露天矿地下水库人工回灌介质渗透性与水质变化规律研究

Study on the regular pattern of medium permeability and water quality variation during artificial recharge of open-pit mine groundwater reservoir

针对矿井水人工回灌过程中水质演化及介质堵塞两大现实问题,通过自主搭建的矿井水人工回灌试验平台,开展矿井水人工回灌地下水库模拟试验。采用单一变量的试验方法,改变矿井水入库前的预处理方式,结合回灌前后矿井水浊度、TDS、悬浮物粒径及SEM扫描电镜,分析了地下水库连续储水过程中的水质变化规律,厘定了地下水库进水水质要求,并总结了露天煤矿地下水库自净化的主要机制;在此基础上研究了不同浊度矿井水人工回灌过程中介质渗透性变化规律,探查了矿井水人工回灌堵塞发生位置及堵塞类型,提出了地下水库自净化与介质渗透性间的矛盾关系。研究结果表明:采用混凝法对入库矿井水进行预处理,可以通过吸附架桥作用有效增大矿井水中悬浮微粒的粒径,进而淤积在回灌介质表层,促进了悬浮物在此阶段的去除,实现了地下水库的自净化,在地下水库连续储水过程中,水中浊度及TDS会进一步降低;但是从介质渗透性变化的角度而言,水中悬浮颗粒在被去除的同时缩短了回灌系统达到堵塞的时间,主要由于回灌介质表层发生了悬浮物堵塞,且回灌介质渗透性变化存在周期性规律,可采用0~5 cm表层清淤和30 h周期性回扬的技术手段消除介质渗透性下降对回灌系统的影响。

Based on the scientific problem of self-purification of underground reservoirs in open-pit coal mines and the self-built experimental platform of artificial recharge of mine water,this paper conducted research on water quality and permeability in the process of artificial recharge of mine water,and the simulation artificial recharge experiment of mine water underground reservoir was carried out.Using a single-variable experimental method,changing the pretreatment method of mine water before storage,combining mine water turbidity,TDS,particle size of suspended solids and SEM scanning electron microscopy before and after recharging,the water quality changes during continuous water storage in underground reservoirs were analyzed.According to the law,the water quality requirements of underground reservoirs were determined,and the main mechanism of self-purification of underground reservoirs in open-pit coal mines was summarized.According to achieved results,the law of media permeability changes in the process of artificial recharge of mine water with different turbidity was studied.The location and type of blockage caused by artificial recharge of water were the first to put forward the contradictory relationship between the self-purification of underground reservoir and the permeability of medium.The research results show that the use of coagulation method to pre-treat the mine water can effectively increase the particle size of suspended particles in the mine water through adsorption and bridging.In the process of continuous water storage in the underground reservoir,the turbidity and TDS in the water will be further reduced.However,from the perspective of the change of media permeability,the suspended particles in the water are removed and shortened at the same time.The time when the recharge system reaches the blockage is mainly due to the blockage of suspended matter on the surface of the recharge medium,and the permeability change of the recharge medium has a periodic law.The techniques of 0-5 cm surface dredging and30-hour periodic reversion can be used as effective means to eliminate the impact of reduced media permeability on the recharge system.