25 August 2026, Volume 46 Issue 4
    

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    MINING
  • Optimization of Bench Height for Open-Pit Mines Under Freeze-Thaw Cycles in High-Altitude Cold Regions
    NIE Gang, XU Hai, JIANG Yucun, MA Chi
    Mining and Metallurgical Engineering. 2026, 46(4): 1-7. https://doi.org/10.3969/j.issn.0253-6099.2026.04.001
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Aiming at optimization of bench height for open-pit mines in high-altitude cold regions, a multi-objective decision-making method considering the influence of freeze-thaw cycles was proposed. Based on parameters including shoveling equipment selection and toe burden, the bench height was preliminarily determined to be within the range of 12-18 m, and seven alternative schemes were proposed. Numerical simulation of slope stability after 25 freeze-thaw cycles was conducted by adopting GeoStudio software, and the safety factors of each scheme ranged from 1.196 to 1.214. Models for ore dilution and loss, drilling and blasting cost, and ore-rock transportation work were then established to calculate the performance values of each scheme in terms of dilution rate, loss rate, drilling cost, blast cost, and transportation work. On this basis, the entropy-weight method was used to determine the weight of each index, and the comprehensive scores of alternative schemes were calculated. The results show that the 15 m bench scheme achieves the highest comprehensive score (0.5166), and is identified as the optimal solution. Incorporating the mechanical effects of freeze-thaw cycles into the multi-objective evaluation framework, this method provides a quantitative decision-making basis for bench height design of open-pit mines in high-altitude cold regions.
  • ProbabilityStatisticsBased Safety Control of Blast Vibration for ShallowBuried Underground SoftRock Engineering
    LI Chaopeng, HUANG Haixian, LI Haiqian, LI Xiaoliang, YE Qipeng, LU Haiyong, LI Qiyue
    Mining and Metallurgical Engineering. 2026, 46(4): 8-15. https://doi.org/10.3969/j.issn.0253-6099.2026.04.002
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    As for underground engineering projects in shallowburied soft rock, extensive blast vibration monitoring was carried out along the axial direction on the tunnel ground surface. Based on the monitoring data, probability distribution analysis confirmed that the peak particle velocity (PPV) followed the lognormal distribution. Considering the randomness of PPV, the lognormal distribution theory and confidenclevel analysis method were introduced. A blast vibration safety prediction and control model was established by combining the PPV attenuation model with the probability distribution function, and then applied to the sensitive sections of the project. The results show that in a blasting scheme with the maximum charge per delay at 43.2 kg, the horizontal distance between sensitive point 2# and the blast source should be greater than 35.044 m to satisfy the safety criterion of a 95% confidence; while in a scheme with the maximum charge per delay at 18.6 kg, that horizontal distance shall exceed 25.660 m to meet the 95% confidence. On the basis of this model, differentiated blasting control schemes are formulated for sensitive tunnel sections. This proposed method provides theoretical support for blasting operation for similar underground softrock projects.
  • Particle Flow Simulation of Splitting Mechanical Properties of Rock with Cross-Cracks at Different Angles
    HE Changyao, CHEN Junzhi, REN Chunfang
    Mining and Metallurgical Engineering. 2026, 46(4): 16-26. https://doi.org/10.3969/j.issn.0253-6099.2026.04.003
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To understand the splitting-tensile behavior of internal cross-cracks in rock, discrete element splitting simulation tests were carried out by using a particle flow code (PFC2D) based on the physical and mechanical parameters of rock obtained from laboratory tests. The results show that the tensile strength of specimens with pre-fabricated cracks is lower than that of intact specimens. When the angle between the main crack and the loading direction ranges from 0° to 60°, the peak strength of specimens decreases with the increase of the secondary crack angle; when the angle ranges from 60° to 90°, the peak strength increases with the increase of the secondary crack angle. In general, the tensile strength of specimens follows the rule that the larger the angle difference between the main and secondary cracks, the smaller the tensile strength. Under splitting loading, pre-fabricated cracks do not change the loading mode of specimens but only reduce their bearing strength. Micro-cracks in cross-crack specimens are dominated by tensile micro-cracks, which initiate near the tips of pre-fabricated cracks, propagate toward the loading ends and coalesce with increasing load, resulting in specimen failure. Irreversible transformation of internal energy occurs during rock failure. When the loading reaches the storage limit of elastic strain energy, the elastic strain energy is rapidly converted into dissipated energy for micro-crack initiation and propagation as well as particle movement. A large number of acoustic emission events occur simultaneously, and the number of micro-crack increases exponentially.
  • Noise Reduction Method and Time-Frequency Characteristics of Blasting Vibration Signals for High Slopes
    REN Lilin, HUANG Yu, CAO Qingbin, HE Li, QI Gangxian, ZHAO Yongming, CAI Lujun, ZHONG Dongwang, LI Linna
    Mining and Metallurgical Engineering. 2026, 46(4): 27-35. https://doi.org/10.3969/j.issn.0253-6099.2026.04.004
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    When drilling and blasting are adopted for excavation of high slopes, blasting-induced vibration signals are susceptible to noise interference and their effective features are difficult to extract accurately, a noise reduction method based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) combined with wavelet threshold is proposed. Blasting vibration signals are reprocessed based on mean ratio (MR), sample entropy, and correlation coefficient. The proposed method is verified by simulated and field measured blasting vibration signals. The simulation results show that the signal-to-noise ratio (SNR) of the proposed method reaches 27.80 dB and the root-mean-square error (RMSE) is 0.2091, presenting a superior noise-reduction performance compared to the other four methods. Engineering application results indicate that this proposed method can effectively suppress high-frequency noise and improve the resolution and stability of time-frequency analysis for blasting vibration signals. Further analysis reveals that the dominant frequency of blasting vibration signals is mainly within the range of 10－60 Hz with energy concentrated within 16－125 Hz; the dominant frequency of rockfall impact signals is mostly in the range of 40－720 Hz with more complex spectral structures, and its energy is mainly distributed in 62－1000 Hz.
  • A Credibility Evaluation Method for Rock Mass Quality Classification Integrating Multi-source Information
    XU Jing, JIANG Chengyu, ZHAO Zi’an, CHEN Shenglun, ZHANG Liming, WANG Chen, JI Jianhua
    Mining and Metallurgical Engineering. 2026, 46(4): 36-45. https://doi.org/10.3969/j.issn.0253-6099.2026.04.005
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    Aiming at the inconsistency of grading results and difficulty in determining credibility for rock mass quality classification methods such as the RMR method, Q-system method and BQ method, a credibility evaluation method for rock mass quality classification based on analytic hierarchy process (AHP), fuzzy comprehensive evaluation (FCE) and D-S evidence theory is proposed. Firstly, the evaluation vector of rock mass quality grade is obtained via the AHP-FCE model. The evaluation vectors obtained by the three classification methods are taken as independent bodies of evidence. The D-S evidence theory and credibility weighting model are introduced to fuse and revise multi-source evidence, so as to obtain an optimal rock mass quality classification result integrating multi-source information. On this basis, a calculation platform for the credibility of rock mass quality classification is established with MATLAB GUIDE. Verification with 16 groups of measured data from No.2 Ping’an Phosphate Mine shows that the evaluation results obtained by the proposed method are more consistent with engineering practice than those from any single classification method. After revision by the credibility weighting model, the conflict coefficients of 16 groups of original evidence decrease from 0.60-0.82 to less than 0.01. The conflict problem of multi-source evidence is effectively solved, and the credibility of rock mass quality classification results is improved.
