Column leach study 1: Heavy metal dissolution characteristics from selected copper mine tailings

Mill tailings collected from seven copper mine mill sites in the western United States were examined by researchers from the Bureau of Mines for metal dissolution properties using a column leaching procedure involving a formulated “western rain” leachant. Studies investigated effects of height of waste column, wet/dry cycle, and maximum leachability of waste tailings. Further studies on selected samples indicated that treatment of acid-producing tailings with chemical stabilizers such as phosphates and carbonates did not greatly affect mobilization of heavy metals leached from these samples. Increased metal mobilization from unsaturated columns was often associated with decreased leachate pH and increased sulfate production, but was not observed in all samples examined. Results from these and other studies suggest that the driving force for metal dissolution and/or acid formation in unsaturated mine tailings is the oxidation of metal sulfides by atmospheric oxygen. The maintenance of tailings at or near saturation or the exclusion of atmospheric oxygen appear to produce leachates of nearly constant to slowly decreasing metal concentrations with each subsequent leaching.     

Column leach study II: Heavy metal dissolution characteristics from selected lead-zinc mine tailings

Metal dissolution from tailings from six lead-zinc mine and milling sites in the western United States was examined by researchers from the Bureau of Mines using a column leaching procedure involving a formulated “western rain” leachant. This 2-year laboratory study included the effects of column waste depth, dry cycles with and without oxygen, and pore water evaporation. The results indicated that leachate metal concentrations gradually decreased with each leaching, but that the degree of enhanced metal mobilization from unsaturated tailings varied widely from waste to waste. Further studies on selected samples from this group of tailings demonstrated that the driving force behind enhanced metal dissolution is the oxidation of sulphide minerals by atmospheric oxygen during the evaporation of pore water from the columns of tailings. Leachates from water-saturated columns of these tailings gave pH values from 6.5 to 8.5; acid production and dissolved metal concentrations were enhanced by alternating wet and dry cycles. All studies to date indicate that maintaining tailings at or near saturation and/or excluding atmospheric oxygen produce leachates of nearly constant to slowly decreasing metal concentrations with each subsequent leaching.     

The interrelation of factors influencing the dissolution metals in columns of mine tailings

The dissolution of metal species from silver mine mill tailings containing quartz. (70%) and manganiferous siderite was investigated using a column leach procedure. The effects of leachant ionic strength, pH, and buffering ability were examined. The results indicated increased metal transport with increased ionic strength and decreased pH. In another test series, matched sets of columns were compared to determine the effect of leachate residence time on metal concentration. In these tests, leachate metal ion concentrations more than doubled in columns that were allowed to evaporate (wet/dry cycle) about 30% of their pore leachate volume. The pH of the leachate eluted from the dry cycle (unsaturated column) decreased while the conductance increased. Increases of five times were observed for lead and manganese, while increases of two orders of magnitude were seen for zinc and cadmium. The wet/dry cycle effect was enhanced during subsequent cycles, but appeared not to be influenced by the addition of sodium lauryl sulfate, sodium benzoate, or phenol, which are known to inhibit microorganism involvement. Increased sensitivity to further oxidation of those columns that underwent the dry cycle became apparent through increased deviation of the ion yields from duplicate columns. The interrelation of the above factors with the composition of the tailings present adds complexity to determining dissolution mechanisms.     

