With bamboo as a raw material, different hard carbon materials were prepared by different impurity removal processes, and the effects of those processes on the impurity content, physical structure and sodium storage performance of hard carbon were explored. The results show that after impurity removal treatment, the bamboo-derived hard carbon has reduced impurity content and specific surface area, and increased interlayer spacing. With the preparation cost and the sodium storage performance of hard carbon comprehensively taken into consideration, acid leaching is chosen as the impurity removal process for hard carbon. It is shown that at a current density of 30 mA/g, the anode material with prepared hard carbon can have an initial Coulombic efficiency of 83.87% and a reversible specific capacity of 308.96 mAh/g; it demonstrates a capacity retention rate of 96.57% after 100 cycles at a current density of 300 mA/g, showing excellent sodium storage performance.

This paper presents the evolution path of intelligent technologies, from automated monitoring at early stage to modern AI-based decision support, and focuses on analysis of research results and application cases of key technologies, such as neural networks, the Internet of Things (IoT), digital twins and big data. It also presents discussion of the latest progress in application of a new generation of intelligent technologies represented by machine learning in safety management of non-coal mines. Specifically, technologies including deep neural networks, support vector machines, decision trees and random forests have shown advantages in aspects such as personnel safety management and positioning, monitoring and early warning of mine disasters, safe operation of mine equipment, and safety in mine blasting operation. Finally, the development trends of non-coal mine safety management are proposed, in terms of in-depth application and integration of intelligent technologies, compatibility of old equipment with modern intelligent technologies, and integrated management.

Aiming at the problems of high oxidation rate, high content of slime and high consumption of collector (butyl xanthate) for the copper-cobalt oxide ore from the Democratic Republic of the Congo, experimental researches were carried out with an auxiliary collector (MC-07) in its flotation process. The results show that at the stage of copper oxide ore flotation, with butyl xanthate as a single collector at a total dosage of 400 g/t, the concentrate is produced totally with a copper recovery of 78.41% and a cobalt recovery of 38.93%; while by using the conventional collector of butyl xanthate in combination with an auxiliary collector of MC-07, at the dosage of 99 g/t and 33 g/t respectively, the concentrate is finally produced totally with a copper recovery of 78.76% and a cobalt recovery of 39.30%. It is shown that small  additions of auxiliary collector of MC-07 can reduce the dosage of butyl xanthate with the similar technical indicators.

An experimental study was carried out on comprehensive recovery process for the gold-cobalt polymetallic copper ore in Bolivia. A flow sheet of Cu-preferential flotation followed by bulk Au-Co-Bi flotation was adopted, with OL-ⅡA as a Cu collector and OL-TL as a depressant. The Cu-preferential flotation process consisting of one stage of roughing, two cleaning and one scavenging produced a copper concentrate grading 30.00% Cu at 94.56% recovery, indicating separation between copper and arsenopyrite actualized by low-alkalinity flotation. Then, the obtained tailings were subjected to a bulk Au-Co-Bi flotation consisting of one stage of roughing, one cleaning and one scavenging, resulting in a Au-Co-Bi concentrate grading 19.50 g/t Au, 1.58% Co and 1.80% Bi, with corresponding recoveries of 92.22% Au, 96.33% Co and 58.87% Bi. It is concluded that the comprehensive recovery of metallic resources can be actualized from this gold-cobalt polymetallic ore.

In order to select an appropriate deep-sea polymetallic nodule collection method, a technical evaluation system was established based on five criteria, including green, economy, reliability, intelligence and safety (GERIS). Then, as for three kinds of collection methods, including collection with a rotary raking system, or a hydraulic collection system, and a robotic arm collection system, the weights of 22 engineering indicators were determined by adopting the Analytic Hierarchy Process (AHP), and also a quantitative comparison was made among those three typical methods. It is found that collection by a rotary raking system presents better performance in terms of collection efficiency, operation stability and safety, with a comprehensive score of 80.1, while the hydraulic collection system is characterized by simple structure and high efficiency, but is not environment-friendly and intelligent, with a score of 76.3. The robotic arm collection system shows some sort of potential in intelligent development, but is limited by its low efficiency and high mechanical complexity, with the lowest score of 70.2. Overall, the collection by a rotary raking system is more feasible in current engineering applications, and the hydraulic collection system may be banned to use due to strict environmental protection regulations, while the robotic arm collection system still has developmental potential for precise collection in high-value areas in the future.

