Coalfields In China Research Articles

Floor failure behavior and water disaster prevention system of ultra-wide opposite pulling working face mining on confined aquifer

The floor failure depth of the ultra-wide opposite pulling working face (OPWF) mining on the confined aquifer is larger, and the risk of water inrush is higher. Based on the engineering background of Binhu Coal Mine (BHCM) in North China Coalfield, this paper analyzes the distribution rule of floor support pressure in OPWF mining, carries out numerical simulation before and after roof cutting, and microseismic-electrical joint dynamic monitoring. The results show that the failure depth, vertical stress, maximum principal stress, maximum shear stress, and pore water pressure of floor after roof cutting are decreased by 28.6 %, 15.5 %, 12.1 %, 30.9 %, and 41.7 %, respectively, the stress concentration coefficient is also decreased by 19.5 %. Roof cutting blocks the propagation path of mining stress, reduces the mine pressure concentration and controls the floor failure depth. Using the optimal univariate function between the floor failure depth and mining width, mining depth, mining height, roof cutting height, working face stagger distance, a multi-factor prediction model for the floor failure depth of the OPWF mining is established, and the accuracy of the model is more than 90 %. Combined with the methods of exploration, treatment, and monitoring, the water disaster prevention technical guarantee system in the ultra-wide OPWF mining on the confined aquifer is constructed, which provides a new method for the prevention and control of floor water disasters during mining.

Study on precursor information and disaster mechanism of sudden change of seepage in mining rock mass

Abstract Changes in the stress field and seepage field of mining unloading are one of the important causes of deformation and destabilization of the rock body of the bottom slab. With the increase of mining intensity and depth, the disaster of water influx on the bottom plate under the dual action of mining unloading and pressurized water has become one of the main problems restricting the efficient and safe mining of coal. Based on the research background of confined water inrush from Ordovician limestone floor in North China Coalfield, the numerical analysis revealed that mining unloading concentrates stresses, increases deformation, and increases the plastic zone and permeability range. Based on laboratory acoustic emission and mechanical tests, it is found that the peak of acoustic emission ringing number can be one of the precursor information of limestone seepage mutation. This study reveals the evolution law of rock body deformation and permeability under the unloading path, and the research obtains the unloading seepage and water gushing disaster mechanism of the subgrade rock body.

Investigation on water inrush fracture mechanics model based on fracture mechanics and microseismic monitoring

North China coalfield is one of the most severe coal fields threatened by Ordovician limestone water (buried depth exceeding 1000 m). In this paper, the hydraulic mechanism of Ordovician limestone water in the complex geological structure are studied. An interesting phenomenon was found in the study, the water inrush from Ordovician limestone has a “latent period” and presents lag water inrush law. The hydrochemical characteristics of the early stage in Xingdong coal mine is non-Ordovician limestone water chemical characteristics, the later stage gradually shows the Ordovician limestone water with the continuous outflow. Meanwhile, the hyperbolic contour distribution characteristics are also observed in the spatial distribution law of microseismic in the floor working face. The minimum damage area is in the layer at the hyperbolic apex, which is the critical breakthrough point of water inrush. Furthermore, the water inrush fracture mechanics model (WIFM) of concealed fault with high confined water is established based on the fracture mechanics theory. The results show that the critical values of the length and angle of the water inrush of the conceal fault are about 50 m and 40°. It should be pointed out that the longer and larger angle conceal faults indicate the longer of the fracture expansion at the tip of the fault, and the probability of water inrush increases. Special attention should be paid to such concealed faults and methods such as grouting should be adopted to avoid the water inrush disaster caused by the activation of faults. This model provides a theoretical basis for the mechanical mechanism of the coal seam floor water inrush process.

