To address the problem in the existing grinding and classification system in Luzhong concentrator, the 5^# grinding and classification system in the concentrator was optimized and upgraded by the following measures, including optimizing the working conditions of the autogenous mill, adding pre-concentration process with magnetic pulley for the oversized material of the drum screen and wet pre-concentration process before the ball mill, replacing the spiral classifier with a hydrocyclone group. Those measures can not only increase the actual processing capacity of 5^# system to 232 t/h from 186 t/h, but also discard waste ore grading 7.05% TFe with a yield of 5.40%, presenting an iron loss rate of 1.25%. Meanwhile, +0.5 mm coarse sand can be produced with a yield of 12.63% and an iron loss rate of 3.86%. It is shown that in the first-stage overflow of the hydrocyclone, 44.09% product grading 53.00% TFe is yielded, indicating a good effect by optimization and upgrading measures.

The parameters of the Fuzzy Measure Method (FMM) in slope stability analysis are difficult to determine, thus a support vector regression (SVR) model was established and used to accurately predict parameters of the FMM, and a slope stability prediction model, FMM-SVR, was established, which was then used to predict the instability probability of the slope during the second-phase open-pit mining in Gaocun Iron Mine of Masteel Mining Resources Corporation. The results show that the maximum slope instability probability is 0.120 8 as mining operation approaches the toe of slope in an open pit, indicating that the slope remains overall stable with a risk of partially instability. This conclusion is also consistent with the on-site measured results. The location of the most critical sliding surface of the slope was determined by the finite element strength reduction method, and the factor of safety is calculated to be 1.5, which further verifies the effectiveness of the FMM-SVR model.

The additive manufacturing of SiC_p/Al606 by photocuring process was studied, and the effects of resin monomer and solid volume fraction on the stability, rheological properties and photocuring performance of SiC_p/Al6061 slurry, as well as the compactness and microstructure of sintered product were explored. The results show that as photosensitive resins of PEG200DA and PEG400DA mixed at an appropriate ratio of 1∶1, the prepared slurry with content of 52.5%, viscosity of 5.05 Pa·s (shear rate of 10 s^－1) and single-layer curing thickness of 100.3 μm can meet the requirements for photocuring in additive manufacturing. The SiC_p/Al component manufactured by photocuring process can have a complete structure and good interlayer bonding, and the sintered product with no cracks and obvious necking presents relatively high compactness (94.07%).

The mechanical properties and energy evolution law of dolomite under a combined action of dry-wet cycle and cyclic loading and unloading were explored. The results show that the structural damage caused by dry-wet cycles leads to the transformation of dolomite from brittle fracture to ductile fracture, which is manifested by an increase in the area of hysteresis loops and a decrease in peak strength. At the early stage of cyclic loading and unloading, a strengthening effect is observed, and then the dolomite develops into the strain-softening and damage stages. An energy analysis indicates that the total input energy is mainly stored in the form of elastic strain energy, and the proportion of dissipated energy increases slowly with the accumulation of damage. Additionally, based on the variation of the damage variable defined by dissipated energy, the damage evolution tends to be stable after a progressive and accelerated process.

To explore the removal mechanism of silicon and calcium and optimize the process, simulated chlorinated slag composed of silicon dioxide, calcium chloride and sodium chloride, was used as raw material in an experiment, with sodium hydroxide as an additive. The calcium and silicon ions were converted into high-melting-point solid phases, which were separated from the sodium chloride salt solution by filtration, thereby realizing regeneration and comprehensive utilization of the sodium chloride salt solution. Based on thermodynamic analysis, kinetic analysis, TG-DSC, XRD, ICP, SEM-EDS among other analysis measures, the conversion at high temperatures and removal mechanisms for calcium and silicon impurities, as well as the separation process of NaCl were all systematically explored. Thermodynamic analysis shows that a conversion can proceed spontaneously at temperatures ranging from 973 K to 1473 K. Fitting with the Kissinger method shows that the activation energy of the conversion at high temperatures is 296.21 kJ/mol, and the pre-exponential factor is 8.46×10¹⁰ s^－1. The experimental results indicate that with calcium-silicon impurities and sodium hydroxide in a mass ratio of 1∶0.6, separation by filtration at 1 123 K can lead to the removal rates of calcium and silicon up to 86.66% and 99.60%, respectively.

