Grinding Plant Research Articles

Effects of Heat Treatment and Erosion Particle Size on Erosion Resistance of a Hypereutectic High-Chromium Cast Iron

This research addresses the erosive resistance of a hypereutectic high-chromium cast iron subjected to solid particle erosion. The study stems from a specific application of high-chromium cast iron, i.e., the critical surfaces of large industrial fans operating in a cement clinker grinding plant where such damage is a limiting factor for the components’ lifespan. A dedicated experimental investigation on the impact of substrate microstructure and erodent particle size on erosion resistance was set. The experimental campaign, conducted on a dedicated test bench per the ASTM G76 standard, comprised the analysis of the as-received, tempered, and destabilized conditions for the cast iron. From a preliminary image analysis of the microstructural features, two diameters of the erodent powder for the erosion tests were defined. The observed erosion rate decreased with the increase in the mean particle diameter of the erodent, indicating more severe erosive conditions for smaller particles. From the analysis of the worn surfaces, it was possible to highlight the involved mechanisms concerning the considered test combinations. For the as-received condition, the erosion rate with the larger mean particle diameter of the erodent decreased three times compared to the smaller one. For the heat-treated conditions, the erosion rate was halved with the larger mean particle diameter of the erodent. The proposed analysis, intended to acquire more insight into the limiting factor for the components’ lifespan for erosive wear damage, proved that erosion resistance is not dependent on the material’s hardness. The contribution of the mean particle diameter of the erodent is predominant compared to the substrate conditions.

INNOVATIVE PROCESS LINE FOR MATERIAL SAMPLE PREPARATION

ABSTRACT. The successful establishment and sustainable development of mining enterprises depends on a number of factors, including geological research, management of mineral extraction and processing processes, and sample preparation technology. The sample preparation plants that are currently used have a multi-stage technological process, often with manual transfer of material between technological operations. Standard crushing and grinding equipment with a low degree of grinding, high metal consumption and overall dimensions is used. Separation of material by size also occurs on standard screens, which are poorly suited for sample preparation. The purpose of the work is to substantiate an innovative technological scheme for preparing mineral samples for laboratory analysis. The determining unit of the production line is a vibrating jaw crusher with an inclined crushing chamber, which has a degree of material grinding of more than 100 and allows one to obtain a final product with a particle size of -1 mm in one pass in an open crushing cycle, which reduces the number of overload devices that significantly affect sample clogging with material. Horizontal loading of the source material and unloading of the crushed material makes it possible to arrange all equipment in a horizontal plane, eliminate large-sized metal structures and ensure ease of maintenance. The vibrating screen of the improved design has a complex working profile, which provides a significant increase in the path of transportation of material particles along the sieving surface compared to its length, effective cleaning of the mesh and its visual inspection through the transparent lid, which eliminates clogging of the material of the previous sample. The working surface is a set of sieve cards that allow quick replacement of the worn part of the screening surface. The technical characteristics of the equipment and the general view of a small-sized modular crushing and grinding plant are presented.

Development of a drying and grinding plant for a mixture of milling peat with water treatment sediments for the production of construction and ceramic materials

The strategy of sustainable development assumes proper management of man-made waste, capable of ensuring their reuse and reducing the associated environmental burden on the environment. A promising direction for the utilization of water treatment sediments is the possibility of their use in a mixture with peat as a potential raw material for the production of construction and ceramic materials. An installation has been developed for the selection of milling peat, its mixing with water treatment sediments, drying of the resulting mixture and grinding for subsequent use in the production of construction and ceramic materials.