The typical region of the Yuanma Basin (covering Mayang, Luxi and Yuanling counties) was taken in the research of landslide disaster. Based on the database of detailed survey of geological disasters from 2013 to 2022, landslide events with complete rainfall records were selected for research. Then, significant rainfall factors for landslide, including rainfall on the day of landslide occurrence and during those four days prior to it, and maximum rainfall rate on the occurrence day were selected out by adopting logistic regression analysis, and a logistic regression prediction model for rainfall-induced landslides in the Yuanma Basin was developed and validated by  studying representative landslide cases. The research results indicate that the rainfall-induced landslides in the Yuanma Basin is significantly correlated with rainfall on the occurrence day and during those 4 days prior to the occurrence. This confirms that the period including the occurrence day and those 4 days prior to the occurrence is critical for early warning of landslide in this region. A combined rainfall factors, consisting of R₀  (daily rainfall on the occurrence day), R₁ (rainfall of 1 day before occurrence), R₂  (rainfall of 2 days before occurrence) and R_h  (maximum rainfall rate on the occurrence day), present optimal significance in statistical analysis. The practical cases have validated that this logistic regression model constructed based on this factor combination has a prediction accuracy of 83%. It is concluded that this model can give a prediction with high precision and is of practical value.

In combination with experiments and multi-step finite element simulation, the residual stress distribution in components manufactured by laser powder bed fusion (LPBF) and the influence of the initial residual stress field on the laser shock peening (LSP)-induced compressive residual stress field. The validity of the simulation results was verified by the residual stress values measured with X-ray diffraction. The results show that the thermal stress of the lower and middle layer materials in the component fabricated by LPBF undergoes a transition from zero stress, compressive stress, tensile stress to compressive stress, while the top layer material shows a transition from zero stress, compressive stress to tensile stress, thus leading to tensile residual stress occurred on the surface layer of LPBF fabricated component, while compressive residual stress in the lower part. The action of initial residual stress field results in the reduced peak value but increased depth of LSP-induced compressive residual stress. The initial residual tensile stress field of LPBF components can exert a suppressive and dragging effect on the reverse plastic deformation caused by surface waves, leading to reduced intensity and changed position of the “residual stress hole”, which can improve the uniformity of LSP-induced residual stress distribution.

To explore the influence of land use change on landslide susceptibility, Liuyang City of Hunan Province was taken for research. An improved infinite slope model was established based on land use data from 2000 to 2020, by using an inversion model of root cohesion and dynamic hydrological correction, and the influence mechanism of land use change on landslide susceptibility was quantified. The model accuracy was verified by comparing six types of parameter combinations. It is found that the model considering spatial heterogeneity of root cohesion and saturated hydraulic conductivity corrected based on land use has extremely high prediction accuracy (AUC=0.8150), presenting a significant improvement compared with the traditional model. Besides, forest land conversion to land for construction significantly increases landslide susceptibility (with a frequency ratio of 1.4269), and decline of vegetation cover leads to reduction in root reinforcement.

To investigate the dynamic damage characteristics and energy evolution of sandstone in aquatic environments after engineering disturbance and blasting vibration, a split Hopkinson pressure bar (SHPB) was used to test three groups of saturated and dried sandstone with different initial damages. A statistical damage constitutive model was established by introducing initial damage and degree of saturation, which was then used in combination with damage curves to analyze the whole-process damage mechanism of sandstone with initial damage. It is found that the stress-strain curve of sandstone can be divided into four parts based on energy evolution. After reaching peak stress, things change. Elastic energy begins to release and a significant energy hysteresis phenomenon occurs throughout the failure process. At the same strain rate, the degree of fragmentation gradually increases as the initial damage becomes greater and sandstone is more saturated. The theoretical stress-strain curve of the modified damage constitutive model is in better coincidence with the practical one, presenting the highest correlation coefficient (0.991). The mechanism for whole-process sandstone damage can be characterized by the established damage curves. Furthermore, the initial damage and saturation-induced damage of sandstone are equivalent to its load-induced damage to a certain extent.

Extraction of rhenium from low-grade molybdenum concentrate by adopting a process of oxidative volatilization followed by ion exchange was explored in experiments. Firstly, a two-stage high-temperature oxidative roasting was adopted to oxidize rhenium into Re₂O₇. Rhenium and molybdenum were effectively separated due to rhenium volatilizing into the flue gas. The volatilization rate of rhenium reached 85.42% after roasting process at 675 ℃. Then, the rhenium-containing flue gas was eluted to get rhenium-containing solution, in which rhenium was selectively extracted with D201×7 ion exchange resin. With the solution pH of 9, liquid/solid ratio of 50 mL/g, a 20 min adsorption at temperature of 35 ℃ brought the adsorption rate of Re up to 97.52% and the adsorption rate of Mo less than 20%. Finally, a product of ammonium rhenate was prepared by stepwise desorption followed by concentration and crystallization. By this process, the total recovery of Re can reach 70.68%.

