Based on an introduction of the structural characteristics of single-crystal Ni-rich ternary cathode material, the common preparation techniques of such material are summarized. Besides, the main strategies for improving the performance of this material in recent years are also discussed, which can provide a reference for large-scale production of such high-performance single-crystal Ni-rich ternary cathode material.

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.

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.

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.

LiMn_0.6Fe_0.4PO₄/C (LMFP) composite synthesized by a combined process of co-precipitation and solid-phase sintering not only has low impurity content, uniform phase distribution, but also exhibits excellent electrochemical performance. It is shown that such process can inhibit the formation of Mn₂P₂O₇ phase and improve the lithium ion diffusion rate of LMFP, while removing NH₄⁺ and H₂O. The Li-ion batteries assembled with LiMn_0.6Fe_0.4PO₄/C exhibit excellent electrochemical performance, showing initial specific discharge capacity of 145.5 mAh/g at 1C and 111.9 mAh/g at 5C. It is concluded that this process, being simple and cost-effective, is suitable for industrial production. Such study provides a feasible scheme in designing cathode materials for commercialized high-performance Li-ion batteries.

With manganese sulfate as raw material and hexadecyl trimethyl ammonium bromide as modifier, trimanganese tetroxide was synthesized by complex-precipitation method, with which lithium manganate cathode material was then synthesized by high-temperature solid-state reaction. The effects of modifier amount on the morphology and particle size of trimanganese tetroxide and the specific discharge capacity of lithium manganate cathode material were all discussed. Results show that serious particle agglomeration can occur in the trimanganese tetroxide synthesized without modifier. With 3.0 g/L hexadecyl trimethyl ammonium bromide as the modifier, the synthesized trimanganese tetroxide has uniform particle size, and is dispersed without any agglomeration. Spinel lithium manganate was synthesized with the self-made modified trimanganese tetroxide, and then compared with the spinel lithium manganate synthesized with three kinds of trimanganese tetroxide available on the market. The results show that the lithium manganate synthesized with the self-made modified trimanganese tetroxide can present better electrochemical performance, delivering an initial discharge capacity of 120.43 mAh/g, with a retention rate of 96.79% after 50 cycles at 1C.

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 vanadium pentoxide and citric acid as raw materials, a kind of 3D flower-like VO₂(B) electrode material with large specific surface area and excellent structural stability was prepared by adopting hydrothermal synthesis. The crystal structure and morphology of the VO₂(B) electrode material were characterized by X-ray diffraction, scanning electron microscope, and transmission electron microscope, and the electrochemical properties of VO₂(B) electrode material were measured by constant current charge and discharge, as well as cyclic voltammetry. The results show that the first specific dischage capacity of 3D flower-like VO₂(B) electrode material is 227 mAh/g at a current density of 0.1 A/g. It delivers the first specific discharge capacity of 151 mAh/g at a high current density of 1 A/g, and retains 79.6% of this capacity after 300 charge-discharge cycles, exhibiting a good rate performance.

An overview of progress in the research on anode materials of lithium-ion batteries based on vanadium-based compounds (including vanadium oxide, vanadate, vanadate phosphate and oxide-free vanadium-based compounds) is presented. Furthermore, based on the analysis of relationship among modification method and structure of material and electrochemical performance, it is proposed that vanadium-based anode materials for lithium-ion batteries shall become the trend in the future research.

With silicon material (BFSi) extracted from blast furnace slag as silicon source and polyacrylonitrile (PAN) as carbon source, a kind of silicon-carbon anode material for lithium-ion batteries was synthesized. And the influence of ratio of silicon to polyacrylonitrile on the BFSi@C material was investigated. Results show that BFSi@C synthesized with BFSi and PAN in a mass ratio of 3∶1 delivers an initial charge capacity of 1 884.99 mAh/g at a current density of 0.5 A/g. After 100 cycles, it still delivers a specific charge capacity of 1 509.32 mAh/g, with a capacity retention rate of 80.07%. Moreover, it presents excellent rate performance at high current densities. Compared with commercial silicon materials, BFSi@C demonstrates higher cycle capacity and superior rate performance, delivering a specific capacity up to 538.31 mAh/g at a current density of 5 A/g.

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.

