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 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.

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.

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.

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.

In order to address problems of high cost, high noise and low efficiency of traditional smooth blasting technology, a new charging structure without a detonating cord was proposed, and the parameters were determined according to the requirements of smooth blasting. Tests on smooth blasting without a detonating cord were carried out for blastholes with non-coupling coefficients of 3.8, 3.9 and 4.0, respectively. Based on the analysis of the half-hole rate after smooth blasting, the smooth blasting effects of blastholes corresponding to three non-coupling coefficients were analyzed based on comparison. The results show that each blasthole for smooth blasting can be successfully initiated by using a charging structure without a detonating cord, and the half-hole rates of blastholes are 78.40%, 89.60% and 57.60% respectively corresponding to those three non-coupling coefficients. It is concluded that an optimal non-coupling coefficient of this new smooth blasting technology in the test is 3.9.

An acoustic emission (AE) test of granite under uniaxial step loading was carried out, and the evolution characteristics of AE frequency, event incidence and fractal dimension of the sample at each load-holding stage before occurrence of instability and fracture were analyzed. The results show that the high-frequency signal first decreases and then increases with the increase of stress in the process of step loading; and macro-instability occurs in the sample at the last stage of step loading, at which the internal micro-cracks in the sample undergo from stable propagation to unstable propagation. The incidence of acoustic emission events decreases gradually as time is prolonged. At the last stage of step loading, the incidence of acoustic emission events decreases first and then increases, unstable fracture in the rock increases and micro-cracks gradually merge and coalesce to form macro-cracks, resulting in overall instability and fracture of the sample; with the increase of stress, the fractal dimension of acoustic emission decreases after an initial increase, and the rock fracture develops gradually in an order way from a disorder way.

Based on the triboelectric charging characteristics of the main minerals of quartz, molybdenite and chalcopyrite in a copper-molybdenum ore, the enrichment effect and mechanism of triboelectrostatic separation of chalcopyrite from the mixture under different conditions were investigated. The triboelectric charging results show that after the interaction with the rotary charger under applied electric voltage, chalcopyrite, molybdenite and quartz are remarkably different in charge-mass ratio. In mineral processing tests, a rotary triboelectrostatic separator (RTS) was adopted to treat an artificial ore with chalcopyrite, molybdenite and quartz in a mass ratio of 1∶1∶8. The results show that with the applied voltage of the rotary charger at -14 kV, the charger rotation speed at 5 000 r/min and the co-flow air velocity at 2 m/s, a copper concentrate can be obtained with Cu grade up from 3.3% to 5.9% at Cu recovery of 90%, and with Cu grade up to 9.3% at a recovery of 50%.

Aiming at uncertainty of beneficiation product zone in dry magnetic separation process, an image segmentation method based on an improved U-Net model was proposed by employing machine vision. In this improved model, convolutional block attention module (CBAM) is utilized to enhance the recognition and attention of the network for target areas, which is beneficial to the segmentation of target objects under complex backgrounds; depth-wise separable convolution is adopted to reduce computational complexity while maintaining accuracy, providing strong support for obtaining high-resolution images of beneficiation product zone. Thus, this model can be applied in magnetic separation and also improve network performance. It is found that this improved model can bring segmentation accuracy up to 92.28%, and also is superior to classic U-Net, DeepLabV3+ and PSPNet models in terms of contour extraction completeness and denoising capabilities.

A kind of polymetallic lead-zinc sulfide ore in Guangxi was taken for experimental research. In view of its characteristics of high zinc and low lead, as well as difficulty in the separation between zinc and lead, a new type of efficient inhibitor JFR-1 was adopted in the experiment. It is shown that the lead-zinc sulfide ore was subjected to a lead-zinc bulk flotation, consisting of one roughing, two cleaning and two scavenging, followed by a separation of lead and zinc, consisting of one roughing, two cleaning and two scavenging, finally resulting in a lead concentrate grading 21.00% pb at 72.82% recovery, a zinc sulfide ore grading 6.96% Zn at 94.21% recovery, and a tailings grading 0.04% Pb and 0.13% Zn with a lead recovery of 10.85% and a zinc recovery of 4.79%. Thus, the enrichment and separation of lead and zinc can be actualized.

