As an important industrial by-product produced in the process of coal-fired power generation, fly ash shows great potential in CO₂ mineralization. In order to solve the problem of low efficiency of direct mineralization of CO₂ by fly ash, N-methyldiethanolamine (MDEA)/diisopropanolamine (DIPA) mixed amine solution was used to absorb CO₂ to improve the subsequent CO₂ fixation efficiency. The effects of different MDEA/DIPA ratio, solid-liquid ratio, reaction temperature and reaction time on CO₂ absorption and mineralization efficiency were systematically analyzed. The results show that the performance of MDEA/DIPA mixed amine solution is better than that of monoamine solution. When the MDEA∶DIPA is 1∶3, the solid-liquid ratio is 270 g/L, the reaction temperature is 45 ℃, and the reaction time is not less than 30 min, the CO₂ loading is the highest, which is 1.66 mol/L, and the mineralization efficiency is 45.2%. The results of FTIR, XRD and TG analysis show that MDEA/DIPA mixed amine solution mainly contained , , protonated MDEA/DIPA and carbamate. Compared with the original fly ash sample, the content of CaCO₃ in the solid product increased significantly, and mainly existed in the form of calcite. MDEA/DIPA mixed amine solution and fly ash combine CO₂ absorption and mineralization, which provides a reference for CO₂ storage and fly ash waste treatment.

To reveal the mechanical response law of filling body in deep stope under high ground stress and mining disturbance, the stope of the eighth middle section of Jiaojia Gold Mine was selected as the research object. The stress and deformation data of filling body in different mining stages were obtained by setting pressure cells and settlement sensor. The three-dimensional numerical model of filling body in deep stope was established, and the stress redistribution and deformation evolution law of filling body under multi-layer mining conditions were obtained. The results show that the stress of the filling body fluctuates periodically in the process of mining disturbance. The maximum stress fluctuation in the blasting stage is about 0.02 MPa, and the filling body is mainly elastic strain. During the mining process, the stress of the internal measuring points of the filling body is generally higher than that of the peripheral measuring points, and the vertical stress increases the most. The numerical simulation results show that the interlayer stress transfer characteristics are obvious, and the overall layer-by-layer transfer law from top to bottom is presented. The deformation of the filling body is relatively concentrated and large in the early stage of bearing, and tends to be stable in the later stage. The research results can provide theoretical basis and technical reference for the design of filling body and stability control of stope in deep gold mine.

Blasting damage of surrounding rock is recognized as one of the key factors inducing roadway instability. For the roadways in Jinfeng Gold Mine with a burial depth of over 800 m, a numerical model of full-section blasting excavation was established by means of ANSYS/LS-DYNA, and five rounds of simulation calculations for full-section blasting excavation were carried out. Four typical positions were selected on the roadway section to analyze the cumulative damage effect of multiple blasting events on the surrounding rock. Based on the distribution characteristics of surrounding rock damage, a support method consisting of surrounding rock grouting+long anchor bolts+metal mesh+shotcrete was proposed, and its field application was carried out. The results show that in a single full-section blasting excavation, the blasting vibration from the first two blasting stages causes the expansion of the surrounding rock damage zone, which in turn leads to an accelerated increase in the displacement and damage of the surrounding rock during the last two blasting stages. During multiple full-section blasting excavations, existing damage zones invade the rock mass to be excavated in subsequent blasting operations. The new and existing damage zones connect and coalesce, and their expansion is accelerated, with the scope of the new damage zones increasing by approximately 20% compared with that of the previous blasting round. After the optimization of the support scheme, the reduction rates of convergence displacement of the roadway roof and floor and its two sidewalls reach 41.37% and 42.03% respectively. Anchor pull-out tests indicate that the anchor displacement of the new support scheme is reduced by 37.2% compared with that of the original support scheme, and the anchor rebound coefficient is significantly improved. This study can provide a reference for the calculation of surrounding rock damage and support design in excavation blasting of deep high-stress roadways.

