Investigation of physicochemical parameters in drinking water resources and health risk assessment: a case study in NW Iran

In this study, the amount of cyanide in gold mine tailings is modeled as conceptual, statistical, and mathematical to determine environmental risk level and also to estimate the fate and transport of cyanide in tailings. Therefore, 116 points were selected for sampling from three levels of gold mine tailings and analyzed by colorimetric method. As a matter of fact, new hybrid modeling methods such as AdaBoost, Support Vector Machine, Linear Discriminant Analysis, and Random Forest were used in estimation. In current study, The AdaBoost method was qualified as the best one by minimum estimation error (less than 10%). The model derived from the AdaBoost method shows an average variation of 581 g/day in the volume of cyanide tailings. Thus, the important results of this paper are the presentation of 3D numerical and especially conceptual models according to the 3D cyanide variation in the sulfide gold mine tailings and governing physic/chemical parameters. These qualitative and quantitative results can be used for the management of tailings dam and prevention of the contaminant extension.     

某矿山天然放射性核素的调查

对某矿山工作场所和生活区分别进行了样品采集,并使用ORTEC公司生产的16000道HPGeγ能谱仪进行了测量。结果表明,该矿山工作场所天然放射性核素的比活度大多高于生活区,其中危害最大的为尾矿坝;某些生活区天然放射性核素的比活度比对照点和国家均值要高,但多数都在国家均值范围内,最高值出现在3号生活区的农田土样中,其天然放射性核素的比活度分别为：α（226^Ra）——750．4Bq/kg、α（232^Th）——91．5Bq/kg、α（40^K）——1202Bq/kg。     

金选矿厂含氰废水中氰化物降解及其环境风险评价

对陕西凤县四方金矿选矿过程中氰化物的迁移转化和降解进行了研究,结果表明,其尾矿库外排含氰废水氰化物浓度达到国家规定的排放标准。在此基础上对氰化物环境风险进行评价,为同类项目尾矿浆和尾矿水环境风险评价提供可信的基础数据。     

浅议上游法细粒尾矿堆坝问题

上游法细粒尾矿堆坝是尾矿处理技术遇到的难题之一。本文对细粒尾矿堆坝的不利条件进行了分析，通过和一般砂性尾矿堆坝条件的对比，讨论了二者在沉积滩形态、坝体剖面结构及土层力学性状等方面的差异对尾矿坝稳定性的影响。并就如何解决这一辣手问题提出了一些看法。     

精细地形下的尾矿坝稳定性及溃坝模拟分析

目前在尾矿坝稳定性和溃坝模拟分析方面,对溃口位置及水砂的流动状态难以做出准确判断。将尾矿坝稳定性和溃坝模拟有机结合,采用FLAC3D计算正常水位、洪水位、漫顶水位三种工况下尾矿坝稳定性,并利用Rhino与Fluent建立尾矿库及下游精细地形,开展尾矿库溃坝水砂在不同时刻及不同地形下的流动状态研究分析。结果表明:（1）浸润线的埋深随尾矿库水位的升高而变小,由正常水位升高至洪水位时浸润线埋深下降5～8 m,漫顶水位时坝顶浸润线沿坡面向下运移约8 m;（2）库水位对剪切带及尾矿坝稳定性有显著影响,从正常水位到洪水位时,剪切带纵向上不断向坝体内部延伸,横向上不断向坝脚延伸,剪切应变率增大为5.78×10?5,尾矿坝稳定系数由1.80下降至1.32;（3）达到坝顶时剪切带急剧缩短,而剪切应变率进一步增大为3.32×10?4,尾矿坝稳定系数由1.32下降到1.18。溃坝水砂的流动状态受地形影响明显,在山谷中表现为范围减小、流速增大的汇聚流动,在平坦农田处表现为范围增大、流速减小的发散流动特点。     

