Breeding Of In-situ Uranium Leaching Strains And Its Application In Planting Test

Biological in-situ leaching of uranium ore is an important way and development direction for uranium resources exploitation.Biological in-situ leaching of uranium technology provides an effective channel for the development of low-grade,complex and difficult-to-leaching uranium resources.In the industrial application of bioleaching technology,it is found that a large amount of uranium leaching bacteria liquid is needed in the production of bioleaching uranium,and large-scale bacteria liquid production facilities need to be built on the surface.At the same time,the expansion of bioleaching technology is not conducive to mine safety and environmental protection.Therefore,it is necessary to select uranium leaching strains that can adapt to in-situ leaching and to study the optimal process conditions for in-situ leaching of uranium in the laboratory,so as to provide technical support and scientific basis for the regulation and optimization of in-situ leaching of uranium by in-situ bacteria.Based on the above problems,this paper isolated and purified strains with iron oxidation activity from drilling cores and groundwater samples of the 512 uranium deposit in Xinjiang.The strains were identified by morphological observation and 16sr DNA gene sequence matching method,and the physiological and biochemical characteristics of the strains in in-situ leaching tailings were studied.The strain was acclimated at low temperature according to the actual environmental factors of the ore layer,and it was applied to the high pressure tube fungus test,and the optimal planting conditions were analyzed.The following scientific research achievements have been achieved:A uranium leaching strain,Acidithiobacillus ferriooxidans（512SCK-Af-17）and its optimum growth conditions,which can be adapted to in-situ leaching environment,were developed.Through continuous transfer and domestication culture at 14～20℃,the maximum bacterial density in the two culture media can reach more than 10⁶cells/m L,and the iron oxidation rate in logarithmic growth period is greater than 0.07g/L·h,which basically solves the problem of poor iron oxidation activity of bacteria in low temperature environment.Under the inoculation condition of 30%,the indoor tube immersion test had the best effect.Under this inoculation amount,the time of iron oxidation of the strain could reach 32h at least,and the concentration of Fe²⁺in the tube decreased significantly.Statistical analysis showed that when the density of bacteria in the leaching solution was low（<10⁴cells/m L）,the iron oxidation activity of the strain was restricted by the dissolved oxygen environment.When the bacterial density in the leaching solution was high（>10⁸cells/m L）,it was mainly affected by the lack of energy substances.To sum up,this paper focused on microbial leaching of uranium as the main line,obtained the selected strain 512SCK-Af-17 by isolation and enrichment,purification and identification,and low temperature domestication,and expanded its culture as the leaching strain in the leaching solution,and applied it to the laboratory fungus test.The research results have important scientific value and practical significance for the control of bacteria in the in-situ bioleaching uranium mining flow field in the subsequent field experiments,improving the benefits of in-situ leaching uranium mining,and the industrialization and application of bioleaching uranium mining technology.