Development of a Drying and Grinding Plant for a Mixture of Milled Peat and Water Treatment Sediments for the Production of Construction and Ceramic Materials

Development of a Drying and Grinding Plant for a Mixture of Milled Peat and Water Treatment Sediments for the Production of Construction and Ceramic Materials

ANALYSIS OF THE FLOW OF A FIBROUS SUSPENSION IN A GRINDING PLANT IN THE PRODUCTION OF FINE CELLULOSE

Of the various methods for obtaining microcrystalline cellulose (mechanical, chemical, thermomechanical, planting cellulose in powder form from its solutions), the most common is acid hydrolysis of cellulose. The difficulty of obtaining MCC from vegetable raw materials is that, in addition to cellulose, it contains in its composition such compounds as lignin, hemicelluloses, various extractive substances and an insignificant percentage of minerals. When grinding plant fibers in an aqueous medium, both a purely mechanical process of changing the size and shape of fibers and a colloidal chemical process called fiber hydration occurs. Mechanical phenomena are expressed in the shortening of fibers, their longitudinal splitting into fibrils, an increase in the outer surface and the number of free hydroxyl groups on their surface. The term hydration refers to colloidal chemical phenomena that begin with the swelling of hydrophilic plant fibers.
 The paper considers methods for obtaining microcrystalline cellulose and factors influencing the development of a fibrous suspension isolated from coniferous wood species in a grinding plant with inertial bodies. Multiphysical models of the flow of fibrous suspension in the installation are constructed. A study of the effect of grinding a fibrous suspension on the process of obtaining fine cellulose was carried out. The indicators of the finished product are given. The change in the degree of polymerization of cellulose that has previously passed the grinding stage, with different degrees of grinding according to the Shopper-Rigler, is analyzed. Data on cost reduction and resource savings (acid concentration, temperature and processing time) in the process of obtaining fine cellulose are presented.

Obtaining microcrystalline cellulose based on biodamaged wood as a way to improve the sanitary and forest pathological state of forests

The paper-forming properties of the fibrous suspension and the physical and mechanical characteristics of the finished types of paper largely depend on the type of initial plant material. Depending on what purpose it is necessary to obtain paper, a composition is made from fibrous semi-finished products of plant origin in various proportions. Basically, paper is produced from two, three, or more fibrous semi-finished products, forming a paper composition according to the type of fibers, and sometimes from one fibrous semi-finished product, suitably prepared for this. The properties of the original fibrous semi-finished products to a large extent affect not only the properties of the finished paper, but also determine the technological mode of their processing. This paper shows the possibility of obtaining cellulose from biodamaged wood. The mechanical strength characteristics of the finished castings are analyzed after grinding the fibrous mass on a knifeless grinding plant of the “jet-barrier” type. The conditions for obtaining microcrystalline cellulose from biodamaged wood are determined.

Technological and economical investigation of glaze preparation using dry stirred media mill

Ceramic tiles are the most common building material for floor and wall coverings in many countries. Glazed tiles are produced from mixture of frits and some additional raw materials applied on the surface of green tiles and subjected to a firing process. A new method of processing of glaze that is dry stirred media mill was investigated in a pilot grinding plant. The produced glaze particle size, shape and surface area are measured. The comparison was made with the product of conventional wet discontinue ball mills using the same wall tile glaze recipes. The results indicated that dry stirred media mill can provide product that have finer particle size distribution, more stable product compared to the conventional wet ball milling. The glaze thermal expansion and optical properties such as colour (L, a and b parameters) of the produced glazes were measured and comparison was also made in details. Finally, the microstructural characteristics of the produced glazes were determined using scanning electron microscopy (SEM). The results have shown that dry stirred media mill enhances glaze properties and process economy considerably.

SAFETY INSPECTION OF PRESSURE VESSELS AT AN ENGINE GRINDER IN AGRESTINA-PE

Pressure vessels are critical components in internal combustion engines as they withstand high pressures of oil, air, steam or other fluids. Failure of a pressure vessel can result in loss of containment, personal injury, equipment damage and, in severe cases, even explosions. Therefore, it is crucial to carry out periodic and rigorous inspections of these vessels in an engine overhaul to ensure their integrity and safety. This article discusses the steps of inspection in pressure vessels in an engine grinding plant, including inspection of pressure vessels containing argon gas stored to perform aluminum welding, as well as verification of design specifications, external visual evaluation, dimensional verification, ray inspection, visual inspection on compressors, which is important to extend its useful life and prevent accidents, inspection is performed according to specific standards and codes, such as ASME and API, and can be performed by internal or external inspectors, depending on the complexity of the equipment

