Theoretical calculation was made for the flow field in the hydraulic transportation with deep-sea polymetallic nodule collector, and the relationship between particle size of polymetallic nodules and minimum conveying speed was obtained. The distribution of flow pattern in the conveying channel was simulated with the jet velocity of nozzle at 15 m/s, 20 m/s and 25 m/s respectively, and rate of the flow at 30 mm away from the lower surface of the channel was measured. A laboratory test was conducted for nodules pick-up by using a collector with different jet velocities of nozzles, and it is found that the obtained results are consistent with the theoretical calculation and simulation results.

Based on the in-depth investigation of the geological characteristics of the phosphate mines in western Hubei, including Sujiapo Phosphate Mine, Maping Phosphate Mine and Taoyuxi Phosphate Mine, rock burst phenomena were analyzed in terms of influencing factors of occurrence position, buried depth and lithology. The appropriate control measures are proposed for rock burst in those phosphate mines in western Hubei. In-situ stress of underground phosphate rock in western Hubei was tested. Based on the obtained results, the mining sequence was optimized to avoid mining operation in the stress concentration area as much as possible, and pressure relief and support measures were taken in local areas to ensure safe underground mining.

In order to simply and effectively evaluate slope stability, four machine learning models based on chaotic particle swarm optimization (CPSO) were proposed to solve the existing problems of algorithm selection and hyper-parameter optimization in traditional machine learning model, and their prediction performance were comprehensively compared among each other. A database consisting of 221 open-pit slope stability cases was established, in which 80% of the data were used for training and 20% for model testing. Based on the comparison between the prediction results of four models and the verification results of engineering practices, it is found that the support vector machine (SVM) based on CPSO is superior than other three machine learning models in terms of prediction of slope stability, presenting an accuracy up to 88%. Thus, it can provide a reliable prediction for the safety of slope in open-pit mine.

The lifting of polymetallic nodules was simulated by using a CFD-DEM coupling approach, and the influence of different swirling flow on hydraulic lifting of polymetallic nodules in vertical pipelines was explored. The results show that as swirl ratio increases, the intensity of swirl will be enhanced significantly, and both the maximum fluid velocity and the average axial velocity of particle group will increase. It is found that intensity of swirl can bring obvious impact to the distribution of particles with different velocity in the pipe, showing that particles with high velocity are gradually distributed around the pipe wall, while the particles with low velocity in the center of the pipe. Swirling flow can reduce the local concentration of particles, which is beneficial to reducing the risk of pipeline blockage due to higher concentration of particles caused by retention effect.

Based on the analysis of ore dilution in Barun mine, the dilution rate at the junction of ore and rock in Barun open-pit mine was controlled. With the actual production into consideration, some controlling measures are put forward for the mine, including accurately identifying ore-rock boundary by drilling and sampling, separating ore and rock by blasting, accurately identifying the ore-rock boundary in muck-pile by blasting, and optimizing shovel loading operation among others. As a result, less waste rock has been mixed with ore, leading to the ore dilution down to below 2%. It is shown that the rate of extraction can be obviously improved.

The key factors of pile foundation settlement were explored for the slope under vertical load by using grey relational analysis, and it is found that each factor is in the following descending order by its influence: elastic modulus > slope distance > slope gradient > internal friction angle > cohesion > soil density > poisson's ratio of soil > pile length > pile diameter. In order to optimize the parameters of support vector regression (SVR) model, a novel HGWO-SVR model was proposed by integrating the differential evolution-enhanced gray wolf algorithm (HGWO). Compared with GWO-SVR and GS-SVR models, this model presents obvious advantage in prediction, with high accuracy and minor error. A settlement prediction model for pile foundation of slope was constructed based on HGWO-SVR model, and the prediction results were compared with those values calculated with existing settlement formulas. The results show that the maximum percentage error between the prediction value of HGWO-SVR model and the calculated value is 6.55%, thus verifying that this model is feasible in settlement prediction for pile foundation of slope.

