Abandoned Mine Tailing Chemical Stabilization Of Heavy Metals

The exploitation and utilization metallic mineral has generated a lot of wastespollution, of which tailings produced the most. Large accumulation of tailings is not onlythe major hazard source of debris flow, but also taking up large tracts of land, moreover,the toxic heavy metals and other hazardous substances contained in the tailings will causesecondary pollution to the surrounding environment, ranging from polluted soil and waterto human illness through the food chain, which caused immeasurable loss. In order toeffectively implement the strategy of sustainable development, govern and research ondecrement and harmless of tailings must be carried out immediately.Based on above, this paper studies the selected abandoned lead-zinc mine tailings asthe study objective, as the result of outdated equipments and poor management, theefficiency of the beneficiation tailings is low and the content of heavy metal contained isgenerally high. Through comparison of technical solutions, chemical stabilizationtechnology is confirmed and three representative stabilizers: calcium oxide, sodium sulfide,sodium subsulfite and a new heavy metal chelating agent called ammonium dibutyldithiophhosphate are selected, by leaching toxicity experiments and comparing betweenoriginal condition and stabilization condition, the optimal dosage, liquid-solid ratio and pHare obtained, and stabilization mechanism are discussed; In order to study the mutualtransformation regulation of four forms of heavy metal, speciation analysis of heavymetals are done while each stabilizer at its best conditions comparing with original tailings.Studies show that heavy metal stabilization effects of heavy metal chelating agentammonium dibutyl dithiophosphate is significantly higher than others; moreover, with lessdosage and preferably of pH adaptability, it can greatly reduce leaching toxicity of Pb, Zn,Cd, Cr and closely meets the national standards of leaching toxic, but for Hg and As, thereis no obvious stabilizing effect. Calcium oxide can act well only at alkaline condition indecreasing Pb and Zn; sulfide is much useful treating Hg while adding a large amount ofdosage; sodium subsulfite seems no use towards these heavy metals; through chemicalforms analysis experiments, the acid extractable forms and reduction form of heavy metalsare converting to the oxidized form and slag form, which can reduce the bioavailability andimprove environmental friendliness. These results provide technical support and securityguarantees for the tailings and reclamation.