To explore the feasibility of using nano-ceramic balls in primary ball mill, a ball milling test was conducted on high-pressure roller mill product with steel balls and nano-ceramic balls as grinding media, and the particle size distribution characteristics and magnetic separation effect of the ground products were studied. The results indicate that with the feed materials singly in a size range of 2-3 mm or 1-2 mm, use of  nano-ceramic balls in combination with steel balls as the medium can reduce the overall grinding effect; while with the feed material singly in a size range of 0.6-1 mm, 0.3-0.6 mm, 0.15-0.3 mm or 0.074-0.15 mm, a combination of nano-ceramic balls and steel balls has a synergistic effect, which can enhance grinding performance; with the feed material singly in a size range of 0.3-0.6 mm, 0.15-0.3 mm or 0.074-0.15 mm, the mixed media with 50% steel balls can achieve the same grinding effect brought by the media with 80% steel balls; with the feed material in a size range of 0.074-0.15 mm, the combination of two balls brings the same grinding effect as the single use of steel balls; with the feed material in a size range less than 0.6 mm, the combination of two balls can bring grinding effect approximately equivalent to that by singly using steel balls. It is concluded that a combination of  nano-ceramic balls and steel balls can be used instead of single steel balls in the primary grinding of materials in size range less than 0.6 mm.

As for the high-calcium silver-vanadium ore from Yichang of Hubei Province, which has low grades of silver and vanadium but high content of calcium, the feasibility of removing calcium-bearing minerals therein, predominantly dolomite, by reverse flotation was explored through experiments, and the effects of grinding fineness, type and dosage of depressant, pH of pulp and collector dosage on decalcification and vanadium recovery were investigated. The results show that with grinding fineness of -0.074 mm 77.19%, sodium silicate, sodium oleate and sodium carbonate at dosage of 400 g/t, 800 g/t and 1500 g/t, respectively, a closed-circuit reverse flotation test can produce a vanadium concentrate grading 1.04% V₂O₅ at 93.56% recovery, with CaO content of 3.37%. It is shown that the calcium-bearing minerals have a CaO grade of 27.55%, showing CaO removal rate reaching 85.34%.

To rationally select parameters for pipeline transportation of ultra-fine tailings slurry, the influencing factors of pipeline resistance in transportation were classified based on theoretical analysis. Effects of different factors on resistance loss in ultra-fine tailings slurry pipeline were investigated by adopting response surface methodology (RSM), and the significance of each factor was obtained, for which engineering verification test was performed then. The results show that those three internal influencing factors, such as slurry concentration, slurry temperature and cement-sand ratio, are in descending order of sensitivity, and the interactions among them, including interaction between concentration and temperature of slurry, interaction between slurry concentration and cement-sand ratio, interaction between cement-sand ratio and slurry temperature, are also in descending order of sensitivity; while the external factors, such as pipe diameter, flow rate and stowing gradient, and their interaction, including interaction between pipe diameter and inlet flow rate, interaction between pipe diameter and stowing gradient, interaction between inlet flow rate and stowing gradient, are also in descending order of sensitivity. The factor optimization results indicate that with fixed external factors, the optimal combination of slurry properties are as follows: slurry concentration of 63.5%, cement-sand ratio of 1∶6, and slurry temperature of 51.5 ℃; while with fixed internal factors, the optimal combination of transportation parameters are as follows: pipe diameter of 270 mm, inlet flow rate of 1.63 m/s, and stowing gradient of 5. Based on verification test, it is found that the maximum calculation deviations of the confidence interval under the influences of internal and external factors are 10.82% and 3.41%, respectively.

To address high cost of smooth blasting using detonating cords for mine’s roadways, explosive train in blast hole with only one detonator was realized by taking advantage of sympathetic detonation (SD) of explosive. After performing experiments on SD with emulsion explosive in different charge diameters, with different charge weight and other constraint conditions, the SD distances under different conditions were obtained. The results show that SD distances of emulsion explosive with a charge diameter of 27 mm in a PVC tube and blast holes are 10 cm and 90 cm respectively, and constraint conditions have a significant impact on the SD distance of explosives. With the charge weight increasing from 150 g to 300 g, the SD distance is at least 5 cm longer, indicating the SD distance increases with the increase of charge weight. On the other hand, the charge diameter of emulsion explosive also exerts some impact on the SD distance. The SD distance of emulsion with a charge diameter of 35 mm in blast holes is 5 cm longer than that of the emulsion with charge diameter of 27 mm. Industrial experiments on blasting show that the roadway constructed by adopting sympathetic detonation can be well formed, which can not only meet requirements of the subsequent tunnelling in mine but also cutting blasting cost.

