【作者】 郑阳华；

【导师】 王里奥；

【作者基本信息】 重庆大学 ， 环境工程， 2007， 硕士

【摘要】 重庆市矿产资源丰富,矿物种类繁多,矿产开采量较大,各类矿物除了含所需的矿用成分外,同时伴生有高于规定水平的天然放射性物质。由于伴生矿资源中含有较高水平的天然放射性核素,在开采、冶炼、加工和利用过程中,佯生矿中的天然放射性物质也将迁移、浓集和扩散,含有天然放射性核素的产品、废弃物也将对环境造成一定程度的放射性污染。因此,研究各种矿藏开发利用过程中的放射性环境污染现状将会为保障人群健康,提出放射性环境污染防治对策提供基础资料和科学依据。本文依托重庆市环保局课题“重庆市伴生放射性矿调查”,根据全市1643家煤矿单位和2830家非煤矿山资料,筛选出20个典型矿区作为研究对象。通过现场测量、采样和实验室分析,获得了矿物堆场γ辐射剂量水平、空气中氡-222浓度,以及矿物和周围土壤的镭-226、钍-232、钾-40放射性比活度、矿周围水(井水或矿井水)样品的总α、总β含量等方面的数据。研究结果表明,各矿区之间γ辐射剂量率水平差距比较明显,处在61 nGy/h-439 nGy/h之间,平均值为119.8 nGy/h,γ辐射剂量率最大值出现在南川吉兴煤矿。通过模型预测,各矿区γ辐射所致公众、职业照射有效剂量最大值分别为0.54 mSv/a、0.61 mSv/a,均未超过年剂量限值(1mSv/a、20mSv/a)。20个矿区氡浓度范围为8.29-617 Bq·m-3,平均值为83.55 Bq·m-3,内照射剂量预测结果表明,这三个矿区的公众(成人)的内照射剂量均超过了年剂量限值的要求,但职业照射年剂量没有超过限值。黔江天生桥煤矿、南川吉兴、南川市甄子岩铝矿矿物所含放射性核素中,Ra-226比活度明显高于对照点土壤中测量结果最大值,南川市甄子岩铝矿矿物所含放射性核素中Th-232比活度明显高于对照点土壤中测量结果最大值,矿区矿物所含放射性核素中K-40比活度均低于对照点土壤中K-40测量的平均值。通过20个矿区的初步研究,对部分放射性水平较高矿区进行了再次深入研究。结果表明,煤矿成品煤堆场和煤渣灰堆的结果明显高于尾矿堆、周围土壤、周围菜地,也高于环境对照点的结果最高值。空气中222Rn浓度呈现出较高水平的点位均分布于矿坑和矿井内。矿井流出水的总α、总β含量明显高于附近饮用水中的含量,而矿区饮用水中总α、总β含量又比矿区所属区县的城区饮用水中的含量高。论文探讨了伴生矿判定标准,建议按照内照射指数IRa=ARa/400,外照射指数Iγ=ARa/330+ATh/260+AK/3800计算,满足IRa≥1或Iγ≥2任何一个条件均确定为伴生矿。经计算检验,判定标准的应用效果非常好,空气γ辐射剂量率与外照射系数、内照射系数均在0.01的水平上显著相关;从计算结果看,南川吉兴煤矿的内照射指数为1.90,外照射指数为2.43,属于伴生矿范畴。本论文的创新点在于首次研究了重庆市各类典型矿区电离辐射水平,搞清了矿物开发利用过程中的放射性污染现状,与环境对照点进行了对比分析,预测了对公众和职业人员产生的照射剂量,并在国内创新性的探讨了伴生放射性矿的判别标准。更多还原

【Abstract】 Chongqing city is rich in mineral resources,and has a great variety and production in mineral。Besides contain demanded mineral component,all these minerals also associated some natural radioactive material which exceeds standard rate。because associated mineral contains natural radioactive nuclide in a higher level,in the processes of exploit、refining、machining、and utilized,these natural radioactive materials contained in associated mineral will be migrated、concentrated、and diffused,the product and waste which contains natural radioactive nuclide will also lead radioactive pollution to the environment in some degree。Therefore,the research on radioactive pollution present state in the process of mineral deposit exploit and utilize will supply basic data and science fundamental for protect human healthy and make radioactive pollution prevention policy。This dissertation is supported by the Chongqing EPA research subject《the investigation of associated radioactive mineral in chongqing》,according to 1643 coal minerals and 2830 non-coal minerals in whole city,seclect 20 typical mining area as research target。By means of field survey ,sampling and laboratory analysis,we abtained some data in these aspect:γradioactive-dose level in mineral deposit ground;Rn-222 concentration in air、Ray-226,Th-232and K-40 radioactive specific activity in mineral and ambient soil ;tatalα、βcontent in water around mine。Research result shows thatγ-radioactive dose rate difference in each mine is obvious,these data ranged in 61 nGy/h-439 nGy/h,the average value is 119.8 nGy/h,the maximalγ-radioactive dose rate occurres in Jixing mine of Nanchuan。By the model predictive,the maximal effectiveγ-radioactive dose in public and occupation is 0.54 mSv/a and 0.61 mSv/a,which all below year limited value(1mSv/a、20mSv/a)。Rn-222 concentration in 20 mines ranged in 8.29-617 Bq·m-3,the average value is 83.55 Bq·m-3,the predicted result of internal radioative dose shows that internal radioactive dose in these three mine all exceed year limited value,but year career radioactive dose is below limited value。Among all the nuclides in Tianshengqiao coal mine in Qianjiang,Nanchuan Jixing and zengzi rock and aluminum mine ,the specific activity value of Ra-226 is obviously higher than the maximal measurement value in soil of reference point,in Nanchuan zengzi rock and aluminum mine,the specific activity value of Th-232 is obviously higher than the maximal measurement value in soil of reference point,however,the specific activity value of all mines are general below the average value in soil of reference point。Through the preliminary research to the 20 mines,and deeper research in part of mines with the higher radioactive level。The result suggest that the value of store field for product of coal and coal cinder is obviously higher than tailing pile、ambient soil and vegetable plot,it also higher than the maximal value in environment reference point。The higher 222Rn concentration points are all distributed in pit and well of mine。Totalα,βcontent in mine water is obviously higher than drinking water in adjacent area,while drinking water in mine area is higher than drinking water in urban that mine belongs to。This dissertation discussed the identification criterion of associated mine,it suggests that based on the calculation formula of internal radiation index IRa=ARa/400 and external radiation exposure index Iγ=ARa/330+ATh/260+AK/3800,when it is satisfied IRa≥1 or Iγ≥2,then it is identified as associated mine。Through calculate verify,the result we gained is very good ,γ-radioactive dose rate is significant correlated in level 0.01 with internal radiation index and external radiation exposure index;according to the calculate result,the IRa of Jixing coal mine is 1.90,Iγis 2.43,the result indicates it belongs to associated mine。The innovation of this dissertation rest on first research to ionizing radiation level in all typical mines of chongqing,makes clear the radioactive pollution state in mineral exploiting and utilizing processes,then compared with environment reference point,predicted the radiation dose to public and professional personnel,and innovately discussed the identification criterion of associated mine in china。更多还原