Hydrochemical models of the sulphidic tailings dumps at Matchless (Namibia) and Selebi-Phikwe (Botswana)

The sulphidic tailings dumps at Matchless (Namibia) and Selebi-Phikwe (Botswana) are located in a similar semiarid environment but have a contrasting mineralogical composition. The Matchless tailings are pyrite-rich, whereas the Selebi-Phikwe tailings are dominated by pyrrhotite. Hydrochemical models are established with computer codes for water-balance, sulphide oxidation rate and hydrochemical equilibrium calculations. The data input is based on detailed mineralogical, chemical and kinetic investigations carried out on the core of boreholes drilled in 2000 and 2003. The oxidation of pyrrhotite proceeds at a much faster rate than the oxidation of pyrite. The PYROX code, which is used for kinetic calculations, can take these differences into account by applying different oxide-coating diffusion coefficients (D₂) for pyrrhotite and pyrite. Humidity-cell testing is widely used to predict the post-mining composition of drainage water in humid climates. However, the semiarid conditions at Matchless and Selebi-Phikwe only allow a minimal water flux within the dump. Under such conditions, humidity-cell testing is likely to overestimate the seepage-water pH. This is suggested by the hydrochemical equilibrium calculations for the post-mining period at Selebi-Phikwe, which predict a seepage-water pH about one unit lower than the pH at the end of the 26-weeks humidity-cell testing period. The acidity of the seepage water can be reduced by about half a pH unit, if an oxygen barrier below the evaporation zone is installed. A clay layer 0.5 m thick covered by >1.5 m tailings represents the optimal design for a wet barrier. All three computer codes used for water-balance calculations (HELP3, UNSAT-H and HYDRUS-1D), predict >85% average water saturation for such a layer, which diminishes the diffusion of oxygen into the pile and production of SO₄⁻² and H⁺. The alternative design for a dry barrier consists of a vegetated silt layer 1 m thick on top of the tailings. This barrier does not significantly influence the diffusion of oxygen although it reduces the net infiltration to ≤11 mm/year.     

21世纪的新型资源--尾矿资源的开发

本文介绍了尾矿及其在国内外和江西开发利用的现状;分析了存在的问题;对江西尾矿资源开发利用提出了若干意见。     

复杂地形尾矿坝的三维渗流分析

对于复杂地形的尾矿坝,由于二维模型不能充分反映复杂多变的渗流域,也不能考虑到三个方向渗流因素同时作用的影响,从而无法体现真正的渗流场。通过建立三维渗流数学模型,并考虑复杂断面概化和地形的简化,对实际工程进行了数值计算,其结果与试验结果吻合较好。结果表明,对复杂地形的尾矿坝渗流分析时必须采用三维模型,三维数值计算中对复杂地形进行适当的简化和概化对结果的影响较小,可以满足精度要求,因此大大减小了计算的复杂程度和难度。     

江西××胶磷矿选矿试验研究

针对江西× ×难选胶磷矿,采用单一正浮选工艺进行试验.试验对各主要影响因素逐一研究分析,获得了最佳药剂制度,并在此基础上有针对性的进行了三组闭路试验,均获得了较满意的选别指标,满足了选矿厂的不同需求.研究结果为该胶磷矿的开发利用提供了技术支持.     

Subsurface grout barriers for ground stabilization in dolomite areas near Carletonville, South Africa

 Artificial lowering of the groundwater level in dolomitic aquifers of the Far West Rand gold mining area has led to the formation of hundreds of sinkholes and subsidences. Where ground movements develop in or around important structures, it has become standard practice to drill boreholes for exploration and to inject mine tailings (slimes), cement and water to fill cavernous zones and arrest further ground movements. Although this method of grouting has mostly been effective, some boreholes accepted such large quantities of grout that the operation became prohibitively expensive. This paper describes an experiment to construct subsurface barriers by pouring wet (high slump) concrete via closely-spaced lines of boreholes into cavernous zones beneath a depression on a provincial road. The barriers required a small quantity of concrete and the zone between barriers was quickly filled by grout. The lack of further ground movements confirmed the success of the project. Received: 22 May 2000 · Accepted: 18 July 2000     

