Experimental Study Of Contaminants Release From Dump Leaching Tailings-water Interaction In Some Uranium Mine Of Guangdong

Uranium tailings are depleted uranium ore that the uranium of ore is extracted.Although the uranium of ore has been extracted (the extraction rate of uranium:65%~95%), there are still some uranium left in the tailings and tailings also contain otherradionuclides (such as226Th,226Ra). During the mining and smelting process of mine,large amounts of uranium tailings that are stacked on the surface, due to the highcontent and longer half-life of radionuclides in the tailings, and the radionuclides willbe moved to the surrounding environment, causing serious damage to the ecologicalenvironment by long-term effects of weathering and rain water, constitutes along-term radiological hazards of uranium mine. Therefore, the release rule ofcontaminants and the releasing kinetics analysis of uranium have been studied,providing a scientific basis for the management of uranium tailings and positiveimplications for environmental pollution control.In this paper, a uranium tailings pond in north of Guangdong province was takenas the research object. Using laboratory simulation, the rule of contaminants releasefrom tailings-water interaction and the characteristic of the releasing kinetics wasanalyzed. Through experiment, there are some conclusions as following:1、The results indicate that a large amount of H+, U and SO42-were released inthe process of tailings-water interaction.2、With the extension of immersion time, the cumulative release of contaminantsand the acidity of tailings soaking solution increased; the acidity reached maximumafter15d and the pH was3.30. The leaching rate of contaminants was very fast inearly stage and became remarkably slow in latter period.3、The smaller particle size of tailings, the higher concentration of dissolvedcontaminants. The releasing rate and concentration of contaminants decreased withthe increasing particle size. 4、The adsorption of uranyl on the surface of tailings is the main reason that the releasing rate of U is fast and influenced by the particle size of tailings.5、The kinetic equation (i+2(1-xt)-3(1-xt)2/3～kt) is used to describe the dissolution process of uranium in uranium tailing, and its dissolution velocity mainly depends on the rate of diffusion. The release rate will be decrease due to the particle size is too bigger or smaller.