With tetraethyl orthosilicate as silicon source and cetyltrimethylammonium bromide (CTAB) as a surfactant and pore-forming agent, a carbon-coated mesoporous hollow silicon oxide as anode material was synthesized by adopting the modified stöber method and carbonthermal reduction. The results show that different volume ratio of ethanol to water can bring important impact to the particle size, morphology and performance of SiO_x nanospheres. With ethanol and water in a low volume ratio, the obtained nanomaterial has a low sphericity and becomes oval; as the ratio increases, the nanomaterial becomes larger in size; with ethanol and water in a ratio of 0.45, the obtained SiO_x nanospheres are around 300 mm in size. The button batteries assembled with such nanospheres deliver a reversible specific capacity of 813 mAh/g after 200 cycles at a current density of 100 mA/g, and 704 mAh/g after 1 200 cycles at 500 mA/g, retaining 82% of this capacity, with a capacity attenuation rate of 0.015% after each cycle.

The influence of polyether additives on performance of ultra-thin Li-ion battery copper foil with thickness of 5 μm was studied by electrochemistry, scanning electron microscopy, and X-ray diffractometer. The results show that addition of polyether additives into electrolyte can promote negative shift of Cu deposition potential, and polyether additives with suitable concentration can lead to finer grains of copper foil, which is conducive to improving the surface flatness of copper foil. When the mass concentration of polyether additives is 2.3 mg/L, the obtained copper foil has tensile strength of 620.43 MPa, elongation of 3.67%, glossiness of 161 GU, and surface roughness of 1.02 μm, presenting excellent overall performance. The electrolytic copper foil with high tensile strength has a preferred orientation of (111) plane.

An argyrodite-type sulfide solid electrolyte Li₆PS₅Cl (LPSC) was solid-phase synthesized by adopting high energy ball milling in combination with heat treatment. It is found that prolonging ball milling time is conducive to crushing, mixing, grain refinement and amorphization reaction process of raw material powder; increasing sintering temperature is beneficial to the formation of a single pure phase, but too high temperature for sintering can make electrolyte melted and decomposed, leading to destroyed crystal structure. It is found that after 10 hours of ball milling and 8 hours of sintering at 550 ℃, the synthesized sulfide solid electrolyte exhibits higher ionic conductivity, reaching 3.57×10^-3S/cm.

Lithium sulfide was prepared by solid phase syntheses, with lithium metal as the lithium source, sulfur powder as the sulfur source, and lithium nitride as the additive. Thermodynamic analysis results show that lithium nitride can promote the reaction of lithium metal with sulfur powder to synthesize lithium sulfide; Li₃N firstly reacts with sulfur powder to release N₂, leading to holes formed on the molten lithium metal sheet and the contact area between lithium metal and sulfur powder further expanded. Thus a loose and porous skeleton structure is formed, which is conducive to subsequent crushing and can reduce the risk of secondary reactions in the following ball milling process. With Li∶S∶Li₃N=2∶2∶0.4 (molar ratio), crude lithium sulfide can be obtained after 8 hours reaction at 100 ℃. It is then subjected to calcination, impurity removal and ball milling processes, and a kind of lithium sulfide products with purity greater than 99.95% and particle size less than 15 μm can be obtained, which can be used in EV. This method provides a new idea for industrial production of lithium sulfide products.

A single-factor experiment was conducted to explore the influence of rotation speed and lateral swing speed of polishing brush, and polishing current on the performance of copper foil and pinholes. Based on that, the polishing process was also optimized by applying response surface methodology, and thus the performance and apparent quality of copper foil was also improved. The results show that by using on-line polishing, with the rotation speed of the polishing brush at 450 r/min, the lateral swing speed of 350 r/min, and the polishing current of 0.50 A, the smooth surface (S surface) of the generated copper foil is uniform, and the pinhole defects are significantly reduced.

A kind of hydrogen storage alloy of La_0.7R_0.1Mg_0.2Ni_3.35Al_0.15 (R=La/Nd/Sm) was synthesized with induction melting method, and the effect of La substituted with rare earth element Nd/Sm on the phase structure, microstructure, and electrochemical performance of the hydrogen storage alloy was explored. The results show that the substitution of Nd or Sm for La doesn't change the phase composition of the hydrogen storage alloy, which is still composed of LaNi₅, (LaMg)₂Ni₇, and (LaMg)₅Ni₁₉ phases, but leads to higher abundance of LaNi₅ and (LaMg)₅Ni₁₉ phases, and lower abundance of (LaMg)₂Ni₇ phase in the hydrogen storage alloy. The hydrogen storage alloy, with La, Nd and Sm as R, deliver the maximum discharge capacities of 377 mAh/g, 382 mAh/g and 376 mAh/g, respectively, after the second charge-discharge cycle. With La substituted with Nd or Sm, the hydrogen storage alloy has its high-rate discharge capacity, the charge retention rate after 24 hours, and capacity retention rate after 100 cycles all improved to some extent, among which the hydrogen storage alloy with Nd as R is the best in all corresponding performance. Moreover, the substitution of La with Nd or Sm can make the hydrogen storage alloy with higher exchange current density and higher coefficient of hydrogen diffusion. Its high-rate discharge performance, exchange current density and hydrogen diffusion coefficient are all in in the same trend, indicating that high-rate discharge performance of the hydrogen storage depends on both exchange current density and hydrogen diffusion coefficient.

