The influence of roasting on mineral decomposition under stable magnetic field was investigated. A direct reduction roasting experiment without carbon presence was performed for Bayan Obo lean iron, with roasting temperature of 950 ℃ and magnetic induction density of 1.02 T. Based on the analysis of the loss rate of mineral weight, mineral phase transformation and micro-morphology change by means of TG-DSC, XRD and SEM-EDS, the phase evolution law for rare earth minerals, gangue minerals and iron minerals under magnetic field was revealed. The results show that the decomposition time of bastnaesite is shortened by about 20 min after applying a stable magnetic field, and even the monazite with extremely low decomposition rate is almost completely decomposed after 60 min-roasting process. It is found that magnetic field can promote the decomposition and transformation of gangue minerals that cannot be decomposed without application of magnetism, and also accelerate the migration of alkali metal ions and the replacement of Fe²⁺ with fayalite.

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.

In order to comprehensively recover fluorite resources from the tailings left after hot flotation of scheelite, a beneficiation process consisting of regrinding, water displacement and concentration, and fluorite flotation was proposed. It is shown that with the feed ore with CaF₂ grade of 25.47%, a fluorite concentrate can be obtained with CaF₂ grade and recovery at 92.35% and 60.59% respectively.

A medium-low grade calcium-magnesium phosphate ore was ground to a fineness of 56.74% -0.075 mm and was used to study the liberation characteristics of particle size within varied ranges on its flotation behavior. The particles were classified into coarse ranges (+0.15 mm, -0.15+0.106 mm and -0.106+0.075 mm) and fine ranges (-0.075+0.038 mm and -0.038 mm). The content of different minerals in each size range was estimated by using X-ray fluorescence spectroscopy and X-ray powder diffraction analysis, while the intergrowth and monomer liberation was evaluated with the backscattering images obtained from scanning electron microscopy. It is found that the content of liberated minerals increases as the particle size decreases. Fluorapatite is primarily enriched in the coarser particles within the size range of +0.075 mm, whereas dolomite is concentrated mainly in fine particles of -0.075 mm. By improving the selective aggregation of valuable minerals and gangues in size range of -0.038 mm, the P₂O₅ loss can be reduced. Furthermore, by reducing the content of coarse particles within the size of +0.075 mm and increasing the content of particles within -0.075+0.038 mm range, both P₂O₅ grade and recovery of the concentrates can be effectively improved.

A concept of short delay blasting with blastholes in a combined fan pattern was put forward, in which a row of reinforced holes were added between each row of conventional fan-pattern holes, and detonation was initiated with short delay interval between the conventional row of holes and the added row of holes. The blasting scheme with different delay interval, and blastholes loaded with different confining pressure were numerically simulated with ANSYS/LS-DYNA. It is found that blasting crater cannot be effectively produced by adopting the scheme with conventional holes in fan pattern under high geo-stress environment, while the scheme of short delay blasting with holes in combined fan pattern is more effective in obtaining damaged and ruptured rock, showing better rock breakage effect. In addition, analysis of crack propagation under different confining pressure shows that the blasting crack tends to grow in the direction of the maximum principal stress. The numerical simulation and field engineering practice have proven that when there is an acute angle between the maximum principal stress and that added row of blastholes in fan pattern, that is, higher confining pressure is loaded in the direction of the horizontal row of holes, and lower confining pressure is loaded in the direction of the vertical row of holes, the short-delay blasting with blastholes in such a combined fan pattern can not only improve the rock breakage effect, but also effectively keep rear row of blastholes and the rock mass behind not impacted by the blasting.

Research on redox leaching of intermediate of nickel hydroxide with synergetic effect of nickel sulfide was carried out, and optimum leaching conditions were obtained from tests, including intermediates of nickel sulfide and nickel hydroxide in a mass ratio of 1/10, initial acidity of 4 mol/L, temperature of 90 ℃, liquid and solid in a ratio of 2.0, and a reaction time of 5 h. Under such conditions, the leaching rate of manganese from nickel hydroxide can reach 99.88% and the utilization rate of nickel sulfide is also up to 79.50%. And the leaching residue can be returned as a reducing agent in the reduction and leaching of nickel hydroxide. By using this method, the consumption of both the reducing agent in leaching of nickel hydroxide and the oxidizing agent in leaching of nickel sulfide can be greatly reduced. In addition, the leaching of intermediate of nickel hydroxide can be achieved with synergetic effect of nickel sulfide, which is easy to operate and can be applied into industrial production.