The ground surface displacement caused by open-pit mining of a large iron mine in Hainan was analyzed by using fuzzy measurement theory. Base on the comparison with the calculated results by using the theory of random media, it has verified that the fuzzy measurement theory is superior and practicable in the analysis of influence of open-pit mining on the surrounding environment.

A numerical model was established by using LS-DYNA software and then used to simulate the influence of pre-split fracture with width of 3 cm and 5 cm, respectively, on blasting effect. It is found that wider pre-split fracture can bring a better effect of blasting vibration attenuation, with the maximum amplitude decay rate of 46%. Based on pre-split blasting tests with different borehole sizes, the on-site vibration monitoring results have verified the correctness of the rule. It is concluded that the parameters of pre-split blasting should be selected based on the actual working conditions in consideration of protection of surrounding buildings.

A Gamma-ray concentration meter based on Kalman filtering was designed, and the relationship between ray intensity attenuation and slurry concentration was established by analyzing the measurement principle of ray concentration meter. To suppress the disturbance of the results, an optimal estimation of ray intensity was actualized by using Kalman filtering. The corresponding concentration is segmentally simulated and calculated by using the least square method. The results show that the concentration meter can provide timely and accurate measurement, with a maximum error of 0.328 percentage points and a root mean square error of 0.194 percentage points, presenting effective improvement in accuracy.

Beneficiation tests were conducted to process the low-grade cobalt-nickel ore from Hebei Province by adopting an asynchronous flotation flowsheet consisting sequentially of staged grinding, flotation of sulfide minerals and flotation of sulfurized oxide minerals. In the study, combined depressants were used for better depressing of slime, while regrinding process was introduced to intensify the sulfurization effect. Finally, a cobalt-nickel sulfide concentrate with Co grade of 2.00% and Ni grade of 3.90% and a cobalt-nickel oxide concentrate with Co grade of 1.47% and Ni grade of 2.73% were obtained. The total Co recovery and total Ni recovery reached 77.61% and 79.20%, respectively. In this way, the preliminary enrichment and recovery of Co and Ni resources can be realized, laying a foundation for their further purification.

In response to the problems of high molybdenum loss and difficulty in molybdenum/talc separation existing in the desliming process of a high talc-type molybdenite ore from Henan, ZN-J1, a molybdenum depressant, was introduced in the desliming section to minimize efficiently the molybdenum loss. The feed ore with Mo grade of 0.116%, molybdenum sulfide percentage of 83.53% and talc content of 14.0% was processed by adopting a flowsheet, consisting of desliming, pre-flotation of molybdenum, regrinding, and molybdenum/talc separation, with a combination of sodium silicate and ZN-P1 as depressant. A closed-circuit test with the whole process produced a molybdenum concentrate with Mo grade of 47.68% and Mo recovery of 75.41%, respectively.

To utilize efficiently valuable metal resources containing lithium and beryllium, flotation experiments were conducted based on the study of ore properties. A lithium-beryllium bulk flotation process was used and the influences of dosages of regulator, activator and collector, and the stirring time of regulator on the flotation performance of lithium polymetallic ore were investigated. Based on the determined optimal dosages of calcium chloride and collectors of GYLZ and GYM3, a closed-circuit test produced a lithium concentrate with Li₂O grade and recovery of 6.10% and 94.01% respective, and BeO grade and recovery of 0.12% and 88.53%, respectively, achieving efficient recovery and utilization of lithium and beryllium resources in lithium polymetallic ores.

A vertical stirring mill was introduced for regrinding the graphite concentrate from the rougher in a graphite mine of Heilongjiang Province. Using ceramic ball as the grinding medium, the influences of processing parameters, including rotation speed of mill, diameter of medium ball and grinding time, on the grinding and flotation performances of graphite ore were investigated. The graphite ore was beneficiated adopting an open-circuit flotation process after it was milled with the optimized grinding parameters including alternating (slow-fast-slow) rotation speed, medium ball diameter of 8-10 mm and grinding time of 5 min. The as-obtained graphite concentrate, with the 24.51% in a size fraction of -0.045 mm, has a fixed carbon content of 95.83% and large-flake graphite content of 14.27%.

