Search Results (13)

Chromium pollution has emerged as a critical environmental concern, prompting extensive research into the chemical and mineralogical properties of refined ferrochrome (RFC) slag, the leaching of chromium using sulfuric acid, and the adsorption of chromium cations onto natural zeolite. The aim of the study is to analyze the chemical and mineralogical properties of purified ferrochrome slag (RFC) from the Aktobe Ferroalloy Plant and its leaching with sulfuric acid, as well as to study the effectiveness of Shankanai zeolite in the adsorption of chromium cations from a sulfuric acid solution to improve waste management in the ferrochrome industry. Semi-quantitative X-ray analysis reveals that the dominant phase in RFC slag is olivine (50.7% Ca₂SiO₄). The optimal chromium transition rate (16.67%) occurs in dilute H₂SO₄ (23%) after 145 min of leaching, while the highest transition efficiency (18.0–18.5%) is achieved at 90 °C with a leaching duration of 145–180 min. Chromium in the RFC slag cake is predominantly in the divalent state, existing as pentahydrate chromium (II) sulfate (CrSO₄•5H₂O). The chromium sorption process was studied in a sulfuric acid solution obtained after leaching of ferrochrome slags. The process of chromium sorption by Shankanai zeolite from sulfuric acid has been studied for the first time, and the influence of the main technological parameters of the process on the degree of its purification has been established. It was determined that the highest degree of purification of a chromium-containing sulfuric acid solution is achieved with a ratio of zeolite:chromium-containing sulfuric acid solution equal to 1:10, heated to 35 °C for 15 min, and it reaches (63.6–69.0%). The natural zeolite of the Shankanai deposit is an effective, and inexpensive sorbent for cleaning aggressive media, particularly media contaminated with chromium-containing sulfuric acid. X-ray diffraction analysis further confirmed that both chromium and sulfur ions participate in the sorption process, as evidenced by microstructural changes in the zeolite, including pore filling and smoothing observed in microphotographs. These findings underscore the potential of natural zeolite as an efficient and cost-effective adsorbent for the remediation of chromium-contaminated solutions following sulfuric acid leaching. Its ability to adsorb chromium ions highlights its significant applicability in environmental cleanup efforts. This study contributes to sustainability by offering an environmentally friendly and cost-effective method for chromium removal, reducing industrial waste impact and promoting circular economy principles by utilizing natural zeolite, a readily available and recyclable adsorbent. Full article

The paper presents the results of industrial research and numerical simulations of the chemical homogenization of liquid steel. The research object was a ladle furnace with a working capacity of the ladle of 100 t at the steel plant of Huta Częstochowa, currently Liberty Częstochowa Sp. z o.o. Industrial research was carried out under standard production conditions of the steelworks. The research included automatic steel sampling, measurement of the bath temperature, controlled measurement of argon flow at a given intensity, and the determination of the concentration of elements in steel samples using a spectrometric analyser. The element introduced in the form of a ferroalloy (FeMn and FeSiMn) played the role of a marker in the study of changes in the chemical composition during the process of dissolution and mixing of the alloying additive. Monitoring changes in the chemical composition of steel after the introduction of the marker was carried out by taking metal samples. The initial and boundary parameters of the modelled processes necessary to perform numerical simulations were determined successively through industrial measurements or determined on the basis of empirical relationships. A two-equation k-ε turbulence model was used to assess the flow inside the tested ladle furnace, and a discrete phase model was used to model gas bubbles. The mixing characteristics of the steel bath after introducing the alloying additive to it were determined. The comparison of the results of numerical simulations with experimental data was based on the analysis of the chemical homogenization process. Full article

This article provides information on the processing of chromium-containing waste from the Aktobe ferroalloy compounds plant using chemical reagents followed by high-temperature heat treatment for the synthesis of a composite chromite pigment used in the textile industry. This technology was developed for the first time for the purpose of recycling industrial waste and rational use of natural resources. The obtained pigments were analyzed by the X-ray phase of a D878-PC75-17.0 incident beam monochromator and the phase composition of the composite chromite pigment was studied. The thermogravimetric analysis of the composite chromite pigments was performed using a TGA/DSC 1HT/319 analyzer to determine the change in mass with time and temperature. According to the TGA results, the mass loss was determined to be 0.18% of the total mass. The elemental composition of the composite chromite pigment was determined using a JEOL JSM-6490 LV SEM device and the content of chromium oxide (Cr₂O₃) was determined, which reached up to 50%. The thermodynamic patterns of the processes occurring during the production of chromite pigments were studied using the integrated Chemistry software pack HSC-6. The results of testing printed and processed cotton and composite fabrics by the proposed method showed that the color fastness to washing and wet and dry friction is 4 points and the wear resistance assessment is 4860 and 6485 cycles, respectively. Composite chromite pigment based on technogenic wastes is recommended for use in various coloring compositions, including those used for printing on cotton and composite fabrics. Full article

