Ground Water Control Techniques for Safe Exploitation of the Neyveli Lignite Deposit, Cuddalore District, Tamil Nadu, India

Dewatering in deep opencast mines generally focuses on extraction of seepage water from the phreatic zones above the ore/mineral deposits and storm water that collects in mine pits. But at the Neyveli lignite deposit in the Cuddalore District, there was a danger of the mine floor bursting due to the hydrostatic head pressures in the underlying thick confined aquifers, a problem not previously encountered anywhere in India. Hydrogeological studies established the feasibility of mining the lignite by maintaining a constant cone of depression (pressure relief) in the surrounding aquifers below the mine by continuous pumping through a pre-planned network of wells. This depressurizing process had to be designed to tackle multi-layered confined aquifers and water table conditions. This paper traces the multi-faceted evolution in developments to control ground water at the Neyveli Mines.     

Assessment of Hydrogeochemical Processes and Mine Water Suitability for Domestic,Irrigation, and Industrial Purposes in East Bokaro Coalfield,India

Mine water samples collected from the East Bokaro coalfield were analysed to assess suitability for domestic, irrigation, and industrial purposes. The pH of the samples ranged from 6.78 to 8.11 in the pre-monsoon season, 5.89–8.51 during the monsoon season, and 6.95–8.48 in the post-monsoon season. The anion chemistry was dominated by HCO₃^? and SO₄^2?, with minor amounts of Cl^?, NO₃^? and F^?. The Fe concentrations exceeded the maximum permissible limit of the BIS drinking water standard in about 44% of the collected samples. Turbidity, TDS, Fe, total hardness (TH), SO₄^2?, and Mg²⁺ also sometimes exceeded drinking water limits. The TDS, TH and SO₄^2? concentrations of the mine water makes it unsuitable for domestic purposes or for industrial use; high values of %Na, SAR, RSC, and Mg-hazard at certain sites restrict its suitability for agricultural use.     

金矿区尾矿渣周边土壤的重金属污染评价研究

在小秦岭金矿区内选取姚青村、来福沟和毛沟三个具有代表性研究区,采集研究区内尾渣堆及渣堆周围农田样品30个,测定了重金属Cr、Ni、Cu、Cd、Zn、As、Pb含量。对土壤样品重金属测定结果分别采用地累积污染指数法和潜在生态危害指数评价法进行评价,结果显示:As不是矿业活动污染的典型金属;姚青村和来福沟重金属典型污染物为Cu、Zn、Cd、Pb。采用地累积污染指数法评价,姚青村和来福沟的Pb属于极严重污染,而Cr、Ni均属无污染。采用潜在生态危害指数法进行评价,毛沟研究区属轻微生态危害,姚青村和来福沟生态风险程度均属极强,贡献率大的元素主要为Pb和Cd。     

Assessment of Metal Contamination in the Mine Water of the West Bokaro Coalfield,India

This study was carried out in the West Bokaro coalfield area of the Jharkhand state of India to assess water quality for drinking and domestic purposes. Thirty mine water samples were collected from opencast and underground mines, and concentrations of Al, As, Ba, Cr, Cu, Fe, Mn, Ni, Se, and Zn were determined using ICP-MS. Spatial distribution maps were prepared using GIS software so that the quality of the mine water could be easily understood. Metal concentrations were higher in the pre-monsoon season than in the post-monsoon season, irrespective of location, but there were more significant seasonal variations in the opencast mine water than in the underground mine water. The concentrations of Al, Ba, Fe, Mn, and Ni exceeded the desirable as well as the permissible drinking water limits in both seasons. The quality of the surface water as well as the groundwater in the region may be adversely affected by the high metal concentrations in this mine water.     

