Assessment and prediction of contaminant migration in ground water from chromite waste dump

Sukinda chromite valley is one of the largest chromite deposits of the country and produces nearly 8% of chromite ore. It greatly contributes towards the economic development but at the same time deteriorates the natural environment. It is generally excavated by opencast mining method. In the Sukinda mining area, around 7.6 million tons of solid waste have been generated in the form of rejected minerals, overburden material/waste rock and sub-grade ore that may be resulting in environmental degradation, mainly causing lowering in the water table vis-à-vis deterioration in surface and ground water quality. The study conducted in and around one of the chromite mine of the valley reveals that the concentration of hexavalent chromium is found in the water samples of ground and surface water, mine effluents and seepage water. Hexavalent Chromium (Cr⁺⁶) have been found varying between 0.02 mg/l and 0.12 mg/l in mine effluents and 0.03–0.8 mg/l in shallow hand pumps and 0.05 and 1.22 mg/l in quarry seepage. The concentration of Cr⁺⁶ in Damsal nalah, the main surface water source in the area, is found varying between 0.03 mg/l and 0.14 mg/l and a increasing trend, which is in the downstream of mining activities, has been observed. Leachate study clearly shows that the soil lying in the vicinity of mine waste dump shows highest concentration of Cr⁺⁶. Contaminant migration in ground water depends upon various geohydrological conditions of the area. The study shows that aquifer resistivity varies between 15 Ωm to 150 Ωm and aquifer depth varies from 4 m to 26 m below ground level. The ground water flow and mass transport models were constructed with the help of geo-hydrological and geophysical informations using Visual Modflow software. Contaminant migration and path lines for 20 years have been predicted in two layers model of ground water. The study provided an insight into the likely migration of contaminant in ground water due to leaching from overburden dump of chromite ore and will be helpful in making strategic planning for limiting the contaminant migration in the ground water regime in and around the mining areas.     

Temporal variation in discharge chemistry and portal flow from the 8-Level adit, Lynx Mine, Myra Falls Operations, Vancouver Island, British Columbia

The Lynx mine, currently inactive, has produced copper and zinc concentrates from massive sulfide deposits on a lease within the rainy, mountainous interior of Vancouver Island. Tailings, used to back-fill a mined-out stope, are being leached by percolating groundwater and the resulting acidic, metal-laden drainage is discharging from the portal of the 8-Level adit. Temporal variations in the flow rate, specific conductance and temperature of the discharge were monitored continuously over a 2-year period while effluent chemistry was sampled weekly. Conductivity was relatively constant throughout most of the year but peaked with the first autumn storm events as accumulated soluble sulfide oxidation products were flushed from the workings. Concentrations of sulfate and most metals were closely correlated with conductivity as were low pH values as stored acidity was released along with dissolved species. Variations in pH controlled the speciation and partitioning of metals between dissolved and particulate phases.     

在我国发现的Schwertmannite矿物及其特征

采用X射线衍射(XRD)、扫描电镜与能谱(SEM-EDX)、X射线荧光(XRF)、傅立叶红外光谱(FT-IR)、热分析(DTA-TG)等分析方法,在我国山西马兰煤矿的酸性矿坑排水(AMD)沉淀物中首次发现了“斯沃特曼铁矿”(Schwertmannite)。研究表明,山西马兰煤矿酸性矿坑排水沉淀物中的Schwertmannite矿物的粒径为0.3~70μm,且分布比较均匀,其BET表面积为44.065 0 m2/g;SEM二次电子像显示为球形或椭圆形(聚集体)结构,颗粒大小比较均匀,球的表面有针状毛刺;该矿物的化学式为Fe8O8(OH)4.52(SO4)1.74.4.73H2O。     

四川丹巴白云母矿山公园矿业遗迹资源特征及评价

四川丹巴白云母矿是我国开发最早的白云母矿之一。在悠久的开采历史中遗存下了十分丰富的矿业遗迹,成为该公园建设的基础。这些遗迹典型、稀有,系统完整,科学价值高,组合独特,具有很高的历史文化价值。此外,公园内配套的自然人文景观丰富,旅游区位条件良好,矿业遗迹开发价值巨大。     

贯通式潜孔锤新技术在矿山勘探中的应用试验

针对栾川钼矿复杂地层勘探遇到的技术难题,采用贯通式潜孔锤全孔反循环钻进工艺方法,对钻进中遇到的开孔难、漏失严重、活塞断裂等技术问题,进行了工艺研究、设计方案改进。试验表明,该技术方法具有岩芯(样)采取率高、钻进速度快的特点。     

