Impact of mining activities on soils in a semi-arid environment: Sierra Almagrera district, SE Spain

Field and laboratory-column studies were undertaken in order to investigate soil contamination derived from past mining activity in the Sierra Almagrera (SA) district in southeast Spain. The tailings, soil and sediment samples that were collected showed high concentrations of Ag, As, Ba, Cu, Pb, Sb and Zn when analyzed. The mean concentrations of these elements in the tailings were 29.8, 285.4, 54000, 57.7, 2687.5, 179.0 and 2269.0 ppm, respectively. In the soil samples these decreased to 14.3, 96.9, 24700, 37.5, 1859.1, 168.5 and 815.7 ppm, respectively. Geochemical analyses demonstrated high levels of As, Pb and Zn which were above the intervention values set forth in the Andalusian Regulations for Contaminated Soils for As (>50 ppm), Pb (>500 ppm) and Zn (>2000 ppm). Column experiments and mineralogical studies suggest that the dissolution of sulfates and other secondary phases, accumulated in soils and waste-sites during the dry season, acts to control the mobility of metals. The elution curves obtained from column experiments showed a mobilization of Ba, Cu, Pb and Zn, while a low mobility was seen for Ag, As and Sb.     

Germination,Growth, and Nodulation of Sesbania rostrata Grown in Pb/Zn Mine Tailings

Sesbania rostrata in pure and amended Pb/Zn tailings. About 90% of seeds of S. rostrata germinated in pure Pb/Zn tailings, which contained high concentrations of Pb, Zn, Cu, and Cd. Although seedling growth suffered from the adverse environment of Pb/Zn tailings, they became established on tailings stands, in the greenhouse, as well as on the actual tailings dam, and completed their life cycle in 4 months. Dry matter production and nitrogen accumulation was 3200 kg/ha and 69.4 kg/ha, respectively in the actual tailings dam. Applying inorganic fertilizer to Pb/Zn tailings led to no obvious improvement in growth and nodulation of S. rostrata, while tailings amended by river sediment or domestic refuse rich in organic matter improved the growth and nodulation of the species. Azorhizobium caulinodans survived and formed N-fixing stem and root nodules in S. rostrata grown in pure Pb/Zn tailings with a nodule biomass exceeding 300 mg fresh matter per plant.     

ENVIRONMENTAL IMPACT ASSESSMENT OF TAILINGS DISPERSAL FROM A URANIUM MINE USING TOXICITY TESTING PROTOCOLS1

ABSTRACT: Toxicity testing is a means of establishing the environmental risk of a uranium tailings release. It is valuable in designing tailings containment structures because it assists in setting acceptable levels of risk for the design. This paper presents details of toxicity tests of the tailings from Ranger Uranium Mine, Northern Territory, Australia. The results suggest that the non-radiological toxicity of the tailings is low. The environmental risk of a tailings release is more likely to be related to the physical impacts of the tailings, including infilling of billabongs and changes in the sedimentology of riparian ecosystems rather than their biogeochemical impact. Two major results were: (1) water from treatment with washed tailing fines were not toxic to Hydra viridissima, and (2) mixtures of washed tailings fines and natural floodplain sediment (overlying water or elutriates) were not toxic to Hydra viridissima or Moinodaphnia macleayi.     

基于重构相空间充填体变形规律的灰色预测研究

尾砂胶结充填体是非线性力学介质,其变形是能量耗散的复杂过程,必须研究其内在变形规律,才能正确预测采矿过程中充填体的稳定性.对不同配比的尾砂胶结充填体进行力学试验,得出了其应力-应变规律,对安庆铜矿高阶段充填体变形进行了监测.采用自适应滤波原理,研究基于重构相空间的测量数据去噪处理方法.用灰色理论研究充填体变形在相空间中相点距离的演变规律,建立了重构相空间的灰色预测模型.为减小预测误差,对预测结果采用残差模型修正.应用建立的模型,对安庆铜矿高阶段充填体变形进行分析,确定了采场合理回采周期.结果表明,充填体变形具有非线性混沌特性,不同配比的充填体表现出不同的非线性动力学行为,重构相空间能充分展示充填体变形的内在规律.     

