Crushing Process Research Articles

RETRACTED: Zhong et al. Fractal Behavior of Particle Size Distribution in the Rare Earth Tailings Crushing Process under High Stress Condition. Appl. Sci. 2018, 8, 1058

The Applied Sciences Editorial office retracts the article “Fractal Behavior of Particle Size Distribution in the Rare Earth Tailings Crushing Process under High Stress Condition” [...]

Application of design of experiments (DoE) in evaluating crushing-screening performance for aggregates production

The configuration and the interaction between the crushers and screens enable aggregate producers to produce products that are in accordance with the applicable product certification. However, the performance of the system is seldom optimized for the given conditions and market demand. This paper aims to describe the experimental work and the results of quantifying the crusher and screen performance by applying the design of experiments (DoE) in a full-scale tertiary crushing process of an aggregate production plant with both standard belt-cut sampling as well with continuous processes monitoring. The results show the application of a simplified modelling approach using the design of experiments for the evaluation of crusher performance and circuit performance using experimental data. The research output is able to demonstrate that there exists an interaction effect between the crusher closed side setting and eccentric speed that previously has not been identified with traditional methods. The quantification of interaction between crusher and screen individual performance to the process performance has been demonstrated with both belt-cut samples and continuous process monitoring. Using a DoE, digital experiments can be planned for mapping and quantifying the performance of aggregate production.

Bond Parameter Calibration and Crushing Process Analysis of Brown Rice Kernels

Aiming to resolve the practical problem of brown rice kernels being easily broken due to overprocessing during processing (milling and polishing), brown rice kernels of Japonica rice, after hulling, were used as the research object in this study. Firstly, through a texture meter test, the discrete element bonding parameters (Kn is normal stiffness per unit area, Kτ is tangential stiffness per unit area, Cn is critical normal stiffness, Cτ is critical shear stiffness) were obtained. Secondly, a brown rice kernels’ bonding particle model was established by EDEM, and then a second orthogonal rotational combination test was carried out to calibrate the discrete bonding parameters, Kn = 4.43 × 1012 N/m3, Kτ = 6.13 × 1011 N/m3, Cn = 2.55 × 107 Pa, and Cτ = 7.92 × 107 Pa. The error of parameter calibration was within 5%, and the results were able to reflect the actual situation more realistically. Finally, analysis of the crushing process of brown rice kernels showed that their ability to withstand shear damage was not as great as their pressure-bearing capacity. The design of the relevant mechanism and the setting of parameters should be based on the critical shear stiffness of brown rice kernels, and the actual shear force Fτ* set during the processing should be smaller than the theoretical critical shear force Fτ (Fτ* < Fτ = 9.11 N). This study can provide a theoretical basis for optimizing the key structure and operating parameters of rice milling machines and polishing machines to effectively solve the practical problem of increased crushing of brown rice kernels due to overprocessing.

Modelling the Rheology of Olive Paste for Oil Extraction Plant Automation: Effects of the Crushing Process on the Rheology of Olive Pastes.

In extra virgin olive oil production, it is essential to obtain a well-prepared olive paste which allows not only the extraction of the oil drops from the olives, but also the achievement of a high-quality oil while maintaining high yields. This work addresses the problem of determining the effect of three crushing machines on the viscosity of the olive paste: a hammer crusher, a disk crusher and a de-stoner were tested. The tests were repeated on both the paste leaving each machine and the paste to which water was added; this was done with the main aim of considering the different dilutions of the paste while entering the decanter. A power law and the Zhang and Evans model were used to analyse the rheological behaviour of the paste. The experimental results allow validation of the two models with a high (more than 0.9) coefficient of determination between experimental and numerical data. The results also show that the pastes obtained with the two classic crushing methods (hammers and disks) are almost identical, with a packing factor of about 17.9% and 18.6%, respectively. Conversely, the paste obtained with the de-stoner entails higher viscosity values and a smaller solid packing factor, of about 2.8%. At 30% dilution with water, the volume of the solid concentration dropped to about 11.6% for the hammer and disc crushers, while for the de-stoner it only reached 1.8%. This behaviour is also reflected in the evaluation of yields, which were 6% lower with the de-stoner. No significant differences regarding the legal parameters of oil quality were found using the three different crushing systems. Finally, this paper establishes some fundamental pillars in the research for an optimal model for identifying the rheological behaviour of the paste as a function of the crusher used. Indeed, since there is an increasing need for automation in the oil extraction process, these models can be of great help in optimizing this process.

