Mercury Formation Emigration Characteristics During The Treatment High Mercury Coal With Fungi

The release of heavy metal elements during coal mining and utilization will cause pollution to the surrounding environment.Mercury is one of the heavy metal elements in coal.Research on the distribution and release of its occurrence form has now become one of the key topics in the clean utilization of coal.Microorganisms can bioconvert coal,but there are not many reports of mercury migration during the conversion process.In present work,the high mercury coal in the Laoying Mountain(LYS)area of Guizhou is taken as the research object.Firstly,the fungi that have the function of dissolving and releasing mercury in the coal are screened and separated from the surrounding soil of the area,and then the factors and conditions for the release of mercury are screened and optimized The characteristics of mercury migration in the process of fungus conversion to coal were also studied.The conclusions of the presnt work are as follows:(1)LYS coal is a kind of high-ash low-sulfur 1/3 coking coal with mercury content reaching 300.02 ng / g.A fungus MH-3 with good leaching effect on mercury in coal was isolated from the soil.The leaching rate of mercury in 10 days was 83.79%.The results of 18 S r DNA showed that the fungus MH-3 was of the genus Aspergillus and Aspergillus The homology of Aspergillus flavus HQ393872.1 reached 99.9%.Therefore,the fungus MH-3 was named Aspergillus flavus MH-3.(2)Through the Plackett-Burman(P-B)and Box-Behnken(B-B)tests,it is concluded that the amount of coal added,surfactant and inoculation amount are important factors affecting the mercury leaching rate.After analysis of variance,the order of the three factors affecting Hg(ng / g),that is,surfactant>coal addition> inoculation.The optimal leaching condition is 3g coal addition,1% surfactant,10% inoculation amount,and the leaching rate of mercury under optimal conditions is 84.89%.(3)During the treatment of mercury by fungi,the p H value of the microbial leaching group was higher than that of the blank group.The changes of ORP and Ec were similar,and they all showed a trend of rising first and then falling.The leaching trends of various forms of mercury in coal are residue state> organic matter and sulfide combined state> oxide combined state> exchangeable state> carbonate combined state,and the leaching rates are 65.21%,77.08%,83.04%,88.42 respectively %,91.08%.The analysis of physicochemical properties of the residual coal showed that the content of volatile matter in the residual coal increased after leaching,the content of fixed carbon decreased slightly,the amount of nitrogen,oxygen and hydrogen increased by 0.84% and 1.28% and 0.52%,respectively,while the carbon content decreased by 2.04%.XRD analysis of residual coal showed that the mineral content remained basically unchanged,indicating that Aspergillus oryzae had basically no effect on the phase composition of LYS coal.Infrared spectroscopy analysis of residual coal showed that the main functional group structure of coal was not changed during the treatment of LYS coal by Aspergillus oryzae.