The occurrence state of iron minerals in a kind of kaolin ore in Guangdong is relatively complex. A portion of iron minerals is irremovable as they disseminate in the lattice of kaolinite, illite and other minerals in an isomorphic manner. For this reason, the calcined kaolin concentrate possesses a lower whiteness than the natural whiteness. In order to efficiently exploit and utilize the kaolin ore, a process consisting of slurry tamping, spiral classifier classification and hydrocyclone classification was adopted, resulting in a kaolin concentrate grading 30.02% Al₂O₃ at 61.70% recovery with the content of impurity Fe₂O₃ at 1.15%, which can reach grade III standard of kaolin for ceramic industry. The classification downflow was then subjected to a process consisting of grinding, magnetic separation and hydrocyclone classification, resulting in a quartz sand concentrate and a sericite concentrate. The quartz sand concentrate, containing 97.11% SiO₂ and 0.058% Fe₂O₃, can satisfy the standard for low quality quartz for glass industry, and the sericite concentrate, containing 7.07% K₂O, 31.22% Al₂O₃ and 48.32% SiO₂, with natural whiteness at 65.53%, can be used in the coating industry. The magnetic separation results in the tailings with a yield of 8.41% and SiO₂ content of 76.33%, which can be used as auxiliary materials for building sand. Through this process, different minerals can be effectively separated to achieve the purpose of comprehensive utilization of kaolin ore.

By means of X-ray diffraction, optical microscopy, scanning electronic microscopy, mineral liberation analysis and chemical analysis, the paigetite ore from Wengquangou mine in Liaoning Province was studied in terms of its chemical component, mineral composition and content, and the occurrence state of main minerals. After main dissemination characteristics of target minerals and key factors in mineralogy influencing beneficiation performance were ascertained, some corresponding separation techniques were proposed.

Based on the process mineralogy study, an experiment was performed on flotation of a phosphogypsum from Hubei Province for its purification. The experiment was run in stronger acid solution with T-609 as the collector, by adopting a process consisting of one roughing, one scavenging, and two cleaning, resulting in the final cleaning concentrate with the content of calcium sulfate dihydrate over 99%, with a whiteness of 75% at 200 ℃. It is shown that this processing flow is characterized by simplicity, high separation rate of phosphogypsum, less addition of agent. The obtained product, with low content of impurities, is up to the special grade in the national standard for gypsum, and can be used for preparation of high-end building materials and gypsum whiskers.

To examine the industrial feasibility of pre-discarding by using screening classification combined with gravity separation in processing of a scheelite ore from Hunan Province, industrial distributary and flotation trial tests were carried out. The results show that a process consisting of screening and spiral chute discarding under optimized conditions can discard tailings grading 0.034% WO₃ with a yield of 25.50% in mass, leading to tungsten loss of only 2.99%. With this pre-discarding before flotation process, both the grade and recovery of the final flotation concentrate are improved, compared to the concentrate obtained from direct flotation of overflow product.

As for a zinc concentrate collected from mineral processing of a lead-zinc ore, an experimental study was carried out to reduce the carbon content therein. With soluble starch as the carbon depressant, a concentrate with Zn grade of 48.71%, carbon content of 0.86% and Zn recovery of 90.28% was obtained from a closed-circuit test. Compared with the on-site indicators, both the Zn grade and recovery of concentrate are increased by using this new process, while the carbon content therein is reduced to less than 1%, showing a remarkable carbon-reduction effect.

High pressure grinding roll (HPGR) was used to comminute a copper smelting slag. An open-circuit test, edge-product cycling test and closed-circuit ball mill test were carried out using HPGR. The particle size of various products were measured, and the grinding results after HPGR were compared with those obtained after jaw crushing. The results show that after copper smelting slag is processed using HPGR and ball mill, the fine particle fraction of the products increases obviously, and the grindability increases by about 36 percentage point. It can be concluded that HPGR approach favors upgrading of grinding efficiency and beneficiation index in processing copper smelting slag.

