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.

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.

        为了深入交流与展示浆体浓缩与管道输送技术领域的工程经验、科技成果、先进技术、设备及相关信息，深度探讨行业发展趋势和前景，加强各单位及科技人员的技术交流与合作，理论联系工程实际，以成功应用案例为依托，探讨浆体浓缩与管道输送理论、输送工艺与装备技术，数字化和智能化与浓缩输送技术的发展和融合，为浆体管道输送技术的产学研用搭建交流平台，浆体浓缩与管道输送学术委员会、中国金属学会选矿分会、长沙矿冶研究院有限责任公司、陕西神渭煤炭管道运输有限责任公司等拟于2025年10月15~18日，在陕西省西安市举办2025年第六届全国浆体浓缩与管道输送技术与装备研讨会。届时将邀请政府相关部门领导、国内外著名专家以及矿山企业、设备制造公司技术专家进行学术交流与应用案例分析，开展全方位交流与座谈。欢迎国内外浆体浓缩与管道输送技术领域管理人员、专家、学者以及工程技术人员参会交流。现将有关情况通知如下。
一、会议主题  
        数智引领，创新图强，让中国浆体管道通向全球！
 二、会议内容  
        1.精彩报告
        (1)特邀院士、行业精英深度剖析行业现状，预测行业发展趋势；
        (2)学术论文报告、生产技术交流、设备厂家产品介绍；
        (3)标准规范及学术专著现场发布。
        2.技术与装备成果展览
        荟萃全球浆体管道领域头部企业、行业领军供应商与顶尖技术服务商，集中展示浆体浓缩与管道输送技术与装备领域的前沿突破与卓越成就。
        3.参观考察
        参观世界最长、中国唯一长距离的陕煤神渭输煤管道项目及先进耐磨管材展示区。
三、会议主办单位  
        浆体浓缩与管道输送学术委员会
        中国金属学会选矿分会
        长沙矿冶研究院有限责任公司
        陕西神渭煤炭管道运输有限责任公司
        清华大学水沙科学与水利水电工程国家重点实验室
        湖南大学
四、会议时间及地点  
        会议时间：2025年10月15~18日。会期4天，15日全天报到，16~17日会议，18日散会。
        会议地点：陕西省西安市，西安曲江惠宾苑宾馆（西安市雁塔南路388号）。
五、会议征文内容  
        1.管道数字化、智能化与智慧管道；
        2.国内外浆体管道现状与发展趋势；
        3.固液两相流理论与工程应用；
        4.浆体浓缩、脱水技术与装备；
        5.膏体流变学与充填管道输送技术；
        6.国内外浆体管道工程典型案例经验分享；
        7.浆体管道试验、设计以及工程建设技术；
        8.浆体管道测堵测漏、安全监测以及管道工程维护、抢修技术与装备；
        9.浆体管道动力泵、管材和阀门等技术与设备；
        10.深海采矿水力提升技术与装备；
        11.河海疏浚与泥沙管道输送技术；
        12.固废处置与管道输送技术应用；
        13.管道工程仪器仪表与自动检测技术及设备；
        14.管道施工技术与装备；
        15.气固粉体输送及气固液三相流管道输送技术。
        ……
六、会议论文  
        1.论文作者请于2025年7月31日之前将论文通过E-mail发送至论文评审组邹伟生教授处(E-mail:zouweisheng@sina.com)，需适当延缓提交论文的作者请与邹伟生教授联系。会议论文经专家审阅通过后，将以专刊形式出版。
        2.本次征文将由大会组委会指定的全国中文核心期刊《矿冶工程》公开出版。
七、会议报名  
        扫描以下二维码在线报名。
        
        联系人：陈光国13687399397（微信同号）
        周杨15111122546（微信同号）

Extreme high-speed laser cladding (EHLA) technology was used to prepare Al₂O₃-316L coatings on Ti6Al4V rods. The effects of scanning speed, powder feeding rate on single-track coating quality, and 316L powder content on multi-track coating quality and corrosion resistance were explored. Results show that with the following optimum process parameters, including scanning speed of 250 mm/s and powder feeding rate of 8 g/min, the coating can present superior quality with the 316L powder in a mass fraction of 20%. It is shown that all Al₂O₃-316L coatings exhibit superior corrosion resistance compared to the substrate. As 316L content increases, the corrosion resistance of coatings increases followed by decline. With 316L powder in a mass faction of 20%, the electrochemical impedance of the coating is 2.27 times that of the substrate.

