Effect of Natural Zeolite on Pore Structure of Cemented Uranium Tailings Backfill

The use of some environmental functional minerals as backfill-modified materials may improve the leaching resistance of cemented uranium tailings backfill created from alkali-activated slag(CUTB),but these materials may participate in the hydration reaction of the cementitious materials,which could have a certain impact on the pore structure of the CUTB,thus affecting its mechanical properties and leaching resistance.In this paper,natural zeolite is selected as the backfill-modified material,and it is added to alkali-activated slag paste(AASP)and CUTB in cementitious material proportions of 4%,8%,12%,and 16%to prepare AASP mixtures and CUTB mixtures containing environmental functional minerals.After the addition of natural zeolite,the porosity of the CUTB generally increases,but when the content is 4%,the porosity decreases to 22.30%.The uniaxial compressive strength(UCS)of the CUTB generally decreases,but the decrease is the smallest when the content is 4%,and the UCS is 12.37 MPa.The addition of natural zeolite mainly reduces the number of fine pores in the CUTB,but the pores with relaxation times T_(2)of greater than 10 ms account for about 10%of the total pores,and there are a certain number of large pores in the CUTB.The main product of alkali-activated slag is calcium(alumino)silicate hydrate(C-(A)-S-H gel).When natural zeolite is added,the hydration products develop towards denser products with a high degree of polymerization and the formation of low polymerization products is reduced.This affects the internal fracture pores of the hydration products and the interface pores of the CUTB,has an irregular effect on the pore characteristics of the CUTB,and influences the UCS.

Geotechnical behavior of uranium mill tailings from Saskatchewan,Canada

This paper investigates the geotechnical behavior of uranium mill tailings from Saskatchewan, Canada.The 4% tailings were well-graded with 29% fines whereas the 5% and 6% tailings were gap-graded with 49% fines. All samples exhibited a negligible strength(0.4 k Pa) up to 60% solids, followed by a rapid increase. The 4% tailings exhibited a lower rate and amount of settlement than 5% and 6% tailings. The kidecreased from 10^(-2)to 10^(-4)m/s with a decrease in eifrom 16 to 4 and a decrease in ef from 8 to 4 such that 4% tailings showed one order of magnitude lower values than the 5% and 6%tailings. The settling potential decreased ten times(50%–5%) for 4% tailings and four times(60%–15%)for 5% and 6% tailings. The effective stress increased from 80 to 260 Pa in the settling tests. The 4%tailings were less prone to segregation when compared with 5% and 6% tailings. The average solids content after settling was 35% for 4% tailings, 40% for 5% tailings and 39% for 6% tailings with a solids content deviation of ±3%, ±8%, ±6%, respectively. All materials were essentially non-segregating at 40%initial solids.

Estimating Radon Flux and Environmental Radiation Dose from Decommisioning Uranium Mill Tailings and Mining Debris

Based on a case study on uranium mine No.765 of China National Nuclear Corporation (CNNC), the paper briefly describes disposal program and effect of decommissioning uranium mine/mill facilities and quantitatively evaluates radon fluxes and doses to man of gaseous airborne pathway from mill tailings and mining debris before and after decommissioning, including annual individual effective dose to critical groups and annual collective effective dose to the population within 80 km region of the facilities.

Multi-hierarchical fuzzy judgment and nested dominance relation of rough set theory-based environmental risk evaluation for tailings reservoirs

Environmental risk assessment of tailings reservoir assessment system is complex and has many index factors.In order to accurately judge surrounding environmental risks of tailings reservoirs and determinate the corresponding prevention and control work,multi-hierarchical fuzzy judgment and nested dominance relation of rough set theory are implemented to evaluate them and find out the rules of this evaluation system with 14 representative cases.The methods of multi-hierarchical fuzzy evaluation can overall consider each influence factor of risk assessment system and their mutual impact,and the index weight based on the analytic hierarchy process is relatively reasonable.Rough set theory based on dominance relation reduces each index attribute from the top down,largely simplifies the complexity of the original evaluation system,and considers the preferential information in each index.Furthermore,grey correlation theory is applied to analysis of importance of each reducted condition attribute.The results demonstrate the feasibility of the proposed safety evaluation system and the application potential.

