Grinding Mill Research Articles

Exploring the Link between HY Wet Ball Mill Work Index and Grinding Energy Consumption

Exploring the Link between HY Wet Ball Mill Work Index and Grinding Energy Consumption

Formation of requirements for impact resistance and wear resistance of grinding balls

The article presents the results of a study of the operation processes of steel grinding balls in semi-autogenous grinding mills (SAG). It was determined that the balls experience both abrasive and impact loads. The properties of steel grinding balls with the same production technology are determined by the chemical composition and the formed microstructure over the entire cross-section of the ball. Balls made using 3 different technologies were studied. The balls of sets 1 and 2 show high hardness values at the surface, sufficient to ensure good resistance to wear during operation, and a sharp decrease in hardness at a distance of ~(15–20) mm from the surface as the volume of pearlite structures increases. At the same time, the balls of the 1st and 2nd sets showed low values of impact strength and insufficient resistance to impact. The lowest hardness values from the surface to the center were observed for set 3. Also, the highest mass loss during the abrasive wear test was recorded for set 3, which is explained by the lowest hardness values. The balls of set 3 showed higher values of impact strength and no splitting during the ball-on-ball test, which is explained by the soft ferrite-pearlite structure both on the surface and across the cross section of the ball, due to the reduced carbon content and the presence of nickel in the chemical composition. At the same time, the balls from set 3 showed the worst result in terms of abrasive wear. In the course of the conducted research, it was established that for successful operation in SAG, steel grinding balls must have a surface with high hardness due to the martensitic structure and a viscous core with a ferrite-pearlite structure. A promising direction in the development of technology for the production of steel grinding balls will be to obtain a steel ball microstructure that decreases uniformly from the surface to the center, which will allow maintaining high wear resistance and increasing the resistance to ball splitting

Расчетно-экспериментальное исследование и идентификация матричной модели струйного измельчения сыпучих материалов

Grinding powders in jet mills makes it possible to obtain materials uncontaminated by wear products of grinding media to prepare pure products in chemical and pharmaceutical industries. It should be noted that for different technologies, the requirements for the granulometric composition of powders vary significantly, and to meet these requirements, specific approaches are often required. Experimental determination of optimal conditions to obtain new powders is often associated with significant costs, which is not always justified from an economic point of view. Mathematical modeling allows us to obtain effective solutions in a shorter time and at lower costs in most cases. Thus, the development of adequate models, methods of calculation and optimization of jet grinding technology is an urgent scientific and practical task. To simulate grinding, a matrix methodology is used to describe technological processes. To identify the model, the results of specially conducted experimental studies are used. During experimental studies, the granulometric compositions of powders after single and multiple grinding in a jet mill have been determined. The results obtained have been used to identify and verify the matrix grinding model. Within the framework of the resulting model, a method for technological calculation of a jet mill operating in an open grinding cycle has been developed. The presented approach allows us to propose the ways to develop and implement new jet grinding technologies to obtain highly pure products in open and closed grinding cycles.

Structure and Magnetic Properties of Iron Oxide Nanoparticles Subjected to Mechanical Treatment

Iron oxide nanoparticles have been fabricated using the electric wire explosion (EWE) technique. The structure and magnetic properties of the nanoparticles have been analyzed before and after mechanical grinding in a ball mill for different time periods, focusing on potential bioapplications. The phase composition of the nanoparticles (70% Fe3O4, 30% Fe2O3) has remained unchanged despite the mechanical effects. The average nanoparticle size has not been affected either. The observation of the Verwey transition in the studied nanoparticles, along with the structural data, provides a better understanding of the physical properties of EWE ensembles of nanoparticles in different states. The analysis of the structure and magnetic properties reveals the development of a material with a high level of internal stress. This finding may be of interest for bioapplications due to its potential impact on the material performance.

