Migration And Influence On Surface Environment While Exploiting And Utilizing Phosphate Rock In Tuojiang Valley

Due to a high content of radionuclides, phosphate is considerably concerned in the various processes of exploiting and utilizing.Selecting four typical phosphate fertilizer plant in tuojiang valley as research object,this paper discussed the content and distribution of radionuclide in different products while the process of exploiring and utilizing phosphate,and figured out radionuclide migration destination in the process.Through surveying and sampling around the main river in tuojiang valley,influence on surrounding surface environment was studied in the process of exploiring and utilizing phosphate.Finally, migration path in the environment was summarized.Through research,the main results as follows:1) Radionuclides in phosphate transferred to phosphate fertilizer and subsidiary product feedgrade DCP and waste reside phosphogypsum and waste liquid Uranium mainly transferred to feedgrade DCP and waste liquid,and distributed more. Thorium mainly transferred to feedgrade DCP and enriched,and next shifted to phosphogypsum,and thorium distribution in extract liquor was seldom.2)Different processing and materials significantly affected radionuclides distribution in the phosphate fertilizer process. Uranium and thorium content of ammonium phosphate and feedgrade DCP from different phosphate fertilizer plant were different,but both of feedgrade DCP were both high.When radionuclide content of phosphate was obviously much higher,one of phosphate fertilizer subsequently increased,So phosphate of low radionuclide content should be used. There are lots of factors impacting on uranium and thorium migration in the phosphate fertilizer process,such as types of phosphate and ground level,types of acid,differences of process and so on,to affect the distribution in phosphorus products. 3)The ratios to thorium and uranium are even different in the phosphate fertilizer process,which is between 0.001 and 0.76.All of those indicated the chemical behaviors of uranium and thorium were quite different in the process from phosphate to phosphate fertilizer.4)The process of mining phosphate and producing phosphate fertilizer may improve radionuclide content of surface in the environment. Thorium content in soil and stream sediments, uranium content in wate of River Basin has high levels, mainly due to development of phosphate mining and processing.There is none phosphate mining and processing in the downstream after the three rivers convergence,and self-purification function of water,so,radionuclide content of surface decreased.5)The content of uranium is significantly higher than one of thorium in surface water,while the content of thorium in stream sediment and soil were significantly higher than uranium.The content of uranium in surface water is 2ug/g.The uranium is water-soluble and easy to move with the water flow,but also the thorium is non water-soluble and easyly sedimentary and soil enrichement. Due to adsorption,stream sediment and soil contain small amounts of uranium.6)During the development and utilization of phosphate,migration of radionuclides in the environment following such ways: phosphate→water (liquid)→soil; phosphate→P→soil→plant; phosphate→residue→water→soil; phosphate→feed→livestock supplements.In this paper, firstly,complete summarized the radionuclide migration during the development and utilization of phosphate and found that affect factors of radionuclide migration. Secondly, comprehensive survey and research of radionuclides content on the River Basin,this results can provide the basis of environmental protection.And based on this thesis, put forward practical protection measures, such as reasonable waste disposal,improving processing technology and strengthen supervision intensity to minimize environment radiation during the development and utilization of phosphate.