Natural Radioactivity in Miscanthus floridulu Plant from the Uranium Tailing Pile at Guangdong, South China

Large amounts of uranium waste rocks and tailings resulting from the exploitation and treatment of uranium ore at the Northern Guangdong mine (South China) have been accumulated in dams (tailing ponds). To reduce the dispersion of natural radionuclides into the environment, some dams were revegetated with arbor, bush and sward. Besides these plants, Miscanthus floridulu is the dominant plant growing in some of the dams. The uptake and distribution of naturally occurring uranium (238U), thorium (232Th), radium (226Ra) and potassium (40K) by Miscanthus floridulu plant from different sample sites of uranium mine were studied under native conditions. The bioconcentration factors (BCFs) of soil to Miscanthus floridulu above-ground and root were calculated and observed to be in the range of 0.14 to 7.74 and 2.71 to 17.83 for 238U, 0 to 3.02 and 0 to 3.29 for 232Th, 0.15 to 79.76 and 1.01 to 50.22 for 226Ra and 3.00 to 8.41 and 2.69 to 11.22 for 40K, respectively. The transfer factors (TFs) of Miscanthus floridulu root to aboveground were also calculated and observed to be in the range of 0.01 to 0.73 for 238U, 0 to 0.99 for 232Th, 0.08 to 1.50 for 226Ra and 0.57 to 1.94 for 40K, respectively. The results showed that, Miscanthus floridulu is 238U and 226Ra-accumulating plant with significant absorption and accumulation characteristics.

Applied research of correspondence analysis method in waste tailings reservoir heavy metal pollution monitoring points optimization

In order to optimize monitoring points and monitoring factor, the relationshipbetween pollutants and soil sample were established by correspondence analysis.Thestudy results show that the reflecting monitoring points and monitoring factors in thegraphic on the same factor axis can clearly express the intrinsic link between pollutantsand monitoring points and distribution characteristics.To determine the main monitoringpoint and the main monitoring indicators can reduce and optimize the number of monitoringpoints under the premise of ensuring the typical and representative of monitoring data.Using the correlation of pollutants can reduce the number of monitoring indicators and improvethe effectiveness of data collection.

Radioecological Assessment of the Uranium Tailings in Tuyuk-Suu （Kyrgyzstan）

Radioecological Assessment of the Uranium Tailings in Tuyuk-Suu （Kyrgyzstan）. The aim of our research is the radioecological assessment of the current state of uranium tailings in Tuyuk-Suu. The methods of field and laboratory analysis were conducted with the modem radiological and nuclear physics equipment. Gamma survey was shown that the surface of the tailings Tuyuk-Suu and Taldy-Bulak may effectively reduce the exposure dose of gamma radiation, the body Tuyuk Suu is flooding with water flowing near the river in a concrete channel, so it should be constantly monitoring the state of the tailings and the river Tuyuk-Suu. In this article is given the analysis and estimates of the current radiation condition of the tailings dam and Min-Kush settlement. It was for the first time made the radiological analysis after closing of the uranium tailings in a body of the most tail material and it is estimated states possible pollution to environment.