  • Creep Characteristics and Nonlinear Creep Model of Soft Rock in Open-Pit Slopes
    WEI Zhonggen
    Mining and Metallurgical Engineering. 2026, 46(4): 46-53. https://doi.org/10.3969/j.issn.0253-6099.2026.04.006
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    With the slopes of an open-pit mine in Inner Mongolia as the research background, the creep characteristics of soft rock in the slopes were investigated by means of field monitoring, laboratory test and theoretical analysis. Real-time monitoring results of the slopes from radar and GNSS found that the creep deformation is relatively larger on the eastern side of the northern slope, which requires key protection. When the axial stress exceeds the long-term strength, the soft rock goes through four deformation stages: instantaneous deformation, decelerating creep, steady-state creep and accelerated creep. Creep deformation and creep rate of soft rock are positively correlated with axial stress. A nonlinear creep model for slope soft rock is established by combining elastic elements, fractional-order element and nonlinear viscoplastic body (NVPB). This model can well describe the whole creep process of slope soft rock, with higher fitting accuracy than that of traditional Burgers model, and also demonstrate favorable applicability.
  • Dynamic Mechanical Response and Microstructure Evolution of Mudstone in Tailings Reservoir Slope
    LIU Ping, ZHANG Junfeng
    Mining and Metallurgical Engineering. 2026, 46(4): 54-59. https://doi.org/10.3969/j.issn.0253-6099.2026.04.007
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    To reveal the damage and degradation mechanisms of mudstone in tailings reservoir slopes under complex environmental conditions, dynamic uniaxial compression tests, CT scanning, and scanning electron microscopy (SEM) were conducted to analyze the evolution of dynamic uniaxial compressive strength and structural damage mechanisms of mudstone under three typical environmental conditions, i.e., wet-dry cycles, freeze-thaw cycles, as well as wet-dry and freeze-thaw cycles. The results show that the dynamic compressive strength and dynamic elastic modulus of strongly weathered mudstone continuously decay with the increase of cycle number, and the deterioration rate gradually stabilizes after 80 cycles. Among those three environmental damage conditions, the coupling effect of wet-dry and freeze-thaw cycles brings the most significant deterioration to mudstone. After 100 wet-dry and freeze-thaw cycles, the dynamic compressive strength and dynamic elastic modulus of mudstone decrease, and the connectivity of pore networks increases remarkably, presenting a strong linear relationship (negative correlation) between porosity and dynamic compressive strength. Complex environments can reduce the effective bearing area and stress transfer efficiency of rock mass by accelerating pore expansion and crack propagation, thus eventually lead to structural damage and strength deterioration of mudstone. Relevant suggestions for slope reinforcement engineering of tailings reservoirs are finally put forward based on the research results.
  • Evolution Law of Surface Rock Movement and Systematic Analysis of Shaft Stability for Mining of Super-Large Area in Deep Super-Large Mine
    SHI Lei, YU Zhenjian, WANG Yuding, GONG Yongchao, LIN Weixing, XU Min, LU Jintao, LI Wei, ZHANG Qingsong, ZHOU Yuxin
    Mining and Metallurgical Engineering. 2026, 46(4): 60-66. https://doi.org/10.3969/j.issn.0253-6099.2026.04.008
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    With a domestic super-large iron mine taken as research background, FLAC3D was adopted to calculate and analyze the rock movement law by mining and backfilling operations of underground super-large area, and the deformation degrees of the ground surface and shafts were also evaluated according to relevant standards. It is found that the hanging wall and foot wall in the mining disturbed zone are concentrated within rock movement zones. The peak displacements of subsidence and uplift are approximately 9 cm and 6 cm respectively, which decrease gradually in an arch-shaped pattern toward the ground surface or deep footwall strata. Meanwhile, deep mining activities tend to aggravate the deformation of rock masses in middle sections. The maximum absolute values of surface inclination, curvature and horizontal deformation are 0.22 mm/m, 0.002×10-3/m and 0.12 mm/m, respectively, all less than the maximum allowable deformation values specified in relevant standards. It indicates that deep mining is unlikely to induce tilting deformation of surface buildings (structures), whereas the southern and northern service shafts are located within the movement zones. Further shaft stability analysis reveals that the southern and northern service shafts are subjected to mining disturbances, and the peak values of inclination, curvature and horizontal deformation of shaft wall are 0.52 mm/m, 0.09×10-3/m and 0.18 mm/m respectively, which are also within the permissible limits according to relevant standards. The maximum cumulative subsidence over time at each monitoring point of the main and auxiliary shafts to the surface is less than 4.6 mm, which indicates that the underground mining of super-large area exerts slight influences on the stability of the main and auxiliary shafts, as well as other buildings (structures).
  • Burn Cut Design with Ultra-Deep Central Hole for Fractured Surrounding Rock
    LUO Jia, ZHANG Hao, GAO Pengfei
    Mining and Metallurgical Engineering. 2026, 46(4): 67-73. https://doi.org/10.3969/j.issn.0253-6099.2026.04.009
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    Aiming at the problems of low blasthole utilization rate, high specific explosive consumption, high detonator consumption, and irregular roadway forming during the excavation of roadways with fractured surrounding rock in a gold mine, an optimization method for burn cut parameters by adopting ultra-deep central hole is proposed. The optimized rock-breaking mechanism is revealed by triple synergistic effect, including enhanced rock throwing via central hole charging, stress wave guidance through large empty-hole spacing, and bottom pre-fragmentation. A three-dimensional cut blasting model is established using ANSYS/LS-DYNA software to simulate four working conditions featuring a 200 mm ultra-deep central hole and enhanced bottom charge, with empty-hole spacings of 130 mm, 160 mm, 190 mm, and 220 mm. By analyzing the effective stress distribution, cut-cavity dimensions, rock-throwing process, and energy variation under different working conditions, the optimal empty-hole spacing is finally determined to be 160 mm. Field test results show that the optimized blasting scheme increases the blasthole utilization rate from 87% to 95.8%－97.8%, reduces explosive consumption by 13.3% and detonator consumption by 14.29%, and controls the over-excavation of two roadway sidewalls within 100 mm. Such findings can provide a theoretical basis and technical reference for similar roadway excavation engineering in fractured surrounding rock.
