Synergistic detoxification by combined reagents and safe filling utilization of cyanide tailings

• Published in: Chemosphere (Oxford) Vol. 312; p. 137157
• Main Authors: Liu, Qiang, Luo, Yating, Shi, Jiyan, Wu, Zengling, Wang, Qiankun
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2023
• Subjects: Decyanation treatment; Engineering application; Gold recovery; Underground filling; Gold recovery; Decyanation treatment; Underground filling; Engineering application
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2022.137157

Cyanide tailings are the major hazardous wastes generated in the production process of the gold industry, which not only contain highly toxic cyanide, but also contain heavy metals with recycling value and other substances suitable for building materials or filling. These tailings are in urgent need of purification treatment and safe utilization. In this study, the impacts of treatment methods, types and combinations of reagents on decyanation effect were researched. Gold in cyanide tailings was recovered by flotation, and flotation tailings were used for filling after identifying the properties of solid waste. Results are as follows: (1) INCO method and 5 reagents (sodium sulfite, sodium persulfate, copper sulfate, ferrous sulfate and zinc sulfate) were selected for synergistic decyanation treatment, and cyanide concents in slurry and leaching solution were decreased to the minimum. (2) The gold recovery rate of the tailings through flotation was increased by 27.8% than without detoxification. (3) Flotation tailings were identified as general industrial solid wastes by leaching toxicity and toxic substance content analysis. (4) As filling aggregate, under the conditions of slurry concentration of 63% and cement-sand ratio of 1:6, the strength filling body of flotation tailings reached 1.32 Mpa after 28 days of maintenance. (5) This process and combined reagents were applied to engineering. The cyanide content in the leaching solution and the flotation recovery rate of gold were kept below 0.2 mg/L and above 60% respectively, and the strength of the filling body was stable to meet the requirements of underground filling. [Display omitted] •Different decyanation methods and reagents of cyanide tailings were researched.•Five reagents were screened for decyanation and their interaction mechanism was expounded.•Gold was extracted by flotation after detoxification and the gold recovery rate was much higher than that of non-detoxification.•Flotation tailings were identified as general industrial solid wastes for filling, and filling parameters were explored.•Efficient detoxification and full resource utilization of cyanide tailings were realized and applied to industry.