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 improve the surface hardness and wear resistance of Ti-6Al-4V alloy, a cladded coating of TiO₂ and TiN was prepared on the surface of Ti-6Al-4V alloy by laser cladding, and the microhardness, wear resistance, microstructure and element distribution of the coating were explored. Compared to the substrate, the surface hardness and wear resistance of the coating are significantly improved. It is shown that with TiO₂ and TiN powder in a mass ratio of 1∶9, the hardness and specific wear rate of the coating can reach 1936.1HV_0.1 and 2.06×10^-14 mm³/(N·m), respectively, which are 5.4 times and 3.26 times those of the substrate. The main components of the coating include α-Ti, TiN, and TiN_0.6O_0.4, which is the reason for the significant increase in hardness and wear resistance of the TiO2-TiN cladded coating. The research results provide a theoretical and experimental basis for improving the hardness and wear resistance of Ti-6Al-4V alloy by laser cladding technology.

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.

Effects of heat treatment system and Cu content on the microstructure and mechanical properties of two conventionally cast Al-Cu-Mn alloys were investigated. It is found that after treatment at proper temperatures, including 525 ℃×16 h+170 ℃×8 h for Cu2.8 alloy, 525 ℃×16 h+170 ℃×14 h for Cu5.7 alloy, the Cu2.8 alloy and Cu5.7 alloy have their tensile strength up to 209.76 MPa and 349.15 MPa respectively, and yield strength reaching 107.15 MPa and 216.21 MPa correspondingly. The detailed exploration of precipitation behavior of the alloy after aging indicates that Cu content brings an important influence to the precipitation behavior. The precipitation of the T phase leads to depletion of Cu atoms in low-Cu alloy during solid solution process. The θ' phases only adhere near the T phase, and dispersed θ" phases are only precipitated in the high-Cu alloy, which contribute mainly to higher strength of high-Cu alloy.

A kind of silicon monoxide-based anode material coated with layers of lithium titanate and carbon was synthesized by chemical vapor deposition and sol-gel method. The electrochemical measurement shows that with lithium titanate coating at an amount of 3%, the anode material presents good performance, showing that the specific capacity is 1 485.4, 1 443.8, 1 386.4, 1 341 and 1 276.2 mAh/g correspondingly at 0.2C, 0.5C, 1C, 2C and 4C rate respectively, and the specific capacity is 1 138.1 mAh/g after 150 charge-discharge cycles at current density of 750 mA/g. The flexible carbon layer can buffer volume expansion of the internal silicon core and improve the conductivity of the material. The rigid lithium titanate can ensure structural integrity of the material. The synergy of two layers of coatings can effectively improve cycle stability, rate performance and reversible capacity of electrode material.

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 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°.

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 2000 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 3000 g/t and golden cicadas environment-friendly leaching agent for gold at 5000 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.

In order to know the status quo of technologies for deep-sea mineral resources development, the related patents were briefly analyzed. A total of 3236 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.

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 1500 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 confirmedthe feasibility of sodium oleate used in removing titanium by reverse flotation of iron concentrate obtained from magnetic separation of red mud.

In order to balance productivity against safety in the mining of high-level stope with gently-dipping and extra-thick 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 mand 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.

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 1195.90 mAh/g at 1.0 A/g after 500 cycles, presenting excellent durability over a large number of cycles.

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.

According to the relative position between interbedded surrounding rock and the peripheral holes, the relationship between bedding planes and the connecting line of the adjacent blastholes was classified into three kinds. Mechanism for bedding planes bringing impact to crack propagation in rocks between blastholes by blasting under typical work conditions (with bedding planes on the perpendicular bisector of the connecting line of blastholes) was explored by the LS-DYNA numerical simulation; and the effect of bedding planes in a different relative position to the connecting line of blastholes on the blasting effect of surrounding rock was also studied. It is found that the propagation speed of blasting vibration waves in sandstone is slightly higher than that in sandy mudstone. Under blasting loads, the surrounding rock above both softer layer and the beddings suffer severe damage. The superposition of two-blasthole blasting vibration wave peaks intensifies the damage to the surrounding rock. The blasting effect is poor when the bedding plane penetrates the blastholes, but the blasting effect is ideal if the bedding plane is on the perpendicular bisector of the connecting line of blastholes.

