煤矸石模拟浸泡和淋溶实验污染物释放特点的研究

通过浸泡实验和淋溶实验研究贵州百里杜鹃风景区煤矸石堆场的煤矸石溶解释放污染物的规律。结果表明,煤矸石模拟淋溶渗透水与煤矸石浸泡液中释放的主要污染物一致,主要污染物为硫酸盐(SO42-)、总铁(Fe)和锰(Mn)且pH值低。模拟淋溶实验的淋滤初期,淋滤液中主要污染组分浓度较高,以后随着降水量的增加,从煤矸石中溶出的有害污染物质的量减小,在淋溶初期污染物质溶出的浓度最高。煤矸石的浸泡实验中,浸泡液中主要污染组分浓度较高,随着时间的增加,煤矸石中的污染物不断地释放出来。     

水-土相互作用对浅层地下水硬度升高的影响

浅层地下水硬度呈逐渐升高的趋势,已成为地下水污染的一个普遍问题。设计淋溶试验模拟水-土相互作用的过程,研究地下水硬度升高的机理,对区域地下水水质保护、地下水资源合理开发利用都是十分必要的。试验使用的水样采自地下水,土样包括污染土、农田土、清洁土。试验结果表明:水-土相互作用会导致淋滤液总硬度升高,淋滤液中易溶盐、K+、Na+阳离子及TDS和硬度生成有密切的关系;在水-土相互作用过程中发生溶解作用、阳离子交换作用和盐效应,导致游离态钙镁,交换态钙镁及化合态钙镁进入地下水,引起地下水总硬度升高。     

燃煤灰渣中砷的连续柱淋滤特性及表生运移作用初探

采用连续柱淋滤试验装置对高砷煤燃烧灰渣进行动态淋滤实验研究,用模拟酸雨淋溶土柱的试验方法探讨煤及燃煤灰渣对土壤的污染及表生运移作用,重点研究燃煤灰渣在不同酸度模拟酸雨条件下对污染土壤中重金属元素砷的淋滤液性质影响。高砷煤燃煤灰渣的动态淋滤实验表明,灰渣淋滤受体系、pH值、吸附和共沉淀作用等因素的影响,高砷及中砷煤灰在淋滤初期其砷的阶段淋滤浓度升幅均较大,但不同的煤灰出现砷淋滤浓度高峰值的时间点有所不同。针对同一燃煤灰渣,淋滤液酸性越强,灰渣中砷的阶段淋滤浓度相对较大,但均属弱淋滤强度。模拟酸雨作用于土壤之上的煤样或灰渣时,随着模拟酸雨酸性的增强,其淋滤液中砷的阶段淋滤率呈递增趋势;中砷灰或中砷煤中砷的阶段淋滤率和60 h总淋滤率分别小于0.5%、2%,属弱淋滤强度。淋滤液的酸性越强,煤及其燃烧灰渣在堆积过程中对土样中渗透砷含量的能力越高。含砷量较高的煤及其燃烧灰渣在堆积或利用过程中通过雨水等自然界长期淋滤作用有可能产生砷危害的累积效应。     

韩城矿区矿山固体废弃物淋滤试验研究

以矿山固体废弃物为研究对象,利用自主研制的淋滤仪器,模拟自然降雨对矿山废石的淋滤过程,探索污染元素及其淋滤规律。试验结果表明:(1)不同试验条件下的淋滤液电导率k变化趋势相同,k—t曲线整体呈下降趋势;(2)对于pH值,新鲜和风化废石有明显不同的淋滤规律;(3)不同试验条件下的淋滤液SO_4~(2-)浓度c变化趋势相同,c—t曲线整体均呈下降趋势;(4)相同风化程度下,降雨强度越大,淋滤液k越小,c越小,pH值变化不明显;(5)相同降雨强度下,风化程度越高,淋滤液k越大,c越大,pH值越低;(6)综合来看,风化程度对于淋滤液的k、pH值、c等的影响均大于降雨强度的影响。     

演马电厂粉煤灰矿井填充对地下水环境影响的模拟实验

对演马电厂粉煤灰进行浸泡和淋溶试验,模拟矿井填充后其对地下水环境的影响。测定了pH值,电导率,F-,总硬度,Zn,Mn,Cr6+,Cd,Cu,Pb等项目,实验表明,流动水体利于污染组分的溶出和迁移,溶出液中高锰酸盐指数和Cr6+超标,pH值偏高,淋溶条件下TDS和氯化物超标,对地下水环境存在污染。其它重金属元素含量甚微,多未检出。     

