The extraction of Pt, Pd and Au from an alkaline cyanide simulated heap leachate by granular activated carbon

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• 作者：C.N. Mpinga ; S.M. Bradshaw ; G. Akdogan ; C.A. Snyders ; J.J. Eksteen
• 关键词：Precious metals ; Adsorption ; Granular activated carbon (GAC) ; Platreef
• 刊名：Minerals Engineering
• 出版年：January, 2014
• 年：2014
• 卷：55
• 期：Complete
• 页码：11-17
• 全文大小：846 K

文摘

Au(CN)2->Pt(CN)42->Pd(CN)42->Ni(CN)42->Cu(CN)32-It was shown that adsorption rates of precious metals within the first 60 min were very high, giving more than 90% extraction. Among the different adsorption parameters, nickel concentration had the most influential effect on the adsorption process followed by the adsorbent concentration. Adsorption of Ni was found to proceed at approximately the same rate as the precious metals, showing a recovery of approximately 90% in 2 h. The kinetics of Cu adsorption were slower, with less than 30% being recovered within the 120 min period. This suggests that the co-adsorption of Cu can be minimised by shortening the residence time. Adsorption of Fe was found to be less than 5%, while the recovery of Rh was negligibly small. The effect of thiocyanate ion concentration was not as important as the effect of free cyanide ion concentration but still had some influence. Under optimal (best) conditions, for a load cycle time of 2 h and 10 discontinuous loading cycles, the loading capacity of the activated carbon for PMs was observed to be 0.64, 0.66, 0.17 mg of Pt, Pd and Au/g of carbon, respectively.