ZnO narowires were synthesized by adopting hydrothermal synthesis, and ZnO/activated carbon composite material was then prepared by compounding activated carbon powder and nano-ZnO. The research on the sensing performance of such composite to ethanol gas shows that the sensor with ZnO/activated carbon composite presents good response and recovery characteristics to ethanol gas at 150 ℃. Its sensitivity to the ethanol with concentration of 5 × 10^-6 can be up to 4.75, and will increase positively with the increase of ethanol concentration, which presents a reproducibility and stability.

In consideration of safety problem of landfilling into a dump with inclined foundation in an open-pit mine, an inclined foundation model and an anti-slide coal pillar model were established based on the analysis of landfilling methods in such inclined dump, deformation characteristics and sliding mode of inclined foundation, and then the method for evaluating stability of anti-slide coal pillar and influencing factors of the stability coefficient of dump slope were all discussed. The research results show that the stability of anti-slide coal pillar mainly depends on the relationship between the internal friction angle of coal pillar and the rest angle of waste material. When the internal friction angle is greater than or equal to the rest angle, the stability coefficient of dump slope increases with an increase in the length of anti-slide coal pillar; while when the internal friction angle is less than the rest angle, the stability coefficient of dump slope increases first, then falls down and finally increases again as anti-slide coal pillar becomes longer.

A 5 mm thick DL510 ultra-high strength steel (1 500 MPa) was welded by using metal active gas (MAG) arc welding. The influence of heat input on the microstructure and mechanical properties of weld joint was investigated, and the residual weld stress of the joint was eliminated by hammering while welding. The results show that with heat input within the range of 43-70 kJ/cm, the obtained weld joints can have a good shape. If hammering time is less than 20 min, the tensile strength of weld joint increases as hammering time prolongs; however, after hammering time exceeds 20 min, there is little variation in the tensile strength. With the increasing of heat input, the grain size of weld joints grows obviously, and a small amount of fine granular bainite structure appears in the coarse-grained area with the heat input of 70 kJ/cm, leading to improvement in the toughness of weld joints.

A technique featuring separated treatment and recycling was introduced to process a mineral processing wastewater from a tungsten-copper ore concentrator. The wastewater from copper tailings precipitation and copper concentrate filtration is recycled for copper flotation, while the water from tungsten concentrate filtration is returned to the cleaning stage in tungsten flotation. They all can meet the water quality requirement in beneficiation. Tungsten tailings water can be reused in grinding and tungsten flotation after intensified treatment by lime flocculation and Fenton oxidation processes. In a close-circuit test, each type of wastewater from different beneficiation processes was separately returned to the corresponding stages based on its quality, and the obtained technical indicators were equivalent to those from the tests with fresh water.

In an experiment, with hydrochloric acid as leaching agent and NaClO₃ as oxidizing agent, lithium was selectively leached from cathode material of spent lithium iron phosphate battery, and the effects of factors, including dosage of hydrochloric acid, solid-liquid ratio and reaction time, on the lithium leaching rate were investigated. It is shown that with an addition of hydrochloric acid at an amount of 1.0 time theoretical value, solid-liquid ratio of 1∶3 and reaction time of 3 h, the average lithium leaching rate can reach 99.33% by using this process. After that, magnesium hydroxide and sodium hydroxide were added into the raffinate in turn to remove impurities of P, Al and Fe. And then, the obtained solution was used to prepare Li₂CO₃ at 95 ℃ by adding anhydrous sodium carbonate. After water washing to remove NaCl, a high purity Li₂CO₃ (99.62%) can be obtained, which meets the industrial standard for industrial-grade lithium carbonate.