  • Shear Mechanical Properties and Fracture Mechanism of Sandstone Containing Intersecting Fractures
    MA Erhui, YU Zhen, YE Hongtao, ZHANG Rongzhou, ZHUANG Xianpeng
    Mining and Metallurgical Engineering. 2026, 46(4): 74-80. https://doi.org/10.3969/j.issn.0253-6099.2026.04.010
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    The shear mechanical behavior of red sandstone specimens with prefabricated V-shaped fractures was systematically investigated via laboratory shear tests and numerical simulations, from the perspectives of strength parameters, crack-initiation locations, coalescence modes and stress-field evolution. The results show that the deterioration of internal friction angle and cohesion of specimens is the most significant when the crack opening angle α = 110° and azimuth angle β = 0°. The finally formed fracture surfaces with coalescence in specimens are parallel to the shear direction, whereas the crack-initiation locations are strongly controlled by the azimuth angle β. The stress-field distribution shows clear zoning behavior: the low-stress zone presents an inclined S shape, while high-stress and shear-stress zones concentrate at fracture tips and end boundaries. From the mesoscopic perspective, principal stresses dominate the development of wing fractures, and the coupled compression-shear effect is the fundamental cause for the generation of secondary fractures.
    • EXPLOITATION OF DEEP SEA MINERAL RESOURCES
  • Analysis of Influencing Factors for Polymetallic Nodules Collection Efficiency of a Wall-Attached Jet Collector Head
    ZHENG Tao, JIN Guoqing, ZOU Li, YU Zongbing , LIN Qingyuan
    Mining and Metallurgical Engineering. 2026, 46(4): 81-88. https://doi.org/10.3969/j.issn.0253-6099.2026.04.011
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    In consideration of uneven distribution of seabed nodules and continuous travel of a collector vehicle during deep-sea mining operations, a CFD-DEM coupling approach was used to investigate the effects of particle abundance, traveling speed, and their combined actions on the collection efficiency of a wall-attached jet collector head and particle transport behavior. The results show that under static conditions, when particle abundance increases, more nodule particles enter the effective zone of the wall-attached jet, and collection efficiency rises accordingly. Nevertheless, excessively high particle abundance can lead to massive accumulation of particles in front of the pick-up mechanism, inhibiting continuous particle transport and lowering collection efficiency. It is found that the preferable particle abundance is 12.60 kg/m2. Under dynamic working conditions, collection efficiency also exhibits a trend of initial increase followed by a decrease with increasing traveling speed. At too low traveling speed, particle supply cannot remain continuous, while at excessively high speed, the effective interaction time between particles and collector head is reduced. Both scenarios are unfavorable for stable particle transport. And collection performance is satisfactory with the traveling speed at 0.15-0.20 m/s. It is concluded that the particle transport near the pick-up mechanism is jointly governed by particle abundance and traveling speed. Higher collection efficiency depends on the appropriate balance among particle supply, effective interaction time and transport capacity of the pick-up mechanism.
  • Effect of Particle Settling Characteristics on Plume Diffusion in Density-Stratified Environments
    ZHANG Li, ZHANG Yan, ZHANG Yinrui, ZHANG Xuhui, LU Xiaobing
    Mining and Metallurgical Engineering. 2026, 46(4): 89-96. https://doi.org/10.3969/j.issn.0253-6099.2026.04.012
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    To explore the lateral diffusion law of particle plumes resulting from a midwater discharge of sediment during deep-sea mining, effects of terminal velocity of settling particles and seawater-buoyancy-flux ratio of discharged fluid on plume diffusion process in density-stratified environments was studied by adopting large-eddy simulation. The numerical model was validated based on water-tank test, and it is found that the average relative error of the lateral diffusion radius for single-phase plumes is 2.94%, and the average error for particle plumes at stable stage is 5.3%. The results show that particle settling decreases the residual buoyancy of plume and diffusion layer moves upward. The lateral diffusion radius tends to stabilize after an initial increase with the growth of terminal settling velocity, and the corresponding dimensionless parameter at the critical terminal settling velocity is ws/Us≈0.1. The lateral diffusion radius reaches its minimum value when the density of discharged fluid is close to that of ambient seawater (P≈0). This study provides theoretical support for quantitatively optimizing parameters and controlling environmental impact of tailings discharge during deepsea mining operation.
  • Flow Characteristics of Seabed Sediments Under Continuous Disturbance by Multiple Grousers
    CHEN Zihui, OU Yujia, HU Qiong
    Mining and Metallurgical Engineering. 2026, 46(4): 97-104. https://doi.org/10.3969/j.issn.0253-6099.2026.04.013
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    To investigate the flow characteristics of sediments disturbed by the track of a collector vehicle during deep-sea mining, numerical simulations of continuous sediment disturbance by multiple grousers were conducted based on the Eulerian multiphase flow model. The mass and the dispersion velocity of disturbed sediments were analyzed, and the effects of in-situ disturbance, subsidence depth, and bottom-current velocity on the flow characteristics of sediments. The results indicate that when a collector vehicle travels 1.5 meters at a speed of 0.6 m/s, the mass of disturbed sediments at the water-sediment interface reaches 70.8 kg. After 2.5 seconds, the horizontal dispersion velocity of the plume reaches 0.37 m/s and the vertical dispersion velocity is 0.269 m/s. Subsidence depth increases, the dispersion intensity aggregates. In-situ disturbance causes more severe damage to the soil layer. Seabed bottom-current velocity, although being lower, can also bring influence to both the concentration and dispersion range of sediments.
    • MINERAL PROCESSING
  • Dynamic Characteristics of Materials and Separation Performance Prediction During Dry Magnetic Separation
    SONG Yongzhe, ZENG Shanglin, ZHANG Shengguang, LI Ra
    Mining and Metallurgical Engineering. 2026, 46(4): 105-109. https://doi.org/10.3969/j.issn.0253-6099.2026.04.14
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    The force acting on material particles in a dry magnetic separator was systematically investigated. It is found that the motion trajectory of particles during the separation is determined by the combined effects of material magnetic permeability, drum rotation speed of magnetic separator and magnetic field intensity. With a certain dry magnetic separator as an example, the dynamic separation process of materials during magnetic separation was calculated, and then verified by performing a test on dry magnetic separation of ilmenite. The results show that the average deviation between the predicted trajectory and the actual trajectory of simulated particles is within 8%. It is concluded that the dynamic simulation method can satisfactorily predict the motion trajectory of liberated magnetic minerals.
  • Experimental Study on Combined Collector for Improving Flotation Recovery of Low-Grade Scheelite Ore from Henan
    ZHANG Gaojie, YU Xinyang
    Mining and Metallurgical Engineering. 2026, 46(4): 110-115. https://doi.org/10.3969/j.issn.0253-6099.2026.04.015
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    To improve low-temperature flotation behavior of the refractory low-grade scheelite ores from Henan, a combined collector HQ-3 (95%FX-6 + 5%PEG-2000) was developed to enhance the low-temperature flotation separation between scheelite and calcium-containing gangue minerals, and then flotation tests were conducted to determine reagent regime suitable for such scheelite. On that basis, a closed-circuit flotation test by adopting a flowchart consisting of low-temperature roughing and high-temperature cleaning was performed at a temperature ranging from 5 ℃ to 10 ℃, with 1800 g/t of sodium carbonate as the regulator, 750 g/t of water glass as the depressant and 260 g/t of HQ-3 as the collector in the roughing stage. As a result, a scheelite concentrate grading 28.06% WO3 was obtained at 85.15% recovery. It is shown that compared with FX-6, the combined collector HQ-3 can improve the recovery of WO3 from the roughing stage at a low temperature by 10.89 percentage points.
