Aiming at the problems of spatial information loss in traditional 2D images and the one-sidedness of single-cell data during the identification of coal slime flotation froth, a multi-cell feature fusion method based on 3D point cloud data was proposed. The Percipio Infrared Binocular FM855-E1 industrial camera was used to collect the 3D point cloud data of the froth surfaces from each flotation cell. Preprocessing and data augmentation techniques were adopted to optimize the dataset. A PointNet network with non-shared weights was utilized to extract the high-dimensional features of each cell. After dimensionality reduction by a multi-layer perceptron, these features were fused into multi-cell forth features through a concatenation function. Finally, the working condition categories were determined by a combination of a multi-layer perceptron and the Softmax function. The experimental results show that the classification accuracy of the multi-cell network reaches 94.89%, which is higher than other networks, the loss value is reduced to 0.216 9, with excellent robustness and generalization ability. It is proved that the multi-cell forth feature fusion method can significantly improve the recognition accuracy of flotation conditions, and provide a high-reliability three-dimensional visual solution for the intelligent flotation of coal slime.

In order to meet the requirements of lightweight and explosion-proof safety of coal mine equipment, a type Ⅰ non-metallic lightweight explosion-proof enclosure with a volume of 19.5 L was prepared by glass fiber/epoxy resin composite (GF/ER). The comprehensive performance of GF/ER explosion-proof enclosure was analyzed by material performance tests, finite element simulation and multiple explosion-proof safety tests. The results show that the GF/ER explosion-proof enclosure meets the requirements of high mechanical strength, high flame retardancy (V-0 grade) and antistatic property of underground coal mine equipment. The change rates of tensile properties, bending properties and impact strength of GF/ER explosion-proof enclosure are less than 10%, indicating that it has excellent durability and environmental adaptability. In the reference pressure test, the maximum explosion pressure of the GF/ER explosion-proof enclosure is 0.496 MPa, the ultimate bearing capacity is 3.1 MPa, far exceeding the standard requirement of 1.5 MPa. Under the working load, the gap deformation of the GF/ER explosion-proof enclosure is less than 0.15 mm, and the structure is stable and reliable. Compared with the same size metal explosion-proof box, the GF/ER explosion-proof enclosure achieves more than 50% weight reduction effect, significantly reduces the burden of downhole operation, and improves the endurance of mobile equipment. The research results can provide a feasible technical path and theoretical basis for the lightweight of mining equipment.

Anshan-type hematite accounts for about 55.20% of the total identified iron ore resources in China, and its flotation generally requires high temperature (about 35 ℃ or more) conditions, which increases the production cost. Therefore, the flotation behavior of hematite and quartz was studied with a self-developed MY-type collector and compared with the sodium oleate flotation system. Utilizing detection and analysis techniques such as contact angle, Zeta potential and infrared spectroscopy analysis, the action mechanism of MY on mineral surface was discussed. The results of single-mineral flotation experiments show that under the temperature range of 15-35 ℃, the pH of 11.5, and the dosage of 200 mg/L, the MY-type collector can achieve recovery rate of quartz and hematite exceeding 87.25% and 92.50% respectively. At 25 ℃, under the interaction of the three agents of starch, CaO, and collector, the maximun difference in single mineral recovery rate of quartz and hematite is 89.25 percentage points under the MY flotation system, which significantly improves the difference in the flotation of quartz and hematite compared to the sodium oleate flotation system (the maximun difference in recovery rate is 56.25 percentage points). The mechanism analysis results indicate that MY collector exhibits multifaceted synergistic adsorption effects on quartz mineral surfaces, including electrostatic adsorption, hydrogen bonding, and chemical bonding, while on hematite surfaces, it primarily involves molecular adsorption and electrostatic adsorption. Due to the presence of multiple active groups such as S＝O, —NH₂ and C＝O in its structure, MY forms coupled synergistic interactions across multiple active sites, enhancing its quartz recovery capability. This also amplifies the floatability difference between quartz and hematite, effectively promoting the separation of hematite and quartz in the room-temperature reverse flotation system.

