煤矿地下水库水岩作用时间规律模拟试验研究

矿井水在煤矿地下水库的停留时间会影响出水中离子浓度水平，而煤矿地下水库运行期间的水岩作用时间规律尚不明晰。为揭示煤矿地下水库不同运行阶段水岩作用的发生类型及强度，结合现场采样测试分析，设计细砂岩–矿井水(S-K)和泥岩–矿井水(N-K)2组水岩相互作用静态模拟试验，从试验前后岩石成分变化及水中主要离子变化2个方面解析水岩作用类型，并结合Q型聚类分析探讨水岩相互作用的时间规律。岩石矿物成分变化表明，水岩作用过程中发生了钠长石、正长石等矿物的溶解以及高岭石、石英等矿物的沉淀；离子比值分析与统计学分析表明，水岩作用过程中还发生了阳离子交换反应以及硅酸盐、蒸发岩等矿物的溶解和碳酸钙矿物的沉淀；Q型聚类分析表明，静态模拟试验水样样本按时间序列可划分为3类，分别代表水岩作用前期(0～0.5 d)，中期(1～10 d或1～8 d)以及后期(12～47 d或10～47 d)。结合离子来源解析综合判定：在本试验中，水岩作用前期以阳离子交换反应为主，离子变化主要表现为Na+浓度激增，而Ca2+浓度锐减；中期以阳离子交换反应与矿物溶解-沉淀为主，离子变化主要表现为Na+、K+、Cl-浓度增高，Ca2+、HC...

Study on the time law of water-rock interaction in coal mine groundwater reservoir

The retention time of mine water in the coal mine underground reservoir will affect the ion concentration of effluent, but the time law of water-rock interaction during operation of the reservoir is still unclear. In order to reveal the occurrence type and intensity of water-rock interaction in different operation stages of coal mine underground reservoir, two groups of static simulation tests of water-rock interaction were designed based on the test and analysis on-site samples, namely the fine sandstone-mine water (S-K) and mudstone-mine water (N-K). The types of water-rock interaction were analyzed from two aspects: the change of rock composition and the change of main ions in water before and after the test. Meanwhile, the time law of water-rock interaction was analyzed and discussed with the Q-type cluster analysis. The change in mineral composition of rock shows that the dissolution of albite, orthoclase and other minerals and the precipitation of kaolinite, quartz and other minerals occurred in the process of water-rock interaction. The ion ratio analysis and statistical analysis show that the cation exchange reaction, the dissolution of minerals (such as silicate and evaporate) and the precipitation of calcium carbonate minerals also occur in the process of water-rock interaction. In addition, the Q-type cluster analysis shows that the water samples of static simulation test can be divided into three categories according to the time series, representing the early stage of water-rock interaction (0-0.5 days), the middle stage (1-10 days or 1-8 days) and the later stage (12-47 days or 10-47 days). In accordance with the analysis of ion source, it is comprehensively judged that the cation exchange reaction is the main reaction in the early stage of water-rock interaction in this test, with the ion change mainly manifested in the sharp increase of Na+ concentration and the sharp decrease of Ca2+ concentration. In the middle stage, cation exchange reaction and mineral dissolution-precipitation are dominated, with the ion changes mainly manifested in the increase of Na+, K+ and Cl? concentration, the decrease of Ca2+, HCO₃? and Mg2+ concentration, the increase of SO₄ 2? concentration in S-K group, and the decrease of SO₄ 2?concentration in N-K group. In the later stage, the water-rock interaction is weak in a dynamic equilibrium state, without any obvious change in the concentration of each ion. Moreover, the rock properties have a certain influence on ion changes. Generally, the research results could provide a theoretical reference for the purification mechanism of mine water in different operating periods of coal mine underground reservoirs.