The basic flow of Midrex and HYL/Energiron technologies for direct reduction in a shaft furnace and the direct reduced iron output by each processing technique in recent years are firstly introduced, and then the equipment, raw materials and process characteristics of those two technologies are analyzed based on comparison. Based on the expounding of technical R&D and investment of global steel companies in these two technologies, it is pointed out that the development of hydrogen-based direct reduction process in a shaft furnace is closely related to grade of pellet ore, heat adsorption during hydrogen-based reduction reaction process, technologies for large-scale green hydrogen production and production cost among others. It is important for sustainable development of Chinese iron and steel industry to adopt hydrogen-based direct reduction in a shaft furnace that conforms to the national conditions.

As for the open-pit slope with fault structure, studies on its deformation and failure characteristics were carried out by means of remote sensing images, field investigation and numerical simulation, and its safety factor was also calculated, so as to explore the influence of fault structure on slope stability. Then, based on the analysis of deformation and failure process of slope, the failure rule for open-pit slope with fault structure was discussed. It is found that the landslide hazard occurring on the north slope of the open-pit mine is attributed to an internal factor of fault structure combined with an external factor of unloading by underground mining. Under the combined action of disturbance by underground mining and cutting by F15 fault, a landslide is prone to occur along the fault structure, and then the failure zone will be gradually expanded. The deformation and displacement of upper slope above the F15 fault structure becomes relatively larger, and proceeds towards the eastern bottom along the F15 fault structure. The F15 fault structure changes the deformation and failure trend of the upper part of the northern slope. It is shown that when the safety factor of open-pit slope is 1.45, F15 fault zone is the potential sliding plane, and no larger deformation has occurred along the fault zone of the northern slope.

Based on the engineering geological data and the anchoring support scheme for a foundation pit, a three-dimensional geological generalization model was constructed with ANSYS software for the foundation pit of one bridge over the Yangtze River. This model was then imported into FLAC^3D to simulate and analyze the stress, deformation and plastic zone evolution characteristics of the foundation pit during the process of excavation and anchoring support. The results show that during the excavation of the foundation pit, the rock mass is generally subjected to well-distributed compression, with less concentrated stress. After excavation, the foundation pit generally appears to have an upward rebound deformation, with the displacement of bottom plate maximally reaching 14.7 mm. It is shown that the counter-trend slope on the north side has the maximum deformation up to 8.65 mm. The volume of the plastic zone continues to increase, and then decreases during the excavation of the last step. After the excavation is completed, a large number of plastic zones appear in the rock mass on the north side of the foundation pit. Compared to the support scheme with only anchor rods, the support with anchor rods together with anchor cables can make the deformation of the rock mass of slope on the north side reduced by 16.6% on average, as well as the volume of plastic zone reduced by about 8 600 m³ and the distribution depth reduced from 15 m to 5 m after excavation is completed. It is concluded that the support scheme with both anchor bolts and anchor cables can not only effectively suppress the deformation of the slope on the north side, but also effectively reduce the distribution depth of plastic zone in the rock mass and improve the stability of rock mass, presenting better support effect for the foundation pit slope.

Based on comparison of cadmium immobilization with 4 types of minerals originated from 14 places in Hunan Province, four kinds of natural and efficient remediation materials (including limestone from Yujiaao of Ningxiang County, low-grade manganese ore from Nanmuchong of Xiangtan County, bentonite from Mazongling of Taoyuan County, and sepiolite from Xingang of Shimen County) were selected. The kinetic rate of cadmium immobilization by these four natural minerals is in the following descending order: bentonite > limestone > sepiolite > manganese ore. The cadmium adsorption by four kinds of minerals increases as the initial cadmium mass concentration increases. With cadmium mass concentration no higher than 10.0 mg/L, the cadmium adsorption by these four minerals is in the following descending order: limestone > bentonite > manganese ore > sepiolite; with cadmium mass concentration exceeding 10.0 mg/L, the cadmium adsorption by these four minerals is in the following descending order: bentonite > limestone > manganese ore > sepiolite. The adsorption behavior follows Langmuir adsorption model, and the maximum adsorption capacities of bentonite, limestone, manganese ore and sepiolite are 29.38 mg/g, 14.51 mg/g, 9.67 mg/g and 5.27 mg/g respectively. With pH of solution within the range of 6 to 9, the removal efficiency of cadmium by four minerals is in the following descending order: limestone > bentonite > manganese ore > sepiolite. It is concluded that the cadmium immobilization with natural minerals is related to chemical composition of minerals, initial cadmium mass concentration, and pH value.

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.

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.

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.

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.

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.