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.

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.

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.

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.

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.

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%.

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.

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.

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.