Mechanism of Phase-Locked Ice Crushing against Offshore Structures

This paper addresses a detailed analysis of the ice–structure interaction process of the phase-locked ice crushing (PLC) against offshore structures. Directly measured ice load, structure response data, and in situ observation from the field measurements on the Molikpaq lighthouse and jacket platform were used in the study. This paper summarizes a new ductile damage-collapse (DDC) failure mechanism for the PLC process. The DDC mechanism shows that the ice failure is a discrete ductile crushing process rather than a ductile–brittle transition process. The analysis identifies that the ice has a failure length in PLC and this failure length plays an important role in understanding the interaction. It reveals that PLC can occur on most vertical-sided offshore structures when the velocity of the ice sheet falls within the range of the failure length divided by the natural period of the structure. This paper proposes that this relationship between ice failure length and the natural period of the structure can be used as one of the PLC occurrence conditions. The DDC failure mechanism provides a basis for another technical route to solve the PLC problem.

Manufacture of Geopolymer Artificial Aggregates by Pelletization and Crushing Processes

Aggregates are an important ingredient of concrete. They are of two types: coarse aggregates and fine aggregates. The supply of natural aggregates on Earth is declining with technological advancement, hence, alternatives to natural aggregates are needed. Artificial aggregates have been manufactured using a coal burning waste, i.e. fly ash. On mixing fly ash with an alkaline activator, the mixture reacts and hardens. Aggregates are manufactured either by mixing materials using a granulator pan or by crushing materials using a stone crusher. The optimal manufacturing method was determined by comparing physical properties, such as bulk specific gravity, water absorption, and aggregate hardness, of the aggregates manufactured using these two methods with those of natural coarse aggregates. The average bulk specific gravity was 1.776 and 1.857 for the aggregates produced by the pelletization and crushing processes, respectively, and 2.957 for the natural aggregates. The average water absorption values were 11.62% and 8.37% for the aggregates produced by the pelletization and crushing processes, respectively, and 4.17% for the natural aggregates. The average aggregate hardness values, determined using the Los Angeles abrasion test, were 27.33% and 25.98% for aggregates produced by the pelletization and crushing processes, respectively, and 24.05% for the natural aggregates.

Study on the Influence of the Mechanical Crushing Process on Low-Temperature Oxidation Characteristics of Coal Samples

ABSTRACT In order to study the influence of the mechanical crushing process on the low-temperature oxidation characteristics of coal, the programmed heating experiments of coal samples with different particle sizes were carried out using a programmed heating device. By comparing and analyzing the changes in CO and CO2 emission, cross-point temperature, heat release intensity, and apparent activation energy of coal samples with different particle sizes during temperature heating, the influence of particle sizes on the spontaneous combustion characteristics of coal samples was obtained. On the basis of the infrared spectrum experiment and ESR (electron paramagnetic resonance) experiment of coal samples with different particle sizes, the changes of functional groups and free radicals were further compared, and the deep-seated reasons that the mechanical crushing process affected the spontaneous combustion characteristics of coal were explored. The results showed that with the decrease in particle size, more alkyl side chains are dehydrogenated to produce alkyl radicals during mechanical crushing, and the alkyl radicals are oxidized with oxygen to form more oxygen-containing functional groups. These oxygen-containing functional groups can accelerate the low-temperature oxidation process of coal in the subsequent secondary low-temperature oxidation process, release more heat, and increase the heat release intensity. In the process of mechanical crushing, the coal sample not only changes in physical structure but also changes in chemical structure. With the decrease in particle size of coal samples, more CO and CO2 are produced in the process of low-temperature oxidation of coal, and the time to reach the cross-point temperature is advanced. However, the cross-point temperature and the apparent activation energy decreases, and the spontaneous combustion characteristics of coal are enhanced.