Taking a graphite ore in Luobei, Heilongjiang Province as the research object, in order to improve the fixed carbon content of graphite flotation concentrate, through pure mineral flotation test, the mechanism of typical gangue quartz entering graphite concentrate was analyzed, and the effects of ultrasonic time and ultrasonic power on the flotation of graphite and quartz artificial mixed ore were explored. The actual ore flotation test was carried out by ultrasonic assisted process to evaluate the effect of ultrasonic pretreatment on the fixed carbon content of graphite concentrate. The results of pure mineral flotation tests show that graphite forms flocs under hydrophobic interaction, causing fine-grained quartz to enter the concentrate through entrainment and inclusion. Ultrasonic pretreatment can strengthen particle dispersion, reduce water recovery and reduce quartz floating. The actual ore flotation test show that the graphite concentrate with fixed carbon content of 94.61% and recovery rate of 81.66% is obtained by using the open-circuit flotation process of "five grindings and six flotations" and ultrasonic pretreatment for 3 min before the third re-election to the sixth re-election flotations. The fixed carbon content of the concentrate is 3.10 percentage points higher than that without ultrasonic treatment. The research results provide a reference for improving the fixed carbon content of graphite concentrate in the re-grinding and re-flotation stage by ultrasonic assisted process.

To improve the inhibition performance of causticized starch and the recovery rate of iron concentrate in the process of reverse flotation desilication of iron ore, the Box-Behnken design of response surface methodology was adopted to systematically investigate the effects of three factors of causticizing time, causticizing temperature and causticizing ratio, as well as their interaction on the recovery rate of iron concentrate. The results show that causticizing temperature exerts the most significant impact on the recovery rate, with the order of significance of influence being: causticizing temperature >causticizing time >causticizing ratio. Among them, the interaction between causticizing temperature and causticizing ratio also has a significant effect. The optimal preparation conditions obtained through optimization are as follows: causticizing temperature of 95 ℃, causticizing time of 80 min, and causticizing ratio of 0.07. Under these conditions, the recovery rate of iron concentrate reaches 63.65%, which is 1.3% higher than that under the initial conditions. Infrared spectroscopy analysis results show that after optimization of preparation conditions, the intensity of O—H, C＝O, C—OH and C—O—C characteristic peaks of causticized starch is significantly enhanced, indicating that the intramolecular hydrogen bond network is more stable, the structure is more orderly, and the inhibition performance is significantly improved. The research results verify the effectiveness and reliability of the response surface methodology in the optimization of flotation reagents, and provide a theoretical basis and technical support for the industrial application of causticized starch.

To provide a basis for the feasibility evaluation of comprehensive utilization of a certain tungsten polymetallic mineral resource, detailed process mineralogy studies and preliminary beneficiability evaluations were carried out. Firstly, the mineral liberation analyzer (MLA), combined with various analytical methods such as microscopic identification, chemical analysis, X-ray diffraction analysis, was employed to investigate the chemical composition, material composition of the ore, as well as the key process mineralogy characteristics such as the output form, dissemination particle size and dissociation degree of the main target minerals. Then, according to the characteristics of the ore, the main mineralogy factors affecting the beneficiation effect were discussed and analyzed. It was recommended to adopt the beneficiation process flow of "pre-concentration and discarding waste-gravity separation and enrichment-selection and quality enhancement-fine mud returning to the circuit-comprehensive recovery of sulphide ores". The process of "flotation-shaking table gravity separation-centrifugal gravity separation" was simplified, and ore beneficiability tests were conducted. The results show that the original ore belongs to granite-type disseminated tungsten ore containing molybdenum and bismuth. The main valuable component is WO₃, with a content of 0.31%. The main associated components are Mo and Bi, with contents of 0.043% and 0.024%, respectively. Sulfide ores with Mo grade of 1.40% and Bi grade of 0.79%, and recovery of 97.51% and 84.67%, respectively, and tungsten concentrate with WO₃ grade of 69.00% and recovery of 76.58% are obtained by beneficiability tests. The total recovery rate of WO₃ is 87.04% if the WO₃ in fine mud rough concentrate and tungsten intermediate ore is included in the calculation. The test verifies that the ore has good beneficiability and recovery value.