Electrically conductive coals in nature: Their traits, whereabouts, green-exploitations and impacts

Amid the global advocation of carbon-neutrality, high-carbon-footprint-combustion is still catastrophically depleting the natural coal-reserves. Parallelly, high-value graphitic nanomaterials, from low-end graphitic-nano-grains known as carbon black to high-end polymorphs of carbon nanofiber, carbon nanotube and graphene, have been invented to fuel an emerging economy with innovations emphasizing profitability instead of sustainability. Here, by analyzing the coal-traits and the relevant geological metamorphisms, we adopt the portrait of coal as a carbonaceous composite comprising graphitic nano-grains, typically merely 1–2 nm in size and not more than 20 % in concentration, in a matrix of amorphous carbonaceous macromolecules high in aromaticity, dusted by mineral-specks, with weak intermolecular links among all constituents. At the proximity of geological faults, metamorphism, carbonization and graphitization were once accelerated to form more graphitic nano-grains with crystallinity and electrical conductivity enhanced. Thus, coal-seams near such fault-dikes likely have electrically conductive coals full of percolated graphitic nano-grains with weak grain-boundary-links such that coal can be comminuted to graphitic nanomaterials without any chemical etch, with little loss, low cost and minimal environmental-load. Empowered by these views, we have found over twenty coal-fields in China and many more elsewhere having such conductive coals, with trials from lattice-imaging characterization to ton-scale production to validate our predictions. We trust that sharing such concepts and experimental findings promises new vehicles embracing sustainability to vitalize the coal-industry.

Modeling of Supercritical CO2 Adsorption for Low-Permeability Coal Seam of Huainan-Huaibei Coalfield, China.

Investigating the coal adsorption behavior on supercritical CO2 (ScCO2) is crucial for long-term CO2 geological storage. In this paper, low-permeability coal samples from the Huainan-Huaibei coalfields in China were selected. The high-pressure isothermal adsorption of CO2 was carried out at 36, 42, and 48 °C. The results of adsorption experiments were analyzed by fitting 9 types of modified adsorption models, including three different adsorption theories. Considering that different adsorption mechanisms may exist for CO2 in coal, 14 mixed adsorption models were established. The accuracy of the coefficient of determination (R2) and root-mean-square error (RMSE) for ScCO2 excess adsorption capacity was analyzed, mainly focusing on the accuracy of the key model parameters such as the adsorption phase density and the theoretical adsorption capacity. These parameters were discussed, combined with the predicted adsorption phase density of CO2 based on the intercept method. The results indicate that among the 9 types of modified adsorption considered, based on the adsorption phase density screening, the deviation of the predicted adsorption capacity from the experimental value was then considered. The Dubinin-Radushkevich (DR) model can effectively fit the adsorption behavior of CO2 at low pressure (<7.5 MPa). The Langmuir (L), Langmuir-Freundlich (LF), Extended-Langmuir (EL), and TOTH models can effectively fit the adsorption behavior of CO2 at high pressure (7.5-20 MPa), while the multimolecular layer models were unsuitable for fitting ScCO2 adsorption. The model fitting results showed that only the monomolecular layer and micropore-filled adsorption models were suitable for fitting the ScCO2 adsorption capacity. The DR-LF model best fits the adsorption data based on its key parameters of adsorption phase density and theoretical adsorption capacity. The established mixed model DR-LF fitting results showed that the CO2 in coal was dominated by microporous filling adsorption. The higher the temperature, the greater the contribution of microporous filling adsorption to the total adsorption. There still exists deviation in the adsorption phase density and theoretical adsorption capacity. The contribution percentage of different adsorption mechanisms of CO2 in coal needs to be further investigated.

3D Reconstruction of Pore and Fracture Structures in Crushed Soft Coal with Low Permeability and Its Permeability Analysis: Implications for the Design of CO2 Injection and CH4 Production.