  • Experimental Study on Enhanced Recovery of Associated Silver from Lead Concentrate in an Overseas Lead-Zinc Ore
    LIU Zhongrong, ZHAO Junfeng, XIAO Jinxiong, ZHOU Yufeng
    Mining and Metallurgical Engineering. 2026, 46(4): 116-119. https://doi.org/10.3969/j.issn.0253-6099.2026.04.016
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    To improve the recovery of associated precious metal Ag from an overseas lead-zinc ore, mineral processing tests were carried out based on raw ore process mineralogy. The results show that silver mainly occurs as exposed silver sulfide and encapsulated silver in sulfides. A process consisting of decarbonization and lime-free lead flotation was adopted, with aniline dithiophosphate as a collector, and zinc depressant CB-1 and auxiliary zinc depressant W-1 added in the roughing of lead flotation. As a result, a lead concentrate grading 56.70% Pb, 8.93% Zn and 1432.30 g/t Ag was obtained, with corresponding recoveries of 80.73%, 2.13% and 59.07%, respectively. It is concluded that compared with the original lime-based process, the recoveries of Pb and Ag can be increased by 2.80 and 4.83 percentage points respectively, while in the lead concentrate, Zn grade can be decreased by 1.30 percentage points and Ag grade up by 35.80 g/t.
  • Enhanced Flotation of High-Silicon Bauxite with Combined Collectors and Surfactants and Its Mechanism
    GUO Jidong, ZHAI Yiqing, TUO Biyang, ZHENG Ping, LI Shuanglang, WANG Zhijie
    Mining and Metallurgical Engineering. 2026, 46(4): 120-126. https://doi.org/10.3969/j.issn.0253-6099.2026.04.017
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    To realize quality improvement and desiliconization of high-silicon bauxite, binary and ternary collectors were prepared with sodium oleate as the main component, compounded with benzohydroxamic acid, sodium dodecyl sulfonate, sodium dodecyl sulfate and n-octanol, respectively. The effects of single collector, binary collector and ternary collector on the flotation of high-silicon bauxite were systematically investigated. The interaction mechanisms between diaspore and kaolinite in bauxite and the collectors were revealed via contact angle measurement, zeta potential test, Fourier transform infrared spectroscopy and reagent adsorption capacity analysis. The results indicate that flotation performance of binary collectors is obvious superior to that of single collector. Flotation with sodium oleate combined with benzohydroxamic acid at a total dosage of 800 g/t can produce the concentrate with an Al2O3 grade of 56.49% at a recovery of 64.85% and an alumina-to-silica ratio of 2.96. While with a ternary collector composed of sodium oleate, benzohydroxamic acid and sodium dodecyl sulfonate at a total dosage of 1200 g/t, the flotation can yield the concentrate with an Al2O3 grade of 61.17% at a recovery of 79.84% and an alumina-to-silica ratio of 3.80. The contact angle, zeta potential, infrared spectroscopy and adsorption capacity results demonstrate that both the binary collector and the ternary collector interact more strongly with diaspore than with kaolinite, suggesting that the collectors possess better selective collection of diaspore.
  • Enrichment of Platinum-Group Metals in a Certain Tailings
    SU Xiaohui, XU Weiguang, LI Wenjuan, LU Bingang, LUO Chunhua, WANG Miao, DAI Qihang, SONG Yongsheng, WEN Jiankang, ZHOU Huying
    Mining and Metallurgical Engineering. 2026, 46(4): 127-130. https://doi.org/10.3969/j.issn.0253-6099.2026.04.018
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    Platinum group metals (PGMs) occurs as associated elements in Jinchuan copper-nickel ores and are always recovered together with copper and nickel by flotation. Nevertheless, substantial amounts of PGMs are still lost into tailings, leading to tailings containing 0.07 g/t Pt, 0.06 g/t Pd, alongside 0.0745 g/t Au and 5.54 g/t Ag. It is found that platinum and palladium mainly exist in the forms of michenerite, merenskyite, and Pd- and Pt-bearing bismuthotelluride minerals, finely disseminated and mostly encapsulated by silicate gangue, valleriite, pyrrhotite and other minerals. With those features taken into consideration, experimental investigations on PGM enrichment were carried out by multi-cycle gravity concentration with fabric-lined sluice. The results show that after five cycles of gravity concentration via fabric-lined sluice followed by grinding and re-concentration, the final tailings are obtained with the grades of Pt and Au decreased to 0.02 g/t and 0.05 g/t at recoveries of 74.48% and 53.04%, respectively. A combined separation process consisting of gravity concentration with fabric-lined sluice, shaking table concentration and low-intensity magnetic separation can lead to Pd primarily enriched into magnetic products, while Pt and Au concentrated in shaking table concentrates. This provides a feasible technical idea and research direction for the efficient recovery and utilization of PGMs in this type of tailings.
  • Experimental Study on Comprehensive Recovery of a Complex Refractory Copper-Cobalt Oxide Ore from DRC
    DU Changzhen, HE Guichun, MENG Qingbo, XU Xiaoping, XU Xiaoyi, YU Lihong
    Mining and Metallurgical Engineering. 2026, 46(4): 131-135. https://doi.org/10.3969/j.issn.0253-6099.2026.04.019
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    A comprehensive recovery test was conducted for a complex refractory copper-cobalt oxide ore from the Democratic Republic of the Congo (DRC). A combined process of copper flotation for enrichment followed by high-intensity magnetic separation (HIMS) for cobalt recovery was adopted. Sodium sulfide was used as activator, butyl xanthate as primary collector, TP as auxiliary collector, and No.2 oil as frother. In a closed-circuit test, a flotation process consisting of two-stage roughing, two-stage scavenging, and two-stage cleaning was adopted to preferentially recover copper, and the flotation tailings were then treated by HIMS to recover weakly magnetic cobalt-bearing minerals. Finally, the closed-circuit test produced a copper concentrate grading 16.31% Cu and 0.24% Co with recoveries of 80.82% Cu and 29.41% Co and a cobalt concentrate grading 0.304% Co at 40.34% recovery. It is concluded that this combined process can enhance the floatability of pseudomalachite and chrysocolla through a synergistic effect of sulfide activation and auxiliary collectors, and can also actualize effective recovery of cobalt minerals by HIMS. Accordingly, the overall recovery of copper and cobalt can be significantly enhanced.
  • Recycle Water Treatment for Mineral Processing of Yuanjiacun Iron Mine
    SHEN Ping, WEI Yufeng, LI Rongchao
    Mining and Metallurgical Engineering. 2026, 46(4): 136-139. https://doi.org/10.3969/j.issn.0253-6099.2026.04.020
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    In Yuanjiacun iron mine, the mineral processing water is recycled and then reused in flotation and magnetic processing stage, resulting in dissatisfied processing indicators. To address this problem, simulated wastewater was used to investigate the corresponding treatment technology and the mineral processing performance of the treated wastewater. Based on the verification with the recycle water on site, it is found that polyacrylamide (PAM), blue liquor and Ca2+ are the primary water quality factors influencing separation performance, and sodium hypochlorite, potassium ferrate and sodium carbonate can be used respectively to treat the mineral processing water containing them. After treatment, the recycle water is returned to the concentrator, leading to the processing indicators comparable to those obtained with clean water. 
