Search Results (62)

The use of high-pressure grinding rolls (HPGRs) is increasing in the ore industries as advanced technology is available for this type of comminuting. There are important parameters in these devices, which have many effects on productivity. One of the main reasons for damage on the rolls and, therefore, decreases in the machine’s productivity and efficiency is surface wear. This phenomenon must be carefully understood so that it can be controlled as much as possible through the readjustment and optimization of the effective parameters. In this research, the wear mechanism of HPGRs in a production line for iron ore concentrate was investigated. The results showed that there was greater wear at the center of the rolls and that changes to the chemical and physical properties of the incoming iron compared to the design condition reduced the rolls’ lives. The results showed a failure to perform appropriate mechanical adjustment and improper repair and maintenance. Full article

Electrostatic separation is a promising technology for the recovery of valuable metals from electronic waste, particularly from printed circuit boards (PCBs). This study explores the application of electrostatic separation for the selective recovery of metallic and non-metallic fractions from crushed PCBs (PCBs). The process exploits the differences in electrical properties between conductive metals and non-conductive polymers and ceramics, facilitating their separation through applied electric fields. The raw materials were pre-treated via mechanical comminution using shredders and hammer mills to achieve an optimal particle size distribution (<3 mm), which enhances separation efficiency. Ferrous materials were removed prior to electrostatic separation to improve process selectivity. Key operational parameters, including particle size, charge accumulation, environmental conditions, and separation efficiency, were systematically analysed. The results demonstrate that electrostatic separation effectively recovers high-value metals such as copper and gold while minimizing material losses. Additionally, the process contributes to the sustainability of e-waste recycling by enabling the recovery of non-metallic fractions for potential secondary applications. This work underscores the significance of electrostatic separation as a viable technique for e-waste management and highlights optimization strategies for enhancing its performance in large-scale recycling operations. Full article

This study was conducted on a copper porphyry deposit located in Espinar, Cusco (Peru), with the objective of developing and comparing predictive models for processing capacity in SAG grinding circuits. A total of 174 samples were used for the JK Drop Weight Test (JKDWT) and 1172 for the Bond Work Index (BWi), along with 36 months of operational plant data. Three modeling methodologies were evaluated: DWi-BWi, SGI-BWi, and SMC-BWi (Mia, Mib), all integrated into a geometallurgical block model. Validation was performed through reconciliation with actual plant data, considering operational constraints such as transfer size (T₈₀) and maximum throughput (TPH). The model based on SMC parameters and BWi showed the best predictive performance, with a root mean square error (RMSE) of 143 t/h and a mean relative deviation of 1.5%. This approach enables more accurate throughput forecasting, improving mine planning and operational efficiency. The results highlight the importance of integrating geometallurgical and operational data to build robust models that are adaptable to ore variability and applicable to both short- and long-term planning scenarios. Full article

Narrow-vein deposits have historically been valuable in producing gold, tin, copper, silver, lead, and zinc. Developing these mineral resources is sometimes challenging due to economic and safety concerns. Given the small to medium scale of production, narrow-vein mining could be labor-intensive with increased exposure of the miners to hazardous conditions. A safe, mechanized, efficient, and sustainable method can be invaluable to operators looking to develop narrow-vein mineral resources. The comminution circuit (consisting of crushing and grinding) is downstream of most mineral resources’ extraction processes. Comminution is significantly energy-intensive, consuming almost half of the energy supplied to a mineral-processing activity. Thus, several engineers have investigated the continued development of sustainable narrow-vein mining and comminution technologies. This journal article focuses on a developed innovative, safe, mechanized, and continuous narrow-vein mining technology that has further made accessing narrow-vein deposits more economically feasible and efficient while reducing dilution of ores. The article also extensively presents the impact of this new mining approach on the daily production of the operation and the observed particle size distributions of the day-to-day operational output. Subsequently, the article evaluates and presents the impact of the new procedure of mineral extraction on the resultant size of the cuttings generated as well as the expected energy input of the comminution process downstream of the mining operation. The novelty of the mining method upon which this work is based is improved capital expenditure and reduced dilution. With the new mining method, otherwise-uneconomic narrow-vein deposits can be accessed. Full article