An Evaluation of Metal Contamination in Surface and Groundwater around a Proposed Uranium Mining Site, Jharkhand, India

The East Singhbhum region is a highly mineralised zone, with extensive mining of copper, uranium, and other minerals. The concentrations of certain metals (Fe, Mn, Zn, Pb, Cu, and Ni) were measured in 10 groundwater locations and eight surface water locations for four seasons during 1 year around a proposed uranium mining area. The ranges of Fe, Mn, Zn, Pb, Cu, and Ni in surface water were 0.08–1.21, 0.02–0.32, 0.02–3.48 mg/L, 0.84–14, 1.25–36, and 1.24–15 μg/L, respectively, while in groundwater, the ranges were 0.06–5.3, 0.01–1.3, 0.02–8.2 mg/L, 1.4–28, 0.78–20, and 1.05–20 μg/L, respectively. Only Fe and Mn were found to exceed India’s drinking water standards. The data have been used to calculate a metal pollution index (MPI). The MPI of both groundwater (28) and surface water (10) is well below the index limit of 100, which suggest that neither is generally contaminated with respect to these metals.     

西南地区某矿产集采区土壤重金属迁移规律及生态风险评价

为科学推进矿山生态修复,依托传统野外调查工作手段与技术优势,结合室内综合测试与系统分析,开 展长江上游金沙江流域内矿产资源开发引起土壤重金属含量变化相关研究。 以西南地区某矿产集采区为例,探索区 内土壤重金属含量及其随流域迁移规律,分析区内土壤重金属潜在生态风险。 研究表明:该矿产集采区铅锌矿区、磷 矿区土壤样品重金属含量超标存在差异;源于矿产资源开采方式、洗选方式、矿区固体废弃物分布、地表径流强度等 诸多因素影响,区内土壤样品重金属含量从上游到下游的迁移规律呈多种类型。 相关结果既可作为生产矿山生态环 境监测的工作依据,亦可作为闭坑矿山生态保护修复的重要参考。     

某铀尾矿库下游农田土壤重金属污染程度及其风险评价

为了解某铀尾矿下游农田土壤重金属污染程度及其潜在生态风险,选取地积累指数法及潜在生态危害指数法来对尾矿库周边下游农田土壤重金属污染状况及其对生态的潜在危害进行综合评价。数据显示：研究区土壤中Cd和U均超出国家背景值,均值分别为国家背景值的6.89倍和3.16倍。同时,Cd和U也高于当地背景值,均值为当地背景值的4.96倍和2.5倍。铀尾矿下游农田9个样品中Cd和U地累积指数值分别介于1.90~2.82之间和0.81~1.46之间。对于Cd,9个样品中有1个样品为轻度污染,8个样品为中度污染。对于U元素,9个样品中有4个样品为轻微污染,5个样品为轻度污染。铀尾矿下游农田综合潜在生态风险程度多为中。总体来看,该农田潜在生态风险较高,主要是Cd和U所带来的潜在生态风险。     

Hydrogeochemistry,Elemental Flux,and Quality Assessment of Mine Water in the Pootkee-Balihari Mining Area,Jharia Coalfield,India

Ninety nine mine water discharge samples were collected and analyzed for pH, electrical conductivity (EC), major cations, anions, and trace metals in the Pootkee-Balihari coal mining area of the Jharia coalfield. The mines of the area annually discharge 34.80 × 10⁶ m³ of mine water and 39,099 t of solute loads. The pH of the analyzed mine waters ranged from 6.97 to 8.62. EC values ranged from 711 μS cm⁻¹ to 1862 μS cm⁻¹, and reflect variations in lithology, geochemical processes, and hydrological regimes in the mines. The cation and anion chemistry indicate the general ionic abundance as: Mg²⁺ > Ca²⁺ > Na⁺ > K⁺ and HCO₃ ⁻ > SO₄ ²⁻ > Cl⁻ > NO₃ ⁻ > F⁻, respectively. Elevated SO₄ ²⁻ concentrations in the Gopalichuck, Kendwadih, and Kachhi-Balihari mine waters are attributed to pyrite weathering. The water quality assessment indicated that TDS, hardness, Mg²⁺, and SO₄ ²⁻ are the major parameters of concern in the study area. Except for Fe, all of the measured metals in the mine water were well within the levels recommended for drinking water. With only a few exceptions, the mine water is of good to permissible quality and suitable for irrigation.