The effect of water splat cooling assisted friction stir welding (WCaFSW) on the structure, texture and mechanical properties of aluminum alloy welding joints were investigated by means of optical microscopy, scanning electron microscopy and a tensile testing machine. The results show that compared to normal friction stir welding (FSW), WCaFSW can lead to grains in weld nugget zone (WNZ) with significantly reduced size and grains in all regions of WNZ with more uniform size, and a higher percentage of high-angle grain boundaries. The WNZ of FSW joints have and B shear texture, while the WNZ of WCaFSW joints have and C shear texture. Compared to FSW joints, WCaFSW joints have higher tensile strength and lower elongation rate. And ductile fracture is the main failure mode in both WCaFSW and FSW joints.

High-strength and high-conductivity Al-0.65Mg-0.58Si-0.17Fe alloy wire was prepared by adopting horizontal continuous casting process followed by continuous extrusion and drawing processes, and effects of such processing technique and heat treatment on microstructure, mechanical properties and conductivity of the prepared alloy were investigated. The results show that the processing technique of horizontal continuous casting plus continuous extrusion can improve the solid solubility in supersaturated alloy and lead to significantly grain refinement, and the following drawing process introduces high-dense dislocation, which changes the precipitation behavior of Mg₂Si phase during the ageing treatment of the alloy. It is shown that Al-0.65Mg-0.58Si-0.17Fe alloy prepared by the processes of horizontal continuous casting, continuous extrusion and drawing is subjected to 3 hours of aging treatment at 155 ℃, resulting in its tensile strength of 335 MPa, elongation rate of 6.9%, and electrical conductivity of 55.7%IACS.

The expanded graphite (EG) derived from the graphite anodes of spent lithium-ion batteries was taken as conductive substrate, and then Sn/Co-based bimetallic sulfide was loaded by using a hydrothermal method to synthesize SnCoS₄@EG nanocomposite. And such EG presents a cross-linked porous three-dimensional lattice, and the SnCoS₄ nanocrystals in the synthesized composite are uniformly dispersed in the EG, which enhances electrical conductivity of electrode material and stability of metallic sulfide, but also increases the contact area between active sites and electrolyte, leading to a higher exchange rate of Li⁺ ions at electrode/electrolyte interface. It is shown that SnCoS₄@EG electrode can exhibit a reversible specific capacity of 1 195.90 mAh/g at 1.0 A/g after 500 cycles, presenting excellent durability over a large number of cycles.

In order to improve the strength-ductility balance of medium manganese steel for automobiles, cold-rolled medium manganese steel was treated by annealing at different temperatures (650-680 ℃) and for different time (10-50 min) for austenitic reverse transformation. Then, effects of annealing temperature and holding time on the microstructure and mechanical properties of medium manganese steel were explored. It is found that the microstructure of the original cold-rolled medium manganese steel plate is composed of ferrite (F) and martensite (M), and the dispersed carbides with sizes ranging from 20 nm to 45 nm can be observed in the microstructure. As the annealing temperature rises from 650 ℃ to 680 ℃, the yield strength, elongation, strength-ductility balance, and residual austenite volume fraction of medium manganese steel increase followed by a decrease, but tensile strength increases all the time. As the annealing time is prolonged from 10 min to 50 min, the yield strength, tensile strength, elongation, strength-ductility balance and residual austenite volume fraction of medium manganese steel decrease after an initial increase. It is found that after annealing treatment at 660 ℃ for 30 min, the cold-rolled medium manganese steel has a structure composed of F + M + austenite (γ), with austenite at a volume fraction of 24.12%, ultrafine grained ferrite with an average grain size of 0.29 μm, lath martensite with an average wideness of 0.27 μm, and strength-ductility balance of 23.33 GPa·%.

An iron concentrate obtained from magnetic separation of red mud from Shandong was used in an experimental study on the effect of titanium removal by reverse flotation. In the experiment, with sodium oleate as collector, corn starch as hematite depressant, sulfuric acid as pH regulator, pulp pH of 9, and the addition of corn starch and sodium oleate at an amount of 500 g/t and 1 500 g/t, respectively, the iron concentrate was produced, with the TiO₂ grade fell down from 6.90% to 2.73%, and the TFe recovery reaching 41.80%. The results of collector adsorption and IR analysis show that sodium oleate exhibits selective adsorption characteristics, which has further confirmed the feasibility of sodium oleate used in removing titanium by reverse flotation of iron concentrate obtained from magnetic separation of red mud.

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.

To investigate directional independence of multistage stress memory during progressive cyclic loading of granite under compression with a series of deflection angle, experiments were conducted on cyclic loading and unloading of granite with different deflection angles by using a self-made deflection device. The Kaiser effect (KE) and the incomplete erasion phenomenon (IEP) of the maximum stress in previous multistage cycles after progressive cyclic loading with deflection angles were explored in the experiments. Results show that both KE and IEP in granite exhibit directional independence. The directional independence of KE has a critical angle of 10° and the directional independence of IEP has a critical angle of 12°. With a deflection angle of 12°, the IEP will interfere with the memory of historical maximum stress by KE.

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.

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.

Copper ore sorting by dual-energy X-ray technique basded on traditional algorithms by curve fitting of T-value always results in great deviation. In view of this problem, a curve fitting of T-value by segmented straight lines was proposed. This method divides thickness into several segments, and performs a T-value curve fitting in each segment for copper ore sorting, which can more accurately reflect the changing trend of T-value with different thicknesses and also reduce impact of thickness on sorting. High-energy and low-energy rays are adopted to fit the T-value curve, and then the residual between the T-value and the curve-fitting mapping value is calculated in each segment, showing different residuals for different substances, which can be used to achieve copper ore sorting. In a verification experiment, two types of copper ores with different grades were sorted by this method. The ore images fitted with T-value curves by segmented straight lines were put into ResNet18 neural network for training, and the trained model was then used for testing. The test results show that an accuracy rate can reach 88.67%.