In order to solve the problem of high ore dilution rate and loss rate in the non-pillar sublevel caving method mining of Kizil-Tashtek copper-lead-zinc polymetallic mine, the flow characteristic parameters of ore-rock loose in the target ore section were measured by loose flow parameter test. Based on the ore drawing ellipsoid theory, the drift interval and ore drawing step distance were calculated. Through indoor ore drawing simulation test and on-site industrial test, the control variable method was used to study the drift interval and ore drawing step distance respectively. The stope parameters were optimized with the ore recovery difference as the evaluation index, and the optimal drift interval and ore drawing step distance were determined. The results show that when the drift interval and ore drawing step distance are 18 m and 3 m respectively, the ore drawing caving body and the ore drawing ellipsoid body are highly consistent, and the ore dilution rate and loss rate are reduced to about 12% and 15% respectively, which effectively solves the problem of high ore loss rate and dilution rate.

To solve the mining problem of orebody under the main transport roadway in the middle section of 790 m of a gold mine, an “Arch Bridge Method” mining scheme was put forward. The top pillar and interval pillar of the stope were simplified into a mechanical model, and the safety thickness of the top pillar under two constraints of fixed support and simple support was calculated as 7.09 m using the Reissner thick plate theory. The rationality of the “Arch Bridge Method” of 6 m width isolation interval pillar was verified using the Bieniawski pillar strength calculation formula. The “Arch Bridge Method” mining scheme with the interval pillar width of 6 m and the top pillar thickness of 6 m, 8 m, 10 m and 12 m respectively was designed. The FLAC3D numerical simulation software was used to simulate the influences of the width of the interval pillar and the thickness of the top pillar on the stability of the stope and the main transport roadway. The results show that based on the analysis of the stress field, displacement field, and plastic zone in the stope, the optimal thickness of top pillar for the “Arch Bridge Method” mining scheme is determined to be 10 meters. In the subsequent production practice, the loss rate, dilution rate and ore grade of the “Arch Bridge Method” mining scheme are similar to those of the upward horizontal layered filling mining method in the same stage. The production capacity of the stope is increased by 94.4%, and the transportation capacity of 900 t/d in the main transport roadway of 790 m is maintained, which provides a solution for the same mine problems.

In order to realize the safe and efficient mining of isolated pillars in metal mines transitioning from open-pit to underground mining, Mathews stability diagram method was used to calculate stope parameters. Combined with FLAC3D software, the influence of different mining methods on stope stability was analyzed. Upward drift filling mining method + construction of artificial false roof mining scheme was verified by field test. The results show that the hydraulic radius of the hanging wall of the designed stope is 1.64 m, and the maximum span of the roof without support is 3.5 m, both of which are within the safe range of theoretical calculation. The structural parameters of the stope meet the safety requirements. Under the mining method of skip mining, the maximum compressive stress and maximum tensile stress of the stope are less than the compressive strength and tensile strength of the rock mass, and the formed plastic zone does not penetrate the stope, indicating that the stope is in a stable state. In the field test, the production capacity of a single ore block reaches 100 t/d, the loss rate is 4%, and the dilution rate is 5% after the application of the mining scheme of the upward drift filling mining method + 1.5 m thick reinforced concrete artificial false roof and the mining method of skip mining. The number of ore blocks is stable and the economic benefit is good.

Roadway stability is the foundation of safe production in underground mines, and it is of great significance to study the dynamic damage effects of blasting vibration wave on roadway stability in underground mines. Taking the first subsection of a mine as the research object, aiming at the roof fall accident caused by the blasting vibration at the intersection of the footwall roadway and the approach due to the mining of the ore body during the mining process of the ore body of the non-pillar sublevel caving method, the FLAC3D dynamic analysis module was used to determine the reasonable position of the footwall roadway of the non-pillar sublevel caving method under the blasting load. The results show that the height of the section of the mine is 15 m, considering the vibration velocity, displacement and stress response of the roadway particles, the safe distance between the footwall connection roadway and the withdrawal position is 12 m. The engineering practice shows that the safety distance obtained by the study is obsolute deviation of only 0.7 m (<6%) with the reasonable safety distance of the footwall connection roadway in the mine site, which can provide solutions and technical support for the solution of similar problems in the mines.

Based on the theory of cylindrical charge blasting carter, on-site blasting carter test with variable depth and variable hole spacing were designed and carried out to determine the optimal burial depth and blasting hole spacing. The determined blasting parameters were applied to the coarse sandstone bench of a large open-pit mine in Inner Mongolia. The results indicate that the optimal burial depth range for the cylindrical charge is 1.10 m to 1.16 m, where the energy utilization rate of the charge is high and the volume of the blasting crater is large. The detonation of adjacent cylindrical charges will generate stress wave superposition effect, which gradually weakens and disappears with the increase of hole spacing. The optimal hole spacing is 1.28 m to 1.60 m. The field application results show that the overall shape of the blasting pile is gentle slope, the rock fragmentation is uniform, and the shoveling efficiency is high. Research has confirmed that conducting cylindrical charge blasting crater tests has a guiding significance for optimizing blasting hole network parameters.