An experimental and numerical study of the solid particle erosion damage in an industrial cement large-sized fan

The present paper addresses the wear failure analysis of a large-sized centrifugal fan operating in a cement clinker grinding plant. Within cement production, the calcination at middle and high-temperature values (from 120 °C to 400 °C depending on the process parameters) of the raw material requires such a process fan, which also ensures the draft and feed of the flue gases and combustion air needed for the operation of the main equipment of the cement factory. To detect and analyze the impact conditions within the heavy-duty fan, Computational Fluid Dynamics (CFD) analyses were performed. The analysis of the numerical results shows that the relevant fan surfaces are affected by different impact velocities and angles, generating non-uniform erosion patterns similar to the on-field detections. Besides, the obtained comprehensive description of the flow and contaminants behaviors through the entire flow path enables setting up the subsequent experimental investigation. The erosive wear behavior of a Fe-Cr-C hardfacing cast iron and wear-resistant steel was tested through a test rig constructed for the purpose of being in accordance with the ASTM G76 standard. The test bench was adapted to manage the raw meal powder used in the cement factory to reproduce the actual operating conditions. The results show a greater capability of Fe-Cr-C hardfacing cast iron to face the erosion phenomenon in terms of lower values of material loss over the exposure time. These findings, coupled with the metallographic analysis to detect the erosion mechanisms (ductile and/or brittle), help a better prediction of the fan operating life. The investigation showed the reliability of the numerical/experimental coupled approach in assessing the actual erosion magnitude and the influence of the impact angle on the erosion phenomena. This coupled approach gains a further understanding of the proper design of manufacturing and maintenance activities, covering several project steps from material selections to the scheduled and overhaul operations. A reliable operating-life prediction allows manufacturers and operators to obtain production and economic goals.

Use of a knifeless grinding plant for waste paper recycling

The article considers the problem of recycling waste paper and the main reasons for the deterioration of paper-forming and physical and mechanical indicators of finished products during recycling of recycled fiber. A study was carried out on the effect of increasing the number of recycling cycles of waste paper of the MS-8V brand on such indicators as fractional composition, breaking length and resistance of paper to punching when using a jet-barrier type knifeless grinding unit.

65,000-years of continuous grinding stone use at Madjedbebe, Northern Australia

Grinding stones and ground stone implements are important technological innovations in later human evolution, allowing the exploitation and use of new plant foods, novel tools (e.g., bone points and edge ground axes) and ground pigments. Excavations at the site of Madjedbebe recovered Australia’s (if not one of the world’s) largest and longest records of Pleistocene grinding stones, which span the past 65 thousand years (ka). Microscopic and chemical analyses show that the Madjedbebe grinding stone assemblage displays the earliest known evidence for seed grinding and intensive plant use, the earliest known production and use of edge-ground stone hatchets (aka axes), and the earliest intensive use of ground ochre pigments in Sahul (the Pleistocene landmass of Australia and New Guinea). The Madjedbebe grinding stone assemblage reveals economic, technological and symbolic innovations exemplary of the phenotypic plasticity of Homo sapiens dispersing out of Africa and into Sahul.

Preparation of stem vegetable raw materials in the production of briquetted feed mixtures

To maintain the stable competitiveness of Russian agricultural products in the domestic and foreign markets, it is necessary to find reserves for the use of non-waste technologies using domestic raw materials in full. In the conditions of growing feed production, providing the feed industry with components of plant origin, an important role belongs to the use of inexpensive rough grass feed. Their use allows more rational use of plant stem forage, completely balances the diet of animals, mechanizes the distribution of feed, reduces its losses during transportation, distribution and eating, and thus significantly reduces the cost of livestock products. In connection with the production of new types of products in the form of briquettes, the production technology of which involves the introduction of stem plant materials, the process of their preparation is of great importance. Studies of the process of grinding stem plant raw materials with different moisture content on a hammer crusher were carried out, during which the optimal parameters of its operation were determined, which make it possible to reduce the energy intensity of the grinding process by 8.5-10.5% and improve the quality of the produced briquettes