Acid mine drainage (AMD) and a pulp regulator, TY-308, were used combinedly for activation in flotation of highly alkali-depressed pyrite, in which AMD was used to neutralize the pulp alkalinity, and TY-308 used to reduce the negative effect of AMD on flotation. A closed-circuit test on flotation with the process consisting of one-stage roughing, one-stage cleaning and one-stage scavenging yielded a pyrite concentrate grading 48.73% S at 97.93% recovery. Compared with the practice using sulfuric acid as the activator, the sulfur recovery can be increased by 1.34 percentage points. Furthermore, not only the cost for AMD treatment will be significantly reduced, but the safety risk associated with the use of concentrated sulfuric acid can be avoided.

The effects of sulfuric acid concentration, calcite particle size, sodium dodecyl sulfate (SDS) dosage and flow rate of dynamic fluid on the apparent density of calcite particles during acid reaction were studied. The results show that when the sulfuric acid concentration is 1%, calcite can sustain at the low apparent density state, and the smaller the calcite sizes, the lower the apparent densities. SDS with a concentration of 300 mg/L can enhance the hydrophobicity of calcite, increase effectively the adsorption density and residence time of CO₂ bubbles on calcite, and prolong the duration of low apparent density of calcite. Dynamic fluids may accelerate desorption of gas bubbles from calcite, which is detrimental to the reduction of apparent density of calcite during acid reaction process, but the SDS treatment can significantly reduce this detrimental effect. Settling tests show that acid reaction can prolong the settling time of calcite particles, creating favorable conditions for the separation of calcite and non-carbonate minerals by gravity concentration.

Based on the mineralogy of the high-sulfur sedimentary bauxite ore from Pingguo area of Guangxi, including mineral composition, structural property and mineral dissemination characteristics, three kinds of technical schemes were proposed according to the ore properties, including flotation, reduction roasting plus magnetic separation, and calcination, and then adopted respectively in experiments of desulfurization. The mineralogical study shows that this bauxite ore contains 65.04% Al₂O₃ with S grade of 5.08%, and the dominant minerals therein are diaspore and pyrite. It is found that the pyrite can be effectively removed by those three processing techniques, and the flotation process can yield an bauxite concentrate with Al₂O₃ grade of 75.90% and the S grade reduced to 0.49%, which is qualified as the feed material for the succeeding alumina extraction. In this case, it is recommended that the flotation be selected as a pre-desulfurization solution for high-sulfur sedimentary bauxite ore.

For a cobalt leaching residue grading 1.31% Cu and 0.20% Co, a flowsheet consisting of grinding and a flotation process of one stage of roughing, one stage of scavenging and two stages of cleaning was proposed based on the occurrence of copper and cobalt therein. A closed-circuit test employing this processing technique can result in a bulk copper-cobalt concentrate grading 16.16% Cu and 2.06% Co with recoveries of 80.56% Cu and 68.29% Co, with the yield of 6.63%. It is concluded that with this approach, copper and cobalt resources in the cobalt leaching residue can be enriched and recovered efficiently.

Collophanite ore was taken in a test to explore the influence of fine particle entrainment content in return sand to grinding on grinding efficiency. It is found that the lower the fine particle entrainment content in return sand, the higher yield of the newly generated particles in the size range of -0.074 mm. Nevertheless, the increase in the yield of particles within the range of -0.025 mm has little to do with the entrainment content in return sand.

Aiming at problems including low content of magnetic iron, fine dissemination size and high content of ferrous silicate in processing of the amphibole-type primary ore in Yuanjiacun Iron Mine, an experimental study was carried out by adopting a pre-concentration process consisting of fine crushing plus dry magnetic pulley separation and a roll grinding plus wet magnetic separation. The pre-enriched concentrate was then processed with a flowsheet including a three-stage grinding, a three-stage low-intensity magnetic separation and a reverse flotation, resulting in an iron concentrate grading 65.66% TFe at 49.31% recovery, with the yield of 21.45%. It is shown that iron resource can be utilized efficiently.

Mo (VI) and Cu (II) in aqueous solution were extracted by using an aqueous two-phase system consisting of isodecanol polyoxyethylene ether (E-1006) and ammonium sulfate ((NH₄)₂SO₄) for the first time, and a phase diagram of the system was also obtained. Effects of initial pH of aqueous phase, temperature of system, and concentrations of E-1006 and (NH₄)₂SO₄ on Mo-Cu separation effect were also investigated. The results show that with pH of 2.0, temperature of 313.15 K, and both E-1006 and (NH₄)₂SO₄ at concentration of 150 g/L, the extraction efficiency of Mo (VI) is 96.08% and the separation factor for Mo (VI) and Cu (II) is 5 131.45.

