铀矿冶地域土壤中铀污染特征及其环境有效性研究
发布时间：2018-07-25 14:42
【摘要】：铀(U)矿冶过程中产生了大量铀尾矿和铀废石。尾矿中易残留大量的化学杂质,其中包括大量的放射性元素铀。铀尾矿虽然做了相应的防护措施,但污染问题仍不断被报道。铀废石通常认为其放射性核素含量低,大多沿山谷露天自然堆放,一般不对堆场做防渗漏处置,故对铀废石堆产生的潜在环境影响尚未引起重视。本文以湖南某尾矿库和广东某花岗岩型铀矿山的废石堆周边土壤为研究对象。在尾矿堆表层取四个尾矿样,并在尾矿坝外的上下游分别采集了2条剖面(视作背景土壤)和3条剖面(视作潜在U污染土壤)。在废石堆采集四个废石样,同时在上、下游分别采集了2条剖面(视作背景土壤)和4条剖面(视作潜在U污染土壤)。简单分析和探讨了尾矿及废石中铀的释放能力;通过剖面间U分布特征的对比,定量估算了受污染土壤中外源U的输入通量;根据富集因子评价了土壤的污染程度;结合逐级化学提取技术,分析了U在土壤剖面的赋存形态(包括六个相态:可交换态(Ⅰ);碳酸盐结合态(Ⅱ);有机质结合态(Ⅲ);无定型铁锰氧化物/氢氧化物结合态(Ⅳ);晶质铁锰氧化物/氢氧化物结合态(Ⅴ);残渣态(Ⅵ))及其环境有效性(活性态(可交换态+碳酸盐结合态);潜在活性态(有机质结合态+无定型铁锰氧化物/氢氧化物结合态);惰性态(晶质铁锰氧化物/氢氧化物结合态+残渣态));探讨了U与pH、有机质、常量元素的相关性;通过本研究为铀矿冶区域安全评价提供参考,同时为土壤中放射性元素的监测和治理提供理论依据。结果表明:一、铀尾矿及铀废石中U含量普遍高于本底基岩,活性铀与潜在活性铀之和所占的比例都在60%以上(铀尾矿活性与潜在活性U所占的比例65.92%~96.02%,废石中的比例为65.99%~84.36%)。铀在铀尾矿及铀废石中释放能力相当,活性铀与潜在活性铀在一定条件下容易发生迁移,威胁周边的生态环境。二、根据富集因子对铀矿冶地域周边土壤进行评价,铀尾矿及铀废石堆对周边土壤均产生了显著的放射性污染(如近尾矿堆的Wp2土壤剖面中铀的平均含量在65.96μg.g-1,是背景剖面的17.36倍;废石堆周边土壤剖面Fp1中U含量平均值达4848μg.g-1,是背景剖面的660.5倍)。三、根据外源铀通入量及风化土壤中U的质量迁移系数表明:土壤中铀污染主要来自于污染源输入的外源铀。四、总体来看,铀尾矿及铀废石周边污染剖面距污染源由近及远铀含量呈明显减小趋势。污染较重的土壤剖面中,铀随着深度增加有减小的趋势,并在土壤中部易出现峰值。周边土壤活性铀距污染源由近及远土壤中活性态U所占比例增大,潜在活性态U所占比例降低。随着深度的增加不同土壤剖面活性铀有递减的趋势,而潜在活性铀有增加的趋势。五、铀尾矿及铀废石周边污染剖面中活性铀所占的平均比例均高于背景剖面,潜在活性铀除了污染最重的Fp1所占平均比例高于背景剖面外其余均低于背景剖面。六、总体来看,铀尾矿与废石堆周边土壤距污染源愈近,土壤中外源U的输入通量愈大,在近源区,大量的外源U优先在土壤表层聚集,随着远离污染源,逐渐转变为优先在土壤剖面的深部淀积。七、本文研究的7条污染剖面中,尾矿周边土壤剖面平均活性铀在40%以上,加上潜在活性铀近90%以上;废石堆周边土壤近半及以上的U为活性态,加之潜在活性态,近90%及以上。土壤在被污染的同时也变成了新的更具活性的污染源,对生态环境产生的影响应引起充分重视。八、土壤中U与pH、有机质、常量元素(SiO2、TFe2O3、P2O5等)有较好的相关性。
[Abstract]:A large amount of uranium tailings and uranium waste rocks have been produced in the process of uranium (U) mining and metallurgy. A large number of chemical impurities are easily retained in the tailings, including a large number of radioactive elements. Although the uranium tailings have been protected, the pollution problem is still reported. The potential environmental impact on the uranium waste rock pile has not been paid much attention to. In this paper, the soil surrounding the waste rock pile in a tailings reservoir in Hunan and a granite type uranium mine in Guangdong is studied. Four tailings are taken on the surface of the tailings pile and 2 sections are collected in the upper and lower reaches of the tailings dam. Background soil) and 3 sections (regarded as potential U contaminated soil). Four waste rock samples were collected from the waste rock pile. At the same time, 2 sections (as background soil) and 4 sections (regarded as potential contaminated soil) were collected in the lower reaches. The release capacity of uranium in tailings and waste rocks was briefly analyzed and discussed, and the comparison of U distribution characteristics between the sections was determined. The input flux of the source U in the contaminated soil was estimated. The degree of soil contamination was evaluated according to the enrichment factor. In combination with the step by step chemical extraction technology, the occurrence patterns of U in the soil profile (including six phases: exchangeable state (I), carbonate bound state (II), organic matter binding state (III), and amorphous iron manganese oxide / hydroxide junction) were analyzed. Combined state (IV); crystalline ferromanganese oxide / hydroxide bound state (V); residue state (VI)) and its environmental effectiveness (active state (exchangeable + carbonate binding state); potential active state (organic matter binding