湖南省界牌岭矿区水文地质条件的认识

文章论述了界牌岭矿区水文地质条件,并且根据原有资料对矿山开采中暴露的地质环境问题进行综合分析,取得了对矿区水文地质条件较全面的认识。     

典型煤矿区环境地质灾害及其防治

结合煤矿生产过程中所引起的采矿塌陷、水体污染、煤矸石污染、水土流失、空气污染等环境地质问题,对大中型煤矿环境地质灾害的类型和发生原因进行分析,并提出防治对策。     

Environmental investigation for causality and remediation of cadmium contaminated soils in Tak Province, Thailand

Highly elevated cadmium concentrations in paddy soil in the Mae Sod District, Tak Province, Thailand, was detected and widely reported in 2003. This emergence provoked public interest and demands for responsibility and remedial actions. As zinc mines and concentrator were located in the upstream area, mining activities were proclaimed a contamination source. Department of Primary Industries and Mines （DPIM）, a governmental organization responsible for mining and mineral processing, was thus challenged to verify the reliability of post monitoring data displaying consistently low heavy metal concentrations in compliance with the standard limits for over 15 years. Detailed survey and deep-going research on the causes, boundary and severity of cadmium contamination as well as the environmental impact alleviation were consequently conducted. Environmental samples were accumulated systematically for 2 years throughout the areas of upstream and downstream mining sites. A total of 259 soil samples from 53 spots at the depths of 0-20, 20-40, 40-60 and 60-200 cm were drilled with hand auger. Samples of water, stream sediment and mine tailing were also collected. Chemical analysis for cadmium （Cd）, zinc （Zn） and lead （Pb） concentrations with AAS and ICP were undertaken. The contaminated area was finally defined to spread over approximately 18 square kilometer mainly of mountainous mineralizing land and colluvium.     

The Development of a new Numerical Modelling Approach for Naturally Fractured Rock Masses

Summary. An approach for modelling fractured rock masses has been developed which has two main objectives: to maximise the quality of representation of the geometry of existing rock jointing and to use this within a loading model which takes full account of this style of jointing. Initially the work has been applied to the modelling of mine pillars and data from the Middleton Mine in the UK has been used as a case example. However, the general approach is applicable to all aspects of rock mass behaviour including the stress conditions found in hangingwalls, tunnels, block caving, and slopes. The rock mass fracture representation was based on a combination of explicit mapping of rock faces and the synthesis of this data into a three-dimensional model, based on the use of the FracMan computer model suite. Two-dimensional cross sections from this model were imported into the finite element computer model, ELFEN, for loading simulation. The ELFEN constitutive model for fracture simulation includes the Rotating Crack, and Rankine material models, in which fracturing is controlled by tensile strength and fracture energy parameters. For tension/compression stress states, the model is complemented with a capped Mohr-Coulomb criterion in which the softening response is coupled to the tensile model. Fracturing due to dilation is accommodated by introducing an explicit coupling between the inelastic strain accrued by the Mohr-Coulomb yield surface and the anisotropic degradation of the mutually orthogonal tensile yield surfaces of the rotating crack model. Pillars have been simulated with widths of 2.8, 7 and 14 m and a height of 7 m (the Middleton Mine pillars are typically 14 m wide and 7 m high). The evolution of the pillar failure under progressive loading through fracture extension and creation of new fractures is presented, and pillar capacities and stiffnesses are compared with empirical models. The agreement between the models is promising and the new model provides useful insights into the influence of pre-existing fractures. Further work is needed to consider the effects of three-dimensional loading and other boundary condition problems.     

Investigation of lead and zinc dispersion from an abandoned mine site at Tyndrum, Scotland, using tree bark measurements

Tyndrum was an industrial mining area from 1741 until the 1920s where the main ores extracted were lead sulphide （galena） and zinc sulphide （sphalarite）. Situated in central Scotland, the now deserted site is identified as a highly polluted, barren area where the original waste residues from the mine, an ore processing and a smelting site are clearly evident. Previous studies have suggested that high levels of lead and zinc contaminants are still dispersed from this former mine site, both atmospherically and through fluvial transport. For example, high concentrations of Pb, identified by its isotopic signature as originating in Tyndrum, have been found in sediments in Loch Tay, 25 km east of this area. This paper presents the results of a study of the occurrence and magnitude of airborne contamination by dispersion from the former mine site using measurements of metal concentrations in tree bark. These naturally occurring ‘bio monitors＇, which accumulate airborne materials including heavy metals, have become an effective alternative to the more costly air-filter system, which is restricted in scope and coverage. Bark samples were acquired from Scots pine （Pinus sylvestris） trees, which are abundant around the derelict mine site. Suitable locations were chosen to investigate atmospheric transport and deposition of contaminants within the area.