In order to explore the formation mechanism of landslides and reveal the development process of landslides, Mayang Miao Autonomous County in Hunan Province was taken as an example, and landslide analysis was conducted for red beds area in Hunan Province based on susceptibility to the selected factors causing disasters, including elevation, slope, terrain ruggedness index (TRI), stratum lithology and distance away from faults, among others. It is found that landslide occurrence is well correlated with several factors, with susceptibility to each factors in the following descending order: type of land use>elevation > TRI > normalized difference vegetation index (NDVI) > distance away from roads > slope > stratum lithology > distance away from rivers > average rainfall during recent several years > distance away from fault, and the corresponding factors with high sensitivity are listed as follows: land used for buildings, elevation [101 m, 1 394 m), TRI[47 m, 74 m) and NDVI[0.30, 0.43).

An experiment was conducted on selective extraction of lithium by co-pyrolysis of spent NCM cathode powder and polypropylene followed by water leaching, and the obtained pyrolysis products were characterized. In the experiment, co-pyrolysis of NCM cathode powder with 40% polypropylene ran at 550 ℃ for 2 h, with argon flow rate at 200 mL/min, and then the obtained pyrolysis product was subjected to water leaching, resulting in the lithium leaching rate of 87.92%. It is found that lithium loss is mainly attributed to the formation of water-insoluble lithium cobalt oxide during co-pyrolysis.

A low-grade high-sulfur copper ore from Anhui Province has a sulfur grade of 41.30% and a copper grade of 0.53%. It is difficult to control the flotation index of this easy-to-oxidize ore. To improve the Cu/S separation effect, the influence of grinding fineness, reagent type and reagent dosage on copper flotation index was investigated. A closed-circuitflotation process including one stage of roughing, two stages of cleaning and two stages of scavenging was adopted to treat the ore with a grinding fineness of 83.88% -0.074 mm, with CaO and Na₂S as a combined depressant, Z-200 as the collector and terpenic oil as the frother. It is found that a copper concentrate grading 15.27% Cu at 80.96% recovery can be obtained. This experimental study can provide a reference for flotation separation of copper from low-grade high-sulfur copper ore.

In order to explore influence of the thickness of barrier pillars reserved in stopes on mining operation during the transition from mining with caving to mining with backfilling in a copper-zinc mine in northwest China, six thickness schemes were selected for the barrier pillars in the stope based on the mining status and the engineering geological conditions. Then, a three-dimensional numerical model was constructed with 3Dmine-Rhinoceros, and factor of safety and zone safety were adopted in the analysis. As for the mind-out area without backfilling in the middle section of upper part, three continuous stope interval mining on the level of 210 m was calculated based on simulation with FLAC^3D, and the changes in roof settlement deformation, factor of safety and zone safety were also analyzed for the barrier pillars left with different thickness after mining. It is found that with the barrier pillars of 12 m in thickness, the stability of stope can be ensured during transition of mining. Thus, it is recommended that the thickness of reserved barrier pillars be no less than 12 m.

Aiming at obvious elastic-plastic deformation of diamond drill bits in the process of drilling marine gas hydrate, a modeling approach that is suitable for the core drilling process of drill bits was proposed based on the Hertz theory. Firstly, the rock-breaking mechanism was analyzed for marine gas hydrates from elastic deformation to elasticplastic deformation during the drilling process under sea, and the drilling pressure and cutting force of single diamond particle on the diamond bit during the drilling process were calculated. Secondly, according to the stress condition of a single diamond particle, the theoretical relationships between drilling pressure and torque on the whole bit and other drilling parameters were obtained, and a mechanical model was established for the diamond drilling bit. Finally, a relationship curve between the saturation of marine gas hydrate and the torque and drilling pressure was obtained based on analysis. An at-sea testing by adopting such method has successfully taken some samples of marine gas hydrate, which has verified the feasibility of this method. This research provides a theoretical reference for the design of drill bit parameters and optimization of efficient deep-sea core drilling operation.