To improve the accuracy of fracture recognition in borehole images, a borehole fracture recognition approach for open-pit mine was proposed. First, borehole images of an open-pit mine is obtained with an intelligent borehole inspection camera, and then data augmentation is performed by using random cropping and image flipping, while median filtering is used for noise reduction and images are converted to grayscalere, so as to eliminate noise and reduce computational complexity. Next, spatial attention and channel attention mechanisms are integrated into the U-Net model to improve the semantic segmentation model for fractures, forming an AU-Net model, which can enhance the model′s ability to extract features from both overall and local image information. Experimental results show that compared to the original U-Net model, the AU-Net model can achieve lower loss and higher accuracy in the fracture recognition dataset by borehole imaging. Specifically, the mean intersection over union is improved by 4.38 percentage points, up to 82.34%, bringing better image segmentation effect.

In order to accurately know the progress in frontier technologies and research hotspots in environmental monitoring and protection during deep-sea mining, after the patents and academic literature from January 1, 2005 to April 14, 2025 in the filed of deep-sea mining were retrieved with IncoPat and Web of Science, a statistical analysis was performed with bibliometric methods for542 published patents and 469 academic literature, and then the development trend in this field was also discussed. It is shown that a synchronous increase in both patents and academic literature highlights the support of basic research for technological innovation. By formulating corresponding policies and through institutional collaboration, China hasshifted its place from following others to keeping pace and even leading the pack in theoretical research. China has also put emphasis on the technologies of environmental monitoring and protection in its scientific research on deep-sea mining, and established a technical system and theoretical framework with in situ observation technologies for environmental impacts during deep-sea mining at the core. As a result, the research perspective has shifted toward understanding of complex system mechanisms. In the future, the environmental monitoring and protection system for deep-sea mining will be composed of four core modules, including environmental monitoring, environmental assessment, environmental management and environmental protection, and form an ecological risk supervision and management framework through the whole mining process, which will also becontinuallyupdated.

Based on a triaxial creep test of saturated phyllite, a time-dependent variation law of creep characteristics of saturated phyllite under the coupling effect of pore water pressure and unloading stress was investigated. The results show that the creep failure of saturated phyllite is a typical brittle failure, characterized by instantaneous application of a force. An increase in unloading stress and pore water pressure can accelerate the creep failure of saturated phyllite. The Burgers model was improved by adopting a variable of instantaneous failure, and an elasto-plastic damage body was established by introducing a variable of time-dependent damage. With the improved Burgers model in serial connection with the elasto-plastic damage body, a three-dimensional damage constitutive model for rock creep was proposed in consideration of the coupling effect of excavation unloading and pore water pressure. After regression analysis and parameter identification with the Levenberg-Marquardt (L-M) algorithm for the test results, it is found that the theoretical stress-strain curve from the proposed model are in good coincidence (R²>0.9) with the practical ones for decay, steady-state and acceleration phases of saturated phyllite from the experiments, verifying the accuracy of the model. It is concluded that this model can effectively describe the creep behaviour of mine slope mass under the long-term coupling effect of excavation unloading and pore water pressure.

After an introduction of the current status of gallium resources and analysis of the occurrence state of gallium in sodium aluminate solution, zinc smelting slag, tailings from vanadium extraction and coal-based solid waste, progress in the research of gallium extraction processes is elaborated and the adaptability, advantages and disadvantages of each technique are also summarized. Finally, based on the discussion of problems faced by the gallium industry and the development direction in the future, it is suggested that iteration and upgrading of gallium extraction processes should be vigorously promoted based on China’s scale advantage in alumina industry.

Effects of roasting temperature and heating rate on the crystalline form evolution of calcium arsenate during heat treatment were investigated. The heat-treated calcium arsenate was leached by strong acids (sulfuric acid, nitric acid, hydrochloric acid, aqua regia), and the relationship between the crystalline form of calcium arsenate and arsenic concentration in leaching solution was investigated. The results show that calcium arsenate undergoes significant crystalline form transition during roasting process, and higher roasting temperature can result in higher degree of crystallization. The heat-treated calcium arsenate is leached with acids and it is shown that less arsenic is leached out as the roasting temperature rises. After calcium arsenate is subjected to roasting at 500 ℃, the concentration of arsenic in the leaching solution can meet GB 5085.3—2007. After calcium arsenate is subjected to a roasting process at 900 ℃ and above, the concentration of arsenic in the leaching solution satisfied GB 3838—2002.