煤矸石对铜尾矿中重金属(Zn,Pb,Cd,Cr和Cu)形态及生物有效性的影响

铜尾砂堆积在地表会随着淋溶和风化作用溶出重金属元素,对环境产生一定危害,其生态修复的关键是进行基质改良,进行植物修复。通过黑麦草盆栽实验,将淮南煤矸石添加入铜尾砂,探讨矸石对铜尾砂中重金属行为的影响。结果表明:矸石添加能显著提高铜尾砂p H、有机质和养分水平(总氮、总磷和总钾),缓解尾矿砂贫瘠环境。矸石添加后,铜尾砂中Zn,Pb,Cd和Cu的交换态和碳酸盐结合态重金属逐步向铁锰结合态、有机结合态和残渣态转化(除个别处理Pb和Cu残渣态),铜尾砂中有效态Zn,Pb,Cd和Cu浓度不断降低,从而降低了黑麦草中相应重金属浓度,总体表现为铜尾砂-黑麦草系统内Zn,Pb,Cd和Cu生物活性降低效应。然而,由于矸石中Cr浓度相对铜尾砂偏高,其添加会引起尾矿砂中有效态Cr浓度及Cr迁移性增加而增大黑麦草对Cr的吸收。因此,煤矸石可对尾矿砂中Zn,Pb,Cd和Cu产生一定稳定化作用,而虽然矸石内源性Cr会释放到铜尾砂,其也可被黑麦草富集,由此,煤矸石可视为一种潜在的废弃物改良剂,对铜尾砂具有一定生态改良潜力。     

云南某矿山尾矿库分级尾砂用于矿山充填试验研究

为研究矿山尾矿库分级尾砂用于矿山充填,主要从尾矿库分级尾砂的物理化学性质、粒级组成进行了分析研究,进行分级尾砂的沉降性试验、坍落度试验和强度试验。试验结果表明,尾矿分级尾砂充填料浆的灰砂比1∶4～1∶8、料浆浓度68%～72%时料浆具有较好的流动特性、可泵性和充填体单轴抗压强度,论证了尾矿库分级尾砂可用于矿山充填,提升了矿山充填生产能力和固废物处置能力,有效解决了矿山采充平衡问题,可为同类矿山提供参考借鉴。     

西藏某矿厂铁尾矿中重金属形态及迁移潜力分析

以西藏某矿厂两个尾矿库的铁尾矿(TW-1，TW-2)为研究对象，采用《浸出毒性浸出方法 硫酸硝酸法》HJ/T299-2007研究铁尾矿的浸出毒性，以改进的BCR法探讨铁尾矿中9种重金属的形态分布。结果表明：铁尾矿属于一般固体废弃物，铁尾矿中Fe、Mn 、Zn和Cu含量较高。铁尾矿中As含量超出一类用地风险筛选值3倍。TW-1中Cd的浸出浓度超出Ⅱ类水标准。TW-1重金属活性系数的大小为Pb>Cd>Ni>Zn>Cu>Mn>Cr>Fe>As，TW-2重金属活性系数的大小为Pb>Zn>Ni>Cd>Mn>Cu>Cr>Fe>As。综合9种重金属的迁移能力，结果为TW-1重金属迁移潜力大于TW-2。铁尾矿中的Pb、Cu、Cd和Zn的易于迁出态占比超过60%，对环境有潜在的风险。其中Pb以还原态为主，Cu、Cd和Zn以氧化态为主。     

大屯锡矿尾砂膏体环管管输数值模拟研究

膏体管输沿程阻力是影响管道设计与采场充填质量的关键因素之一,本文采用fluent建立与实际环管实验系统一样的管道输送的几何模型,分析得到不同管线沿程阻力损失之间的关系以及膏体配比参数对沿程阻力损失的影响规律。 研究表明：膏体在管道中弯管处的速度和压力都发生急剧的变化,弯管外侧压力和速度明显大于弯管内侧,有着明显的梯度。在水平管段速度和压力在管道径向上存在明显的梯度,呈结构流的特点,分为柱塞流动区和边界层区域。在膏体管道输送中管道内膏体的速度和压力均存在着边界效应,随着流速的增大管输阻力增大;随着膏体质量浓度增加,沿程管道阻力损失变大;随着屈服应力与塑性粘度的增加沿程阻力损失也增大,获得了不同物料组成、管道内径、管流流速下水平段膏体压力损失,为大屯锡矿最终输送泵、充填管道选型提供了依据。     