Study of the Energy-Power Parameters of the Crushing Process in Hammer Crushers

Study of the Energy-Power Parameters of the Crushing Process in Hammer Crushers

Experimental Investigation of Particle Size Alteration and the Selective Crushing Phenomenon of Gangue during the Jaw Crushing Process

This study examines the particle size and distribution of the main chemical components of gangue during the crushing process. Coal mine gangue was chosen as the research object, and its particle size and chemical components at various crusher discharge settings were examined through screening, grinding, chemical composition testing, and other methods. The findings demonstrate that the characteristic particle size in the gangue particle size distribution model has a logarithmic upward trend as the width of the discharge port increases. In contrast, the uniformity index has shown an exponential downward trend. The analysis of the distribution rate and enrichment ratio of the main chemical components of the gangue at different widths of the discharge port shows that the gangue exhibits obvious selective crushing during the crushing process. The distribution rate of each component is affected by the size of the screen aperture to various extents. As the discharge port width increases, the elements of CaO and MgO are enriched in the coarse-grained products, while those containing Fe2O3 are enriched from fine-grained to coarse-grained. Gangue particles containing Al2O3, SiO2, and C are enriched in the fine-grained product. In addition, by analyzing the alterations in the main chemical components of gangue at different particle size intervals, it was found that the amount of each component first rises and then falls, and the trend of enrichment ratio to particle size follows an exponential pattern. The research results have significance for guiding the selection of resource utilization methods of gangue with different particle sizes after crushing.

Modeling Technology of Bonded Particle Model for Gold Ore and Its Validation Based on Drop Weight Test

In recent years, studies have focused mainly on the selection of appropriate parameters for ore crushing technology to achieve optimal distributions of particle sizes. The control of particle sizes in mineral processing plays a significant role in improving mineral separation efficiency. The discrete element method (DEM) is an effective numerical simulation method for studying the process of mineral crushing, which can deal with the problem of deformation and movement of discontinuities, that is, the problem of cracks caused by mineral crushing, which is difficult to be solved by traditional continuum mechanics simulation methods. Additionally, the transformation of a mechanical model from continuum to discontinuum mechanics can be realized simply and effectively, so the discrete element method has obvious advantages in the simulation of mineral crushing. However, the accuracy of the DEM simulation is highly dependent on the mathematical models used. In this paper, methodologies for selecting particle sizes and inter-particle bond energy are proposed based on the results of the drop weight test carried out in the laboratory. Particle sizes and inter-particle bond energy are the key parameters for bonded particle model used in discrete element simulation. The suitable parameters proposed by methodologies were applied to construct the bonded particle model for the ore, and its particle size distribution was obtained by simulating the impact crushing process using DEM. The particle size distributions obtained from both the DEM simulation and the drop weight test were in good agreement. The average errors under the three impact energies were 1.96%, 3.31%, and 1.66%, which indicated that the modeling technique proposed in this paper can represent the crushing characteristics of ore materials and improve the accuracy of the DEM simulation. It lays the foundation for guiding the reasonable selection of grinding process parameters and mill equipment.

Simulation of Electrical and Thermal Properties of Granite under the Application of Electrical Pulses Using Equivalent Circuit Models.

Since energy efficiency in comminution of ores is as small as 1% using a mechanical crushing process, it is highly demanded to improve its efficiency. Using electrical impulses to selectively liberate valuable minerals from ores can be a solution of this problem. In this work, we developed a simulation method using equivalent circuits of granite to better understand the crushing process with high-voltage (HV) electrical pulses. From our simulation works, we calculated the electric field distributions in granite when an electrical pulse was applied. We also calculated other associated electrical phenomena such as produced heat and temperature changes from the simulation results. A decrease in the electric field was observed in the plagioclase with high electrical conductivity and void space. This suggests that the void volume in each mineral is important in calculating the electrical properties. Our equivalent circuit models considering both the electrical conductivity and dielectric constant of a granite can more accurately represent the electrical properties of granite under HV electric pulse application. These results will help us better understand the liberation of minerals from granite by electric pulse application.

