Abstract:There are cyanide, thiocyanate, metal-cyanide complexes, heavy metals and other composite pollutants in the gold mine heap leaching tailings, which seriously endanger the health of the surrounding environment. The microbial treatment of gold mine heap leaching tailings has the characteristics of low cost, high efficiency and low secondary pollution. It is a green and efficient treatment method, but the cyanide-reducing strain has a single function and has limitations. Therefore, this paper used a composite flora to treat the heap leaching tailings. A functional bacterium TCD-1 with heavy metal tolerance and cyanide degradation ability was screened, and its degradation performance of cyanide and metal-cyanide complex was studied. It was mixed with thiocyanate degrading bacteria TDB-1 and surfactant producing bacteria Z-90 to make a composite microbial eluent. The leaching process of compound bacteria in gold mine heap leaching site was established, and the optimum tailings particle size, optimum pH value and optimum bacteria liquid ratio were determined. Under the condition that the particle size of heap leaching tailings is 20 mesh, the pH value is 8, and the ratio of bacteria to liquid is TDB-1∶TCD-1∶Z-90=2∶1∶1, the treatment effect of thiocyanate and heavy metals in tailings is the best. The small-scale amplification test showed that the content of pollutants in the heap leaching tailings and leachate after leaching met the requirements of relevant standards.Finally, the eluent produced in the leaching process was deeply purified, and the residual metal-cyanide complex in the eluent was broken by the oxidation ability of hydrogen peroxide. At the same time, the flocculant was used to flocculate and precipitate the heavy metals, so as to achieve the effect of simultaneous removal of complex and heavy metals in the eluent.