An intermittent sedimentation test was performed for vanadium-titanium magnetite tailings to obtain settling curves of flocculated tailings, and then the solid flux in sedimentation by flocculation was calculated by Coe-Clevenger equation and material balance calculation. An innovative Φ38 m heavy-duty and efficient thickener is designed to have a unit area processing capacity of 1000 kg/(m²·h). The industrial application of this thickener in dewatering of vanadium-titanium magnetic tailings show that with dry ore processing capacity of 1100 t/h and the feed concentration of 20%－25%, its underflow has concentration of 45% and the overflow has solid content less than 200 mg/L. It is concluded that such thickener can solve the technical problems in the production faced by enterprises, and also bring enterprises enhanced economic and environmental benefits.

A new short-process preparation technique for battery-grade iron phosphate was explored with iron powder and phosphoric acid as main raw materials. The effects of iron powder dissolution mechanism, iron phosphate reaction conditions, and mother liquor recycle on product indicators were investigated. The results show that the dissolution rate of iron powder can reach 97.92% at a temperature of 70 ℃, with phosphoric acid at a concentration of 20%, iron and phosphorus at a ratio of 1/3, and iron powder at a size of 150 μm; after 1 h  precipitation at 100 ℃, with an addition of hydrogen peroxide at 110% of the theoretical amount, an iron phosphate with D₅₀ of 2 μm was prepared with the precipitation rate of 98.86%. The obtained iron phosphate has stable crystal form with uniform crystal grains, and the contents of elemental impurities are significantly lower than the requirements specified in the HG/T 4701—2021 standard. The precipitated mother liquor in the process can be recycled, leading to actualization of  low-carbon and green production.

With nickel laterite ore from Morowali of Indonesia as the raw material, effects of various factors, including reaction time and temperature, stirring speed, acid-to-ore ratio, and slurry concentration, on the leaching rate were systematically investigated. Additionally, the leaching mechanism was explored by using the PHREEQC, a thermodynamic calculation software. The results show that after one hour reaction at 250 ℃, with acid-to-ore ratio of 300 kg/t and slurry concentration of 25%, the leaching rates of Ni and Co can reach 98.40% and 99.90%, respectively, while the leaching rates of Fe and Al are just 3.84% and 40.25%, respectively. The high selectivity of high pressure acid leaching (HPAL) is attributed by the factor that at high temperatures, not only the hydrolysis reaction of Fe and Al can be promoted, but also the pOH can be decreased from 14 to 10,  which thereby inhibits leaching of Fe and Al. As the temperature rises to above 200 ℃, the number of H+ increases, which can ensure a sufficient amount of H+ for leaching of nickel and cobalt metals.

The mechanical properties and energy evolution law of dolomite under a combined action of dry-wet cycle and cyclic loading and unloading were explored. The results show that the structural damage caused by dry-wet cycles leads to the transformation of dolomite from brittle fracture to ductile fracture, which is manifested by an increase in the area of hysteresis loops and a decrease in peak strength. At the early stage of cyclic loading and unloading, a strengthening effect is observed, and then the dolomite develops into the strain-softening and damage stages. An energy analysis indicates that the total input energy is mainly stored in the form of elastic strain energy, and the proportion of dissipated energy increases slowly with the accumulation of damage. Additionally, based on the variation of the damage variable defined by dissipated energy, the damage evolution tends to be stable after a progressive and accelerated process.

Iron phosphate dihydrate (FePO₄·2H₂O) is usually synthesized via three technical routes, including ammonium process, sodium process and iron process. A systematical evaluation of its thermodynamic properties  is presented, which  can reveal the phase transition behavior of iron phosphate dihydrate during the dehydration process, and provide a theoretical basis for selection of technical route for industrial synthesis. The enthalpy change (ΔH), entropy change (ΔS), Gibbs free energy change(ΔG), and logarithm of the reaction equilibrium constant (lgK) of the core reaction of those three processes are calculated by using HSC Chemistry 6.0 software, and the thermodynamic data of dehydration process are verified by performing a thermogravimetry-differential scanning calorimetry (TG-DSC) experiment. The results show that the synthesis by sodium process has the lowest ΔG and the highest lgK, indicating its thermodynamic spontaneity and reaction rate are optimum, followed by the ammonium process, while the iron process presents the worst performance. The TG-DSC experiment results show that the dehydration process of iron phosphate dihydrate is exothermic at 709.9 ℃, corresponding to the transformation of FePO₄ from α-quartz phase to β-quartz phase. Featuring high spontaneity and rapid reaction, the sodium process is considered as a industrial synthesis with thermodynamic advantage.

