Effect of pyrite on thiosulfate leaching of gold and the role of ammonium alcohol polyvinyl phosphate (AAPP)

Liu, Xiaoliang, xu, bin, min, xin, Li, Qian, Yang, Yongbin, Jiang, Tao, He, Yinghe, and Zhang, Xi (2017) Effect of pyrite on thiosulfate leaching of gold and the role of ammonium alcohol polyvinyl phosphate (AAPP). Metals, 7. 278.

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Abstract

The effect of pyrite and the role of ammonium alcohol polyvinyl phosphate (AAPP) during gold leaching in ammoniacal thiosulfate solutions were investigated using pure gold foils. The results showed that pyrite catalyzed the decomposition and also significantly increased the consumption of thiosulfate. This detrimental effect became more severe with increasing pyrite content. Further, the presence of pyrite also substantially slowed the gold leaching kinetics and reduced the overall gold dissolution. The reduction in gold dissolution was found to be caused primarily by the surface passivation of the gold. The negative effects of pyrite, however, can be alleviated by the addition of AAPP. Comparison of zeta potentials of pyrite with and without AAPP suggests that AAPP had adsorbed on the surface of the pyrite and weakened the catalytic effect of pyrite on the thiosulfate decomposition by blocking the contact between the pyrite and thiosulfate anions. AAPP also competed with thiosulfate anions to complex with the cupric ion at the axial coordinate sites, and thus abated the oxidation of thiosulfate by cupric ions. Moreover, the indiscriminate adsorption of AAPP on the surfaces of gold and passivation species prevented the passivation of the gold surface by surface charge and electrostatic repulsion. Therefore, AAPP effectively stabilized the thiosulfate in the solution and facilitated the gold leaching in the presence of pyrite.

Item ID: 52730
Item Type: Article (Research - C1)
ISSN: 2075-4701
Keywords: gold leaching; thiosulfate; pyrite; additives; passivation
Additional Information:

© 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

Funders: National Natural Science Foundation of China (NNSFC), China Postdoctoral Science Foundation (CPSF), Hunan Provincial Natural Science Foundation of China (HPNSFC), Open-End Fund for the Valuable and Precision Instruments of Central South University (VPICSU), China Scholarship Council (CSC)
Projects and Grants: NNSFC Grant No. 51504293, NNSFC Grant No. 51574284, CPSF Grant No. 2014M550422, HPNSFC Grant No. 2015JJ3149, VPICSU Grant No. CSUZC2017, CSC Grant No. 201606370128
Date Deposited: 27 Mar 2018 03:18
FoR Codes: 09 ENGINEERING > 0914 Resources Engineering and Extractive Metallurgy > 091403 Hydrometallurgy @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970109 Expanding Knowledge in Engineering @ 100%
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