某尾矿坝毛细水带内的坝体材料物理力学特性研究

毛细水的存在将使尾矿坝坝体材料的物理力学特性发生较大变化,这种变化对尾矿坝的安全稳定势必产生影响,而国内外在此方面的研究工作却鲜有报道。为此,开展了某尾矿坝坝体材料现场取样、室内土工试验工作,并采用自制的毛细水带分层取样试验装置开展了长达6个月的毛细水上升测试工作,通过分层取样及土工试验,得到了毛细水带内尾矿砂的物理力学特性,进而系统地研究了毛细水带尾矿砂的含水率、重度、黏聚力、内摩擦角等物理力学指标随毛细水高度的变化特征。研究发现,毛细水带内尾矿砂的含水率和重度均随毛细高度而减小;黏聚力和内摩擦角的变化均随毛细高度和含水率呈先增大后减小的变化规律,其中内摩擦角的变化规律与以往相关研究所得结论并不完全相符,分析指出,这是由于毛细水和尾矿砂颗粒的表面特性所导致的;简要分析了抗剪强度随毛细高度的变化规律,发现其受毛细作用影响较大,呈先增大后减小的变化趋势。研究结果为坝体、边坡等工程的稳定性研究工作提供了一种新思路,为今后建立考虑毛细水作用下尾矿坝稳定性分析方法和理论奠定了基础。     

基于动力离心试验的软基尾矿库地震响应研究

基于离心机振动台,分别针对典型软基尾黏土尾矿库及加高扩容后的尾矿库开展了动力离心模型试验,重点探究了加速度分布规律、软土及尾矿内部孔压变化规律以及“软基?库内尾矿?尾矿坝”系统的变形规律等内容。试验结果表明：软基对地震动的放大效应较为微弱,而坝体加速度沿高程逐渐放大,高层子坝加速度响应最为强烈,加高扩容后的现坝顶加速度响应可达原坝顶的2.2倍;地震作用下软土与库内尾矿内部均会产生一定的孔压增量,但未达到液化状态。地震动强度、软基及库内尾矿的固结状态对尾矿库的变形模式影响较大。当固结不充分时,在强震作用下易发生尾矿的水平滑移,进而造成坝顶及下游软土隆起。在固结较为充分且地震动强度较弱的情况下,变形模式以震陷为主。该试验成果将为此类尾矿库的动力稳定分析及抗震加固设计提供一定参考。     

尾矿坝垮塌机制与溃决模式试验研究

基于云南拉拉铜矿小打鹅尾矿库工程设计资料,采用现场排放尾矿砂为试验材料,进行了尾矿堆积坝在洪水情况下发生垮塌破坏的模型试验。通过水流控制系统模拟尾矿坝遭遇洪水情况,采用侧面示踪点、水位测压管、应力传感器以及数码摄像机等设备获得了尾矿坝溃决过程中坝坡的位移矢量演化、浸润线与应力的变化特性以及坝体破坏发展过程,揭示了洪水作用下尾矿坝的垮塌机制和溃决模式。试验结果发现：尾矿堆积坝的浸润线变化存在滞后性;在洪水入库致库区最高设计洪水水位过程中,靠近坝坡中部处水平方向的总应力增量较垂向总应力增量大,增大的水平应力是坝体产生破坏的重要因素之一;洪水导致坝坡尾矿砂所受的渗透力、上浮力、重力以及孔隙水压力增大,削弱了坝体材料的黏聚力,并加大了自身荷载,降低了坝体的稳定性;尾矿坝溃决模式一般为逆流渐进型,破坏先是从坡脚处发生,继而向上游发展,呈现牵引式发展,破坏的滑动面由多个弧形滑移面构成。研究成果加深了对尾矿堆积坝垮塌机制和溃决模式的认识,并在洪水灾害的预防和控制方面作了一些新的探索     