粒径对煤矸石污染物溶解释放规律影响研究

为研究粒径对不同地区煤矸石污染组分溶解释放规律的影响,以山西省和辽宁省3个煤矿区的4种煤矸石为试验材料,通过静态浸泡试验,分析了不同粒径、不同浸出时间条件下4种煤矸石浸出液的pH,氧化还原电位(ORP),电导率,总硬度,Fe2+、Mn2+、SO24-浓度等指标变化。结合X-射线衍射和扫描电子显微镜检测,阐明不同地区煤矸石污染组分溶解释放的机制。结果表明:在粒径为0.18～0.25 mm时,4种煤矸石释放的污染物量均达到较大值。阜新海州地区自燃煤矸石和海州地区原煤矸石的浸出液p H呈碱性,阜新高德地区自燃煤矸石和山西某矿原煤矸石的浸出液p H呈酸性。阜新高德地区自燃煤矸石浸出液的总硬度和SO24-质量浓度分别为589、529 mg/L,山西某矿原煤矸石浸出液的Fe2+质量浓度为10.79 mg/L,阜新海州地区自燃煤矸石浸出液的Mn2+质量浓度为1.97 mg/L。煤矸石的表面存在孔隙、附着细小颗粒,且包含的沸石、黄铁矿、绿泥石、高岭石和磁铁矿等矿物容易溶解,向水中释放污染物。煤矸石粒径越小污染物越容易溶解释放;浸出0～3 d内污染物容易溶解释放,后期释放量趋于平稳。建议矿区施工时保持煤矸石的粒径大于0.18～0.25 mm,以减少煤矸石在堆积和填充复垦过程中向土壤和地下水释放污染离子。     

煤矸石填充矿井对地下水环境影响的因子分析评价

以平煤十二矿煤矸石为研究对象,进行了煤矸石矿井填充对地下水环境影响的淋溶模拟实验。针对室内模拟试验结果,选择pH值、F-、SO42-、总硬度、Mn、Pb、As、Hg和电导率9指标,应用因子分析法对煤矸石淋出实验结果进行了综合评价分析,提取4个主因子。评价结果表明:利用中等粒径(3~25 mm)煤矸石填充矿井,对地下水环境的影响程度较低。     

贵州某磷尾矿充填体泌水的模糊综合评价

为了考察磷尾矿充填井下后,充填体泌水对井下环境的污染情况,以贵州省某磷矿浮选尾矿为骨料制备充填材料,收集其充填体泌水进行研究分析和模糊综合评价。评价结果表明,4种不同配比充填体的泌水对地下水的污染程度均为V级,其主要污染因子为SO42-和总硬度,两者的污染影响权重达到70%;次要污染因子为pH和F-。     

磷矿浮选回水中SO_4~(2-)及总硬度去除试验研究

为解决离子在浮选回水中的积累问题,采用混凝沉淀法去除磷矿浮选回水中的SO42-及总硬度。研究结果表明:pH值对混凝效果影响较大。利用石灰乳调节废水pH值至8后,采用Na2CO3、PAC与PAFC联用处理工艺效果较好,Na2CO3、PAC和PAFC的适宜投加量分别为2000mg/L、600mg/L和1400mg/L,在此条件下,SO42-和总硬度去除率分别达到70.15%和85.05%。     

SRB治理地浸采铀矿山污染地下水条件试验研究

地浸采铀过程中,由于溶浸剂的注入,改变了地下水的原始地球化学环境,使得地下水中铀及重金属离子的浓度增高,造成了地下水的污染。通过室内试验,参照污染地下水化学成分,研究了pH值对硫酸盐还原菌(SRB)还原SO42-的影响以及SRB对U、Mn2+、Zn2+、Pb2+、Fe2+等的去除效果。结果表明,溶液pH值对SRB还原SO42-的能力以及SRB去除U、Mn2+、Zn2+、Pb2+、Fe2+等的效果影响很大,当pH值为8时,SO42-还原能力和U、Mn2+、Zn2+、Pb2+、Fe2+的去除效果均达到最佳,为地浸采铀矿山污染地下水的治理提供了新的思路。     

Geochemistry,Hydraulic Connectivity and Quality Appraisal of Multilayered Groundwater in the Hongdunzi Coal Mine,Northwest China

This study assessed the geochemistry and quality of groundwater in the Hongdunzi coal mining area in northwest China and investigated the mechanisms governing its hydrogeochemistry and the hydraulic connectivity between adjacent aquifers. Thirty-four groundwater samples were collected for physicochemical analyses and bivariate analyses were used to investigate groundwater quality evolution. The groundwater in the mine was determined to be neutral to slightly alkaline, with high levels of salinity and hardness; most samples were of SO₄·Cl–Na type. Fluoride and nitrate pollution in the confined aquifers were identified, primarily sourced from coals. Natural geochemical processes, such as mineral dissolution, cation exchange, and groundwater evaporation, largely control groundwater chemistry. Anthropogenic inputs from agricultural and mining activities were also identified in both shallow unconfined aquifers and the deeper confined aquifers, respectively. It was determined that the middle confined aquifer has a high hydraulic connectivity with the lower coal-bearing aquifer due to developed fractures. Careful management of the overlying aquifers is required to avoid mine water inrush geohazards and groundwater quality deterioration. The groundwater in the mining area is generally of poor quality, and is unsuitable for direct human consumption or irrigation. Na⁺, SO₄^2?, Cl^?, F^?, TH, TDS, NO₃^?, and COD_Mn are the major factors responsible for the poor quality of the phreatic water, while Na⁺, SO₄^2?, F^?, and TDS are the major constituents affecting the confined groundwater quality. This study is beneficial for understanding the impacts of coal mine development on groundwater quality, and safeguarding sustainable mining in arid areas.     