state + amorphous iron manganese oxide / hydroxide binding state); inert state (crystalline ferromanganese oxide / hydroxide bound state + residue)); The correlation between U and pH, organic matter and constant element, provides a reference for the safety evaluation of uranium mining and metallurgy, and provides a theoretical basis for the monitoring and control of radioactive elements in the soil. The results show that the content of U in uranium tailings and uranium waste rocks is generally higher than that of the base rock, and the proportion of the active uranium and the potential active uranium is 60. Above% (the proportion of uranium tailings activity and potential activity U is 65.92%~96.02%, the proportion of waste rocks is 65.99%~84.36%). Uranium is released in uranium tailings and uranium waste rocks, and the active uranium and potential active uranium are easily migrated under certain conditions and threaten the surrounding ecological environment. Two, according to the enrichment factor, the surrounding soil of uranium mining and metallurgy is on the soil. It is evaluated that uranium tailings and uranium waste piles have produced significant radioactive pollution to the surrounding soil (for example, the average content of uranium in the Wp2 soil profile of the near tailing pile is 65.96 mu g.g-1, 17.36 times the background profile; the average value of U content in the soil profile around the waste rock pile is 4848 mu g.g-1, 660.5 times of the background section). Three, according to foreign uranium The mass transfer coefficient and the mass transfer coefficient of U in the weathered soil show that the uranium pollution in the soil mainly comes from the exogenous uranium input from the source of pollution. Four. In general, the pollution sources of uranium tailings and uranium waste rocks are obviously decreasing from the near and far away from the pollution sources. In the middle of the soil, the peak value of the active uranium in the surrounding soil is increased, the proportion of the active state of the active state of U is increased, the proportion of the potential active U is reduced. With the increase of depth, the active uranium in different soil profiles has a decreasing trend, and the potential active uranium has an increasing trend. Five, uranium tailings and the surrounding pollution profiles of uranium waste rocks. The average proportion of active uranium is higher than the background section. The average proportion of potential active uranium, except the most polluted Fp1, is lower than the background section. Six. In general, the soil around the uranium tailings and the waste rock pile is closer to the source of pollution, the greater the input flux of U in the soil source, and a large amount of exogenous U in the near source area. In the 7 polluted sections, the average active uranium in the surrounding soil section of the tailings is over 40%, and the potential active uranium is over 90%, and the U around half and above the soil around the waste rock pile is active, and the potential activity is in addition to the potential activity. Seven The soil has become a new and more active source of pollution at the same time, and the impact on the ecological environment should be paid full attention to. Eight, the soil U and pH, organic matter, constant elements (SiO2, TFe2O3, P2O5, etc.) have good correlation.
