Bioleaching for Efficient Copper Ore Recovery

Authors: Zh. Karaulova, D. Baizhigitov

Abstract:

At the Aktogay deposit, the oxidized ore section has been developed since 2015; by now, the reserves of easily enriched ore are decreasing, and a large number of copper-poor, difficult-to-enrich ores has been accumulated in the dumps of the KAZ Minerals Aktogay deposit, which is unprofitable to mine using the traditional mining methods. Hence, another technology needs to be implemented, which will significantly expand the raw material base of copper production in Kazakhstan and ensure the efficient use of natural resources. Heap and dump bacterial recovery are the most acceptable technologies for processing low-grade secondary copper sulfide ores. Test objects were the copper ores of Aktogay deposit and chemolithotrophic bacteria Leptospirillum ferrooxidans (L.f.), Acidithiobacillus caldus (A.c.), Sulfobacillus acidophilus (S.a.), represent mixed cultures utilized in bacterial oxidation systems. They can stay active in the 20-40 °C temperature range. Biocatalytic acceleration was achieved as a result of bacteria oxidizing iron sulfides to form iron sulfate, which subsequently underwent chemical oxidation to become sulfate oxide. The following results have been achieved at the initial stage: the goal was to grow and maintain the life activity of bacterial cultures under laboratory conditions. These bacteria grew the best within the pH 1,2-1,8 range with light stirring and in an aerated environment. The optimal growth temperature was 30-33 оC. The growth rate decreased by one-half for each 4-5 °C fall in temperature from 30 °C. At best, the number of bacteria doubled every 24 hours. Typically, the maximum concentration of cells that can be grown in ferrous solution is about 107/ml. A further step researched in this case was the adaptation of microorganisms to the environment of certain metals. This was followed by mass production of inoculum and maintenance for their further cultivation on a factory scale. This was done by adding sulfide concentrate, allowing the bacteria to convert the ferrous sulfate as indicated by the Eh (> 600 mV), then diluting to double the volume and adding concentrate to achieve the same metal level. This process was repeated until the desired metal level and volumes were achieved. The final stage of bacterial recovery was the transportation and irrigation of secondary sulfide copper ores of the oxidized ore section. In conclusion, the project was implemented at the Aktogay mine since the bioleaching process was prolonged. Besides, the method of bacterial recovery might compete well with existing non-biological methods of extraction of metals from ores.

Keywords: Bacterial recovery, copper ore, bioleaching, bacterial inoculum.

References:

[1] A.S. Chernyak, A.Y. Safronova, A.V. Kashevskyi Biotechnology and Bioinorganic chemistry of noble metals: status and prospects, Mater. Scientific and practical conference “Chemistry and Chemical Technology at the Turn of the Millennium” (Tomsk, March 2000): Tomsk: TPU Publishing House, 2000. – Т. 1. – pp. 169-172.
[2] G.I. Karavaiko Role of microorganisms in metal leaching, G.I. Karavaiko, S.I. Kuznetsov, A.I. Golomzik. Moscow: Nauka, 1972, pp. 272.
[3] S.I. Polkin, E.V. Adamov, V.V. Panin “Biogeotechnology metals”. Moscow: Nedra, 1985, pp. 243.
[4] G.A. Sokolova, G.I. Karavaiko, Physiology and geochemical activity of thionic bacteria, M., 1964.
[5] T.F. Kondratyev, T.A. Pivovarova, L.N. Krylova, V.S. Melamudov, E.V. Adamov, G.I. Karavaiko, “Leaching of Copper Ore from the Udokanskoe deposit at low temperatures by an association of acidophilic chemolithotrophic microorganisms,” Applied Biochemistry and Microbiology, 2011, Vol. 47, No. 5, pp. 572-578
[6] Watling, H.R. The bioleaching of sulphide minerals with emphasis on copper sulphides. A review. Hydrometallurgy. 2006. 84. 81–108.https://doi.org/10.1016/j.hydromet.2006.05.001.
[7] Foucher S. Evolution of the bacterial population during the batch bioleaching of a cobaltiferous pyrite in a suspended-solids bubble column and comparison with a mechanically agitated reactor / S. Foucher, F. Battaglia-Brunet, P. d’Hugues et.al. // Hydrometallurgy, 2003. № 71. Pp. 5-12.
[8] Kondratyeva T.F., Pivovarova T.A., Karavaiko G.I. Structural features of chromosomal DNA in strains of Thiobacillus ferrooxidans adapted to growth on media with pyrite or elemental sulfur. // Microbiology. Microbiology. – 1996. – Т65, № 5. – pp.675 – 681.
[9] Krylova H.H., Adamov E.V., Pivovarova T.A., Kondratieva T.F. Regimes of heap bacterial-chemical leaching of copper ore from the Udokan deposit // Nonferrous Metals. Udokan deposit // Non-Ferrous Metals. – 2011. - № 7. – pp. 16 – 20.
[10] Craven P. Alliance Copper: the Billiton-CODELCO strategy for commercializing copper bioleaching / P. Craven, P. Morales// Randol Copper Hydromet Roundtable, 2000. Pp. 119-126.
[11] Biotehnology of metal. Practical guidance / G.I. Karavaiko, DJ. Rossi, A. Agate, S. Grudev and Z.A. Avakyan. TSMP GKNT. Moscow, 1989. P.375.
[12] Kochurov, B.I. Economics and management of nature use: textbook / B.I. Kochurov, V.L. Yulinov; Northern Arctic) Federal University named after M.V. Lomonosov. – Arkhangelsk: Northern (Arctic) Federal University (SAFU), 2013. Рр.- 215.
[13] A.A. Tajitdin O.O. Bacterial leaching of copper-containing tailings (Almaty): master’s thesis. master.tehn. sciences Tajitdin, 2020. рp. – 46-48.