The typical fluoride-containing spent cathode from aluminum electrolysis industry is usually hard to be disposed, and a processing technique combining roasting and water leaching was adopted to remove fluorine in the spent cathode. The effects of parameters, including dosage of defluorination agent, roasting temperature, roasting time, liquid-solid ratio for water leaching, and water leaching time, on the fluorine content in water-leached residues were investigated. The results show that after 60 min roasting at 600 ℃ with 25% defluorinating agent, and 30 min water leaching with liquid-solid ratio of 8 L/kg, the leaching residue contains 1.12% fluorine and is mainly composed of carbon, calcium fluoride and sodium silicate aluminate, without leaching toxicity, which is ordinary solid waste. It is concluded that the processing technique consisting of roasting and water leaching can effectively remove fluorine from typical fluoride-containing spent cathode.

By adopting coal-based hydrogen metallurgy technology, nickel smelting slag was ground to-0.038 mm (90.02% passing size), and magnetite concentrate was added for oxygen regulation. Coal-containing pellets were prepared with nickel slag, magnetite concentrate, Guanghui coal and bentonite at a mass ratio of 100∶10∶26∶2, a roasting temperature within 1 280-1 300 ℃ and roasting time of 35 min. A reaction between hydrogen-rich gas produced by the pyrolysis of high-volatile coal and the water gas resulted in a strong reduction coupling effect. The results show that the metallization rate of pellets reaches 92.91% and the iron content in magnetic separation concentrate is 85.80%. It is concluded that this technology significantly optimizes the reduction kinetics of nickel slag, providing a new route for the efficient utilization of iron resources in nickel slag.

Al-Cu-Mg-Ag alloy sheets prepared at different hot rolling temperatures (450 ℃ and 470 ℃) were annealed at 340, 360, 380 and 400 ℃ respectively. Subsequently, room-temperature tensile tests, fatigue crack growth tests, metallographic microscope, scanning electron microscope (SEM) and X-ray diffraction (XRD) were employed to investigate the effects of hot rolling and annealing processes on the microstructure and mechanical properties of the T4-tempered alloy. The results indicate that temperatures of hot rolling and annealing exert little influence on the room-temperature mechanical properties and fatigue crack growth rate of T4-tempered Al-Cu-Mg-Ag alloy. Hot rolling at elevated temperatures leads to the increase in the amount of static precipitates, which can in turn result in finer recrystallized grains during the subsequent annealing process.

To optimize the electrochemical performance of lithium manganate (LMO) cathode materials, metal oxides (SnO₂, ZrO₂, La₂O₃, TiO₂) were employed for the coating modification of LMO cathodes. The results show that metal oxide coatings do not change the basic morphology and spinel octahedral structure of LMO cathode materials. The SnO₂-coated cathode material (SnO₂@LMO) exhibits better electrochemical performance than those coated with other oxides. SnO₂@LMO delivers an initial discharge specific capacity of 109.87 mAh/g at 1C rate, with a capacity cycle retention rate as high as 98.01%. At high rates, it shows slower capacity fading and superior rate capability. CV and EIS analyses confirm that the SnO₂ coating forms a stable initial interface, enabling SnO₂@LMO to maintain good reversibility after cycling. SnO₂@LMO has both the lowest surface film resistance (R_s) and charge transfer resistance (R_ct), delivers optimal interface stability and charge transfer kinetics.

A non-intrusive indirect pressure estimation and early warning is proposed for high-pressure water-jet pipelines. The EfficientNet deep learning model is employed to evaluate the quality grade of steel plate surface before and after cleaning based on the images. Observable sequences are constructed by the quality grades and system-set pressure. A hidden Markov model (HMM) is then adopted to capture the latent mapping between such sequences and the pressure states of water-jet pipelines, and the pressure state sequences are decoded. Based on the characteristics of the decoded sequences, abnormal pressure can be detected and warned. Industrial experiments demonstrate that the proposed method can achieve an accuracy of 91.2% and an F1 score of 88.3% in abnormal pressure detection, with performance significantly superior to that of the threshold-based method and logistic regression. This method is of practical guiding significance for the intelligent operation and maintenance of high-pressure water-jet equipment.