【学位授予单位】：南华大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53;X75
本文编号：2144142
[Abstract]:A large amount of uranium tailings and uranium waste rocks have been produced in the process of uranium (U) mining and metallurgy. A large number of chemical impurities are easily retained in the tailings, including a large number of radioactive elements. Although the uranium tailings have been protected, the pollution problem is still reported. The potential environmental impact on the uranium waste rock pile has not been paid much attention to. In this paper, the soil surrounding the waste rock pile in a tailings reservoir in Hunan and a granite type uranium mine in Guangdong is studied. Four tailings are taken on the surface of the tailings pile and 2 sections are collected in the upper and lower reaches of the tailings dam. Background soil) and 3 sections (regarded as potential U contaminated soil). Four waste rock samples were collected from the waste rock pile. At the same time, 2 sections (as background soil) and 4 sections (regarded as potential contaminated soil) were collected in the lower reaches. The release capacity of uranium in tailings and waste rocks was briefly analyzed and discussed, and the comparison of U distribution characteristics between the sections was determined. The input flux of the source U in the contaminated soil was estimated. The degree of soil contamination was evaluated according to the enrichment factor. In combination with the step by step chemical extraction technology, the occurrence patterns of U in the soil profile (including six phases: exchangeable state (I), carbonate bound state (II), organic matter binding state (III), and amorphous iron manganese oxide / hydroxide junction) were analyzed. Combined state (IV); crystalline ferromanganese oxide / hydroxide bound state (V); residue state (VI)) and its environmental effectiveness (active state (exchangeable + carbonate binding state); potential active state (organic matter binding state + amorphous iron manganese oxide / hydroxide binding state); inert state (crystalline ferromanganese oxide / hydroxide bound state + residue)); The correlation between U and pH, organic matter and constant element, provides a reference for the safety evaluation of uranium mining and metallurgy, and provides a theoretical basis for the monitoring and control of radioactive elements in the soil. The results show that the content of U in uranium tailings and uranium waste rocks is generally higher than that of the base rock, and the proportion of the active uranium and the potential active uranium is 60. Above% (the proportion of uranium tailings activity and potential activity U is 65.92%~96.02%, the proportion of waste rocks is 65.99%~84.36%). Uranium is released in uranium tailings and uranium waste rocks, and the active uranium and potential active uranium are easily migrated under certain conditions and threaten the surrounding ecological environment. Two, according to the enrichment factor, the surrounding soil of uranium mining and metallurgy is on the soil. It is evaluated that uranium tailings and uranium waste piles have produced significant radioactive pollution to the surrounding soil (for example, the average content of uranium in the Wp2 soil profile of the near tailing pile is 65.96 mu g.g-1, 17.36 times the background profile; the average value of U content in the soil profile around the waste rock pile is 4848 mu g.g-1, 660.5 times of the background section). Three, according to foreign uranium The mass transfer coefficient and the mass transfer coefficient of U in the weathered soil show that the uranium pollution in the soil mainly comes from the exogenous uranium input from the source of pollution. Four. In general, the pollution sources of uranium tailings and uranium waste rocks are obviously decreasing from the near and far away from the pollution sources. In the middle of the soil, the peak value of the active uranium in the surrounding soil is increased, the proportion of the active state of the active state of U is increased, the proportion of the potential active U is reduced. With the increase of depth, the active uranium in different soil profiles has a decreasing trend, and the potential active uranium has an increasing trend. Five, uranium tailings and the surrounding pollution profiles of uranium waste rocks. The average proportion of active uranium is higher than the background section. The average proportion of potential active uranium, except the most polluted Fp1, is lower than the background section. Six. In general, the soil around the uranium tailings and the waste rock pile is closer to the source of pollution, the greater the input flux of U in the soil source, and a large amount of exogenous U in the near source area. In the 7 polluted sections, the average active uranium in the surrounding soil section of the tailings is over 40%, and the potential active uranium is over 90%, and the U around half and above the soil around the waste rock pile is active, and the potential activity is in addition to the potential activity. Seven The soil has become a new and more active source of pollution at the same time, and the impact on the ecological environment should be paid full attention to. Eight, the soil U and pH, organic matter, constant elements (SiO2, TFe2O3, P2O5, etc.) have good correlation.
【学位授予单位】：南华大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53;X75
【参考文献】
相关期刊论文 前2条
1 巫声扬;王德生;;川北陆相砂岩型铀矿床成岩与成矿过程中有机质对铀的富集作用[J];铀矿地质;1991年05期
2 孙赛玉;周青;;土壤放射性污染的生态效应及生物修复[J];中国生态农业学报;2008年02期
，本文编号：2144142
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