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 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 404500 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.

To gain an in-depth understanding of research status of ceramic additive manufacturing, the technical processes of direct ink writing, fused deposition modeling, selective laser sintering, stereolithography and digital light processing, as well as the materials used in those  technologies are reviewed based on domestic and international researches on ceramic additive manufacturing. The advantages and disadvantages of those five technologies are summarized, which can provide references for their application scenarios. Finally, the prospect for the development of ceramic additive manufacturing is also discussed.

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 1500 N. In this case, the maximum horizontal and vertical tensile forces of the hose on the mining vehicle are 941 N and 1258 N, respectively.

The thermal dissipation performance of a battery pack was optimized by thermal simulation, aiming to enhance safety and service life of batteries. A thermal simulation model of the battery pack was established with ANSYS software, and temperature distribution was analyzed for the battery discharged at 1C rate. It is found that the simulation results deviate from actual measurements by less than 0.5 ℃, confirming the high accuracy of the model. Two optimized thermal dissemination schemes were proposed, including I-shaped heatsink and thermally conductive adhesive filling. Study shows that both schemes can effectively improve the thermal dissipation performance, leading to the maximum temperature of cells reduced by 6.0 ℃ and 5.9 ℃, respectively. The scheme of I-shaped heatsink can not only reduce cell temperatures but also significantly reduce temperature differences, resulting in better thermal uniformity.

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%.

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.

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.

A seabed collector vehicle usually carries a large amount of sediments during mining seabed polymetallic nodules. For reducing the environmental impact caused by tail water discharged in the mining, two kinds of high efficiency and low diffusion desliming pretreatment devices, with twine-drum spiral  structure and  a direct discharge device with arresting mesh structure, respectively, have been developed,which integrates a  jet-assisted transport testing equipment, and is also equipped with an online monitoring system. The desliming effect and environmental performance of the developed device was evaluated by performing computational fluid dynamics simulations and laboratory tests. It is found that the direct discharge device with arresting mesh can pretreat tails with desliming rate over 98%, and this pretreatment device can make quick separation of nodules from sediment, and also lead to subsequent quick settlement of the separated sediment, thus effectively controlling the plume caused by collector in the mining. It is concluded that this developed pretreatment device can improve the lifting efficiency in the mining and mitigate the pollution of tails in the deep-sea mining from the source.

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.

According to the characteristics of high-content aluminum and low-content lithium in hydrochloric acid leaching solution of a clay-type lithium ore in Hubei Province, lithium and aluminum were firstly separated by adopting calcination at 390 ℃ for 2.0 h. Then, the calcined residue, without grinding, was leached at 90 ℃ for 1 h with water in a volume ratio of 3∶1. After the leaching process, the leaching rate of lithium reached 93.85%, and no aluminum was detected in leaching solution, indicating a good Li-Al separation result. An analysis of chemical composition of calcined residue and leaching residue show that after water leaching, the main metal elements in the calcined residue, such as lithium, kalium, sodium, calcium and magnesium, all are leached into the lixivium, and the main composition of leaching residue are alumina and iron oxide.

Based on the study on reduction behavior of vanadium during the smelting of vanadium-bearing titanium concentrate in an electric furnace, the comprehensive recovery of vanadium resources was explored through experiments. The vanadium-bearing titanium concentrate from Yunnan Province was taken as raw material to carry out an industrial-scale smelting experiment in an electric furnace with different carbon ratios. Based on the thermodynamic theory, the distribution and influencing factors of vanadium element in slag-iron phase were all analyzed. The results show that with carbon ratio up from 6.5% to 14.0%, the mass fraction of TiO₂ in titanium slag increases from 54.12% to 92.51%, the proportion of vanadium element reduced into molten iron increases from 1.14% to 6.61%, and the proportion of vanadium element left in the titanium slag decreases from 92.95% to 88.17%. It is found that there is a small amount of vanadium in dust, accounting for about 5.5%, which has no significant correlation to carbon ratio. The smelting process of titanium slag is not conducive to vanadium reduction, which is principally attributed to carbon deficiency operation and low-basicity slag system. It is not economically feasible to extract vanadium from molten iron by smelting vanadium-bearing titanium concentrate in an electric furnace, so it is suggested that vanadium should be extracted from the vanadium mud obtained after refining and vanadium removal process of titanium dioxide.

