Ultrafine Grinding Research Articles

Optimization design of ultra-fine supplementary cementitious materials ultra-high performance concrete mix proportion based on orthogonal experiment

Traditional ultra-high performance concrete has problems such as high viscosity, high early-age autogenous shrinkage, and high heat release during early hydration. In recent years, with the development of ultra-fine grinding technology, ultra-fine supplementary cementitious materials (USCMs) have received widespread attention, which have higher pozzolanic activity than traditional supplementary cementitious materials. This study investigated the effects of water-binder ratio, silica fume content, and ultra-fine supplementary cementitious materials (USCMs) content on the workability, mechanical properties, and early-age autogenous shrinkage of ultra-high performance concrete (UHPC) based on orthogonal experiments. In orthogonal experiments, multiple factors and levels were introduced, and a combination of range analysis, variance analysis, and multi-factor interaction analysis were combined to determine the optimization level range of each factor. The results showed that the water-binder ratio had the greatest impact on the fluidity, compressive strength, and autogenous shrinkage of UHPC; The content of silica fume had the greatest impact on the flexural strength of UHPC. Compared with the control group, USCMs can significantly improve the workability and rheological properties of UHPC, reduce early hydration heat release, and inhibit the autogenous shrinkage of UHPC.

Stirred media mills of fine and ultrafine grinding for subsequent beneficiation operations

This paper presents a brief review of the designs, characteristics, and operating parameters of Stirred media mills supplied by foreign manufacturers. An analysis of information on Stirred media mills , which are used to improve the efficiency of beneficiation and metallurgical operations, is carried out using available publications. The obtained results indicate the inexpediency of using conventional drum ball mills for flotation separation of ores and concentrates with a fine interpenetration of minerals. The application of conventional mills in extraction of ores and concentrates resistant to cyanidation, where gold is finely disseminated in sulfides, is limited by their high power consumption and the corresponding operating costs. In this work, different types of Stirred media mills are considered, including their vertical and horizontal types. The advantages of Stirred media mills over conventional ball mills, particularly in terms of energy efficiency, are noted. The designs and main characteristics of Stirred media mills , which have received wide application, are presented. According to the data presented in the reviewed publications, the main parameters determining the grinding process in such mills are outlined, including the ratio of bead size to mill feed size, density of grinding medium, density of pulp in the mill, volume loading of beads, stirring speed, etc. The conducted analysis of literature data indicated high efficiency of mills based on agitation of grinding media for fine and ultrafine grinding of ores and concentrates in comparison with conventional ball mills. Given that the volume of ores and concentrates resistant to processing by conventional methods is increasing, the application of Stirred media mills is expected become more widespread, thereby increasing the efficiency of subsequent beneficiation and metallurgical operations.

Effects of ultrafine grinding on nutritional, physicochemical and protein composition of Acheta domesticus powder

Acheta domesticus is a new source of high-quality protein, but the accessibility and acceptability of protein is notably limited by the particle size of the house cricket powder, and little information about the effect of particle size on the house cricket powder had been reported. In this study, four kinds of ultrafine cricket powder were obtained by two industrial methods, and compared with the traditional grinding powder. The results illustrated that ultrafine grinding technology could increase the powder properties, such as the thermal stability, crystallinity, color brightness, protein extraction rate and amino acid content, especially the essential amino acid (EAA) content were significantly improved. And the properties and nutrient release of the powder are mainly related to the particle size rather than the method. The results have a certain guiding effect on the development and application of ultrafine house cricket powder as a multifunctional nutrient.