In order to recover and utilize high value-added iron phosphate waste, an experimental study was carried out by adopting a process consisting of hydrochloric acid leaching, replacement of iron powder for copper removal, and hydrolyzation and chemical precipitation for removal of titanium and aluminum therein. The results show that after 1 h leaching at 60 ℃ with hydrochloric acid concentration of 25%, liquid-solid ratio of 6 mL/g, the leaching rate of iron can be up to 98.7%. And then after 35 min reaction at 60 ℃ with the initial pH of the solution controlled at 0.6, the addition of iron powder at an amount of 0.55 times of the molar number of iron in the leaching solution, the removal rate of copper and titanium can reach 96.2% and 83.6% respectively. By the following process of hydrolyzation and chemical precipitation with sodium fluoride 8 times of the molar number of aluminum, the removal rate of titanium and aluminum can reach 97.6% and 99.3% after 30 min reaction at 40 ℃ with pH of 1.9. It is shown that the content of impurities in the leaching solution meets the requirements for the subsequent synthesis of iron phosphate for batteries.

Experiments were carried out to compare dephosphorization performance of CaCO₃, Na₂CO₃ and CaF₂ in direct reduction roasting process of high-phosphorus hematite. It is found that Na₂CO₃ presents the best dephosphorization performance, followed by CaCO₃. The molecular dynamics simulation was conducted to calculate the distribution of bridging oxygen and the mean square displacement (MSD) of oxygen atoms during the roasting process of the system with three different additives respectively, and the dephosphorization mechanism of CaCO₃, Na₂CO₃, CaF₂ during the direct reduction process of high-phosphorus hematite was explored. The results show that the mechanism of dephosphorization by additives is to inhibit reduction of apatite by increasing the content of free oxygen or the MSD of oxygen atoms in the system and reducing the oxygen atoms shared by Si and P in the system. It is found that the dephosphorization performance of additives is positively correlated with the MSD of oxygen atoms in the system.

Alkali leaching of indium from zinc indium ferrite (ZnFe_2-xIn_xO₄) was strengthened by applying a combination of ultrasound and microwave. The results show that there are not a great amount of solid solution of indium in the octahedral lattice of ZnFe_2-xIn_xO₄, and the maximum solid solution approaches 4.0% in a mass fraction (x=0.088). The leaching rate of indium can be enhanced by the external fields in the following descending order: a combined application of ultrasound and microwave, single application of microwave, application of ultrasound followed by microwave or microwave followed by ultrasound, and single application of ultrasound. It is shown that the leaching rate of indium can be up to 56.6% with a combined application of ultrasound and microwave, but only reach 30.2% by singly applying ultrasound. During the alkaline leaching under the external fields, In³⁺ can be released from the lattice, while the octahedral lattice of zinc ferrite will not collapse. With a combined application of ultrasound and microwave, more In³⁺ can be released, leading to lattice constant becoming much smaller. The XRD spectrum shows obvious reduced intensity and rightward movement of diffraction peaks.

In order to avoid formation of material ring in a rotary kiln caused by kiln phosphoric acid process, a technique of high-temperature consolidation of pellets was proposed, and the effects of types of binder, temperature and time of consolidation on the strength and reducibility of phosphate ore pellets were investigated. The results show that consolidation at a temperature over 800 ℃ with bentonite as binder can lead to the pellets with compressive strength and drop numbers obviously higher than those with sodium humate as the binder. With an addition of carbon at 1.4 times of the theoretical amount, CaO and SiO₂ at a molar ratio of 0.35, an addition of bentonite at an amount of 1.5% of the total material weight, consolidation at 1 000 ℃ for 30 min results in the produced pellets with compressive strength of 345.36 N and drop numbers of 33.50.