In order to improve the CO2 injection and CH4 production efficiencies during the CO2-ECBM process, it is necessary to clarify the relationship among the complexity of pore and fracture structures, the typicality of the fluid migration path, and the heterogeneity of reservoir permeability. In this study, crushed soft coal with low permeability from Huainan and Huaibei coalfields of China was taken as the research object. First, the three-dimensional (3D) visualization reconstruction of pore and fracture structures was realized. Second, the equivalent pore and fracture network model was constructed. Finally, the permeability evolution and its anisotropy of the coal reservoir were dynamically demonstrated. In this study, the implication of surface porosity on the heterogeneity of pore and fracture structures was first discussed, followed by the implication of coordination number on the anisotropy of fluid flow, and finally, the influence of the anisotropy of fluid flow on the CO2-ECBM process was discussed. The results show that the equivalent pore and fracture network models of the reservoir structure can be constructed based on the digital rock physics technology. The analysis results of porosity, interconnected porosity, typical path of fluid migration, absolute permeability, and surface porosity of each sample have good consistency in characterizing the complexity of pore and fracture structures and the heterogeneity of permeability. The average coordination numbers of RL and LZ samples are 5.99 and 5.78, respectively, and the number of pores and throats is well-balanced, which indicates that LZ and RL collieries are suitable for the development of CO2-ECBM industrial tests. When the interconnected pores and fractures are mainly developed vertically and horizontally, the construction of drilling technology of the CO2-ECBM process should be mainly designed for vertical wells and horizontal wells, respectively. This study has important theoretical and practical significance for the industrial testing and commercialization of CO2-ECBM technology in crushed soft coal with low permeability.

Geochemical characteristics and migration patterns of rare earth elements in coal mining subsidence lakes under the influence of multiple factors

Mining activities cause surface subsidence and the formation of subsidence lakes, which dynamically change with the continuous coal mining activities. Under the combined influence of various human activities such as agriculture, aquaculture, and floating photovoltaic (FPV), the lake environment undergoes continuous changes, thereby altering the geochemical characteristics of rare earth elements (REEs) in the sediment. This study focused on the subsidence lakes in the Huainan coalfield in eastern China to examine the REEs content in the sediment, elucidated the temporal variations and geochemical characteristics of REEs distribution, explored the main controlling factors of REEs in the sediment, and revealed the migration and transformation behavior of REEs during dynamic subsidence processes. The study revealed that the migration pattern of REEs in the sediment was closely related to the duration of subsidence. The average content of REEs in lake sediments with subsidence duration <5 years increased from 219 μg·g−1 to 248 μg·g−1 compared to the soil, showing an enrichment model primarily driven by rainwater runoff, groundwater input retention, and mineral dissolution. With further subsidence, the processes of reduction dissolution of Fe–Mn oxides/hydroxides, organic colloid adsorption, and hydraulic disturbance gradually replaced the aforementioned enrichment behavior as the main migration pathways, resulting in a decrease in the average REEs content in the sediment to 179 μg·g−1 for subsidence durations exceeding 10 years. There was no strong correlation between REEs fractionation and subsidence duration. Artificial activities, such as FPV, are important factors causing Cerium and Erbium anomalies in some subsidence lake sediments. This study was not only of significant importance for understanding the migration, distribution, and environmental behavior of pollutants in aquatic environments under the interference of human activities but also provided a solid theoretical foundation for the future management of coal mining subsidence lakes.

A new insight of water inrush mode and coal (rock) pillars setting in near-fault mining under high confined water

Mining-induced fault water inrush has become the most critical disaster-causing factor of mine water disasters in mines in recent years. In near-fault coal mining, the water flowing fractures caused by mining in the roof (floor) of a coal seam may connect the fault fracture zone and induce fault water inrush. The most effective way to prevent fault water damage is to set waterproof coal (rock) pillars. However, the width of coal (rock) pillars was mainly calculated by empirical formulas in the past, and the calculated results were quite different from the actual ones. This paper determines the safe water blocking zone and inelastic zone by introducing mine pressure and confined water pressure (“double pressure”). Then, the range of the mine pressure failure zone is determined by comprehensively considering the floor strata's peak stress propagation direction and the roof strata's collapse propagation angle. The hydraulic model of roof (floor) water inrush in near-fault coal mining under “double pressure” control is established. A new method for calculating the width of waterproof coal (rock) pillars in coal mining on large normal faults is derived by considering the nature of the fault, mine pressure, and confined water pressure. Finally, the research results are applied to the width calculation of waterproof coal (rock) pillars in the Jiaxiang branch fault of Xinhe Coal Mine, and the FLAC3D software is used to conduct numerical simulation and check the calculation of the pillars' width of coal (rock) under the influence of mining. The formation mode of fracture channels in the roof (floor) of a coal seam in near-fault mining is proposed, and the failure theory of surrounding rock in near-fault mining is perfected. The research results will effectively guide the layout of the near-fault working face on the Ordovician limestone confined aquifer in North China Coalfield, liberate a large number of resources threatened by fault water damage, and provide a theoretical basis for the prevention and control of mine fault water damage under other similar geological conditions.