  • Comprehensive Recovery and Utilization of Molybdenum Tailings from a Concentrator in Jinduicheng
    DONG Suizhen, DU Fengmei
    Mining and Metallurgical Engineering. 2026, 46(4): 140-144. https://doi.org/10.3969/j.issn.0253-6099.2026.04.021
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    To comprehensively utilize molybdenum tailings, experimental researches were systematically carried out for the molybdenum tailings from a concentrator of Jinduicheng Molybdenum Mine. Based on process mineralogy study, valuable components in the tailings were determined to be stepped recovered by flotation. Firstly, by adopting kerosene combined with No.2 oil, a flotation process consisting of one roughing and two scavenging resulted in 21.23% Mo recovery to the concentrate grading 0.47% Mo, and tailings with Mo grade  of just 0.0087%. Secondly, a process of pre-desliming followed by flotation with TB-3 collector was applied to remove mica, resulting in the flotation tailings with significantly reduced mica content, which laid a foundation for subsequent separation. Finally, such flotation tailings were processed by adopting fluorine-free alkaline flotation for separating feldspar and quartz therein without regrinding. As a result, feldspar products with a yield of 29.23% and K2O and Na2O contents of 7.34% and 1.01%, respectively, and quartz products with a yield of 27.87% and SiO2 grade of 83.14% were successfully produced. It is shown that such molybdenum tailings exhibit great potential for comprehensive recovery. It is concluded that the proposed combined process flow consisting of re-flotation of molybdenum, mica removal, and separation of feldspar and quartz by fluorine-free alkaline flotation is technically feasible for simultaneous recovery of metallic and non-metallic resources.
  • Synthesis of 4-(Chloromethyl) Benzohydroxamic Acidand Its Flotation Performance for Wolframite
    HAN Lei, LUO Yunbo, CHEN Ruipeng, ZHANG Faming, XIE Zhenxuan
    Mining and Metallurgical Engineering. 2026, 46(4): 145-149. https://doi.org/10.3969/j.issn.0253-6099.2026.04.022
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    Conventional hydroxamic acid collectors suffer from weak collecting capacity and high dosage consumption. To address these drawbacks, 4-(chloromethyl) benzohydroxamic acid was synthesized, and its flotation performance for wolframite was systematically investigated. With methyl 4-(chloromethyl) benzoate, hydroxylamine hydrochloride and sodium hydroxide as raw materials, the optimal synthesis conditions were determined as follows: methyl 4-(chloromethyl) benzoate, hydroxylamine hydrochloride and sodium hydroxide in a molar ratio of 1∶1.2∶2.35, reaction temperature of 35 ℃, reaction time of 4 h, and pH of 5 at the terminal acidification. Tests on flotation of wolframite indicate that 4-(chloromethyl) benzohydroxamic acid outperforms benzohydroxamic acid in collecting ability. To achieve equivalent flotation indices, the required dosage of the synthesized reagent is lower than that of benzohydroxamic acid.
    • METALLURGY
  • Effects of Electrolyte Additives  Br- and I- on Electrochemical Properties of Aluminum-Air Battery Anode
    YU Hailin, LI Yifan, LI Hongbin, CHENG Hao, LI Xinyi, TIAN Zhongliang, PENG Ke
    Mining and Metallurgical Engineering. 2026, 46(4): 150-157. https://doi.org/10.3969/j.issn.0253-6099.2026.04.023
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    To improve the electrochemical performance of aluminum-air batteries, Br- and I-  with weak electronegativity were adopted to regulate the hydrogen-bond structure of electrolyte and modify the electrode-electrolyte interface, so as to suppress hydrogen evolution corrosion of aluminum anode. The results indicate that the introduction of Br- and I- into electrolyte can significantly reduce the hydrogen evolution rate and self-corrosion rate of aluminum anodes, and remarkably improve the electrochemical performance of both aluminum anodes and aluminum-air batteries. After adding 3 mol/L KBr and 5 mol/L KI into KOH electrolyte, the hydrogen evolution rate and self-corrosion rate of aluminum anodes decrease to 13.79 mL/(cm2·h) and 13.5 mg/(cm2·h), 9.54 mL/(cm2·h) and 11.5 mg/(cm2·h), respectively. The corresponding corrosion inhibition efficiencies are 42.4% and 50.9%. Furthermore, the discharge specific capacities of the aluminum-air batteries can reach 1167.1 mAh/g and 1674.4 mAh/g at 25 mA/cm2.
  • Technology for Pellet Quality Improvement Based on Intensive Mixing of Iron Concentrates
    YU Ying, LI Shaochun, DU Yanqing, JI Zhiyun, FAN Xiaohui, SHI Jianjun, GAN Min, WANG Xiaolong, LIU Yi, WENG Xingyang, PEI Naiyi
    Mining and Metallurgical Engineering. 2026, 46(4): 158-162. https://doi.org/10.3969/j.issn.0253-6099.2026.04.024
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Aiming at the differences in physic-chemical properties of various iron concentrates and the difficulty in fully eliminating raw-material fluctuation by conventional dry blending, a technique of wet mixing combined with intensive mixing was adopted, and its effect on mixture homogeneity and pellet properties were investigated. The results show that wet mixing for 3 min can greatly improve the homogeneity of TFe, FeO and －0.074 mm fraction content in the mixed iron concentrates. After 3 min wet mixing and 40 s intensive mixing, the mixture has each homogeneity index basically equivalent to that after 60 s independent intensive mixing. The obtained green pellets have the compressive strength and drop strength improved by 12.17% and 13.95%, respectively, and preheated pellets and fired pellets have the compressive strength up by 7.64% and 10.63%, respectively, compared to that after raw material is just processed with 40 s intensified mixing without wet mixing. Meanwhile, the fluctuations in various pellet properties are remarkably reduced. It is concluded that this process can improve the homogeneity of various iron concentrates at the source and shorten the intensive mixing time, which provides technical support for quality improvement and stable operation in pelletization.
  • Catalytic Pyrolysis of Ammonium Sulfate Wastewater via CuO-Based Chemical Looping for Resource Recovery of Ammonia and Sulfur
    YUAN Zhiye, MA Weilou, CHEN Juexi, YI Yuxin, CHEN Chuye, CHEN Zhaoru, YANG Lishan
    Mining and Metallurgical Engineering. 2026, 46(4): 163-168. https://doi.org/10.3969/j.issn.0253-6099.2026.04.025
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    Aiming at the bottleneck that NH3 and SO2 generated during ammonium sulfate pyrolysis tend to spontaneously recombine and are difficult to be separated efficiently, an integrated process consisting of crystallization, pyrolysis and recycling, with CuO as the oxygen carrier in chemical looping was proposed. Experimental results indicate that the ammonia release rate exceeds 96% at the ammonia releasing stage after reaction at 400 ℃, with ammonium sulfate and copper oxide in a molar ratio of 1∶1.5. While at the sulfur releasing stage, after 90 min reaction at 750 ℃, sulfur release rate is over 98%. It is found that after five cycles of CuO-based chemical looping pyrolysis, both the ammonia-release and sulfur-release rates remain higher than 95%, and CuO also can be regenerated via air calcination. This process provides a feasible technical route for resource utilization of nitrogen-containing wastewater.
