| Tellurium resources as a national strategic reserve resources,each country began to pay an attention to the development and utilization of it.It was proved that there were lager lean tellurium ore and little rich tellurium ore in the independent tellurium ore area.The traditional technology could not develop it properly.In order to realize the rational development of tellurium ore,it was of great significance to carry out the research on the technology of microbial leaching of tellurium.In this paper,Primary tellurium ore of Shimian mining area was sdudied.Through the study on the activation and domestication of bioleaching bacteria,the pretreatment of ores and the optimization of leaching conditions had an influence on the effect of bacterial leaching,the optimum process of bacterial leaching of tellurium ore was determined.By using HFS and XRD to analyse the leaching amount of tellurium in the leaching solution and the phase composition of oxidized tellurium ore of three groups of experiences respectively,which were experiments of ferric iron oxidized Tellurium ore and bacteria oxidized tellurium and tellurium ore,the function of bacteria and ferric iron on the oxidation of minerals were investigated.By combining SEM and FTIR to analysis the changes of the surface morphology of slag and the situation of bacterial adsorption on the ore surface,the mechanism of bacterial leaching of tellurium ore was investigated.According to the characteristic of polyethylene glycol could improve the oxidative activity of bacteria and promote the dissolution of sulfide ores,the optimum mass concentration and relative molecular mass of the polyethylene glycol were obtained.with adding the optimum mass concentration and relative molecular mass of PEG,the effect of it on the bioleaching of tellurium ore was investigated.The main contents and results were as follows:(1)Study on leaching process of tellurium ore by Thiobacillus ferrooxidans.Through the activation of bacteria in the 9 K culture mediums and domestication of bacteria in the culture medium containing tellurite or tellurium ore pulp,the oxidation activity of bacteria was increased,the resistance of bacteria on tellurite were enhanced and the adaptation period of bacteria in tellurium ore pulp was shortened.The activated and acclimated bacteria could be used to leach tellurium ores.After acidizing the sample ore,the pH value of medium could be stabilized at around 2.0.When the temperature was 30 oC,pH value was 2.0,bacterial inoculum amount was 10 %,pulp concentration was 40 g/L,the rotate speed was 150 r/min,the leaching effect of bacteria on tellurium ore was the best.After 24 days leaching,the leaching amount of tellurium was 154.78 mg/L and the leaching rate was 47.77 %.(2)Preliminary study on the mechanism of leaching tellurium ore by Thiobacillus ferrooxidans.By using HFS and XRD to analyse the leaching amount of tellurium in the leaching solution and the phase composition of oxidized tellurium ore of three groups of experiences respectively,which were experiments of ferric iron oxidized Tellurium ore and bacteria oxidized tellurium and tellurium ore,it was concluded that ferric iron could oxidize the low valence tellurium to elemental tellurium,but it could't oxidize the tellrium to tellurous acid and telluric acid.Under the action of bacteria,the tellurium was oxidized to tellurium acid,so the tellurium was leached from tellurium ore.By combining SEM and FTIR to analysis the changes of the surface morphology of slag and the situation of bacterial adsorption on the ore surface,it was founded that ferric iron,a bacterial metabolite,had a certain erosion effect on the surface of tellurium ore and bacteria have certain adsorption on the surface of tellurium ore.(3)Study on the enhancement of leaching of tellurium ore by Thiobacillus ferrooxidans.According to studying on the effect of relative molecular mass and mass concentration of PEG on the bacterial oxidation of ferrous iron and dissolution of tellurium ore,it was obtained that when the relative molecular mass of polyethylene glycol was 2000 and the mass concentration of polyethylene glycol was 0.09 %,the dissolution of tellurium ore and the oxidation activity of Fe2+ by bacteria were the best.The effect of bacterial leaching of tellurium ore had been greatly improved by adding the best relative molecular mass and mass concentration of polyethylene glycol,compared with the bacterial group,after 24 days leaching,the leaching rate of tellurium was 83.91 %,the leaching amount of the bacteria increased by 1.45 and bacteria began to oxidize tellurium ore 3 days in advance.The results show that after the activation and domestication of Thiobacillus ferrooxidans,the bioleaching activity of the bacteria is improved,which can be used to leach tellurium ore.Through the optimization of the leaching conditions,the leaching effect of bacteria on tellurium ore has been improved.There is an indirect leaching mechanism in the process of bioleaching of tellurium ore,and the understanding of the process of bacterial oxidation can provide theoretical guidance for the further improvement of the leaching effect of tellurium ore.By improving the oxidative activity of bateria and increasing the dissolution of tellurium ore,polyethylene glycol enhances the oxidative effect of bacteria on tellurium ore.These research can provide theoretical basis and technical guidance for better development and utilization of primary tellurium ore resources in the future. |
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