Assessment of Open Pit Dewatering Requirements and Pit Lake Formation for the Kışladağ Gold Mine,Uşak,Turkey

The K??lada? gold mine (U?ak, Turkey) has operated since 2006 and is projected to close by 2030, leaving a large open pit. We quantified dewatering requirements during the operational period, predicted pit lake formation during the post-closure period, and assessed the likely impacts on groundwater resources. Groundwater inflow into the pit during 17 years of mining was calculated using analytical and numerical models. The analytical model yielded lower inflow rates because it does not account for groundwater that will be released from storage. Post-closure, pit lake water balance calculations show that the system will reach equilibrium 585 years after dewatering ceases and that lake levels will stabilize at 816 m above sea level (masl). Further analysis indicated that 830 masl is a critical level, below which the pit will behave as a sink; above that, it will be a flowthrough system that could possibly affect downgradient groundwater quality.     

Prediction of seepage water pressure for slope stability at the Gol-E-Gohar open pit mine

Slope stability accidents are one of the leading causes of destruction at open pit mining operations. Such interception of the seepage water results in the water inflow from the surrounding aquifer towards the mine excavations. In order to design an effective drainage scheme for an open pit mine, prediction of water inflow into the pit is essential. These changes have resulted in some failures and instability problems in different parts of Gol-E-Gohar iron open pit mine. It seems that main parameters which effect the failure and instability of the mine slopes are high pressure of groundwater and system of discontinuities (faults, joins, and bedding planes), which intersect the pit walls. The analysis results indicate that stability of the final pit slopes is sensitive to multi-planar failures and confined water in the walls pit is also a factor adversely affecting the stability. Problems associated with groundwater at the site were also assessed with the analyses of piezometric level and groundwater inflow.     

南泥湖露天矿区采场水力联系及矿坑涌水量预测

为了查明南泥湖露天矿区采场范围内水力联系及矿坑涌水量,分析了含水层类型及其富水性特征,地下水补给、径流、排泄条件,地下水的基本特征等,基于此,采用长期水文监测、示踪试验及水化学分析等方法,研究了大气降水、地表水、地下水及矿坑涌水之间的水力联系及相互转换关系;并分析了露采矿坑的涌水因素以及预测了露采矿坑涌水量,主要包括矿坑大气降水补给量、地表径流量和地下水补给量。研究为后期水文地质监测以及地质灾害防治提供了技术支持。     

Evaluating the Origin of Seepage Water in the Golgohar Iron Mine,Iran

The Golgohar mine produces iron ore from an open pit in south-central Iran that is now more than 100 m below the water table, and dewatering has not solved the mine’s water seepage problem. Previous studies had reported that Kheirabad (Sirjan) Playa, 13 km north of the mine, was the most probable groundwater source. A combination of geological, hydrogeological, hydrochemical, and isotopic techniques were used to evaluate the hydraulic connectivity between the mine and the lake, and to characterize the probable water sources. Thirty-two surface and groundwater samples were collected and analyzed for major and minor (Li, B, and Br) constituents. Ten water samples were analyzed for oxygen-18 and deuterium and three samples were analyzed for tritium. The results indicated that impermeable formations and very low-permeability alluvial deposits lie between lake and the pit. In addition, the chemical and isotopic signatures of the two water sources indicated different origins. Inverse geochemical modeling and the mine water’s isotopic signatures suggest that the water is coming from the surrounding alluvial aquifer, or is deep basin water from within the fractured bedrock, or a mixture of the two.     

长汀矿区矿坑涌水量模糊水文地质比拟法预测

基于长汀矿区勘探资料,分别从含水层组特征、断裂构造带水文地质特征、地下水补给、径流、排泄特征、矿井充水类型等方面对该矿区的水文地质条件进行了分析,结果表明:1矿区侵蚀基准面以上的主要充水来源为大气降水、接触裂隙水和断层接触水;2矿区侵蚀基准面以下的主要充水来源为接触裂隙水和断层接触水;3矿区地下水补给主要来源于大气降水,浅部可直接获得补给,深部通过裂隙和断层间接获得降水补给。在上述分析的基础上,基于矿区用水量实测资料,采用模糊水文地质比拟法、传统水文地质比拟法预测的矿坑涌水量分别约为44.69,46.73m3/h。尽管模糊水文地质法的预测结果略小于传统水文地质比拟法,但由前者充分考虑了降雨量、水头降深、开采面积、给水度、渗透系数和补给水源等因素,故其预测结果相对于传统水文地质比拟法而言可靠性更强。分析结果对于精确预测该矿区矿坑涌水量,确保井下安全开采有一定的参考价值。     