Magnetic Properties of a Nickel–Zinc Ferrite Powder with Different Degrees of Dispersion

The influence of the degree of dispersion of a nickel–zinc ferrite powder of a Ni0.7Zn0.3Fe2O4 composition on its magnetic properties has been considered. The material has been synthesized using the ceramic technology with preliminary mechanical activation of precursors. The degree of dispersion has been varied using different modes of its dry grinding in a ball mill. The patterns of the changes in saturation magnetization and the coercive force as a function of grinding modes and a specific surface area of the ferrite powder have been established. The changes in the pattern of the magnetic phase transition in the region of the Curie temperature of materials with different degrees of dispersion have been determined.

Advanced nano modification of ecofriendly glauconite clay for high efficiency methylene blue dye adsorption

This research focuses on the utilization of nano glauconite clay as an environmentally friendly sorbent for the removal of cationic dyes, particularly Methylene Blue (MB), from polluted water. The glauconite clay was sourced from the El Gidida region of Egypt and subjected to grinding in a laboratory-type ball mill to ensure homogeneity and increase the active sites available for the adsorption process. The resulting ball milled nano clay (BMNC) was characterized using techniques such as X-ray fluorescence (XRF), Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). The concentration of MB dye was monitored using UV–Vis spectroscopy to assess the adsorption capacity of BMNC under various conditions including pH, time, dose, and temperature. The optimal conditions for the adsorption process were determined to be a pH range of 7–8, a contact time of 60 min, and a dose of 200 ppm, resulting in an adsorption capacity of 128 mg/g. This process demonstrated both low cost and high speed. The adsorption mechanism of MB on the BMNC surface was evaluated through kinetics, adsorption isotherms, and thermodynamics. The experimental data indicated an endothermic, spontaneous, and thermodynamically favourable adsorption process, which was further supported by simulated modelling results using Forcite program. The in-silico data aligned well with the experimental findings. Additionally, the study assessed the interference of salts, metal ions, and other dyes on MB adsorption onto BMNC, showing promising results. These findings strongly support the effectiveness of our sorbent substrate under challenging conditions.

Innovative predictive maintenance for mining grinding mills: from LSTM-based vibration forecasting to pixel-based MFCC image and CNN

Innovative predictive maintenance for mining grinding mills: from LSTM-based vibration forecasting to pixel-based MFCC image and CNN

The influence of the weighted average diameter of the ball on the particle size of the final product

Objective. Currently, cement is crushed in mills to a specific surface area of 2500-3000 and 3500-4500 cm2/g or more. Further grinding of clinker sharply worsens the properties of the resulting product. The relevance of the topic is due to the increased interest in reducing material and energy costs in the process of clinker grinding. The purpose of the work is to study the effect of different assortment of grinding media and weighted average ball diameter on the particle size of the final product, performing particle size analysis by particle diffraction. Method. To obtain reliable experimental data, a specially developed model of the grinding unit was used. Analysis of particle size by diffraction or spatial distribution (scattering spectrum) of scattered light was carried out using a laser analyzer. Result. A research methodology has been developed that meets the modern capabilities of experimental technology. Experimental studies have been conducted on clinker grinding in a laboratory mill. The combined effect of different assortments of grinding bodies and the average weighted diameter of the ball on the particle size of the final product has been determined. Conclusion. Studies of the curves of the final product obtained using different weighted average ball diameters have shown that large impact energy is not required to grind small grains; the diameter of the grinding bodies should decrease as the grain size of the material decreases. Therefore, the balls must have a minimum diameter, but sufficient to destroy the particles of the material.

