Grinding Waste Research Articles

Исследование параметров системы аспирации рельсошлифовального поезда

The rail-grinding technology is used for the railway network of the JSC RZhD to eliminate rail defects and extend the lifecycle of the railway track. In order to implement the rail-grinding technology, currently, rail-grinding trains RShP-48 are used. Rails are ground with special grinding wheels made of zirconium electro-corundum manufactured based on aluminum oxide and zirconium oxide, with bakelite organic bond as a binder. In addition, the abrasive wheel composition includes various chemical components. When an abrasive tool is destructed, grinding waste in the form of suspensions is generated during its mechanic work. The suspensions spread over long distances and negatively affect both the environment and the working conditions of the rail-grinding train maintenance personnel. Today, the company «Sinara — Transport Machines» is developing a new rail-grinding train RShP 2.0 with a pre-installed aspiration system to collect grinding wastes for further utilization. When developing the technical design of RShP 2.0, the main characteristics of the aspiration system have been determined. In order to confirm the efficiency of the obtained parameters of the aspiration system, laboratory tests have been conducted on a special rail-grinding unit. According to the results, the aspiration system with the stated technical characteristics absorbs the fine fraction of grinding products which is about 50 % of the total lost mass of the grinding wheel. Considering a large abrasive that sticks to the spark arrestors together with metal chips, the aspiration system RShP 2.0 will enable removing up to 90 % of grinding waste.

Структура та властивості нових підшипникових композитів на основі сталевих відходів для важких умов експлуатації друкарських машин

The article presents the research results on the structure and properties of new self-lubricating bearing composites based on grinding wastes of high-alloyed steel 8X4V2MFS2 with additives of CaF2 solid lubricant. The new composites are designed to operate in friction units of printing machines at rotational speeds of 600˗800 rpm and increased loads of up to 3.0 MPa. It is shown that the application of the developed technology ensures the formation of a fine-grained heterophase structure of the new composite. The formed structure is a metal matrix base made of regenerated grinding waste from 8X4V2MFS2 steel, consisting of a high-alloy α-solid solution and solid grains of alloying elements’ carbides, as well as a uniformly distributed solid lubricant CaF2. This structure ensured the formation of the new composite’s physical, mechanical and tribological properties high level. In the process of friction, antifriction films were formed on the contact surfaces, which provided a self-lubricating mode. Comparative friction and wear tests have shown significant advantages of the new waste composite compared to cast brass L63, which is traditionally used in friction units of printing equipment. The determined level of physical, mechanical, and tribological characteristics makes it possible to recommend the studied material for use in friction units of printing equipment operating at elevated rotational speeds of 600˗800 rpm and loads up to 3.0 MPa in air. The studies have shown the prospects of using a wide range of valuable metal grinding waste in the repeated production cycle for the manufacture of high-quality composites. The reuse of such waste will make a significant contribution to the protection of the environment from pollution associated with human industrial activity and will help reduce its negative effect on the ecosystem. Keywords: grinding waste, high-alloyed steel, technology, composite bearing, microstructure, solid lubricant, properties, antifriction films, printing machines.

Oxidative leaching of rhenium from grinding waste of rhenium-containing superalloys

The study investigated the feasibility of oxidative leaching rhenium in the presence of hydrochloric acid from machining waste (grinding waste) derived from products made of ZhS-32VI, a nickel-based heat-resistant alloy containing rhenium. This was achieved through agitation leaching process. The grinding waste fraction size of –0.071 mm, which accounted for the highest yield (49.2 wt.%), was utilized in the experiments. The rhenium leaching process was conducted in two variations: in the first option, grinding waste was mixed with a hydrochloric acid solution at ~100 °C, followed by the addition of hydrogen peroxide to the leaching solution after it had cooled; in the second option, leaching was performed using a hydrochloric acid solution with the gradual addition of hydrogen peroxide solution. The highest degree of rhenium leaching (91.0 %) was achieved in the first option. In this case, the initial concentration of hydrochloric acid was 8 M, and the molar ratio of the added reagents was ν(HCl): ν(H2O2) = 2.7 : 1.0. The kinetics of nickel leaching using a 6 M hydrochloric acid solution at 70 °C, with a solid-to-liquid phase ratio of 1 g : 50 ml, was also examined. The analysis of the kinetic data, processed using the “contracting sphere,” Ginstling–Brounshtein, and Kazeev–Erofeev models, indicates that the nickel leaching process occurs within the kinetic region. Additionally, the kinetics of rhenium leaching from the solid residue obtained after the hydrochloric acid leaching of nickel from grinding waste was investigated. Employing the same kinetic models to analyze the data, it was determined that the limiting stage of this process involves the diffusion of hydrogen peroxide within the rhenium-containing solid residue.