To reveal the relationship among uniaxial compressive strength, tensile strength and shear strength, 159 sets of rock mechanics data collected from 38 mines were taken as samples. Firstly, the relationship between uniaxial compressive strength and tensile strength was characterized by data analysis, and the range of uniaxial compressive and tensile strength in the formulae for calculating shear strength was calibrated. Then, a BP neural network prediction model was constructed, with which the shear strength of rocks can be predicted with uniaxial compressive strength and tensile strength as the input layer. The results show that: the uniaxial compressive strength of rock is 7.6-27.8 times tensile strength; the cohesion value obtained from multiple comparison tests is 1.0-2.2 times that from the original empirical formula, and the tangent value of internal friction angle is 0.35-1.00 times that from the original empirical formula, presenting high confident and reliable results;  based on comparison between the predicted value with BP neural network and the actual value,  the cohesion deviation ranges from -10.53 MPa to 20.12 MPa, and the internal friction angle deviation ranges from -18.43° to 28.97°, exhibiting an overall normal distribution.

To meet the requirements during a 2-year transition period from open-pit to underground mining in Miaochong Iron Mine, its productivity continuity and mining stability were analyzed. Based on ore reserve estimation, Panel ① and Panel ② at the southern end of the roadway at midsection (370 m) of ore body are decided to be an initial mining plan for the transition period. Then, a model including ore bodies, rock formation, open-pit mine and underground roadways is built with FLAC3D software, which is then adopted to analyze the displacement, stress and plastic zone distribution characteristics of the open-pit and roadways at the midsection (370 m) during the transition period. The results show that the ore quantities in Panel ① and Panel ② at the  midsection (370 m)  during the transition period can ensure production capacity requirement, but also is sufficient for subsequent mining. It is found that the overall displacement of the open-pit and roadways at the midsection (370 m) is less than 5 mm, and compressive stress becomes dominant in the stress distribution, which is far lower than the stress resistance of the rock mass. There is no large-scale continuous plastic zone, indicating good stability and small impact by mining disturbance. In practical production, it is recommended that a segmented millisecond blasting should be adopted to achieve a staggered blasting operation  between open-pit and underground mine. Besides, efforts should be intensified in monitoring open-pit slope and underground roadways to ensure safe production during the transition from open-pit to underground mining.

Effects of quenching and tempering at different temperatures on the microstructure and hardness of annealed W6Mo5Cr4V2 steel were studied by means of OM, SEM, XRD analysis and hardness test. The results show that the microstructure of quenched W6Mo5Cr4V2 steel is mainly composed of martensite, MC carbide rich in V, W and Mo, and M₆C carbide rich in W and Mo, as well as residual austenite. As tempering temperature rises, the carbide in the microstructure of W6Mo5Cr4V2 steel grows in size, and the hardness decreases after an initial increase. After quenching at 1160 ℃plus three times of tempering at 540 ℃, W6Mo5Cr4V2 steel has its carbide become smaller and evenly distributed, and its residual austenite almost eliminated, showing the hardness up to 64.2HRC.

With the dust from a tin smelter as raw material, the occurrence state of tin (Sn) and indium (In) therein was firstly studied. Then, a combined processing technique consisting of water leaching and oxidative acid leaching was adopted to separate and recover the key elements of Sn, In, Zn and Cd from the tin smelting dust, and effects of factors including suluric acid concentration, liquid-solid ratio, reaction temperature and reaction time on the leaching process were explored. The results show that Sn and In in the tin smelting dust mainly exist in the forms of SnO₂, In₂S₃ and Zn₂SnO₄. After water leaching treatment, the dust was leached with sulfuric acid at a concentration of 200 g/L by adding potassium permanganate at a dosage of 1.5%, with liquid-solid ratio of 5.0, at a temperature of 65 ℃ for 120 min, resulting in the leaching rates of In, Zn and Cd at 82.00%, 95.60% and 94.30% respectively, while the leaching rate of Sn at 0.84%. After such treatment, the Sn content in the dust increased from 42.44% to 60.87% with an enrichment ratio of 1.43. The particles of the acid leaching residue were porous on the surface, showing that the dust with dense structure changed to the residue with loose one. This tin-rich acid leaching residue with low impurity content can be back to tin smelting process, and indium can go to the subsequent process for extraction and recovery. By this way, efficient recovery and utilization of valuable metals from tin smelting dust can be actualized.