Among the rock mass weakening technology, gas fracturing is more likely to form complex fracture networks compared with hydraulic fracturing. In order to study the fracture propagation mechanism of gas fracturing in the field of directional fracturing technology, laboratory physical experiments and numerical simulation studies on directional gas fracturing based on the radial guide groove technology were carried out. A preparation method of radial guide groove was proposed, a special sealing fixture was designed to simulate the principle of packer, and the acoustic emission device was used to monitor the gas fracturing process in real time. The experimental results show that the radial guide groove can obviously change the propagation direction of gas fracturing fractures within a certain scale, and the fracture initiation pressure is reduced by about 30% compared with that without guide groove. Under the dynamic loading method of gas fracturing, a unique fracture network of primary fracture and secondary micro-fracture appears, and the fracture width increases by 2-3 times compared with the quasi-static loading method. On this basis, LS-DYNA was used to simulate the dynamic dynamics of transient gas fracturing with or without guide groove. Indicators such as effective plastic strain and von mises stress of the models with and without radial guide grooves were compared and analyzed, and the simulation results are consistent with the laboratory experimental results. The research results can promote the development of directional fracturing technology and rock mass weakening methods for deep hard rocks, and provide technical support for the engineering application of directional gas fracturing technology.

In view of the following mining technical challenges in underground mine operations: some stopes are laid out within the broken oxidation zone, giving rise to roof caving and sidewall collapse during production, in addition, ore caving trenches are reserved at the bottom of sublevel medium-deep hole stopes to facilitate ore drawing, which results in the failure of effective recovery of the triangular ore pillars at the stope bottom after mining completion due to the poor quality of backfill materials, thus causing enormous waste of mineral resources. A polymetallic mine was selected as the research object, through field investigation, theoretical analysis and reference to the experience of similar mines, a combined support scheme of shotcrete-bolt-mesh with long anchor cable grouting was proposed to pre-reinforce the roof of the stope to ensure the safe mining of ore in the range of broken oxidation zone. Meanwhile, the medium-deep hole blasting technology was optimized, and the goal of non-trench simultaneous row recovery of bottom pillars was achieved by supplementing short holes. The industrial test results show that after the adoption of the optimized scheme of "pre-controlled roof reinforcement + supplementary short-hole simultaneous row recovery of bottom pillars", the stope roof stability and ore resource recovery rate are significantly improved, the comprehensive production capacity of stopes increases by 21.54% compared with the original scheme, and the loss rate and dilution rate are reduced to 8%, which can be popularized and applied in the underground production area.

A certain iron mine has been using the non-pillar sublevel caving mining method since the start of its operation. Due to severe surface subsidence and high dilution and loss rates of ore, the mine plans to use the filling mining method for the extraction of deep ore bodies. Considering the stability of the ore rock, three filling mining schemes were proposed for areas with poor surrounding rock stability, namely the sublevel filling mining method with pre-controlled roof and rib protection, the upward bench approach filling mining method with pre-controlled roof, as well as the combined mining method of downward approach and upward medium-length hole. After comprehensive comparison of the technical and economic indicators of different schemes and the advantages and disadvantages of each scheme, the combined mining method of downward approach and upward medium-length hole was finally adopted for extracting ore bodies in the unstable deep areas of the mine. Under the condition of fixed mining level height and stope span, numerical simulation was used to optimize the sublevel height. Based on the mine's production capacity requirements, the optimal sublevel height was determined to be 20 meters through optimization analysis. In the mine, the optimized mining method was applied to extract a total of 324 000 tons of hard-to-mine iron ore, generating 69.3 million yuan in revenue and 7.7 million yuan in profit for the mine.

Aiming at the problems of limited mining process and reduced production capacity of deep filling mining method caused by the change of geological conditions in a copper-nickel mine, the process optimization, production capacity check and capacity transition scheme of downward drift filling mining method were studied. Combined with the technical conditions of mining and the current situation of mining methods, in order to realize the continuous and efficient production of downward drift filling method as the optimization research goal, three mining methods were proposed, including downward drift stoping and filling along the strike, downward drift stoping and filling perpendicular to the strike and downward drift stoping and filling obliquely to the strike. Through the comprehensive comparative analysis of the advantages and disadvantages of each scheme and the technical and economic indicators, it is determined that the scheme of downward drift stoping and filling along the strike is the best scheme. The research proposed a capacity calculation method under the condition of continuous mining in the panel. Combined with the occurrence characteristics of the ore body in the middle section of the mine, the panel was divided into three categories, and the production capacity was calculated respectively. On this basis, the calculation of the production capacity of the section was completed, and the capacity transition scheme of the new and old mining processes was formulated. The work deployment of the transition period was clarified. The results show that the optimized filling mining method is technically feasible, safe and efficient, and the capacity transition scheme is operable, which can provide technical support for the mining production and productivity transition of the mine.

