1. Zinc cyanide removal by precipitation with quaternary ammonium salts.
- Author
-
Liu, Qi, Zhang, Mingqing, Cao, Yijun, Peng, Biao, and Barvor, Joshua Bosco
- Subjects
- *
QUATERNARY ammonium salts , *METAL cyanides , *CYANIDES , *ZINC , *METAL tailings , *AMMONIUM salts - Abstract
• An advanced method for zinc cyanide removal based on precipitation. • 92.17% of cyanide and 88.86% of zinc could be removed using OTAB. • The process is effective when non-polar organic contaminants and <50 mmol/L salt are present. • Co-existed copper can be simultaneously treated. In gold-processing plants, the final tailing containing metal cyanide species is typically treated using various oxidation methods to produce the main source of process water, which is subsequently recycled to the upstream units, such as flotation units. In some gold-processing plants, a considerable amount of metal cyanide species such as zinc cyanide remains in process water, despite the cyanide destruction process. Because residual zinc cyanide complexes can depress gold flotation, the amount of process water must be decreased such that it can be recycled to a flotation circuit. Previous studies report that the critical concentration of zinc cyanide, measured based on the total cyanide concentration during flotation depression, is 0.4 mmol/L. In the present study, the feasibility of using quaternary ammonium salts to precipitate zinc cyanide complexes to less than the critical concentration was studied. The results showed that 92.17% of 60 mg/L of cyanide and 88.86% of 50 mg/L of zinc (molar ratio Zn/CN = 1:3) can be removed using 0.4 g/L of octadecyl trimethyl ammonium bromide at a pH of 10. The concentration of the residual CN cyanide was less than the critical concentration. This indicates that the abovementioned process is effective when nonpolar organic contaminants and moderate amounts of salt (<50 mmol/L) are present. This work revealed that the precipitation process can be used as an advanced treatment method for process water subjected to oxidation treatment. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF