Optimum Grinding Research Articles

Optimization and Experimental Study of Iron Ore Grinding Medium Parameters Using EDEM Discrete Element Software.

Energy savings and consumption reduction of ball mills are crucial for industrial production. The grinding medium is an important component of a ball mill. In theory, using higher-density grinding media can yield better grinding results. However, for materials with varying grindability, employing grinding media of different densities can reduce energy consumption while maintaining the same grinding effect. This study simulates the motion of the grinding media in the mill using three different densities of balls and the same material (iron ore). The results reveal that balls with densities of 5.8 g/cm3 and 7.8 g/cm3 achieve faster grinding of materials into finer particles, but balls with a density of 5.8 g/cm3 consume less energy. Therefore, replacing a ball with a density of 5.8 g/cm3 in a ball mill can significantly reduce energy consumption. This study will assist in selecting the optimal grinding medium density for different materials, ultimately contributing to energy savings and reduced carbon emissions.

Experimental study on grinding process of Al-Mg2Si aluminum matrix composites

As an aluminum-based reinforcement, Mg2Si particles have excellent properties such as high hardness, high melting point, and high elastic modulus compared with other reinforcements and are widely used in aerospace and automobile fields. However, there is little research on the cutting mechanism of this material. In order to explore the surface grinding mechanism of Mg2Si/Al composites, Grinding simulation of low-volume fraction Mg2Si/Al composites was carried out by ABAQUS, and the influence of different positions of matrix and particle removal on the surface quality of Mg2Si/Al composites was expounded. The plane reverse grinding test was carried out by using CBN (boron nitride) grinding wheel. The L16(43) orthogonal test and three groups of single factor tests were designed. The orthogonal results show that the linear velocity of the grinding wheel has the greatest influence on the surface roughness, and the feed rate and grinding depth are significantly smaller. The range analysis shows that the optimal grinding parameters are: vs = 35 m/s, vw = 0.75 m/min, ap = 0.015 mm. The regression equation for surface roughness was established by using MATLAB. The single factor results show that the surface quality is obviously improved by increasing the linear velocity of the grinding wheel and reducing the feed rate and grinding depth through the observation of the morphology of the processed specimen. The analysis results show that defects such as pits, protrusions, burrs, and a small amount of fish-scale-like on the machined surface are mainly caused by the linear velocity of the grinding wheel, the pulling force of the grinding wheel, and the adhesion of the debris. The defects such as particle micro-cracks, particle pull-out, and matrix cracking on the subsurface, are mainly caused by the compressive stress of the grinding wheel and the stress concentration of the particles. The research results have guiding significance for future composite material cutting research and actual cutting processing.

Fine-grained concrete with the addition of highly dispersed brick scrap powder

The use of brick breakage in concretes and in binder compositions is a promising direction for the development of recycling ceramic bricks. The purpose of the present research was to evaluate the possibility of using mineral powders obtained from brick breakage as an effective dispersed component in the production of fine-grained concrete. In the work, mechanical grinding of ceramic raw material was carried out at different grinding times. It wasestablished that for brick-breakage powders, an increase in the grinding time does not lead to a proportional increase in the specific surface area of the powders.The maximum effective increase in the specific surface area of the obtained powders is fixed at a grinding duration of up to 5 minutes. Using differential thermal analysis, it is shown that crushed brick is not an active mineral additive, but can act as crystallization centers during the formation of hydrosilicates in the structure of composites. Samples of fine-grained concrete were produced, in which part of the cement was replaced with ceramic powders obtained at different grinding duration. It was determined that the replacement of cement in concrete mixtures with this highly dispersed additive in an amount of 20% (by weight), obtained at an optimal grinding time in a ball mill, does not lead to a change in the physico-chemical characteristics of the final concrete composite.

Preparation of Modified Polycarboxylate by Pyrrolidone for Using as a Dispersant in Cobalt Blue Nano-Pigment Slurry.