Kinetics and Optimization of Metal Leaching from Heat-Resistant Nickel Alloy Solid Wastes.

Recycling waste from the production and consumption of heat-resistant alloys to return them to production is an urgent task due to the high cost of the components contained in these alloys. The kinetics and conditions of the acid leaching process of the grinding waste of a heat-resistant nickel alloy are studied depending on the composition of the acid solution (H2SO4, HCl, HNO3, and their mixtures) at room temperature to boiling point temperature and various acid concentrations (1.5 to 3.0 mol/L), ratios of waste to solution (1:10 to 3:10), fraction sizes (0.04-1 mm), and contact duration (1 to 120 h). The linearization of experimental data by the Gray-Weddington, Gistling-Brownstein, and Kazeev-Erofeev equations showed that the rate of the leaching process was influenced by both the chemical reactions between sulfuric acid and metals included in the grinding waste and the diffusion of reagents through the film of reaction products and undissolved impurities. Optimal conditions for acid dissolution of the grinding waste have been established to obtain the maximum degree of extraction of the main component of the alloy, nickel. The processing of powder particles with a size of less than 0.1 mm should be carried out in a solution of sulfuric acid with a concentration of 3.0 mol/L at a temperature of 100 °C for 6 h with a ratio of solid to liquid phases of 1:10. The reported results are very important for industry personnel to recover metals and for environmentalists to treat the alloy waste.

Properties of high-performance concrete with automobile grinding waste as replacement of fine aggregate

Properties of high-performance concrete with automobile grinding waste as replacement of fine aggregate

Generation of Si@C/SiC@C core–shell nanoparticles by laser irradiation of silicon grinding waste

AbstractIn recent years, the demand for lithium‐ion batteries has increased because of the global focus on carbon neutrality. Silicon/carbon (Si/C) composite nanoparticles have potential for application as high‐performance anode materials in lithium‐ion batteries, which can enable the widespread use of lithium‐ion batteries or lithium‐ion capacitors and contribute toward decarbonized society. In this study, Si@C/SiC@C core–shell nanoparticles with sizes in the range of 10–40 nm were produced by pulsed laser irradiation (wavelength = 1070 nm; pulse width = 10 ms) of a mixture of graphite powder and waste Si powder discharged from the grinding process of Si wafers. High‐speed camera observations of the laser‐induced plume were conducted to elucidate the nanoparticle generation mechanism, and it was determined that Si/SiC nanoparticles were formed within the laser‐induced plume in the early stage of laser irradiation. Si and C demonstrated different plume propagation patterns and plume decay times, and the time difference enabled the coating of the generated Si/SiC nanoparticles with a thin layer of graphene, forming core–shell hybrid structures. The electron diffraction results revealed that the generated nanoparticles were mainly composed of 3C‐SiC@C core shells, which is a novel nanomaterial with promising applications as anode materials for future lithium‐ion batteries.

New Antifriction Composites for Printing Machines Based on Tool Steel Grinding Waste

In this article, we present research results on the structure and properties of new self-lubricating antifriction composites based on 4H4VMFS tool steel grinding waste with solid lubricant additives. The new composites are designed to work in the friction units of offset cylinders in printing machines at rotation speeds up to 7000 rpm and increased loads up to 5.0 MPa. The developed technology formed composites with a fine-grained heterophase structure with a metal matrix base of tool steel 4H4VMFS regenerated grinding waste, consisting of high-alloy α−solid solution and hard grains of alloying element carbides, as well as evenly distributed CaF2 antiseizure solid lubricant. This structure ensured the formation of composites with favorable functional properties. During the friction process, antiseizure films were formed on the contact surfaces, resulting in a self-lubrication mode. Comparative tests for friction and wear showed significant advantages of the new waste composite compared to cast bronze parts, which are traditionally used in the friction units of offset cylinders of rolled newspaper printing machines. The stable operation of the new composite made it possible to ensure a “wear-free” effect. Studies have shown the importance and prospects of using the wide range of valuable grinding waste in the reproduction cycle to manufacture quality composites. Reuse of such waste would significantly protect the environment from pollution connected with human activity industrial and mitigate negative impacts on ecosystems and the biosphere.