甘肃某铅锌矿尾砂胶结充填试验研究

甘肃某铅锌矿建矿已有30多年,矿山现有尾矿库即将达到服务年限,矿山在不建新尾矿库的情况下,为新产生的尾砂寻找经济合理、安全环保的处置方式。经过多年开采,井下已存在大量采空区,矿山拟采用全尾砂充填采空区的方式解决尾砂堆存问题,同时对采空区进行治理。在保证尾砂输送至采空区后能正常胶结的前提下,寻求最经济的灰砂比,本文分别以水泥和新型胶结材料作为胶凝材料进行试验,确定最优的尾砂浓度、灰砂比和胶凝材料。通过试验,在满足充填体正常胶结的情况下,选用新型胶结材料作为胶凝材料所需要的灰砂比更小,充填成本更低,从而为矿山提供更经济、安全的充填方案,为矿山解决尾矿处置找到了更经济、安全环保的方式。     

嗜酸性氧化亚铁硫杆菌对钼镍尾矿中金属浸出行为影响的研究

利用氧化亚铁硫杆菌（At.f菌）对钼镍尾矿进行生物浸出试验,探究初始Fe2+浓度、pH值、钼镍尾矿矿浆浓度对钼镍尾矿中Ni、Zn、Mo、Cu浸出率的影响。对比研究At.f菌的生物浸出和Fe3+及稀硫酸的化学浸出过程的差异。结果表明：At.f菌浸出体系初始Fe2+的质量浓度在9~12 g/L时,At. f细菌浸矿最佳;pH值在1.0~2.6时,pH值对At. f细菌浸出浸矿体系的整体影响不大;矿浆浓度越低,对金属矿的浸出效果越好。At.f菌的生物浸出对尾矿中Ni、Zn浸出效果明显好于Fe3+及稀硫酸的纯化学浸出,浸出16 d后,Ni和Zn最大浸出率分别为66.93%和82.71%。而Fe3+的化学浸出体系对Mo的浸出效果优于At.f菌和稀硫酸浸出体系。At.f菌、Fe3+及稀硫酸浸出第16 d时,Cu浸出率分别为85.46%、61.52%和92.35%。At.f菌在浸出体系中不断产生的Fe3+和H+对尾矿可进行持续氧化作用,后期主要是以At. f菌的直接氧化为主。XRD结果显示,在At. f的浸矿过程中,存在着大量的铵黄铁矾,钝化尾矿金属的浸出。量的铵黄铁矾,钝化尾矿金属的浸出。     

金川矿山废石与酸浸尾砂最优配合比的研究

为了找出金川矿山废石与酸浸尾砂的最优配合比,即二者混合后达到最大堆积密实度,应用两种骨料堆积密实度模型计算出理论最大值,同时使用试验测量的方法得到了最优组,最终结合两种结果得到:废石∶酸浸尾砂应控制在7∶3与8∶2之间为最优范围。这为矿山后续强度的要求与管道输送提供了保证,同时可为同类矿山的设计提供参考。     

Mineral carbonation of PGM mine tailings for CO2 storage in South Africa: A case study

The ultra-fine milled tailings generated during the processing of PGM ores in South Africa have a theoretical potential to sequester significant amounts of CO₂ (∼14 Mt per annum) through mineral carbonation. Mg-bearing orthopyroxene is the major sequestrable mineral in these tailings, which also contains significant quantities of Ca-bearing plagioclase, as well as minor quantities of clinopyroxene, olivine, serpentine and hornblende. In this study, the feasibility of using PGM tailings to sequester CO₂ has been investigated empirically using the two-step, pH swing method. The rates and extents of cation (Ca, Mg and Fe) extraction and subsequent carbonation were determined and compared. Both organic (oxalic and EDTA) and HCl solutions were utilised in the cation extraction step, which was conducted at time periods up to 8 h and at a temperature of 70 °C. The extents of cation dissolution were relatively low under all experimental conditions investigated, particularly for the case of Mg (between 3.3% and 5.0% extraction). A comparison of the extents of leaching with the mineralogical composition of the tailings indicated that the extracted Mg originated primarily from clinopyroxene, with the orthopyroxene remaining relatively inert under the experimental conditions. Subsequent carbonation of the acid leach solution after pH adjustment with NaOH resulted in the rapid formation of a number of carbonate minerals, including gaylussite (Na₂Ca(CO₃)₂·5(H₂O)), magnesite (MgCO₃), hydromagnesite (Mg₅(CO₃)₄(OH)₂·4H₂O), dolomite (CaMg(CO₃)₂), ankerite (Ca(Fe,Mg)(CO₃)₂), and siderite (FeCO₃). On the basis of these findings, further studies will be focused on developing a better understanding of the factors affecting the dissolution of Mg-bearing orthopyroxene minerals, and on exploring alternative leach reagents and conditions, with a view to developing a more effective process for the accelerated carbonation of PGM tailings.     