In order to improve the accuracy of the GRU neural network model in predicting the remaining useful life (RUL) of lithium-ion batteries, the GRU model was optimized based on PCA-GWO and then applied in the prediction. The results show that compared with the traditional GRU model, the PCA-GWO-GRU model presents higher prediction accuracy. When the starting point of the prediction is 90% of the original data, the prediction accuracy can reach the highest, with the corresponding RMSE of 0.004 9, MAE of 0.003 6, and R² of 0.986 3.

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.

Cathode and anode materials in spent lithium iron phosphate battery powder are difficult to be separated by flotation. In order to solve this problem, it was proposed that lithium iron phosphate battery powder was pretreated by oxidative roasting, and then subjected to a flotation process for seperation between the cathode and anode materials of lithium iron phosphate. The results show that after lithium iron phosphate battery powder is pretreated by oxidative roasting at 500 ℃ for 30 minutes, the subsequent flotation process can lead to the graphite-based anode material with carbon grade up from 47.63% to 97.70%, and the cathode material with carbon grade down from 24.00% to 1.01%, presenting a significant separation effect. In comparison, the battery powder without pretreatment has cobweb-like long carbon-chain organic matter on its surface, which causes adhesion between cathode and anode materials of batteries, resulting in poor separation effect by flotation. The pretreatment of oxidative roasting can effectively eliminate the long carbon-chain organic matter on those cathode and anode materials, thus enhancing the difference in surface properties between cathode and anode materials. As a result, the enhanced flotation separation effect makes graphite-based anode material recycled from spent lithium iron phosphate batteries.

In order to recover metal elements from the cathode materials of spent Li-ion batteries in an environmentally friendly and efficient way, three deep eutectic solvents (DES) were synthesized with choline chloride as hydrogen bond acceptor, malonic acid, succinic acid and adipate respectively as hydrogen bond donors. Then, Co and Li in the cathode materials of spent Li-ion batteries were leached by adopting these three DESs respectively. The effects of leaching time, liquid-solid ratio and reaction temperature on the leaching rates of Co and Li were explored, and the leaching residues were also characterized in terms of morphology and phase. The leaching mechanism was analyzed by FT-IR spectrum and UV-Vis absorption spectrum. It is shown that the leaching efficiency of metal elements can be enhanced by prolonging leaching time, increasing liquid-solid ratio and temperature. It is found that under the optimal conditions, including leaching time of 300 minutes, liquid-solid ratio of 100 mL/g, and temperature of 110 ℃, malonic acid-based DES, among those three kinds of DESs, can bring better leaching effect, with leaching rates of Co and Li all exceeding 99%. During the leaching of lithium cobalt oxide with those three DESs, Co exists in the form of bivalent in the leaching solution, and the coordination compound is in a tetrahedral structure.

With the calcium-magnesium slag generated in recycling process of spent Li-ion batteries as raw material, battery-grade lithium carbonate was prepared by adopting a process consisting of leaching for decomposition, purification, lithium precipitation and carbonization for decomposition. The results show that with the addition of MgSO₄·7H₂O at 1.1 times of the theory amount, initial pH of 1.5, reaction time of 2.0 h, solid-liquid ratio of 1∶6, reaction temperature of 90 ℃, and final pH of 3.5, the leaching rate of Li can reach 98.39% and the mass concentration of Li in the lixivium is 18.03 g/L. Then, the obtained lixivium is subjected to processes of defluorination with resin, impurity removal with NaOH, and Na₂CO₃ precipitation, and crude lithium carbonate can be obtained with purity of 95.11%. By adopting a process consisting of carbonization, removal of calcium and magnesium with resin, and pyrolysis, a battery-grade lithium carbonate with purity of 99.64% can be prepared. It is shown that by using this processing technique, the lithium recovery rate can reach 95.08%, presenting good prospect in industrial application.