中国农田土壤重金属污染防治现状与问题思考

土壤是农业可持续发展的基础。经过近40年的经济快速发展与农业高度集约化生产后,我国农田土壤污染与土壤环境质量下降问题逐渐凸显。当前,中国农田土壤重金属污染形势不容乐观,对农产品的安全生产和食品安全构成威胁。文章首先对我国农田土壤重金属污染现状与污染特点、农田重金属污染来源及修复技术研究现状等进行了总结。结果显示：(1)我国农田土壤重金属污染点位超标率相对较高,但以轻度污染为主;(2)污染土壤中主要以Cd、As、Hg、Pb和Cr这5种健康风险重金属元素为主,尤其以Cd风险最高,而以生态风险为主的Ni、Cu和Zn 3种重金属环境风险相对较小;(3)农田土壤污染分布总体表现为南方重于北方,东部重于西部;(4)农田土壤污染逐渐呈现由工业源向农业源、城郊向农村、土壤向食物链转移的发展趋势。基于文献计量方法对我国近30年来农田土壤污染防治研究的热点与趋势进行了分析。结果表明,我国农田土壤污染防治研究主要始于2000年前后,2009年后进入快速发展阶段,研究热点主要包括重金属污染监测、土壤环境环境质量评价、重金属污染土壤修复技术等,近10年来污染土壤修复技术表现为从单一修复技术向联合修复技术发展态势。此外,文章对我国农田重金属污染修复的一般程序、不同污染程度农田土壤的安全利用技术与高风险污染土壤的管控技术进行了评价,最后,对我国当前农田重金属污染防治过程中出现的问题进行了思考,同时针对我国今后农田重金属污染防治研究进行展望,提出了基于源头控制与风险管控措施相结合的农田重金属污染防治体系,以期为未来我国农田土壤重金属污染防治研究规划以及土壤重金属污染防治技术的创新提供参考与借鉴。     

Characterization of Kolar gold field mine tailings for cyanide and acid drainage

The gold mining process at Kolar gold field (KGF) mines has generated about 32 million tons of tailings. Gold was extracted from the mined ores using cyanidation technique that involved dissolution of gold in the ore by water soluble alkali metal cyanides (example, sodium cyanide or potassium cyanide). Of the several dumps that received the mine tailings only the Kennedy’s Line dump was active prior to closure of the KGF mines in the year 2000. The Kennedy’s Line dump received sulfide bearing tailings in slurry form that comprised of spent ore and process water bearing soluble alkali metal cyanide. Depending on the pH of the tailing slurry, the free cyanides may exist as aqueous hydrogen cyanide that can escape to the atmosphere as hydrogen cyanide gas or occur as soluble cyanide (CN⁻) ions that can be leached by infiltrating water to the sub-surface environment. Additionally, the presence of pyrite minerals in the Kennedy’s Line dump makes them susceptible to acid drainage. This study examines the potential of gold tailings of Kennedy’s Line dump to release cyanide ions (CN⁻) and acid drainage to the sub-surface environment by performing physico-chemical and leaching tests with tailing samples collected from various depths of the dump, sub-surface soil samples beneath the dump and groundwater samples from vicinity of Kennedy’s Line dump. The chemical mechanisms responsible for the ambient cyanide and pH levels of the tailing dump, sub-surface soil samples and groundwater are also inferred from the laboratory results.     

Effects of Poisonous and Harmful Elements Brought about by Coal Mining on Water Environment in Zibo Coal Mine, Shandong Province, China

INTRODUCTIONZibo lies in the center of Shandong Province,China.Thetopography of Zibo is high in the south and low in the north.Zibo is characterized by hills in the east,the south and thewest,and a wide plain in the north(Fig.1) .The annual rain-fall is 5 0 0 - 70 0 mm .The coal resources are very abundant in Zibo.There areXiazhuang,Xihe and Hongshan coal mines in the researcharea.The m ining sewage,about 0 .844 2× 10 8m3/ a,accountsfor about80 % of runoff of the Xiaofu River.The X…     

