Research On Stabilization Control Of Acid And Heavy Metals Contaminated By Sulfide Ores By Sulfate Reducing Bacteria

The accumulation of sulfide ore waste produced during the mining process of sulfide ores will cause serious pollution to the environment.Sulphide minerals are accumulated in the waste rock field.After long-term natural oxidation,rainwater leaching and aerobic bacteria,the oxidation reaction occurs and a large amount of acid mine wastewater is produced.The heavy metals（As,Cu,Cd,Pb,etc.）released with acid waste water migrate into the sediments and soil of the water body of the mining area,and pollute the surrounding environment of the mining area,which seriously endangering the health of the human body.At present,microbioremediation has the advantages of thorough treatment,stable process,low cost of treatment,and removal of many heavy metal ions,and comes into the field of vision.In this paper,the composition and potential pollution of sulfide ore are analyzed,then the natural conditions of sulphate reduction and alkali production are simulated on the basis of sulphate reduction and alkali production.Column experiments are carried out to explore the effect of sulfate reducing bacteria on the remediation of waste stone under different experimental conditions.The main achievements are as follows:The material used in the experiment is sulfide ore waste and the purchased pyrite ore.The X-ray diffractometer is used to make a semi quantitative analysis of the samples by X ray diffraction.The mineral composition of waste rock is mainly Magnesium Calcite（Mg0.06 Ca0.94）CO₃,and its content is 74.8%.The waste rock is acid consuming ore.The mineral composition of pyrite ore is mainly Marcasite（FeS₂）,and its content is 77.8%,which is difficult to leach.In the environment of pH 1.5,sulfide ore waste is more easily oxidized than pH in 2.5 or 5.5 environment.Low pH environment is not only beneficial for chemical leaching,but also for bioleaching.A.f is suitable for growth in low pH environment,and pH is 1.5,which is beneficial to the growth and reproduction of oxidized bacteria represented by A.f,and its growth and metabolism activities promote the oxidation of sulfide ores.The study showed that the lower the pH,the higher the concentration of sulfate,Fe²⁺,Fe³⁺ and heavy metal Cu and Pb.When pH is 5.5,the leaching concentration of each metal ion is basically 0 mg/L.When pH was 5.5,the concentration of each metal ion leaching was 0 mg/L,but the concentration of SO₄^2-in the solution was still at a high level and could reach 800mg/L,indicating that the content of soluble sulphate in the waste stone was higher and soluble in water.Therefore,when pH is 5.5,Fe,Cu,Pb and As ions almost have no leaching and little oxidation reaction,but SO₄^2-content in solution is relatively high.Different initial Fe³⁺ concentrations have different effects on the leaching effect of waste rock.At the time of pH 1.5,the higher the initial Fe³⁺ concentration in the initial stage of the experiment,the more favorable for the oxidation of sulfide ore,the higher the concentration of sulphate and metal ions,but with the experiment,the growth of microbes will be inhibited by the high concentration of Fe³⁺.The precipitation of Fe³⁺ has a hindering effect on the surface of the waste stone particles by microorganism adsorption,which affects the direct oxidation leaching process of bacteria,thus inhibiting the oxidation reaction of the sulfide ore.But in general,the participation of microorganisms is beneficial to the oxidation reaction of sulfide ores.But in general,the participation of microorganisms is beneficial to the oxidation reaction of sulfide ores.Therefore,the content of SO₄^2-in the final solution is different,no initial Fe³⁺ bacteria > 0.2mg/L initial Fe³⁺ has bacteria > 0.4mg/L initial Fe³⁺ has bacteria > 0.8mg/L initial Fe³⁺ has bacteria > 0.8mg/L initial Fe³⁺ asepsis.The natural condition of the mine is simulated,and the pollution of waste rock and pyrite is repaired based on sulfate reducing bacteria.After SRB inoculation,the concentration of SO₄^2-in the effluent of the experimental column decreased and the sulfate removal rate was different in different experimental conditions.For sulfide ore waste remediation research:The average removal rate of sulphate for SRB in aerobic environment is 65%,and the average removal rate of sulfate to sulfate in anaerobic environment is 68.1%,and the average removal rate of sulfate is 59.6% in the presence of aerobic bacteria and in aerobic environment.The results showed that the simple inoculation of SRB was more beneficial to the removal of SO₄^2-,and the difference in the removal rate of SO₄^2-in the aerobic and anaerobic environment was small,indicating that the facultative anaerobes in the SRB mixed bacteria could still give full play to the specific reduction effect in the aerobic environment and thus remove the sulphate in the solution.For pyrite ore remediation research: during the experiment,inoculated with SRB experimental column clogged,and SRB in aerobic environment had an average removal rate of sulphate of 42.2%.SRB can effectively reduce the concentration of SO₄^2-in the effluent,but when the concentration of SO₄^2-in the experimental column is high,theS₂-produced by SRB will react with the metal ions.Then the sulfide precipitation is produced and the filter core is blocked.The experiment can only be terminated and the experimental process can be affected.The pH in the column experiment is higher than that of the influent pH.The ore used in the experiment is acid consumption ore.It will not produce acid pollution in the short term.The process of acid production needs further long-term experimental exploration.The Eh reduction in the system of SRB inoculation is beneficial to the growth and reproduction of SRB and the oxidation of the ore.The heavy metal content of the experimental materials in this paper is not high,and the effluent pH is neutral.It is difficult for heavy metals to exist in the form of ion.Therefore,the risk of heavy metal pollution is low,which can be seen as no heavy metal pollution in the short term.