A review of comprehensive recycling technologies for graphite anodes in spent lithium-ion batteries is presented, including hydrometallurgical process, a combination of pyrometallurgical and hydrometallurgical process, as well as mechanical recycling. And then, an in-depth analysis of advantages and disadvantages of each technology is also presented. It is particularly pointed out that there are various recycling technologies, but the development of an efficient and environmentally-friendly closed-circuit recycling process still faces challenges. The recycling approaches of graphite anodes in spent lithium-ion batteries are discussed in details, such as usage as anodes of rechargeable batteries, or for preparation of graphene. The research direction in the future is also forecasted aiming to provide theoretical and technical support for reutilization of graphite anodes in spent lithium-ion batteries with high-value added. It is suggested that research should focus on developing a simple, efficient and clean closed-circuit recycling processes to improve the recovery rate and purity of graphite anode materials while reducing environmental pollution. The research hotspots in the future should include lattice reconstruction and repairing technologies for graphite anode materials, as well as exploration of new applications of graphite anode materials in the fields of energy storage materials, catalysts, adsorbents among others.

In the flotation process of electrode materials from spent LiFePO₄ batteries, the occurrence of entrainment and entrapment usually leads to poor separation effect. Aiming at such problem, selective flocculation with polyvinylpiroxanone (PVP) and polyacrylic acid (PAA) was adopted to enhance the flotation effect in an experimental study, and the interaction mechanism between PVP and PAA and electrode materials was also analyzed. Results show that the firstly added PVP can be selectively adsorbed on the graphite surface by hydrogen bonding, thus inhibiting the spontaneous hydrophobic flocculation of graphite. Then, due to site-blocking effect, the subsequently-added PAA is inhibited to be adsorbed on the graphite surface, leading to selective flocculation of LiFePO₄ by PAA. A combined usage of PVP and PAA can not only make graphite effectively dispersed, but also lead to apparent particle size (D₅₀) of LiFePO₄ cathode material increased from 15.01 μm to 26.17 μm. As a result, the loss of LiFePO₄ due to entrainment in the flotation process of mixed electrode can be effectively reduced, thus the recovery rate of LiFePO₄ cathode material by flotation process can be improved from 71.41% to 83.59%.

Ball milling was adopted to assist leaching of valuable metals from the cathode powder of spent batteries in citric acid and hydrogen peroxide system. It is found that ball milling can exert mechanical energy on the reaction solution, leading to changes in its structure and physical and chemical properties. As a result, chemical reactions can occur, which not only increases reaction rate, but also shortens leaching time. It is shown that after 30 min leaching at 60 ℃, with citric acid concentration of 0.8 mol/L, H₂O₂ at a mass fraction of 20%, liquid-solid ratio of 6∶1, and rotation speed of 60 r/min for a ball mill, the leaching rates of lithium, nickel, cobalt and manganese can reach 99.6%, 99.5%, 99.3% and 98.5% respectively. It is concluded that this processing technique, being characterized by low cost and high efficiency, can provide a certain reference for recycling of spent batteries.

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.

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.

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.

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.

Based on the combination of the hunger games search (HGS) algorithm and the artificial neural network (ANN), a new hybrid model of HGS-ANN was developed to predict blasting vibration. Four different prediction models were established based on group method of data handling (GMDH), support vector machines (SVM), ANN and Sadov's empirical formula, and compared with HGS-ANN model in evaluating the performance of models. For this purpose, 32 sets of blasting data of an open-pit mine were collected.7 independent variables, including detonation distance, maximum single-stage charge, total charge, burden, hole spacing, number of holes and hole depth were selected as inputs, while the particle vibration velocity was selected as the output. With the root-mean-square error (RMSE) and the decisive factor (R²) as the evaluating indicators, the established models was compared in terms of their performances. The results show that the HGS-ANN model, with the RMSE and R² of 0.833 and 0.963, respectively, has performance better than the other four models. It is proposed that the HGS-ANN model can be used as an auxiliary tool to optimize the blasting design for reducing the blasting-induced seismic effect.

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.

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).

A flotation experiment was conducted for a low-grade fine-grained cassiterite from Yunnan. The median dosage of reagent was determined by a single-factor test, and then the reagent dosage for rougher flotation process of cassiterite was optimized by response surface methodology as follows: 285 g/t of activator (KT-51), 13 g/t of inhibitor (OL-1C) and 873 g/t of compound collector (YK-Sn+SN-705). A verification test on flotation with the addition of those agents yielded a tin rougher concentrate grading 1.460% Sn at 74.44% recovery, which was close to the results predicted by response surface methodology. In order to further explore the effect, a closed-circuit test was conducted, resulting in the tin concentrate grading 5.45% Sn at 66.70% recovery. It is shown that efficient recovery of low-grade cassiterite resources can be actualized.