高浓缩分级尾矿上游法堆坝及模型试验研究

针对传统上游法尾矿库堆坝方法的缺陷与不足,提出了改进的上游法堆坝方法,即高浓缩分级尾矿上游法堆坝方法。基于尾矿库堆坝模型试验,以高浓缩尾矿堆存技术为指导,分别进行传统上游法和改进上游法的高浓缩尾矿堆坝模型试验,演绎尾矿库堆坝过程,测试并得出了堆坝过程中滩面尾矿沉积情况、尾矿颗粒分布规律及浸润线变化规律,并采用极限平衡法计算不同堆坝方式下坝体的最小安全系数。结果显示：高浓缩尾矿堆坝使沉积滩颗粒分布均匀,颗粒分级不明显,减少了互层和细泥夹层的出现,改善了坝体内部结构;改进上游法堆坝可以形成有利于排渗防洪的良好沉积滩滩型;稳定性分析结果表明,改进上游法堆坝方法可以使尾矿坝的稳定性提高19%～33%,研究成果可为新建尾矿库工程提供试验技术支撑。     

某磷石膏尾矿库堆积坝渗透稳定性分析

随着尾矿库堆积坝高度的增加,库内的地下水渗流场将发生改变,当尾矿堆积坝处的实际水力梯度大于临界水力梯度时,尾矿库堆积坝将产生渗透变形或失稳破坏。为了预测某已建磷石膏尾矿库堆积坝的渗透稳定性,本文运用地下水位计水位恢复试验去确定磷石膏尾矿渗透系数并计算水力梯度,同时采用Geo-studio软件中的SEEP/W模块分析磷石膏堆积坝在不同工况下的渗透稳定性。计算和分析结果表明当堆积坝处于945m堆积高程,在无干滩和100m干滩情况下,实际水力梯度分别为0.784和0.583;当堆积坝处于960m堆积高程,无干滩情况下,实际水力梯度为0.692,在以上两种情况下,堆积坝渗出点高程高于初始坝高程,堆积坝将出现流土变形,坝体处于不稳定状态。当堆积坝处于960m堆积高程100m干滩时,堆积坝上无渗出点,堆积坝处于稳定状态。分析研究结果对该尾矿库的安全运行和维护管理提供技术依据,同时为同类型尾矿库堆积坝渗透稳定性评价提供参考。     

古尔班通古特沙漠与绿洲交错带土地利用变化对土壤特性的影响

对比研究了古尔班通古特沙漠与绿洲交错带8种土地利用类型的土壤特性变化. 结果表明: 不同土地利用类型的土壤粉砂含量差异性显著(P<0.05). 人类活动干扰的时间越长、 强度越大, 粉砂和极细砂含量越高, 而细砂反之. 在人类活动干扰前期(≤5 a), 土壤养分与干扰时间成反比, 而后(＞5 a)与时间成正比. 不同土地利用类型的土壤养分分为4个等级: 1级为盐碱地, 为最高等级; 2级为生态防护林地、 荒草地和天然灌木林地; 3级为10 a农田地、 5 a菜园地和3 a农田地; 4级为5 a农田地, 为最低等级. 人类活动使得土壤盐分由原来的(盐碱土)上层高、 下层低转为上层低、 下层高. 而且盐分与干扰时间成反比. 土地利用变化的过程中, 土壤盐分与Cl^-、 SO₄^2-、 Ca²⁺、 Mg²⁺、 K⁺和Na⁺离子均成正比, 而与HCO₃^-离子成反比. 5 a农田地土壤退化指数(-30.58%)最高, 是其他土地利用类型的1.5~3.9倍.     