Based on the study of process mineralogical properties and grindability of an iron ore from Australia, experiments were carried out to explore its beneficiability. The results show that this kind of ore has a TFe grade of 34.90%, with magnetite and hematite as the dominant Fe-containing minerals, and quartz as its dominant gangue mineral. The ore is medium hard, with a protodyakonov coefficient of 3.13, and also comparatively hard to mill, with a Bond ball milling work index of 13.27 kW·h/t. On this basis, a flowsheet consisting of sequentially primary grinding, a roughing process of low-intensity magnetic separation (LIMS), secondary grinding and a cleaning process of LIMS was adopted in an experiment, producing an iron concentrate grading 65.45% TFe at 65.98% recovery, with mFe recovery of 95.69%. After intensified grinding, the iron concentrate was subjected to further magnetic separation, resulting in ultrapure iron concentrate grading 71.90% TFe at 60.20% recovery. Meanwhile, the middlings was subjected to a scavenging, and a super-high grade iron concentrate with TFe grade of 69.87% was obtained with recovery of 35.21%, indicating that this ore has a good beneficiability.

A hydrochloric acid leaching process was adopted to recover rare earth from rare earth polishing powder waste. The effects of hydrochloric acid concentration, leaching temperature, leaching time and liquid-solid ratio on the leaching rates of rare earth and main impurity Al₂O₃ were investigated, and the leaching mechanism was also discussed. It is found that the optimal conditions for single-stage leaching with HCl system are as follows: HCl concentration of 8 mol/L, leaching temperature of 80 ℃, leaching time of 3 h, and liquid-solid ratio of 4∶1. Under such conditions, the leaching rates of rare earth and Al₂O₃ are 90.81% and 43.68%, respectively．Based on the comparison of results from single-stage leaching, two-stage leaching and three-stage countercurrent leaching, it is shown that the leaching rate of rare earth by three-stage countercurrent leaching can be up to 98.38%. An increased amount of rare earth in the leaching solution is beneficial to the extraction and recovery of rare earth elements in the next step, thus greatly cutting recovery cost.

In order to investigate the influence of additive on iron recovery from red mud by using a process consisting of magnetizing roasting and low intensity magnetic separation, a kind of red mud containing high content of iron and aluminum was taken for experiments. It is found that addition of dolomite and phosphogypsum won't bring any effect to iron recovery, but sodium sulfate can bring an obvious activation effect. In the experiment, the roasting process ran at 650 ℃ for 90 min, with the addition of sodium sulfate at an amount of 10%, with total gas flow at a rate of 500 mL/min and CO at a volume fraction of 30%. And then, the obtained calcine, after being ground to a fineness of -0.045 mm 65%, was subjected to a magnetic separation with magnetic intensity of 68.8 kA/m, yielding an iron concentrate with 60.65% TFe grade at 94.01% recovery. The subsequent thermodynamic analysis showed that at the temperature within the tested range, both dolomite and phosphogypsum were conducive to the decomposition of iron olivine rather than iron spinel, while sodium sulfate could work for both.

Three kinds of solid wastes including fly ash, carbide slag and refining slag were taken as raw materials for preparing a kind of absorbent by adopting microwave modification method and adjusting the proportions of three wastes. Fly ash was mixed with carbide slag in a mass ratio of 1∶1, and refining slag was modified by microwave (with microwave power of 200 W, time of 30 min), which was then added in quantities of 50% by total weight of fly ash and carbide slag. All mixed materials were then pressed under the pressure of 10 MPa, and the prepared adsorbent showed to have a good adsorption performance, with which the desulfurization rate and denitration rate for the sintering flue gas can reach 97.9% and 93.0%, respectively.

With a transport roadway at+392 m section of №92 ore body in Tongkeng Mine as an example, the testing area was firstly divided for investigating the required on-site data. Then, the roadway roof rock was scored by using mining rock mass rating (MRMR) system for rock quality classification and rating. Finally, an appropriate support measure was proposed for the roadway roof based on the grading result. It is shown that the roof rock mass has its score of 50 by RMR system and is rated to be Grade Ⅲ. However, with the modified MRMR system, the rock mass has its score of 29 and is rated to be Grade IV. Compared with the on-site actual investigation of structural plane, the rating result by using MRMR system is much more consistent with actual situation.