In this paper, N-vinylpyrrolidone was copolymerized with acrylic acid and itaconic acid by free radical polymerization, and a series of polyacrylic acid-co-itaconic acid-co-N-vinylpyrrolidone (PAIN) dispersants with different pyrrolidone ligand contents were synthesized and characterized. Then, the cobalt blue nano-pigment slurry (20 wt%) was prepared through a water-based grinding method, and the optimum grinding technology was explored and determined as follows: PAIN2 as a dispersant, a dispersant dosage of 10 wt%, and a grinding time of 480 min. According to this optimum grinding technology, the prepared pigment slurry had a significantly decreased agglomeration, the D90 of which was 82 nm, and separately increased to 130 nm and 150 nm after heat storage for 3 and 7 days, exhibiting excellent heat storage stability. Additionally, its TSI value was also the lowest (1.9%), indicating good dispersion stability. The QCM and adorption capacity measuring results showed PAIN2 had a larger adsorption capacity, and the formed adsorption layer had a higher rigidity and was not easy to fall off. This was caused by both the interaction of carboxyl groups and the pyrrolidone ligand (strong coordination interaction) in PAIN2 with cobalt blue. The XPS and FT-IR measurements further proved the above-mentioned adsorption mechanism.

Prediction model of grinding roughness for worm with complicated space tooth surface

Optimum grinding parameters are crucial for achieving high-quality grinding of helical tooth surfaces for worm drives. The complex coupling motion relationship and formation mechanism between the worm blank and the grinding head make it difficult to predict the effect of grinding parameters on tooth surface roughness. Therefore, we developed a prediction model for the worm tooth surface roughness under conjugate grinding and applied it to the Roller Enveloping Worm Reducer (REWR). The forming process of the theoretical worm tooth surface during the grinding process was modeled by using the conjugate meshing principle. Considering the plowing and cutting effects of grinding particles on the tooth surface at different design parameters, feed speeds, and rotational speeds of the grinding head, the roughness prediction equation was established based on the theory of the maximum depth of valley bottom. Through the coupling analysis of the theoretical tooth surface model and the roughness prediction model, the prediction of the worm tooth surface roughness is realized. Based on the validated model, the influences of grinding parameters on the worm tooth surface roughness of REWR were quantitatively discussed. This study is of great significance for optimizing process parameters in the grinding of complex spatial surface transmissions.

Effect of Grinding Conditions on Clinker Grinding Efficiency: Ball Size, Mill Rotation Speed, and Feed Rate

The production of cement, an essential material in civil engineering, requires a substantial energy input, with a significant portion of this energy consumed during the grinding stage. This study addresses the gap in the literature concerning the collective impact of key parameters, including ball size, feed rate, and mill speed, on grinding efficiency. Nine spherical balls, ranging from 15–65 mm, were utilized in six distinct distributions, alongside varying feed rates and mill speeds. ANOVA, Taguchi, and regression analyses were employed to explore their influence on grinding efficiency and cement properties. The findings revealed that ball size variation significantly affects grinding performance, with smaller diameter balls yielding higher efficiency due to increased abrasion and fine formation. Conversely, elevating mill speed generally diminishes grinding efficiency, particularly at speeds approaching 90% of the critical speed, impacting ball shoulder and foot angles. Moreover, increasing the feed rate affects the grinding performance differently based on ball distribution, with finer distributions experiencing adverse effects. Signal-to-noise ratios facilitated determining the optimal control factor levels to minimize energy consumption. Quadratic regression models exhibited strong predictive capabilities for energy consumption in grinding. Ultimately, the optimal grinding performance was achieved with Bond-type ball distribution No. 6, considering ball size, mill speed, and feed-rate interactions, albeit with considerations regarding grinding time and energy efficiency.

Research on the surface modification and microstructure evolution during gear profile grinding based on cellular automaton

The matrix structure of high-strength gears mainly comprises martensite with high stacking fault energy. The dominant mechanism of microstructure evolution in the surface layer during profile grinding is continuous dynamic recrystallization. However, the understanding of continuous dynamic recrystallization structure evolution during gear profile grinding remains limited. In this study, a predictive model based on cellular automaton for martensite structure evolution during gear profile grinding is proposed. Coupled with the finite element method, the microstructure evolution prediction of high-strength steel gears in profile grinding is conducted. The proposed model demonstrates good consistency with experimental data in calculating the proportion of low angle grain boundaries during grinding process. By combining experimental and theoretical prediction results, the mechanism of the influence of grinding depth on grain refinement in surface layer during gear profile grinding is elucidated. The dislocation density increases with the increase of grinding depth, leading to the generation and transformation of more subgrains. By analyzing the grain size and the proportion of subgrain boundaries, an optimal grinding depth threshold under dry grinding conditions is determined. This study provides valuable insights into the continuous dynamic recrystallization structure evolution during gear profile grinding process.

Effect of grinding media shape on the particle size distribution of UG2 ore using the response surface methodology central composite design

In this study, the effects of truncated ellipsoids and cubes on the particle size distribution of a UG2 ore were compared to the spheres using the response surface methodology for experimental design, modeling, and optimization. The response surface methodology demonstrated that it can be useful in optimizing grinding operations. It provides lenses to see and analyze the behavior of the ball filling, interstitial filling, and % solids parameters which are complex and interactive, and their effects on the production of the desired product (−75 µm) for different grinding media. Spherical grinding media outperformed truncated ellipsoids and cubes, producing the highest amount of the desired size class (82.58%), followed by 80.41% for truncated ellipsoids and 77.07% for cubes. Spheres also consumed the least power followed by cubes and lastly truncated ellipsoids. The differences in optimal grinding conditions were attributed to different contact mechanisms, surface area, and load behavior of the grinding media.

Effects of abrasive grain size of flexible body-armor-like abrasive tool (BAAT) on high-shear and low-pressure grinding for zirconia ceramics

Zirconia ceramics exhibit remarkable performance. However, the high hardness and brittleness poses enormous challenges for machining. This study is integrally focused on preparing a flexible body-armor-like abrasive tool (BAAT) with enhanced tangential-to-normal force ratio. The rheological characteristics of the BAAT abrasive system with different abrasive grain were investigated. A series of grinding tests were conducted on a precision grinding machine. The grinding performance of the BAAT with different abrasive grain sizes was examined. Surface roughness (Ra) variation and tangential-to-normal force ratio were analyzed, together with the investigation of the three-dimensional surface morphology and surface hydrophilicity. It was found that smaller abrasive grain sizes ultimately generated lower surface roughness values after grinding. Under the optimal grinding conditions, the surface roughness (Ra) of zirconia ceramics decreased from 102 nm to 1.7 nm after 5 grinding strokes (∼1 min). Meanwhile, uniform grinding textures were obtained.

An automated mineralogy derived criterion for clustering ore samples for mineral liberation studies

Correctly determining the optimal grinding size is crucial for mineral processors, yet it poses several challenges. Still popular among practitioners, the empirical determination of the grinding target involves time-consuming and resource-intensive laboratory routines employed for generating quality, recovery and energy curves from which the target size is set. This approach becomes even more challenging for mines with diverse ore textures, requiring extensive testing on numerous samples to accurately capture the behaviour of the entire ore body. Consequently, a more efficient experimental method is highly desirable. A solution for reducing the laboratory effort is clustering samples according to the mineral liberation characteristics. This paper introduces a novel multivariate criterion for statistical clustering of ore samples for mineral liberation studies, derived from SEM-based automated mineralogy data. The criterion considers three variables: two coefficients (named A and k) derived from the exponential correlation equation between degree of liberation and the top size of the size fraction, and the overall degree of liberation, both easily obtained from the liberation spectrum for a top size of 1 mm. The effectiveness of the proposed criterion has been experimentally demonstrated. It was concluded that the clustering process correctly grouped samples with similar mineral liberation characteristics. The clustering approach can be used to significantly reduce the laboratory effort on liberation studies involving a great number of samples of different types of ore. Although developed using iron ore samples, the criterion's theoretical basis suggests its potential for adaptation to other types of ore.