A Comparative Analysis by Experimental Investigations on Normal and Ground Ultrafine Mineral Admixtures in Arresting Permeation in High-Strength Concrete

This paper discusses the permeation characteristics of concrete made by increasing the fineness of the conventional mineral admixtures and using them as a partial substitute for cement. Silica fume and metakaolin ground to ultrafine state and ceramic powder obtained from grinding waste ceramic tiles were used as mineral admixtures. The mixes were designed for a compressive strength of 50 MPa and were prepared for both binary and ternary blended cases. Binary blended specimens were cast, partially replacing cement with unground silica fume, ground silica fume, unground metakaolin, and ground metakaolin separately in different replacement proportions. Ternary blended mixes were prepared using ceramic powder in 4%, 9%, and 14% and with silica fume in a constant level of 1% percentage. All the cast specimens were compared against the control concrete. A deeper comparative analysis was also made by comparing the performance of specimens made with unground mineral admixtures with that of ground mineral admixtures. Various parameters such as resistance against water absorption, percentage of voids, and sorptivity characteristics were studied. It was observed that increasing the fineness helps fill up the pores, thereby improving the resistance to permeation action.

Kinetics of sulfuric acid leaching of nickel from grinding waste of rhenium-containing superalloys

The paper studies the kinetics of sulfuric acid leaching of nickel, the main component of grinding waste of ZhS-32VI rheniumcontaining heat-resistant superalloy formed during mechanical processing of products and containing such impurities as abrasive materials, oils, ceramics and other contaminants with refractory metal concentration in a solid residue, in agitation mode. The nickel content is 60 %. In addition to nickel, grinding waste contains other metals such as rhenium, chromium, cobalt, tungsten, tantalum, molybdenum, hafnium, titanium, and aluminum. The process of nickel leaching from waste with a sulfuric acid solution was carried out in a thermostated cell at an elevated temperature (55–85 °С), waste : 3 M H2SO4 solution phase ratio of 1 g : 10 ml, and stirring rate of 200 min–1. Kinetics was studied using a fraction of –0.071 mm with the highest yield (49.2 wt.%) in grinding waste. Convex kinetic curves of nickel leaching from waste were obtained. It was found that when the temperature changes from 55 to 85 °С, the time until leaching stops decreases from 220 to 140 min, and nickel recovery from the solution increases from 45 to 99 %. The data of the obtained kinetic curves were linearized according to the «contracting sphere» equation, Gistling–Braunstein and Kazeev–Erofeev equations (the latter is most suitable for description). Taking into account the assessment of anamorphosis correlation coefficients, it was found that nickel leaching from grinding waste is limited by the chemical reaction, and the process proceeds in the kinetic region of the reaction. The apparent activation energy calculated using the Arrhenius equation and rate constants obtained by processing linearized kinetic curves according to the «contracting sphere» model, was 47.5±0.5 kJ/mol. This value confirms the course of the process in the kinetic region where the process can be intensified by increasing its temperature.

Structure and Properties of New Antifriction Composites Based on Tool Steel Grinding Waste

This article investigates the impact of manufacturing technology on the structure, mechanical, and tribological properties of new antifriction composite materials based on R6M5 high-speed tool steel grinding waste. The characteristics of the new composite’s structure formation and its impact on properties after use of the established technological modes, including grinding waste regeneration, were illustrated. It was demonstrated that such technology is capable of ensuring microheterogeneous structure. The material’s structure consists of the metal matrix based on R6M5 high-speed tool steel waste and uniformly distributed CaF2 solid lubricant in the steel matrix. As compared to known iron-based composites, this structure promotes a high degree of mechanical and tribological properties. During tribological tests, anti-seize thin films of 15–20 μm are formed on the contacting surfaces. These constantly renewable films contribute to the high antifriction properties of the composite under the studied friction conditions and provide a self-lubricating effect. Such films fully cover both the material’s surface and the counterface. The formation of antifriction films results in the self-lubrication mode. The findings of the study open up the possibility of predicting the friction behavior of a composite at high temperatures by selecting the initial metal grinding waste to ensure the appropriate level of properties. The extensive use of various alloy steel-based industrial grinding waste in the re-production cycle would significantly contribute to resolving the global environmental problem of protecting the environment from pollution.

