Noise pollution in mining areas is a prominent problem in the construction of green mines, and achieving precise and continuous monitoring of noise is crucial for environmental protection and occupational health. To address the the problem of insufficient timeliness and continuity in traditional manual noise monitoring applications in mining areas, taking a typical mining area in Hunan Province as the research background, eight functional areas including open-pit mines, beneficiation plants, transportation work areas, and living areas were selected to carry out 24-hour continuous manual and automatic noise monitoring. Linear regression and bias analysis were conducted to verify the reliability of automatic monitoring technology by comparing over 190 sets of equivalent sound level data per hour. The results show that the automatic monitoring and manual monitoring results are highly consistent, with linear regression slopes ranging from 0.983 5 to 1.055 4, correlation coefficients (r) above 0.997, and absolute deviations controlled within ±1 dB. It is fully verified that the automatic noise monitoring system has good applicability and accuracy in complex mining environments. The monitoring data also reveals that the noise level in the production area (70 - 85 dB) is significantly higher than that in the living area(<55 dB), and after conducting prevention and control measures, the sound level has been reduced by about 20−30 dB compared to the source intensity, with significant prevention and control effects. Finally, noise management suggestions are put for forward for the mine.

With the exhaustion of high-grade magnesite resources, it is of great significance to carry out fine purification of low-grade magnesite through beneficiation methods. The most effective beneficiation method for magnesite is flotation, and the key factor determining the flotation effect is flotation collector. The research status of flotation collectors for magnesite at home and abroad was introduced, and the research progress of the interaction mechanism of collectors and magnesite and its gangue minerals were analyzed from two aspects, including macroscopic conventional characterization test technology and microscopic molecular simulation technology. Comprehensive analysis indicates that it is necessary to strengthen the research on new collectors for synergistic impurity removal. The combination of experiments and molecular simulation techniques to verify the flotation performance and mechanism of collectors will be the focus of future research. The new collector should also have the characteristics of green, environmental protection and no pollution while having high selectivity and collecting ability. The research results can provide a reference for the sustainable development of magnesite resources and the development of flotation reagents.

The iron ore resources are abundant in China, but showing poor, fine, miscellaneous characteristics, more than 98% of iron ore resources need to be beneficiation processing to be effectively utilized. Grinding process, as a preparatory process for the processing and utilization of iron ore, plays a crucial role in the subsequent separation indexes. However, it has high energy consumption and low energy utilization rate, especially during fine and ultrafine grinding, which consumes more energy and is not conducive to reducing mineral processing costs. Adding grinding aids in the grinding process is one of the effective measures to improve grinding efficiency and reduce production costs. By reviewing the research and application status of grinding aids in the field of iron ore grinding, the development and application of new grinding aids, the impact of grinding aids on subsequent operations, and the action mechanism of grinding aids, it is pointed out that the selection and application of iron ore grinding aids need to be adapted to the properties of the ore, the grinding environment, and the grinding conditions. It is necessary to strengthen the development of new grinding aids and the research on their impacts on subsequent mineral processing operations, so as to provide guidance for the selection and application of grinding aids in the field of iron ore grinding.

Taking the fine grinding deep separation tailings of micro-fine iron concentrate in a factory in Panxi area as the research object, the TiO₂ grade is 19.51%, and the gangue minerals are mainly pyroxene, chlorite and amphibole. According to the characteristics of the ore, BY series inhibitors were developed and used with MOH collector. The optimal reagent dosage was determined by inhibitor screening test, inhibitor dosage test, collector dosage test and pH condition test, and the flotation closed-circuit test was carried out. The results show that considering the grade and recovery rate of titanium concentrate, it is determined that BY-3 is used as inhibitor, the optimal dosage is 1 500 g/t, the optimal dosage of MOH collector is 2 500 g/t, and the pH is controlled at about 3.5 during roughing. Through the closed-circuit process of "one coarse, one fine and desulfurization, combining one coarse, one sweep and four fine, as well as returning the intermediate ore in sequence for titanium selection", the ilmenite concentrate with a yield of 30.98%, a TiO₂ grade of 46.94% and a TiO₂ recovery of 74.54% and the tailings with a TiO₂ grade of 5.27% can be obtained. The research results can provide a reference for the efficient recovery and utilization of the same type of ore.