尾矿坝非饱和带滞水曲线模型的建立及应用

本研究的目的是建立一种简单实用的上游式尾矿坝非饱和带滞水曲线的数学模型。研究方法采用拟合法。在揭示了硬岩尾矿砂的沉积距离与含水率、孔隙比等之间关系的基础上,建立了一种arctanx的函数,用来表征含水率与基质吸力的关系。将本模型应用于降雨入渗条件下饱和-非饱和渗流场分析,结果表明,数学模型与实验数据,具有明显的一致性。研究表明:该数学模型函数简单,适用于上游式尾矿坝。     

地震作用下高堆尾矿坝永久变形与稳定性分析

综合采用时程分析法、整体变形分析法（等效节点力法和软化模量法）、极限平衡法等方法,以小打鹅尾矿库为例,分析了该高堆尾矿坝的永久变形和动力稳定性。分析了干滩面长度、尾矿堆积坝高度、设计地震加速度等影响因素对尾矿坝的安全系数和永久变形的影响,以及地震作用下尾矿坝安全系数的时程变化规律。结果表明：尾矿坝的地震永久变形与一般土石坝的存在差异,其水平方向的永久变形大于竖直方向的永久变形,且永久变形与坝高不一定呈单调递增关系;地震中尾矿坝的最小安全系数与各影响因素大体呈线性关系,而坝顶处的震陷与各影响因素之间呈非线性关系;地震过程中尾矿坝瞬时安全系数具有波动降低的特点,为此,完善了地震作用下尾矿坝最小平均安全系数的计算方法。该研究表明小打鹅尾矿库坝体的抗震性能能够满足相应抗震设防要求。     

A study on geotechnical characterization and stability of downstream slope of a tailings dam to improve its storage capacity (Turkey)

Tailings, waste products of the ore-dressing processes, are usually stored in a slurry form and pumped into sedimentation pond which is surrounded by natural heights and/or artificial walls. The database of International Commission of Large Dams and United Nations Environment Programme showed that several hundreds of tailings dam have failed since 1910. One of the reasons of these failures is slope instability. Construction of mine tailings dams in Turkey has started to increase, particularly in the recent decade. This paper focuses the study undertaken to assess the geotechnical characteristics and stability of downstream slope of a tailings dam at a copper-zinc mine in the Black Sea Region of Turkey. At the mine site there are two tailings dams located at two different elevations. The upper dam was completely filled and is out of service. Increasing amount of tailings filling the pond of the lower dam resulted in a limited storage, and therefore, it has been decided that heightening of the dam about 7 m to improve its storage facility would be necessary. For the purpose, a series of investigations in the vicinity of the tailings dam and some geomechanical laboratory tests were carried in conjunction with the use of empirical methods to determine mechanical properties of the current dam material, tailings and the rockfill material that will be used for heightening of the dam. The results of the static and pseudo-static stability analyses based on the methods of limit equilibrium and numerical modelling indicated that circular and non-circular failures are the most critical modes of failure for the dam and safety factor gradually decreases when the tailings rise up to a specific elevation in the pond. However, the ranges of the calculated safety factors from both methods are considerably similar and suitable for heightening of the dam by 7 m in terms of stability. The results suggest that any instability is not expected under both static and dynamic conditions after the current height of the tailings dam is increased by 7 m, if the slope geometry considered in the analyses is not changed and the tailings in the pond do not rise up to an elevation of about 475 m. In addition, magnitude of permanent settlement of the dam due to a probable earthquake was also assessed using two empirical methods and the results from both methods showed similar amount of settlements which were in tolerable limits.     

基于不同溃口形态的尾矿坝溃决泥浆流动特性试验研究

以云南玉溪矿业有限公司秧田箐尾矿库设计资料为依托,依据相似原则,采用重庆大学自行研制开发的尾矿坝溃决破坏模拟试验台,基于尾矿坝溃决的口门形态,探索了坝体在1/4、1/2以及全部瞬间溃决3种情况下的下泄泥浆流动特性。试验结果表明：（1）溃坝口门形态对下泄泥浆的冲击力、淹没范围以及演进规律有较大的影响;（2）泥浆在下游各特征过流断面处的演进规律具有较明显的龙头衰减过程,龙头速度较大,泥深以及泥浆冲击力呈现小-大-小的分布,具有较长的拖尾衰减现象;（3）随着溃口逐渐加大,泥浆在下游同一过流断面处的冲击力和泥深呈明显增大趋势,其增大趋势表现为非线性;（4）泥浆流态在下游90°弯道处发生强烈扰动,在弯道内侧出现涡流现象,而在外侧出现反射现象,瞬间全溃下泄泥浆形成的涡流范围和反射波强度较坝体1/2和1/4溃决情况明显;（5）受溃口形态影响,下泄泥浆龙头到达同一过流断面的时间也不同,全溃泥浆龙头到达下游同一过流断面处的时间远小于坝体1/2和1/4溃决情况。同时,随着溃口的不断减小,同一断面处泥浆冲击力峰值呈减弱趋势,到达峰值的时间也相应推迟。研究成果为不同溃坝口门形态下的尾矿坝溃决泥浆流动特性的深入认识提供了参考。同时,对指导矿山企业的防灾减灾工作具有重要的现实意义。     