ОСНОВНЫЕ НАПРАВЛЕНИЯ НАУЧНОЙ ДЕЯТЕЛЬНОСТИ СКГМИ (ГТУ) В ИССЛЕДОВАНИИ И РЕШЕНИИ ПРОБЛЕМЫ КОМПЛЕКСНОЙ И ЭКОЛОГИЧЕСКИ БЕЗОПАСНОЙ ПЕРЕРАБОТКИ ПРИРОДНОГО И ТЕХНОГЕННОГО МИНЕРАЛЬНОГО СЫРЬЯ

The result of many years research of the university scientific community in the field of topical issues of complex processing of natural and man-made mineral raw materials was the creation of a scientific school “Dynamics of working bodies of machines and equipment for fine grinding of rocks” under the leadership of Professor Dmitrak Yu. V. Research results. The dynamic parameters of the grinding bodies are determined directly in the mill grinding chamber which ensure the contactless transmission of information from the grinding ball to the receiving device. A new method of materials self-grinding and the design of a vertical centrifugal mill based on it has been developed. The mill tests during the grinding waste from the production of ceramic products (the battle of insulators, crushed mullite bricks) showed high efficiency and prospects. The tests of a laboratory vibrating mill with one grinding chamber and a rotor diameter of 250 mm for grinding dolomite were carried out. The experiments have shown the possibility of creating vibrating mills for solid materials grinding. In the development of the work of I. N. Plaksin on the flotation of ores with the jet movement of products in the scheme tested by him together with employees in the conditions of the Tekeli processing plant, the modes of joint processing of ores and gold placers were developed at the NCIMM (GTU). It was established that with the unprofitable individual development of alluvial gold mining waste, a positive economic effect can be obtained through their joint processing with ore gold reserves by fine-tuning the concentrate extracted from man-made raw materials by gravitational enrichment methods at a stationary processing plant. It is proved that the addition of the gravitational technology of alluvial gold extraction by flotation methods provides an increase in annual gold production by ~38 % due to the additional extraction of “resistant” forms of gold for gravitational methods. It has been proved in laboratory conditions that the waste slag of the Copper plant of “Ltd. MMP Norilsk Nickel” can be disposed of by joint processing with the ore of current production. It is established that the technology development using metal leaching is promising for the development of Sadonsky plant deposits.

STRUCTURE AND TRIBOTECHNICAL PROPERTIES OF COMPOSITE ANTIFRICTION MATERIALS BASED ON R7M2F6 STEEL WASTE

Background. Development of the technological measures for creating new antifriction composite materials based on waste powders of steel P7M2F6 with solid lubricant CaF2, intended for operation at temperatures up to 600 °C, sliding speeds up to 1 m/s, loads up to 5.0 MPa in air.Objective. The purpose of the paper is to determine the features of structure formation and their influence on the properties of composite antifriction materials based on industrial grinding waste of steel P7M2F6 with solid lubricant CaF2 for operation at high temperature friction units in air.Methods. Methodology consisted of the development of the regeneration technological modes of the industrial grinding waste of steel P7M2F6, determination of technological manufacturing operations for new antifriction composites that include mixing of steel powders with solid lubricant, pressing and sintering of composites. The study of the structure formation processes and properties of materials was carried out using optical and electron microscopy methods, standard methods for determining mechanical properties and tests for friction and wear.Results. The influence of the developed manufacturing technology on the formation of the structure, physical mechanical and tribotechnical properties of materials based on steel P7M2F6 grinding waste with solid lubricant CaF2 additives was determined and grounded; resulting is the formation of complex heterogeneous antifriction material with high functional characteristics. The new material’s structure formation and its influence on the functional properties after using the developed manufacture modes was shown. Micro-X-ray spectral analysis confirmed the fact that CaF2, the contact pair’s chemical elements and oxygen form an antifriction film that provides a self-lubrication mode at the determined friction temperatures.Conclusions. The possibility of predicting the structure and functional properties of antifriction self-lubricating composite materials at high temperatures by purposeful choice of starting metal grinding wastes for certain operation conditions of contact pair was shown.

Upcycling strategy of grinding swarf by supersolidus liquid phase sintering

Abstract Machining is an important process in the metalworking industry. All machining operations, like milling, turning or grinding, generate large amounts of waste products. Due to the limited resources, it is necessary to find a working recycling strategy and to close the loop in the circular economy. However, there is no recycling strategy for grinding waste. This could be explained by the composition of the grinding waste, called grinding sludge. Therefore, this research deals with the upcycling of the grinding swarf in a PM process. The grinding swarf are characterized by SEM and XRD and processed by a ball mill treatment and a Supersolidus liquid phase sintering process.