An iron tailings in Peru contain valuable metals such as copper, lead and zinc. The copper grade of the tailings is 0.38%, which mainly existing in the form of primary copper sulfide and secondary copper sulfide. The lead grade is 0.79%, mainly occurring in sulfide and carbonate minerals. The zinc grade is 2.68%, mainly occurring in sulfides. The sulfur grade is 8.45%, mainly existing in the form of sulfides. The optimization test of flotation reagent type was carried out by using the process flow of "copper-lead-zinc partially mixed floating, copper and lead-zinc separation, lead-zinc and other floating re-separation". In the mixed flotation roughing operation, lime + CL agent was used as the regulator, butyl xanthate + ester-112 was used as the collecting foaming agent. Sodium sulfide + sodium bisulfite inhibitor system was used in the separation of copper-zinc, and 25^# black powder was used as the collecting foaming agent in the floating and re-separation operation of lead-zinc. A closed-circuit flotation test was designed based on the open-circuit test results of the whole process flotation and the middlings circulation scheme. The results show that the copper grade of the copper concentrate is 22.03%, and the copper recovery rate is 64.93%. The zinc grade of zinc concentrate is 47.12%, and the zinc recovery rate is 72.00%. The lead grade of lead-zinc concentrate is 21.65%, the zinc grade is 25.13%, the lead recovery rate is 58.84%, and the zinc recovery rate is 19.95%.

When oleic acid is used as collector in winter production of a fluorite concentrator in Chengde, due to poor water solubility and dispersion of oleic acid, the collection capacity is insufficient and the low-temperature resistance is poor. It is necessary to heat the slurry to more than 20 ℃, resulting in high production cost and energy consumption. In order to solve these problems, a new type of low-temperature fluorite collector CK-1 was developed using oleic acid with different iodine values to sulfonate and compound-saponification-emulsification. After the application of collector CK-1, the recovery rate of fluorite concentrate increases by 0.77 percentage points compared with the original production index under the condition of normal temperature production in summer. In the case of slurry temperature of 12 ℃ in winter, the beneficiation index is similar to that of the original condition with slurry temperature of 25 ℃ in summer and oleic acid as collector, but the heating cost per ton of ore is reduced by 11.03 yuan, and the flotation without heating in winter is realized, and the economic benefit is remarkable. In the northern region of China, the annual heating cost of fluorite beneficiation in winter reaches tens of millions of yuan, so CK-1 has good application value in the northern region of China.

In order to promote the resource utilization of coal gasification slag (CGS), the effect of composite excitation of four activators on the volcanic ash activity of CGS was studied by response surface method. The compressive strength of the prepared samples at different ages was measured respectively, and then the corresponding activity index was calculated to evaluate the volcanic ash activity. Meanwhile, a quaternary quadratic polynomial regression model for the effects of the dosages of four activators on the activity index was established, and the optimal composite excitation ratio of CGS was obtained through multi-objective optimization. The results show that in the process of composite chemical excitation, water glass has the greatest influence on the 3 d and 7 d activity index of CGS, and calcium carbide slag has the greatest influence on the 28 d activity index of CGS. The multivariate correlation coefficients of the three regression equation models are close to 1, which proves that the model has a good fitting effect. Numerical function of Design-Expert software was used to optimize the multi-objective. The optimal ratio of composite chemical excitation is obtained: the dosage of calcium carbide slag, desulfurization gypsum, sodium sulfate anhydrous and water glass is 0.97%, 1.61%, 2.55% and 10%, respectively. The absolute error between the measured value and the predicted value of the activity index on 3 d, 7 d and 28 d is not more than14%, and the relative error is not more than 7%, indicating that the regression model is reliable.

