A self-designed multi-functional rod was adopted to provide a real-time monitoring of surrounding rock stability during the excavation of a metal mine, and the variations of vertical stress of rock stratum and surrounding rock vibration occurrence within the monitoring range of the multi-functional rod during stoping were all recorded. It is found that the stress and peak ground velocity of the surrounding rock are all trending up as excavation area increases, which reflects that more fractures occur inside the surrounding rock, leading to lower degree of stability for the surrounding rock, and the excavation damage zone (EDZ) goes deeper. As for mines supported by top threaded anchor bolts, the EDZ evolution process and caving of rock mass can be more effectively controlled when the thread length of rod is greater than the depth of EDZ. After one month's mining of this stope, it is found that the vertical stress of the rock stratum within the monitoring length of the multifunctional rod increases by 3.9 MPa due to the subsidence of the stratum, and the frequency of vibration occurrence meets the blast vibration standard for safety permit in China. It is shown that the surrounding rock has a good stability based on the comprehensive evaluation.

For solving the problems of coarse feed size for grinding and high energy consumption in processing Daye Iron Ore, an experiment was carried out with high pressure roller grinding (HPRG) to mill the fine crushing products. The parameters of pressure between rollers, the water content of feed and the rotational speed at roller surface were optimized correspondingly as 10 MPa, 2% and 0.26 m/s. A closed-circuit test shows that HPRG can obviously reduce grinding energy consumption and improve mineral liberation degree. Jaw crushing and HPRG products were then taken as the feed for grinding-flotation test and it is shown that HPRG can improve flotation recovery, with recoveries of Cu, Fe and S all up by 2.56, 1.93 and 1.44 percentage points, respectively.

By using CFD-DEM coupling approach and Archard wear model, a slurry pump with small flow was numerically simulated under the conditions including different flow rates and particle sizes. Based on the analysis of the movement law of particles in the pump, the distribution of particles in different regions of pump and the collision between particles and wetted parts of the pump, the wear characteristics of wetted parts in the slurry pump, especially the volute were studied. The results show that there is some blockage in the volute approaching the tongue region due to a slow flow rate of particles. It is found that wear of the volute is mainly concentrated on the upper part and near the tongue region. With the increase in the flow rate and velocity of particles, the kinetic energy of the particles collide with the pump wall increases, resulting in serious wear on the body of slurry pump. And the wear will become more serious by the particles with small grain size.

Aiming at complicated flow field of Y-shaped pipe in pump piping system and risk of ore leakage in conveying test for deep sea mining, numerical simulation was performed by using CFD-DEM method for ore particles with different velocities, different volume concentration and different particle sizes. Based on that, the movement features of particle groups and flow field distribution pattern in Y-shaped pipe were all analyzed. It is found that the flow field distribution in Y-shaped pipe is influenced by the curvature of pipe elbow and the flow distribution in the inlet of Y-shaped pipe. The particle groups flow against the inner wall of elbow, and deflect upward under the influence of upward flow. If upward flow with lower velocity, particles with large grain size and high volume concentration will hit the bottom of pipe, leading to some losses. As the upward velocity decreases and both particle volume concentration and grain size increase, more and more particles will be continuously lost on the bottom of pipe. Due to the existence of particle flow, both intensity and scale of the low-pressure vortex region in Y-shaped pipe become weaken.

A technique combining mechanical force and heating effect was adopted to selectively disassociate cathode material from spent lithium-ion batteries and roll the aluminum foil by adjusting processing parameters. The results show that a better disassociation effect can be obtained with the frequency of electric motor, air circulation fan and dissociation device at 40 Hz, 40 Hz and 50 Hz, respectively. The aluminum foil with particle size of -1.7+0.075 mm is rolled to be spherical, and the cathode materials with particle size of -0.075+0.048 mm and -0.048 mm are rough on the surface and wrapped by organic binder. The final dissociation rate of cathode sheet can be up to 96.35%, and the cathode material can be recovered at a rate of 94.95% by single operation, with the content of Al impurity less than 0.15%. It is shown that this selective dissociation technique based on a combination of mechanic force and heating effect can actualize an efficient separation and sorting of cathode sheet, not only shortening the battery disposal process flow but also achieving efficient metal enrichment.