  • Determination Method of Calcium Fluoride Content in Complex Low-Grade Fluorite Ore
    ZHOU Ting, LI Zishang, YANG Binghong, YANG Lin
    Mining and Metallurgical Engineering. 2026, 46(4): 169-174. https://doi.org/10.3969/j.issn.0253-6099.2026.04.026
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    An optimized two-step separation-titration method was adopted to determine calcium fluoride content in a complex low-grade fluorite ore. Firstly, the sample was leached with 2% dilute hydrochloric acid for 150 min under magnetic stirring to efficiently separate interfering minerals such as calcite, dolomite and apatite, showing the leaching rates exceeding 98%. The residue was further leached with 80 g/L aluminum trichloride solution, and the calcium fluoride content was subsequently quantified via EDTA titration. Given that approximately 10% of fluorite would be leached by 2% hydrochloric acid, a correction coefficient (K=1.10) was introduced to calibrate the test results. The experimental results demonstrate that the relative errors for samples with various calcium fluoride contents determined by this method are within the permissible range (±0.25%), showing excellent consistency with theoretical blending values. The determination results are basically consistent with data obtained by Mineral Liberation Analyzer (MLA) and total fluorine content testing. It is concluded that this method effectively addresses the difficulty in accurate determination of calcium fluoride in complex low-grade fluorite ore, and can provide a reliable reference for mineral resource evaluation and optimization of beneficiation and metallurgical processes.
  • Resource Utilization of Copper Smelting Slag: Blending Optimization and Sintering Behavior Regulation
    YU Xiaolyu, LIANG Yanhui, GAO Feng, LI An, XU Yanwei, LIU Weiwei
    Mining and Metallurgical Engineering. 2026, 46(4): 175-182. https://doi.org/10.3969/j.issn.0253-6099.2026.04.027
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    To optimize the blending of copper slag and copper concentrate in copper smelting process, thermodynamic analysis, phase-diagram calculation and experimental research were combined to systematically investigate the effects of blending ratio on phase evolution, sintering characteristics and sulfur separation behavior. The results show that an increase in the copper slag ratio from 40% to 60% leads to a remarkable rise in the fraction of oxide phases and a drop in the fraction of sulfide phases in the system, as well as higher liquid-phase-forming capacity. The structure of the sintered product gradually changes from loose and porous to dense and continuous, and reaches its most stable state when the copper slag ratio ranges from 50% to 60%. A higher copper slag ratio facilitates the formation of Fe-Ca-Si composite oxides, which greatly enhances the structural stability of sintered products. With a rise in oxygen concentration from 40% to 60%, sulfur volatilization capacity is substantially improved, and the sulfur volatilization efficiency rises by 11 percentage points.
  • Experimental Study on Synergistic Leaching of Lithium and Aluminum from Coal Ash by Ammonium Sulfate Roasting - Water Leachin
    XU Shixiong, WU Lin, ZHONG Fangjun, LI Xi, REN Ping, LUO Xingfa, CHENG Jiangguo, DONG Lei, WU Jing
    Mining and Metallurgical Engineering. 2026, 46(4): 183-189. https://doi.org/10.3969/j.issn.0253-6099.2026.04.028
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    Ammonium sulfate roasting - water leaching process was adopted to synergistically leach lithium and aluminum from coal ash, and the effects of mass ratio of ammonium sulfate to fly ash, roasting temperature, roasting time, liquid-to-solid ratio, leaching temperature and leaching time on leaching rates of lithium and aluminum were also investigated. The results show that under the optimized conditions: ammonium sulfate and fly ash in a mass ratio of 4∶1, roasting temperature of 400 ℃, roasting time of 2 h, liquid-to-solid ratio of 4∶1, leaching temperature of 80 ℃ and leaching time of 30 min, the leaching rates of lithium and aluminum reach 86.77% and 78.04%, respectively. Mechanism analysis indicates that mullite, the host phase of lithium, reacts with ammonium bisulfate (the thermal decomposition product of ammonium sulfate) at 400 ℃ to generate soluble ammonium aluminum sulfate and aluminum sulfate, resulting in destruction of mullite crystal structure. After being released, lithium reacts with ammonium bisulfate to form lithium sulfate, which enters the aqueous phase during water leaching, thus realizing efficient synergistic leaching of lithium and aluminum.
  • A Precursor Particle Detection Method Based on Improved Mask R-CNN
    WU Zijian, XIAO Jingfeng, ZHUO Xiaojun, HUANG Yong, XIA Xing
    Mining and Metallurgical Engineering. 2026, 46(4): 190-195. https://doi.org/10.3969/j.issn.0253-6099.2026.04.029
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    An improved Mask R-CNN based method for precursor particle detection is proposed. Multi-branch feature extraction is employed to capture particle features for feature fusion, and detection results of precursor particles are output through a dual-branch output module. The experimental results demonstrate that the proposed method achieves a detection accuracy of 93.2% for precursor particles, with an inference time of 15.1 ms per image. The model is characterized by both high accuracy and real-time inference efficiency, which can provide critical technical support for the production of highly-consistent precursor particles.  
  • Adsorption Performance of Modified UIO-66 for Lead, Zinc and Manganese Ions in Aqueous Solution
    CHEN Ning, ZHANG Hui, YANG Jinmei
    Mining and Metallurgical Engineering. 2026, 46(4): 196-202. https://doi.org/10.3969/j.issn.0253-6099.2026.04.030
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    Modified metal-organic framework (MOF), UIO-66-TFA, was synthesized via hydrothermal reaction of zirconium tetrachloride, with terephthalic acid as the ligand and trifluoroacetic acid as the modulator. The characterization results reveal that the as-prepared modified MOF exhibits highly dispersed and uniform nanostructure. With adsorption time of 50 min, initial solution pH of 8, and reaction temperature of 40 ℃, an addition of 0.5 mg/mL UIO-66-TFA can result in the adsorption capacities toward Pb2+, Zn2+ and Mn2+ reaching 693.5 mg/g, 419.9 mg/g and 367.1 mg/g, respectively in the aqueous solution. After five consecutive adsorption-desorption cycles, UIO-66-TFA can still retain more than 88% of its initial adsorption capacity for Pb2+, Zn2+ and Mn2+.