A kind of contaminated paddy soil was taken for pot experiment by adding FeSO₄ to investigate the impact of FeSO₄ on the formation of iron plaques on the root surface and the migration of the Cd from Cd-contaminated paddy soil. Results show that with the addition of FeSO₄ increased from 0 to 320 mg/kg, the pH value of the paddy soil tends to decline, maximally by 0.70. The TCLP-Cd content in the potting soil rises to a certain extent compared to the control group. The addition of FeSO₄ significantly reduces the Cd content in leaves, husks, and brown rice, as well as effectively increases the amount of root iron plaque, thus the absorption of Cd in the soil by rice is moderately controlled. However, the addition of external iron resource can bring impact to the pH of soil and bioavailability of Cd, so it is recommended that in practical operation, FeSO₄ should be added with some alkaline restorative materials such as lime to contaminated paddy fields for enhancing the control.

High purity sodium aluminate was prepared with sodium aluminate solution by adopting a process consisting of evaporation, cooling crystallization, and dewatering for purification. The effects of additives on caustic ratio and crystallization products, as well as the function and behavior of sodium aluminate solution during evaporation and crystallization were studied. The results show that with NaOH as an additive, the caustic ratio of the solution system can be increased, and the product from evaporation and crystallization can be converted to NaAlO₂. By using NaAlO₂ as seed crystal and adjusting the caustic ratio of system to 1.36 with NaOH, the product of NaAlO₂ with purity of 88.1% can be obtained after evaporation at 100 ℃ for 2 h with stirring rate of 300 r/min. Then, after 1 h dewatering at 200 ℃ and 1 h purification with alcohol at 100 ℃, a kind of solid NaAlO₂ can be obtained with purity of 93.8% and crystal particles of 5-25 μm.

With aluminum hydroxide powder as raw material, aluminum hydroxide was roasted into α-Al₂O₃, and the phase transformation and microstructure change during the process were investigated. Then, the kinetics of the calcination process was calculated by simulation with multiple scanning method. It is found that the optimum conditions for aluminum hydroxide calcinated into α-Al₂O₃ are as follows: calcination temperature of 1200 ℃, time of 2 h, heating rate of 5 ℃/min. Three endothermic peaks can be observed during the calcination process of aluminum hydroxide, corresponding to three weightlessness stages. In the first stage of reaction, the function of mechanism is G (α)=[(1-α)^-1/3-1]², the average activation energy is 91.16 kJ/mol and the pre-exponential factor is between 17.00×10⁹ and 44.03×10⁹ min^-1. In the second stage of reaction, the function of mechanism is G (α)=α², the average activation energy is 106.2 kJ/mol and the pre-exponential factor is between 7.70×10⁹ min^-1 and 18.60×10⁹ min^-1. In the third stage of reaction, the function of mechanism is G (α)=α^1/4, the average activation energy is 235.42 kJ/mol, and the pre-exponential factor is between 39.94×10⁹ and 50.79×10⁹ min^-1.

Based on the studies of catalytic pyrolysis for high-sulfur waste residue (HSWR), it is found that after 90 min pyrolysis at a temperature of 600 ℃, with Fe₂O₃ as a sulfur fixation agent in a mass ratio of 1.5∶1 with HSWR, the total desulfurization rate can be around 85%. The volatile sulfur-containing complex organic matter in HSWR could be transformed into stable inorganic matter, among which the amorphous sulfur could be transformed into crystalline sulfur with purity over 95%. In the residue left after pyrolysis process for desulfurization, the main components include inorganic salts such as sodium sulfate and carbon black. The exhaust gas is mainly composed of simple molecular organics such as CH₄ and C₂H₄, and a small amount of inorganic compounds such as CO, SO₂, CO₂ and HCl. The pyrolysis process for desulfurization consists of four stages: firstly, the amorphous elemental sulfur is vaporized and then crystallized to form crystal sulfur; secondly, as for the elemental sulfur with attachment of organic matter and in a relatively more stable structure, its bond with the hydroxyl or carboxyl of organic phase is broken, leading to sulfur emitted into the atmosphere; at the third stage, the sulfur-containing organic phase is deactivated at the methylene and submethyl sites to form HCl, H₂S and carbon black, which are then adsorbed by sulfur-fixation agent and converted into sulfate; at the fourth stage, the carbon-carbon bond between nitrogen heterocyclic hydrocarbons becomes unstable after grouping, and is broken into small organic molecules such as CH₄ and C₂H₄, as well as carbon black and a trace of H₂. Meanwhile, C—N/C—NH_x bonds are broken into NO_x/NH₃, and C—S/C—SO₃H bonds are broken into H₂S and SO₂, which are then adsorbed by sulfur fixation agents and converted into sulfate.