The polymetallic ore from Shizhuyuan of Hunan Province was taken for research. Based on the characteristics of uneven coarse-fine dissemination of minerals and insufficient deliberation of Mo-Bi sulfide ore for flotation, an enhanced recovery technology by stepwise separation was developed for the low-grade Mo-Bi sulfide ore. The results show that an experiment by adopting such stepwise separation technique produced a bulk flotation concentrate grading 1.31% Mo and 2.83% Bi at corresponding recoveries of 88.43% and 85.99%, presenting 5.34 and 4.80 percentage points up, respectively, compared to on-site conventional bulk flotation process. This creates favorable conditions for the following tungsten flotation from the bulk flotation tailings. It is shown that a closed-circuit tungsten flotation can produce a tungsten concentrate grading 44.64% WO₃ at 84.12% recovery.

There are well-developed faults in an open-pit molybdenum mine, which may lead to slope instability during open-pit mining. Three typical faults running through the ultimate boundary were selected to investigate progressive instability mechanism of the slopes in the open-pit mine under coupling effect of multiple faults by integrating Rhino+Griddle 3D geological modeling and FLAC^3D multi-field coupling simulation. Furthermore, the safety factors of slopes under different working conditions were calculated, and relatively unstable slopes were also identified for addressing the subsequent safety of the ultimate boundary. The simulation results show that, plastic failure and tensile stress concentration will occur in the slope at the junction of Zone C and Zone D, while local plastic failure will occur in the faults, which, however, won’t induce instability failure in the surrounding slopes; there won’t be much displacement in the slope at the ultimate boundary, with the maximum displacement (2.44 cm) at the toe of slope; the safety factors of the ultimate boundary of open pit under natural working conditions and rainfall are 2.48 and 2.36 respectively, indicating that the slope is stable. However, slope at Zone E with F1 fault is considered to be with a relatively instability, for which comprehensive measures including real-time monitoring, prevention and reinforcement can be taken to ensure the safety.

A high-pressure grinding roll (HPGR) was adopted for dry milling of the weakly magnetic iron ore from Jingtieshan prior to magnetizing roasting. The results indicate that compared to wet milling, the dry milling process can reduce production costs and energy consumption. The extrusion pressure of the HPGR exerts a direct impact on the shape of the obtained cake and the subsequent breaking process. In contrast to single extrusion, multiple extrusions lead to a significant reduction in power consumption of the main machine. With the pressure of 4 MPa, the final powder with approximately 53% of passing size of -0.074 mm will require the main machine with power consumption of 6.74 kWh/t, and a circulating load of about 330%. It can meet the requirement of particle size for the subsequent roasting process.

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.

To precisely regulate the performance of site mixed emulsion explosive (SMEE), influences of key parameters, including aqueous phase (ammonium nitrate/water), oil phase (diesel oil/engine oil), shear rate and proportion of sensitizer, on the performance of SMEE were systematically investigated. A quantitative correlation model describing the variation of charge density and detonation velocity with various factors were established by means of multiple linear regression and path analysis. The results show that moderately increasing content of ammonium nitrate or reducing water content can significantly improve the detonation velocity; increasing the proportion of engine oil in the oil phase or reducing the proportion of diesel oil can enhance the energy output of explosive. A higher shear rate can reduce the internal phase particle size of emulsion, thereby increasing detonation velocity; however, a larger proportion of sensitizer can lead to a decrease in detonation velocity. Path analysis results indicate that priority should be given to the proportion of sensitizer and content of ammonium nitrate in regulation of detonation velocity of emulsion explosive, while both the proportion of sensitizer and shear rate should be taken into consideration in adjusting charge density.

In order to improve recoveries of rare earth resources, Bayan Obo rare earth ore was taken for research, for which a combined process consisting of XRF sorting, low-intensity magnetic separation (LIMS) and flotation was adopted to recover rare earth elements (REEs) and iron minerals therein. With appropriate parameters, a rough concentrate of rare earth was obtained with a REE grade of 9.44%, recovery of 94.03% and an enrichment ratio of 1.48, and the tailings for discarding had a REE grade of 1.03%, presenting a discarding rate of 5.97%. After that, a process consisting of LIMS and flotation was adopted, producing a rare earth concentrate grading 61.23% REE at 79.81% recovery, with a yield of 19.89%, and the tailings with iron grade of 58.68% at 83.27% recovery. It is concluded that such processing technique can improve the REE grade of the feed into the mill and also simplify the flotation flowchart, providing a new idea for efficient recovery of rare earth ore.

Based on the causes of historical dam failure accidents in tailings ponds, a safety grade evaluation index system was built for tailings ponds. The correlation between safety evaluation indexes was demonstrated with Pearson correlation analysis method. An in-depth analysis was conducted for the distribution of sample data to confirm that the sample data met the requirements of the Kriging method for data distribution. Then, the weight of each safety evaluation index was calculated with entropy weight method. The two safety evaluation indexes with higher sensitivity were selected as the X-axis and Y-axis of the Kriging geostatistical model. A geostatistical model was established by using the Kriging method and was verified with empirical case data. The results show that the predicted safety grades of 12 groups of tailings pond data with known safety grades in the geostatistical model are completely consistent with the actual safety grades, which verifies the feasibility and high accuracy of this method.