THE USE OF COAL AS FUEL FOR CEMENT MANUFACTURING AT PT. SEMEN GRESIK

The conversion of fuel type, from oil to coal has considerable consequence as coal has very different combustion characteristics from oil. As the price of coalnis much lower, the process is viable.The use of coal as fuel in the cement industry requires more effort in technological treatment, such as: installationof the grinding plant, modification of the existing equipment, and the monitoring and continuous adjusting the blend. As the “ash” in the coal used for firing will combine with the raw mix during burning and thus causes a quite considerable change in the composition of the clinker. The combination of different blends of coal with different ash contents has to be carefully monitored to ensure clinker quality.

Keys to best practice comminution

Comminution circuits are composed of multiple unit operation, with the objective of reducing mined rock to a size where valuable minerals grains are liberated from gangue. Optimal comminution is critical to achieve efficient mineral separation. There are three reasons for writing this paper. For operators to manage good operations; for designers to produce workable designs; and for educators to provide useful education for mineral process engineers. In all cases, understanding of the transfer size (T80) between the SAG mill and the ball mill is critical to achieve best economics in a semi-autogenous mill (SAG) grinding plant. T80 is important to operators because when the SAG energy and the Bond Ball Mill Work Index on SAG ground ore are measured, accurate prediction of future throughput in any SAG circuit is possible. Without knowledge of the plant T80, it can take many months to figure out how to correct what is really a SAG mill grinding problem, because that problem is hidden if the T80 is not measured. Best Practice Comminution means running a SAG mill under optimal conditions, and avoiding overloading, overspeeding and using excessive steel additions, both during the design and operating stages of the plant. When normal limits for these parameters are exceeded in the design stage, production shortfalls will result, and operating costs will be high. While extra SAG mill capacity is a bonus, lack of capacity is a disaster. This paper shows how to design workable grinding circuits on a particular ore, using either single stage SAG milling, SAB grinding, SABC grinding, or HPGR pre-crushing followed by ball milling. There are many ways to set up a SAG plant, and future expansion should always be considered at the design stage. This opportunity can be overlooked if the designer does not understand the options available.

ESTIMATING THE PROSPECTS FOR THE USE OF THE CHUPA-LOUHI FIELD CERAMIC PEGMATITE DEPOSIT WASTE DUMPS

Karelia ranks first in Russia in terms of explored reserves of traditional feldspar rocks – ceramic and mica pegmatites. A significant part of the pegmatite deposits have been worked out; some objects with estimated reserves remain in the reserve. The article provides a brief overview of the state of the quarries and dumps left after the mining of the Hetolambina and Chkalovskoe ceramic pegmatite deposits – the main sources of high-grade feldspar raw materials. The material composition of the dumps, composed of mineral fractions (quartz, mica, feldspars), which are raw materials of substandard size and quality, was assessed. A substantial part of the dumps is overburden and host rocks – amphibolites, gneisses, gabbros, gabbro-norites. We show that the chemical composition of feldspar fractions, consisting of pure microcline, microcline and plagiomicrocline pegmatite, makes them potentially suitable for the production of fine and construction ceramics, vacuum glass, high-grade technical glass, and sheet glass. The wastes from ore separation plants and the Chupa grinding and processing plant are represented by crushed material with quartz-feldspar composition. Analysis of the possibility of integrating fine-grained concentration wastes into the feedstock showed they can have a positive effect on the technological characteristics of the facing ceramic tiles production process. Rocks, industrial minerals, and waste dumps of mining enterprises of the Louhi District of the Republic of Karelia, which was included in the Russian Arctic Zone, are of interest not only as promising mineral raw materials, but also as mining and industrial heritage destinations.

