaching experiment with this train as starting culture, indicating that other bacterial species have developed and contributed to the metal dissolution here; however very rare positive signals were observed in leaching experiment with strain IOB2 as starting culture or the control without added bacteria. Thus, the acidophilic iron oxidizing strains Acidithiobacillus sp. IOB1 and Leptospirillum sp. IOB2 could serve as potential microbial sources for the development of biologically based approaches to extract minerals from ores, especially for those having low mineral contents.



Keywords


Acidophilic iron oxidizing bacteria, bioleaching, low-graded chalcopyrite ores, Acidithiobacillus sp., Leptospirillum sp.

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DOI: https://doi.org/10.15625/2525-2518/54/4A/11990 Display counter: Abstract : 48 views. PDF : 40 views.

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Published by Vietnam Academy of Science and Technology