The comprehensive utilization of tailings is one of the key aspects of green development in the mining industry, and the preparation of geopolymers by tailings holds significant promise. Due to the low reactivity of tailings, thermal-alkali activation can effectively enhance their reactivity, thereby optimizing the performance of geopolymers. To characterize the changes in phase composition and chemical bonds during the activation process, exploring the activation mechanism, X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) were employed. The results indicate that the 7-day compressive strength of thermally-alkali-activated tailings geopolymers can reach up to 15.58 MPa, representing a more than tenfold increase compared to non-activated samples. The compressive strength of the geopolymers improves with the rise of alkali content, calcination temperature and calcination duration. During the thermal-alkali activation process, muscovite in the tailings undergoes structural distortion through group substitution and is converted into an amorphous phase. The alkali content and calcination temperature has a notable impact on the activation effect. The research findings can provide a theoretical foundation for the selection and activation of tailings in geopolymer preparation.

Based on the continuous mining project of the deep double middle sections in the second mining area of Jinchuan Nickel Mine, numerical analysis of ground pressure control in the panel of deep double middle sections was carried out. By comparing the distribution of maximum unbalanced force, stress, and displacement field in the lower panel under five different schemes of ground pressure control technology, it was found that Scheme Ⅴ (advanced unloading through the upper and lower panels and trapezoidal approach with two mining intervals) had the best ground pressure control effect, with the lowest extreme value of maximum unbalanced force (1.20×10⁸ N). The maximum principal stress of the backfill at the top of the panel was negative and no tensile stress was observed. Compared with Scheme I (advance unloading through the vein in panel and rectangular approach with one mining interval), Scheme V has an average minimum principal stress increase of 0.11％ and a maximum compressive stress increase of 1.56％. During the mining process, the tilting deformation of the backfill on the roof of the panel is minimized. The optimization of the ground pressure control technology scheme for the deep double middle sections shows that the “positive trapezium + concave” technology scheme has smaller stress fluctuations and displacement deformations, and the ground pressure control effect is better. The application and stability analysis results of deep mining engineering show that after adopting the optimized scheme of ground pressure control technology, the ore output of the mining area can meet the production capacity requirement of 4 million tons per year. The increase in frequency of microseismic events is relatively slow, and microseismic events occur uniformly without sudden clustering. The overall frequency coefficient of roadway damage in the 1 000 m middle section shows a decreasing trend year by year, which verifies the rationality of the ground pressure control technology scheme for the panel in deep double middle sections.

The Xitieshan lead-zinc mine has left a large amount of high-grade ore pillar resources after years of mining, and there is an urgent need to recover the top and bottom pillars in a safe and efficient manner. It is found that the strength of underground filling body can't meet the conditions for large-scale exposure in the bottom pillar mining area through on-site sampling and strength testing of the filling body above the bottom pillar, and it is necessary to leave roof protection pillars. Based on the test results, three technically feasible mining schemes were proposed, including the joint mining method of sublevel open stoping with subsequent filling and upward access empty field, mining method of false roof and segment subsequent filling, as well as mining method of pre-controlled roof and downward medium and deep hole segment subsequent filling. A comparative analysis was conducted on the advantages, disadvantages, and technical and economic indicators of the three mining methods. Finally, the the joint mining method of the segmented subsequent filling and upward access was selected. Numerical simulation was used to determine that the medium deep hole mining area adopts the mode of mining one with two intervals, and in a sequence from both sides to the middle, and a backward extraction method was used to extract partially pillars during the mining process of the access. The on-site application results show that this scheme has good safety and adaptability in the mining of top and bottom pillar resources, with a comprehensive recovery rate of 70％, achieving efficient recovery and utilization of top and bottom pillar resources.

The ore body above 180 m level in the west section of Dahongshan Copper Mine belongs to the gently inclined medium-thick ore body, which was originally mined by the point-column upward horizontal slicing-and-filling method. However, with the continuous expansion of the mining scope and level, the stress concentration around the mining zone became increasingly evident, the unmined areas and the stope were located within the stress concentration zone and the plastic zone, leading to a growing safety risk for the roof. According to the characteristics of ore body and the actual situation of the site, the optimization study of mining in transition area between two minging schemes was carried out. After optimization, the transition area was mined using the sublevel open stoping with subsequent filling method, and cemented backfilling was employed to construct cemented ore pillars in the transition area. Analysis and study on the layout of mining preparation projects in the transition area under two mining schemes were carried out. The results show that the transition area is mined by sublevel open stoping with subsequent filling method, and the cemented pillar formed by cemented filling has a good supporting effect. The maximum plastic zone height of stope roof is 7-8 meters, and the layout of the filled return airway is not affected. The application effect shows that the stope in the transition area remains stable overall, achieving safe and efficient resource recovery in the area.