Research on the Grinding Process of Superhard Particles in the Fluidized Bed Opposed Jet Mill Based on the CFD-DEM Methodology

The process of superhard particle breakage in the grinding zone of the fluidized bed opposed jet mill is investigated using the CFD-DEM (computational fluid dynamics-discrete element method) coupling method with the Tavares UFRJ Breakage Model in the present study. The effects of structural and operational parameters, such as target plate structure, nozzle position, air inlet velocity, and feed rate, on the equipment stress distribution, airflow velocity, pressure field, particle velocity, and cumulative particle size distribution are thoroughly studied to determine the optimal structural and operational parameters. Experimental validation is conducted, including scanning electron microscope (SEM) observation of particle morphology and analysis of particle size distribution of ground product particles. The simulation results indicate that the wear rate of the structure without a target plate is lower than that of the structure with a target plate in the grinding central zone. Therefore, the structure without a target plate is chosen for further investigation. The cumulative particle size distribution after grinding is influenced by nozzle position, air inlet velocity, and feed rate. The particle D50 is positively correlated with nozzle spacing and feed rate, while it is negatively correlated with air inlet velocity. The optimal grinding effect is achieved when the distance between the nozzle and the center of the grinding zone ranges from 52.5 mm to 72.55 mm, the air inlet velocity is 950 m/s, and the feed rate is 10.5 g/s. Through experimental investigation, it has been observed that when the feed rate is 10 g/s, the particle size distribution becomes more uniform. Furthermore, consistent trends in the cumulative particle size distribution in the experiment and simulation results can be found, which validates the present numerical model. It was observed that particles at low feed rates retain certain angular edges, while particle roundness increases at high feed rates.

Preparation and performance of 10 wt% of chlorantraniliprole Nano-suspension concentrate (SC) using polyether amine-bridged sulfonated alkali lignin (PSAL) as a dispersant

Polyether amine-bridged sulfonated alkali lignin (PSAL) with different sulfonic group contents and molecular weights was firstly synthesized and characterized. Then, 10 wt% of chlorantraniliprole Nano-suspension concentrate (SC) was prepared by the water-based grinding method, and the optimum grinding parameters were explored and obtained. Based on this optimum grinding formula, chlorantraniliprole Nano-SC was prepared and three optimum dispersants were finally obtained as follows: the compounds of polycarboxylate D-2 separately with P1SAL0.68, P1SAL0.84 and TERSPERSE 2500 at the mass ratio of 1:1. All Nano-SC prepared by these three dispersants had a D90 particle size below 200 nm, suspension percentage above 99%, water separation proportion below 1%, excellent thermal storage stability, and also better wettability on banana leaf surface. Additionally, adding glycerin could effectively inhibit the agglomeration and austenogenization of pesticide nanoparticles, and thus improve the stability of Nano-SC. Finally, the farmland experiments indicated chlorantraniliprole Nano-SC prepared in this work had a significantly improved pesticide effect on first-instar rice leaf rollers than traditional micron-sized SC. This work provided a new dispersant with excellent performance for chlorantraniliprole Nano-SC as well as broadened the high value-added utilization of industrial lignin into pesticide Nano-SC field, which had great economic and environmental benefits.

Preparations of 25 wt% of Pyraclostrobin Nanosuspension Concentrate (SC) Using Lignosulfonate-Based Colloidal Spheres to Improve Its Thermal Storage Stability.

Improving the thermal storage stability of nanosuspension concentrate (SC) prepared from low-melting-point pesticide is a recognized problem. In this work, using pyraclostrobin as the raw material, 25 wt% of pyraclostrobin nano-SC was prepared through a water-based grinding method, and the optimal grinding conditions were obtained as follows: a grinding time of 23 h, D-3911 as dispersant and a dispersant dosage of 12 wt%. The pyraclostrobin nano-SC D90 size prepared based on this best formula was 216 nm. Adding glycerin could improve the stability of nano-SC at room temperature, but its thermal storage stability was still poor. For this problem, sodium lignosulfonate and cetyltrimethylammonium bromide (NaLS/CTAB) colloidal spheres were prepared through electrostatic and hydrophobic self-assembly and characterized. The delamination and precipitation of nano-SC can be significantly improved by adding an appropriate amount of colloidal spheres, and the nano-SC D90 size decreased from 2726 to 1023 nm after 7 days of thermal storage. Farmland experiments indicated the control efficiency of pyraclostrobin nano-SC against flowering cabbage downy mildew disease was about 30% higher than that of SC. Especially after adding the wetting agent, the effect of nano-SC could be comparable to that of commercial Kairun (currently the best pyraclostrobin formulation in the world).