大型高尾矿坝灾变机制与防控方法

大型高尾矿库隐患治理是"十三五"期间遏制重特大事故的重要任务和重点工程之一。高应力下尾矿材料的细观结构和宏观力学特性演化、大型尾矿坝沉积规律及复杂条件下高尾矿坝的劣化理论是其中的关键问题。为揭示尾矿细观结构特性,对尾矿材料进行了光学显微镜观察、电镜扫描和CT扫描处理,建立了尾矿材料的三维重构模型;为揭示高压下尾矿材料的力学特性,对尾矿进行了高应力三轴试验、高应力渗透固结联合试验,研究了高应力下尾矿材料的强度、渗透和固结特性;为揭示尾矿的沉积特性,进行了尾矿材料的大型模型试验,得到了矿浆流动、淤积形态、尾矿料物理力学性质的空间分布以及夹层结构在空间内的分布规律;为揭示高尾矿坝的失稳机制,通过理论分析与数值模拟,对高压下尾矿的强度准则进行了讨论,高尾矿坝的稳定性分析建议使用强度折减法;为揭示尾矿的排渗设施淤堵机制与服役性能,进行了尾矿-土工布渗透试验以及微观观测,发现细粒尾矿更容易产生物理淤堵,且化学淤堵程度与溶液中离子的种类和浓度有关;为了推进尾矿坝风险管控技术,搭建了尾矿库重大风险评估监测系统平台,以便实现尾矿库基础数据的提取、实时风险预警等智能化功能。通过以上坝体劣化理论研究、溃坝灾害评估与预警,提升了我国大型高尾矿库筑坝与灾害防控水平。     

基于流固耦合作用的某尾矿坝渗流稳定性分析

尾矿坝是矿山重要设施之一,其内部含有大量的水和尾矿,一旦失稳造成的损失不可估量。尾矿坝失稳有众多因素影响,但是坝内浸润线是最活跃的影响因素。本文基于流固耦合理论,建立某尾矿坝有限元计算模型,考虑坝内排水井的存在。模拟坝内不同工况下浸润线分布,对其静力稳定性及流固耦合作用下尾矿坝应力应变场进行分析,并将浸润线模拟位置与实际监测结果进行对比。揭示库内不同工况下浸润线变化规律以及与坝体稳定性之间的关系,并分析评价不同工况下尾矿坝的稳定性。最后,将渗流场与应力场进行流固耦合,模拟出365 d坝内应力位移分布,为尾矿坝施工及安全运行提供可靠的依据及技术支持。     

湖南省××磷矿选矿工艺研究

针对湖南省××磷矿矿石性质及可选特性,采用擦洗脱泥—浮选联合工艺选别,有效降低了能耗和药耗,使P2O5品位由15.78%富集至30.77%,P2O5回收率为82.40%,磷精粉达到酸法加工用磷矿石一等品Ⅰ级标准。     

大厂矿区尾矿稀散资源分布规律与潜力评价研究

许多矿山开采和选矿排放的尾砂中蕴藏丰富的伴生金属资源,随着这类矿产资源价格上涨,尾砂伴生资源越来越受到人们的关注。本文对大厂矿集区茶山、车河、长坡和绿荫塘四个尾矿库中铟、镉、镓、锗等稀散元素分布特征与变化规律进行了调查,以期评价其潜在经济价值。调查结果表明,解放前修建的绿荫塘老尾矿库尾砂稀散元素铟、镉、锗均远超过工业品位,具有一定开采价值。70年代修建的长坡尾矿库铟、镉达到工业品位;90年代修建的车河、茶山尾砂库只有铟达到工业品位。四个尾矿库中稀散元素含量与尾砂来源和选矿水平密切相关,并发生次生淋滤富集作用。对环境有毒害的稀散元素镉尽管含量较高,但其主要赋存在闪锌矿中并没有释放到土壤环境中产生污染。这些调查研究结果将为政府部门和矿山企业决策提供依据。