The feed industry is characterized by high energy consumption during the grinding stage, where hammer mills can account for up to 50% of total electricity usage; furthermore, efficiency analyses are based only on the classical equations reported in the literature. In this context, the present theoretical-applied research aimed to improve the efficiency of a plant operating below its nominal capacity. To achieve this, a comprehensive mathematical model was developed, integrating power and grain disintegration equations while overcoming the limitations of classical comminution theories. The model incorporates key factors such as feed rate, moisture content, absorbed power and hammer wear. Additionally, specific correction factors for temperature ($K_t$) and mechanical degradation ($K_d$) were introduced to accurately represent real operating conditions. The study was based on extensive measurements of electrical current, power factor, energy consumption, particle size distribution and thermal variations under different load conditions. The statistical analysis, which included ANOVA, ANCOVA and multiple regressions, demonstrated a predictive accuracy of 98% (R²) and a pseudo-R² of 89%. This high correlation allowed for an 18% reduction in energy consumption equivalent to 4 kWh/t and up to a 30% improvement in particle size uniformity, surpassing typical factory performance. The findings highlight that integrating operational, thermodynamic and wear-related factors enhances the robustness of the model, promoting more reliable energy-management practices in hammer mills. Consequently, the results confirm that the developed model serves as a scientifically robust, efficient and applicable tool for improving energy efficiency and reducing environmental impacts in the agri-food industry. Full article

Physical pretreatments play a crucial role in reducing the recalcitrance of lignocellulosic biomass, facilitating its conversion into fermentable sugars for bioenergy and chemical applications. This study critically reviews physical pretreatment approaches, including mechanical comminution, irradiation (ultrasound, microwave, gamma rays, and electron beam), extrusion, and pulsed electric field. The discussion covers the mechanisms of action, operational parameters, energy efficiency, scalability challenges, and associated costs. Methods such as ultrasound and microwave induce structural changes that enhance enzymatic accessibility, while extrusion combines thermal and mechanical forces to optimize hydrolysis. Mechanical comminution is most effective during short periods and when combined with other techniques to overcome limitations such as high energy consumption. Innovative approaches, such as pulsed electric fields, show significant potential but face challenges in large-scale implementation. This study provides technical and strategic insights into developing more effective physical pretreatments aligned with economic feasibility and industrial sustainability. Full article

This study examines the conversion of an overflow ball mill into a new discharge system via Discrete Element Method (DEM) and Smoothed Particle Hydrodynamics (SPH) simulations, demonstrating significant performance improvements. The methodology integrates SPH to assess the effects of the slurry on energy dissipation, power loss, breakage rates, and material transport. The findings highlight significant operational inefficiencies in the overflow setup, extensive dead zones, and excessive charge volume that hinder milling efficiency by limiting grinding media interaction with the ore and reducing energy for comminution. Additionally, slurry pooling shifts the center of gravity, causing torque losses and direct material bypass to the discharge zone. Our simulations replicate these challenges and benchmark them against industrial-scale operations, identifying critical charge excesses that constrain throughput and elevate power consumption. The new proposed discharge system decouples the filling charge from the evacuation mechanism, releasing the effective volume in the mill, in addition to tackling common issues in the traditional grate discharge setups like backflow and carry-over. This arrangement substantially improved grinding efficiency, as demonstrated by enhanced breakage rates and diminished specific energy consumption. The results provide a robust framework for mill design and operational optimization, underscoring the value of integrated slurry behavior analysis in mill performance enhancement. Full article

Roping is a hydrocyclone failure mode that reduces separation efficiency, negatively impacting both the comminution circuit and downstream flotation processes. Therefore, detection of roping as early as possible is crucial in maintaining the normal performance of physical separation and linked processes. Most importantly, instead of detecting roping after it happens, could roping be predicted even before it arises? This review examines various detection methods, including mechanical, tomography, vibration, acoustic, and image processing, highlighting their cost and ability to monitor parameters like air core size, spray angle, and solid concentration. While most current methods detect roping only after it happens, predictive approaches could save time and costs. A promising solution combines pressure and vibration sensing with advanced signal processing, showing early potential to transform roping prediction and improve operational efficiency. This review highlights research gaps across various methods, underscores the importance of developing predictive capabilities for hydrocyclone operations, and outlines the essential conditions and future priorities for achieving roping prediction. Full article