降雨对尾矿库渗流场的动态影响

尾矿库能否安全运行的影响因素之一就是渗流问题。而降雨又是影响尾矿库渗流场的一个重要因素。运用ANSYS有限元软件的热力学模块建模,计算了3种干滩长度、3种降雨量及7种雨型,共计63种组合工况。分析计算发现,降雨时干滩长度越长,尾矿库出口节点渗透压上升越高。由此可知降雨时,如果尾矿库干滩面未做防渗排水防护措施,那么干滩长度越长对坝体的稳定越不利。建议尾矿库工程设计过程中考虑在干滩面设置防渗排水设施。     

基于三角模糊理论的尾矿库风险评价研究

根据尾矿库的特点和我国现行的尾矿库安全生产监督管理法律法规及标准规范的要求,构建了尾矿库风险评价指标体系。综合考虑评价指标对风险发生可能性及后果严重程度的不同影响来确定指标权重,同时考虑到权重确定和指标赋值中的模糊性和不确定性等问题,选用三角模糊理论建立了尾矿库风险评价模型,并以本溪某尾矿库为例进行说明。理论分析和实例计算表明,该方法对尾矿库风险评价有很好的适用性。     

降雨条件下尾矿坝饱和-半饱和渗流模拟分析

降雨条件下,由于渗透压力的存在,降低了尾矿坝坝坡的整体稳定性,可能产生坝体自身的变形和破坏,甚至导致尾矿库溃坝发生.针对某尾矿库,分析了降雨条件下对尾矿坝渗流及稳定的影响,运用饱和-非饱和渗流理论及降雨入渗理论,分析了尾矿坝渗流场的变化过程,根据计算出来的瞬态渗流场,利用非饱和尾砂抗剪强度理论,对尾矿坝的瞬态稳定性进行了分析.研究成果对于提高尾矿坝降雨条件下安全运行,降低尾矿库溃坝事故发生率具有重要意义.     

Electro-remediation of tailings from a multi-metal sulphide mine: comparing removal efficiencies of Pb,Zn, Cu and Cd

Sulphidic mine tailings characterised by high concentrations of heavy metals (Pb 3532?±?97?mg/kg, Zn 8450?±?154?mg/kg, Cu 239?±?18?mg/kg and Cd 14.1?±?0.3?mg/kg) and abundant carbonate (17%) were subjected to eight lab-scale electrodialytic remediation (EDR) experiments to investigate the influence of current density, treatment time and particle size on removal efficiency. Pb and Cu removal improved when increasing current density, while Zn and Cd removal did not. In contrast Zn and Cd removal improved by grinding the tailings, while Pb and Cu removal did not. At the highest current density (1.2?mA/cm²), 94%, 75%, 71% and 67% removal of Pb, Zn, Cu and Cd could be achieved, respectively, on grinded tailings in 28 days. Sequential chemical extraction made before and after EDR revealed larger oxidisable fractions of Zn, Cu and Cd, representing large fractions of sulphides, which was likely to be the main barrier to be removed as efficiently as Pb. This was in accordance with acid/base extraction tests in which Pb showed high solubility at both high and low pH (up to 65% and 86% of extraction, respectively), while considerable extraction of Zn (55%) happened only at low pH; and very limited extraction (<20%) of Cu and Cd occurred at any pH.     

基于时序InSAR的覆砂石尾矿坝形变演化研究

为解决目前采用在尾矿坝坝体及滩面覆盖砂石进行防尘治理与闭库，但传统监测手段难以实现坝体整体监测的问题，采用时序InSAR技术对2014年10月至2018年7月的Sentinel-1A影像进行处理，提取了对应时间段内卡房尾矿坝的形变信息，并结合实地调查及尾矿坝建设资料，研究了卡房尾矿坝的时序形变演化规律。结果表明:SBAS InSAR监测到坝体出现第1次异常形变加速运动时间与坝体开始铺设砂石工程的施工时间节点完全吻合，体现SBAS InSAR技术在受人为工程影响的坝体形变监测方面具有极高的敏感性。坝体在施工结束后，坝体形变加剧趋势并未缓解，并且出现2次加速现象，分析认为是由于在坝体铺设约2 m厚的碎砂石极大地增加了坝体荷载，打破了坝体原有的应力平衡状态，且识别出雨季对坝体形变影响显著，表明铺设砂石会使得降雨在坝体中的停滞时间加长，进一步引发非雨季期间坝体形变加剧。研究结果不仅能还原坝体出现异常形变的时间与演化过程，而且还可以对引起异常形变的内在影响因素进行分析与论证，对指导尾矿坝灾害识别、分析与治理具有重要的指导意义。     

铜陵市铜尾矿土壤动物群落生态研究

对安徽省铜陵市铜尾矿地6种生境中土壤动物群落进行野外调查和室内分析，研究不同弃置堆放时间的铜尾矿地土壤的动物群落结构及其与尾矿基质理化性质、植被状况等生境条件之间的关系。结果表明，尾矿堆放时间、区位地貌和植被状况的不同，尾矿基质的理化性质发生变化，导致土壤动物的种类组成和数量分布具有明显差异。土壤动物在土体中的表聚性强，绝大部分集中分布于A层(0～5cm)；土壤的物理性质越稳定，土壤动物越丰富；土壤肥力越高，土壤动物越丰富多样。即尾矿地土壤的生境条件越优越，土壤动物群落的物种丰富度越大，个体数量分布越多，群落多样性越高。这些研究结论为尾矿区的生态修复和可持续利用提供了参考依据。