Research on mechanism of groundwater pollution from mine water in abandoned mines

In order to understand the mechanism and regularity of the groundwater contamination from mine water of abandoned mines, experiments were conducted on an abandoned coal mine in Fuxin, a representative city with lots of mine water in northeast China. The groundwater pollution from different contaminants of coal-mining voids (total hardness, SO₄²⁻, Cl⁻ and total Fe) and pollution factors transportation situation in the coal rock were simulated by soil column experiment under the conditions of mine water leaching and main water leaching (similar to rainwater leaching), and the water-rock interaction mechanism was discussed during mine water infiltration through saturated coal rock by application of principle of mass conservation, based on physical properties of coal rock, as well as monitored chemical composition. The results show that, compared with the clear water leaching process, trends of change in pollutant concentrations presented different characteristics in the mine water leaching process. Groundwater is contaminated by the water rock interactions such as migration & accumulation, adsorption & transformation, dissolution & desorption and ion exchange during the mine water permeation. The experiments also suggest that at first dissolution rate of some kinds of dissoluble salts is high, but it decreases with leaching time, even to zero during both the mine water leaching and main water leaching. Supported by the National Natural Science Foundation of China(50434020, 50374042), Science & Technology Found of Liaoning Province (20022155); Specialized Research Fund for the Doctoral Program of Higher Education (20040147003)     

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.     

Quality Assessment of Mine Water in the Raniganj Coalfield Area,India

In a qualitative assessment of mine water from the Raniganj coalfield, 77 mine water samples were analyzed to assess water quality and suitability for domestic, industrial, and irrigation uses. The pH of the mine water ranged from 6.5 to 8.8. Total dissolved solids (TDS) ranged from 171 to 1,626 mg L⁻¹; spatial differences between the TDS values reflect variations in lithology, activities, and prevailing hydrological regime. The anion chemistry was dominated by HCO₃ ⁻ and SO₄ ²⁻. On average, Cl⁻ contributes 10 and 19% of the total anionic balance, respectively, in the Barakar and Raniganj Formation mine water. F⁻ and NO₃ ⁻ contribute <2% to the total anions. The cation chemistry is dominated by Mg²⁺ and Ca²⁺ in the mine water of the Barakar Formation and Na⁺ in the Raniganj Formation mines. Much of the mine water, especially of the Barakar Formation area, has high TDS, total hardness, and SO₄ concentrations. Concentrations of some trace metals (i.e. Fe, Cr, Ni) were found to be above the levels recommended for drinking water. However, the mine water can be used for irrigation, except at some sites, especially in the Raniganj Formation area, where high salinity, sodium adsorption ratio, %Na, residual sodium carbonate, and excess Mg restrict its suitability for agricultural uses.     

Environmental Geochemistry and a Quality Assessment of Mine Water of the West Bokaro Coalfield,India

Mine water from the West Bokaro coalfield was qualitatively assessed with respect to domestic and irrigation criteria. Thirty water samples from different mines were collected and analyzed for pH, electrical conductivity, total dissolved solids (TDS), total hardness, major cations, anions, and dissolved silica. The pH of the samples ranged from 6.6 to 8.3 in the post-monsoon season and 6.7–8.4 in the pre-monsoon season, indicating its near-neutral to slightly alkaline nature. TDS ranged from 349 to 1029 mg L^?1 in the post-monsoon season and 499–1458 mg L^?1 in the pre-monsoon season. The spatial differences in TDS reflect the local lithology, surface activities, and hydrology. Ca–Mg–SO₄ and Ca–Mg–HCO₃ were the dominant hydrogeochemical facies; SO₄ ^2? and HCO₃ ^? were the dominant anions and Ca²⁺ and Mg²⁺ were the dominant cations during both seasons. High SO₄ ^2? concentrations are attributed to oxidative weathering of pyrite and gypsum dissolution. Computed supersaturation with respect to dolomite and calcite for most samples may result from the dissolution of gypsum after the water is saturated with respect to the carbonate minerals. Despite moderate to high TDS, total hardness, and SO₄ ^2? concentrations, most of the sampled mine water was of good to permissible quality for irrigation; however, locally higher salinity and Mg restrict its suitability for irrigation at some sites.     