Objective: This study aims to evaluate and compare the biomechanical performance of two Kirschner (K) wire configurations—the intra-focal and interfragmentary techniques—for the fixation of dorsally displaced distal radius fractures. The study also assesses the impact of K-wire diameter (1.6 mm vs. 2.0 mm) on mechanical stability. Methods: Sixty fresh turkey tarsometatarsus bones were selected and divided into four groups based on the K-wire configuration and diameter used. Fractures were created at standardized locations, and each bone was stabilized using either the intra-focal also known as modified Kapandji (Ka) or interfragmentary technique. Mechanical testing, including axial compression and flexion tests, was performed to assess the biomechanical stability of each configuration. Results: The interfragmentary configuration consistently demonstrated superior biomechanical performance compared to the intra-focal technique. Specifically, the use of 2.0 mm K-wires resulted in significantly higher axial stiffness (13.28 MPa) and load at break (3070 N) compared to the 1.5 mm wires. Confidence intervals further supported the robustness of these findings. The interfragmentary technique, especially with thicker K-wires, provided greater load-bearing capacity and stiffness. Conclusion: The interfragmentary technique with 2.0 mm K-wires offers superior mechanical stability compared to the intra-focal technique, making it the preferred choice for stabilizing comminuted extra-articular distal radius fractures. These findings suggest that adopting this technique may reduce the risk of postoperative complications such as fracture displacement or malunion. Further research involving osteoporotic bone models and clinical trials is recommended to validate these findings in real-world settings. Full article

The surface chemical properties of Lepidolite-1M crystals are closely related to their flotation properties. This paper uses density functional theory (DFT) to analyze the band structure, population, and state density of ideal Lepidolite-1M crystals. The results show that lepidolite-1M is an insulator, and its most probable positively charged active site is Al, and its negatively charged active sites are O and F. To further investigate the adsorption mechanism of Lepidolite-1M during comminution and flotation processes, we calculated the surface energy, population, state density, and differential charge density of its most common (001) surface. The results show that its surface energy is 0.9934 J/m², occurred in the valence electron configurations, population values, and bond lengths of the surface atoms. Furthermore, oxygen atoms on the (001) surface showed different activities, with F and O atoms in the lithium-rich region showing significant electron enrichment. Overall, our results demonstrated that anion collectors react mainly with the Al sites on the surface of Lepidolite-1M, and the cationic collectors and metal ion activators can be adsorbed on the surface of Lepidolite-1M to produce better trapping and activation capabilities. Full article

This study explored the impact of microwave pretreatment on the grinding efficiency of bastnaesite ore using a stirred mill. Bastnaesite ore was prepared using a staged crushing and sieving process, followed by microwave pretreatment in a specially designed microwave furnace system. Representative samples of the crushed ore underwent stirred mill grinding, with power draw measurements recorded and adjusted to reflect only the specific energy input required for grinding. Particle size distribution was analyzed periodically using laser particle size analysis. In addition, a Box–Behnken design was used to statistically assess the effects of various parameters on the results, ensuring a robust analysis of the factors influencing energy consumption and particle size reduction. The findings reveal that microwave pretreatment significantly influenced specific energy and product P₈₀, with SEM analyses showing increased microcracking and porosity and XRD analyses suggesting possible mineralogical alterations. This enhancement was also proved via statistical tools and analyses such as Design Expert software Ver. 13 and ANOVA. In summary, the research concludes with the following critical points: (1) Microwave pretreatment was found to reduce the energy consumption required for bastnaesite grinding by 27%. (2) Following pretreatment, bastnaesite achieved a 25% finer product size under identical grinding conditions. (3) Structural and compositional changes in bastnaesite after grinding were confirmed through scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. (4) Based on these analyses, potential mechanisms for the observed energy savings and product size reductions have been suggested. Additionally, we have enhanced the Abstract to better highlight the methods used in the study. This investigation not only advances our understanding of microwave-assisted comminution but also opens avenues for future research on optimizing and implementing this technique in large-scale mining operations. Full article

