This study investigates grinding media behavior and grinding efficiency in a laboratory-scale ball mill under different rotation speeds to identify energy-efficient operating conditions in ball mill grinding operations. Grinding efficiency is evaluated in terms of the effectiveness of energy transfer into particle breakage, as quantified by PBM-derived breakage-rate characteristics, rather than by conventional metrics based solely on energy consumption. Batch grinding tests were conducted at several fractions of the critical speed, and a Population Balance Model (PBM) was calibrated for each operating condition to quantify the corresponding breakage-rate characteristics. In parallel, Discrete Element Method (DEM) simulations were performed to analyze the motion of grinding media as a function of rotation speed. Media motion descriptors derived from DEM were integrated with the PBM-based breakage parameters to interpret efficiency trends. The results show that grinding efficiency does not increase monotonically with rotation speed; instead, an optimal operating region exists within the investigated range due to the balance between impact-dominated and surface-contact-dominated motion regimes. By linking DEM-quantified media behavior indicators with PBM-derived breakage-rate coefficients, the proposed integrated framework enables physics-based estimation of the optimal rotation speed region. This methodology provides a transferable basis for analyzing and improving grinding efficiency in ball mill grinding operations.

With the significant increase in lithium demand and production, alternative resources such as lithium-bearing clays have increasingly attracted attention and have been considered as a potential source. In addition to conventional Li recovery methods such as acid treatment and roasting, more economical and environmentally friendly techniques such as mechanical activation followed by water leaching are also being considered. In Türkiye, wastes from boron processing plants, containing approximately 900 ppm of lithium and mainly of dolomitic clays and unrecovered boron minerals (~10-13% of waste), are considered as a potential lithium source. However, due to high dolomite and boron mineral contents, the waste material may release significant amounts of alkaline earth ions such as Na<sup>+</sup>, K<sup>+</sup>, Mg<sup>2+</sup>, Ca<sup>2+</sup>, and B<sub>2</sub>O<sub>3</sub> during leaching, which may interfere with lithium extraction from the solution. In this study, the leaching behavior of lithium, alkali ions, and other possible elements (e.g., B<sub>2</sub>O<sub>3</sub>, Fe<sup>3+</sup>, and Al<sup>3+</sup>) from both raw clay waste and mechanically activated forms of this waste material was investigated in detail. The results showed that water leaching without sodium salt of activated waste samples achieves about 44.7–57.7% lithium recovery, yielding high lithium concentrations (80–115 ppm), low levels of alkali ions (4430 ppm Na<sup>+</sup>, 114 ppm K<sup>+</sup>, 20 ppm Ca<sup>2+</sup>, and 7 ppm Mg<sup>2+</sup>), and almost no detectable Fe<sup>3+</sup> (<0.2 ppm) or Al<sup>3+</sup> (0.07 ppm) ions. On the other hand, a single problem was encountered where 0.95 % of B<sub>2</sub>O<sub>3</sub> concentrations did not decrease in water leaching at even room temperature.

Tungsten ores exhibit high brittleness and a tendency to sliming, which significantly limits the application of high-pressure grinding rolls (HPGRs) in tungsten ore processing. To explore the feasibility of applying HPGRs, this study conducted a comparative experiment between HPGRs and jaw crushers for tungsten ore comminution. The experiment employed the tungsten ore from a mine in Jiangxi Province, China, which had been pre-sorted by sensor-based sorting. Particle size distribution and mineral liberation of the two crushed products were systematically characterized. Additionally, particle morphologies and surface roughness were examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Combining these observations with grinding kinetics, the influence of the two crushing methods on subsequent grinding processing was deeply evaluated. Particle-size-screened gravity separation tests were also performed. Results indicate that HPGRs accelerate the liberation of tungsten minerals. When combined with pre-screening before grinding, HPGRs significantly enhance rod mill grinding efficiency and mitigate the sliming phenomenon, resulting in a 3.22 percentage point increase in gravity separation recovery. The findings provide data and reference for the industrial application of HPGRs in tungsten ore processing.

