| This paper refered to various methods for determination of the content of tellurium and the speciation analysis method of tellurium in solutions. In this research, the effects of different pre-treatment methods on the determination of Te, Bi, Cu, Co, Sb, Ni and Se in low-grade tellurim ore by ICP-MS were compared. Meanwhile, it proposed a method for the determination of Te(IV) and Te(VI) by using KI with ascorbic acid as reducing agent, 1,10-phenanthroline and Fe3+ as anti-interfering agent and HG-AFS applied to analysis of the bio-leaching solution of Thiobacillus ferrooxidans on low-grade tellurium ore in the form of tellurium. In this laboratory, oxidized tellurium was reduced by using photo-synthetic bacteria-Rhodopseudomonas palustris screened early and the factors affecting the reduction were explored and the reduction conditions were optimized by response surface method. The main research contents and conclusions of this paper are as follows.(1) Study on the way of dissolution and determination of Te, Bi, Cu, Co, Ni, Sb and Se in low grade tellurium ore by inductively coupled plasma mass spectrometry. In the first, the method of electric heating plate digestion and high pressure tank digestion were used to dissolve two kinds of low grade tellurium ore obtained by flotation, then the metal element contents of Te, Bi, Cu, Co, Ni, Sb and Se in the samples were determined by ICP-MS. By comparison, the two solution methods had the characteristics of low detection limit, good accuracy and sensitivity. But the electric heating plate digestion method consumed more reagents and easy to cross contamination, the high pressure tank digestion consumed less reagents and the blank value was low. Thus, the high pressure tank digestion method was choosed for the pre-treatment of the sample in the study.(2) Study on method for analyzing the morphology of the tellurium in the bio-leaching solution of low grade Tellurium ore. Te(IV) and Te(VI) in the solution were determined by 2202-HG-AFS under its best working conditions, by using 0.01 % KI-Ascorbic acid as reducing agent, 0.05 % 1,10-Phenanthroline and 20 mg/L Fe3+ as anti-interfering agents. The detection limit was low to 0.209 g/L and the recovery rate was between 90.8-106 %. The method has the characteristics of high sensitivity, good selectivity, simple operation, good precision and accuracy for the speciation analysis of tellurium.(3) Study on the redox characteristics of photosynthetic bacteria in the oxidation of tellurium. Oxidized tellurium was reduced by using photo-synthetic bacteria-Rhodopseudomonas palustris screened in in this laboratory early. By means of scanning electron microscope(SEM), transmission electron microscope(TEM) and X-ray(XRD), Oxidized tellurium reduced into black elemental tellurium was confirmed.(4) Study on optimization of reduction conditions of oxidized tellurium by response surface method. The photosynthetic bacteria-Rhodopseudomonas palustris which has been capable of reducing oxidized tellurium to elemental tellurium and the reduction conditions were optimized by response surface method. Based on the single factor experiment, a four-factor-three-level experiment design which choosed reduction rate of tellurite as response value was developed by Box-Behnken central composite design method of Design-Expert. The results of two regression analysis showed the best combination. Under the culture condition about the light intensity of 1500 Lx, the optimal conditions of oxidized tellurium reduction were: 6 % of bacteria inoculation amounts, initial oxidized tellurium concentration at 95 mg/L, the initial pH value at 6.2 and culture time for 9 days, the reduction rate could reach 99.6 %.The results showed that the high pressure tank digestion method had good applicability for the analysis of Te, Bi, Cu, Co, Ni, Sb and Se in low grade tellurium minerals. HG-AFS can be used for large scale analysis and test, and meet the analysis of Te(IV) and Te(VI) in the bio-leaching solution of low grade tellurium ore.The photo-synthetic bacteria, namely Rhodopseudomonas palustris was used to reduce the oxidized tellurium and the response surface method was used to optimize the reduction conditions, and a higher reduction rate was obtained. The study provided a theoretical basis for the separation and recovery of tellurium from low grade tellurium ore by using micro-biological method. Compared with the conventional recovery process, the method was more suitable for the treatment of this kind of low grade complex minerals. It had the advantages of small environmental pollutions and high utilization rate of resources and it was in line with the idea of sustainable development. |
PDF Full Text Request