Impact of cocoa variety on physical and chemical properties, reconstitutability, and flowability of cocoa powders

Cocoa of the Criollo, Forastero, and Trinitario varieties grown in the same production area of the Republic of the Congo were simultaneously harvested and similar post-harvesting operations (fermentation in crates followed by sun-drying) were performed. Cocoa powders were then produced according the same process consisting in successive roasting, grinding, fat extraction by pressing, and ultrafine grinding of the defatted mass. In order to investigate the influence of cocoa variety, the main physical and chemical properties (proximate composition, pH, particle size and shape distributions) of powders were characterized and related to cocoa powders abilities to reconstitute and flow. The three varieties showed very close proximal compositions, with lipid contents varying between 21 and 23 % (w/w), which classifies them as defatted cocoa powders. Cocoa powders of all varieties were non-wettable, and not soluble (solubility index around 0.15 g/g), consistently with their high lipid content. The fatty, fibrous, and proteic nature of the product has an impact on the grinding process, resulting in non-wettable powders and particles of varying sizes and shapes. All powders had bimodal particle size distributions, with large particles around 500 μm and small ones around 25 μm. However, slight differences between varieties were observed for some shape and functional properties. Trinitario and Forastero cocoa particles were slightly less spherical. The Criollo cocoa powder was relatively more compressible than the Trinitario variety. No significant difference of flow properties was attributable to cocoa variety. Basic flowability energy of all cocoa powders were relatively high, ranging from 908 to 973 mJ, which could denote a low aptitude to flow that may be related to the probable softness and stickiness of particle surface due to the high lipid content of cocoa powders. Specific energy values required to make studied cocoa powders flow were in the range between 6.61 and 6.99 mJ/g, which corresponds to intermediate values indicating a moderate level of cohesion and thus a fair flowability. The flow parameters obtained from the shear cell test showed no significant difference of cohesion (comprised between 1.54 and 1.70 kPa), flow factor (ranging from 2.53 to 2.76), and internal angle of friction (between 33.4 and 33.9°) linked to cocoa variety. This may be explained by the impact of particle size, as higher particles are generally less cohesive due to their lower surface specific area implying less interparticular contact points. Apart from these slight differences, all varieties showed similar properties and thus could be blended instead of being sorted in the cocoa manufacturing process. This study permitted to highlight that the terroir, the method of harvesting and preparing the beans, and then producing the powder have probably more impact on the physical and chemical and functional properties of cocoa powders than their variety.

Study on the effect and mechanism of polyethylene oxide and alum in flotation separation of fine smithsonite/calcite

The flotation separation of fine smithsonite and calcite has always been a challenging issue in the mineral processing industry. Both minerals are microfine particle distribution in nature, requiring ultra-fine grinding to maximize their liberation, which makes their flotation separation difficult. This study investigated the effects of PEO (Polyethylene oxide) and alum as combination agent on the flotation separation of fine smithsonite and calcite. The research results showed that using PEO and alum as combination agent can effectively separate fine smithsonite and calcite. PEO has a flocculation effects on both minerals, and Alum has better selective adsorption and flocculation effects on calcite, thereby effectively reducing the recovery of calcite. After treatment with PEO and alum, soluble starch tends to adsorb on the surface of calcite more than smithsonite, selectively depressing calcite in flotation separation, thus allowing for the effective flotation separation of fine smithsonite and calcite.

Development of a novel functional food based on ultrafine grinding and medicinal food raw materials formula

AbstractMedicinal food raw materials refer to those raw materials with food and possess medicinal value. They were particularly suitable for developing novel functional food. In this study, a novel functional food based on ultrafine grinding treatment of Ganoderma, yam, wolfberry, Rhizoma polygonati, raspberry, and euryale ferox (GYWRRE) with a specifically designed formula was developed and characterized. The results were shown that the ultrafine GYWRRE powder presented a relatively regular structure and smooth surface. It had notable decreases in fluidity and oil‐holding capacity but increases in characteristic nutrient content and antioxidant capacity. The ultrafine GYWRRE powder also could prevent oxidative stress in C2C12 cells by reducing the contents of reactive oxygen species and methylene diphenyl diisocyanate, inhibiting cell apoptosis, and increasing expressions of heme oxygenase‐1 and NQO1. The results of this study were demonstrated that medicinal food raw materials and ultrafine grinding had great applications potentials in developing functional food.Practical applicationsMedicinal food refers to those natural ingredients that serve both as food and possess medicinal value. Ultrafine grinding technology is a meticulously engineered method capable of grinding raw materials to the micron level, thereby increasing their surface area, improving their bioavailability, and potentially enhancing their medicinal properties and bioavailability. This study developed an ultrafine grinding treatment of Ganoderma, yam, wolfberry, Rhizoma polygonati, raspberry and euryale ferox (GYWRRE) with a specifically designed formula. The characteristics of the ultrafine GYWRRE powder contained particle size, morphology, colorimetry, liquidity, hydration, adsorption, and characteristic nutrients were characterized. The antioxidant capacity in vitro and in cells as well as the possible mechanism were also explored. The results of this study will be helpful for development of novel functional foods.