Taking the mining area of Tongkeng Mine transition from caving method to filling method as the research object, the thickness of vertical isolation pillar and horizontal isolation pillar calculated by Bieniawski pillar strength formula and K. B. Rupeneyt theory should be less than 9.0 m and 9.36 m, respectively. A three-dimensional fine ore body mining model was established based on FLAC3D, and the influence of the entire mining process on stope stability under different thicknesses of isolation pillar was analyzed. The numerical simulation results show that, when the thickness of vertical isolation pillar is 10 m, the vertical displacement of the stope is less than 0.1 m, the maximum principal stress is 50 MPa, the minimum principal stress is 7.5 MPa, and the safety factor is greater than 8.0.When the thickness of vertical isolation pillar is 8 m, the displacement around the stope increases obviously, the plastic failure zone scope increases obviously, and the safety factor decreases slightly. Therefore, it is recommended that the thickness of the vertical isolated pillar in the mining area of the caving method to the filling method in Tongkeng Mine is 10 m.

Taking the graded tailings backfill of the Shishudi Gold Mine as the research object, the physical and chemical properties of graded tailings and industrial solid waste were analyzed. Using slag powder, steel slag powder and F-gypsum as the main raw materials, and sodium hydroxide, sodium silicate and aluminum sulfate as composite activators, low-carbon solid waste cementitious materials were prepared. Through the mixture design model in response surface methodology, the influence of different mass ratios of components on compressive strength was analyzed, the reliability of the model was assessed, and the optimal proportion of low-carbon solid waste cementitious materials was determined as slag powder∶steel slag∶F-gypsum∶activator=70.69∶10.52∶18.79∶5. Then, XRD, SEM-EDS, and hydration heat analysis were employed to examine the phase composition, microstructure, and hydration kinetics of the low-carbon solid waste cementitious materials. The results indicate that the hydration products of the low-carbon solid waste cementitious materials primarily consist of C-S-H gel, ettringite, and calcite, with the hydration heat release rate and total heat release being reduced by over 30% compared to cement. Pilot-scale tests demonstrate that replacing cement with low-carbon solid waste cementitious materials for gold tailings backfill under the same technical specifications can save more than 50% of cementitious materials, increase tailings utilization by over 10%, reduce backfill costs by over 30%, and cut carbon emissions by 90%, achieving favorable economic and social benefits.

The composite filling structure with strong-weak combination formed by the two-step filling mining bears the roof load jointly, and its overall creep characteristics directly affect the long-term stability of the filling stope. Uniaxial step-loading creep tests were carried out to analyze the influence of different combinations of strong and weak media on the creep characteristics of composite filling specimens. On this basis, considering the time-dependent degradation effect of material mechanical properties and the characteristics of the accelerated creep stage, an improved Nishihara model capable of characterizing the creep characteristics of the composite filling structure was established. The study shows that the strong media has a more significant impact on the overall creep characteristics of the composite specimens. As the strength of the strong media increases from 23.60 MPa to 33.80 MPa, the elastic modulus increases from 1.85 GPa to 2.18 GPa, and the axial creep increments under the first three stress levels decrease by 59.72%, 57.35%, and 55.08%, respectively. The instantaneous creep rates decrease by 31.55%, 21.46%, and 23.14%, respectively. The transverse strain difference between the strong-weak media increases from 260 με, 368 με, and 524 με to 685 με, 895 με, and 1 032 με, respectively. The overall creep failure mode of the specimens transforms from shear failure to compressive splitting failure. The improved Nishihara model achieves a fitting accuracy exceeding 0.93 for the experimental data, effectively simulating the entire creep process of the composite filling structure.