The occurrence state of key elements of niobium, rare earths, and titanium in Bayan Obo niobium concentrate samples was characterized before and after hydrogen reduction, and effect of hydrogen reduction condition on iron metallization rate was also explored. After 90 min reduction with flow rate of hydrogen at 300 mL/min, and reduction temperatures of 800 ℃, 850 ℃, 900 ℃, 950 ℃, 1 000 ℃, and 1 050 ℃ respectively, the corresponding metallization rates are 89.22%, 85.79%, 82.50%, 80.52%, 72.15%, and 70.64%. It is found that during hydrogen reduction process, most of iron minerals can be reduced to metallic iron, but with temperature rise, the reduction rate of iron minerals decreases due to effect of mineral powder bonding. Niobite, as the main niobium-containing phase, is easily reduced, while aeschynite and niobium-iron rutile are difficult to be reduced; bastnasite, the main rare earth-containing phase, doesn't change, while monazite can undergo thermal decomposition at 1 050 ℃; ilmenite, niobium-iron rutile and aeschynite, as the main titanium-containing phases, are difficult to be reduced.

In order to explore the overall stability of slope before and after local failure, as well as the effect of excavation method on slope stability, the slope project on the north side of Jingxi-Barak mining area in Jinchuan of Xinjiang was taken to study local failure characteristics of slope and slope stability under different excavation state by adopting distinct element method. It is found that the distribution of the maximum main stress has a great impact on the slope stability, and the factor of safety for slope stability tends to decrease first and then increase from the stage before local failure to the stage after failure; with more excavated benches, the factor of safety for slope stability tends to increase first and then decrease; with the excavated benches more than 1, the overall factor of safety of the slope meets the requirements; with slope angle less than or equal to 60°, the overall factor of safety also meets the requirements, and the suitable slope angle is 60°.

Al-Cu-Mg-Ag alloy melt was treated with ultrasonic waves, and the effect of the ultrasonic melt treatment on the microstructure and hardness of alloy was investigated. The results show that compared to the as-cast alloy without ultrasonic treatment, the as-cast alloy after ultrasonic melt treatment for 90 s and 180 s respectively has its hardness correspondingly improved by 12.7% and 11.2%. The ultrasonic melt treatment can reduce the segregation of alloy composition and accelerate precipitation of Ω phase during 2 h aging process at 200 ℃. A quantitative analysis shows that ultrasonic melt treatment can reduce the grain size of as-cast alloy, but presents limited effect of fine grain strengthening. Solid solution strengthening and precipitation strengthening respectively improve the hardness of as-cast and T6-tempered alloys.

An experimental research was carried out on leaching of marine sedimentary manganese deposit from Xinjiang, and effects of acid-to-ore ratio, leaching temperature, leaching time, and ore particle size on manganese leaching rate were investigated. The results indicate that effective separation between elements of silicon and manganese in the solution can be actualized by increasing leaching temperature and prolonging leaching time, which can also benefit the formation of large-particle precipitates and enhancement of filtering speed. After manganese ores with particle size of -150 μm are leached at room temperature for 4 hours, with acid-to-ore ratio of 0.56, the manganese leaching rate can be up to 86.32% and a leaching residue rate is 61.12%, while the mass concentration of manganese ions in the manganese sulfate leachate is 41.29 g/L.

An experimental research was performed on pre-enrichment of a weathered low-grade vanadium-bearing stone coal ore to solve the problems of complex flow and high cost for the existing direct vanadium-extraction process. The process mineralogy study shows that the predominant vanadium minerals in the stone coal ore are vanadium-bearing limonite and vanadium-bearing mica, both being weakly magnetic, and a superconducting magnetic separation (SMS) plus sedimentation process is proposed for pre-enrichment of vanadium. With magnetic field strength of 4 T and slurry flow rate of 8.0 L/min, SMS produced a pre-enriched concentrate with V₂O₅ grade of 1.44% at a recovery of 55.08%. The SMS tailings were then subjected to sedimentation and classification to further recover vanadium, leading to the final concentrate with V₂O₅ grade of 1.03% and recovery of 79.48%, presenting that 59.02% tailings were discarded. With this pre-enrichment process, vanadium in the stone coal ore can be efficiently reclaimed, which meets the requirements for subsequent metallurgical vanadium extraction.