尾矿的特性、灾害及其资源潜力

尾矿是矿石磨细选别后残余的固体废弃物,尾矿物理化学特性及尾矿库的常规地表堆存共同导致尾矿库存在较大的安全与环境风险。低品位矿体高强度开采趋势下,我国尾矿年排放量维持在10亿t以上的高位,累计堆存规模超200亿t,细粒尾矿堆存方式、潜在灾害防治及综合利用面临新挑战,采选新技术装备及政策利好因素推动尾矿资源潜力亟待释放。因此,以尾矿物理化学特性、排放堆存方法、溃坝灾害、尾矿资源潜力为主线,综述了尾矿物理化学特性、尾矿堆存形式、尾矿溃坝灾害防治等方面的研究进展,系统梳理了尾矿空区充填、尾矿制备材料、尾矿二次利用、超积累植物提取金属元素、尾矿固碳等资源综合利用方法,可为研究者及工业界系统全面地重新审视尾矿废弃物特性、尾矿库灾害防治、矿产可持续开发利用提供启示。

湖南某锡矿尾矿库周边土壤重金属污染特征及其来源分析

文章采用地质统计分析、污染指数法、地质累积指数法及潜在生态风险指数法对锡矿尾矿库周边表层土壤中Cd、Pb、As、Zn、Cu含量、分布及污染程度进行统计与分析,并采用相关性分析及主成分分析法对重金属来源进行定性描述。结果显示:(1)重金属平均值为Pb 398.70 mg/kg、Cd 5.97 mg/kg、As 1135.68 mg/kg、Cu 77.04 mg/kg、Zn 545.63 mg/kg,所有样品重金属含量均超过背景值;(2)尾矿库周边土壤为重污染,周边区域污染程度为西北>北侧>东侧>南侧>西侧,5种重金属均具有累积性,Igeo均值显示Cd>As>Pb>Zn>Cu;(3)地块综合潜在风险为极强风险,单项生态风险指数为Cd>As>Pb>Cu>Zn;(4)As、Pb、Cu、Zn存在极显著相关性,Cd与Zn极显著相关,与As、Pb显著相关。研究区土壤污染原因主要为干滩扬尘、地表漫流、废水泄露及渗漏,以及周边历史上尾砂及尾砂填埋影响等。

川西南某金矿尾矿库稳定性评价研究

通过现场勘查及室内试验,并基于二维有限元分析软件GeoStudio室内数值模拟,对川西南某金矿尾矿库进行渗流、应力应变和稳定性研究分析。结果表明:(1)尾矿库堆积坝孔隙水压力从上到下逐渐增大,正常工况最大为864.98kPa,最小为-173.27kPa,洪水工况最大为874.49kPa,最小为-182.27kPa。(2)正常运行时,堆积尾矿向水平方向最大沉积位移25cm,竖直最大沉积位移28cm;洪水运行时,堆积尾矿向水平方向最大沉积位移34cm,竖直最大沉积位移35cm。(3)尾矿坝在正常工况、洪水工况下和特殊工况三种工况条件下运行时,稳定性计算结果均满足规范要求。