Illite, a kind of clay mineral, was taken as an adsorbent in an experiment for low-concentration rare earth ions in rare earth leaching solution to explore effects of initial concentration of Y³⁺, adsorption temperature, pH value of solution, ion concentration, and adsorption time on the adsorption behavior of illite. Then, based on the constructed isotherm model for adsorption of yttrium ions by illite and its reaction kinetic model, the mechanism for the adsorption of yttrium ion by illite was analyzed. Results show that illite has an excellent adsorption performance for Y³⁺. With an increased initial concentration, higher temperature, prolonged time, and higher pH value of solution, the adsorption capacity of Y³⁺ for illite increases. It is found that the existence of Na⁺, Mg²⁺ and Al³⁺ can inhibit the adsorption of Y³⁺ by illite in the following descending order of importance: Al³⁺>Mg²⁺>Na⁺. The adsorption reaction follows Langnuir isotherm model and pseudo-second-order reaction kinetic model. Ion exchange reaction takes place during the adsorption process, thus this adsorption process belongs to chemical adsorption, with adsorption rate controlled by chemical reaction.

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.

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

Based on the investigation of occurrence state, fluoride associated with barite was leached with HCl-AlCl₃ by using Plackett-Burman design, and influences of HCl concentration, AlCl₃ concentration, reaction temperature, reaction time, and liquid-to-solid ratio on fluorine leaching rate were investigated. It is found that the fluorine in barite mainly exists in the form of disseminated and banded fluorite. By using HCl at a concentration of 3 mol/L and AlCl₃ at a concentration of 0.4 mol/L, after 30 min leaching reaction of ore sample with grain size of 48-75 μm, liquid-to-solid ratio of 10 mL/g, and stirring speed at 300 r/min, the leaching rate of fluorine can reach 93.20%, and the mass fraction of barite is 95.91%. Results show that all factors that influence fluorine leaching rate are arranged in descending order of importance as follows: reaction temperature > HCl concentration > reaction time > AlCl₃ concentration > liquidto-solid ratio.

Ginkgo biloba biochar-based fertilizer prepared with Ginkgo biloba was used for remediation of heavy metal contaminated soil. After 4 d remediation at 30 ℃ by adding 4% ginkgo biloba biochar-based fertilizer, the stabilization efficiencies of Pb, Cd, and Cu can reach 89.5%, 97.5%, and 74.9%, respectively. It is shown that the contents of acid extractable Pb, Cd and Cu decrease from 43.81%, 60.53% and 65.31% to 12.21%, 52.75% and 60.47% respectively; the contents of reducible Pb and Cd decrease from 11.12% and 36.35% to 10.02% and 33.71% respectively; the contents of oxidizable Pb and Cd decrease from 14.36% and 0.76% to 11.61% and 0.74%, respectively, while the content of oxidizable Cu increases from 11.13% to 14.12%; the contents of residual Pb, Cd, and Cu increase from 30.71%, 2.36%, and 22.33% to 66.16%, 12.80%, and 24.19%, respectively. It is concluded that with strong stability and a good remediation effect at low cost, such ginkgo biloba biochar-based fertilizer shows a good application prospect in remediation of heavy metal contaminated soil.

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.

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.

Based on studies on the chemical phase-analysis methods for rubidium in some mineral ores from Hunan Shizhuyuan mine, the occurrence state and mass fraction of rubidium in minerals were preliminarily determined by using inductively coupled plasma optical emission spectrometer (ICP-OES), combined with XRD, SEM, electron probe and MLA. After the phase separation of rubidium was determined and appropriate selective reagents and reaction conditions were selected, rubidium in mica, rubidium in fluorite, rubidium in silica-aluminum oxide, rubidium in feldspar, and rubidium in insoluble minerals were all analyzed. Then, a method for rubidium phase analysis was developed. It is found that this analysis method is characterized by lower detection limit, high precision, good reproducibility, wider linear range, and simple and rapid process. Based on an experiment on the interference of alkali metallic elements in minerals, reasonable analysis methods were selected according to different concentrations of K, Na and Li, so as to obtain accurate results with less interference.

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.