The process and mechanism of removing iron ions from manganese leaching solution by a combination of pyrite and air were explored. The results show that after iron removal by 1 hour of reaction at 25 ℃, with pH of solution at 2.5, addition of pyrite at an amount of 15 g/L, and air flow rate at 2.4 L/min, the left leaching solution has a mass concentration of residual iron ions less than 0.01 g/L, and the manganese recovery rate is higher than 99%. Pyrite as a reducing agent, in combination with air in the solution, creates an active reaction zone around pyrite with the coexistence of Fe³⁺/Fe²⁺ with oxygen, which contributes to the precipitation of iron ions in the form of goethite in the solution for removal.

The chemical composition, types and content of minerals, microregion quantitative energy spectrum analysis of titanium-bearing minerals, equilibrium estimate of TiO₂, occurrence state of titanium-bearing minerals, particle size and dissociation degree of ilmenite in a vanadium-titanium magnetite ore from Panxi region have been investigated. By these means, the reasons for difficulty in this ore dressing were ascertained. The technical index of ilmenite concentrate and the main mineralogical factors affecting the ilmenite dressing effect have been analyzed comprehensively, which may provide a detailed scientific basis for development and utilization of this vanadium-titanium magnetite ore in Panxi region.

The stability of goafs in a mine was analyzed. Firstly, the current situation of the goafs was investigated in detail to clarify the distribution and volume of goafs. Secondly, the stability variation of goafs before and after backfill was evaluated based on the FLAC^3D simulation results. It is found that there are five main goafs in the mine, which are distributed in the middle section of 700-860 m, with total volume of around 404 500 m³. Currently, the roof of goaf is unstable, posing a greater potential risk of collapse. The rock mass that is not connected together from 1^# to 4^# goaf has concentrated force on it and a plastic zone penetrates through, possibly causing large-scale instability. After the goafs in the middle section of 700-820 m are gradually backfilled, the risk of goaf instability can be gradually eliminated, and production activities in the middle section below 700 m won't be affected. It is recommended that 1^#-4^# goafs should be preferably backfilled to reduce the risk of roof collapse and penetration.

The effect of Sc on the microstructure and properties of Al-8.5Zn-2.3Mg-2.4Cu alloy was investigated. It is found that an addition of Sc can make the as-cast Al-Zn-Mg-Cu alloy with obviously smaller grain. As the Sc content (mass fraction) increases from 0 to 0.4%, the grain size of alloy decreases from 107.7 μm to 49.96 μm and the hardness increases from 116.8HV to 130.2HV. After hot-rolling process with large deformation quantity followed by 1 hour of solution heat treatment at 470 ℃, the Sc-containing alloy has higher dislocation density compared to the alloy without Sc addition, and the alloy with an addition of 0.4% Sc has a recrystallization rate dropped from 92.4% to 45.7% due to inhibition of its recrystallization behavior. After 24 hours of aging treatment at 120 ℃, the Al-Zn-Mg-Cu alloy with an addition of 0.4% Sc can be observed to have a large amount of spherical Al₃Sc particles and short rod-like η′ (MgZn₂) particles in dispersive distribution. Based on the plotted a crystal structure of Al₃Sc-MgZn₂ with coherent or semi-coherent interface with α (Al), it can be deduced that the Al₃Sc particles provide heterogeneous nucleation sites for η′ (MgZn₂) phase to promote its nucleation, which can promote precipitation hardening of the alloy.

In order to know the status quo of technologies for deep-sea mineral resources development, the related patents were briefly analyzed. A total of 3 236 patents regarding deep-sea mineral resources development technologies published worldwide from 2000 to 2023 were taken from the incopat global patent database, and analyzed in terms of number of patent applications, geological distribution, subdivision of technologies, time of Chinese patents applications, as well as nationalities of Chinese patent applicants among others. It is found that the patents regarding deep-sea mineral resources development are mainly from China, United States, Korea, Russia and Japan, focusing on technologies including detection system, mining system and transportation system. In recent years, Chinese patent applicants have gradually predominated in the related patent application worldwide, reflecting China's great potential in R & D and market expansion of deep-sea mineral resources development technologies.