中国北方盆地大规模铀成矿作用:地层篇

“红黑”耦合沉积建造是中国北方中—新生代盆地(简称北方盆地)砂岩型铀矿的重要控矿要素之一,在勘查实践中得到了广泛证实和应用,指导发现找矿靶区和矿产地300余处,在成矿理论方面取得重要进展。本文系统总结了北方产铀盆地的60万余米铀矿岩芯钻探成果,通过典型矿床赋矿层沉积学、地球化学等对比研究,系统分析了北方盆地侏罗系、白垩系、新近系等赋矿层形成的沉积环境、物质组成等,进一步明确了制约成矿流体运移、铀矿物沉淀的赋矿层条件。结果显示:①北方盆地自侏罗纪以来,发育了Ⅰ中侏罗世—晚侏罗世早期(Bathonian-Oxfordian)、Ⅱ早白垩世早期(Valanginian)、Ⅲ早白垩世晚期(Aptian)、Ⅳ晚白垩世早期(Cenomanian)、Ⅴ晚白垩世晚期—早古近纪(Campanian-Thanetian)、Ⅵ早新近纪(Aquitanian-Burdigalian)和Ⅶ晚新近纪(ZancleanPiacenzian)7期红层,与下伏富还原性组分的黑色层构成了典型的对偶沉积建造,为北方盆地大规模成矿奠定了赋矿层基础。②地球化学指标显示:红层中Fe^(2+)/Fe^(3+)比值介于0.29~1.47(n=78),黑层Fe^(2+)/Fe^(3+)比值介于0.57~53.96(n=223),赋矿层Fe^(2+)/Fe^(3+)比值介于1.00~26.45(n=52)。赋矿层、黑层Fe^(2+)/Fe^(3+)比值一般大于1,以发育黄铁矿、炭屑、油斑为特征,为相对较还原的环境。红层Fe^(2+)/Fe^(3+)比值一般小于1,以发育钙质结核为特征,为相对较强氧化的环境。③总有机碳含量显示红层为0~0.16%(n=107),含矿层为0.01%~2.65%(n=137),黑层为0.01%~2.66%(n=339),含矿层总有机碳含量略低于黑层,与铀矿的富集沉淀有密切关系。④砂岩型铀矿体呈“板状”或“楔状”产出于黑层顶部的灰色、灰绿色砂岩和细砂岩,甚至泥岩,红层为含氧含铀流体的运移通道,黑层为含氧含铀流体的富集沉淀的化学屏障。因此,北方盆地红层和黑层对偶沉积、旋回充填是大规模铀成矿必要的地层条件,这些认识打破常规思维,“红黑”旋回叠加导致了北方盆地多层成矿的现象,矿体一般呈板状就位于红层和黑层的过渡带,这对深入理解砂岩型铀矿成矿环境、成矿规律及成矿机理等工作和勘查工作部署具有重要实践意义。

高速铁路隧道下穿尾矿库开挖安全稳定研究

尾矿库是防止环境污染的重要环保设施,一旦发生渗滤液渗漏、溃坝等,后果极为严重。当隧道从下方穿越尾矿库时,对尾矿库安全稳定存在一定影响。依托粗铅、电锌及渣综合利用工程的配套尾矿库旁大羊山隧道穿越项目,开展隧道开挖方式及尾矿库堆载对于尾矿库安全稳定的研究。经地质预报和监控量测分析,在离尾矿库较远处隧道采用控制爆破开挖,近接范围内采用机械开挖。利用数值模拟软件FLAC 3D,分别建立隧道机械开挖数值模型与尾矿库三维数值模型以分析隧道机械开挖及尾矿库堆渣对地表沉降影响。结果表明,隧道开挖造成的地表沉降对尾矿库最大影响约2.08 mm,尾矿库堆渣本身造成的地表沉降约10 mm,隧道开挖造成的地表沉降值小于尾矿库堆渣造成的地表沉降值。因此,隧道开挖不会对尾矿库安全造成影响。

松辽盆地南部砂岩型铀矿储层结构与铀成矿作用

以松辽盆地南部DL地区砂岩型铀矿为目标,在沉积学背景研究的基础上,开展铀储层结构与铀成矿作用研究。通过钻孔数据统计及系统的取样分析并编制铀储层非均质性图件,精细地刻画了姚家组铀储层的几何形态和复杂结构,充分展示了铀储层的定量非均质性。结果显示,区内灰色砂体多为原生灰色砂体,而下氧化带在沉积期后经历了较强的表生流体改造,为后生氧化带,矿体主要分布于河道砂体分岔处,以及从无隔挡层到隔挡层突然变厚的河道砂体边缘而非河道中央,其形态受氧化还原界面控制以板状为主。综合分析认为,表生流体成矿作用经历了晚白垩世姚家组含矿主岩预富集与表生流体叠加改造成矿2个阶段。通过对比DL地区储层结构对铀成矿的控制作用,在BL地区优选出3片找矿靶区,为下一步的勘查工作提供理论依据。

