Study On Bioleaching Process And Mechnism Of Low Grade Vanadium-bearing Stone Coal

As one of important of vanadium mineral resource,the total reserve of vanadium-bearing stone coal is abundant.It is widely distributed in China.Vanadium is as isomorphism hosting in the crystal lattice of muscovite.This lattice structure is very hard to be broken down.The traditional roasting extraction processes have lots of prooblenms,such as high consumption of acid reagents and serious environment pollution.In this paper,the recovery of vanadium from vanadium-bearing stone coal using bioleaching technology was mainly researched by At f and B.M..We focused on two important scientific issues,which were the optimum bioleaching conditions and various strengthening principles.The main research results are:The study showed that the maximum leaching rate of vanadium was achieved 47.56%after 30d under the optimum conditions of initial pH 2.0,20g/L of pulp density,10%inoculums,12 g/L of initial Fe2+ using At.f.The maximum leaching rate of vanadium was achieved 44.31%after 30d under the optimum conditions of initial pH 6.0,20g/L of pulp density,10%inoculums,20 g/L of initial sugar using B.M..The mutation test of B.M.showed the best mutation method was utraviolet mutagenesis.The vanadium extraction with the mutant bacteria was increased about 7.86%;the content of metabolites of oxalic acid and citric acid was increased about 37.67%and 33.01%,respectively.The technology of thermal pretreating vanadium-bearing stone coal can strengthen the bioleaching process.The leaching rate of vanadium using B.M.and At.f was 92.62%and 60.63%,respectively.Compared with the bioleaching raw ore,the leaching rate of thermal pretreated stone coal was increased about 48.31%and 13.07%,respectively.Thermodynamic,SEM,FTIR and XRD analysis was carried out,and found that the oxidation reaction of organic matter,the pyrite and vanadium was spontaneous reaction,the layered structure of muscovite collapses and the content of residual fraction of vanadium decrease.It is the main mechanism of bioleaching of vanadium.The raw ore and roasted stone coal was leached by different bioleaching process,and the order of leaching rate is B.M.+At.f(94.27%,roasted stone coal)>B.M.(92.62%,roasted stone coal)>At.f+B.M.(85.54%,roasted stone coal)>At.f(60.63%,roasted stone coal)>At.f(47.56%,raw ore)>B.M.(44.31%,raw ore)>acid leaching(42.37%,roasted stone coal)>water leaching(18.36%,roasted stone coal).The surface of muscovite particles was covered with jarosite during the bioleaching of jarosite,which prevented the interaction beteen bacteria or its metabolite and mineral particles.The first leaching process was acted using B.M.,followed with At.f.It could avoid the inhibition effect of passivation layer on bioleaching efficiency.The results of our results can play a guiding role for the microbial technology of leaching vanadium-bearing stone coal and provide strong theoretical basis for utilization of low grade vanadium-bearing stone coal.