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.

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.

In order to effectively predict blast-induced rock fragmentation, a distribution of normalized rock fragmentation under different conditions was obtained by performing a designed experiment on drilling and blasting of a concrete specimen, and then the rock fragmentation exceeding 40 mm was selected for study. The correlation among variables under different testing conditions was analyzed by using Spearman correlation statistics, and the initial weights and thresholds of the BP neural network were optimized by using the ant colony optimization (ACO) to construct an ACO-BP model. The model was then trained with rock fragmentation by on-site blasting, and tested. Based on the comparison of such prediction mode with BP neural network model, random forest (RF) model and extreme gradient boosting (XGboost) model, it is found that the ACO-BP model is highly reliable in predicting blast-induced rock fragmentation, presenting a root mean square error of 0.13, an average absolute error of 0.11, and a coefficient of determination of 0.92. It is concluded that this model, with higher accuracy in prediction and applicability, can accurately predict blast-induced rock fragmentation.

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.

In order to analyze mechanical properties of conveying hose during deep-sea mining operation, a mechanical model was established with Abaqus software for the buffer, flexible hose, and mining vehicle under different working conditions to analyze effects of buoyant ball position, buoyant force, ocean current velocity and volume fraction of conveyed mineral ores on hose configuration, as well as effect of forces that flexible hose exerts on the mining vehicle. When buoyant balls are put on the position far away from a mining vehicle, the hose is prone to be dragged on the seafloor；while being closer to a mining vehicle, the hose is prone to be entangled. It is shown that the closer to a mining vehicle, the greater the buoyant force and the greater the forces that the hose exerts on the mining vehicle. Furthermore, slower current velocity is more likely to bring greater impact to the hose configuration. The velocity of ocean current will influence the direction, magnitude and variation of the forces exerted on the mining vehicle. It is suggested that with ocean current at a velocity of 0.2 m/s, buoyant balls should be put on the position 12 m away from the buffer, with buoyant force selected at 1 500 N. In this case, the maximum horizontal and vertical tensile forces of the hose on the mining vehicle are 941 N and 1 258 N, respectively.

In order to balance productivity against safety in the mining of high-level stope with gently-dipping and extrathick orebody, an iron mine adopting sublevel open stoping with backfill was taken as an example to optimize the mining sequence. Firstly, pillars was determined to at a reasonable spacing from 14.2 m to 47.2 m based on the theory of bearing capacity of pillars. Secondly, according to stope structure parameters, the pillars were designed to be 15 m, 30 m and 45 m in thickness, respectively. An orebody model was also established with FLAC^3D and then was used to analyze the roof subsidence and pillar stability based on comparison of each mining scheme. Finally, a judgment matrix of mining sequence was constructed based on analytic hierarchy process and fuzzy comprehensive evaluation method, with both factors of safety and productivity taken into consideration in the numerical simulation. The comprehensive membership degrees of those three schemes were calculated to be 0.86, 0.79 and 0.80, respectively, and pillars in the best scheme were determined to be in the thickness of 15 m. The results of an industrial experiment have proven that this scheme can ensure stope with relative stability while achieving the maximum production capacity.

In order to address the problem of slope stability for a valley dumpsite in one mountain area, numerical simulation was conducted with FLAC^3D for the stability of slope under three working conditions, including natural state, rainstorm case and earthquake occurrence. The stability and reliability of the dump under conditions of rainstorm plus seismic was evaluated with introduced Monte Carlo algorithm. Results show that the overall and part of dumpsite slope, under all three working conditions of natural state, rainstorm and earthquake, can be in a stable state, and the overall safety factors present a normal distribution and are mainly within the range of 2.0-2.1, consistent with the numerical simulation results (2.08); under conditions of rainstorm plus seismic, the probability for the overall dumpsite to be unstable is 0, while some parts of dumpsite have a 35.99% probability to be unstable. It is shown that the numerical simulation value and on-site monitoring result present a deviation from 9.8% to 15.4% based on the comparison.

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.