基于Visual Modflow的露天开采区地下涌水量模拟预测

露天开采过程将对地下水循环系统造成影响,目前这方面的定量研究却较少报告。结合四川某铁矿露天开采区水文地质条件,采用Visual Modflow 建立矿区地下水水流模型,分别预测开采至不同标高处的地下水流场变化、地下水涌水量及降落漏斗影响面积。预测结果表明,在露天矿坑周围局部地区地下水流指向开采区域,随着开采年限增长,地下水降落漏斗影响面积从0.54 km²增至1.55 km²,涌水量为3 220~4 565 m³/d,并揭示出地下水涌水量随季节的变化趋势。通过模型预测的定量评价,为矿山疏干采矿及设计防治水方案提供了一定科学依据。     

Estimating the Decant Rate from a Rehabilitated Opencast Colliery Using a Water Balance Approach

The long-term average decant rates from rehabilitated opencast collieries in South Africa are often estimated by assuming effective recharge rates through the spoils. However, large uncertainties are associated with these assumed recharge rates. Furthermore, this approach assumes that groundwater inflows and pit water outflows are negligible compared to the volumes of water recharged through the spoils. To obtain an estimate of the decant rate at a particular colliery, I used rainfall figures, pumping rates, and water elevations measured over a period of 6 months as well as estimated evaporation rates to construct a water balance. I then calculated a decant rate, independent of assumed recharge rates, that was significantly higher than a previous long-term estimate, despite the lower than average rainfall experienced during these 6 months. This discrepancy suggested that groundwater inflow was indeed contributing to the decant volumes. The decant rate during years of average rainfall was subsequently calculated by adding the estimated groundwater inflow to the recharge volumes found with the method based on assumed recharge. This decant rate was approximately 49 % greater than a previous estimate obtained by assuming negligible groundwater inflow. This study shows that the decant rates at rehabilitated opencast collieries could be significantly underestimated if the decants are assumed to be recharge-driven without considering the possibility of groundwater inflow. Underestimation of the decant rates will lead to flawed water management strategies, which could result in adverse environmental impacts.     

Successful Use of Geoelectrical Surveys in Area 3 of the Gol-e-Gohar Iron Ore Mine,Iran

Geoelectrical surveys were conducted in Area 3 of the Gol-e-Gohar iron ore mine to provide geological and hydrogeological information. Open pit mining is currently underway in the northern part of the Area, and underground mining operations are planned for the southern section. Groundwater has already been encountered in the open pit mine. Twenty five resistivity soundings were first performed in the mine area; then, induced polarization (IP) measurements were carried out to remove ambiguities between clay and water-bearing layers. To investigate fault zones as water conduits, combined resistivity profiling surveys were also carried out. These measurements provided a detailed structural map of the pit area. Resistivity and IP results have subsequently been confirmed by observations at three monitoring wells and the mine pit wall. Monitoring and piezometric wells will be drilled at locations suggested by the results of the geoelectrical surveys. Drainage galleries may be developed to dewater the open pit mine. However, another option being considered is to start the underground mining with the idea that it will initially simply serve as a dewatering mechanism.     

露天矿闭坑环境地质灾害危险性分区研究

基于露天矿闭坑前后地质灾害的分析，总结出我国露天煤矿开采至闭坑前环境地质问题与灾害主要有3个方面：① 露天煤矿开采将形成深大的矿坑及废弃矸石排土场.② 露天采矿形成的矿坑边坡及排土场边坡，由于地质构造、边坡岩体、地表水与地下水作用，采矿工程活动等原因诱发一系列诸如滑坡、塌陷、泥石流、周边地面变形、地裂缝等突发性或缓变性地质灾害.③ 露天矿开采引发生态环境恶化及缓变性的灾害.提出了露天矿闭坑环境地质灾害危险性分区的方法.并根据以上研究以抚顺西露天煤矿闭坑（矿坑）环境地质灾害危险性分区为实例进行了分区，得到了符合实际的结果.     

金属矿山地下水零排放技术方法研究

在地下水超采区域内疏干排水采矿将会加剧地下水降落漏斗的扩展、严重破坏区域内地下水生态环境。金属矿山地下水零排放关键技术体系,针对矿山防治水与矿区地下水生态环境综合治理领域所面临的技术难题进行系统性研究,提出了包括采用帷幕注浆、井巷地表预注浆和矿坑水回灌等技术措施的系统方案,并针对其中重要技术参数进行了系统地研究。依托位于邯邢百泉泉域的典型大水矿山中关铁矿进行了实践,取得矿坑水零排放的理想效果,其技术体系原理、技术方法等对于解决国内外大水型矿山面临的紧迫难题提供借鉴。     

