Harmless treatment of cyanide tailings by a bifunctional strain JK-1 based on biodegradation and biomineralization

• Published in: Journal of cleaner production 2021-09, Vol.313, p.127757, Article 127757
• Main Authors: Wang, Wei-da, Duan, Yao-ting, Wu, Yong-ming, Huang, Ying, Gao, Fu-wei, Wang, Zhe, Zheng, Chun-li
• Format: Article
• Language: English
• Subjects: Cyanide degradation; Cyanide tailings; Harmless treatment; MICP
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2021.127757

Cyanide tailings(CT) are a typical hazardous waste, containing large amounts of heavy metals and highly toxic cyanide. As so far, it is difficult to solve this problem at the same time. In this study, a “two-step” process was proposed for the first time to treat CT, first using microorganisms to degrade cyanide and then using microbially induced carbonate precipitation (MICP) to solidify the CT. We isolated a bifunctional bacterium which exhibited cyanide degradation and high urease activity from CT, identified as Aneurinibacillus tyrosinisolvens strain (named JK-1). We used JK-1 bacteria to treat the CT in a “two-step” process. The results showed that the degradation of free cyanide (F–CN) and total cyanide (T-CN) in CT by JK-1 bacteria reached 94.54% and 88.13%. After the MICP treatment, the spindle-shaped CaCO3 solidified the CT into a block of calcite and sphalerite crystals, and the uncompressed compressive strength (UCS) reached 0.74 MPa; the morphology of heavy metals in the CT changed from the exchangeable state to the carbonate-bound state, and the mobility was significantly reduced. Compared with chemical treatment, the treatment of CT by the new process is highly efficient and green, which can realize the solidification of CT, degradation of cyanide and immobilization of heavy metals at the same time. Compared with chemical treatment, the new process is efficient and green, which can realize the solidification of CT, the degradation of cyanide and the immobilization of heavy metals at the same time; it is of great significance to the harmless treatment of CT and the sustainable development of gold smelting industry. •A bacterium capable of cyanide-degradation and urease-production was isolated.•The new process can degrade cyanide, solidify tailings and stabilize heavy metals.•The bio-cement blocks of cyanide tailings were produced successfully.