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 effects of separate and combined usage of NaClO and KMnO₄ on the flotation separation of chalcopyrite and pyrite were investigated by performing flotation and adsorption tests, infrared spectroscopy (IR) and XPS analysis. The results show that selective separation of chalcopyrite and pyrite can be achieved with NaClO and KMnO₄ in a ratio of 10∶1, the total oxidant dosage of 70 mg/L, pulp pH of 10, and oxidation time of 3 min. It is shown that the recovery of chalcopyrite can exceed 92%, while the recovery of pyrite is less than 8%. The IR and XPS analyses show that a combined usage of NaClO and KMnO₄ obviously changes the surface property of pyrite, resulting in hydrophilic oxidized substances on the surface, such as iron oxide, iron hydroxide and iron sulfate, which impedes the adsorption of collectors, thus reducing floatability of pyrite. The chalcopyrite surface remains mildly inert to NaClO and KMnO₄ under certain conditions. Consequently, the adsorption of xanthate on chalcopyrite is remarkably higher than that on pyrite, which favors their flotation separation.

According to the mineral properties of a kind of flake graphite ore in Heilongjiang Province, a new efficient flotation reagent was developed and then adopted in a flotation experiment. Results show that with the new reagent of CYM-11 as a collector, CYQ-01 as a foaming agent, an experiment with a closed-circuit flowsheet consisting of eight-stage regrinding and nine-stage cleaning can yield an graphite concentrate with fixed carbon content of 96.63% at 95.69% recovery, among which the graphite concentrate at a size of +0.15 mm can be produced with a yield of 11.38% and fixed carbon content of 96.04% in mass fraction. It is shown that the large flake graphite can be well protected during the course of mineral processing.

To explore feasibility of replacing steel ball with porcelain ball in the second-stage grinding of a magnetite ore from Anhui, the feed ore to the second-stage grinding process in the magnetite ore processing plant was taken for study, and single-factor tests were conducted for gradation of porcelain ball in diameter, grinding concentration and filling rate of grinding media. On this basis, researches on grinding kinetics and commercial application were also conducted. The results show that porcelain ball can substitute steel ball as the medium in the second-stage grinding, which can bring in optimized particle size distribution of the milled product. For the feed in a particle size greater than 0.092 mm, the grinding rate of porcelain ball milling is greater than that of steel ball milling；while with the feed in a particle size less than 0.092 mm, the grinding rate of porcelain ball milling is less than that of steel ball milling. The best conditions for porcelain ball milling are finally determined as follows: porcelain balls with diameter of 30 mm, 25 mm and 20 mm in a mass ratio of 1∶3∶1, grinding concentration of 74% and grinding media with filling rate of 40%. The industrial applications with porcelain ball in mill shows the particle size distribution of overflow products can be effectively improved, both unit power consumption and ball consumption reduced by 51.89% and 50%, respectively.

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%.

An experimental study was performed on efficient separation of talc and molybdenite by adopting flash flotation. With grain fineness of 0.043-0.074 mm, 20 g/t of frother MIBC, and flotation time of 60 seconds, the talc recovery attains 76.64%, while the recovery of molybdenite is only 19.72%, resulting in an efficient separation between talc and molybdenite. According to the nonlinear fitting of flotation kinetic equation by MATLAB, talc flotation process conforms to the classic first-order flotation kinetic model, while molybdenite flotation conforms to the modified classic first-order flotation kinetic model. The following test on the influence of flotation time on adsorption of MIBC on talc and molybdenite shows that talc is more likely to interact with the agent than molybdenite at the early stage of flotation, and much more MIBC is adsorbed on talc than on molybdenite at that stage.

In order to utilize low-grade associated cassiterite resource from Huangshaping polymetallic ores, a new beneficiation process consisting of high-gradient magnetic separation (HGMS) for tailings discarding and tungsten-tin flotation for enhanced enrichment was developed based on the performed HGMS and flotation tests. After HGMS to pre-discard tailings, the loss rates of molybdenum, tungsten and fluorite were all less than 10%, while cassiterite was greatly enriched in the HGMS rough concentrates. Then, a flotation of reground HGMS rough concentrate was conducted by using Pb-BHA-SPA multiple ligand metal-based collector, producing a mixed tungsten-tin concentrate grading 0.627% WO₃ and 0.78% SnO₂, at corresponding recovery of 26.56% and 18.03%, respectively. This process provides a new idea and method for enhanced enrichment and effective utilization of low-grade associated cassiterite.