Effects of clay grains on the shear properties of unsaturated loess and microscopic mechanism

Different clay grains affect the structural strength of loess through the cementation of skeletal particles. This study investigates both clay-clay grains and quartz-clay grains. Clay-clay grains mixed loess (CM-L) and quartz-clay grains loess (Q-L) samples were prepared, and their unsaturated shear properties analyzed. X-ray diffractometry (XRD) analysis was conducted to determine the types and proportions of clay grains. Ball mill grinding and laser particle size analysis were employed to ensure comparable sizes of clay grains, while mercury intrusion porosimetry (MIP) tests confirmed similar pore characteristics. Scanning electron microscope (SEM) and unsaturated triaxial consolidation and drainage tests explored the impact of different clay grains on loess shear characteristics, assessing both microscopic and macroscopic performance. The results indicate that CM-L loess exhibits higher cohesion and a lower internal friction angle at the same matric suction level. The cohesion and internal friction angle of both CM-L and Q-L loess exhibit a linear relationship within the range of 50–200 kPa matrix suction. The cohesive force ranges for CM-L and Q-L loess are 60.31–80.07 kPa and 43.01–69.60 kPa, respectively, while the ranges for internal friction angles are 19.95°-19.59° and 25.91°-25.06°, respectively. Compared to Q-L loess, CM-L loess exhibits an average difference in cohesion of 23.18 kPa and in internal friction angle of -5.72°. The microscopic variation in shear strength can be attributed to the “fish scale-like” interlocking state between clay-clay grains and the “tower-like” scattering arrangement of quartz-clay grains. In conclusion, the effect of different clay-grain types on the shear strength of loess varies significantly. The present study elucidates the relationship between the influence of different clay grains on the mechanical properties of loess and their microscopic structural characteristics, thereby providing crucial data for investigating the microscopic effects on the structural strength of loess.

Effect of Grinding Media Grading on Liner Wear and Load Behavior in a Ball Mill by Using Rocky DEM

The liner is a wear-prone component in ball mills, subject to continuous impacts, squeezing, and abrasion from the grinding media during operation. Its service performance directly affects the working efficiency of the ball mill. The service life of mining ball mill liners is about 8 months, and frequent downtimes occur due to liner wear and loss of effectiveness, with liner replacement accounting for about 6% of the total cost, resulting in huge economic losses. This paper focuses on a Φ305 mm × 150 mm experimental ball mill, using the discrete element software Rocky Discrete Element Method (DEM) (software version number Rocky 2022 R2) for simulation modeling analysis. With Φ10 mm and Φ20 mm mono-size particle simulations serving as reference groups, this study investigates the motion states and liner abrasion patterns under different liner heights for both sizes of grinding media in Equilibrium Quality Manufacturer (EQM) and Original Equipment Manufacturer (OEM) gradations. The results indicate that the impact of liner height on the wear of the ball mill liners is related to the size and gradation of the grinding media. The degree of liner wear from highest to lowest is as follows: EQM > Φ20 mm > OEM > Φ10 mm. Due to the effect of the cylinder end cap, the wear at the axial center of the ball mill liner is more severe than at both ends, and the wear on the facing side of the liner is more severe than on the backside. A thorough study of the influence of ball mill grinding media gradation on the wear pattern of liners is of great theoretical significance for optimizing liner structures, improving grinding efficiency, and promoting energy saving and cost reduction in ball mills. This study provides theoretical guidance for understanding the mechanisms behind liner wear in ball mills and predicting the liner lifespan.

Manifesting the Dasatinib-gallic acid co-amorphous system to augment anticancer potential: Physicochemical characterization, in silico molecular simulation, ex vivo permeability, and in vitro efficacy