Effects of recovered brown alumina filler loading on mechanical, hygrothermal and thermal properties of glass fiber–reinforced epoxy polymer composite

This study investigates the efficiency of recovered brown alumina (RBA) particles filled in epoxy glass-fiber composites. The RBA particles were obtained from grinding wheel rejects with the help of the mechanical crushing process. Recovered particles finer than 120 grit were used as particulate filler for composite preparation. Composites were processed through a hand-layup technique by varying RBA filler loading percentages (0, 5, 10, 15, and 20 wt.%) in a glass fiber–reinforced epoxy matrix. Physical, mechanical, water absorption, and thermal properties of the composites were tested experimentally. By suitable addition of RBA, it is possible to tailor the shore-D hardness, tensile modulus, flexural strength, flexural modulus, and maximum degradation temperature. The 20%-filled RBA composite shows the maximum flexural strength of 382 MPa, and the shore-D hardness value was 85. The fracture surface shows a failure mechanism dominated by matrix cracking and debonding of fiber/particles from the interface. Hygrothermal testing of the RBA20-filled composite reveals 9% and 4% reduction in tensile and flexural properties. The thermal stability of the glass fiber–reinforced composite improves as the filler percentage increases. Maximum thermal stability of 435°C was observed in 20%-filled RBA polymer composite.

Influence of Natural Aggregate Crushing Process on Crushing Strength Index

Crushing is one of the most energy-consuming technological processes. The purpose of grinding is to achieve the desired grain size of mineral raw materials. The process of grinding consists of many factors, for example, the size and form of crushed grains, as well as their mutual arrangement inside the crushing machine chamber, the technological parameters of the crusher, the material properties, and the speed of the moving grains. One of the key parameters of the aggregate is its resistance to grinding. Resistance to grinding is related to the strength of the products made from aggregates subjected to grinding, which affects the overall quality of these products. Therefore, the aim of this study is to analyze the impact of the crushing of natural aggregate on the LA crumbling strength index. Two types of aggregates were analyzed—natural gravel and natural pebbles crushed in a crusher. Aggregates were acquired from two mines belonging to the plant Kruszgeo S.A. in Rzeszów, i.e., ZEK (Zakład Eksploatacji Kruszywa) Ostrów and ZEK Strzegocice II. The aggregate crushing process was carried out for 4–8 mm and 10–14 mm fractions using cone crushers of the 1044 type. Aggregate crushing was carried out in a Los Angeles drum, in accordance with the requirements of EN 1097-2:2020. The analysis showed that for grits of the 10–14 mm fraction, the lower values of the LA indices were obtained, which allows for obtaining a bigger index of crushing strength than in the case of crushing using the 4–8 mm fraction. This analysis showed how important the process of grinding aggregates is and, thus, the appropriate selection of fractions for the grit crushing process for the aggregate strength on grinding. Subjecting the aggregate to the grinding process results in an improvement in the crushing strength indicator, thus obtaining better strength parameters of the products manufactured from the aggregates subjected to the process of crushing (for example, concrete). The originality of the study is an analysis of key Polish aggregates and the crushing strength index.

Effect of Multi-Walled Carbon Nano tubes on the Quasi-Static Lateral Crushing Characteristics of Hybrid Glass-Basalt Fabric Reinforced Epoxy Tubes

Nano composite cylindrical tubular elements could be considerably employed as energy mitigating components for dissipating the impact energy during vehicular collisions. The current research work aimed to explore the lateral crashworthiness response of Multi-Walled Carbon Nano Tubes (MWCNT) filled epoxy composite (basalt and glass fabric) tubes of three different inner diameters using quasi-static compression. Final deformed shapes and crush force vs. deformation curves of all the recommended typical tube sections are calculated and discussed elaborately. The conclusions obtained exposed that better crashworthiness features of MWCNT reinforced epoxy composite tubes with a larger diameter, were owing to the favourable deformation styles occurring during lateral crushing process. Furthermore, the suggested hybrid composite cylindrical tubes with nano-fillers might be applied as energy dissipating components in modern vehicles.