Methylene blue was degraded by adopting a heterogeneous Fenton system composed of manganese residue and H₂O₂, and the effects of initial pH value, H₂O₂ concentration, dosage of manganese residue and reaction temperature on the degradation performance were studied. The reusability of manganese residue was investigated, and the removal mechanism of methylene blue in the manganese residue/H₂O₂ system was also discussed. The results show that the removal rate of methylene blue can exceed 98.1% after 120 min reaction at temperature of 25 ℃, with methylene blue concentration of 20 mg/L, H₂O₂ concentration of 10 mmol/L, manganese residue dosage of 2 g/L, and initial pH value of 2.5. After the manganese residue is recycled for 5 times, the removal rate of methylene blue can be still up to 95.5% by 300 min reaction. In the manganese residue/H₂O₂ heterogeneous Fenton system, ·OH plays a leading role in the degradation of methylene blue.

MIL-53(Fe), a metal-organic framework (MOF) material, prepared by using solvothermal synthesis was adopted to adsorb Sb(Ⅲ) in soil. MIL-53(Fe) was used as the adsorbent to adsorb the Sb(Ⅲ) in aqueous solution, and the effects of solution temperature, pH value, adsorbent dosage, initial concentration of Sb(Ⅲ), and humic acid content on adsorption performance were explored. Then, the isotherms and kinetics of adsorption were also analyzed. After 15 d remediation with the adsorbent at an amount of 3%, the TCLP testing shows that the concentration of leachable Sb(Ⅲ) decreases by 94.2%. However, the pH value and humic acid content of the solution have little effect on the adsorption performance. For 25 mL solution with concentration of Sb(Ⅲ) at 10 μg/mL, addition of 20 mg MIL-53(Fe) can bring good adsorption effect. The initial concentration of Sb(Ⅲ) has a significant impact on the adsorption of Sb(Ⅲ) by MIL-53(Fe). At equilibrium, the maximum adsorption capacity of the adsorbent is 102.9 mg/g. The adsorption isotherm of this process fits with the Freundlich model, and its adsorption kinetics can be described using pseudo-second order model.

With micron silicon powder as matrix, phosphorus-doped silicon-carbon composite material (Si-P@C) was synthesized by solid-state thermal diffusion and high-temperature pyrolysis, and then used as anode material of lithium-ion batteries. The results show that Si-P@C anode material demonstrates an initial discharge specific capacity up to 2164 mAh/g at a current density of 0.2 A/g. Compared with pure silicon, Si-P@C anode material presents greatly improved cycling performance. After 50 cycles at a current density of 0.5 A/g, it demonstrates a high reversible specific capacity of 1 176 mAh/g, with the capacity retention ratio of 73.5%. It is concluded that phosphorus-doping and carbon coating can effectively improve the electron transfer ability and reaction kinetics of silicon anode.

Aluminum sulfate, sodium hydroxide, and high-aluminum pickling sludge were used as raw materials to prepare pseudo-boehmite by adopting a dual aluminum source method. The effects of pH value, reaction temperature, and urea addition on the formation and structure of pseudo-boehmite, as well as the effects of synthesis conditions on the phase and structural properties of pseudo-boehmite were investigated. The results show that as the reaction temperature increases, the specific surface area and pore volume of pseudo-boehmite increase, and the crystallinity also increases. With pH value between 6.5 and 9.5, a clear pseudo-boehmite phase can be obtained; with pH value up to 10.5, a trihydrate alumina phase will be formed. The addition of urea can significantly increase the specific surface area and pore size of pseudo-boehmite.

