Under the current production conditions, the fluorite concentrate obtained from the associated fluorite resources in a mine of Hunan Province has its processing indicators undesirable and fluctuating widely. In view of this technical bottleneck, a new processing technique was developed to recover such kind of fluorite ore for improving the quality of resources. In this technique, a principle of alkaline environment followed by acidic environment was adopted in the cleaning stage, and also the middlings obtained from the cleaning stage are returned to be processed again. As a result, a full-process closed-circuit test yielded 13.67% high-grade fluorite concentrate grading 96.11% CaF₂ at 60.13% recovery, and 3.93% low-grade fluorite concentrate grading 85.08% CaF₂ at 15.34% recovery. The comprehensive concentrate has a CaF₂ grade up to 93.65%, with total recovery of 75.47%. It is concluded that this low-grade associated fluorite ore can be efficiently and comprehensively recovered using this technique.

In an experiment, oxidative precipitation method was adopted to remove iron from crude nickel sulphate solution. With H₂O₂ or Cl₂ as oxidant, Fe²⁺ in the solution was oxidized to Fe³⁺, and then Fe³⁺ was precipitated in the form of Fe(OH)₃ and FeOOH by adjusting the pH of the solution. It is found that under the optimum conditions for iron removal with H₂O₂ as the oxidant, including H₂O₂ dosage of 3.84%, temperature of 75 ℃, pH of 4.5, dropping of H₂O₂ solution at a rate of 0.33 mL/min, and the aging time of 90 min, the removal rate of iron can reach 99.74%. Under the optimal conditions for iron precipitation with Cl₂ as oxidant, including reaction temperature of 70 ℃, pH of 4.5, Cl₂ injection time of 60 min and aging time of 90 min, the iron removal rate can reach 99.72%. It is shown that the solution after iron removal with H₂O₂ or Cl₂ as an oxidant can have the iron content therein up to the class I standard (iron content no more than 0.000 5%) in GB/T 26524—2023 Refined Nickel Sulfates.

Effect of annealing temperature on the mechanical properties and fatigue properties of Al-Cu-Mg-Ag alloy was explored by preforming fatigue crack propagation (FCP) rate testing, room-temperature tensile test and using characterization means such as X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the T4 state specimen annealed at 420 ℃ for 4 h presents higher yield and tensile strength, but poor plasticity. As the annealing temperature increases within the range of 400－430 ℃, the orientation density of the Goss texture in the alloy first increases and then decreases, and the T4 specimen after 4 h annealing at 420 ℃ presents an optimal fatigue performance, with lower FCP rate around 1.34×10^－3 mm per cycle at ΔK≈20 MPa·m^0.5.

With bamboo as a raw material, different hard carbon materials were prepared by different impurity removal processes, and the effects of those processes on the impurity content, physical structure and sodium storage performance of hard carbon were explored. The results show that after impurity removal treatment, the bamboo-derived hard carbon has reduced impurity content and specific surface area, and increased interlayer spacing. With the preparation cost and the sodium storage performance of hard carbon comprehensively taken into consideration, acid leaching is chosen as the impurity removal process for hard carbon. It is shown that at a current density of 30 mA/g, the anode material with prepared hard carbon can have an initial Coulombic efficiency of 83.87% and a reversible specific capacity of 308.96 mAh/g；it demonstrates a capacity retention rate of 96.57% after 100 cycles at a current density of 300 mA/g, showing excellent sodium storage performance.

To address the problems of poor fluidity and high viscosiy, ore rocks and higher ore losses and dilution due to the influence of moisture content on eastern stopes of Jinshandian Iron Mine, the variation laws of fluidity of ore blocks, shape characteristics of drawn ore blocks, as well as loss and dilution indices of two types of ore bodies in the eastern stopes under influence of different moisture content were analyzed by preforming physical tests and numerical simulation. A reasonable range of drift spacing for the eastern stopes was determined, which was then optimized from the perspectives of safety, technology and economy, based on the improved CRITIC-TOPSIS evaluation method. The results show that with the moisture content in a range of 0－8%, the drawn ore blocks in the eastern stopes are in a shape of an “inverted water drop”, and become shallow as the moisture content increases; with the moisture content in a range of 4%－8%, the natural angle of repose of ore rocks increases with the increase of moisture content, the recovery rates of those two ore bodies are negatively correlated with moisture content, and present an upward trend followed by a decline as the drift spacing becomes wider, while the dilution rate follows the opposite trend. With the moisture content at 6% on average, the optimal drift spacing in the eastern stopes of Jinshandian Iron Mine should be set at 15 m.

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.

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.

Effects of quenching and tempering at different temperatures on the microstructure and hardness of annealed W6Mo5Cr4V2 steel were studied by means of OM, SEM, XRD analysis and hardness test. The results show that the microstructure of quenched W6Mo5Cr4V2 steel is mainly composed of martensite, MC carbide rich in V, W and Mo, and M₆C carbide rich in W and Mo, as well as residual austenite. As tempering temperature rises, the carbide in the microstructure of W6Mo5Cr4V2 steel grows in size, and the hardness decreases after an initial increase. After quenching at 1 160 ℃ plus three times of tempering at 540 ℃, W6Mo5Cr4V2 steel has its carbide become smaller and evenly distributed, and its residual austenite almost eliminated, showing the hardness up to 64.2HRC.

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.

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.