On the Energy Absorption Capability of Metallic Tubes Subjected to the Radial Wall Crushing Process

Metallic tubes, under axial loading, are frequently preferred in many different industries due to their high energy absorption efficiency. The studies to increase the energy absorption capacity (EAC) of these structures are still up to date. In this study, the deformation behavior and EAC of regionally pre-deformed identical aluminum and steel tubes under axial loading were investigated experimentally. Regional strength increase in tubes was obtained by the radial wall crushing (RWC) process. The RWC process is carried out by radially crushing the desired areas of the metallic tube from the outside with the aid of a specially designed device. Strengthening (hardening) occurs in the pre-deformed regions and as a result, the EAC of the metallic tubes can be increased. It is also noteworthy that the increase in absorbed energy is provided without reinforcement materials. When the experimental results were examined, it was seen that the RWC increased the energy absorption value of aluminum and steel tubes approximately 23% and by 33%, respectively. In addition to energy increases, the folding beginning of the metallic tubes can also be directed by using the RWC process.

Analytical and Experimental Analyses on Corn Stalk Crushing Process

Analytical and Experimental Analyses on Corn Stalk Crushing Process

Experimental Study on the Pore Shape Damage of Shale Samples during the Crushing Process

Using crushed shale samples to obtain pore information from the gas adsorption experiments is a widely used method. Previous studies have evaluated the impact of the particle size on the pore size ...

On optimal control of the crushing process

In industry, in most cases, high grinding steppes are required. The automatic control of solid particulate material crushing is a prerequisite for maximizing equipment productivity. A more voluminous task, which must be solved in the automation of crushers, is related to the optimization of the entire process of multi-stage crushing, the effect of using separate units taking into account the requirements of automatic control, rather than by increasing the number of controlled parameters, allowing, as is often the case in practice, not only receive comprehensive information about the process, but also insure against possible malfunctions in the operation of unreliable devices. An automatic crusher performance control system control circuit has been developed. The following tasks are solved: construction and description of functional diagram of automatic crusher performance control system; defined mathematical and computer models of the automatic control system; optimal control scheme is defined.

A discrete element method model of corn stalk and its mechanical characteristic parameters

In a simulation model of the process of corn straw crushing, its physical parameters and the model itself influence the accuracy of the numerical calculations of the discrete element method. This study attempts to improve the simulation accuracy of the crushing process and to find the optimal combination of parameters. Based on the Hertz-Mindlin with Bonding contact model, multiple particle replacement and bonding programs written using Visual Studio were imported through the application programming interface (API) of a discrete element method (DEM) model to establish three particle-bonding materials for a numerical simulation of the crushing process. Using results of mechanical corn stalk tests, DEM simulations of impact fracture, compression fracture, and bending fracture were conducted to determine the optimal combination of parameters. The resultant DEM-parameter combination led to simulation errors of 3.83%, 5.95%, and 7.86% in numerical simulations of impact fracture, bending fracture, and compression fracture of corn stalks, respectively. The performance of the corn stalk DEM using the proposed optimal parameter combination was validated using a 9RS-60 corn stalk crusher, revealing that the numerical simulation error was 8.77%. This study can improve the accuracy of the discrete element method in the simulation of the corn straw breaking process.

Unveiling the Release Mechanism of Pollutants during the Crushing Process of Waste Printed Circuit Boards

Waste printed circuit boards (WPCBs) are hazardous wastes but also valuable resources. Mechanical crushing is widely used to recycle WPCBs. Some pollutants are released during the crushing, but the...