Effect of ultrafine grinding on the structure and physical properties of pregelatinized rice starch.

This study used a combination method of ultrafine grinding and pregelatinization to modify rice starch (RS) to delay its retrogradation and provide a rationale for prolonging rice product shelf life. The structure and physicochemical properties of the pregelatinized ultrafine grinding rice starch (PURS) were compared with those of RS, ultrafine grinding rice starch (URS), and pregelatinized rice starch (PRS). The microstructure, molecular weight, branched starch length distribution, short-range order, crystal structure, and physical properties of RS, URS, PRS, and PURS were analyzed, respectively. Results showed that RS, URS, PRS, and PURS granules exhibited similar spherical or polygonal shapes, and the content of amylose and short-branched starch in PURS increased compared with RS, URS, and PRS. Furthermore, the cross-polarization of PRS and PURS disappeared. Long-chain amylopectin and average molecular weight of PURS decreased significantly after ultrafine grinding. Our study suggested reduced breakdown value and setback value and improved gel stability, and PURS was beneficial for delaying retrogradation compared to RS, URS, and PRS. The ultrafine grinding method improved the water swelling capacity (WSC), solubility, pasting properties, and gelation properties of PRS. The hardness of PURS was reduced by ultrafine grinding. These suggest that the combination of ultrafine grinding and pregelatinization could improve the properties of RS. Pearson's correlation analysis showed that the structure of PURS significantly influenced the physicochemical properties. The present study was helpful in better understanding the importance of ultrafine grinding in improving the anti-retrogradation of PURS and provided new insights into extending the shelf life of rice products by ultrafine grinding and pregelatinization.

Study on electrostatic separation technology and characterization of shrimp shell protein

Shrimp shell protein is a high-quality protein with wide-ranging applications in feed, pharmaceuticals, and food industries. However, current methods for its production often involve the use of harsh chemicals, resulting in the generation of polluting effluents, making green alternatives highly desirable. This study combined demineralization of shrimp shell (Fenneropenaeus chinensis, Osbeck, 1765) with ultrafine grinding and electrostatic separation techniques to extract and separate the protein. The research findings revealed that shrimp shell contain 40.64 ± 0.52 % protein, which increased to 52.61 ± 1.12 % after demineralization treatment. Impact grinding, compared with cutting grinding, facilitated the production of demineralized shrimp shell ultrafine powder with more uniform distribution and smaller particle size. However, only demineralized shrimp shell powder obtained through cutting grinding achieved an increase in protein purity from 61.82 ± 0.75 % to 72.72 ± 0.83 % after electrostatic separation. The electrical properties of shrimp shell protein and chitin suggest that shrimp shell protein is more conductive than chitin, while shrimp shell chitin is more insulating and less prone to charge exchange with the counter material in a direct current electric field. The total amino acid content of shrimp shell protein obtained through electrostatic separation (715.831 mg/g protein) was higher than that obtained through traditional wet extraction (533.455 mg/g protein). Additionally, the amino acid score (AAS) of shrimp shell protein obtained via electrostatic separation was higher compared to that obtained via wet extraction. The wet extraction process significantly influenced the nutritional and structural properties of shrimp shell protein. This study confirms the potential application of electrostatic separation technology in the extraction of animal-derived shrimp shell protein.