Influence of the Steel Slag Particle Size on the Mechanical Properties and Microstructure of Concrete

The present paper probes into the influence of the steel slag particle size on the mechanical properties and microstructure of concrete, with steel slag serving as the primary raw material. Steel slag with different particle sizes was selected as the partial substitute material for concrete by mechanical grinding. The influence of steel slag on the compressive strength, bending strength, and microstructure of concrete was determined by laser particle size analyzer, specific surface area analyzer, strength experiment, X-ray diffraction (XRD), and scanning electron microscope (SEM). The results show that mechanical grinding has significant effects on the particle size distribution and specific surface area of the steel slag. The optimal grinding time is 20 min and the specific surface area is 0.65 m2/g. D10, D50 and D90 are 0.91 μm, 16.57 μm and 46.40 μm, respectively. The steel slag with a fine particle size can better fill the pores in concrete and improve the compactness, thus enhancing the mechanical properties of concrete. The change in the steel slag particle size does not change the type of hydration products, but the smaller the particle size of steel slag, the better the gelling activity, the larger the hydration products, the denser the structure, and the better the mechanical properties. Therefore, the present study provides an important theoretical basis and practical guidance for the application of steel slag as an additive in the concrete industry.

Magnetic separation for recovering iron resources from acid-leaching tailings of laterite nickel ore through mineral phase transformation

The acid-leaching tailings of laterite nickel ore is a typical hazardous waste in the laterite nickel ore industry. The current treatment involves stacking and landfills, which leads to considerable environmental pollution and resource wastage. The reduction of hazardous waste and the recovery of iron resources have environmental and economic value. In this study, a mineral phase transformation technology was proposed. The suitable transformation conditions were 700 ℃, 30 min, and 30 % CO, and optimal grinding and magnetic conditions were −37 μm content 92.42 % and 143.35 kA·m−1, respectively. Then the iron grade and recovery reached 52.00 % and 80.11 %, respectively. Meanwhile, hematite has converted into strongly magnetic magnetite with saturation magnetization increased from nearly 0 A·m2·kg−1 to 28.49 A·m2·kg−1. And particles transformed from dense to a porous honeycomb structure. Therefore, the mineral phase transformation achieves recovering iron resources during reducing hazardous waste. It proposed a new way of resource utilization of laterite nickel ore acid-leaching tailings which has positive environmental and resource benefits.

The Influence of Excitation Method on the Strength of Glass Powder High-Strength Cementitious Materials

Recycling economy and the re-utilization of solid waste have become important parts of sustainable development strategy. To improve the utilization rate of waste glass, glass powder high-strength cementitious material (GHSC) was prepared by replacing part of the cement in the cementitious material with ground waste glass powder. Firstly, the effect of glass powder particle size on the flexural and compressive strength of GHSC was investigated by the gray correlation method, and the optimal grinding time was obtained. Additionally, the effect of the magnitude of steam curing temperature and the length of steam curing time on the compressive strength and flexural strength of GHSC was investigated, and the mechanism of the effect of the curing regime on the strength was explored by examination of the microstructure. Finally, to simplify the curing process of GHSC, the effects of Ca(OH)2 and Na2SO4 as excitation agents on the compressive strength and flexural strength of GHSC at different dosing levels were compared. The results showed that glass powder with a particle size of less than 20 μm would improve the compressive strength and flexural strength of the specimen. Steam curing can significantly improve the flexural strength and compressive strength of GHSC specimens. At a steam curing temperature of 90 °C for a duration of three days, the compressive strength and flexural strength of GHSC increased by 76.7% and 98.2%, respectively, compared with the standard curing specimens. Ca(OH)2 and Na2SO4 as excitation agents significantly enhanced the compressive and flexural strengths of GHSC under standard curing conditions.

Using modern technologies to improve the vegetable cultivator

This paper explores the selection of high-yielding potato varieties suitable for various soil and climatic conditions, the use of modern scientific technologies in their cultivation, the current state and significance of potato cultivation in the soil and climatic conditions of the Republic of Uzbekistan, and the importance of employing specific techniques such as a motoblock for potato cultivation in homesteads or small farms. The paper also presents the results of theoretical and experimental studies conducted on the study of the grinding angle of the cultivator softener paw. The research findings suggest that the optimal grinding angle for the vegetable cultivator softener claw should be within the range of 25º-30º, ensuring the necessary soil quality and minimal resistance of the working body. This study highlights the importance of selecting appropriate potato varieties and utilizing modern scientific technologies for successful potato cultivation in Uzbekistan.