A beneficiation test was performed with a kind of fine-grained refractory fluorite ore in Hunan Province for rational development and utilization. In the test, a process consisting of coarse grinding, pre-concentration, regrinding and re-concentration of rough concentrate was adopted, with CYP-01 as a collector, sodium carbonate as a modifier, and water glass as a depressant. Depression in steps was performed in the cleaning stage. With the coarse grinding fineness of －0.045 mm 50%, regrinding fineness of－0.045 mm 85%, a kind of chemical-grade fluorite product with CaF₂ grade of 93.04% was obtained at 64.24% recovery after one stage of roughing and eight stages of cleaning. It is shown that such kind of fine-grained refractory fluorite ore can be effectively recovered and utilized.

A 3D heterogeneous numerical model was established based on the C6^# mining area of the Bayan-Uul uranium deposit to analyze the effects of different horizontal permeability in the filter section on solute transport, pH value and uranium mineral leaching performance. The simulation results show that after 450 days, the uranium leaching rate is 13.56% at the vertical depth of 30 m in the filter section, presenting 22.71% higher compared to the leaching rate of 11.05% at the depth of 35 m. According to the sandstone permeability, grade of uranium in the stratum and heterogeneity, the vertical arrangement position and length of filter section can be optimized, so as to effectively improve the economically recoverable metal quantity.

Martensitic steel with different ferrite content and distribution was firstly fabricated by heat treatment. Then, the effects of ferrite content and distribution on the microstructure and properties of such ultra-high strength martensitic steel with yield strength more than 1 100 MPa was explored based on microstructure characterization and mechanical property tests. The microstructure evolution and strengthening and toughening mechanism were also analyzed. The results show that with a small amount of ferrite uniformly distributed in the martensite matrix, the steel sample in the experiment can exhibit not only ultra-high yield strength (1 245.44 MPa) and tensile strength (1 411.96 MPa), but also higher impact energy (80 J) at low temperature, presenting the optimal comprehensive mechanical properties. A small amount of ferrite in the local area continuously distributed along the rolling direction can slightly improve the tensile strength, but the unevenly distributed ferrite can improve the stress concentration and reduce the toughness. An increase in the content of continuously distributed ferrite can improve the tensile strength, but the formation of banded martensite and improved stress concentration make the toughness of the steel sample in the experiment substantially reduced.

A copper-gold ore from Xizang grades 0.50% Cu and 0.24 g/t Au, in which chalcopyrite as the dominant copper mineral is finely disseminated. It was proposed that a stepwise flotation process be employed to process this ore. At the first-stage roughing, a non-polar collector CM-2 was adopted under low-alkaline conditions to recover those easily floatable copper and gold minerals, and at the second-stage roughing, Z-200 was adopted to enhance copper flotation effect, so as to improve the recovery rates of copper and gold. A closed-circuit experiment yielded a copper-gold concentrate grading 22.33% Cu and 9.96 g/t Au at the corresponding recoveries of 90.57% and 79.83%, respectively. Compared to high-alkaline flotation processes with ethyl xanthate or Z-200 as collectors, this stepwise flotation process can increase gold recovery by more than 10 percentage points. This technical process can not only avoid depression effect of lime on gold minerals, but also strengthen the collecting effect of copper and gold minerals, thus achieving efficient resource recovery. This study can provide a reference for exploitation and utilization of similar ores.

Based on the characteristics of the exploration contracts approved by the International Seabed Authority (ISA), the global competition status and variation trend of the exploration contract areas are analyzed in terms of temporal changes, spatial distribution and mineral types. Based on the analysis results, strategies to cope with the variation in the situation of ISA exploration contract areas are proposed, including commercial companies acting as the main players, strengthening international cooperation with African countries and the Enterprise of ISA, giving priority to exploration of polymetallic nodules, cultivating advantageous contractors and safeguarding the rights and interests of contractors.