Research And Safety Evaluation Of Leaching Desulfurization Of Iron Concentrate By Acidophilic Bacteria

As a raw material for the production of steel,iron ore has very important economic value in the smelting process.The level of sulfur content in iron ore directly affects the strength and quality of steel.Sulfur also harms blast furnaces.The emission of sulfur oxides will pollute the atmosphere.According to production regulations,the sulfur content in iron ore needs to be reduced to less than 0.5%.In this paper,acidophilic bacteria LM-1 and strain LM-2 were separated,and the iron ore concentrate was desulfurized under the conditions of 5%slurry concentration,10%bacterial inoculum,temperature 26?and rotation speed 160r/min.During the leaching process,periodically monitor the p H,SO₄^2-,Fe²⁺concentration and the utilization of various nutrients in the leaching solution;the sulfur content of the iron concentrate during the leaching process,and analyze the desulfurization efficiency of the two bacteria.Through scanning electron microscopy-energy spectrum analysis(SEM-EDS)and microscopic analysis of the elemental changes of the iron ore surface before and after the leaching of the bacteria,the desulfurization mechanism of the two bacteria is discussed.Finally,through the introduction of preliminary hazard analysis(PHA)and failure model and effects analysis(FMEA),the safety assessment of some processes of microbial desulfurization is carried out to improve the safety of microbial desulfurization operations.The results show that LM-1 is an acidophilic flora,and its dominant flora includes Phenylbacillus and Alicyclobacillus bacillus,and LM-2 is acidophilic Thiobacillus ferrooxidans(T.f bacteria).The desulfurization rate of the iron ore concentrate by acidophilic bacteria reached 79.8%,and the sulfur content dropped from 2.08%to0.42%;the desulfurization rate of the iron concentrate by T.f bacteria reached 45.7%,and the sulfur content dropped from 2.08%to 1.13%.During the desulfurization process,the concentration of anions and cations in the leachate showed an overall increasing trend.On the 20th day of desulfurization of acidophilic bacteria,phosphate starvation reduced the desulfurization rate of the bacteria.The calcium,magnesium and iron nutrient elements in the leachate are adequately supplied,and the acidophilic flora consumes a lot of phosphate.From the analysis of the morphology of the ore samples,it is concluded that the two kinds of bacteria have an oxidizing effect on the iron concentrate,and there is phosphorus enrichment in the sulfur-containing impurity phase of the ore samples.It is inferred that the bacteria may have a direct effect on sulfur.Iron vitriol precipitates on the sulfur phase where T.f bacteria acts,and Fe³⁺plays an indirect leaching effect.Through the introduction of pre-hazard analysis(PHA)and failure type and impact analysis(FMEA),the safety assessment of the microbial desulfurization process is carried out,and the safety risks of the mineral sample crusher and chemical storage are judged,and preventive measures are proposed to improve the safety of microbial desulfurization operation.