Formulating and optimising the compressive strength of controlled low-strength materials containing mine tailings by mixture design and response surface methods

Controlled low-strength materials (CLSM), like other cement-based backfill materials, are typically formulated by trial-and-error methods to yield the desired product characteristics. This paper presents the use of mixture design and response surface methods as tools to optimise formulations of CLSM to achieve desirable mechanical integrity with a minimum amount of statistically-sound experiments; while minimising the amount of cement and maximising the amount of by-products used. Statistical combinations of three-component mixtures were formulated to investigate the unconfined compressive strength (UCS) of CLSM comprising: Portland cement, fly ash and mine flotation tailings from a Ni–Cu ore. The data is analysed using the response surface method (using a mixture design of a constrained triangular surface) and ANOVA. Optimum formulations are simulated using a desirability function set at lower (1.0 MPa), target (2.0 MPa) and upper (3.0 MPa) UCS values after 28 days curing. All mix combinations had a constant spread diameter of 229 ± 10 mm, the standard workability for conventional CLSM. Results are compared to conventional CLSM incorporating silica sand in the place of the tailings. A significant quantity of tailings (up to 80 wt% solids) and low quantity of cement (up to 5 wt% solids) produced CLSM with UCS within the 2 MPa target value of excavatability. UCS of CLSM is a function of the individual component proportions, and the mixture design approach can be an important tool to help develop and optimise formulations of cement-based materials consisting of several components.     

戈壁砂和全尾砂充填骨料在金川矿山的应用研究

充填骨料是充填材料的重要组成部分,充填骨料的选择与应用直接影响充填采矿成本和采矿经济效益。戈壁砂和全尾砂在金川充填采矿中的应用,是降低金川充填采矿成本的重要途径之一。根据金川矿山充填系统和工艺参数,采用高浓度料浆和1∶4高灰砂比,开展了戈壁砂、全尾砂和棒磨砂的混合料配比试验。试验结果表明,作为充填骨料戈壁砂与棒磨砂不存在本质上差异,可以替代棒磨砂用于金川矿山充填法采矿。全尾砂与棒磨砂混合充填骨料的胶结充填体强度试验发现,当全尾砂掺量控制在30%以内,3 d充填体强度高于纯棒磨砂充填骨料,同时7 d和28 d充填体强度达到金川矿山充填体设计强度。该研究成果应用于金川矿山充填采矿生产,为戈壁砂和全尾砂的工业化应用奠定了基础。     

浅谈城郊矿井井口位置选择与储量中心的关系

在矿井设计中，井口位置的选择是至关重要的，井口位置选择正确、合理，直接影响到矿井建设的投资、工期以及经济效益。该文章通过城郊矿井井口位置的选择，论述了井口位置与储量中心的关系及井上下运输对井口位置选择的影响。     