DATABASE FOR NUMERICAL SIMULATION OF GAS FLOWS IN A GAS JET GRINDER

The process of material jet grinding is analyzed from the point of view of the granulometric material composition changing in the main elements of the grinding plant. A database of dependencies connecting the technological parameters of the process and the acoustic sig-nal characteristics of the mill operating zones has been created. The advantage of the ap-proach to building mathematical models and creating an automatic control system based on the developed database is the ability to accurately describe most of the factors affecting the grinding efficiency, the possibility of describing with the necessary details for specific mate-rial grinding and obtaining the required size of the ready product. The use of connections between acoustic signals and technological parameters makes it possible to take into ac-count the patterns of changes in the material particle size distribution during the passage of the flow in the grinding plant channels and respond to changes in the product quality or the grinding mode on-line, without wasting time on transport delays.

OPTIMIZING DNA EXTRACTION WITHOUT LYOPHILIZATION OR LIQUID NITROGEN GRINDINGFROM AFRICAN YAM BEAN (SPHENOSTYLIS STENOCARPA HOCHST EX. A. RICH.) HARMS TISSUES

DNA extraction is the first committed step in every molecular biological endeavour. This biomolecule can be isolated from any biological material for subsequent downstream processes. Most available protocols for nucleic acid extraction entail the use of either lyophilized tissues or liquid nitrogen in tissue grinding. These procedures pose a major limitation in the use of such protocols, especially in parts of the world where liquid nitrogen and freeze-dryer are not only expensive, but also very difficult to procure. The current study was an attempt to optimize DNA extraction procedure from African yam bean ({Sphenostylis stenocarpa Hochst ex. A. Rich.}Harms) tissues, employing the sodium dodecyl sulphate (SDS)-phenol method,without the use of lyophilization or liquid nitrogen grinding.The effect of grinding leaf tissue with acid washed sand in the protocol, phenol extraction, precipitating temperatures, ammonium acetate washing on DNA purity and yield were investigated. Spectrophotometric analysis was used to determine purity and DNA yield of extracts. The results showed that grinding plant tissue with acid-washed sand and precipitation at -20 oC significantly improved DNA yield and a single phenol treatment was sufficient for obtaining a pure extract. Comparatively, leaf was preferred to root and stem tissues for DNA extraction. The findings from this study indicated that high quality DNA could be extracted from African yam bean tissues without the costly use of liquid nitrogen or lyophilization.

DETERMINATION OF THERMOPHYSICAL PROPERTIES OF ORGANIC WASTE OF POULTRY FACTORIES

In Ukraine, poultry farming remains one of the priority sectors of the food industry in providing the population with natural protein. Scientific institutions and commercial organizations are constantly engaged in research and development of energy-efficient technologies and equipment for the disposal of organic waste generated in poultry farms to solve primarily environmental problems.The Institute of Technical Thermal Physics of the National Academy of Sciences of Ukraine (ITTF NASU) has been conducting research on compatible grinding and drying processes for a long time, as well as developing installations for heat treatment of finely dispersed labile materials. Research was carried out on drying and grinding green vegetation, clay, potatoes, bone meal, waste leather from industries, etc. Studies show the promise of using this drying method, the need to improve the design of installations for various materials, as well as the continuation of the study of heat and mass transfer processes in them. The development of these technologies also requires a thorough study of the thermophysical properties of organic waste (primarily chicken manure).The purpose of the study is to experimentally determine the thermophysical properties of the resulting chicken manure as organic waste from poultry enterprises, this will allow using the obtained values to create physical models in the study of heat and mass transfer processes in the working chambers of installations. Currently, there are a small number of publications on the determination of the thermophysical properties of chicken manure under various modes of change in its moisture content. The use of derivatographic analysis is generally not found in the literature. As a result of the experiments, the coefficients of change in the thermal conductivity of chicken manure were obtained within the temperature range from 30 to 75 ºС with a change in its humidity in the range from W=5 % to W=60 %. Using the Q-1000 derivatograph manufactured by MOM (Hungary), the change in the physical parameters of chicken manure when exposed to temperature is shown. It is shown that chicken manure is a thermostable material up to 210 ºС. When it is heated, the surface moisture first evaporates (from 40 ºС), then the bound moisture (from 150 ºС), followed by the decomposition of the organic component (from 210 ºС). From 600 ºС, the removal of the mineral component begins.In the future, the results obtained will form the basis for the development of new equipment and the creation of a methodology for engineering calculation of co-drying and grinding plants, which is the main task of further work and meets modern requirements for drying equipment.