An improved model to predict the water-inrush risk under an unconsolidated confined aquifer based on analytic hierarchy process and information value method

To prevent water inrush hazards of mining under the Quaternary unconsolidated confined aquifer in North China coalfield, it is necessary to build a water inrush prediction model to guarantee coal safety production. The current method of evaluating mining hazards under unconsolidated confined aquifers is easy to fall into the problems of simple superposition of evaluation factors, large subjectivity of the factor selection, and low accuracy of prediction results. In this paper, an analytic hierarchy process (AHP) is improved according to contribution of information value method (IVM) to analyze the impact of water inrush factors. The factor weight values are considered in calculating the total information value of IVM to build a coupled AHP-IVM model. The information value of each factor is calculated through IVM, and area under curve (AUC) value is used to rank the factors, to exclude the subjective judgment of the importance of each factor. The geological and hydrogeological data of Qinan coal mine in Huaibei coalfield are analyzed and organized. The results suggest that the coupled AHP-IVM model has an AUC value of 0.8309, indicating its great potential and practical significance for future mining operations.

Pore structure characteristics of shale in coal-bearing strata: In the case of the Shanxi formation of lower Permian in Huainan coalfield in China

Reservoir pore characteristics are an important part of shale gas reservoir capacity evaluation. Compared with Marine shale, the study of coal measure shale is relatively backward in China. In order to deeply analyze the reservoir properties of coal measure shale gas and give priority to favorable reservoirs, the pore structure characteristics of shale in coal measures from the Shanxi Formation of Lower Permian in Huainan Coalfield of China were investigated in this study. The pore size distribution, specific surface area (SSA), and pore volume (PV) were obtained. The BET surface area and PVs are inconsistent with the variability in total organic content (TOC) and composition of the samples. There are unobvious negative correlations between PV, SSA, and TOC for the samples in this study. However, the contribution of clay minerals to PV and SSA seems to be positive, especially for the mixed-layer minerals of illite and smectite.

Study on Prevention and Control of Confined Water Hazard in Deep Resource Exploitation: Scientific Basis of “GCD-D” Design

Deep mining of resources has destroyed the stress balance of original rock, formed water gushing channel, and caused the outburst of confined water, thus causing disaster. At present, “Ground Controlled Directional Bedding Branch Drilling (GCD-D)” grouting has achieved remarkable results in controlling water disasters. However, “what is the scientific design principle of GCD-D?” This key scientific question has not yet been answered by systematic science. According to the regional engineering geology and hydrogeological conditions of North China-type coalfields, this study uses the methods of analogy, theoretical analysis, and model analysis to demonstrate and analyze and obtains six basic principles for the selection of the target layer for the layout of “GCD-D.” The design principle of “GCD-D” was put forward for the first time. The results can provide a scientific theoretical basis for the control of confined water disaster in deep mining of North China coalfields.