This study investigates the hydrogenation of cyclopentadiene and 1-hexene over skeletal nickel catalysts modified with various metallic additives. The results demonstrate the high catalytic activity of skeletal nickel in promoting the migration of the –C=C– bond during the hydrogenation of 1-hexene. It was found that the addition of Fe, Pd, Sn, and Ag enhances the migration coefficient (Kmigr), while Ti, Mo, and Ti–Mo exert little to no influence on this process. The catalytic performance in the hydrogenation of cyclopentadiene is strongly affected by the nature of the modifying elements incorporated into the initial alloy. Additives such as Cu, Zn, Mo–Cu, Bi, and Mo significantly improve both the activity (W = 73–158 cm³/min·g Ni) and selectivity (Ksel = 0.93–0.98) of the reaction, facilitating the selective conversion of cyclopentadiene to cyclopentene. In contrast, Ti, Sn, and Cr–Cu additives do not substantially enhance either the activity or selectivity of the catalyst. The study highlights that the electronic and structural effects introduced by the modifying elements play a crucial role in determining the catalytic behavior of skeletal nickel systems. These findings provide valuable insights into the design of efficient nickel-based catalysts for selective hydrogenation processes and underline the potential of multi-component catalytic systems in optimizing reaction pathways. Overall, the research expands the understanding of structure–activity relationships in skeletal metal catalysts and demonstrates how tailored additive selection can improve both hydrogenation efficiency and product selectivity.

This study investigates the effect of fly ash substitution on compressive strength in cemented paste backfill (CPB) systems using an integrated framework combining predictive machine learning, explainable artificial intelligence, and causal machine learning approaches. A dataset comprising 116 experimental CPB mixtures prepared with mineral processing tailings from a Pb–Zn underground mine and fly ashes from different thermal power plants was analyzed. The maximum compressive strength reached 10.33 MPa at 90 days of curing. The cross-validated XGBoost model achieved an R² of 0.58 and successfully predicted strength values up to 9.73 MPa. Causal analysis indicated an average treatment effect of approximately 0.28 MPa per 1% fly ash substitution, although the effect showed substantial heterogeneity across physicochemical conditions. Global and local SHapley Additive exPlanations (SHAP) analyses identified curing time as the dominant factor controlling strength development, emphasizing the importance of late-age performance in fly ash–containing systems. The fly ash ratio itself was not a primary explanatory variable; instead, chemical composition, particle size distribution, and specific gravity played decisive roles. These findings demonstrate that fly ash performance in CPB systems cannot be reliably evaluated using dosage-based approaches alone and should be optimized by considering physicochemical characteristics and curing conditions. The proposed explainable and causal data-driven framework provides a practical decision-support tool for sustainable utilization of mineral processing by-products in cement-based systems.

Alkyl ether amine exhibits significant potential as an efficient collector for silica removal in collophane beneficiation. However, the presence of iron ions often significantly impairs the desilication performance of alkyl ether amines. To elucidate the influence of iron ions on the surface properties and flotation behavior of quartz and apatite particles using alkyl ether amine (EA) as the collector, micro-flotation experiments, solution chemistry calculations, contact angle measurements, zeta potential analyses, and X-ray photoelectron spectroscopy (XPS) were conducted. The findings showed that iron ions considerably decreased the floatability of quartz while having minimal impact on the floatability of apatite. In particular, increasing the concentration of iron ions from 0 to 8.0×10<sup>-4</sup> mol/L reduced the quartz recovery rate from 84.6% to approximately 10% at pH 6. Contact angle analysis indicated that the adsorption of iron ions weakens EA's ability to enhance the hydrophobicity of quartz. Zeta potential measurements verified that iron ions modified the EA's adsorption behavior. XPS results further demonstrated that iron ions were chemically adsorbed onto quartz with higher binding affinity than EA, leading to their preferential adsorption on the quartz surface and consequently inhibiting EA adsorption. Therefore, the presence of iron ions reduces the separation efficiency in cationic reverse flotation of quartz from apatite.

In this study, following characterization, the leaching behaviour of scandium from a clayey laterite ore sample in sulfuric acid solutions under atmospheric pressure was investigated. The ore sample was characterized using various techniques and it was found to be a low-grade, predominantly smectite-containing nickel laterite ore with 71 ppm Sc and 6340 ppm Ni. Nickel in the ore sample is associated mainly with the clay (smectite/serpentine group) minerals, goethite and asbolane, while scandium is associated with goethite and silicate phases. Following characterization, the leaching behaviour of scandium, together with nickel, iron, magnesium, and aluminum, was determined under different experimental conditions (H2SO4 concentration: 0.1-4 M, leaching temperature: 20-90°C, leaching time: 2.5-240 minutes), and the leaching efficiencies of Sc, Ni, Fe, Mg, and Al found under the selected conditions (4 M H2SO4, 90°C, 60 min.) were 88.1%, 91.6%, 64.3%, 87.5%, and 66.2%, respectively. The leaching kinetics of scandium was determined to be controlled by a mixed mechanism with an activation energy of 23.2 kJ/mol. The preliminary scandium extraction experiments performed on the loaded solution obtained after leaching under selected conditions showed that 98.6% of scandium in the solution could be selectively separated against nickel and iron using an extractant containing 5% di(2-ethylhexyl) phosphoric acid (D2EHPA) in kerosene. The preliminary experiments also showed that scandium could also be selectively separated from the loaded solution and directly from the leach pulp by using an ion-exchange resin impregnated with D2EHPA.

