Treatment Of Cyanide Tailings By Aneurinibacillus.sp JK-1 Induced Mineralization

China is rich in gold mineral resources.In the gold extraction process,cyanide leaching is the main gold extraction process with high recovery rate and strong adaptability.However,a large number of cyanide tailings will be produced during the gold extraction process,and the presence of the heap in the environment will often cause cyanide and heavy metal pollution in the surrounding environment.In this paper,microbial-induced calcium carbonate precipitation?MICP?technology is used to degrade cyanide while achieving the solidification of cyanide tailings and the stabilization of heavy metals.On the basis of investigating the relevant physical and chemical properties of cyanide tailings,the cyanide-reducing functions and Strains producing urease activity were investigated for their effect on enhancing the degradation of cyanide in tailings and the effect of inducing calcium carbonate precipitation on the solidification and stabilization of cyanide tailings and heavy metals in tailings.The main conclusions are as follows:Using cyanide-containing gold mine tailings as the source of strains,a strain with both cyanide-reducing and urease-producing activity was isolated and purified,which was named JK-1 and was initially identified as Bacillus thiamine.Through the study of cyanide degradation and optimization of MICP conditions,the best experimental conditions of the bacteria were obtained.After the tailings were treated by MICP,the total cyanide concentration in the tailings decreased from 37.84 mg/kg to 4.95 mg/kg.Through the analysis of unconfined compressive strength,the unconfined compressive strength of the solidified tailings solidified by MICP can reach up to 0.74 MPa,which can effectively resist wind erosion to a certain extent and reduce the diffusion of cyanide tailings.MICP curing cyanide tailings can promote the conversion of the exchangeable and organically bound states of Cu,Pb,Cr to a stable state,thereby reducing bioavailability and reducing environmental hazards.Comparing the SEM-EDS patterns before and after curing,the loose cyanide tailings particles before and after curing are cemented together by the self-adhesive force of calcium carbonate.Through FT-IR and XRD pattern analysis,CaCO₃ exists in the solidified tailings,and its crystal forms are mainly calcite,aragonite and vaterite.Using high-throughput sequencing technology,the changes of microbial community structure at the phylum and genus levels during cyanide reduction and solidification were analyzed.The results showed that Firmicutes became the dominant phylum in the treatment group;Aneurinibacillus in groups B and C may follow cyanide The decrease of the content makes the bacteria uncompetitive and accounts for a small proportion;the urease-producing bacteria Aneurinibacillus and the salt-tolerant bacteria Aerococcus in the group D added with the binding liquid have become the dominant bacteria.In addition,it was found that the metabolism of arginine in group D was significantly higher than that of the other three groups,which may be due to the excessive ammonia in the system caused by the addition of a large amount of urea.The strain eliminated the toxin through the mechanism of arginine metabolism to maintain pH stability and normal growth of the strain.