The fundamental principles of stereolithography (SLA), digital light processing (DLP), and two-photon polymerization (TPP) in photo-curing technique for ceramic were reviewed. Based on systematical introduction and analysis of the research status, application fields of SLA, DLP, and TPP technologies, as well as the existing challenges, a comprehensive review was provided of ceramic slurries and their performance optimization, photo-curing mechanisms, and subsequent debinding and sintering processes. Finally, prospects for obtaining ceramic slurries with high performance, finished products with superior mechanical properties and translating research outcomes into practical applications were discussed. Furthermore, several recommendations were proposed, including increasing the types of ceramic slurries, accelerating the development of composite ceramic materials, and making more efforts in research of large-size ceramic components.

Several pieces of hard paper with different numbers, dip angles and widths were embedded into specimens to simulate structure of closed joint in rock masses and prepare rock mass models with different joints. Effect of joints on blast-induced failure characteristics of rock mass was analyzed with a high-speed camera and a 3D laser scanner, so as to explore the rules of crack propagation and fragment size distribution during rock blast. It is found that joints can disperse blasting energy and hinder crack penetration, leading to a decrease in the average size of blast-induced fragments as the number of joints increases. Wider joints can make diffraction and reflection of stress waves much more complicated, intensify energy dissipation, and also hinder crack propagation; while joints with small width are prone to make blast-induced fragments smaller in size. The interaction between joint dip angle and the propagation direction of the blast stress wave can significantly affect the crack propagation mode, and excessively large dip angles can easily hinder stress wave propagation.

An improved algorithm combining Rapidly-Exploring Random Trees (RRT) and Artificial Potential Field (APF) was proposed for obtaining an overall path planning for deep-sea collector vehicles. Based on the kinematic model of the collector vehicle, the RRT sampling mechanism was optimized by a target-biased strategy, and an adaptive repulsive coefficient was introduced to improve the potential field function, thereby enhancing obstacle avoidance and target reachability.Verification was carried out by simulation under two different working conditions. The results show that in Condition 1 (complex environment), the RRT*-APF algorithm has its searching time shortened by 73.1%, the number of expanded nodes reduced by 50.7%, and the path length shortened from 1542.35 m to 1486.16 m compared to the RRT* algorithm, being more suitable for complex environments. In Condition 2 (simple environment), the RRT-APF algorithm has its searching time shortened by 67.4%, the number of expanded nodes reduced by 52.6%, and the path length shortened from 973.58 m to 910.27 m compared to the traditional RRT algorithm, being more suitable for simple environments.

A refractory ore characterized by ultra-fine gold particles disseminated therein was taken for flotation test. A technique of re-grinding and re-flotation of the middlings, together with the self-developed collector of ZHS-3, was adopted to enhance the collection of fine-grained gold, resulting in a gold concentrate grading 43.70 g/t Au at 74.29% recovery, and a secondary concentrate grading 15.60 g/t Au at 4.28% recovery. Two obtained products had a total gold grade of 39.79 g/t and recovery of 78.57%. It is shown that both gold grade and recovery are improved compared with conventional flotation processes. This processing technique can achieve efficient recovery of fine-grained gold, thus improving resource utilization.

In Meishan Iron Mine, the iron concentrate produced on the site has SiO₂ grade more than 6.0%. Aiming at this problem, an experimental study was carried out based on the microscopic identification of different concentrate products by using a new process flow, in which the magnetic field intensity of low-intensity magnetic separation (LIMS) was reduced for roughing, and a process of regrinding and re-separation was added for the scavenging concentrate by high-intensity magnetic separation (HIMS). The effects of those technical transformation on the TFe grade of iron concentrate and the content of impurity SiO₂ therein were explored. The results show that after such technical transformation, the LIMS can produce a concentrate grading 63.57% TFe and 3.37% SiO₂ with corresponding recoveries of 72.79% and 12.94%, with a yield of 52.21%; while the HIMS can produce a concentrate grading 44.79% TFe and 9.07% SiO₂ with corresponding recoveries of 17.20% and 11.67%, with a yield of 17.51%. This new flowchart can produce the concentrate grading 58.85% TFe and 4.80% SiO₂ at corresponding recoveries of 89.98% and 24.61%, with a total yield of 69.72%. It is shown the SiO₂ content in the total concentrate of Meishan Mine can be greatly reduced.