The selective flotation of quartz and feldspar under weakly alkaline conditions was investigated, with carboxymethyl starch sodium (CMS-Na) employed as a depressant and polyether amine (PEA) as a collector. Micro-flotation tests demonstrated that CMS-Na exhibited strong selective depression of feldspar while maintaining high quartz recovery. Optimal separation conditions were achieved at pH 9.0 with 30 mg/dm3 CMS-Na and 4.0×10-4 mol/dm3 PEA, resulting in feldspar recovery decreasing sharply to 12.51% while quartz recovery remained high at 92.17%. The selectivity index (SI) increased significantly from 3.03 to 9.07, highlighting enhanced separation efficiency. Spectroscopic analyses, including FTIR, Raman, and XPS, revealed that CMS-Na selectively adsorbed onto feldspar surfaces mainly via coordination with Al-sites, with a small portion additionally forming hydrogen bonds with -Al-OH or -Si-OH, effectively suppressing its flotation. Conversely, CMS-Na exhibited limited interaction with quartz, enabling subsequent PEA adsorption. XPS data further confirmed that PEA adsorption on quartz and feldspar occurs via electrostatic and hydrogen bonding interactions, with CMS-Na selectively inhibiting PEA adsorption on feldspar. These results underscore CMS-Na's role as an environmentally friendly and effective depressant, enabling efficient separation of quartz and feldspar without hazardous chemicals like hydrofluoric acid. This study offers a sustainable approach to mineral resource utilization in industrial applications.

To address the demand for efficient pulp conditioning technology in coal slime flotation, this paper designs a combined pulp conditioning device based on jet mixing, pipeline mixing, and drop plate mixing. Through a combination of COMSOL numerical simulation and physical experiments, parameter optimization tests were conducted for each stage of jet, pipeline, and drop plate. The pulp conditioning effect was verified through flotation tests. The results indicate that when the ratio of the incident flow rate to the instantaneous mixing volume in the tank is 0.414, an optimal flow field is achieved in the tank for the mixing of reagents and pulp. Increasing the number of mixing units within the pipeline mixing enhances the turbulence intensity of the fluid, thereby further improving the contact probability between reagents and mineral particles. When the angle of the drop plate is set at 15°, particles are more evenly distributed on the baffle plate, which can increase the pretreatment time and enhance the effect of the baffle bars. Compared with the slurry flotation of 1.5 L single tank flotation machine, the flotation test was carried out on the slurry after the slurry was adjusted by the Jet - Pipeline - Drop plate combined slurry adjustment device. The yield of clean coal was increased by 6.85 %, and the recovery rate of clean coal combustible was increased by 8.85 %.

The efficient solid-liquid separation of fine-particle slurries is a significant challenge in mineral processing. In this study, the influence of centrifugal flow conditions and flocculation parameters on fine particle recovery was systematically investigated using cationic polyacrylamide (CPAM) and a multi-stage centrifugal cyclosizer. Static flocculation–sedimentation experiments, centrifugal classification tests, and response surface methodology were combined to evaluate recovery performance. The results showed that within a certain range, the larger the flocculant molecular weight and dosage, the better the static flocculation sedimentation performance, while appropriate centrifugal flow conditions further enhanced fine particle recovery. Response surface experiments indicated that the cyclosizer flow rate exerted the most significant influence on recovery, followed by polymer molecular weight and dosage, with a significant interaction observed between flow rate and polymer dosage. Additionally, microscopic observation and numerical simulation of the cyclosizer were combined to show a method to express the shear resistance strength of floccules using the characteristics of the flow field. In the flocculation hydrocyclone validation experiments, the addition of PAM at a dosage of 70 g/t resulted in a 2.85% increase in underflow concentration and an 8.34% improvement in yield compared with the non-PAM condition. These results indicate that centrifugal separation equipment can regulate floc stability and recovery by altering the shear rate and centrifugal force within the flow field. Therefore, achieving an appropriate balance between flow rate and flocculation intensity is essential for enhancing underflow yield.