RECUPERAÇÃO DE METAIS DE EFLUENTES DE CIANÍDRICOS DE MINERAÇÃO DE OURO COM CATODOS DE AÇO INOXIDÁVEL AISI 304 E TITÂNIO
RECOVERY OF METALS FROM GOLD MINING CYANIDE EFFLUENTS WITH AISI 304 STAINLESS STEEL AND TITANIUM CATHODES
Dutra, Achilles Junqueira B.; Lemos, Flávio de Almeida
http://dx.doi.org/10.4322/tmm.2011.030
Tecnol. Metal. Mater. Min., vol.8, n3, p.191-196, 2011
Resumo
O presente trabalho apresenta um estudo comparativo entre telas de aço inoxidável e de titânio, como catodo, com vistas ao desempenho energético e às taxas de remoção de metais. Foram empregadas ferramentas estatísticas visando a identificação das variáveis significativas no processo de recuperação eletrolítica de ouro, prata e cobre e oxidação do cianeto de efluentes da mineração de ouro. Para uma solução sintética contendo, respectivamente, 0,5 mg/L de ouro, 7,5 mg/L de prata, 150 mg/L de cobre e 150 mg/L de cianeto livre. Empregando-se catodos de aço inoxidável após 180 minutos de eletrólise, foram obtidas remoções de cobre e prata em torno de 99,6% e 95,5%, respectivamente, além da completa remoção do ouro. Com catodos de titânio, nas mesmas condições, a recuperação de cobre foi de 99,3%, além de ter sido obtida uma completa remoção do ouro e da prata. Em ambos os casos, a oxidação de cianeto fica próxima a 99%. O consumo energético específico médio obtido com o catodo de titânio foi de 66,19 kWh/kg de metal, enquanto que, com o de aço inoxidável, foi de 88,29 kWh/kg.
Palavras-chave
Cianeto, Cobre, Efluentes, Processo eletrolítico
Abstract
This paper presents a comparative study between stainless steel and titanium meshes to be used as cathodes, aiming at high metal recovery rates and good energetic performance. Statistical tools were used in order to identify the significant variables in the electrolytic recovery of gold, silver and copper and cyanide oxidation from gold mining wastewaters. For a synthetic solution containing respectively 0.5 mg/L gold, 7.5 mg/L silver, 150 mg/L copper and 150 mg/L free cyanide, after 180 minutes of electrolysis. Using stainless steel cathodes copper and silver removals of 99.6% and 95.5%, respectively, were obtained besides the complete removal of gold. With titanium cathodes under the same conditions, the copper recovery was 99.3%, and a complete removal of gold and silver was obtained. In both cases, the oxidation of cyanide is close to 99%. The average specific energy consumption obtained for the titanium cathode is 66.19 kWh/kg of metal, while for stainless steel as 88.29 kWh/kg.
Keywords
Cyanide, Copper, Effluents, Electrochemical process
Referências
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12 KEPA, U.; STANCZYK-MAZANEK, E.; STEPNIAK, L. The use of the advanced oxidation process in the ozone + hydrogen peroxide system for the removal of cyanide from water., Desalination, v. 223, n. 1-3, p. 187-193, Mar. 2008.
13 DUTRA, A. J. B.; ROCHA, G. P.; POMBO, F. R. Copper recovery and cyanide oxidation by electrowinning from a spent copper-cyanide electroplating electrolyte. Journal of Hazardous Materials, v. 152, n.2, p.648-655, Apr. 2008.
14 SZPYRKOWICZ, L. et al. Comparison of the performance of a reactor equipped with a Ti:Pt and an SS anode for simultaneous cyanide removal and copper recovery. Electrochimica Acta, v. 46, n. 2-3, p. 381-7, Nov. 2000.
15 SPITZER, M., BERTAZZOLI, R. Selective electrochemical recovery of gold and silver from cyanide aqueous effluents using titanium and vitreous carbon cathodes. Hydrometallurgy, v. 74, n. 3-4, p. 233-242, Oct. 2004.
2 GÖNEN, N.; KABASAKAL, O. S.; ÖZDIL, G. Recovery of cyanide in gold leach waste solution by volatilization and absorption. Journal of Hazardous Materials, v. 113, n.1-3, p. 231-236, Sept. 2004.
3 DONATO, D. B. et al. A critical review of the effects of gold cyanide-bearing tailings solutions on wildlife. Environment International, v. 33, n. 7, p. 974-984, Oct. 2007.
4 AKCIL, A. Destruction of cyanide in gold mill effluents: biological versus chemical treatments. Biotechnology Advances, v. 21, n. 6, p. 501–511, Sept. 2003.
5 STAVART, A.; LEROY, C.; VAN LIERDE, A. Potential use of carbon felt in gold hydrometallurgy. Minerals Engineering, v. 12, n. 5, p. 545-58, May 1999.
6 BAKIR, Ű.; ÖĠǕTVEREN, Ǖ.; KOPARAL, S. Removal of cyanide by anodic oxidation for wastewater treatment. Water Research, v. 33, n. 8, p. 1851-1856, Jun. 1999.
7 ZHOU, C. D.; CHIN, D. T., Copper recovery and cyanide destruction with a plating barrel cathode and packed-bed anode. Plating and Surface Finishing, v. 80, n. 6, p. 69-78, Jun. 1993.
8 SZPYRKOWICZ, L. et al. Hydrodynamic effects on the performance of an electrochemical reactor for destruction of copper cyanide - Part 1: In situ formation of the electrocatalytic, Chemical Engineering Science, v. 60, n. 2, p. 523-533, Jan. 2005.
9 PLETCHER, D.; WALSH, F. C. Industrial electrochemistry, London: Chapman and Hall, 1990.
10 AGÊNCIA NACIONAL DE ENERGIA ELÉTRICA. Relatório de Consumidores, consumo, receita e tarifa média por região. Disponível em:
11 ADAMS, M.; LLOYD, V. Cyanide recovery by tailings washing and pond stripping”, Minerals Engineering, v. 21, n. 6, p. 501-508, May 2008.
12 KEPA, U.; STANCZYK-MAZANEK, E.; STEPNIAK, L. The use of the advanced oxidation process in the ozone + hydrogen peroxide system for the removal of cyanide from water., Desalination, v. 223, n. 1-3, p. 187-193, Mar. 2008.
13 DUTRA, A. J. B.; ROCHA, G. P.; POMBO, F. R. Copper recovery and cyanide oxidation by electrowinning from a spent copper-cyanide electroplating electrolyte. Journal of Hazardous Materials, v. 152, n.2, p.648-655, Apr. 2008.
14 SZPYRKOWICZ, L. et al. Comparison of the performance of a reactor equipped with a Ti:Pt and an SS anode for simultaneous cyanide removal and copper recovery. Electrochimica Acta, v. 46, n. 2-3, p. 381-7, Nov. 2000.
15 SPITZER, M., BERTAZZOLI, R. Selective electrochemical recovery of gold and silver from cyanide aqueous effluents using titanium and vitreous carbon cathodes. Hydrometallurgy, v. 74, n. 3-4, p. 233-242, Oct. 2004.
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