After an in-situ leaching of weathered crust elution-deposited rare earth ores with ammonium sulfate, the obtained tailings were taken to explore the variation of water content, pH value, Zeta potential with sampling depth, and then the total nitrogen content, nitric nitrogen, ammonium nitrogen and the main co-existing ions were also analyzed. The results indicate that the tailings samples were all acidic, and both water content and Zeta potential decreased with increasing of sampling depth. The residual ammonium salt in the ore body mainly exists in the form of water-soluble ammonium (11%-33%), and ion-exchange ammonium (59%-87%) in ammonium nitrogen, presenting the highest content in middle layer and the lowest content in surface layer. XRD analysis reveals that the content of clay minerals in the rare earth tailings positively correlated with the content of residual ammonium. In addition, high content of organic matter in the surface layer of the ore body leads to the highest content of co-existing cations Al³⁺ and RE³⁺ in the surface layer; while as for the ore body at deeper position, the content of co-existing cations Al³⁺ and RE³⁺ decreases obviously, and the co-existing anions SO₄^2- and Cl^- present an opposite variation trend.

Due to high oxidation rate of a lead-zinc sulfide ore, the on-site flotation practice presented poor beneficiation indices. In view of this problem, an optimized closed-circuit process consisting of two stages of roughing, two stages of scavenging, one stage of rough cleaning of combined roughing concentrates, two stages of cleaning and two stages of scavenging for roughing concentrates was proposed. With slime (800 g/t) and CD-2 (300 g/t) as pyrite depressants, CD-1 (600 g/t) and water glass (600 g/t) as gangue depressants, sodium sulfide (500 g/t) as a sulfiding agent, copper sulfate (500 g/t) as an activator, butyl xanthate (200 g/t) as a collector, and terpineol oil (21 g/t) as a foaming agent, a closed-circuit flotation test produced a bulk concentrate grading 16.25% Pb and 27.69% Zn with a lead recovery of 65.05% and a zinc recovery of 92.49%. Compared with the previous on-site flowsheet, the Pb grade and Pb recovery are improved by 2.24 percentage points and 9.36 percentage points, while Zn grade and Zn recovery up by 1.57 percentage points and 5.14 percentage points respectively.

For evaluating vibration reliability of Li-ion battery packs used in heavy-duty mining vehicles, ANSYS, finite element software, was adopted to simulate Li-ion battery packs in a heavy-duty mining vehicle and calculate its stochastic vibration. Based on the test performed about random vibration of battery packs, it is found that the first modal frequency of the battery packs is 33.85 Hz, corresponding to the frequency of upper cover of battery packs, which is greater than the external excitation frequency transmitted by frame (30 Hz). thus low-order frequency resonance can be avoided and vibration reliability of the structure can be improved. The calculated stresses in the random vibration of key parts of battery packs, including stiffener, lower box, upper cover and battery brackets, are all lower than the yield strength of the corresponding materials, indicating the structural parts of battery packs meet the requirements for strength reliability. Permanent deformation and damage have not been found in the assembly of battery packs in the random vibration test, verifying the reliability of this simulative computation results.

Base on the study on homogenization behavior of blast furnace slag (BFS) by dynamic viscosity experiment, a kinetic model was constructed for molten slag conditioning process. The homogenization state of BFS was verified and the final granulation effect was analyzed. It is found that the homogenization time becomes shorten first and then prolonged as the addition of conditioner increases, which is the shortest when an addition of conditioner is at an amount of 15.43%. As for BFS with grain size greater than 1.75 mm, the homogenization time increases obviously. As slag temperature increases, the homogenization time is gradually shortened. Based on the comparison with the composition and mineral phases of fully homogenized BFS, it is verified that homogenization is completed when viscosity value becomes stable. The granulated slag particles with size mainly in the range from 1 mm to 2.5 mm present approximately normal distribution, and the homogenized BFS has amorphous phase content higher than 85%, meeting the requirements in the national standard.

Activated carbon derived from coconut shell was prepared as anode material by adopting high temperature pyrolysis and activation. The effects of activation on the structure, morphology and electrochemical properties of coconut shell carbon were investigated by using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The results show that the coconut shell carbon after activation process is highly disordered, and also microporous and mesoporous. It delivers an initial discharge specific capacity of 918.22 mAh/g at a current density of 0.1 A/g, and retains a specific capacity of 447 mAh/g after 200 cycles discharge at a current density of 1 A/g.