  • Effects of Particle Size and Macro Morphology on Pellet Properties of Straight-Grate Induration Machine
    WEN Baoliang, LIU Yingcai, SONG Canyang, ZHANG Xiaoping, , YANG Jialong
    Mining and Metallurgical Engineering. 2026, 46(4): 203-209. https://doi.org/10.3969/j.issn.0253-6099.2026.04.031
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The effects of particle size and macro morphology on the comprehensive properties of pellets produced by the straight-grate induration machine were investigated. The results show that the particle size of finished pellets is mainly distributed within the range of 12－16 mm, accounting for more than 90%. Intact pellets account for 59.95%, while broken pellets and cracked pellets account for 24.71% and 15.35%, respectively. The crushing strength of intact pellets rises with an increase in particle size. As for the pellets with the same particle size, the macro morphology serves as the dominant factor determining their crushing strength. It is shown that intact pellets exhibit the highest crushing strength, whereas cracked pellets show the lowest crushing strength. The essential reason for the difference in crushing strength among pellets lies in the different bonding compactness of internal hematite grains. Large-sized intact pellets undergo insufficient oxidation and possess poor uniformity in internal structure. In terms of reduction performance, intact pellets with different particle sizes have negligible differences in reduction degree. For pellets with identical particle size, broken and cracked pellets feature a higher initial reduction rate, but present no obvious differences compared with intact pellets in terms of final reduction degree, reduction swelling index and anti-pulverization performance. Broken and cracked pellets suffer degraded mechanical properties and tend to damage the gas permeability of blast furnace burden during smelting, so their feeding proportion into the blast furnace should be strictly controlled. It is recommended that the proportion of intact pellets sized 12－14 mm be preferentially increased to balance pellet strength and metallurgical properties. This research can provide theoretical support for the optimization of pellet quality evaluation system and proportion of blast furnace burden.
  • Optimization Model for Roasting Parameters of High-Copper Low-Sulfur Concentrate Based on Response Surface Methodology
    LUO Xing, ZHAO Fucheng, JIA Kangle, FAN Haibao, PU Jun
    Mining and Metallurgical Engineering. 2026, 46(4): 210-214. https://doi.org/10.3969/j.issn.0253-6099.2026.04.032
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    By adopting central composite design (CCD) of response surface methodology (RSM), a binary quadratic regression prediction model was established, with  roasting temperature and oxygen concentration as influencing factors and copper leaching rate of calcine as the response value. It is shown that the prediction model presents a P value of 0.0182, adjusted determination coefficient of 0.8101, and signal-to-noise ratio of 7.3236, exhibiting favorable reliability and prediction accuracy. Roasting temperature has an extremely significant effect on copper leaching rate, while oxygen concentration brings insignificant effect, and their interaction is weak. The parameters were optimized via Design-Expert software, and the optimal roasting process parameters are obtained as follows: roasting temperature of 750 ℃ and oxygen concentration of 30%. Under such optimized parameters, the predicted copper leaching rate of calcine is 97.47%, while the copper leaching rate of calcine in industrial applications reaches 98.17%.
    • MATERIALS
  • Effects of Annealing Temperatures on Mechanical Properties and Intergranular Corrosion Behavior of Al-Cu-Mg-Ag Alloys
    WANG Shujuan, BAI Song, LIU Zhiyi
    Mining and Metallurgical Engineering. 2026, 46(4): 215-221. https://doi.org/10.3969/j.issn.0253-6099.2026.04.033
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    The effects of annealing temperatures on mechanical properties, intergranular corrosion resistance and microstructure of an Al-Cu-Mg-Ag alloy sheet were investigated by tensile tests, intergranular corrosion tests, electrochemical measurements, scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The results show that with an annealing time of 4 h, the annealing temperature increased from 335 ℃ to 395 ℃ can refine the recrystallized grains of alloy sheet and promote the dissolution of residual second-phase particles, which significantly enhances the mechanical properties of the alloy. Cube texture preferentially develops in specimens annealed at 335 ℃ for 4 h, whereas Goss texture becomes the dominant texture after annealing at 395 ℃ for 4 h. It is found that higher annealing temperatures lead to increased corrosion current density and negative shift of corrosion potential, which accelerates the intergranular corrosion rate and degrades the corrosion resistance of the alloy sheet.
  • Influence of Element Stoichiometry and Sintering Temperature on Lithium-Ion Conductivity of Sulfide Solid Electrolyte Li6-xPS5-xCl1+x
    ZHANG Jiaqiang, MAO Zexiao, LIAO Hong, LEI Gang, JU Bowei
    Mining and Metallurgical Engineering. 2026, 46(4): 222-225. https://doi.org/10.3969/j.issn.0253-6099.2026.04.034
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    Sulfide solid electrolyte Li6-xPS5-xCl1+x samples were prepared under varied combinations of element stoichiometry and sintering temperature. Performance characterizations were conducted to investigate the effects of processing parameters on ionic conductivity. The results reveal that the optimal parameter combination corresponds to the electrolyte with the chemical formula Li5.35PS4.35Cl1.65, being sintered at 500 ℃. This electrolyte delivers a lithium-ion conductivity of 11.05 mS/cm after cold pressing at 26 ℃. For electrolytes with identical stoichiometry, the lithium-ion conductivity of electrolyte increases first and then decreases as sintering temperature rises. Under the optimal sintering temperature, the lithium-ion conductivity of electrolyte exhibits an upward trend followed by a downward trend with the increase of halogen stoichiometric coefficient (1+x).
  • V-Y Co-doping for Construction of Coherent Interface and Electrochemical Performance of LiNi0.5Mn1.5O4
    HUANG Zhende, PENG Di, CHEN Zhihang
    Mining and Metallurgical Engineering. 2026, 46(4): 226-232. https://doi.org/10.3969/j.issn.0253-6099.2026.04.035
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    To enhance the rate capability and cycling stability of the high-voltage cathode material LiNi0.5Mn1.5O4 (LNMO), a V-Y co-doped LNMO cathode material was synthesized via the polymer soft-template method. The effects of V-Y co-doping on crystal structure, interfacial properties, and electrochemical performance were systematically investigated. The material was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) among other techniques, and the electrochemical properties were analyzed via galvanostatic charge-discharge, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The results indicate that V-Y co-doping induces the formation of disordered Fd3m phase by effectively regulating LNMO, facilitates the morphology evolution of spinel from regular octahedron to truncated octahedron, and constructs a coherent interface, which significantly enhances the lithium-ion diffusion rate and electronic conductivity. Moreover, V-Y co-doping reduces the Mn3+ content, suppresses Jahn-Teller effect and side reactions at the electrode/electrolyte interface, thereby enhancing the interfacial electrochemical stability. The 0.03V-Y sample (LiV0.03Ni0.47Y0.01Mn1.49O4) delivers an initial discharge capacity of 132 mAh/g at a 0.1C rate, retaining 94.7% of its capacity after 200 cycles. It also exhibits superior rate capability at a high rate of 5C. This study provides a novel approach for constructing a coherent interface and synergistically optimizing the electrochemical performance of LNMO via dual-element doping.
  • Effect of Boron Content on Microstructure and Wear Resistance of Fe-B-W Coatings by Ultra-High-Speed Laser Cladding
    XIA Jingyao, WEI Xiang, CHEN Zhiguo, TANG Min, QIN Yang
    Mining and Metallurgical Engineering. 2026, 46(4): 233-237. https://doi.org/10.3969/j.issn.0253-6099.2026.04.036
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    High-wear-resistance Fe-B-W coatings were fabricated on 65Mn steel substrates via ultra-high-speed laser cladding by regulating boron content. The effects of boron content on the microstructure, microhardness and tribological properties of Fe-B-W coatings were systematically investigated by using scanning electron microscopy, X-ray diffraction, microhardness tester and friction and wear tester. The results reveal that the Fe-B-W coatings are mainly composed of α-Fe phase and Fe2B phase, along with a small amount of W phase, Fe3B phase and Fe23B6 phase. Iron-boron compounds increase with the rising boron content, distribute in a network structure inside the coatings and gradually coarsen. The Fe-B-W coatings can greatly elevate the microhardness and wear resistance of 65Mn steel substrate. As boron content increases, the microhardness of the coatings rises gradually, while the friction coefficient and volumetric wear rate first decrease and then increase. The coating with 3.5% boron exhibits the lowest friction coefficient, and its volumetric wear rate also drops to the lowest, only 35.8% of that of the substrate, which demonstrates that Fe-3.5B-30W coating possesses optimal comprehensive performance. It is shown that the dominant wear mechanism of Fe-B-W coatings is abrasive wear.