Design of a roll crusher for sunflower stems and substantiation of the rational modes of its operation

This paper reports a study of the technological process of grinding plant residues of sunflower and the causal relationships of factors that form the system of quality indicators. The necessary prerequisites for determining rational modes and parameters of the roll crusher have been devised. A prototype of the roll crusher was designed and fabricated, in which the cutting knives are arranged along the entire width of the grip in a staggered manner, with the possibility to change the angle of inclination to the axis of drum rotation in the range of 5...20°. It was established that in the case of the right-side arrangement of the cutting edge of knives, the highest total level of the percentage of crushed stems in the range of 101‒150 mm with an additional load weighing 800 kg exceeded by 1.58 times the corresponding indicators of the roll with an additional load of 600 kg. The largest overall value of the percentage of crushed stems in the range of 0‒200 mm when additionally loading the roll with 800 kg was 1.13 times higher than the corresponding indicators of the roll with an additional load of 600 kg. In the range of 0‒200 mm, with an additional load on the roll of 600 kg, at the left-side arrangement of the cutting edge of the knives of the roll, higher total percentage of crushed stems was observed compared to the right-side arrangement. At a speed of 7.45 km/h, 13.6 km/h, the cumulative value of the percentage of crushed stems exceeded the corresponding indicators at the right-side arrangement of knives by 1.09 times, at the speed of 18.6 km/h – by 1.04 times, at the speed of 22 km/h – by 1.04 times, respectively. It has been noted that at the left-side arrangement of the cutting edge of the knives of the roll, the percentage of crushed stems in the range of 51‒100 mm, with an additional load of 600 kg, exceeded the corresponding indicators with an additional load of 800 kg. At the speed of 10.08 km/h, it was exceeded by 1.9 times; at the speed of 13.6 km/h – by 1.44 times; at the speed of 18.6 km/h – by 1.96 times; at the speed of 22 km/h – by 1.99 times, respectively

Air Pollution Associated with Total Suspended Particulate and Particulate Matter in Cement Grinding Plant in Vietnam

Air pollution associated with suspended particles has become a significant concern in Vietnam recently. The study aimed to (1) investigate dust sources; (2) measure concentration levels of Total Suspended Particulate (TSP), Particulate Matter (PM) fractions; (3) identify silica levels and the correlation with respirable particles at a cement grinding plant in Vietnam. A total of 312 samples (52 TSP, 160 PMs) at 13 processes were measured using the direct-reading dust meter. The silica composition was analyzed in a certified laboratory using the X-ray fluorescence (XRF) technique. SPSS version 26 for Window was used to analyze the data. The operations of the cement grinding plant created multiple dust sources from the jetty to the cement dispatch process. The TSP levels ranged 0.06–38.24 mg m−3, and 40.38% (n = 21) TSP samples exceeded the Permissible Exposure Limit (PEL) for an 8-h working shift. Besides that, there was a wide range and significant concentration levels of PMs in the cement processes. The levels of PMs were PM1 (0.00–0.06 mg m−3), PM2.5 (0.01–0.83 mg m−3), PM4 (0.02–4.59 mg m−3), PM7 (0.03–16.94 mg m−3), and PM10 (0.04–26.85 mg m−3). The highest mean levels of PMs factions were measured at the pre-grinding process. The inefficient operation of the dust collector contributed a significant factor to the dust dispersion in this process. The silica’s mean (SD) composition in respirable dust was 20.4% (0.86) and was not significantly different amongst the processes. There was a significant correlation between the levels of respirable dust and silica exposure in the cement grinding plant (r = 0.99). The improvement of indoor air quality is needed to prevent health effects on cement workers.