Based on an analysis of a trend in global patent application and distribution of patented technologies for second life power batteries, as well as a discussion on the global competition situation and hotspots in R & D of technologies in this industry, the relevant patent application situation in China is analyzed. It is found that the number of applications for patents on second life power batteries in various countries is steadily increasing, and there is still room for improvement. The classification, detection, screening, and evaluation of retired power batteries have always been the hotspots in technical R & D and are still in development, for which the patent applications present stable upward trend. China, as a major source of relevant technologies, has been playing an important role in patent portfolio, which is consistent with global development trends. The applications for patents on relevant technologies are still expected to increase in the future. Therefore, it is recommended that relevant enterprises should intensify their efforts in R & D to seize opportunities in the industry, and also improve the patent portfolio.

A micro- and nano-indentation test was performed for CoCrFeNiMn high entropy alloy. The relationship between the geometrically necessary dislocation (GND) density of CoCrFeNiMn and reciprocal value of real indentation depth (1/h) was obtained under different working conditions, and the influence of elastic factor (Δe) on GND density was also explored. The results show that GND density with the consideration of elastic deformation (ρ_Ge) presents a nonlinear relationship with 1/h, while GND density without the consideration of influence of elastic deformation (ρ_G) has a linear relation with 1/h. Based on the comparison of variation of ρ_G/ρ_Ge with the indentation depth, it is found that the ratio of ρ_G/ρ_Ge is 3-4 when the indentation depth is less than 500 nm, indicating that elastic factor can have an obvious impact on the GND density at shallow indentation. And, the ratio of ρ_G/ρ_Ge is approaching 1 when the indentation depth is up to 3 000 nm. It is shown that as indentation depth increases, dislocation slip gradually dominates deformation.

The impact of large-diameter pressure-relief borehole arrangement and drilling parameters on roadway stability was studied. It is found that arrangement of boreholes in a two-row pattern, compared to boreholes in a single-row pattern, can benefit stress shift and control of roadway deformation. By adopting the arrangement of boreholes in a single-row pattern and a two-row pattern, the deformation at both sides was reduced by 6.05% and 15.44% respectively, and the original maximum stress was reduced from 39.61 MPa to 33.50 MPa and 32.70 MPa respectively. It is also found that boreholes should be arranged, as much as possible, near the center of two sides, penetrating the plastic zone to the place with the maximum stress. And the spacing between boreholes should be determined based on the horizontal distance of the plastic zone of boreholes, and the burden spacing should be less than the height of stress-relaxed zone.

Response surface methodology (RSM) was used to optimize the flocculation settlement parameters of fine iron tailings slurry. According to the Box-Behnken test method in Design-Expert 8.0 software, a three-factor and three-level test was designed to obtain a regression equation of turbidity model for flocculation settlement of fine-grained iron tailings slurry. The results show that with the following favorable flocculation settlement parameters, including addition of inorganic flocculant FeCl₃ at an amount of 113.44 mg/L, organic flocculant PAM at an amount of 0.61 mg/L and stirring speed of 440.57 r/min, the slurry turbidity is predicted to be 11.45NTU, while the measured value is 12.38NTU, indicating that the model has a good accuracy with a small error. Based on the model variance analysis, reliability analysis and factor interaction analysis, it can be verified that RSM is reasonable and feasible to be used for optimizing the flocculation settlement parameters of fine iron tailings slurry, which can provide theoretical basis for its efficient treatment.

A flowsheet consisting of pre-reduction magnetic roasting and magnetic separation was introduced to process a refractory weakly-magnetic iron ore from Jiangsu Province. The results show that after 60 min roasting at 750 ℃ by adding coal as a reducing agent at an amount of 3%, the pre-reduced iron ore was ground to a fineness of 75% -0.074 mm and then subjected to low intensity magnetic separation consisting of one roughing, one cleaning and one scavenging, resulting in a high quality iron concentrate grading 65.05% Fe at 96.19% recovery. The research results can provide technical reference for the mineral processing of refractory weakly-magnetic iron ore.