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In order to find out the chemical characteristics and causes of groundwater in Yuanyanghu Mining Area, and to provide basis for the prevention and control of water disaster in the mining area, the aquifer hydro-chemistry of Quaternary, Cretaceous, Zhiluo Formation, 2#-6# coal seams, 6#-18# coal seams and below 18# coal seam in the mining area was analyzed. The results show that K++Na+ is the main cation, and SO42- and Cl- are the main anions, and these four ions are the main sources of TDS. Groundwater in Quaternary aquifer is mainly controlled by weathering and leaching of rocks and minerals, while groundwater samples of other aquifers are basically affected by evaporation and concertration to varying degrees. According to the chlor-alkali index of groundwater, cationic adsorption exists in different degrees in all aquifers. The chlor-alkali index decreases gradually from the deep aquifer below 18# coal seam to the shallow Quaternary aquifer, and the alternating cation adsorption is strengthened, and the contents of Ca2+ and Mg2+ decrease continuously. The groundwater of each aquifer is affected by desulphurization acid in different degrees. According to ion ratio analysis, the hydrochemical compostion of each aquifer mainly comes from the dissolution of rock salt, among which Ca2+ and Mg2+ come from the dissolution of silicate and evaporite. From isotope analysis, it can be found that Quaternary groundwater is mainly supplied by precititation, and evaporation leads to enrichment of heavy isotopes in groundwater of Zhiluo Fromation and Yan’an Fromation between 2#-6# coal seams, and there are different degrees of mutual transformation among aquifers, and they are supplied by other aquifers.

This study investigated the effects of reaction temperature (300–360 °C), reaction time (0–60 min), and the ratio of raw materials to solvent (1:5–1:15; g/mL) on the HydroThermal Liquefaction (HTL) of Chinese Herb Residues (CHR) for Bio-Oil (BO) production. Optimal HTL conditions for CHR were determined. To enhance both the yield and quality of BO, metal-modified catalysts including Fe/MCM-41, Co/MCM-41, and Ni/MCM-41 were prepared. These catalysts, after hydrogen reduction, loaded metal elements in their elemental state onto the carrier. Subsequently, CHR catalytic HTL experiments were conducted at 330 °C for 15 min with a ratio of 1:10 (g/mL). BO analysis was performed using EA, GC-MS, and FT-IR. Under the optimal HTL conditions (330 °C/15 min/1:10), the BO yield reached 24.57 wt.%, with a Higher Heating Value (HHV) of 25.96 MJ/kg. The major components of the BO included phenols, ketones, acids, and esters. In the catalytic HTL, Fe/MCM-41 (26.15 wt.%), Ni/MCM-41 (26.2 wt.%), and Co/MCM-41 (27.05 wt.%) catalysts each achieved higher BO yields. When using Ni/MCM-41 catalyst, the highest HHV of BO reached 32.01 MJ/kg, representing an 81% improvement over CHR HHV of 17.66 MJ/kg. Additionally, with Fe/MCM-41 catalyst, the lowest oxygen content in BO was 9.68%, and the selectivity for phenols and ketones was the highest, showing increases of 15.22% and 33.15%, respectively, reaching 44.13% and 24.5%. The results indicate that HTL can effectively convert high-moisture CHR into valuable products. Hydrogen-reduced metal-modified catalysts contribute significantly to increasing BO yield, promoting deoxygenation and hydrogenation reactions, and markedly improving HHV and the selectivity of chemical components, thereby effectively enhancing both the yield and quality of BO.

In order to effectively control the water flow from the overburden of the heading roadway, the method of drainage and depressurization combined with intermittent repeated grouting was adopted to transfrom the broken sandstone zone of the heading roadway. Through drilling long distance directional borehole above the roadway, the water-riched area can be drainaged. The layout of grouting boreholes on the plane and vertical was designed, and different grouting orifice devices are used for borehole with different water flow. Long distance directional boreholes were used for drainage grouting, and intermittent circular grouting was used for conventional borehole. The effect of fracture grouting in sandstone was verified by coring test and water inflow observation. It is illustrated by examples that the grouting effect of complete sandstone is poor, while the grouting effect of sandstone with developed fissures is good. The purpose of reducing water inflow of heading roadway and strengthening the broken surrounding rock can be realized by drainage water with borehole to reduce groundwater pressure in local area and sealing the fissures with grouting.

In order to avoid the water disaster of fault and sandstone below the coal seam, it is necessary to master the conductivity of fault accurately. Through the dewatering test with large drawdown and water flow of Baotashan sandstone aquifer in the bottom of Yan’an Formation, the good conductivity of DF20 fault in vertical was found out, and the DF20 fault is an important hydraulic connection channel of each aquifer. It is clear that DF20 and F2 fault have hydraulic connection in horizontal direction, and Triassic aquifer has the hydraulic connetion with Baotashan sandstone aquifer by DF20 and F2 faults. It is proposed that the intersection of DF20 and FD5 faults has the strongest conductivity and is the main location of water exchange of each aquifer. The conductivity of DF20 fault is not uniform in the horizontal direction. The conductivity of DF20 fault located in the middle of the coal field is weak, while the conductivity of DF20 fault in the south of the coal field is strong. The results show that the hydrogeological parameters of the fault not only can be obtained through the pumping test and dewatering test, but also the hydrogeological conductivity and spatial characteristics of the fault can be found out.

In order to find out the hydraulic connection between Baotashan sandstone aquifer from the floor of coal seam and other aquifers in the Jurassic coalfield, the underground dewatering test is adopted. The Baotashan sandstone aquifer is drained with large water flow, and the groundwater levels of other aquifers are observed by long-time observation boreholes synchronously. According to the response of different aquifers water level to the dewatering process from Baotashan sandstone aquifer, it is determined that the cretaceous aquifer, aquifer between the coal seams and triassic aquifer have obvious hydraulic connection with Baotashan sandstone aquifer. According to the vertical and plane characteristics of groundwater hydrochemistry of each aquifer, it is considered that the Baotashan sandstone aquifer in the west of the coalfield has positive alternation and good runoff condition, and DF20 fault is the hydraulic connection channel between the Baotashan sandstone aquifer and other aquifers. Based on the analysis of the groundwater flow field of each aquifer, it is determined that the Baotashan sandstone aquifer and cretaceous aquifer feed the aquifer between the coal seam through DF20 fault.