Preparation of potato granules powder by low temperature ultrafine grinding and its effect on the texture of bread

AbstractIn this article, low temperature ultrafine grinding and other three kind of crushing methods were used to prepare potato granules powder. And the swelling power and solubility, water‐holding capacity, gelatinization characteristics, particle size, and chromaticity of different particle size levels of potato granules powder were determined. The experimental results showed that the potato granules powder prepared by low temperature ultrafine grinding had the highest solubility and swelling power, and the highest degree of pre‐gelatinization; With the increase in the addition of potato powder, the water absorption of the dough increased, and been more rheological. The volume of bread gradually decreases and the firmness increases. With the decrease of potato granules powder size, the water absorption of dough decreases and the bread hardness increases. In this experiment, when the grain size of potato powder was 200 mesh and the addition amount was 2%, the sensory score was the highest and the taste was the best. The result provides theoretical and practical basis for the production of potato bread and the comprehensive utilization of potato resources.Practical applicationsThe present study demonstrates the effective preparation of potato whole powder particles through low temperature ultrafine grinding. Comparative analysis with shear grinding, ball grinding, and room temperature grinding reveals that low temperature ultrafine grinding yields superior solubility, swelling, and gelatinization characteristics. Furthermore, incorporating 200 mesh fine potato powder in bread formulation significantly enhances dough rheological properties and water absorption while improving bread hardness and flavor. The findings offer a solid theoretical and practical foundation for the production of potato bread and the comprehensive utilization of potato resources.

Supergene Oxidized Gold-Silver Deposits in the Americas: Guides for Geologists

Editor’s note: The aim of the Geology and Mining series is to introduce early career professionals and students to various aspects of mineral exploration, development, and mining in order to share the experiences and insight of each author on the myriad of topics involved with the mineral industry and the ways in which geoscientists contribute to each. Abstract Supergene oxidation is a process that has created some of the largest gold and silver orebodies in the Americas, including the Carlin-type (sediment-hosted) gold deposits and Round Mountain in Nevada; Yanacocha and many similar deposits in Peru; Cerro Rico, Bolivia; and Pueblo Viejo, Dominican Republic. Oxidation can make sulfide-bearing gold-silver deposits economic by converting refractory gold-silver–bearing sulfide minerals to minerals that can be leached by dilute cyanide solutions. The use of cyanide heap leaching or tank leaching enabled open-pit mining of low-grade oxidized gold deposits starting in the 1960s. This revolutionized gold mining which, combined with the end of the dollar gold standard in 1971, led to a huge increase in gold production, particularly in the Americas where the technology has been widely applied. During weathering and oxidation of sulfide minerals, particularly pyrite, associated gold and silver form supergene minerals in the oxidation zone but are only transported over short distances (centimeters to meters) due to low solubility of the metals, so they do not form enrichment zones. Gold forms Au0 grains of 1 to 25 µm size and high fineness, as well as invisible gold associated with jarosite and iron oxyhydroxides by sorption or substitution. Silver forms halides and native silver, which may be accompanied by metastable hypogene acanthite. Silver in jarosite, alunite, and Mn oxides is refractory. The economic advantages of near-surface oxidized deposits are that they can be mined by open pit with low costs, commonly not requiring stripping or blasting. Run-of-mine ore is sent directly to leach pads, although some ores may require prior crushing and grinding with agglomeration of fine material such as clays. Oxidized ore is processed by heap leaching using dilute sodium cyanide solution and gold and silver recovered by zinc cementation or on activated carbon. Some ores require grinding and are processed by tank leaching. The hypogene sulfide minerals below the oxidized zone are typically refractory and require at least ultrafine grinding for leaching to be effective, or high-cost oxidation technology for roasting, autoclaving, or bio-oxidation. The sulfide-rich portions of deposits are often not exploited for many decades after discovery, if at all. To explore for supergene oxidized deposits, the exploration geologist requires knowledge of geology, oxide mineralogy, geomorphology, hydrogeology, and the (paleo)-climate, as well as open-pit mining, hydrometallurgy, cyanide leaching, and carbon technology, topics that are introduced here with case studies.