A Fe-based cladding layer was prepared on the surface of 27SiMn steel by using laser cladding technique, and effect of preheating on the microstructure and mechanical properties of the heat affected zone (HAZ) of 27SiMn steel was investigated. The results show that a large amount of martensite appears in the HAZ of 27SiMn steel after laser cladding process. The tensile fracture is composed of river-pattern cleavage plane, tear edge and dimple, representing a quasi-cleavage fracture; preheating treatment effectively reduces the amount of martensite and brings pearlite structure. When the preheating temperature is 100 ℃, the quenched layer has its hardness decreased by 25.4%, elongation increased by 11.5%, and tensile strength decreased by 14.3%. When the preheating temperature rises to 300 ℃, ductile fracture occurs in the material under tensile force. Appropriate preheating can effectively reduce the martensite in the HAZ of 27SiMn steel and alleviate the decline in the toughness of 27SiMn steel caused by quenching, thus improving the safety during the service of hydraulic cylinder made of laser cladded 27SiMn steel.

In processing a mud-bearing high-silver lead-zinc sulfide ore, collectors of dimethylphenyl dithiophosphate and aniline aerofloat were used in combination to collect lead minerals in a low alkali environment, while the noble metal of silver was comprehensively recovered. Furthermore, lime combined with 8372CN were used to depress pyrite in zinc flotation process, thus alleviating the influence of sludge on the quality of zinc concentrate. The closed-circuit flotation test yielded a lead concentrate grading 67.18% Pb at 94.57% recovery, 2 560.37 g/t Ag at 80.54% recovery and 3.60% Zn, and a zinc concentrate grading 51.63% Zn at 93.27% recovery. With this flowsheet, an efficient comprehensive utilization of a mud-bearing high-silver lead-zinc sulfide ore can be actualized.

An experiment on flotation of calcite in pulp with pH of 8.0 and the dosages for sodium silicate and sodium oleate respectively at 300 mg/L and 1.5 × 10^-4 mol/L was performed by using ultrasonic wave with the frequency at 40 kHz, for investigating the influence of ultrasonic power and sonication duration on the flotation behavior. The variation of sodium oleate content on the surface of calcite was analyzed by adsorption measurement, the chemical status of elements on the calcite surface was analyzed by XPS, and the variation of adsorbed reagents was also analyzed by zeta potential measurement. After 15 min-ultrasonication (40 kHz, 150 W), the flotation recovery of calcite can be increased from 8.5% to 82.7%. It is found that ultrasonication can bring in an increase in the adsorbed amount of sodium oleate on calcite, a decrease in the intensity of Si2p on calcite, and also an increase in the content of C1s. Meanwhile, the deconvolution of O1s spectrum shows reduction in the peak area of sodium silicate, but an increase in that of sodium oleate, and the surface zeta potential of calcite almost unchanged. The results indicate that the ultrasonication can induce a desorption of sodium silicate from the depressed calcite in the pulp containing both sodium silicate and sodium oleate, thus the freshly vacancy can be adsorbed by sodium oleate, leading to the significant improvement in floatability of calcite.

In order to protect ecological environment during exploitation of coal resources in lake, a mining mode with distributed ecosystem was developed for lake mining area, and the function mechanism of such system was explored. In such mode of lake mining, an ecosystem is composed of six subsystems, including biological function system, ecological water treatment and utilization system, ecosystem development and utilization system for land resources, organic fertilizer processing system, integrated energy utilization system, and ecosystem utilization system for solid waste resources. These subsystems can not only function alone but also interact with each other, thus forming mechanisms for life cycle, metabolism, balance, combination, sharing and cooperation. With these mechanisms as the theoretical basis for the distributed ecosystems in lake mining area, effective exploitation of lake resources, sustainable development of ecological environment, as well as promotion of economic benefit from lake resources mining can be actualized by recycling the resources among those six distributed subsystems. This study can provide reference for underwater coal resources mining while ensuring ecological conservation.

Qingdao Metro Line 8 was taken as an example for studying the surrounding rock stability of underground tunnel in mud-containing sandstone stratum with pore water. Based on the analysis of deformation and stress evolution law of surrounding rock by simulating three different pore water conditions, the maximum values of vertical displacement (roof subsidence), horizontal displacement (side walls moving closer), vertical stress, horizontal stress and shear stress of the tunnel were finally obtained. The numerical simulation results of tunnel with three kinds of pore water content were applied to the tunnel construction for Qingdao Metro Line 8, and the on-site monitoring results show the deformation of surrounding rock of tunnel roof and side wall is all controlled within the safety range. It is shown that such numerical simulation results provide good reference for the construction of Qingdao Metro Line 8.