The texture of meat is one of the most important features to mimic when developing meat analogs. Both protein source and processing method impact the texture of the final product. We can distinguish three types of mechanical tests to quantify the textural differences between meat and meat analogs: puncture type, rheological torsion tests, and classical mechanical tests of tension, compression, and bending. Here, we compile the shear force and stiffness values of whole and comminuted meats and meat analogs from the two most popular tests for meat, the Warner–Bratzler shear test and the double-compression texture profile analysis. Our results suggest that, with the right fine-tuning, today’s meat analogs are well capable of mimicking the mechanics of real meat. While Warner–Bratzler shear tests and texture profile analysis provide valuable information about the tenderness and sensory perception of meat, both tests suffer from a lack of standardization, which limits cross-study comparisons. Here, we provide guidelines to standardize meat testing and report meat stiffness as the single most informative mechanical parameter. Collecting big standardized data and sharing them with the community at large could empower researchers to harness the power of generative artificial intelligence to inform the systematic development of meat analogs with desired mechanical properties and functions, taste, and sensory perception. Full article

Polyaxial locking systems are widely used for strategic surgical placement, particularly in cases of osteoporotic bones, comminuted fractures, or when avoiding pre-existing prosthetics. However, studies suggest that polyaxiality negatively impacts system stiffness. We hypothesize that a new plate design, combining a narrow plate with asymmetric holes and polyaxial capabilities, could outperform narrow plates with symmetric holes. Three configurations were tested: Group 1 with six orthogonal screws, and Groups 2 and 3 with polyaxiality in the longitudinal and transverse axes, respectively. A biomechanical model assessed the bone/plate/screw interface under cyclic compression (5000 cycles) and torsion loads until failure. Screws were inserted up to 10° angle. None of the groups showed a significant loss of stiffness during compression (p > 0.05). Group 1 exhibited the highest initial stiffness, followed by Group 3 (<29%) and Group 2 (<35%). In torsional testing, Group 1 achieved the most load cycles (29.096 ± 1.342), while Groups 2 and 3 showed significantly fewer cycles to failure (6.657 ± 3.551 and 4.085 ± 1.934). These results confirm that polyaxiality, while beneficial for surgical placement, reduces biomechanical performance under torsion. Despite this, no group experienced complete decoupling of the screw–plate interface, indicating the robustness of the locking mechanism even under high stress. Full article

Grinding is an important process of ore beneficiation that consumes a significant amount of energy. Pretreating ore before grinding has been proposed to improve ore grindability, reduce comminution energy, and enhance downstream operations. This paper investigates hybrid thermal mechanical pretreatment to improve iron ore grinding behavior. Thermal pretreatment was performed using conventional and microwave approaches, while mechanical pretreatment was conducted with a pressure device using a piston die. Results indicate that conventional (heating rate: 10 °C; maximum temperature: 400 °C), microwave (2.45 GHz, 1.7 kW, 60 s), and mechanical (14.86 MPa, zero delay time) pretreatments improved the studied iron ore grindability by 4.6, 19.8, and 15.4%, respectively. Meanwhile, conventional-mechanical and microwave-mechanical pretreatments enhanced the studied iron ore grindability by 19.2% and 22.6%, respectively. These results suggest that stand-alone mechanical pretreatment or microwave pretreatment may be more beneficial in improving the grinding behavior of the studied fine-grain iron ore sample. The results of the mechanical pretreatment obtained in this study may be used in a simulation of the HPGR system for grinding operations of similar iron ore Full article

A non-reducible tibial tuberosity fracture is a rare complication of tibial tuberosity transposition performed during correcting of medial patella luxation (MPL) in dogs. This condition severely disrupts the quadriceps extensor mechanism, leading to significant pelvic limb lameness. An 11-year-old, 1.8 kg spayed female Yorkshire Terrier sustained a comminuted left tibial tuberosity fracture during surgical correction of an MPL. Six months after surgery, the dog was markedly lame and unable to extend the left stifle. Radiographs revealed patella alta and resorption of the fragmented tibial tuberosity. A composite frozen allogeneic calcaneal tendon–bone block was utilized to reconstruct the tibial tuberosity and reattach the patellar ligament. Initial postoperative radiographs confirmed restoration of a normal patellar ligament to patella length ratio (1.42). Both the allogeneic bone used for tibial tuberosity reconstruction and the tendon used to reattach the patellar ligament were successfully integrated. The dog regained satisfactory limb function without recurrence of patella luxation, as reported by the owners 29 months postoperatively. The use of a calcaneal tendon–bone allograft effectively restored the functional integrity of the quadriceps extensor mechanism, providing a viable option for addressing quadriceps insufficiency resulting from the loss of the osseous tibial insertion. Full article