Improved energy transfer model for mechanistic scale-up of stirred media mills

Wet-operated stirred media mills are commonly used in the field of fine and ultra-fine grinding. Depending on the application, there are different mill geometries, sizes and mill equipment materials of which the grinding chamber lining and the stirrer are made. Increasing energy prices demand an energy-efficient mill operation for a desired product, which can be achieved with mechanistic stress models. Here, besides the mill geometry and volume, the process parameters and various energy-transfer-coefficients are of importance. In this work, the impact of different mill equipment materials affecting the mill-related-energy-transfer-coefficients on performance prediction and scale-up using the advanced stress model are investigated. It was found that the mill-related-energy-transfer-coefficients as well as the improved grinding-media-energy-transfer-coefficients have a significant effect on the prediction precision of the comminution times and specific energies for chosen target particle sizes.

Reducing Dark-State Current for GaAs Photoconductive Semiconductor Switch by Ultrafine Grinding Process

Reducing Dark-State Current for GaAs Photoconductive Semiconductor Switch by Ultrafine Grinding Process

Mechanistic study of the effects of ultrafine grinding on the surface properties of anthracite coal particles and interface regulation on froth flotation under multifactorial influences

Anthracite, a valuable and scarce coal, typically requires systematic liberation for deep deashing, wherein the particle size reduces to the micron level upon ultrafine grinding. Changes in the physicochemical properties of anthracite particles induced by ultrafine grinding significantly impact subsequent flotation. Accordingly, in this study, a scanning electron microscopy (SEM)-energy-dispersive X-ray spectroscopy (EDS) system, an Opton IPCAS maceral analyzer, a high-sensitivity microelectromechanical balancer, and an X-ray photoelectron spectrometer (XPS) were employed to investigate the changes in the physicochemical properties of the anthracite particle surface during ultrafine grinding. The flotation efficiency of ultrafine anthracite coal is determined by various factors such as the extent of sample liberation, surface wettability, and the state of inorganic mineral coatings. During the initial phase of ultrafine grinding, the comminution efficiency of the sample is high, leading to a progressive increase in the hydrophobicity. However, suboptimal flotation performance results from inadequate liberation. When the sample is liberated to an ultrafine scale, a higher degree of liberation is achieved. The particle surfaces become increasingly covered with inorganic minerals, accompanied by intensified oxidation, leading to a gradually reduced particle hydrophobicity that impaired the flotation performance. This study advances our knowledge on the mechanism by which ultrafine grinding alters the physicochemical properties of anthracite coal particles and affects the flotation processes. The theoretical framework of this study provides crucial insights for interface regulation in the preparation of ultra-low ash anthracite coal and ultrafine coal flotation.

Ultrafine grinding of mica in organic medium for ink-jet printing process

This work investigates the grinding of a mica powder in an organic medium in order to make the particle size compatible with the inkjet process using a high-energy ball mill. A detailed protocol leading to size reduction without altering structural properties of interest of this material has been successfully developed. Two steps are necessary, namely dry grinding and wet grinding in ethanol. The final particle size obtained was D90 = 1.9μm which is very close to the size requirement of the inkjet process related to the printing nozzle diameter (52μm). The mica morphology in the form of platelets was shown to be conserved by means of scanning electron microscope observations. X-ray diffraction confirmed that the mica did not undergo any change in its crystallographic structure. The decrease in particle size was revealed by the broadening and intensity drop of the diffraction peaks. Thermogravimetric analyses highlighted a shift of dehydroxylation reactions towards lower temperatures, which is also coherent with platelet size reduction.

Effects of different wall-breaking methods on the nutrient release of Ganoderma lucidum spore powder during in vitro digestion.