In view of problems of low conversion and low productivity in preparation of benzoquinone by the oxidation of aniline, a leaching process with a shear-enhancement approach was adopted to investigate the effects of adding amount of pyrolusite, acidity, shear rate, and liquid-solid ratio on the conversion rate of p-benzoquinone. It is found that high-speed shearing can accelerate the homogenization of pyrolusite and aniline, and enhance the oxidation reaction, resulting in efficient conversion of aniline. Under optimized process conditions, including acidity of 90 g/L, shear rate of 2 500 r/min, liquid-solid ratio of 5∶1, pyrolusite addition at 1.6 times theoretical amount, the conversion rate of p-benzoquinone is 91.23%. Compared to traditional mechanical stirring process, the reaction time can be significantly shortened and the conversion rate of p-benzoquinone can be significantly increased. It is concluded that the leaching process with shear-enhancement approach can have a promising future in industrial application.

With coal-based carbon as a hard template and zinc acetate as zinc source, a kind of ZnO nanomaterial with excellent crystal structure and pore properties was synthesized by adopting high-temperature roasting process. Then, the sensitivity of a gas sensor based on this ZnO nanomaterial to ethanol gas was investigated. The results are shown as follows: such ZnO sensor at 200 ℃ presents higher sensitivity to lowly-concentrated ethanol gas, with a response value of 5.25; the response time and recovery time of the ZnO sensor to the ethanol gas with concentration of 1×10^-5 are 10 s and 6 s respectively; the ZnO sensor has its sensitivity to ethanol gas in a linear relationship with the concentration of ethanol gas, and can detect the lowest concentration level of 1×10^-7; the ZnO sensor has a lower sensitivity to those kinds of gas, including acetic acid, methanol, ammonia and methane. Due to its higher sensitivity to ethanol gas, it is concluded that such sensor presents excellent selectivity in gas detection.

Effect of step quenching at different temperatures on mechanical and corrosion properties of Al-Mg-Si-Cu alloy was explored by carrying out room temperature tensile test, intergranular corrosion test, electrochemical corrosion test, as well as by means of transmission electron microscopy (TEM). It is found that the alloy, after 60 minutes of step quenching at 100 ℃ followed by 28 days of natural aging, can not only maintain a low yield strength of 162.49 MPa and a high strengthening increment of 105.60 MPa, but also exhibit a 57.2% reduction in intergranular corrosion depth compared to water-quenched alloy. TEM and EDS analyses show that type II Mg-Si clusters formed during step quenching effectively inhibit type I clusters formed during natural aging, while promote precipitation of intergranular β″ phase and β′ phase. Moreover, the precipitated phase at grain boundary is coarse and spherical with discrete distribution due to depletion of nearby solute atoms.

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.

In view of low prediction accuracy and slow speed of traditional prediction methods for strip crown, a weighted prediction model based on random forest (RF) and support vector machine (SVM) was established. The parameters of models based on RF, SVM, and a combination of RF and SVM were optimized respectively by adopting the improved coati optimization algorithm (ICOA), so as to improve crown prediction accuracy. A 1 580 mm production line of a hot-rolling mill in one company was taken in a simulation research on crown prediction based on its actual measurement. The root mean square error of the weighted prediction model based on RF and SVM is 2.23 μm. It is found that this weighted prediction model has its prediction accuracy increased by 7.08% and 2.62% respectively, compared with the models based on RF and SVM respectively.

A composite photocatalyst of TiO₂-CNTs was synthesized by adopting the sol-gel method and ultrasonic dispersion, and then its activity in the photocatalytic reduction of CO₂ was tested. With a load capacity of carbon nanotubes (CNTs) at 0.75%, the TiO₂-CNTs present a better performance in photocatalytic CO₂ reduction. Under UV irradiation with wavelength of 365 nm, the average yield of CH₄ and CO from the composite catalyst are enhanced by 90% and 156% respectively, compared to the usage of single TiO₂ catalyst. It is believed that the reaction is based on the following mechanisms: CNTs, as a co-catalyst, forms a compact electron transport structure with semiconductor of TiO₂, which significantly accelerates the transfer of photogenic carriers and reduces the electron-cave recombination efficiency. In addition, high specific surface area and excellent adsorption performance of CNTs can increase active sites for reaction, thus improving efficiency of photocatalytic reduction of CO₂ by the catalyst.

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, 1443.8, 1386.4, 1341 and 1276.2 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.

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.