Study On Biological Leaching Test Of A Uranium Mine In South China And The Relationship Between Pore And Mineral Leaching

The pore characteristics in biological column leaching of uranium ore are closely related to the dissolution of minerals,and is one of the methods to explore the leaching mechanism of uranium and other minerals in biological column leaching.This paper selected 2.5～5 mm,5～10 mm and 2.5～10 mm uranium ore with different particle sizes,used CT scanning,SEM analysis and other techniques to study the characteristics of porosity changes in the leaching process,to analyze the uranium,calcium,magnesium and other elements in the leaching liquid,and the relationship between the elements and the pore characteristics.The main research results are as follows:(1)Static leaching and flask biological leaching experiments were conducted to study the leaching process conditions,indicating that particle size and acidity are the key factors which affecting uranium leaching,and the microbial inoculation quantity had influence on the leaching of uranium.The uranium ore of three particle sizes was leached for 360 hours under different acidity conditions.When the acidity of 30 g/L,with the uranium ore particle size is 2.5～5 mm,the concentration of leaching uranium is 171.9mg/L,and the leaching rate is 85.53%,the leaching effect is the best.At the same time,considering the economic rationality,20% of the inoculation amount was selected as the parameter of the later biological column leaching.(2)The results of biological column leaching showed that the particle size was the key factor affecting uranium leaching under the same spraying strength,inoculation ratio,acidizing acidity and other technological conditions.Under the acidity of 30 g/L,the spray strength of 15%,the bacterial inoculation ratio of 20%,and the leaching cycle is 70 days,in packing leaching columns,the uranium ore with particle sizes were 2.5～5 mm,5～10 mm,and 2.5～10 mm,respectively.The leaching rates of uranium were 89.38%,71.39% and 81.69%,and the leaching rates of slag were 83.40%,63.34% and 73.45%,respectively.(3)Using CT scanning technique,analyze the pore change characteristics of the original ore before and after acidification and after leaching of uranium.The results show that the dissolution and leaching of uranium and other minerals are related to the changes in pores of ore particles,the pore changes between particles are affected by the dual effects of gravity compression and chemical dissolution during the leaching process.After acid leaching of particles,the particle size of 2.5～5 mm,5～10 mm,2.5～10 mm,the average porosity in the particles increases by 0.0039%,0.0028%,and 0.0013%,and after bacteria leaching increases by 0.0024%,0.1049% and 0.025%.The average surface porosity between particles increased by 1.05% and decreased by 3.72% and 3.44% after acid leaching,and increased by 4.6%,0.65% and 3.69% after bacterial leaching.SEM analysis of single ore particle shows that the original ore particles are dense,After strong acid acidification,the micro-cracks is generated,and bacterial leaching further expands the micro-cracks,but at the same time,some precipitated crystals of minerals are generated,which is consistent with the calculation of the saturation index of the leaching solution gypsum and iron.