铀尾矿库渗排水中氨氮电氧化去除影响因素研究

氨氮废水是全球水处理难点之一。在铀矿开采、选冶过程中会产生放射性固体废物并存储在铀尾矿库中,由于雨水的作用尾矿库产生大量废水,将有害物质浸出到水中形成渗排水,铀尾矿渗排水具有高盐、高氨氮、可生化性差、含较高氯离子的特点,现有方法无法有效处理此类废水。电氧化法可清洁高效地去除废水中的氨氮,氨氮去除率主要受Cl−浓度、极板材料、电流密度、pH等的影响。本文通过单因素实验对这些因素进行研究,通过正交分析,探索各因素对氨氮去除率的影响程度,根据影响程度由高到低排序为Cl−浓度>极板材料>电流密度;pH为次要影响因素,为电化学反应提供碱性环境。通过比较各条件对氨氮去除率提高的明显程度,推荐使用Ti/RuO_(2)-IrO_(2)-SnO_(2)电极组,其最优条件为Cl−浓度1000 mg/L、电流密度20 mA/cm^(2)、电解时间3 h、pH=9~11,在此条件下氨氮的去除率达100%,氨氮出水满足《铀矿冶辐射防护和辐射环境保护规定》(GB 23727—2020)和《污水综合排放标准》(GB 8978—1996)的要求。

铀矿尾矿氡射气系数测量方法及主要影响因素研究

放射性矿物以及放射性伴生矿物在开采过程中,由于岩石破碎处理,改变了矿石原有的物理结构,引起氡气射气系数和迁移特性的改变,造成尾矿氡气排放超标等环境问题。测定尾矿射气系数以及研究射气系数主要影响因素,对尾矿氡气防护与治理具有重要意义。本文以铀矿尾矿射气系数为研究对象,搭建了射气系数测量装置,并利用装置测量了不同粒径和温度条件下样品的射气系数。依据实验数据建立了射气系数与温度和粒径的关系和经验公式。实验结果表明,在5目~30目的粒径范围内,射气系数与样品成幂指数关系,随着样品粒径减小而增大;射气系数与温度存在正相关性,在20~40℃范围内,存在线性关系。得到的经验公式可用于铀矿尾矿氡气浓度模拟计算,为尾矿氡气治理提供基础数据。

电化学滤池处理铀尾矿渗滤液的效能研究

为高效、低碳处理铀尾矿渗滤液,研发了一种新型石墨基电化学滤池,以石墨颗粒为填料、碳毡为导电体,通过直流电源提供电压,蠕动泵驱动,自下而上将铀尾矿渗滤液通过不循环连续运行的滤池,实验探究施加电压和水力停留时间等操作参数对模拟含铀废水以及实际铀矿废水的铀去除效能。结果表明:4.0 V和10 h分别为电化学滤池处理铀尾矿渗滤液的最优电压和水力停留时间,该工况下铀的去除率可达到97%以上。采用场发射电子扫描显微镜及能谱(FESEM-EDS)、X射线光电子能谱(XPS)等对反应后石墨颗粒上的产物进行了表征,表征结果表明:铀均匀地分布在石墨颗粒表面,吸附-还原为铀去除的主要机制,铀回收产物以U(Ⅳ)和U(Ⅵ)的混合物的形式沉积于电极表面。同时,通过成本估算可得,利用本装置从铀尾矿渗滤液中回收铀的运行成本为176.6~587.5元/kg(以U计),远低于常规陆地铀资源开发成本,具备良好的经济性。