Based on the detailed process mineralogy study of a kind of refractory gold ore, an experimental research was carried out for gold extraction. It is found that the gold mineral in such ore are fine-grained and dispersed in gold-carrying minerals. It is proposed that such refractory gold ore be processed with the technique of enhanced flotation, and an addition of regulator XPT511 can effectively improve the index of gold flotation. It is shown that a close-circuit flotation test results in a gold concentrate grading 22.91 g/t Au at 62.85% recovery.

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.

Copper slag flotation tailings were taken as raw materials, and carboxymethylcellulose (CMC), bentonite, sodium silicate alone or the mixture were taken as binders to prepare copper slag pellet for reducing dust and flue gas generated during utilization of copper slag tailings. The effect of binder on balling was explored in terms of the drop numbers, compressive strength and cracking temperature of green ball, and microscopic morphology, adsorption characteristics and surface potential changes were also analyzed by scanning electron microscopy, infrared spectroscopy and Zeta potential detection. Results show that all three binders can be useful in agglomeration of copper slag tailings. When used alone, CMC, bentonite and sodium silicate are required to be added at an amount more than 0.20%, 2.0% and 2.5%, respectively. In case of CMC used in combination with bentonite or sodium silicate, bentonite or sodium silicate should be added at an amount of more than 2.0% and more than 2.5%, respectively, with the addition of CMC is at an amount of 0.1%；while with the addition of CMC at an amount of 0.15%, the addition of bentonite or sodium silicate should be more than 1.5% and more than 2.0%, respectively. With the addition of binder, the prepared pellet has more compacted structure and stronger spatial structure. It is found that copper slag tailings particles have a lower value of zeta potential, and an improved hydrophilicity, which can promote interparticle adsorption, and thus improves pellet quality.

The acid leaching solution of cathode materials from spent lithium iron phosphate batteries was taken as raw material, and iron, phosphorus and lithium elements therein were recovered by adopting an oxidation-precipitation process. The effects of factors, including endpoint pH value of reaction system, reaction temperature, concentration of sodium hydroxide, dripping rate of sodium hydroxide, and the volume ratio of hydrogen peroxide to acid leaching solution, on the precipitation rates of iron and phosphorus and the loss of lithium during the precipitation process were all investigated. Results show that with the endpoint pH value of 2.5, temperature of 75 ℃, sodium hydroxide with concentration of 1.5 mol/L, sodium hydroxide solution at a dripping rate of 7.7 mL/min, and hydrogen peroxide and acid leaching solution in a volume ratio of 1∶60, the average precipitation rates of iron and phosphorus are 99.86% and 98.23%, respectively, and the average loss of lithium is just 1.23%. Under the above-mentioned conditions, iron and phosphorus in the solution can be effectively removed and recycled in the form of iron phosphate, presenting a lower loss rate of lithium. After 5 h-heat treatment at 700 ℃, it is shown that the chemical composition of iron phosphate can meet the industrial standard.

In order to find a reasonable disposal method for electrolytic manganese slag (EMS), effect of roasting at medium and high temperature on the content of manganese, sulfur and ammoniacal nitrogen in EMS was explored. The results show that after the EMS is directly roasted at 1 050 ℃ for 60 min, the mass fraction of S in the EMS sample falls from 9.11% to 0.87%, while the mass fraction of Mn goes up from 1.87% to 2.26%. After being washed with water, the EMS sample is then roasted with 3% coal (in mass fraction) at 1 000 ℃ for 60 min. As a result, the mass fractions of S and Mn in the obtained roasted sample drop down to 1.32% and 0.78%, respectively. It is found that after direct roasting process at medium and high temperature, EMS can meet the requirement of mass fraction of S for cement admixture, and also medium and high temperature roasting process can almost remove all ammoniacal nitrogen therein, presenting a good removal effect.

A heap leaching test was carried out for the low-grade copper-cobalt oxide ores from Congo (DRC), and effects of spray intensity, spray acidity and ore particle size on the leaching rates of copper and cobalt were investigated. The results show that both acidity and intensity of spray bring significant impact to the speed and cumulative rates of copper and cobalt leaching, while the ore particle size has little effect on leaching process. And finally, the optimal conditions for heap leaching of low-grade copper-cobalt ore were determined, including spray acidity at 20 g/L, spray intensity of 15 L/(m²·h), and ore particle size of less than 40 mm. It is shown that the cumulative leaching rates of copper and cobalt can reach 90.89% and 82.27%, respectively, after 100 days of heap leaching.