Study on Tensile Strength and Damage Evolution Law of Sandy Mudstones with Different Sedimentary Ages in Dongsheng Coalfield in China

Sandy mudstones of various sedimentary ages are deposited in the Dongsheng Coalfield in China. Studying the tensile mechanical properties of these sandy mudstones would provide a reference for underground construction in this area. Four sets of sandy mudstones with different sedimentary ages from Dongsheng Coalfield in China were selected as the research objects. First, the mineral composition and microstructure of the 4 sets of Brazilian disc specimens were obtained by X-ray diffraction and scanning electron microscope. With the increase of sedimentary age, the microstructure of sandy mudstone becomes denser. Then the deformation and acoustic emission (AE) characteristics of the specimens during the Brazilian tests were observed. The indirect tensile strength, peak strain, total strain and pre-peak energy accumulation of sandy mudstones showed an approximate increasing trend with sedimentary age increasing. AE hit rate of the specimens with longer sedimentary age was higher, and the AE signals of these specimens with longer sedimentary age were released more severely after the peak tensile strength. The influence of sedimentary age on the properties of sandy mudstones was discussed from three aspects: the main mineral components, the geostress environment of sandy mudstone, microscopic morphology and granular structure.

Research into the Mechanism and Application of Liquid CO2 Phase-Transition Fracturing in a Coal Seam to Enhance Permeability

The geological structures of the coal fields in China are complex. With a continuous increase in the mining depth, the coal seams show the characteristics of high gas and low permeability, and the disaster potential for a coal and gas outburst intensifies in the process of coal mining. Gas drainage is one of the primary measures used to prevent and control gas disasters. Effectively improving the permeability of a coal seam requires urgent attention. Currently, the method of loose blasting is used in engineering to enhance the permeability of coal seams. However, the technology of loose blasting easily leads to the poor development of coal fractures or the severe crushing of coal, which will affect the gas drainage. Thus, this paper studied the technology of liquid CO2 phase-transition fracturing in a coal seam. COMSOL was used to determine the influence radius of the liquid carbon-dioxide phase-transition cracking, which was 13.4 m, and to design the scheme of the borehole. The field test was carried out in the 81,506th working face of the Baode Coal Mine. From the onsite-monitoring data, the results showed that the drainage effect increased by 293.9%, the gas-drainage concentration increased by 242.4%, the permeability coefficient of the coal seam increased by 3–7.75 times, and the permeability enhancement effect was good.

Effects of Ground Subsidence on Vegetation Chlorophyll Content in Semi-Arid Mining Area: From Leaf Scale to Canopy Scale.

Ground subsidence is the main cause of vegetation degradation in mining areas. It is of great significance to study the effects of ground subsidence on vegetation. At present, few studies have analyzed the effects of ground subsidence on vegetation from different scales. However, the conclusions on different scales may differ. In this experiment, chlorophyll content was used as an indicator of vegetation degradation. We conducted a long-term field survey in the Lijiahao coalfield in China. Based on field survey data and remote sensing images, we analyzed the effects of ground subsidence on chlorophyll content from two scales (leaf scale and canopy scale) and summarized the similarities and differences. We found that, regardless of leaf scale or canopy scale, the effects of subsidence on chlorophyll content have the following three characteristics: (1) mining had the least effect on chlorophyll content in the neutral area, followed by the compression area, and the greatest effect on chlorophyll content in the extension area; (2) subsidence had a slight effect on chlorophyll content of Caragana korshins, but a serious effect on chlorophyll content of Stipa baicalensis; (3) chlorophyll content was not immediately affected when the ground sank. It was the cumulative subsidence that affects chlorophyll content. The difference between leaf scale and canopy scale was that the chlorophyll content at canopy scale is more affected by mining. This means that when assessing vegetation degradation, the results obtained by remote sensing were more severe than those measured in the field. We believe that this is because the canopy chlorophyll content obtained by remote sensing is also affected by the plant canopy structure. We recommend that mining and ecological restoration should be carried out concurrently, and that ground fissures should be taken as the focus of ecological restoration. In addition, Caragana korshins ought to be widely planted. Most importantly, managers should assess the effects of ground subsidence on vegetation on different scales. However, managers need to be aware of differences at different scales.