Tribotechnical Properties of Composite Materials Produced from ShKh15SG Steel Grinding Waste

The structure and antifriction properties acquired by a new composite produced from ShKh15SG structural steel grinding waste with additions of CaF2 solid lubricant are examined. The material is intended to operate at 300–400°C under loads of 5.0–7.0 MPa in air. Analysis of the secondary structures and antifriction properties shows that contact surfaces of the test material and counterface are covered with continuous antiseize friction films in the operating conditions in question. They contain chemical elements of both the composite and the counterface, as well as calcium fluoride. Oxygen is also present in the friction films as it participates in their development, entering into chemical reactions with the contacting elements to form various oxides and promote oxidative wear. The antifriction ShKh15SG + 5.0–7.0% CaF2 composite can be effectively used in friction units intended to operate in self-lubrication conditions at 300–400°C under loads of 5.0–7.0 MPa in air. In these operating conditions, the wear rate of the self-lubricating films that form on friction surfaces is balanced by their recovery rate. This is confirmed by high tribological properties. Recovered industrial grinding waste of structural steels is shown to be promising as a metal matrix to make high-quality antifriction composites for specific operating conditions. The structure and properties of the composites can be controlled by choosing the chemical composition of grinding waste and applying optimized manufacturing modes.

Strength behavior of alkaline activated eggshell powder and flyash geopolymer cured at ambient temperature

The eggshell powder (ESP) rich in calcium content is a poultry waste product, generated from grinding waste eggshells. Flyash (FA) is an industrial waste product, generated from the combustion of coal in power plants. Currently, disposal of these kinds of waste products is a global concern. Utilization of waste products as a sustainable construction material can solve many problems related to disposal. The current study aims to determine the possibility of utilization of calcium-rich eggshell powder and industrial waste flyash through geopolymerization, to give a sustainable construction material. Mixtures of sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) with fixed 10 M concentration were used as an alkaline activator solution. Modified Proctor test, unconfined compressive strength, and split tensile strength test were performed to analyze the behavior of mechanical strength. Three precursor ratios (ESP:FA) – 30:70, 50:50, and 70:30 and three activator ratios (Na2SiO3/NaOH) – 0.5, 1, and 2 were adopted. The geopolymer composites were cured at ambient temperature (25 ± 2 °C) for 7 days, 28 days, and 56 days to assess the long term strength development. Geopolymer composite 50ESP:50FA with activator ratio 2 was found optimum for unconfined compressive strength and split tensile strength. The optimum composites found in the research have the potential to be employed in sub-base/subgrade application as a sustainable construction material made from waste-by-product.

The Functional Properties Acquired by Antifriction Composites Produced from Silumin Grinding Waste

The paper analyzes how the antifriction composites produced from AK12MMgN silumin grinding waste with MoS2 solid lubricant additions acquire their structure and porosity. The materials are intended to perform in friction joints at elevated loads of 2.0–4.0 MPa and sliding velocities of 1.0−3.0 m/s in air. It is shown how the process developed for producing these materials influences their structure and tribotechnical properties. The distribution of MoS2 in the AK12MMgN-matrix composite, its role in the self-lubrication mechanism, and the distribution of MoS2 and chemical elements of the friction joint in the contact zone in the sliding friction conditions corresponding to actual operation of joints in a printing machine are studied. The solid lubricant is uniformly distributed over the friction surfaces and thus covers the entire friction zone in the friction process. The tribological films formed in the presence of a MoS2 solid lubricant promote high antifriction properties of the composite produced from silumin waste. These properties allow the operational conditions to be improved and extend the application of new wear-resistant materials produced from recycled materials in contact joints of printing machines.

Features of Structure Formation and Properties of Com¬posite Antifriction Materials for Printing Machines Based on Recovered Wastes