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.

Nickel, Cobalt and Manganese in the cathode materials of spent ternary lithium-ion batteries were recovered by leaching with a combination of citric acid and hydrogen peroxide. The possible reactions during the leaching process were analyzed, and the effects of factors, including citric acid concentration, mass fraction of hydrogen peroxide, leaching temperature, leaching time and liquid-to-solid ratio on the leaching rates of nickel, cobalt and manganese from cathode materials were also investigated. It is found that after 60 min leaching at 80 ℃ with citric acid at a concentration of 1.5 mol/L, hydrogen peroxide at a mass fraction of 8%, and a liquid-to-solid ratio of 25 mL/g, the leaching rates of nickel, cobalt and manganese are 97.58%, 97.35% and 96.12%, respectively. Then, an antisolvent crystallization method is adopted with ethanol as antisolvent agent to recover metals from the obtained leach liquor, leading to the crystallization rates of nickel, cobalt and manganese at 92.34%, 93.07% and 99.69%, respectively.

An experiment was carried out with a pelletizing and magnetization roasting process for fine-grained specularite to investigate the pelletizing process, as well as the roasting performance and effect of pellets in the process of magnetization roasting. The results show that by adopting a process of fine grinding and pelletizing followed by magnetization roasting with an additionally prepared reducing agent, under the condition of roasting at 810 ℃ for 60 min, and addition of charcoal at an amount of 2.5%, a concentrate grading 49.04% Fe at 76.99% recovery can be obtained. In comparison, with a process of direct pelletizing followed by 60 min magnetization roasting at 650 ℃ with additionally prepared reducing agent and addition of semi-coke at an amount of 3.0%, the concentrate grading 52.95% Fe at 85.07% recovery can be obtained. It is found that the processing technique consisting of direct pelletizing and magnetization roasting is simpler and can bring better processing indicators. It can provide a reference for on-site processing of fine-grained specularite by adopting magnetizing roasting.

A cyanide-free leaching test was performed for the arsenic-carbon bearing gold ore from Laos, and effects of grinding fineness, pH value of pulp, concentration of slurry, and the dosage of golden cicadas environment-friendly leaching agent for gold on gold leaching effect were investigated. The results show that pre-treatment with hydrogen peroxide can improve the leaching rate of gold. With a grinding fineness of -0.074 mm 95% and an agitating speed of 2 000 r/min, the pulp is pre-oxidized with 500 g/t of hydrogen peroxide for 3 h, and then treated by 30 h agitation leaching with addition of lime at an amount of 3 000 g/t and golden cicadas environment-friendly leaching agent for gold at 5 000 g/t, leading to the residue grading 0.25 g/t Au and gold leaching rate of 92.27%. It is shown that this pretreatment with hydrogen peroxide can make gold leaching rate up by 1.96 percentage points.

An experiment study was carried out on a processing technique of reduction leaching of pyrolusite with acidic wastewater from steel mills as the reductant, for comprehensive utilization of pyrolusite and acidic wastewater of steel mills. The results show that 3 hours of leaching at 90 ℃, with FeCl₂ and MnO₂ in a mass ratio of 2.2, liquid-solid ratio of 11∶1 and the acid wastewater at an initial concentration of 2.5 mol/L, can result in the leaching rates of Mn, Fe and Al from the pyrolusite at 97.14%, 95.37% and 41.33%, respectively. And then, Fe³⁺ in the leachate is reduced with scrap iron at an amount of 1.1 times the theoretical amount at a temperature of 80 ℃ for 50 min, leading to the reduction rate of Fe³⁺ up to 99.85%. After Fe³⁺ is reduced to Fe²⁺, the Fe²⁺-containing reducing solution is returned for leaching again, presenting stable leaching results. It is shown that the average leaching rates of Mn, Fe and Al from pyrolusite are 96.75%, 95.31% and 41.18%, respectively.

