Since 1999, effluent from the closed Esperanca Gold Mine, in the district of Minas Gerais, Brazil, has been routed through a microbial treatment system designed by Boojum Research Ltd. The system consists of seven distinct ponds with a combined volume of about 900 m3. The design was based on a Boojum system tested at INCO’s Copper Cliff facility in Ontario (see ARUM). The process utilized was named ARUM Acid Reduction Using Microbes) which utilizes microbes in low redox sediments to transform sulfate and metal-laden effluents into more stable precipitates and raise the pH.
This microbial treatment system was built to receive abandoned mine portal effluent in the gold mining district of Nova Lima, Minas Gerais, Brazil. Construction of the system was completed in June 1999, consisting of four oxidation-precipitation-settling ponds and three microbial treatment ponds operating in series. The system started to function in October 1999. Ten tons (t) of raw potatoes and 4.5 t of whole sugar cane were added as organic carbon supplies to the three microbial ponds. The mine portal effluent flow volume averaged 0.6 L.s-1, increasing during the rainy season to 1.0 L.s-1. The portal effluent’s pH ranged from 2.5 to 3.5. The pH of discharge from the microbial limestone treatment ponds ranged from 4.2 to 7.2 in the October 1999 to June 2000 period. The system removed, on average, 37% to 87% of the monthly nickel load (0.6-1.7 kg), 77 % to 98 % of the monthly aluminum load (19 – 49 kg), 74% to 82% of the monthly zinc load (1.7 – 0.6 kg) and 78 % to 95 % of the monthly iron load of(71- 236 kg).
For a PDF, please send an email to: margarete.kalin@utoronto.ca
J8 Kalin, M. and W.L. Caetano Chaves, 2003. Acid Reduction Using Microbiology: Treating AMD Effluent Emerging from An Abandoned Mine Portal, Hydrometallurgy (71:1-2), pp. 217-255.
C94 Kalin, M. and W.L. Caetano Chaves, 2001. Acid Reduction Using Microbiology (ARUM) treating AMD effluent emerging from an abandoned mine portal, Proceedings of the International Biohydrometallurgy Symposium, IBS-2001, Biohydrometallurgy Fundamental, Technology and Sustainable Development, Part B, Ouro Preto, Minas Gerais, Brazil, September 16-19, pp. 289-296.