Characterisation of Biooxidation Feed and Products for Improved Understanding of Biooxidation and Gold Extraction Performance
International Journal of Mineral Processing and Extractive Metallurgy
Volume 5, Issue 2, June 2020, Pages: 20-29
Received: Mar. 13, 2020;
Accepted: Apr. 2, 2020;
Published: May 15, 2020
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Grace Ofori-Sarpong, Department of Minerals Engineering, University of Mines and Technology, Tarkwa, Ghana
Ahmed-Salim Adam, Department of Minerals Engineering, University of Mines and Technology, Tarkwa, Ghana; Golden Star Prestea/Bogoso Resources, Bogoso Mine, Ghana
Richard Komla Asamoah, Future Industries Institute, University of South Australia, Mawson Lakes, Australia
Richard Kwasi Amankwah, Department of Minerals Engineering, University of Mines and Technology, Tarkwa, Ghana
This paper presents a study on characterisation of refractory ore, biooxidation feed and product, and cyanidation tailings with the aim of understanding the causes of excessive continuous frothing, incomplete sulphide oxidation, high reagent consumption, high cyanidation residues and low overall recovery as encountered in biooxidation of refractory ores. Techniques involving carbon and sulphur speciation, Quantitative X-Ray Diffraction (QXRD), Scanning Electron Microscopy (SEM) and Optical Microscopy (OM) were used to characterise the ore samples, flotation concentrate (BIOX® feed), biooxidised product (BIOX® CIL Feed) and cyanidation tailings (BIOX® CIL Tails) from a biooxidation plant. The main minerals present in the ore were quartz (45%), chlorites (21%), plagioclase feldspar (13%), dolomite (5%), pyrite (2%) and mica group (2%). The flotation concentrate recorded 18% mica, and this was responsible for excessive frothing in the biooxidation circuit as confirmed by the QXRD analysis. The carry-over froth to the CIL circuit led to short-circuiting of poorly leached material into the cyanidation tailings, resulting in high cyanidation residues. Secondary refractory minerals; gypsum and jarosite, which were observed in the biooxidation product by the QXRD, have the potential to coat unreacted sulphide particles, leading to incomplete sulphide oxidation as observed here. Partially oxidised sulphides led to high consumption of reagents such as oxygen and cyanide during cyanidation. Gypsum and jarosite also encapsulated gold particles as observed in the BSED analysis. Coated gold particles had reduced access to lixiviants during the subsequent cyanidation process, leading to high leach residues. The biooxidised product (BIOX® CIL Feed) also recorded a high organic carbon content of 6.67, while analysis by BSED revealed the presence of graphitic carbon and coatings on gold surfaces; an indicator for high preg-robbing activities during cyanidation of the concentrate. Preg-robbing indices of 64.4% and 72.7% were recorded for the flotation concentrate (BIOX® feed) and BIOX® CIL feed respectively. The overarching effect of all the observations is a decrease in overall gold recovery.
Richard Komla Asamoah,
Richard Kwasi Amankwah,
Characterisation of Biooxidation Feed and Products for Improved Understanding of Biooxidation and Gold Extraction Performance, International Journal of Mineral Processing and Extractive Metallurgy.
Vol. 5, No. 2,
2020, pp. 20-29.
P. Miller, and A. R. G. Brown, Bacterial oxidation of refractory gold concentrates, [in] Gold ore processing - project development and operations, Elsevier, Amsterdam, Netherlands, 2016, p. 359.
J. C. Yannopoulos, The Extractive Metallurgy of Gold, Von Nostrand Reinhold, New York, 1991.
M. Aylmore and A. Jaffer, Evaluating process options for treating some refractory ores, Proceedings of Alta Gold Conference 2012, Perth, Australia, 2012.
C. L. Brierley, Mining biotechnology: research to commercial development and beyond”, In: Rawlings, D. E. (Ed.), Biomining: theory. microbes and industrial processes, Springer Verlag, Berlin, Germany, 1997, p. 3.
J. Marsden, and I. House, The Chemistry of gold extraction, 2nd edition, Ellis Horword, New York, 2006.
G. J. Olson, J. A. Brierley and C. L. Brierley, Bioleaching review part B: progress in bioleaching: applications of microbial processes by the minerals industries, Appl. Microb. Biotechnol., 97 (2013) No. 17, p. 7543.
H. R. Watling, Review of biohydrometallurgical metals extraction from polymetallic mineral resources. Miner., 5 (2015), p. 1.
S. Hedrich, A. G. Guézennec, M. Charron, A. Schippers, and C. Joulian, Quantitative monitoring of microbial species during bioleaching of a copper concentrate, Frontiers in Microbiol., 7 (2016), p. 2044.
D. E. Rawlings, Microbially-assisted dissolution of minerals and its use in the mining industry, Pure Appl. Chem., 76 (2004), No. 4, p. 847
R. K. Amankwah, W. T. Yen, and J. Ramsay, A two-stage bacterial pretreatment process for double refractory gold ores, Miner. Eng., 18 (2005), p. 103.
J. A. Brierley, and C. F. Kulpa, Biometallurgical treatment of precious metal ores having refractory carbon content, US Patent, 5 (1993), p. 244.
G. Ofori-Sarpong, and K. Osseo-Asare, Preg-robbing of gold from cyanide and non-cyanide complexes: effect of fungi pretreatment of carbonaceous matter”, Int. J. Miner. Process, 119 (2013), p. 27.