白云鄂博东矿境界外资源的开采方案研究

白云鄂博东矿如果可以合理开发利用境界外资源,将延续矿山的生命周期。本文从技术可行性和经济合理性两方面对东矿境界外资源开采方案进行了分析,研究得到:东矿境界外资源开采采用地下开采是唯一选择。在应用Dimine数字矿山软件建立东矿三维地质模型的基础上,根据露天境界外矿体的形态、资源分布情况以及与露天采场的相对位置,研究了地下开采分区。为实现东矿露天转地下不停产衔接,南部境界外挂帮矿采用露天采场内平硐开拓并率先实施,北东境界外挂帮矿开采随后实施,露天坑底境界外开采最后实施。露天矿境界外挂帮矿体的回采不仅充分回收了国家矿产资源,还为露天矿山可持续发展提供了新的途径。     

Using Multiple Methods to Predict Mine Water Inflow in the Pingdingshan No. 10 Coal Mine,China

To ensure safe mining of the no. 2 coal seam in the Pingdingshan No. 10 coal mine, three methods (analogue, big well, and numerical simulation) were used to forecast mine water inflow and their performance. The big well method predicted the largest water inflow: 233.8 m³/h in the ?230 m level and 281.1 m³/h in the ?300 m level. The numerical simulation predicted the least inflow, 205.7 and 228.6 m³/h respectively for the 230 and ?300 m levels; this was closest to the measured values. Based on this work, it appears that combining numerical simulations with other methods are a good way to accurately forecast mine water inflow.     

柠条塔矿区南翼S1210工作面涌水机制分析

柠条塔煤矿作为陕北矿区中开采侏罗系延安组煤层的矿井,涌水量一般不大,但2011年5月30日发生了涌水事故,查明涌水事故原因至关重要。通过地下水位观测、水文地质钻探等手段,进行了地面水文地质条件探查,总结了地表水系水位变化情况及地下水水位动态特征;结合现场放水试验、地下水连通试验,详细分析含隔水层特性,即含水层厚度、裂隙发育、富水性及变化规律。最终确定了涌水水源是工作面上覆侏罗系中统直罗组风化基岩裂隙承压水,涌水通道为西北部连续分布粗—中粒砂岩。     

新疆北部某煤矿考虑采掘进度的矿井涌水量动态模拟预测

为了更为准确地模拟预测新疆北部某煤矿1号矿区在分区分层开采过程中的矿井涌水量,在分析研究1号矿区的工程地质、水文地质等详细资料的基础上,运用目前主流的地下水数值模拟软件GMS中的Modflow模块对矿井进行三维建模仿真,结合1号矿区的采掘计划和采掘进度,模拟了该矿井在采掘期(10年)的动态涌水量,同时运用矿井的实测涌水量进行了对比验证。最终将考虑采掘进度模拟预测的涌水量、未考虑采掘进度模拟预测的涌水量、大井法计算涌水量、实测涌水量进行了对比分析,结果显示考虑采掘进度模拟得到的涌水量更为接近实测涌水量,验证了考虑采掘进度模拟矿井动态涌水量方法的准确性和优越性。     

露天边坡地下水渗流模拟及降水坡降研究

以伊敏露天矿三采区设计采矿为工程研究背景,采用物理模拟与数值模拟相结合的方法,分析地下水渗流规律、边坡采动渗流变形规律、及降水对边坡渗流规律影响。基于相似模拟研究了露天开采过程中地下水位渗流动态过程、坡面出水位置、渗流水力坡降特征及地下水通过断层后出现水位跃变;通过数值模拟研究了7种不同降水工况中边坡中浸润线的变化特征、地下水在断层处跃变规律、及地下水的水力坡降特征。最终,确定了矿区合理的降水位及水力坡降。     

Assessment of Dewatering Requirements and Dewatering Well Design for an Open Pit Coal Mine in Central Anatolia

The Çeltikçi Coal Basin is a newly discovered coal basin in Central Anatolia where 11 years of open-cut mining has been planned. The bulk of the mining will be conducted below the regional water table; hence, determination of the dewatering requirements and proper design of the dewatering wells plays a critical role. This study (i) defined the dewatering requirements of the open-pit mine, (ii) established a dewatering well design for the area, and (iii) assessed the anticipated impacts of the dewatering activities. For this purpose, a 3-D numerical groundwater flow model was developed using the FEFLOW software. Yearly dewatering requirements were determined under transient conditions. For the dewatering well simulations, two types of dewatering wells were considered: permanent wells located at the open pit boundary that would increase in number as the excavation proceeds and wells located at the periphery of the yearly excavated area that would be operational for about two years. The simulation results indicated that 894 wells were required to satisfy dry working conditions; the average pumping rate throughout the mine life was calculated as 322 L/s. The impacts of open-pit dewatering on groundwater resources were assessed in terms of spring discharge and base flow rates in the nearby Kirmir stream. As a result of dewatering, most of the village water supply springs and fountains will dry up in the area. In addition, the base flow rates to the Kirmir stream will be decreased by 15%.