Background. Development of the technological measures for creating new antifriction composite materials based on industrial grinding waste of steel 2Х6В8М2К7 with solid lubricant CaF 2 , and also the technological possibilities expansion of using a wider range of valuable secondary raw materials for the synthesis of qualitative structural materials. Objective. The aim of the paper is to determine the features of structure formation and their influence on the properties of composite antifriction materials based on industrial grinding waste of steel 2Х6В8М2К7 with solid lubricant CaF 2 designed for the printing machine’s friction unit in conditions of self-lubrication at speeds up to 750 rpm and loads up to 8.0 MPa in the air. Methods. Development of the recovery technological modes of the industrial grinding waste of steel 2Х6В8М2К7; determination of technological manufacturing operations for new antifriction composites that include mixing of steel powders with solid lubricant, pressing and sintering of composites. The study of the structure formation processes and properties of materials was carried out using optical and electron microscopy methods, standard methods for determining mechanical properties and tests for friction and wear. Results. The influence of the developed manufacturing technology on the structure formation, physicomechanical and tribotechnical properties of materials based on steel 2Х6В8М2К7 grinding waste with solid lubricant CaF 2 was determined and grounded, resulting in the formation of complex heterogeneous antifriction material with high functional characteristics. Conclusions. The possibility to control the structure and functional properties of composite antifriction materials based on steel 2Х6В8М2К7 grinding waste with solid lubricant CaF 2 for the printing machines’ parts by technological means, selecting the appropriate mark of metal grinding waste depending on the purpose of the part, the solid lubricant quantitative variations, and to apply rational manufacturing technological modes for obtaining a predetermined structure and predicted level of functional properties are grounded.

Analysis of the properties of antifriction composites based on aluminum alloy's grinding waste

We developed antifriction composites based on regenerated grinding waste of AM4.5Kd aluminum alloy with the addition of МоS2 solid lubricant intended for work in contact pairs of post-printing machines, such as folder-gluing machines and machines for pasting elements into packaging.Analysis of the structure of the new composite showed that alloying elements of the metal base form strengthening phases, which are evenly distributed in the matrix without segregation clusters. This contributes to an increase in structural strength. Molybdenum disulfide provides the effect of self-lubrication of a contact pair during operation, which causes a reduction in a friction coefficient and a wear rate compared to composite material without solid oil. Structural studies showed uniform distribution of solid oil in the entire volume of the composite, which provides an increase in tribotechnical characteristics due to formation of protective anti-gripping friction films at operation of a part of a complex shape under self-lubricating conditions.The analysis of functional properties makes possible to recommend antifriction composite made on the basis of industrial grinding waste of AM4.5Kd aluminum alloy with impurities of solid lubricant ‒ МоS2 molybdenum disulfide for parts of complex compound joints, which operate at increased discrete sliding speeds and loads without lubrication with liquid oil in the air atmosphere.Tribotechnical tests showed that the new composite wear-resistant material obtained by the developed manufacturing technology gives possibility to force maximum permissible loading modes and sliding operation rates with the consistently high antifriction properties of new composite friction parts of post-printing machines

Recovery and reutilization of high-quality boron carbide from sapphire wafer grinding-waste

Considerable amounts of high-quality boron carbide (B4C) are discarded as J240 sapphire-wafer grinding waste (J240-W), which can be mostly recovered and reutilized after purification for environmental protection. This paper has developed a feasibility method that simultaneously removes the alumina (Al2O3) and iron (Fe) impurities from J240-W with microwave-assisted acid leaching strategy. The influence factors on the Al2O3 leaching ratio, such as leaching temperature, sulfuric acid concentration, liquid-solid ratio and time, have been investigated and optimized. For comparison, the leaching of Al2O3 with conventional and ultrasound-assisted methods has also been performed. The result indicates that the Al2O3 leaching ratio at 80 °C with microwave assistance is 68.95%, much higher than that of conventional (23.66%) and ultrasound (53.13%) methods. Attributed to the unique heating mode of microwave, the Al2O3 leaching ratio can rise to 95.28% at optimum condition, while the content of purified B4C can reach to 98.22% with the residual Al2O3 and Fe fall to 0.26% and 0.12%, respectively. The recovered B4C with high purity and suitable particle size can be reutilized to manufacture W5 abrasive and W0.5 armor material, which is beneficial for environmental protection and resources reutilization.

Preparation and formation mechanism of monodisperse micaceous iron oxide from iron chromium grinding waste

The aim of this study is to develop a new method for the preparation of high-value, environmentally friendly products from iron chromium grinding waste (ICGW). Using iron‑chromium hydroxide precursors from the wet treatment of ICGW as raw material, monodisperse micaceous iron oxide (MIO) has been prepared via hydrothermal method. The effect of NaOH concentration and hydrothermal reaction temperature on the formation and morphology of obtained MIO powders were investigated carefully. Synthesized MIO powders have high purity (97.6%), even distribution of sizes (~15 μm) and uniform flake. Quality test results showed that MIO products met the first rank criterion of ISO 10601-2007 (the standards of MIO pigments for paints). Furthermore, the formation mechanism of MIO from iron‑chromium hydroxide precursors was discussed.