With an increase in Ni content, the capacity of high-nickel layered metal oxides (LiNi_xMn_yCo_1-x-yO₂ (0.8≤x<1, NCM) greatly decreases. In view of such problem, it is proposed that singly-crystal NCM cathode material be modified by dual SiO₂@Li₂SiO₃ coating to improve its electrochemical performance. During the synthesis process, the reaction of can consume the residue lithium on the material surface, thus improving diffusion kinetics of interface lithium ions and inhibiting side reaction at the interface. It is shown that the modified cathode material delivers a specific discharge capacity of 156.88 mAh/g after 120 cycles, with capacity retention rate of 70.52%.

With the coal tailings from the flotation process of a coking coal preparation plant in Guizhou as the research object, the effects of four kinds of frother including methyl isobutyl methanol (MIBC), sec-octyl alcohol, terpenic oil and n-pentanol on the flotation performance of coal tailings were investigated. The test shows that the flotation indices of MIBC frother were better than those of the other three frothers with the similar dosage. A flotation process consisting of one stage of roughing, one stage of cleaning and one stage of scavenging was adopted to treat the raw coal with the ash content of 56.90%, and with dosages of kerosene and MIBC respectively at 1 000 g/t and 350 g/t, a qualified coking coal with the ash content of 11.47% and the yield of 32.03% can be produced. The results of foaming ability and foam stability measured by inflation method show that the foaming ability and foam stability of terpenic oil are the strongest, while those indices of n-pentanol are relatively weak, and those of MIBC and sec-octyl alcohol moderate. The characterization of the adhesion process between bubbles and coal particles under the action of different frothers analyzed with bubble-particle encapsulation angle and induction time measuring instrument suggests that MIBC can enhance coal-carrying capacity of bubbles, shorten particle-bubble induction time, thus bringing improved flotation effect.

A method of selective adsorption and recovery of gold from waste thiourea liquid with biomass-based adsorbent prepared from phyllostachys pubescens was proposed. The charcoal, after being activated in H₂O-CO₂ atmosphere, has more nanopores with smaller size on its surface, compared to being activated by CO₂ alone, which greatly increases the specific surface area of the adsorbent material. Based on exploration of the effects of factors, including type of adsorbent material, pH value, adsorbent dosage, adsorption temperature, and adsorption time, on the adsorption of gold in waste thiourea liquid, the appropriate adsorption conditions were obtained as follows: pH of 6, adsorbent dosage of 8 g/L, adsorption temperature of 25 ℃, and adsorption time of 3.5 h. It is found that activation in H₂O-CO₂ can bring the activated carbon with better adsorption effect, and the removal rate of gold from waste thiourea liquid by adsorption can exceed 96%. The adsorption isothermal model is used to fit the process of gold adsorption from waste thiourea liquid by the carbon activated in H₂O-CO₂ atmosphere, and the results show that such gold adsorption process follows Freundlich model and is a physical adsorption process.

For discussing rational sequence of drift stoping by cemented backfilling under complex stress conditions, with No.2 mine of Jinchuan Group as an example, a three-dimensional numerical model was constructed with a numerical simulation software, and was then used to analyze the stress field, displacement field and plastic failure zone in drift stoping with different sequences. On this basis, the drift stoping sequence, after optimization by adopting a combined weighting and fuzzy comprehensive evaluation, was then adopted in an on-site industrial experiment. The results show that both mining sequence by overhand or underhand stoping and drift stoping with different spatial sequence can bring a certain influence to the maximum principal stress, maximum tensile stress, vertical displacement, plastic failure zone, as well as the maximum principal stress and vertical displacement in the next stope nearby; mining sequence of underhand stoping followed by overhand stoping, or firstly drift stoping of vertical ore mass, can make the overall mining with higher safety. The on-site experiment with such mining sequence presents better effect. It is concluded that this research can provide some reference in the design and optimization of mining sequence for drift stoping by cemented backfilling under complex stress conditions.

To improve the interfacial stability of spinel phase LiNi_0.5Mn_1.5O₄ cathode material in deeply charged state, a nanoscale Al₂O₃ film was deposited on the surface of single-crystal LiNi_0.5Mn_1.5O₄ by atomic layer deposition in a controlled manner. The modified cathode material exhibits excellent long-cycle performance and corrosion resistance (with capacity retention rate up to 94.7% after 500 cycles at 1C). The surface and interface analysis shows that the nanoscale Al₂O₃ coating deposited by atomic layer deposition technology can significantly inhibit the corrosion reaction between material and electrolyte, and also constrain the irreversible dissolution and precipitation of transition metal ions. In addition, AlF₃ produced by HF surface etching can enhance corrosion resistance of LiNi_0.5Mn_1.5O₄ cathode material, which can thus improve its long-cycle performance and the service performance at high voltage.

