鄂尔多斯盆地煤-水协调开采下矿区水资源异位回灌-存储技术思路

Technical thinking on ectopic injection and storage of mine area water resources under the coordinated exploitation of coal and water background in Ordos Basin

鄂尔多斯盆地侏罗系煤层开采过程中矿井涌水量不断增大,为缓解矿井水深度处理成本持续增加、矿井水难以较大规模处理等问题,立足于煤-水协调开采、保水采煤等科学理念,提出在研究区内开展矿井水深井回灌试验性研究。阐述了鄂尔多斯盆地煤层开采与水资源保护间的矛盾问题,包括矿井水害防治、区域水资源保持、矿区生态环境保护3者间的关系;结合对研究区38座煤矿矿井水水质特征的调研统计,阐明了煤-水协调开采下的矿井水处理的瓶颈问题。结果表明:研究区矿井水常规离子超标占比68.4%,铁、锰超标占比20%,且高盐高氟,导致矿井水处理无法同时满足较低成本、大规模的需求。提出了煤矿区“三减一治”的水资源异位回灌保水技术思路,包括充水含水层水资源异位回灌、采空水异位回灌、露天矿坑水异位回灌及含特殊组分矿井水异位回灌,并对其试验性研究的可行性进行了定性比较。然后,结合鄂尔多斯盆地某矿超深回灌存储的工程案例,总结得出了超深存储相关的理论与技术框架、技术内容、技术难点,建成了研究区高矿化度矿井水超深回灌-存储的示范工程。基于对全国87座煤矿TDS和133座煤矿pH的统计分析,提出将弱酸弱碱(44%)、高矿化度矿井水(69%)进行超深回灌存储,以减少对地下水资源的消耗、浪费及对煤矿区水生态环境的影响,同时降低矿井水治理成本,指出矿井水深井回灌在华北区甚至全国煤矿区具有较高的推广应用价值。

During the process of Jurassic coal mining activities in the Ordos Basin, the mine water inflow is constantly increasing. In order to alleviate the problems such as the increasing expenditure of mine water advanced treatment and the difficulty of large-scale treatment, an experimental investigation on mine water deep injection was put forward based on the scientific concepts of coal-water coordinated mining and water-preserved coal mining in the study area. Firstly, the contradictions between coal mining and water resources protection in the Ordos Basin were expounded, including the relationship among mine water disaster prevention, regional water resources preservation and ecological environment protection in mine areas. Secondly, the bottleneck problems of mine water treatment under the coordinated development of coal and water were clarified combined with the investigation and statistics of the water quality characteristics of 38 coal mines in the study area. The conventional ions in mine water exceeding the standard Ⅲ value of Standard for Groundwater Quality(GB/T 14848—2017) account for 68.4%, meanwhile iron and manganese account for 20%, and the characteristics of high salt and high fluorine were obvious in the study area. At present, the mine water treatment cannot meet the demand of relatively low cost and large scale at the same time. Then, the authors put forward "three decrement and one treatment" technical approaches of water resources protection and ectopic injection in the mine areas, including mining related aquifers ectopic injection, mined-out space water ectopic injection, open pit water ectopic injection and mine water with special components ectopic injection, and the feasibility of the experimental research is qualitatively compared. The authors expounded in detail the theory and technology framework, technical contents and technical bottlenecks about ultra-deep injection and storage, and conducted a demonstration project for high TDS(total dissolved solid) mine water treatment in the study area, based on the engineering in-situ case of ultra-deep injection and storage at a mine in the Ordos Basin. Finally, the authors proposed that weak acid and weak alkali(44%) and high TDS mine water(69%) should be stored by ultra-deep injection derived from the statistical analysis of the TDS values of 87 coal mines and the pH values of 133 coal mines in China, so as to reduce the consumption and waste. At the same time, the cost of mine water advanced treatment is reduced. This paper pointed out that mine water deep injection has significant application value in Northern China, and even some other coal mining areas of China.