Preparation and properties of geopolymer containing phosphoric acid-activated fly ash and mechanically-milled kaolinite: Experiments and density function theory

The environmental pollution resulted from the stacking of solid wastes, and the 250 kg CO2 emission caused by calcined a ton of kaolinite have become an urgent problem to be solved. In this study, a novel phosphoric acid-activated geopolymer was developed, which was composed of fly ash (FA), mechanically activated-kaolinite (MAK). The influences of phosphoric acid concentration, mechanical grinding duration, and curing temperature were investigated. Microstructural properties of FAMAK geopolymers were examined through a serious of tests. Furthermore, the Gibbs free energy and nano-scale structure characteristics of acid-activated hydration products were calculated for the first time by using density functional theory. The results show that the optimal mass ratio of FA to MAK is 7:3 with 8 mol/L phosphoric acid, which led to the maximum compressive strength of 36.6 MPa at 56-day. Besides, the optimal grinding time is 3 h and temperature is 40 °C. Moreover, the content of silicon promotes the polymerization reaction. The valence and bonding of aluminum are primarily affected by its coordination number. The key outcomes in this study provides a low-carbon cementitious materials, which can achieve the double benefits of carbon reduction and the utilization of solid wastes.

Comparative analysis of the brazing mechanism and wear characteristics of brazed diamond abrasive with Zr-alloyed Cu-based filler metals

In this work, Zr-alloyed (0 wt%, 0.5 wt%, 1.5 wt%, 2 wt%) Cu-based filler metals were successfully prepared for brazing diamond abrasive tools. The microstructure and brazing mechanism were investigated via scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The effects of brazing temperature and brazing time on the wear properties of diamond abrasive were investigated when the addition amount of Zr is 1 wt%. It found that, adding 1 wt% Zr, the microstructure of the filler metal alloy is uniformly refined and dense. The mechanical properties of the brazed diamond abrasives showed that the brazed Cu-based filler metal with 1 wt% Zr showed the best wear resistance, with the uneven and three-body wear rates reaching 18.8 % and 12.5 %. The findings from the various brazing processes indicated that the optimal grinding performance of the brazed joints was achieved at a brazing temperature of 940 °C and a holding time of 6 min. Under these conditions, the diamond dropout rate was measured at 6.3 %, while the rate of uneven wear reached 18.8 %.

Preparation and strength formation mechanism of alkali-stimulated spontaneous combustion gangue-granulated blast furnace slag backfill.

Spontaneous combustion gangue (SCG) is often used as aggregate in traditional cemented paste backfill (CPB) for mine backfill, but the activation of SCG is insufficient. To stimulate the activity of SCG for the preparation of spontaneous combustion gangue-granulated blast furnace slag backfill (SGB), a new CPB was prepared by activating SCG via a mechanochemical composite activation method and adding ground granulated blast furnace slag (GGBS) to improve its activity. The mixing ratio was optimized by the response surface method and satisfaction function, and the strength formation mechanism was analyzed by scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) and Fourier transform infrared spectroscopy (FTIR). The results showed that SCG had a certain pozzolanic activity, and the optimal grinding time was 30 min. The optimal mix ratio was 82.58% mass concentration, 2.93% alkali content, 30% GGBS content, and 52.92% fine gangue rate. Calcium silicate hydrate (C-S-H) gel and calcium aluminate sulfate hydrate (C-A-S-H) gel were the main reaction products of backfill, and with increasing curing age, C-S-H gel in the reaction system was gradually converted into C-A-S-H gel. FTIR analysis results showed that there were H-O-H, Si-O, and Si-O-T (T was Si or Al) bonds in the product, indicating that C-S-H gel and C-A-S-H gel were formed in the product. A new damage constitutive model was developed. The damage constitutive model could completely describe the backfill stress-strain curve. The study verified the feasibility of preparing cemented paste backfill with SCG and GGBS, which was beneficial to clean coal mine production and environmental protection.