The hard double-walled structure of Ganoderma lucidum spore powder (GLSP) is difficult for the human body to digest, so it is very important to break the wall of GLSP. In this study, the wall of GLSP was broken by mechanical milling at room temperature (MM-R) and ultra-fine grinding at low temperature (UFG-L), respectively. Compared with MM-R, UFG-L could better retain the sporangium powder's morphological and structural integrity. During in vitro digestion, compared with unbroken GLSP, the released amounts of polysaccharides and triterpenes from broken GLSP were significantly increased, and they increased with the increase of specific surface area. The bioaccessibility of polysaccharide and triterpene from unbroken GLSP after the intestinal stage were 29.52% and 5.37%, respectively. The bioaccessibility of polysaccharides and triterpene from broken GLSP by MM-R after the intestinal phase were 39.73-72.45% and 16.44-24.97%, while those by UFG-L were 44.53-104.18% and 12.96-32.90%, respectively. The active ingredients of broken GLSP showed better digestion and absorption abilities than unbroken GLSP. Moreover, the specific surface area of GLSP by UFG-L was lower than that by MM-R, and the bioaccessibility of GLSP by UFG-L was higher than that by MM-R. © 2024 Society of Chemical Industry.

Influences of superfine-grinding and enzymolysis separately assisted with carboxymethylation and acetylation on the in vitro hypoglycemic and antioxidant activities of oil palm kernel expeller fibre

The synergistic effects of ultrafine grinding and enzymolysis (cellulase and Laccase hydrolysis) alone or combined with carboxymethylation or acetylation on the hypoglycemic and antioxidant activities of oil palm kernel fibre (OPKEF) were studied for the first time. After these synergistic modifications, the microstructure of OPKEF became more porous, and its soluble fibre and total polyphenols contents, and surface area were all improved (P < 0.05). Superfine-grinding and enzymolysis combined with carboxymethylation treated OPKEF exhibited the highest viscosity (13.9 mPa∙s), inhibition ability to glucose diffusion (38.18%), and water-expansion volume (3.58 mL∙g−1). OPKEF treated with superfine-grinding and enzymolysis combined with acetylation showed the highest surface hydrophobicity (50.93) and glucose adsorption capacity (4.53 μmol∙g−1), but a lower α-amylase-inhibition ability. Moreover, OPKEF modified by superfine-grinding and enzymolysis had the highest inhibiting activity against α-amylase (25.78%). Additionally, superfine-grinding and enzymolysis combined with carboxymethylation or acetylation both improved the content and antioxidant activity of OPEKF's bounding polyphenols (P < 0.05).

Methods for obtaining humate-containing fertilizers from brown coal

ABSTRACT The purpose of the study is to examine the main methods of obtaining fertilizers and optimizing processes. Using methods of analysis, comparison, and experimentation, three main approaches to obtaining fertilizers were identified: grinding and mixing with potassium hydroxide (KOH), ultrafine grinding with chemical additives, and a complex method for processing caustobioliths. Comparative analysis of the investigated methods allowed for identifying their advantages, disadvantages, and effectiveness. The key result was the ability to determine the most effective method for producing humate-containing fertilizers from brown coal, depending on specific production conditions and requirements. The results of the study showed that the ultrafine grinding process with chemical additions, such as urea and alkali metal hydroxides, showed promising potential for creating highly effective humate-containing fertilizers from brown coal, in addition to the comparative analysis. After thorough optimization, this technique showed improved fertilizer utilization and superior plant uptake, making it a strong contender for sustainable farming methods. Nevertheless, achieving optimal results requires detailed process parameter optimization. The study underscores the importance of using brown coal in humate-containing fertilizer production as an environmentally safe and sustainable approach. The results can contribute to further development and improvement of humate-containing fertilizer production methods, promoting sustainable agriculture and increased crop productivity.

Ultrafine grinding improves the nutritional, physicochemical, and antioxidant activities of two varieties of whole-grain highland barley.