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.     

Hydrogeochemical Processes of Carboniferous Limestone Groundwater in the Yangzhuang Coal Mine,Huaibei Coalfield,China

We examined the primary mechanisms controlling water quality evolution in the Carboniferous aquifer in the Yangzhuang coal mine (Huaibei coalfield). Q-mode factor analysis explained how the Na⁺ and SO₄^2? concentrations gradually increase and the hydrochemical type transforms from Ca-HCO₃ to Ca·Na-HCO₃ and Ca·Na-HCO₃·SO₄ along the flow path. The high bicarbonate concentration appears to be due to dissolution of calcite and dolomite and an open carbonate system, while frequent water inrushes and the declining water level provide evidence for the relative closure of the Carboniferous limestone aquifer. Gypsum dissolution is the main SO₄^2? source. Inverse geochemical modeling sufficiently explained the hydrogeochemical processes that control the water quality evolution. These findings should aid the interpretation of groundwater hydrochemical evolution and groundwater quality management in the study area and other north China coalfields.

     

Groundwater Geochemical Variation and Controls in Coal Seams and Overlying Strata in the Shennan Mining Area,Shaanxi, China

Water resource conservation and ecological protection are key coal mining issues in northern Shaanxi Province and the Yellow River Basin. Revealing the characteristics and variation patterns of groundwater quality in the coal series and its overlying aquifers can provide a geological foundation for solving or optimizing these issues. Taking the Zhangjiamao coal mine of the Shennan mining area in northern Shaanxi Province, western China, as an example, water samples were collected for analysis from the: quaternary strata, weathered bedrock, burnt rock, coal series, and coal seam. Test parameters included conventional ion concentrations, total dissolved solids (TDS), and pH. Key water chemistry indicators such as oxidation/reduction index (ORI) and groundwater chemical closure index (GCCI) were used to explain the water quality differences. The Quaternary water, burnt rock water, and weathered bedrock water were dominantly the Ca–HCO₃ type, the coal series water (Yan’an Formation) was dominantly Ca–HCO₃ and Na–Cl types, and the coal seam water was dominantly Na–Cl type. From the shallow groundwater to coal seam water, dissolution and leaching gradually decrease and degree of retention gradually increases. Coal seam water was characterized by high TDS, high GCCI, and low ORI, reflecting a closed hydrogeochemical environment and moderate sulfate reduction. Leaching, salt accumulation, sulfate reduction, and cation exchange jointly control the groundwater chemical characteristics and evolution of the coal series and its overlying aquifers. Salt accumulation and cation exchange reactions of the stagnant coal seam water in the arid and semiarid climates and shallow buried conditions result in increased mineralization; the water quality is vastly different from that of the overlying aquifers, which are dominated by leaching. Groundwater circulation in the coal series and coal seam are of the infiltration–retention type, and the overlying aquifer of the coal series are of the infiltration–runoff type. A comprehensive hydrogeological model was constructed of the Middle Jurassic coal series and its overlying aquifers in the area. The results of this study have implications for the identification of mine water influx sources in the Shennan mining area, and the understanding of controls on the groundwater geochemical variation in Jurassic coal field of western China.

     

Hydrogeochemical Evolution of an Ordovician Limestone Aquifer Influenced by Coal Mining: A Case Study in the Hancheng Mining Area,China

Statistical analysis was used to study the hydrogeochemical evolution of an Ordovician limestone aquifer group in the Hancheng mining area. Before mining, the groundwater flowed from northwest to southeast, the water type was primarily SO₄–HCO₃, and was mainly controlled by the tectonic structure and the specific hydrogeological conditions. After 40 years of mining, two large groundwater depression cones had formed, centered on the Sangshuping and Xiangshan coal mines in the north and south zones, respectively. The groundwater dropped by ≈?20 m in the center of the depression cones due to over-exploration and mine water inrush, which changed the groundwater flow field significantly. Both the total dissolved solids and the concentrations of major ions increased 2.3- to 4.7-fold, and the water type changed to SO₄–Cl. The saturation indices (SI) of the minerals along the two simulated paths both increased, indicating that the groundwater would dissolve minerals as it flowed, which verified the groundwater flow field. Groundwater quality deteriorated due to a mixture of old acidic pit water and hypersaline water intruding from the deep district. When studied vertically, the concentrations of major ions and SI of calcite and limestone increased, due to the limited cycling of water from shallow to deep. The coincidental Ca²⁺ and Mg²⁺ increases were caused by calcite-replacing dolomitization reactions. To summarize, long-term coal mining adversely affected the area’s groundwater flow field and hydrogeochemical evolution, and effective action should be taken to prevent the Ordovician groundwater from continuing to deteriorate.