A new short-process preparation technique for battery-grade iron phosphate was explored with iron powder and phosphoric acid as main raw materials. The effects of iron powder dissolution mechanism, iron phosphate reaction conditions, and mother liquor recycle on product indicators were investigated. The results show that the dissolution rate of iron powder can reach 97.92% at a temperature of 70 ℃, with phosphoric acid at a concentration of 20%, iron and phosphorus at a ratio of 1/3, and iron powder at a size of 150 μm；after 1 h precipitation at 100 ℃, with an addition of hydrogen peroxide at 110% of the theoretical amount, an iron phosphate with D₅₀ of 2 μm was prepared with the precipitation rate of 98.86%. The obtained iron phosphate has stable crystal form with uniform crystal grains, and the contents of elemental impurities are significantly lower than the requirements specified in the HG/T 4701—2021 standard. The precipitated mother liquor in the process can be recycled, leading to actualization of low-carbon and green production.

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.

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%).

With the red mud from Guizhou as raw material, an experiment was carried out by adopting a process of low-temperature acidification roasting followed by water leaching to recover scandium, and effects of factors, including sulfuric acid dosage, temperature and time for roasting process, liquid-solid ratio of leaching solution, leaching temperature and time, on scandium leaching rate were investigated. It is shown that after 4 h-roasting at 200 ℃ with sulfuric acid and raw ore in a mass ratio of 1∶1, and then 4 h-leaching at 80 ℃ with leaching solution and solid in a mass ratio of 6∶1, the leaching rate of scandium can be finally up to 89.10%.

An experiment was carried out on treating high-salinity wastewater by air gap membrane distillation (AGMD). Effects of different operating conditions on the performance of AGMD were investigated, and membrane fouling and its control measures were also analyzed. It is shown that the permeation flux increases with the increase of temperature and flow rate of feed, and decreases with the increase of cooling water temperature and salt concentration. The salt rejection rate can maintain above 99.8% with the salinity less than 60 g/L, and still exceed 90% with salinity within the range of 60－100 g/L. It is concluded that AGMD technology can be adopted to treat high salinity wastewater.

To explore the impact of near-surface ore body mining on the stability of overburden and dangerous rock masses of slopes, a phosphate mine was taken as an engineering project in the study. The stability of the dangerous rock mass of the slopes was determined by on-site investigation, and the evolution of deformation, stress and plastic zone of overburden under different mining schemes were simulated with FLAC^3D software. The research results indicate that structural planes between layers of surrounding rock on the roof of stope are well-developed, probably causing falling debris in blocks or flakes. The strata are hard and brittle in lithology and have developed rock fractures. Under unloading effect of high and steep slopes, dangerous rocks are prone to be separated along the combination of fractures and strata plane, forming dangerous rock masses. The response law of the maximum stress in the overburden is similar to the law of the unbalanced force in numerical calculation. There is relatively small disturbance generated during mining process, which brings a little impact to the stability of adjacent stopes and surface. It is found that the ground surface is less affected by underground mining, with the deformation within the maximum limit value specified in the standard. If Ph2^# ore body is mined after Ph1^# ore body, the overburden can have relatively small displacement, and no connectivity in the plastic zones is occurred in the mining pillars, stopes and overlying strata.

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.

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.

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.