广西珊瑚氧化物型尾矿重金属污染综合评价

对广西珊瑚尾矿样中重金属As、Cd、Cu、Pb、Zn的含量进行了分析测试,以国家土壤质量Ⅲ级标准作为参比值,利用地累积指数法、综合污染评价法和潜在生态危害指数法对珊瑚尾矿的污染状况进行了综合评价。地累积指数法和综合污染法评价结果显示,珊瑚尾矿研究区Cd、As污染较为严重,较国家土壤质量Ⅲ级标准值超标倍数均值>40倍,Zn和Cu元素为轻微污染,Pb无污染,重金属污染程度相对大小为：Cd>As>Zn>Cu>Pb;潜在生态危害指数法评价结果显示,重金属污染程度相对大小为：Cd>As>Cu >Zn >Pb。综合上述三种评价方法表明,珊瑚尾矿中：Cd和As对综合污染指数的贡献最高,说明珊瑚钨矿区Cd和As为主要污染因子。     

柴北缘锡铁山矿区尾矿铅锌分布特征及污染防治探讨

锡铁山铅锌矿床是柴北缘铅锌成矿带最典型的大型铅锌矿床之一,位于青藏高原东北部。锡铁山已有多年的开发历史,矿业活动所产生的固废物会携带高浓度的污染元素,而尾矿库是污染元素的重要聚集场所。通过野外调查,样品采集、测试分析等,分析尾矿库矿物组合及铅锌元素赋存状态,旨在揭示高原地表环境下铅锌重金属迁移、赋存形态及累积过程,阐明重金属铅锌元素迁移机制。通过在沉积物中剖面分层采样,对样品矿物组合及铅锌含量进行分析,总结铅锌含量分布变化规律。研究结果表明,尾矿中矿石矿物主要为闪锌矿、方铅矿及黄铁矿,脉石矿物主要有石英、方解石、角闪石及透辉石。尾矿库中重金属铅锌含量均高于背景值,铅元素迁移能力中等,锌元素迁移能力相对较强,该研究认识有利于绿色矿山建设,有利于生态效应理论积累新知识。     

尾砂级配对充填体强度的影响及优化

尾砂级配是影响充填体力学性质的重要参数,研究级配对充填体强度的影响具有重大现实意义。以A、B和C三种全尾砂为试验材料,通过激光粒度分析仪测得三种全尾砂粒径级配组成,结合全尾砂充填体强度,得到级配与充填体强度之间的关系:C全尾砂级配优于B,A全尾砂级配较差;级配越好,充填体强度越高。借助XRD能谱分析和SEM电镜分析可得,A试块和C试块由于级配不同,导致水化反应初期(3d)A试块钙矾石(针状)明显少于后者,28d报告时C试块团絮状胶凝物黏结更紧密,从而影响了试块的充填体强度,使得级配较优的C试块充填体强度明显高于A试块。通过优化级配的方法对级配较差的全尾砂A进行优化分级,提高了充填体强度。     

某云母矿中稀有金属赋存状态分析及云母选矿工艺研究

某云母矿含锂、铷、钽、铌等多种稀散金属,矿物成分以长石、石英、云母为主,锂、铷元素主要分布于云母矿物中,少量分布于钾长石,铌、钽元素以类质同向形式赋存于铌铁钽锰矿.矿石中云母矿物包括铁锂云母和锂白云母,呈浸染状分布,粒度较粗,探索实验研究表明重选难以有效回收.本研究确定采用浮选回收工艺,在矿石性质研究基础上,采用二次磨矿-二次脱泥-五次精选二次扫选工艺流程回收矿石中的云母矿物,可获得LiO2、Rb2O品位3.04％、0.91％的云母精矿,LiO2回收率77.80％,LiO2、Rb2O合量回收率74.26％.该研究结果可作为开发利用该类含锂、铷云母矿回收利用的基础技术依据.     

矿山废石全尾砂充填研究现状与发展趋势

矿产资源开发过程中产生的废石、尾砂和冶炼渣,等占我国工业固体废料排放量的85％左右.大量矿山固体废料堆放地表,易造成严重污染,诱发泥石流、尾矿溃坝事故.固体废料充填工艺是解决矿山废尾排放的最有效途径.本文介绍了低浓度分级尾砂充填、全尾砂高浓度充填、膏体似膏体充填、块石胶结充填工艺的研究与应用现状,并分析了矿山废石全尾砂充填技术的研究与发展方向.