岩溶地区某尾矿库尾砂渗漏探查与治理

某尾矿库位于岩溶地区,雨季库区出现塌陷,且下游溶洞口尾砂泄漏,造成当地水土体污染。经现场调查及库区水文地质条件初步分析,认为库区岩溶塌陷导通岩溶管道是尾砂泄漏的主要原因。采用EH4连续电导率剖面仪与五极纵轴测深相结合的综合物探方法,先进行EH4探测,再在EH4圈定的异常部位进行五极纵轴测深,发现在库区岩溶洼地中间发育一条北东向断层及其次生构造,且沿构造附近地表以下80m范围内有大量低阻区,推测为库区的主要过水通道。采用地面帷幕注浆方法,利用钻探查清了尾砂渗漏的主要岩溶通道;利用理论公式计算确定了骨料投入量,并采用“投骨料-注双液浆-注水泥单液浆”的动水注浆技术对大型溶洞或岩溶管道进行了有效封堵。经帷幕注浆治理后,库区内未再出现塌陷情况,下游也未见尾砂泄漏。实践表明,综合物探探测技术与地面帷幕注浆方法能有效解决尾砂渗漏通道探查与治理问题,可为今后类似尾矿库渗漏治理提供借鉴。

基于改进遥感生态指数的尾矿库及周边区域生态环境质量分析

以广西武宣三里沙安尾矿库及周边区域为研究区,整合实测数据与遥感数据,在兼顾尾矿库及周边区域植被、地表湿润程度、地表温度及地表裸露度和建筑用地信息的基础上,考虑了选矿厂、尾矿库及周边区域的土壤重金属污染情况,将土壤重金属污染指标纳入遥感生态指数RSEI中,从而构建改进的遥感生态指数IRSEI,并结合移动窗口算法与主成分分析模型,构建了一种改进的遥感生态指数IRSEI_mw。结果表明:增加内梅罗综合指数有利于更精细地对金属矿区及周边区域的生态环境质量进行评估;相比于整体研究区,尾矿库内部生态质量整体较差,整个研究区内RSEI、IRSEI及IRSEI_mw的均值分别为0.53、0.52和0.58,尾矿库内三个生态指数的均值分别是0.29、0.27和0.22;相比RSEI及IRSEI,IRSEI_mw指数计算的区域生态质量结果的区分度有所增加,尾矿区内生态质量等级为差的区域范围大幅增加,尾矿区外部等级为优的面积大幅增加。总体而言,IRSEI_mw指数可有效量化尾矿库及周边区域生态环境质量,有利于更精细地对金属矿区及周边区域的生态环境质量进行评估。

塔中隆起F_(Ⅱ)21断裂带油气成藏过程与多相态成因

针对塔中隆起F_(Ⅱ)21断裂带奥陶系油气藏相态分布复杂问题,基于构造解析、地球化学的综合分析认为,原油密度、天然气干燥系数及气油比等参数的平面分布趋势与走滑断裂分段构造密切相关,翼尾构造带北部发育凝析气藏,南部依次发育挥发性油藏与原油油藏。F_(Ⅱ)21断裂带与北部拗陷富满、顺北地区原油生源相同,主要来源于下寒武统烃源岩。原油成熟度沿断裂带由北至南依次降低,断裂带北部主要为原油裂解气,中部与南部主要为干酪根裂解气。F_(Ⅱ)21断裂带经历多期油气充注,翼尾地堑部位为油气有利充注点,喜马拉雅期盐下原油裂解气的强烈充注改造是北部凝析气藏形成的重要原因,受古构造影响,晚加里东期与晚海西期生成的原油资源主要于翼尾地堑构造南部鼻状隆起区域聚集成藏。

基于清单制管理的尾矿库信息化系统研究及应用

针对尾矿库安全风险突出问题,通过引入清单制管理理念,并融入“北斗+”监测后台数据,设计了基于清单制的尾矿库信息化系统。系统设计围绕清单制管理信息化展开,通过现场调研与需求分析,梳理出符合企业实际的安全生产管理责任清单,并建立完整的清单管理体系。该系统在试点企业成功应用,实现了关键岗位人员职责明确、风险点及时反馈处理与闭环管理。系统能够主动推送工作任务至具体责任人,实现扫码巡查、履职与获取动态监测数据等功能,有效提高了工作效率,减少了工作人员的工作量,进一步提升了尾矿库的安全管理水平。