To solve the problem of structural instability of cathode material (LiNi_0.8Co_0.1Mn_0.1O₂)(NCM)) during cycling, a strategy of co-doping of Rb⁺ and Cl^- was proposed for NCM materials. The synergistic effect of co-doping of Rb⁺ and Cl^- in the NCM lattice can increase the diffusion rate of Li⁺ and relieve the internal strain, thus hindering the mixing of Li⁺/Ni²⁺ during high cut-off voltage cycling. Electrochemical test results show that Li_0.99Rb_0.01(Ni_0.8Co_0.1Mn_0.1) O_1.99Cl_0.01 (RbCl-NCM) has a discharge capacity up to 176.9 mAh/g at a current density of 10C. The initial discharge capacity at 1C is 203.5 mAh/g. After 200 cycles, its capacity retention ratio is as high as 87.8%, showing an excellent cycling performance, while the capacity retention ratio of NCM material is only 57.3%.

To solve the problem of unstable slurry, low density of sintered body, and high carbon residue, the effect of different resin monomer on additive manufacturing of 5052 aluminum alloy with light curing strategy was explored. It is found that different type of monomer can bring great impact to the process of additive manufacturing with light curing strategy and the properties of the following sintered product. When the aluminum slurry prepared with TMPTA or PEG400DA has viscosity higher than 30 Pa·s and settling time is more than 120 h, the formed aluminum alloy substrate has a complete structure with more pores on the surface. When the aluminum slurry prepared with PEG200DA or HDDA has viscosity less than 30 Pa·s and the settling time is less than 16 h, the formed aluminum alloy substrate has no pores on the surface, but is prone to have incomplete structure. When the aluminum slurry prepared with PS-PCL has viscosity less than 30 Pa·s, and is stable and not prone to settling, the formed substrate has a complete structure with no pores on the surface. When the aluminum slurry with solid content around 55% was prepared with PS-PCL, after additive manufacturing process and sintering, the obtained sintered product has the relative density higher than 95%, relativly lower carbon residue (0.259 17%) and relatively higher hardness (29.94HV), with obvious necking growth on the fracture.

The comprehensive recycling ways for tailings after vanadium extraction, including recovery of valuable components, synthesis of new functional materials and preparation of multi-purpose building materials, were explained, which can provide a reference for application of technologies in comprehensive recycling of tailings after vanadium extraction.

Aiming at low intelligence in nickel plate surface defect detection, a detection method based on improved YOLOv5 was proposed. Firstly, the image-enhanced dataset of nickel plate was re-clustered by K-means++ to improve the adaptability of the anchor frame to the dataset. Secondly, the convolutional block attention module (CBAM) was added into the Backbone network to strengthen the feature recognition of interest areas and unclear targets by integration of spatial and channel information. Finally, an efficient IoU (EIoU) loss was introduced to replace the original CIoU loss during bounding box regression to effectively improve the convergence speed of regression, thereby increasing the model detection speed. The experimental results show that with the self-established dataset of nickel plate defect, the improved model, compared to Faster R-CNN, SSD, YOLOv3 and YOLOv5, has higher detection accuracy up to 81.4% on average, with detection speed reaching 61 frames per second. It is concluded that this model can not only improve detection accuracy, but also satisfy the requirements for detection speed.

Effects of electrochemical deposition time on the phase, morphology, bioactivity of hydroxyapatite (HA) coating and the bonding strength with the substrate were investigated adopting alkali-treatment of titanium alloy followed by electrochemical deposition. Results show that the electrochemically deposited coatings prepared on the surface of alkali-treated titanium alloy are composed of flake HA phases, and the electrochemical deposition time has no effect on the phase composition of the coatings, but will bring impact to the coating thickness. After 60 min deposition, the obtained HA coatings is very compacted and has the bonding strength with the substrate up to 17.85 MPa. It is shown that the HA coatings obtained after each deposition time have good bioactivity. In the simulated body fluids (SBF), CO₃^2- substitutes PO₄^3- in the HA into apatite to form steamed bun-shaped carbonated hydroxyapatite（CHA），with the diameter of 7-8 μm. After being immersed in SBF for 3 days，the CHA can be spread all over the surface of HA.