Sn-Sb-Cu-Fe-Zn high-entropy alloy nanoparticles were uniformly anchored on conductive interconnected carbon nanofibers by electrospinning in combination with calcination process, and a composite anode material of SnSbCuFeZn@CNFs for lithium-ion batteries was successfully synthesized. Research shows that calcination temperature has an important influence on the phase composition and morphology characteristics of the synthesized material, and directly affects the crystal phase, size and distribution of Sn-Sb-Cu-Fe-Zn high-entropy alloy nanoparticles, also determines the electrochemical performance of SnSbCuFeZn@CNFs electrode. In the studied samples, the SnSbCuFeZn@CNFs-900 electrode can present excellent comprehensive performance: it delivers an initial specific discharge capacity of 1 232.8 mA/g at 0.1 A/g, and has reversible specific discharge capacity retaining at 786.0 mA/g after 200 cycles; it delivers a specific discharge capacity of 433.8 mA/g after 500 cycles at 1.0 A/g; it is found that the pseudo-capacitance accounts for as high as 93.37% at a scanning speed of 2.0 mV/s.

An experimental study was carried out for adsorption of ammonia nitride and copper ions in electroplating wastewater by fly ash-based zeolite. Results show that the proper conditions for adsorption of copper ions by fly ash-based zeolite include pH of 8, initial mass concentration of 200 mg/L for copper ions in the solution, adsorption time of 0.45 h, and temperature of 200 ℃; the proper conditions for adsorption of ammonia nitride by fly ash-based zeolite include addition of 8 g/L fly ash-based zeolite, pH of 8, adsorption time of 0.60 h, and initial mass concentration of 150 mg/L for ammonia nitride in the solution. It is found that the adsorption of copper ions by fly ash-based zeolites is a physical adsorption process, and the adsorption of ammonia nitride by fly ash-based zeolites is a combination of ion exchange and physical adsorption.

Red mud was pre-treated with process of reduction roasting followed by magnetic separation, and the obtained non-magnetic material was calcined and then dissolved in hydrochloric acid. After that, it was filtered after addition of saturated sodium meta-aluminate polymerizing agent, and then matured to prepare polymeric aluminum chloride (PAC) base liquid, which was used in a purification test. With PAC-base liquid and manganese-containing wastewater in a volume ratio of 1∶120, stirring speed of 140 r/min, pH of 8, reaction temperature of 30 ℃, and addition of polyacrylamide (PAM) at an amount of 20 mg/L, the manganese mass concentration in the wastewater reduced from 325.3 mg/L to 1.5 mg/L after 5 hours of settlement, showing manganese removal rate up to 99.5%. It is shown that the manganese mass concentration in the purified liquid can meet class Ⅰ limit in the national discharge standard.

A kind of low-impurity lead electrolyte was prepared with lead ingots, fluorosilicic acid, hydrogen peroxide, bone glue, and β-naphthol as raw materials, and then was used in an experimental research on 14 consecutive cycles of electrolysis to produce refined lead. It is shown that the initial power consumption of lead electrolysis was 52.37 kW·h/t, and 6N high-purity lead was produced in the first two cycles; as the cyclic electrolysis process proceeded, the impurity content and lead ion content in the electrolyte gradually increased, while the mass concentration of fluorosilicic acid gradually decreased, resulting in an increase in the impurity content of precipitated lead. Therefore, the content of Cu, Ag, Fe, Al and other impurities in the precipitated lead all gradually increased after two cycles of electrolysis, and the precipitated lead met the standard for 5N but did not meet the standard for 6N high-purity lead. Furthermore, the power consumption also gradually increased, but remained at a low level of 50 kW·h/t to 70 kW·h/t for each cycle.

With a flake graphite ore from Africa as the raw material, a beneficiation technique was adopted to recover graphite resource according to ore size fraction. The results show that the fixed carbon content of the graphite feed ore is 32.54%, and the large flake graphite mainly in sheet or banded structure is intergrown with feldspar minerals. The optimized roughing condition is determined as follows: grinding fineness of -0.074 mm 72.87%, kerosene dosage of 50 g/t and terpineol dosage of 150 g/t. A flotation process with one stage of roughing, one stage of scavenging and four stages of cleaning is adopted, in which the large flake graphite is screened from the flotation production of the 1st-stage of cleaning, while the undersize is treated further by three stages of grinding and three stages of cleaning to recover fine flake graphite. The closed-circuit test shows that the fixed carbon content in the large flake graphite (+0.150 mm) concentrate and the fine flake graphite (-0.150 mm) concentrate reaches 96.53% and 96.21%, respectively. The recovery rate of the large flake graphite reaches 22.74%, which is higher by 7.66 percentage points compared to that by conventional regrinding-separation approach.