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.

Based on the analysis of patent application trend, major applicants and technological development in  recycling of spent lithium iron phosphate batteries by leaching process, a list of key patents of mainstream technologies is presented. The results show that the number of patent applications for recycling of spent lithium iron phosphate batteries by leaching process has been steadily increasing since 2015, and oxidative acid leaching is the mainstream technology at present, with other technologies keeping in pace. However, some outdated technologies are being phased out.

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.

For estimating the amount of infiltrated water during heavy rainfall after transition from open-pit mining to underground block caving, the Beiyi mining area of Shilu Iron Mine in Hainan Province after transition from open-pit to underground mining was taken for study. The characteristics of “three zones” formed due to overburden subsidence during the block caving of Beiyi mining area were analyzed based on the field investigation and numerical simulation of land subsidence area. The influence of different overburden on the infiltration coefficient of rainfall was also analyzed with a numerical calculation model for unsaturated overburden. Then, based on the practical measurement of rainfall and drainage, statistical analysis and inverse analysis were conducted for the infiltration coefficient of the caving zone and the surface runoff coefficient. The infiltrated water due to heavy rainfall in Beiyi mining area after transition from open pit from underground mining is calculated to be 225 386 m³, which can provide a reference for the design of infiltration and drainage system for the mine after transition from open-pit to underground mining.

To study the distribution of flow and pressure in the slurry pipeline of large-diameter slurry shield, Simcenter  Flomaster was used to simulate the slurry pipe for calculation, and a one-dimensional model was established for the slurry pipe of large-diameter slurry shield. The distribution of flow and pressure in the pipeline under different working conditions by changing the valve opening degree, fluid density and rotating rate of pump were recorded, so as to obtain the optimal flow distribution. The calculation results show that valve opening degree, fluid density and rotating rate of pump all have a certain influence on the distribution of flow and pressure in the slurry pipeline system. By increasing valve opening degree, the flow rate in the pipeline increases and the pressure difference between two ends of the pump is reduced; as the fluid is changed from clear water to slurry, the flow rate in the pipeline increases and the pressure difference between two ends of the pump decreases; as the pump rotates at a lower rate, both the flow rate and the pressure difference are reduced. If the rotating rate of discharging pump is too low, the discharging pipe can be kept operating normally by increasing the rotating rate of the discharging pump or adding another pump in series.

The alloy structural steel for gear shafts was treated by adopting a quenching and partitioning process, and effects of temperature and time of partitioning on the tensile properties, physical phase composition, microstructure and fracture morphology of structural steel were all explored. The results show that when the end temperature of fixed quenching and temperature of partitioning remain unchanged, extension of partitioning time can lead to gradual decrease in the tensile strength of the steel for gear shafts, and an increase followed by decrease in the fracture strain; with partitioning temperature at 225 ℃ and 275 ℃ respectively, the highest fracture strain is obtained at partitioning time of 120 s and 90 s, respectively; extension of partitioning time can lead to an increase followed by decrease in the strength-elongation product of the steel for gear shafts; the highest strength-elongation product can be obtained when the partitioning time is 90 s, and the strength-elongation product of the sample after quenching and partitioning treatment is obviously higher compared to the sample just treated by quenching. There is almost no residual austenite in the directly quenched sample, while the residual austenite in the sample by quenching and partitioning treatment is in a volume fraction of 3.0%-6.4%. It is found that at the same partitioning temperature, extension of partitioning time can result in martensitic tempering transformation, and carbide precipitation and growth in the steel for gear shafts.

Manganese-rich phase with low impurity content was prepared with manganese sulfate crude solution by precipitation. A single-factor experiment was carried out to explore effects of reaction time, reaction temperature, pH value and feeding speed of precipitating agent on precipitation efficiency, and then the content of impurity in the finally prepared manganese-rich phase was also analyzed. After the leaching solution with Mn²⁺ in mass concentration of 38 g/L, and pH of 8.0 was precipitated at 60 ℃ for 4 h, with R as precipitating agent fed at a speed of 0.5 L/h, the conversion rate of Mn²⁺ was 94.3%. The ICP and EDS analyses showed that there were low content of impurity ions (K, Na, Ca, Mg) in the precipitate of manganese-rich phase.

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·%.

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.