Effects of ultrafine grinding on the nutritional profile, physicochemical properties, and antioxidant activities of whole-grain highland barley (HB) including white highland barley (WHB) and black highland barley (BHB) were studied. Whole-grain HB was regularly ground and sieved through 80 mesh get 80 M powder, and HB was ultrafine grounded and sieved through 80 mesh, 150 mesh, and 200 mesh get 80UMM, 150UMM, and 200UMM samples. Particle size of WHB and BHB reduced significantly after ultrafine grinding. As the particle size decreased, moisture content of WHB and BHB decreased significantly, whereas fat content increased significantly. Redistribution of fiber components in WHB and BHB from insoluble to soluble fractions was also observed. Wherein, content of soluble pentosan of WHB and BHB increased significantly from 0.56% and 0.78% (80M) to 0.91% and 1.14% (200UMM), respectively. Damaged starch of WHB and BHB increased significantly from 8.16% and 8.21% (80M) to 10.29% and 10.07% (200UMM), respectively. Content of phenolic acid and flavonoid of WHB and BHB and associated antioxidant capacity were increased after ultrafine grinding. Color of L* value increased significantly, a* and b* values decreased significantly, indicating the whiteness of WHB and BHB was increased after ultrafine grinding. Pasting temperature of WHB and BHB decreased, whereas peak viscosity increased. X-ray diffraction patterns of HB showed typical A- and V-style polymorphs and the relative crystallinity of HB decreased as the particle size decreased. Taken together, ultrafine grinding has shown great potential in improving the nutritional, physiochemical, and antioxidant properties of whole-grain HB. Our research findings could help better understand the ultrafine grinded whole grain HB in food industry.

ИССЛЕДОВАНИЕ ВЛИЯНИЯ МНОГОЗАХОДНЫХ ВИНТОВЫХ ЛОПАСТЕЙ НА ЭНЕРГЕТИЧЕСКОЕ СОСТОЯНИЕ МЕЛЮЩИХ ТЕЛ В БИСЕРНОЙ МЕЛЬНИЦЕ

The distribution of bead mills in industrial enterprises of the processing industry for fine and ultra-fine grinding of various materials, the need for their improvement is demonstrated. A new design of a horizontal bead mill with multi-start screw blades is considered. This allows increasing productivity and reducing specific power consumption. The purpose of the studies was to assess the possibility of increasing the efficiency of the bead mill when screw blades are installed on the paddle shaft and their influence on the energy state of grinding bodies. Using the EDEM software product, the mathematical planning method of the experiment, a simulation of the process of movement of grinding bodies in the model of the body part of the bead mill was carried out when it was equipped with a pair of two-way screw blades. The obtained regression equation was studied. It describes the dependence of the averaged value of the total kinetic energy of the grinding body on varying factors: the angle of rotation of the beginning of the blade screw starts, the distance between the screw blades, the pitch of the screw blade, and the angular speed of the blade shaft. The possibilities of increasing the average value of the total kinetic energy of the grinding body and regulating the energy state of the grinding bodies have been established. The feasibility of conducting further theoretical and experimental studies aimed at studying the process of grinding material in a bead mill with multi-start screw blades and establishing rational design and technological parameters that ensure increased efficiency of this process has been determined.

UPGRADING AND SURFACE COATING OF EGYPTIAN WHITE SAND WITH POLYMERS AND SILANES

Egypt is endowed with huge reserves of filler minerals, such as silica sand which form approximately 95% of the Earth's crust. The silica sand industry is used in many fields, such as pharmaceutical practices, chemicals, glass, ceramics, electronics, and photovoltaic industries. The aim of this study is to remove impurities from silica sand and apply surface modification processes to enhance its value for various industrial manufacturing applications. Various processing techniques, including classification, attrition scrubbing, magnetic separation, ultra-fine grinding and surface modification, were conducted throughout the study. The results indicated that attrition scrubbing to the classified size fraction of -0.6 + 0.1 mm was capable of reducing the iron concentration from 0.068% to 0.045%. Utilizing the Box-Behnken design, the optimal conditions for magnetic separation were identified, resulting in a decrease in iron content down to 0.012%. Simultaneously, the silica content increased from 99.05% to 99.76%. The results of ultrafine grinding using an attritor mill revealed that a grinding time of 2 hours is sufficient to reach a size suitable for the coating process. Surface modification of the produced ultrafine sand was conducted using polymers and silanes. The treated sand was characterized using SEM, zeta potential, adsorption density, and FTIR measurements. Notably, hydrophobicity increased, accompanied by an increase in particle size. Simultaneously, the surface becomes flatter, indicating the formation of a thin layer. Consequently, the coated sand proved to be a satisfactory material that met the criteria to be used as a filler in coating and paints.