     

大红山铁矿露天采场压矿范围的相似模拟

云南大红山铁矿由于露天采场的压矿限制,井下二期工程无法稳产至露天开采结束,压矿问题使矿山的开采无法实现顺利过渡。为研究矿山露天采场合理的压矿范围,通过相似材料模拟试验对大红山铁矿无底柱分段崩落法开采进行模拟。基于相似模拟试验过程中的模型岩层移动的变形情况、应力变化和位移变化数据,结合当前矿山现场数据进行综合分析,得到了矿山空区的冒落形式、露天采场最可能的破坏形式以及70°的压矿角度。根据70°压矿角重新划定露天采场合理的压矿界限,井下二期工程可以在安全的状况下多服务2 a,此时露天采场开采已结束,井下二期工程不再受露天采场的压矿限制,从而实现露天采场与井下开采的顺利过渡。研究结果为合理协调矿山开采、保障矿山安全提供了较好的理论依据,为类似露天地下联合开采的矿山提供了借鉴。     

Groundwater Source Discrimination and Proportion Determination of Mine Inflow Using Ion Analyses: A Case Study from the Longmen Coal Mine,Henan Province,China

Complex hydrogeological conditions in China’s coal mines have contributed to frequent mine water disasters. A simple and effective method to determine water inflow sources and paths is therefore essential. The Longmen Mine, located in Henan Province, in central China was used as a case study. A Piper diagram and cluster analysis were used to screen the characteristic values of 18 water samples from potential aquifers. A comprehensive fuzzy evaluation of the groundwater ions was carried out to determine the main source of the total mine inflow. Then, based on conservation of ionic masses, a matrix function was established to calculate the groundwater recharge composition. Finally, using measured water inflows for the Cambrian limestone aquifer, the calculated and observed results were compared. The results showed that the Carboniferous Taiyuan Formation limestone aquifer (the L₇ limestone aquifer) accounts for 60.8% of the total mine inflow, while the Cambrian limestone and roof sandstone aquifers account for 34.8 and 4.4% of the inflow, respectively. The normal mine inflow totals about 19,200 m³/day, of which 6,840 m³/day is from the Cambrian limestone aquifer. This agrees well with the calculated value of 6,720 m³/day. Thus, the method is feasible and reliable.     

Combined Use of Geostatistics and Multi-Criteria Decision Analysis to Determine New Pumping Well Locations in the Gol-Gohar Open Pit Mine,Iran

Groundwater seepage into open pit mines must be controlled carefully. Slope instability, dewatering of blast holes, and mining operations below the groundwater table are important issues caused by groundwater seepage into the Gol-Gohar open pit mine, Iran. There are several methods to overcome these problems, such as construction of cut-off walls, ditches and sumps, horizontal drains, and pumping wells. Drilling of a new pumping well has several difficulties in which the determination of its location is a major issue. In this study, a stochastic simulation approach called simulated annealing was used to determine the best possible locations for new pumping wells. Three major groundwater variables, including the groundwater level, electrical conductivity, and transmissivity were selected for the geostatistical study. The results of simulations showed reliable correlation (Pearson) between the variables. Comparison of the variograms at different depths of the Gol-Gohar pit mine revealed that the effect of faults intensified with increasing depth. The best potential locations for drilling of new pumping wells were identified by the use of multi-criteria decision analysis performed on the simulation results. This method can be used in other regions with similar hydrogeological settings.     

薛湖煤矿矿井充水主控因素与矿井涌水量预测研究

河南薛湖煤矿在开采过程中受到了水害的影响,为了确保煤矿安全、高效生产,分析了矿井水文地质条件,研究了矿井冲水的主控因素,并对矿井涌水量进行预测计算。研究结果表明,薛湖煤矿矿区发育六大含水层（组）和三大隔水层（组）,煤系地层的二叠系砂岩裂隙含水层是危害矿井生产的主要含水层,随着生产的进行,顶板砂岩水多被疏干,对生产的安全不会造成很大的影响。二2主采煤层的直接充水水源为二叠系二2煤层顶板砂岩裂隙承压水,间接充水水源为二2煤层底板和奥陶系灰岩岩溶裂隙承压水,矿井的自身采空区积水是薛湖矿的充水水源之一。二2煤的导水途径主要有裂隙、断层和封闭不良钻孔3种,高角度正断层可能成为导水通道。越往深部开采水压将会越大,构造和裂隙的发育增加了底板水涌入矿井的危险。选取比拟法和稳定流解析法对采区矿井涌水量进行计算,比拟法计算的全矿井正常涌水量656 m 3/h、最大涌水量787 m 3/h比较符合近年来矿井充水的实际情况,可以作为下一步矿井开采的依据。但随着开采水平的不断延深,太灰岩溶水向矿井突水的概率也将大大提高,若出现短期内多点突水情况,将会超过比拟法预算的最大涌水量。