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 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.

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 mineral processing test was conducted to treat a low-grade rubidium-bearing lepidolite ore from Hunan Province with the grade of Li₂O and Rb₂O respectively at 0.27% and 0.17%. A flowsheet including a desulphurization and a lithium flotation was adopted, and an efficient collector CK was used in combination with dodecylamine to collect lithium minerals under weak alkaline conditions. In a closed-circuit test, a lithium concentrate was produced with Li₂O grade and recovery of 2.71% and 86.34%, Rb₂O grade and recovery of 1.02% and 51.24%, respectively. It is concluded that efficient utilization of low-grade lepidolite ore can be actualized.

A mineral processing test was conducted to treat a lithium-tantalum-niobium-beryllium polymetallic ore with a lithium grade of 0.68% from Xinjiang. According to the process mineralogy study, this ore has spodumene as the dominant lithium minerals, and has low content of tantalum-niobium minerals. A flowsheet including a magnetic separation and gravity separation to recover tantalum-niobium minerals, and a flotation to collect lithium minerals can produce a tantalum-niobium concentrate with Ta₂O₅ grade and recovery of 17.110% and 41.69%, Nb₂O₅ grade and recovery of 19.670% and 42.63%, respectively, and a lithium concentrate with Li₂O grade and recovery of 5.12% and 75.21%, respectively.

To recover the copper resource therein, mineral processing of a slag-beneficiated copper sulfide ore from Congo (Kinshasa) with 9.62% Cu was investigated. A regrinding and reseparation flotation process was proposed based on multi-element chemical analysis and mineral occurrence analysis. It is found that with this process, a copper concentrates with Cu grade of 25.16% and Cu recovery of 90.67% can be collected.

In order to optimize the particle shape and gradation of machine-made sand, a vertical bar stirring mill was adopted for shaping tests. The effects of medium type, medium ratio, mill rotation speed and material/ball ratio on the particle shape of machine-made sand were investigated. The gradation and shape characteristics of unshaped and shaped sands were comparatively analyzed by using optical microscopy and image processing software. The results show that the shaping effect of zirconia medium is better than that of steel or alumina medium. With the zirconia balls with diameter of 6 mm and 8 mm in a mass ratio of 1∶1, rotation speed of 300 r/min, feed/ball mass ratio of 1∶3 and pulp volume fraction of 62.5%, the milling process results in the shaped sand with fineness of+0.15 mm 84.98% and flake granule accounting for 4.5%. The shaped machine-made sand has better compactness and angular characteristics, and it is qualified as the type I sand according to the standard GB/T 14684—2022, with better gradation and particle shape compared to the unshaped sand. The contour shape and angular characteristics of coarse granules can be greatly optimized than those of fine particles. It is concluded that under suitable conditions, a vertical bar stirring mill can obviously improve the shape of machine-made sand and optimize coarser grain composition.

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.

In order to identify the feasibility of preparing alkaline pellets with low-quality magnesium-containing flux, experiments on pelletizing, preheating and roasting were carried out. Three kinds of magnesium-containing flux from Wulongquan Mine of WISCO Resources Group Co., Ltd., including interbedded dolomite, light-burnt material and lightburnt dolomite, were taken for pelletizing, and then effects of different magnesia flux and the adding amount on pelleting, as well as following preheating and roasting processes of alkaline pellet were all explored. The results show that the green ball prepared with the flux of interbedded dolomite presents superior performance. It is found that with alkalinity of 0.8, the green ball prepared with two different blending schemes have drop number of 4.1 and 6.6 respectively from height of 0.5 m, and compressive strength of 20.3 N/pellet and 22.3 N/pellet respectively. By increasing the addition of magnesia flux in two blending schemes, both preheated balls and roasted balls have their strength decreased after an initial improvement. With alkalinity between 0.6 and 0.8, the prepared pellet can have compressive strength of 2 620 N/pellet and 2 963 N/pellet respectively after preheating and roasting process. It is recommended that with interbedded dolomite and light-burnt material as magnesia flux, the alkaline magnesium-containing pellet prepared with alkalinity of 0.6-0.8 can meet industrial requirements.

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.

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.

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.

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.

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.

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.