Vanadium was extracted from vanadium-containing stone coal by adopting a process of sulphuric acid curing and water leaching, and the effects of sulphuric acid curing and water leaching conditions on vanadium leaching rate were investigated. It is found that the vanadium-containing stone coal is firstly subjected to a sulphuric acid curing process at 130 ℃ for 8 h, with an addition of H₂SO₄ at an amount of 25%；and then the obtained product is leached by water at 90 ℃ for 120 min, with liquid-solid ratio of 2∶1, resulting in the vanadium leaching rate of 90.79%. After the vanadium-containing leachate is oxidized with NaClO₃, the vanadium in the oxidized solution is adsorbed with D202, and then the vanadium in the resin is desorbed. The obtained solution after desorption is subjected to calcination, and vanadium pentoxide is produced with a purity up to 99.21%. It is shown that a total recovery rate of vanadium is 85.99%.

Thermodynamic analysis was conducted with HSC Chemistry 9.0 software for removing arsenic by sulfuration from waste acidic solution left after copper electrolysis, and it is found that H₂S could effectively make asenous acid and arsenate in the high-concentrated sulfuric acid system precipitated by sulfuration. Based on the theoretical analysis results, an experiment on arsenic removal of waste acidic solution by sulfuration was carried out to investigate the effects of sulfurizing agent dosage and reaction time on the arsenic precipitation effect by sufuration. Results show that by 30 min-sulfuration with an addition of H₂S at 0.87 times the theoretical amount, the arsenic content in waste acidic solution after precipitation process falls down to 10.68 mg/L from 6 777.52 mg/L, and the removal rates of arsenic, copper and antimony are 99.84%, 99.76% and 99.33%, respectively. The iron and nickel therein are hardly precipitated, and the mass fraction of arsenic and sulfur in the residue of the arsenic removal process are 43.21% and 44.68%, among which the arsenic in the form of arsenic sulfide is in a mass fraction of 42.33%, and S/As in the arsenic sulfide is in a ratio of 2.29. The finally obtained product is a mixture of As₂S₃ and As₂S₅. It is shown that the thermodynamic analysis results differ slightly from the experimental results, but are still of guiding reference for experiments and practice.

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.

A FeCoCrNiMn high-entropy alloy (HEA) coating was prepared on the 201 stainless steel surface by adopting high-speed laser cladding technology, and then the microstructure, phase distribution, microhardness of FeCoCrNiMn coating, as well as its wear properties in dry sliding condition were all investigated. It is found that such laser cladded FeCoCrNiMn HEA coating consists of a single FCC structure, with no obvious cracks observed. It also forms a good metallurgical bond with the substrate. The microhardness of the coating is around (439±2.1) HV, nearly two times that of 201 stainless steel substrate, and the strengthening mechanisms mainly include strengthening by grain refinement and solid solution strengthening. Also, the FeCoCrNiMn coating presents an obviously better wear resistance than 201 stainless steel, with an average friction factor of 0.246 and a specific wear rate of about 2.59×10^-6 mm³/(N·m). The wear mechanisms for it include adhesive and abrasive wear. It is concluded that such FeCoCrNiMn HEA coating prepared by high-speed laser cladding technology can significantly improve the surface hardness, wear resistance and service life of machine components.

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.

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·%.

In order to investigate the main factors affecting the service life of graphite anodes used in preparation of rare earth metals, a range of analytical tools, including a digital microscope, an optical microscope, an SEM, XRD, a simultaneous thermal analyzer and a four-probe tester were employed for comparison and comprehensive evaluation of macroscopic and microscopic morphology, crystal structure, graphitization, thermal properties and resistances of graphite anodes with different service lives. The results indicate that the resistance, internal cracks and porosity of graphite anodes contribute mainly to the difference in the service life of graphite anodes. The research results can be of reference for selection of graphite anode in preparation of rare earth metals, thus providing technical assistance for enterprises to realize cost reduction and efficiency improvement.

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.

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.

Surface mechanical attrition treatment (SMAT) was adopted for low-carbon steel materials to achieve surface nanonization, and then the influence of surface nanonization on corrosion resistance of low-carbon steel was also discussed. The results show that due to surface nanonization, the low-carbon steel has a greater plastic deformation on the surface as the carbon content decreases, and the X-ray diffraction of its surface presents obviously wider peaks. It is found that after nanosizing treatment for the surface of low-carbon steel with different carbon content, the lower the carbon content, the rougher the surface and the worse the corrosion resistance.