Dasatinib (DAB) has been explored for repurposing in the treatment of breast cancer (BC) due to its known effectiveness in treating leukemia, in addition to its role as a tyrosine kinase inhibitor. Gallic acid (GA) was chosen as a co-former due to its anticancer potential in BC, as demonstrated in several previous studies. DAB is a low-solubility drug, which is a significant hurdle for its oral bioavailability. To address this limitation, a DAB and GA co-amorphous (DAB-GA-CA) system was developed using liquid-assisted grinding and ball mill technology to enhance solubility, bioavailability, and anti-tumor efficacy. Physical characterization investigation revealed that the emergence of the halo diffractogram in PXRD, single glass transition temperature (Tg) value at 111.7 °C in DSC thermogram, and irregularly shaped blocks with loose, porous surfaces in SEM analysis indicated the formation of the DAB-GA-CA system at 1:1 M ratio. Furthermore, FTIR, Raman spectroscopy, in-silico molecular docking, and molecular dynamic studies confirmed the intermolecular hydrogen connections between DAB and GA. Moreover, the outcomes of the ligands (DAB and GA) and receptors (BCL-2, mTOR, estrogen receptor, and HER-2) docking studies demonstrated that both DAB and GA could interact with those receptors, leading to preventive action on BC cells. Additionally, the solubility and dissolution rate significantly improved at pH 6.8, and the permeability study indicated that DAB-GA-CA showed 1.9 times higher apparent permeability compared to crystalline DAB. Furthermore, in vitro cytotoxicity assessments of the DAB-GA-CA system revealed 3.42 times lower IC50 than free DAB. The mitochondrial membrane depolarization, apoptotic index, and reactive oxygen species formation in MCF-7 cells were also notably higher in the DAB-GA-CA system than in free DAB. Hence, this research suggests that the DAB-GA-CA system could substantially enhance oral delivery, solubility, and therapeutic efficacy.

Ball-Milling Enhanced UV Protection Performance of Ca2Fe-Sulisobenzone Layered Double Hydroxide Organic Clay.

Using a co-precipitation technique, the anionic form of sulisobenzone (benzophenone-4) sunscreen ingredient was incorporated into the interlayer space of CaFe-hydrocalumite for the first time. Using detailed post-synthetic millings of the photoprotective nanocomposite obtained, we aimed to study the mechanochemical effects on complex, hybridized layered double hydroxides (LDHs). Various physicochemical properties of the ground and the intact LDHs were compared by powder X-ray diffractometry, N2 adsorption-desorption, UV-Vis diffuse reflectance, infrared and Raman spectroscopy, scanning electron microscopy and thermogravimetric measurements. The data showed significant structural and morphological deformations, surface and textural changes and multifarious thermal behavior. The most interesting development was the change in the optical properties of organic LDHs; the milling significantly improved the UV light blocking ability, especially around 320 nm. Spectroscopic results verified that this could be explained by a modification in interaction between the LDH layers and the sulisobenzone anions, through modulated π-π conjugation and light absorption of benzene rings. In addition to the vibrating mill often used in the laboratory, the photoprotection reinforcement can also be induced by the drum mill grinding system commonly applied in industry.

The effects of processing parameters on the shape of particle size distribution and grinding rate in a stirred mill

The study of particle size distribution (PSD) of materials is a crucial aspect of mineral processing. It not only determines the appropriate beneficiation process and equipment but also has a significant impact on the grade and recovery of concentrate. This study utilizes a pin-stirred mill for the wet fine grinding of limonite to examine four different widths of PSD functions and compares their quantitative descriptions of the PSD. Skewness is a parameter introduced to quantitatively describe the asymmetry of the PSD. This study aims to investigate the effect of the stirrer speed, the density and the size of the grinding media on the shape of the PSD and on the grinding rate. The results show that a lower stirrer speed and a lower density of the grinding media result in a narrower and a more symmetrical PSD of the grinding products. Moreover, the time-dependent approach succeeds in simulating and proving the evolution behavior of the median particle size. It was found that the optimum mixing ratio of the grinding media can effectively adjust the shape of the PSD and improve the grinding efficiency.