Research on the exploration and development of hot dry rock is significant for promoting the global energy transition, achieving sustainable utilization of clean energy, and supporting carbon neutrality goals. To comprehensively and macroscopically understand the latest research progress and technological trends in the field of hot dry rock exploration and development, a bibliometric analysis and thematic exploration of relevant papers and patents were conducted. The trend of publication, the trend of patent application, the distribution of major countries and institutions, research topics and research hotspots were analyzed. The results indicate that the global research in the field of hot dry rock is in a period of rapid development, and China has occupied a dominant position in basic research and technology research and development, but there is still room for improvement in research quality and internationalization process. The research hotspots focus on five key areas, including geothermal energy extraction and utilization, genesis and resource exploration of hot dry rock, reservoir mechanical properties and heat storage construction, reservoir monitoring and evaluation, and seismic prediction and control. Among them, the coupling mechanism of high temperature environment and stress, low temperature fracturing technology and the application of nuclear magnetic resonance technology are important research fields in recent years. Although the development and utilization of hot dry rock is gradually entering the engineering demonstration stage, the commercialization still faces challenges such as technical bottlenecks, environmental risks, and insufficient economic viability. Future efforts should focus on advancing geophysical exploration technologies, enhancing heat reservoir modification techniques, optimizing hydraulic fracturing and drilling processes, investigating the dynamic evolution of fracture networks and long-term stability of heat reservoirs, and improving heat extraction and heat exchange efficiency. Additionally, strengthening the integration of fundamental research and applied technologies is critical to overcome technical challenges, reduce development costs, and promote the sustainable utilization of hot dry rock resources.

In order to alleviate the imbalance between supply and demand of some key rare earth metals in the electric vehicle industry, the Gompertz model and the material flow analysis method were used to predict the theoretical demand of electric vehicles in China from 2024 to 2050. The effects of two paths of motor technology innovation and comprehensive utilization of resources on the supply and demand of four key rare earth metals (neodymium, dysprosium, praseodymium and terbium) in the electric vehicle industry were discussed. The results show that under the given scenario of weak motor technology innovation effect, praseodymium and neodymium are in sufficient supply, while dysprosium and terbium are still in short supply by 2050. In the semi-derare earthing scenario and the radical scenario where the effect of motor technology innovation is more significant, dysprosium will achieve supply and demand balance in 2043 and 2039 respectively, and terbium will achieve sufficient supply in 2041 and 2031 respectively. In the path of comprehensive utilization of resources, recycling has a significant effect on alleviating the imbalance between supply and demand of rare earths in the long run, and the overall decline in the output of restricted electric vehicles is 79%. The hybrid vehicle reduces the use of rare earth resources and improves the allocation efficiency. The two paths of motor technology innovation and comprehensive utilization of resources can effectively alleviate the imbalance between supply and demand of key rare earth metals by promoting the development of new quality productive forces.

To address issues such as ventilation difficulties, deterioration of underground working environments, and increased ventilation energy consumption faced by complex high-resistance ventilation systems in ultra-deep mines, a study on quality improvement and consumption reduction of the ventilation system was conducted in Hongtoushan Copper-Zinc Mine. The research and application of complex low-resistance ventilation network construction, main fan setting optimization and remote intelligent frequency conversion control in ultra-deep mines with long strike were carried out by means of field investigation, calculation analysis and practical verification. After the implementation of the technical scheme of quality improvement and consumption reduction of the ventilation system, the ventilation resistance of the whole mine is reduced by 56.39%, the number of main fans is reduced from 4 to 2, and the deep air intake is increased by 36.1 m³/s. The ventilation energy consumption cost can be saved by 3.023 million yuan per year, and remarkable saving-energy and consumption-reducing effect has been achieved. The seven basic indicators of the ventilation system have been greatly improved, with an average increase of 20.43 percentage points, and the underground working environment has been significantly improved. The research results can provide a reference for the study on quality improvement and consumption reduction of ventilation systems in ultra-deep metal mines.