G. Ofori-Sarpong, K. Osseo-Asare, and M. Tien, “Mycohydrometallurgy: biotransformation of double refractory gold ores by the fungus, Phanerochaete chrysosporium”, Hydrometallurgy, 137 (2013), p. 38.
A. S. Adam, G. Ofori-Sarpong, and R. K. Amankwah, Assessing the challenges in the extraction of gold from bacterial-treated double-refractory concentrate”, [in] Proceedings of the SME Annual Meeting, Feb. 19 - 22, 2017, Denver, CO, Preprint 17-014, p. 1.
Anon, BIOX Comparative Data, Discussion Session Survey, Unpublished Report, BIOX Users Conference, Jinfeng, China, 2013.
R. K. Asamoah, M. Zanin, R. K. Amankwah, W. Skinner, and J. Addai-Mensah, “Characterisation of Tectonic refractory gold ore”, Australasian Chemical Engineering Conference, Perth, W. Australia, paper no. 1104, 2014.
R. K. Asamoah, M. Zanin, J. Gascooke, W. Skinner and J. Addai-Mensah, Refractory gold ores and concentrates part 1: mineralogical and physico-chemical characteristics. Miner. Proc. and Ext. Metal. 2019a, p. 1.
R. K. Asamoah, M. Zanin, W. Skinner and J. Addai-Mensah., Refractory gold ores and concentrates part 2: gold mineralisation and deportment in flotation concentrates and bio-oxidised products, Miner. Proc. and Ext. Metal. 2019a, p. 1.
L. Lorenzen and van J. S. J. Deventer, The identification of refractoriness in gold ores by the selective destruction of minerals, Miner. Eng., 6 (1993), p. 1013.
V. M. Torres and R. S Costa, Characterization of gold ores and cip tailings using a diagnostic leaching technique, [in] Proceedings of XIX I. M. P. C. Precious metals processing and mineral waste and the environment, 4 (1995), Chapter 3, pp. 15.
R. P. Hackl, What to be aware of in cyanidation of Bio-oxidised products, Innovations in gold and silver recovery, Randol Gold Conference Phase IV, Sacremento, California, 1989.
K. Osseo-Asare, T. Xue and V. S. T. Ciminelli, Solution chemistry of cyanide leaching systems, [in] Precious Metals: Min., Ext. and Proc., The Metallurgical Society of AIME, Warrendale, PA, (1984), p. 173.
D. M. Hausen, and C. H. Bucknam, Study of preg robbing in the cyanidation of carbonaceous gold ores from Carlin, Nevada”, [in] Proceedings of 2nd Int. Congress on Appl. Mineral., AIME, Warrendale, PA, (1985), p. 833.
P. A. Schmitz, S. Duyvesteyn, W. P. Johnson, L. Enloe, and J. McMullen, “Adsorption of aurocyanide complexes onto carbonaceous matter from preg-robbing goldstrike ore, Hydrometallurgy, 61 (2001), p. 121.
W. T. Yen, R. K. Amankwah and Y. Choi, “Microbial pre-treatment of double refractory gold ores”, [in] Proceedings of the 6th Int. Symposium, Hydrometallurgy 2008, Phoenix, USA, SME, Littleton, CO, (2008), p. 506.
M. Márquez, J. Gaspar, K. E. Bessler and G. Magela, Process mineralogy of bacterial oxidized gold ore in São Bento Mine (Brasil), Hydrometallurgy, 83 (2006), pp. 114.
K. Sasaki, T. Sakimoto, M. Endo, and H. Konno, FE-SEM study of microbially formed jarosites by Acidithiobacillus ferrooxidans. Mater. Trans., 47 (2006), No. 4, p. 1155.
F. Habashi, Textbook of Hydrometallurgy, 2nd Edition, Metallurgie Extractive, Quebec, Canada, 1999.
M. Fantauzzi, C. Licheri, D. Atzei, G. Loi, B. Elsener, G. Rossi, and A. Rossi, Arsenopyrite and pyrite bioleaching: evidence from XPS, XRD and ICP techniques, Analyt. and Bioanalyt. Chem., 401 (2011), pp. 2237.
F. M. Gagliardi and J. D. Cashion “Mössbauer analysis of BIOX treatment of ores at Wiluna gold mine”, Hyperfine Interactions, Western Australia, 218 (2013), No. 1-3, p. 95.
M. J. Kruger, The importance of pH control in the biooxidation process, [in] Proceedings of the colloquium bacterial oxidation for the recovery of metals, Johannesburg, South Africa, 2000, p. 1.
D. E. Rawlings, Industrial practice and the biology of leaching of metals from ores, J. of Industrial Microbiol. Biotechnol., 20 (1998), p. 268.
H. Deveci A. Akcil and I. Alp, Bioleaching of complex zinc sulphides using mesophilic and thermophilic bacteria: comparative importance of pH and iron, Hydrometallurgy, 73 (2004), p. 293.
H. Tan, D. Feng, G. Lukey and J. Van Deventer, The behaviour of carbonaceous matter in cyanide leaching of gold, Hydrometallurgy, 78 (2005), p. 226.
J. W. Olivier, BIOX® Overview, BIOX Users Conference, Almaty, Kazakhstan, 2011.
R. Tippin, H. Bruce, L. Huiatt and D. Butts, Silicate mineral and potash flotation, Adv. in Flotation Technol., SME, Littleton, Colorado, 1999, p. 199.
A. S. Adam, Bogoso BIOX® Plant: An update on performance, challenges and opportunities, BIOX Users Conference, Johannesburg, South Africa, 2009.