Synergic effects of silica aerogel (SA) particles on tensile behavior of cryo-conditioned epoxy: The role of particle morphology and mixing sequence

Cryogenic conditions are of crucial importance for gas storage tanks to provide increased storage density, reduced pressure requirements and minimized energy losses. Incorporation of silica aerogel (SA) particles as a nanostructured material with extremely low density and exceptional thermal insulating properties into epoxy matrices has the potential to facilitate the progress of high performance nanocomposite coatings for advanced cryogenic applications. The objective of this study is therefore to investigate the impacts of particle size, particle content, milling method and mixing sequence on toughness of the cryo-conditioned epoxy coatings. SA particles of varying size (50 μm to 300 μm) were prepared using two different techniques (planetary ball milling vs. 2-blade grinding). Nanocomposite samples were prepared using two distinct mixing sequences, i.e., adding particles (in 0, 0.5, 1 and 1.5%wt.) to epoxy followed by mixing with hardener or adding particles to epoxy/hardener (with 3 or 15 min delay). The nanocomposite samples were subjected to different cryogenic conditions (single 3-h immersion in liquid nitrogen vs. three consecutive 1-h immersions). Mechanical properties of the samples were evaluated by conducting fractography, dynamic mechanical thermal analysis (DMTA) and tensile tests. Large SA particles settled towards the bottom of nanocomposite and resulted in loss of mechanical properties at cryo-conditions. Mixing 1 wt% of optimized SA particles with epoxy/hardener system led to an enhanced tensile strength (26 %), stiffness (3 %) and toughness (71 %) by providing uniform cross-linking reactions and mitigating thermal shock effects at cryo-conditions. Toughening mechanisms included crack deflection, crack pinning, crack arrest and crack branching.

Heterarchical modelling of comminution for rotary mills: part II—particle crushing with segregation and mixing

In granular media, the crushing of individual particles is influenced by the number of contacts with neighbouring particles. This well-known phenomenon of “cushioning” shields the individual particles from crushing when the number of contacts is high. However, in open systems that involve extensive granular flow and bulk motion, like those found in industrial mills, the neighbouring particles continually exchange positions due to segregation and mixing, thereby altering the number of neighbouring contacts and their sizes, affecting the crushing of individual particles. Therefore, a critical challenge for properly modelling comminution in such systems lies in tracking the fluxes of the various particle size classes. Here, we explore the physics that governs the mechanisms of segregation and mixing within the multiscale heterarchical modelling paradigm. Building upon the framework developed in Part I, which integrated the heterarchical aspects of the physics of crushing along streamlines, we further account for segregation and mixing, and demonstrate their impact on the comminution efficiency of autogenous grinding mills. In particular, segregation is shown to greatly enhance the extent of particle crushing within the mill. Accordingly, we posit that this mechanism cannot be ignored. In summary, the new model sheds light on previously obscured dynamics within industrial mills, as well as enables the field to predict the time evolution of the particle size distribution at any point in the mill domain. This modelling capability opens the doors to new developments for estimating and improving milling efficiencies.Graphical

Heterarchical modelling of comminution for rotary mills: part I—particle crushing along streamlines

Rotary mills aim to effectively reduce the size of particles through a process called comminution. Modelling comminution in rotary mills is a challenging task due to substantial material deformation and the intricate interplay of particle kinematics of segregation, mixing, crushing, and abrasion. Existing particle-based simulations tend to provide predictions that cannot cope with the large number of particles within rotary mills, their wide range of sizes, and the physics dictating the crushing of individual particles. Similarly, there is currently no deterministic modelling means to determine the evolving population of particle sizes at any point in time and space within the mill. The aim of this two-part contribution is to address these gaps by advancing a framework for a novel stochastic comminution model for rotary mills, which has a well-defined deterministic continuum limit and can cope with arbitrarily large numbers of particles. This work describes the basic physics and structure of the new model within a heterarchical framework for ball and autogenous grinding mills. The primary focus of this Part I paper is to develop a computational model for the integration of motion of material along streamlines inside a mill. Coupled to this process is the kinetic physics dictating particle crushing. In a subsequent work, Part II, segregation and mixing will be added to this model such that realistic behaviour from the mill can be observed.Graphical

Failure Analysis of Pulverized Coal Injection (PCI) Mill Grinding Roller Bearing at Blast Furnace

