The aging of gypsum in underground mines

The aging properties of gypsum extracted from two underground mines in France (Livry–Gargan and Grozon) have been highlighted by means of observation performed using scanning electron microscopy on samples taken along horizontal boreholes drilled through to the middle of several pillars. The aging process is exhibited by the presence of traces of dissolution (edges of the dissolved crystals, corroded crystalline surfaces, important intra- and intercrystalline space). These dissolution figures decrease in number and in intensity from the wall heading towards the middle of the pillar. The “older” pillars display a greater number of dissolution traces than the “more recent” pillars. Then, the role of the aging has been assessed by determining various physical and mechanical parameters on cylindrical samples of 38 mm in diameter and 76 mm in height, machined from the set of drilled boreholes. The following parameters have been quantified: density, grains density, total porosity, porosity accessible to water, intrinsic permeability to nitrogen, velocity of ultrasonic compression and shear waves, dynamic Young's modulus, dynamic Poisson's ratio, uniaxial compressive strength and static Young's modulus. Significant variations in parameter values between the wall and the middle of the pillar were recorded and recognized as being strongly correlated with the intensity of dissolution traces, and hence with gypsum aging.     

Uranium pollution of South African streams – An overview of the situation in gold mining areas of the Witwatersrand

During more than a century of gold mining in South Africa large amounts of tailings were produced, which now cover vast areas in densely populated regions. These dumps contain elevated levels of uranium and other toxic heavy metals associated with gold in the mined ore. Large-scale extraction of uranium from auriferous ore only took place during the cold war, leaving tailings with high uranium concentrations that were deposited before and after this period. Recent studies found elevated levels of the radioactive heavy metal in groundwater and streams, mainly attributed to the discharge of contaminated water from mines. In this paper the contribution of seepage from slimes dams to the uranium pollution of adjacent streams is analysed. Based on geochemical analyses of samples, field observations and long-term in situ measurements of hydraulic and hydrochemical parameters at selected mining sites across the Witwatersrand goldfields, the extent, mechanisms and dynamics of diffuse stream contamination by tailings seepage is characterised. Temporal and spatial variations of the process and the associated hazard potential are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

A simple accelerated rock weathering method to predict acid generation kinetics

The development of effective, and economical pre-development waste rock management plans requires an accurate estimate of the quality of drainage generated during mining. This study was conducted to determine if a simple accelerated rock weathering method with lower capital and personnel costs can be used in lieu of the elaborate and costly ASTM method to predict the quality of drainage generated. It involves subjecting rock samples to a constant relative humidity and temperature for 7 days and leach flooding the weathered samples on the 7th day. The acid production rate from the new weathering method correlates quite well with the net neutralization potential generated from the standard acid-base accounting procedure (R²=0.940) which has been demonstrated to be correct 90% of the time in assessing overburden quality, and a mineralogical method (R²=0.924). For investigators interested in generating weathering kinetic parameters, the simple and less costly accelerated weathering method is proposed.     

原子荧光光谱法直接测定铜矿中的硒

采用硫脲抑制铜的干扰，不经分离富集原子荧光光谱法直接测定铜矿中的Se。方法的检出限为0．02μg/g。Se浓度在0～80μg／L与荧光强度呈线性关系。用铜矿石国家一级标准物质GBW 07233(ωSe为5．1μg／g)和GBW 07234(ωSe为0.89μg／g)进行精密度试验，RSD(n=12)为3.44％、8.06％。加标准回收试验结果，Se的回收率为93．2％～104、6％。经铜矿石国家标准物质验证，测定结果与标准值相符，方法适用于铜矿中0～8．0μg／g Se的测定。     

伸展型脆-韧性剪切带对沃溪钨锑金矿床的构造控制

湖西沃溪钨锑金矿床受控于一条伸展型顺层脆-韧性剪切带。带内岩石在非共轴顺层剪切构造动力作用下发生变形分解，形成泥质构造根岩强变形带和砂质构造根岩弱变形域。泵吸中心-弱变形城中的承压矿液沿砂质构造根岩的ab面发生水力压裂而产生“D”型张剪裂隙。构造-流体双重动力系统的周期性振荡使主裂隙系统发生周期性的破裂-愈合作用而形成条带状复脉。矿液是通过隐蔽的低角度正断层、强变形带内的构造面理及弱变形城中的微裂隙系统运移的，说明在靠近滑脱面的弱变形城中水力压裂作用会增强，其矿化类型将以蚀变岩型为主、脉型为辅。     

攀枝花地区主要露天矿山地质环境特征及评价

随着矿业的发展，越来越多矿山的地质环境问题已成为人们关注的对象，如何预防、治理矿山地质灾害，对攀枝花这样的矿业城市意义重大。攀枝花大型露天矿山地质环境复杂，随着矿山向深度开采，已产生了滑坡、崩塌、泥石流等诸多环境地质问题，对生产和周边环境造成了不良影响，正成为政府、社会、矿山共同关注的问题。     

小浪底水库蓄水运行对矿井水害防治的影响评价

新安煤矿系我国大水矿区,地下水害严重威胁着矿井的安全生产。本文根据大量原始资料,运用灰色系统理论和风险分析理论,讨论了小浪底水库蓄水运行对新安煤矿水害防治所造成的影响,明确指出水库蓄水后矿井突水威胁主要来自断层水及石炭系太原群L7～8岩溶水;煤矿防治水的重点应该是治理L7～8灰岩及矿区边界断层在库区的露头或隐伏露头。     

四方山矿采区地表变形及对地面建筑的影响

偏远山区矿山开采多以小窑掘进为主，其对地表变形的影响已引起人们的重视。根据四方山煤矿所处的地质环境及开采的实际特征，通过对其采深采厚比和顶板岩层质量的分析，采矿厚度、采空段宽度的计算，得出该区小窑开采对地表变形无影响的结论。     

山东西南部南四湖流域环境地质综合调查

本文论述了水体污染、矿山环境地质灾害、地下水环境异常、南四湖淤积、地球化学环境与地方病等环境地质问题，探讨了煤炭开采对南四湖湖容演变的积极影响。湖体及主要人湖河流污染严重；流域内煤炭资源开发引起的矿山环境地质灾害比较严重，地面塌陷面积达112．395km^2；各种固体废弃物积存总量6412．68万t；矿井排水对矿区地下水资源造成严重破坏。地方病以地氟病和克山病为主。在对流域内环境地质问题综合分析的基础上，提出了对流域环境地质问题的治理措施。     

齐波夫分布律与阻尼曲线在夹皮沟金矿田成矿预测中的应用

用齐波分布律和阻尼曲线现象进行矿产资源预测，具有采用数据少，计算方法简单的特点，与元素丰度模型法，黎彤法等方法预测的结果基本相当，夹皮沟金矿田是一研究程度与开采程度都很高的地区，运用齐波夫分布律和阻尼曲线现象对其进行预测，夹皮沟金矿田仍有500t左右的潜在资源量，找矿潜力达74％，尤其是沿主剪切带附近，仍有大型，超大型矿床隐伏，只是勘探深度要大大增加。