Flash flotation technique was introduced to an experiment to recover crystalline graphite. The influence of impeller speed, superficial aeration rate and foam layer thickness on the flash flotation indices of graphite was investigated. The results show that flotation with impeller speed of 750 r/min, superficial aeration rate of 0.3 m³/(m²·min) and foam layer thickness of 20 mm can bring a better flotation performance of graphite. According to the particle size analysis and microscopic observation analysis of concentrate, the flash flotation displays good recovery of the graphite in a particle size range of 0.074-0.180 mm, which is dominated by flake graphite monomer and rich intergrowth. As the flash flotation technique favors the collection of useful minerals from the classification underflow in advance, the probability of overgrinding can be reduced and the flake morphology can be therewith reserved. Therefore, flash flotation technique is expected to be commercially applied in the flotation recovery of crystalline graphite.

A cathode material (NaNi_0.5Mn_0.5O₂) for sodium-ion batteries was synthesized by adopting solid-state, co-precipitation and sol-gel methods, and the effects of synthesis methods on crystal structure, microscopic morphology and electrochemical performance of the cathode material were also explored. The results show that the materials synthesized respectively by those three methods all have O3-type structure, but exhibit different morphology. The cathode material synthesized by solid-state method has a special layered structure, which is conducive to sodium ion de-intercalation. The cathode materials synthesized by solid-state, co-precipitation and sol-gel methods, respectively, deliver an initial specific discharge capacity of 96.1 mAh/g, 92.8 mAh/g and 92.3 mAh/g at 0.1C, with retention rate of 64.3%, 46.5% and 36.5% respectively after 100 cycles at 0.5C. It is concluded that the solid-state synthesis is an appropriate method.

The factors and reasons influencing lime activity are presented, and the influencing mechanism of lime activity for digestion performance of bauxite is also expounded. It is found that the particle size of limestone and calcination temperature are two important factors influencing activity of lime. At a calcination temperature of 1 000 ℃, the activity of lime is as high as 33.5 mL, while with the particle size of limestone increased to 17.5-22.5 mm, the activity of lime increases to 46 mL. The analysis results of scanning electron microscopy show that highly active lime has fine particles with uniform particle size and in a structure of honeycomb with well-developed and interconnected pores. The experiment of bauxite digestion shows that the activity of lime and its adding amount will bring influence to the digestion rate of bauxite and the phase composition of red mud. By adding highly active lime with a C/S ratio of 1.0, the relative digestion rate of bauxite is as high as 98.12%.

An experimental study was carried out on fluoride removal from the wastewater after acid leaching process in one enterprise. In the experiment, zirconia was used in the 1^st-stage reaction and amorphous aluminum hydroxide was adopted in the 2^nd-stage reaction for fluoride removal, and effects of reaction temperature, reaction time and adding amount of zirconia-based reagent on the fluoride removal effect were explored. It is found that both higher temperature and longer reaction time can promote fluoride reduction effect of fluoride removing reagent.1^st-stage reaction ran for 50 min at 75 ℃ with an addition of 50 g/L zirconia-based reagent, the fluoride reduction rate was up to 96% and fluoride mass concentration in the wastewater was reduced from 600 mg/L to 25 mg/L. After that, 2^nd-stage reaction at 70 ℃ ran for 60 min, by adding 5 g/L amorphous aluminum hydroxide, the fluoride mass concentration in the wastewater was down from 25 mg/L to 6.5 mg/L. It is shown that the residue left after fluoride removal process has a good crystal structure and obvious diffraction peak. XRD analysis shows that Na₃AlF₆ is the main component in the residue.

TiO₂ was coated on the surface of LiMn₂O₄ by thermal decomposition of titanate coupling agent, and the effects of coating treatment on the structure and electrochemical performance of LiMn₂O₄, as well as material structure in the cycling were all explored. The results show that TiO₂ can be uniformly coated on the surface of the LiMn₂O₄ by thermal decomposition of titanate coupling agent at 550 ℃. Surface coating does not change the crystal structure of LiMn₂O₄, but obviously improves its electrochemical performance, especially high temperature rate performance and cycle performance. At 55 ℃, LiMn₂O₄ with TiO₂ coating delivers a specific capacity of 75.34 mAh/g at 5C, which is higher than that without coating (43.05 mAh/g). After 150 cycles, the capacity retention rate of the material with TiO₂ coating and without coating is 77.27% and 62.85%, respectively. The improvement of electrochemical performance is attributed to reduction of Mn dissolution in the cathode material by TiO₂ coating, which thus inhibits the change of crystal structure during cycling process, reduces the electrode polarization and charge transfer impedance, as well as improves the charge-discharge reversibility of the material and the Li⁺ diffusion.