In order to reduce the stripping transportation cost of open-pit mines and realize the efficient flow of stripping materials, the optimization design of open-pit mine road was studied. Firstly, the current situation of open-pit mine road optimization design was analyzed, and an open-pit mine road optimization design method based on truck fuel consumption law was proposed. The fuel consumption equivalent coefficient was introduced to reflect the fuel consumption of trucks under various slope conditions, which was convenient for accurate estimation of fuel consumption cost. Secondly, based on the measured fuel consumption data of trucks in an open-pit mine, the fuel consumption characteristics on heavy-haul uphill and no-load downhill for trucks under different slopes were quantitatively analyzed. Finally, according to the fuel consumption law of MT3700 truck, a design method of combined slope was explored by optimizing the slope and slope length of flat road section, and the optimization strategy of open-pit mine road was proposed. The results show that the truck transportation distance of open-pit mine should be controlled within 3.5 km as much as possible, and about 2 km is the best transportation distance. The fuel consumption generated after exceeding 3.5 km generally increases, and the growth rate is faster. The mine road design should reduce the height difference as much as possible and control the height difference within 160 m, among which the fuel consumption efficiency is the highest when the height difference is 80 m. The slope of the mine road is not sensitive to fuel consumption, so the overall slope of the mine transportation road can be appropriately increased to reduce the transportation distance to reduce fuel consumption.

To develop an environmentally friendly and economical coal gangue treatment scheme, and to achieve the goals of efficient resource utilization and environmental sustainability, the environmental problems caused by coal gangue in the Xinjie Taigemiao mining area were targeted. Through comparative analysis of various coal gangue treatment technologies, a reasonable method for gangue treatment was determined. A comprehensive filling technology scheme covering the key links of material preparation, transportation, filling and solidification was designed. The results show that the filling technology is selected as the preferred scheme for gangue treatment because of its environmental friendliness and cost-effectiveness. The high-level grouting technology is used as the preferred scheme for filling mining, and the gangue crushing storage, mixing, pumping system and pipeline system are designed. The technical system includes three processes of high-level grouting, adjacent grouting and low-level grouting, which are suitable for goafs with different conditions. The operation cost analysis shows that the proposed filling scheme is technically and economically feasible. The implementation of this scheme can significantly reduce surface subsidence, reduce environmental damage and improve the comprehensive utilization rate of resources. The scheme not only improves the safety production conditions of the mining area, but also promotes sustainable development and realizes the synergistic improvement between environmental governance and safety production.

Aiming at the problems of large ore depletion rate and serious surface subsidence in Shizhuyuan Polymetallic Mine by caving mining, it is proposed to use filling mining method. Physical and chemical properties test of tailings, static and dynamic flocculation and settlement test were carried out, combined with the actual production capacity of the mine, the optimum thickening parameters of tailings and thickener size were determined. The particle swarm optimization support vector machine (PSO-SVM) was used to establish the sand discharge stability prediction model, and the optimum sand discharge process parameters were obtained. The results show that the optimum type of flocculant is CKYZ-24S, its optimum dosage is 30 g/t, the optimum feed mass concentration of the unclassified tailings is 12.5%, the optimum feeding rate of the tailings is 0.744 t/(m²h), and the diameter of the thickener is determined to be 12 m. The optimum sand discharge process parameters are as follows: the height of the tailings mud layer is 15.2 m, the thickening time is 3.9 h, the flow rate of sand discharge is 96 m³/h, and the average mass concentration of slurry is 70%, with fluctuation of ± 1.5%, which realizes 24 h continuous filling of tailings, and the filling capacity reaches 4 800 m³/d. The research results show that the filling mining method can improve the economic benefits and ensure the green and safe mining of the mine.

In order to study the influences of ultrasonic frequency, power and application time on the underflow mass concentration of unclassified tailings discharge, ultrasonic technology was introduced to explore the effect of ultrasonic coupled with mud layer on the underflow mass concentration and sand discharge of thickener. Firstly, the directivity of ultrasonic in unclassified tailings slurry was analyzed by MATLAB software, and the optimal frequency range of ultrasonic wave was selected. Then, the optimal frequency of ultrasonic was further determined by interpolation fitting method. Finally, the optimal frequency, power and application time of ultrasonic were calculated through the interaction of factors, and verified by support vector regression model. The results show that when the ultrasonic frequency is 28 kHz, the propagation directivity in the thickener is better. Under suitable ultrasonic conditions, ultrasonic has a significant effect on increasing the final mass concentration of unclassified tailings slurry. The optimal operating conditions of the ultrasonic for flocculation settlement of the unclassified tailings are as follows: after the natural settlement of the unclassified tailings for 1 min, the ultrasonic frequency is 28 kHz, and the ultrasonic power is 100 W.

In order to explore methods to accelerate the flocculation settling of fine tailings, ultrasonic technology was introduced during the flocculation settling of tailings. Non-contact sound fields and perturbation actions were applied to the tailings slurry medium to conduct tests on flocculation settling of fine tailings based on ultrasonic guidance. By analyzing the variation of height of solid-liquid of tailings slurry under the action of 28 kHz and 100 W ultrasonic transducers at different settling times, combined with the simulation of the internal flow field of the sand silo, the mechanism of flocculation settling of tailings slurry under ultrasonic guidance was revealed. The results show that compared with natural flocculation settling, ultrasound can significantly increase the settling height of the solid-liquid surface of tailings slurry, and small flocs tend to move upward at the solid-liquid interface and form large flocs in the upper water layer, providing an excessive flocculation environment for flocculation settling of subsequent tailings slurry. Ultrasonic guidance is not only beneficial for the flocculation settling efficiency in current environment, but also has potential advantages for continuous flocculation settling.