A method for predicting the water-flowing fractured zone height based on an improved key stratum theory

In the process of using the original key stratum theory to predict the height of a water-flowing fractured zone (WFZ), the influence of rock strata outside the calculation range on the rock strata within the calculation range as well as the fact that the shape of the overburden deformation area will change with the excavation length are ignored. In this paper, an improved key stratum theory (IKS theory) was proposed by fixing these two shortcomings. Then, a WFZ height prediction method based on IKS theory was established and applied. First, the range of overburden involved in the analysis was determined according to the tensile stress distribution range above the goaf. Second, the key stratum in the overburden involved in the analysis was identified through IKS theory. Finally, the tendency of the WFZ to develop upward was determined by judging whether or not the identified key stratum will break. The proposed method was applied and verified in a mining case study, and the reasons for the differences in the development patterns between the WFZs in coalfields in Northwest and East China were also fully explained by this method.

Analysis of Overburden Deformation and Migration under Huge Thick Unconsolidated Layers Based on Multiple Approaches

Underground mining safety risk increases with the more complicated geological conditions in deep strata, so coal mines turn to the upper limit mining of shallow coal seams under the Cenozoic strata. Nevertheless, coal mines in the Northern China coalfield are mainly covered by thicker loose sandy layers with more abundant water. The analysis of overburdened strata deformation properties is essential for safe, efficient, and environmentally friendly production. This paper discusses the deformation and migration of overburdened strata through mechanical analysis, numerical and physical similar simulations, and in situ field measurement. A thorough understanding of overburdened strata deformation induced by mining has been obtained, and the results are as follows: The immediate roof first collapses to form the caved zone accompanied by the first weighting, and the fractured zone and bending deformation zone begin to develop in sequence; the separation layer is observed during the period of fracture development. However, the occurrence of the bending deformation subsidence results in the closure of the separation space; the ratio of fractured and mining height is quantified to 14.4:1.0 by the comparative analysis. The results may serve as technical evidence to support the mining safety of the study area and other coal mines with similar geological conditions.

Comparative Analysis of the Drainage Effect Based on Improved Hydraulic Flushing Technology.

The composite structure coal seam composed of coal seams with strong and weak deformation is widely developed in the coalfields in Southwest and North China. The implementation of hydraulic flushing in soft coal stratification can effectively relieve the pressure and increase the permeability of coal seams, so it can improve the effect of underground gas drainage. Taking Xin'an Coal Mine, West Henan province, China, as an example, this paper discussed the influence of hydraulic flushing on the gas drainage effect in soft coal seam by means of field investigation, numerical simulation analysis, similar simulation, and field verification. As the same time, a fluid-solid coupling model of gas drainage based on layered hydraulic flushing technology is established, and the differences and reasons of the gas drainage effect after layered hydraulic flushing in soft and hard composite coal seams are discussed. The results show that (1) the gas concentration change of layered flushing boreholes intermittently rises rapidly, and there is no obvious law, while that of conventional flushing boreholes shows a regular attenuation trend. (2) According to the numerical simulation results, after 30 days of drainage, the effective drainage range of layered hydraulic flushing is 8.33 m3 higher than that of conventional hydraulic flushing. (3) There are not a few points where the single borehole concentration data of each row of layered flushing boreholes are in the high level. Meanwhile, the maximum concentration of all conventional flushing boreholes is less than 40%, except that one borehole can reach 70% at the beginning. (4) All of the average gas drainage concentration of single-row boreholes using layered flushing technology is greater than 20% in the vast majority of days, while that of the conventional flushing boreholes is only higher than 20% in row 5 and has only lasted for 2 days. The difference of the drainage effect is obvious.

Analysis of Jet Structure and Physical Properties in the Coalfields of Northern China

Archeological discoveries have identified China as one of the first countries in the world to use jet. However, many differences are evident between the jet currently found in existing mines and the archaeological discoveries of cultural relics in terms of texture and quality according to the definition of organic gem jet in gemology. This paper reports the results of microscopic analysis and coal quality analysis of the coal and jet samples from coal seams in Fushun Open-pit Mine and Datong Coalfield. The findings reveal that the physical and chemical composition of coal in different mining areas differs markedly. However, the differences between jet and coal in both mining areas are similar; that is, jet has lighter density and greater hardness (2–4) compared to coal, as well as elasticity (engravability), and both jet and coal occur in the (rock slurry) hydrothermal environment. Lastly, the analysis shows that the formation of jet depends on rubber-like hydrocarbon coal with a high degree of corruption in a sedimentary environment under the vulcanization of a hydrothermal, high-sulfur environment.