Failure Analysis of Pulverized Coal Injection (PCI) Mill Grinding Roller Bearing at Blast Furnace

Prediction method of particle size qualification rate of high-pressure roller mill based on end-edge-cloud synergy

The pass rate of granules is an essential indicator during the high-pressure grinding process, as it accurately reflects the processing quality. Currently, the pass rate of granules is detected primarily based on manual experience judgments or offline inspections. Hence, this article presents a methodology for predicting the pass rate of granularity via an optimized support vector regression approach improved through genetic algorithms. Initially, a time-delay analysis method based on the particle swarm optimization algorithm is applied to mitigate the effects of time delays between the granularity pass rate and other data, thus aligning the dataset on a temporal scale. Subsequently, the feature data were selected using the maximum information coefficient analysis technique, which identified the most significant variables for inclusion in the training and testing sets of the predictive model. Predictions are then made using a support vector machine model that has been enhanced via genetic algorithm optimization. Furthermore, an online prediction model has been established, enabling real-time forecasting of the granularity pass rate and online model updates through root mean square propagation gradient descent optimization algorithm. This method leverages end-edge-cloud collaboration to provide a smart detection mechanism for the throughput rate of particles in high-pressure grinding mills. Experimental results demonstrate that, compared to traditional time-delay analysis, the improved time-delay analysis method proposed in this study is more effective and accurate. Simultaneously, the ɛ-GASVR granularity pass-rate prediction model proposed in this article achieved an R2 of 0.89.

Investigating Dynamic Behavior in SAG Mill Pebble Recycling Circuits: A Simulation Approach

The dynamics of milling circuits, particularly those involving Semi-Autogenous Grinding (SAG) mills, are not adequately studied, despite their critical importance in mineral processing. This paper aims to investigate the dynamic behavior of an SAG mill pebble recycling circuit under varying feed ore conditions, focusing on both uncontrollable parameters (such as ore hardness) and controllable parameters (including circuit layout and pebble crusher configurations). The study is carried out with Simulink dynamic simulations. Our findings reveal several key insights. Firstly, plant designs based solely on static simulations may not be adequate for large or complex circuits, as they fail to account for the dynamic nature of milling processes. Second, incorporating stockpiles after pebble crushing can effectively mitigate the impact of dynamic fluctuations, leading to more stable circuit performance. Third, different circuit layouts can facilitate easier maintenance and operational flexibility. Notably, finer pebble crushing can enhance circuit throughput by 5% to 10%.

The effect of functional lipids on the quality of walnut butter prepared from defatted walnut meal by ball mill grinding

AbstractIn this study, walnut butter was produced by mixing functional lipids with defatted walnut meal. Three kinds of functional lipids (FL), medium‐chain triglycerides (MCT), diacylglycerol (DG), and conjugated linoleic acid glycerides (CLA), were used to make functional lipids walnut butter (DG‐WB, CLA‐WB and MCT‐WB) and their physical properties as well as microscopic morphology were compared with commercial walnut butter. The functional lipids walnut butter (FLWB) was prepared by grinding FL and defatted walnut meal through the ball milling technique. The mixing ratios of FL to defatted walnut meal were 6:4, 6.5:3.5, and 7:3. The volumetric mean particle size of emulsion formed by DG‐WB and CLA‐WB decreased by 36.23% and 20.88%, respectively when the additional amounts of DG, and CLA increased from 60 wt% to 70 wt%. The rheological and microrheological results further indicated that FLWB showed similar gel‐like behavior to commercial walnut butter. Among the FLWB with three different kinds of FL, CLA‐WB appeared more similar apparent viscosity, thixotropy, and elasticity with those of commercial walnut butter. Finally, CLA‐WB with different CLA additive amount was analyzed for microstructure. The results showed that walnut butter prepared with 65 wt% CLA was closer to commercial walnut butter in terms of processed physical properties and micro‐morphology.