In order to improve the efficiency of lithium extraction by brine adsorption, a process consisting of pre-concentration and adsorption was developed for lithium extraction. Based on the theory of phase diagram of Na⁺, K⁺//Cl^--H₂O ternary system at 50 ℃ and 100 ℃, variation of lithium concentration and lithium loss rate in brine at different temperatures with different evaporation rate was explored in the test, and the adsorption effects of adsorbents on brine before and after pre-concentration were compared. The results show that the concentration and loss rate of lithium in the solution are not affected by evaporation temperature. As the evaporation rate exceeded 40%, the loss rate of lithium in brine increased rapidly. The pre-concentrated brine with concentration of 55 mg/L lithium at an evaporation rate of 40% was adsorbed with manganese absorbent, showing that the lithium adsorption capacity reached 4.25 mg/g after 4 hours, higher than the adsorption capacity of 3.39 mg/g in the original brine without pre-concentration. It is proven that brine pre-concentration can enhance the adsorption effect of lithium brine extraction.

It is difficult to simulate and analyze distribution of seepage field for the slope at the entrance of excavated tunnel during heavy rainfall. Aiming this problem, a slope project at a tunnel entrance was taken for study, and FISH language in the FLAC^3D was redeveloped to determine the permeability coefficient of soil under different saturation state during rainfall infiltration, and the boundary conditions for rainfall infiltration were updated in real time. In addition, the pore water pressure, matrix suction distribution, as well as safety and stability of the slope at the tunnel entrance after different support schemes were all analyzed with different rainfall durations. The results showed that after 24 hours of heavy rainfall, the slope before and after a combined support including anti-slide piles and anchor cables all reached saturation state, that is, the saturation line ran through from the foot to the crest of the slope, while the slope, after benching and being supported with bolt, had its surface soil from the foot to the secondary platform of the slope under a saturated state. As for the slope at tunnel entrance supported by anti-slide pile combined with anchor cable, the variation law of its safety factor during rainfall was consistent with that of the slope without support treatment, showing that the factor of safety tended to be stable after an initial rapid decrease, and gradually reached 1.2. As for the slope after benching and being support with bolt, its factor of safety decreased a little and maintained above 1.8. It is concluded that the factor of safety, excavated earthwork quantity and total investment for the support scheme should be taken into consideration before starting a slope engineering at a tunnel entrance, and a combined support scheme including anti-slide pile and anchor cable is superior to the scheme including benching and support with bolt.

A mineral liberation analysis (MLA) automatic measurement technology was used to not only analyze the composition and dissemination of minerals in a skarn copper ore, but also investigate the characteristics like particle size distribution and mineral liberation degree of raw ore and bulk concentrate samples ground to different fineness. After a preliminarily study on beneficiation technique for such ore based on the obtained results, a processing flowsheet comprised sequentially of grinding, Cu-Pb bulk flotation, regrinding of roughing concentrate and Cu/Pb flotation separation. It is shown that such flowsheet with the primary grinding fineness of -74 μm 70% and the regrinding fineness of -20 μm 75% can produce a copper concentrate grading 20.88% Cu at 70.42% recovery, and 183.9 g/t Ag at 76.78% recovery, as well as a product of sulfur concentrate grading 32.65% S at 91.47% recovery.

The cap specimens of Al_0.4 CoCrFeNi high-entropy alloy were dynamically loaded with a split Hopkinson pressure bar at room temperature, for studying the adiabatic shear sensitivity of Al_0.4CoCrFeNi high-entropy alloy at different strain rates. The results show that the grain size of Al_0.4CoCrFeNi high entropy alloy before and after dynamic loading is about 100 μm and 100 nm, respectively, with about three orders of magnitude difference. The Al_0.4CoCrFeNi high entropy alloy, with a finer grain size after dynamic loading, has lower adiabatic shear sensitivity, which will increase with the increase of strain rate. Within the range in the experiment, the adiabatic shear sensitivity reaches the highest when the strain rate is 3 360 s^-1, forming an adiabatic shear band that is about 2 μm wide and has an angle of 45° with the dynamic loading direction. At this moment, both the critical strain value and the formation energy per unit volume of adiabatic shear are the smallest. The Al_0.4CoCrFeNi high-entropy alloy undergoes significant grain refinement during high strain rate deformation. And the adiabatic shear of Al_0.4CoCrFeNi high-entropy alloy under dynamic loading is attributed to the thermal-viscoplastic constitutive instability of the material.