With titanium and hexagonal boron nitride powders as raw materials, TiN-TiB₂ composites were fabricated via spark plasma sintering (SPS), and the effects of sintering holding time on the microstructure and mechanical properties of the composites were investigated. The results indicate that at a sintering temperature of 1 600 ℃, with pressure of 50 MPa and holding time ranging from 10 min to 20 min, the prepared TiN-TiB₂ composites consist of TiN and TiB₂ phases. As holding time increases from 10 min to 20 min, the interfacial bonding between phases is strengthened and atomic diffusion becomes more sufficient. Consequently, grains grow gradually and exhibit a more regular morphology. The mechanical properties of the composite firstly increase and then decrease with prolonged holding time, closely correlated to grain growth. With holding time of 15 min, the composite presents optimal mechanical properties: its hardness, flexural strength and fracture toughness reach (21.5±0.18) GPa, (618±18) MPa and (5.45±0.07) MPa·m^1/2, respectively.

By using manganese nitrate and trimesic acid, Mn-MIL-100 powder precursor was chemically synthesized via a solvothermal reaction with methanol as the solvent, and then subjected to heat treatment to obtain MnO-loaded porous carbon materials. It was found that MnO particles were successfully loaded on the MOF-derived porous carbon skeleton. The maximum current density of the oxidation of the MnO catalyst-loaded battery was 5.7 times that of conductive carbon. Long-term cycling tests showed that the MnO@MOF/S battery delivered an initial capacity of 683.6 mAh/g with a retention rate of 62.1% after 500 cycles, presenting a Coulombic efficiency as high as 99.2%.

To achieve high-value utilization of silicon monoxide tailings (SiO-W), SiO-W@G composite anode materials for Li-ion batteries were prepared by granulating the composite of SiO-W and graphite with pitch as a binder, and their electrochemical performances were then compared with those of conventional SiO@G anode materials. The results show that SiO-W@G, with particle size (D₅₀=11.390 μm), is smaller than SiO@G (16.831 μm) and has larger specific surface area (15.66 m²/g vs. 10.80 m²/g), but both have the same tap density (0.99 g/cm³). SiO-W is uniformly composited with graphite, and there is no obvious difference in crystal structure. Electrochemical tests show that SiO-W@G delivers a specific capacity of 443.55 mAh/g and an initial coulombic efficiency of 85.56%, which are close to those of SiO@G (463.65 mAh/g, 86.39%). It is concluded that the granulation of composite can effectively enable the high-value utilization of silicon monoxide tailings, presenting good prospects for industrial application.

Based on cyanide-free electroplating technology for hard gold plating, with ethanol as an anti-solvent for precipitation of sodium gold sulfite (Na₃Au(SO₃)₂), a process was developed for preparing Na₃Au(SO₃)₂, consisting of non-aqua regia gold dissolution and sodium sulfite complexation and precipitation with ethanol. Then, a cyanide-free formula for hard gold electroplating with good comprehensive performance was optimized. With the sodium gold sulfite-sodium sulfite-EDTA-2Na as the plating system, the effects of different additives on bath and plating properties were investigated, and the metal turnovers (MTO) of the bath was also verified. The results show that an addition of sodium dihydrogen phosphate can increase the limiting current density but greatly reduce the electroplating efficiency; while an addition of ethylenediamine can obviously improve the deposition rate, and the obtained plating remains bright at the current density of 3 mA/cm². In an experiment by employing the proposed electroplating technology with two addititives, a plating was prepared with a microhardness of 100HV-140HV, presenting dense structure with low porosity. The current efficiency of electroplating was above 98% and the MTO of bath exceeded 6. The bath system exhibited weak cathodic reaction.

To investigate the motion characteristics of deep-sea polymetallic nodules in a vertical pipeline of airlift system with air at different flow rates and also study flow field characteristics of gas-liquid-solid three-phase flow in the system, numerical simulation was made with CFD-DEM coupling method for the three-phase flow in the vertical pipeline of airlift system. The results show that as air flow rate increases, the average local volume fraction of particle swarm decreases, and the frequency of occurrence is lower first and then become higher for slug flow. Both the flow rate of fluid and the average axial velocity of particle swarm in pipeline increase. The pressure drop in the pipeline increases with the local volume fraction of particle swarm, and average pressure drop decreases with the increase of air flow rate. Therefore, based on the variation in local volume fraction of particles in pipeline reflected by the pressure drop, the slug flow can be identified so as to prevent pipeline blockage.