Dispersion of tailings in the Knabena—Kvina drainage basin, Norway, 1: Evaluation of overbank sediments as sampling medium for regional geochemical mapping

Molybdenum mining in the Knabena—Kvina drainage basin (1918–1973) left more than eight million tons of tailings in two small lakes in the headwater area of the Knabena river. The piles, that reach above the water surface, were freely eroded until a dam was built to reduce the dispersion in 1976. Sampling of tailings and fluvial sediments took place almost 20 years later. Sampling media were natural sediment sources, 1-cm-thick slices of overbank sediments of various depths, material from the tailings pond, sandbars, stream sediments, fjord sediments, and integrated samples of floodplain surfaces (0–25 cm). In total 734 samples were collected. Chemical analysis (ICP-AES after aqua regia or HNO₃ extraction) showed that overbank sediments at a certain depth represent the pre-industrial trace metal concentrations within the drainage basin. The tailings and recent fluvial sediments were enriched in approximately the same element suite. The highest enrichment factors were obtained for Cu (8–53) and Mo (22–57). Fluvial processes in the tailings pond have probably selectively eroded fine-grained, low-density particles. Thus, coarse chalcopyrite may have been left behind, while molybdate associated with fine-grained particles may have been selectively entrained causing dilution of Cu and enrichment of Mo in the downstream fluvial sediments. In the sandbars, the highest Cu and Mo concentrations were found in fine-grained sediments downstream of a low-gradient reach that act as a bedload trap. On the floodplains, it is seen that the first areas to be inundated in a flood situation (proximal to the river and in depressions) have the highest metal concentrations. For regional geochemical mapping it is suggested that overbank sediment profiles along river reaches with a laterally stable or slowly migrating channel, should be sampled. In such floodplains, pre-industrial overbank sediments are usually preserved at depth. In case of laterally unstable reaches upstream of the sampling point, polluted and unpolluted sediments may be interlayered or mixed. Therefore, samples should be collected from various depths or sedimentary units in such profiles. A similar sampling strategy should probably be adopted to detect vertical migration of elements especially in areas with acid rain and low bedrock buffer capacity. To obtain high contrasts between polluted and unpolluted drainage basins, the overbank sediment profiles should be within the proximal part of the floodplain.     

四川会东老虎岩尾矿坝地震反应分析

应用有效应力有限元法研究了老虎岩尾矿坝在不同坝高时的应力水平、变形和孔隙水压力分布,以及遭到Ⅶ度地震作用时的反应.分析结果表明:在当前坝高情况下,无地震作用时尾矿坝处于稳定状态.在受烈度为Ⅶ度的地震作用下,尾矿堆积坝坝外坡和沉积滩面的堆积尾矿砂土在局部已经发生液化破坏;在封库坝高情况下,无地震作用时尾矿坝处于极限状态.在受烈度为Ⅶ度的地震作用下,尾矿坝坝外坡和沉积滩面的堆积尾矿砂土已发生大面积液化破坏.在地震作用下,老虎岩尾矿坝堆积尾矿产生液化破坏的主要原因是堆积坝体内浸润线的埋深较浅.对老虎岩尾矿坝必须加强排渗措施,使坝体内浸润线下移.