Mg-1%Al alloy plates were rolled at different strain rates, and the effects of rolling strain rate on microstructure, mechanical properties and damping properties of Mg-1%Al alloy were investigated. As rolling strain rate increases, the average grain size and recrystallization volume fraction of Mg-1%Al alloy increase, while the tensile strength, yield strength and texture strength decrease. As the rolling strain rate increases, the elongation decreases after an initial increase, reaching the highest (25.33%) at a strain rate of 20 s^-1, and the damping performance at room temperature is also improved. The damping value is 0.061 with the strain amplitude of 0.1% at a strain rate of 30 s^-1, which is 1.5 times of that at a strain rate of 15 s^-1. At a certain strain rate, the damping performance decreases as strain frequency increases.

With Ba (OH)₂·8H₂O and Ti (OC₄H₉)₄ as raw materials, and isopropanol (IPA) as solvent, tetragonal-rich BaTiO₃(BTO) nanopowder was synthesized by adopting solvothermal process. Effects of Ba/Ti ratio, pH value, solvothermal temperature and time on synthesis of tetragonal-rich BTO powders were investigated, and the mechanism of IPA in the solvothermal process for synthesis of BTO powders was also characterized by X-ray diffraction and scanning electron microscopy. It is found that in the solvothermal process, IPA will preferentially provide certain—OH to promote the hydrolysis of Ti (OC₄H₉)₄, generating TiO₆ octahedra to interconnect with Ba²⁺, which is gradually transformed into the tetragonal phase BaTiO₃ with regular morphology after phase transition, dissolution of small particles, and recrystallization in a low alkalinity environment. Experimental results show that under the following conditions including Ba/Ti ratio of 1.6, pH of 10 for the system, a solvothermal process at 220 ℃ for 24 h, calcination at 950 ℃ for 2 h, the synthesized tetragonal-rich BTO nanopowder is well dispersed with regular morphology, square or nearly square shape, with c/a value of 1.009 4 and particle size of 124 nm on average.

To study the effects of welding parameters on the tolerance of friction stir welding (FSW) of dissimilar aluminum alloys, the mechanical properties and structure of joint of dissimilar aluminum alloys (A356 and AA6061) by FSW under different welding parameters were studied by means of micro-hardness testing, tensile mechanical properties testing, scanning electron microscopy among other analytical testing means. The results show that as for the workpieces with the gap from 0 mm to 1 mm, the welded joint has tensile strength decreased significantly and presents visible welding defects. With tool pin of the same specification, the material flow can be promoted by decreasing the welding speed from 120 mm/min to 80 mm/min, thus the tolerance of workpiece gap will be greatly improved. The tool pin with diameter increased from 4 mm to 6 mm can lead to higher tolerance for welding, but also the material with a higher fusion degree and without delamination.

The effects of brightening agent, such as polysodium dithiodipropanesulfonate (SPS) and sodium 3-mercapto-1-propanesulfonate (MPS), on electrodeposition of Cu from electrolyte with Cu²⁺, H₂SO₄, Cl^- concentration of 85 g/L, 100 g/L and 20 mg/L respectively were studied by adopting linear scanning voltammetry and cyclic voltammetric stripping (CVS), and the effects of SPS and MPS on the tensile strength, elongation, glossiness and roughness of electrolytic copper foil for Li-ion batteries were discussed. The results show that SPS and MPS can promote copper electrodeposition, and also SPS is better than MPS in promotion. However, the compounding with collagen and hydroxyethylcellulose will result in less promotion of copper electrodeposition. In addition, SPS is conducive to improving the tensile strength of copper foil, and MPS is conducive to improving the elongation of copper foil. With concentration of SPS and MPS at 1 mg/L and 1.5 mg/L respectively, the prepared copper foil has flat and dense surface, with better glossiness and roughness.