  • MnO2 for High-Performance Energy Storage and Conversion: From Preparation Techniques and Modification Strategies to Device Performance
    ZHANG Zhiyong, ZENG Wenming, BAO Xinjun
    Mining and Metallurgical Engineering. 2026, 46(4): 238-246. https://doi.org/10.3969/j.issn.0253-6099.2026.04.037
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    This paper systematically reviews the application of manganese dioxide (MnO2) in the field of energy storage and conversion in terms of preparation techniques, modification strategies and device performance. Firstly, the regulation mechanisms of liquid-phase method, solid-phase method, sol-gel method, microfluidic etching and other approaches on the micromorphology and crystal structure of MnO2 are elaborated systematically. As for modification strategies, the functional mechanisms of element doping, carbon-based material compositing and microstructure design (including nanostructuring and hollow structure) for improving the electrical conductivity and structural stability of materials are discussed in detail. In the aspect of device performance, the practical effects of MnO2-based composites on elevating the specific capacity of lithium-ion batteries, optimizing the rate performance of supercapacitors, and boosting the catalytic activity of bifunctional electrocatalysts (ORR and OER) are further analyzed. On this basis, future development prospects are proposed from the perspectives of green synthesis technologies, high-loading flexible device development and multi-functional integration, aiming to provide references for the rational design of high-performance MnO2-based energy materials.
  • Synergistic Construction of Ion/Electron Conductive Networks via Solid-Phase Mechano-fusion and CVD to Achieve Highly Stable Silicon Oxide Anodes
    CHEN Lifu, YANG Lezhi, LIU Xiaoxiong, GU Zhengguo, WANG Shuang, CHEN Tao, LIU Yunfeng, YU Gangjie
    Mining and Metallurgical Engineering. 2026, 46(4): 247-253. https://doi.org/10.3969/j.issn.0253-6099.2026.04.038
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Silicon oxide (SiOx, 0<x<2) anode suffer from low intrinsic conductivity, unstable solid electrolyte interphase (SEI), and mechanical stress failure caused by volume expansion during cycling. To tackle these challenges, a modification strategy was proposed, featuring the synergistic regulation of a surface fast-ion coating layer and an in-situ constructed three-dimensional (3D) carbon nanotubes (CNTs) conductive network. Nano-sized Al2O3 was uniformly coated on the surface of SiOx via solid-phase mechano-fusion technology, and also converted into a fast ionic conductor layer with high ionic mobility during electrochemical activation. Subsequently, a 3D CNTs conductive network was constructed on the outer layer of the material via chemical vapor deposition (CVD). Structural and morphological characterizations reveal that the in-situ grown CNTs are tightly interwined on the particle surfaces and within the interstices, establishing efficient electron transport pathways. The synergistic effect of LiAlO2 and CNTs greatly enhances interfacial ion transport capacity and overall electronic conductivity. Electrochemical measurements indicate that the modified SiOx@Al2O3@CNTs material exhibits outstanding electrochemical performance. It delivers discharge specific capacities of 1283.2, 1255.4, 1236.4, 1201.0 and 1165.8 mAh/g at current densities of 0.2C, 0.5C, 1C, 2C and 4C, respectively. Furthermore, it retains a high specific capacity of approximately 1000 mAh/g after 200 cycles at 0.1C, far exceeding 552.3 mAh/g of unmodified SiOx. This study has verified the synergistic enhancement of ion/electron conductive network, and provides a promising technical solution for development of high-energy-density and highly stable silicon-based anode materials.
  • Effect of Interpass Temperature on Microstructure and Wear Performance of Arc Surfacing Layer on High Chromium Cast Iron
    LOU Yumin, CUI Yimin, KONG Xiangzhi, ZHOU Fan, WU Jianbo, HU Lei
    Mining and Metallurgical Engineering. 2026, 46(4): 254-259. https://doi.org/10.3969/j.issn.0253-6099.2026.04.039
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    By adopting metal inert gas (MIG) welding, high-chromium cast iron surfacing specimens with preheating and interpass temperatures ranging from 150 ℃ to 350 ℃ were fabricated on the surface of Q345B steel plates using TDCr27-58 high-chromium cast iron flux-cored hardfacing wires. The influence of interpass temperature on macroscopic morphology, microstructure and wear performance of the surfacing layer was investigated via penetrant testing (PT), SEM and pin-on-disk wear test. The results indicate that the increase of interpass temperature improves the fluidity of molten pool and significantly reduces welding spatter and cracks. The surfacing layer mainly consists of primary dendritic austenite and intergranular eutectic M7C3 carbides. The average hardness of the surfacing layer rises with increasing interpass temperature, reaching 716.6HV at 350 ℃, which is 25.2HV and 39.0HV higher than that obtained at 250 ℃ and 150 ℃, respectively. The mass loss at an interpass temperature of 150 ℃ is approximately 63% larger than that at 350 ℃, exhibiting severe spalling pits and adhesive wear characteristics. A higher interpass temperature can extend high-temperature holding duration, accelerate the diffusion of C and Cr atoms, and promote the sufficient precipitation and growth of eutectic carbides, thereby improving the hardness and wear resistance of the surfacing layer.
  • Rheological Properties of Coarse-Grained SiC Slurry and Direct Ink Writing
    XU Qikai, LIU Zirui, ZHOU Hongli, WANG Richu, PENG Chaoqun, WANG Xiaofeng
    Mining and Metallurgical Engineering. 2026, 46(4): 260-266. https://doi.org/10.3969/j.issn.0253-6099.2026.04.040
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To advance the application of direct ink writing (DIW) in SiC ceramic manufacturing, with coarse-grained SiC powder (D50=44 μm) as raw material, the regulation rules of dispersant, slurry pH value, solid volume fraction and thickener on the rheological properties of slurry were systematically investigated, and high-solid-content slurry suitable for DIW was prepared. The printing parameters were then optimized based on finite element simulation, and the printability of the slurry was quantitatively evaluated via linear fluid span test. The results show that with pH of 10-11, an addition of 1.4% polyacrylic acid (PAA) dispersant can greatly reduce slurry viscosity, and lead to the maximum solid volume fraction of the slurry up to 55%. While an addition of 0.05% methylcellulose (MC) thickener can effectively improve the structural strength of the slurry, bringing in optimal comprehensive printing performance. By adopting a 1.2 mm nozzle with the maximum printing span controlled within 6.3 mm, an intact three-dimensional lattice ceramic green body can be fabricated without collapse.
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