Pyrolytic stage evolution mechanism of Zhundong coal based on reaction consistency analysis of mono/multi molecular models

Zhundong coalfield is the largest coalfield in China and the unclear stage evolution mechanism of Zhundong coal pyrolysis is the key factor restricting its coal fire control. Here, the monomolecular model (299 atoms) and large-scale multimolecular model (5083 atoms) were constructed for Liu huanggou (LHG) coal from Zhundong coalfield. The pyrolysis processes of the two models were calculated by ReaxFF MD method. Based on the reaction consistency analysis, the reaction paths tracing on pyrolysis stage evolution and toxic gases formation mechanisms were obtained. The LHG coal pyrolysis process is mainly because of the breakages of the ether oxygen bridge bonds, thioether bridge bonds and aliphatic hydrocarbon bridge bonds. It begins with the shedding of small molecules and then undergoes the thermal decomposition of the main structure and pyrolytic fragments. During the pyrolysis process, the LHG coal has constantly broken out tars, gases and other key products, accompanied by a large number of free radicals and intermediates produced. The main sources of CO are the active reaction sites where the carbonyl group and the carboxyl group located; H2S is directly produced from the sulfhydryl group. The research results will guide the staged control and directional transformation of coal fire.

Study on water inrush pattern of Ordovician limestone in North China Coalfield based on hydrochemical characteristics and evolution processes: A case study in Binhu and Wangchao Coal Mine of Shandong Province, China

Groundwater plays a critical role in the mining areas, providing water for human activities and the growth of animals and plants, but also the main object of mine water disaster prevention. A study on hydrochemical characteristics and evolution in the process of mine water inrush has important practical significance for accurately identifying mine water inrush sources. In this study, the water samples of Ordovician limestone water, the 14th limestone water, and inrush water in Binhu and Wangchao Coal Mines of Tengxian Coalfield were collected. The water samples were compared and analyzed to reveal the variation characteristics of major ion concentration and hydrochemical evolution mechanism during floor cracking-Ordovician limestone water inrush. The results indicated that the type of Ordovician limestone water is Cl-Ca type, the 14th limestone water is Mixed type, and all inrush water is Cl-Na type. Na+(K+) is negative with Ca2+ and Mg2+, while Ca2+ is positive with Mg2+. Hydrochemical analysis showed that the degrees of cation exchange in groundwater are inrush water > the 14th limestone water > Ordovician limestone water, and the average cation exchange contents △C(K++Na+) c are 30.85 meq/L, 9.90 meq/L, and 8.10 meq/L, respectively. Cation exchange significantly changed the Ca2+(Mg2+) and Na+(K+) levels in an aqueous solution during water inrush from Ordovician limestone. The concentration of Ca2+(Mg2+) decreased, while the concentration of Na+(K+) increased significantly and finally formed inrush water with high Na+(K+) and low Ca2+(Mg2+) levels. The saturation index (SI) indicated that the minerals CaCO3, CaMg(CO3)2, and CaSO4.H2O are in oversaturation, the cation exchange results in the decreasing Ca2+(Mg2+), and the SI value is limestone water > the 14th limestone water > inrush water. The cluster analysis (CA) results also showed that considering the effect of cation exchange on the ions concentration of groundwater, the Ordovician limestone, the 14th limestone water, and inrush water samples have the same source in the study area. Overall, The cation exchange significantly affects groundwater ion concentration in the process of Ordovician limestone water inrush. These findings provide a new insight into the hydrochemical evolution mechanism of groundwater and reveal the evolution pattern of Ordovician limestone water inrush in the North China Coalfield.