The article presents the findings of a study conducted on a range of microsilicon grades selected at the Bratsk Ferroalloy Plant. The following analytical techniques were employed: X-ray fluorescence analysis, X-ray diffraction analysis, a granulometric composition study, and pozzolanic properties. The grades of the investigated microsilicon are compared with the furnace grade and the grade of the produced ferrosilicon. The findings of the research conducted at the Bratsk Ferroalloy Plant indicate that the microsilicon produced at the facility is suitable for use as an additive in the production of tires, artificial irregularities, and other rubber products intended for use on roads. In such applications, the quality and durability of the material are determined by its ability to withstand abrasion and wear. Therefore, it is essential to utilize the purest, most amorphous, and most finely dispersed silicon dioxide. The gas cleaning device GCD-4 FeSi-75 exhibits the greatest number of these parameters among the samples presented. Different samples of microsilica have a color from white to dark gray. The chemical and granulometric compositions were determined. The pozzolan activity was investigated. Based on the conducted analyses, it is possible to draw conclusions about the properties of materials and the potential for use in the construction industry for concretes of various values. The results of the analyses indicate that silicon dioxide with GCD-4 FeSi-75 is suitable for use in critical concrete structures. The quality of the silicon dioxide with GCD-4 FeSi-75 can be compared with that of Elkem 971. It is recommended that all the studied samples be employed as modifiers for cast iron, with the GCD-4 FeSi-75 sample being the optimal choice for testing in steels. The utilization of this modifier enables a reduction in the consumption of FeSi, exerting both an alloying and modifying effect on the melt. However, it is essential to emphasize the necessity for technological selection of the method of administration, as the powder, in its pure form, is susceptible to combustion and is not readily digestible. The quality of such a modifier, with a stable guaranteed effect, is comparable to the use of FeSi. Silicon dioxide plays an essential role in the production of refractories. The primary criteria for this industry are purity, the minimum content of the crystalline phase, and the activity of the material. It is recommended that the material from GCD-4 FeSi-75 be used in the production of refractories. Full article

The performance and quality of steel products are significantly impacted by the alloying element control. The efficiency of alloy utilization in the steelmaking process was directly related to element yield. This study analyses the factors that influence the yield of elements in the steelmaking process using correlation analysis. A yield prediction model was developed using a t-distributed stochastic neighbor embedding (t-SNE) algorithm, a whale optimization algorithm (WOA), and a long short-term memory (LSTM) neural network. The t-SNE algorithm was used to reduce the dimensionality of the original data, while the WOA optimization algorithm was employed to optimize the hyperparameters of the LSTM neural network. The t-SNE-WOA-LSTM model accurately predicted the yield of Mn and Si elements with hit rates of 71.67%, 96.67%, and 99.17% and 57.50%, 89.17%, and 97.50%, respectively, falling within the error range of ±1%, ±2%, and ±3% for Mn and ±1%, ±3%, and ±5% for Si. The results demonstrate that the t-SNE-WOA-LSTM model outperforms the backpropagation (BP), LSTM, and WOA-LSTM models in terms of prediction accuracy. The model was applied to actual production in a Chinese plant. The actual performance of the industrial application is within a ±3% error range, with an accuracy of 100%. Furthermore, the elemental yield predicted by the model and then added the ferroalloys resulted in a reduction in the elemental content of the product by 0.017%. The model enables accurate prediction of alloying element yields and was effectively applied in industrial production. Full article

Considering the pivotal role of ferroalloys in the steel industry and the escalating global emphasis on sustainability (e.g., zero emissions and carbon neutrality), the demand for ferroalloys is anticipated to increase. However, the electric arc furnace (EAF) of ferroalloy plants generates substantial amounts of nitrogen oxides (NOx) because of the high-temperature combustion processes. Despite the substantial contributions of many studies on NOx prediction from various industrial facilities, there is a lack of studies considering the environmental condition of the EAF in ferroalloy plants. Therefore, this study presents a deep learning model for predicting NOx emissions from ferroalloy plants and further can provide guidelines for predicting NOx in industrial sites equipped with electric furnaces. In this study, we collected various historical data from the manufacturing execution system of electric furnaces and exhaust gas systems to develop a prediction model. Additionally, an interpretable artificial intelligence method was employed to track the effects of each variable on the NOx emissions. The proposed prediction model can provide decision support to reduce NOx emissions. Furthermore, the interpretation of the model contributes to a better understanding of the factors influencing NOx emissions and the development of effective strategies for emission reduction in ferroalloys EAF plants. Full article

The integration of nanotechnology across various industries has significantly enhanced product quality and manufacturing technologies for diverse materials. Within the construction sector, the adoption of nanomaterials has sparked the advent of innovative construction methods. Extensive studies have been conducted on various nanomaterials, particularly micro- and nanosilica, exploring their use as partial substitutes for cement in concrete formulations. This study aimed to furnish a comprehensive overview of silica’s impact on concrete properties in civil engineering and road construction. Environmental concerns and potential hazards necessitate the development of strategies for managing industrial by-products. Metallurgical processes generate several such by-products, among which is silica fume—a residue from smelting in the silicon and ferrosilicon industries. Waste silica dust and slurries have proven highly effective in creating high-strength, high-performance concrete. The study presents a literature review focusing on micro- and nanosilica derived from production waste at ferroalloy and silicon plants. It includes a comparative analysis of the primary characteristics of microsilica from various sources and examines the extensive use of microsilica as a modifying additive in building materials. Analyzing different concrete compositions with and without fumed silica determined the ranges of results for each indicator. The incorporation of micro- and nanosilica into the concrete mix demonstrated its efficacy. The morphology of waste silica particles, characterized by the smooth and spherical surfaces of micro- and nanosilica particles, significantly influences the workability properties of the concrete. Full article

Prolonged development of ore deposits, ore beneficiation and metallurgical smelting of concentrates result in the accumulation of wastes, forming large-scale dumps and sludge ponds negatively affecting the environment and human health. The creation and introduction of industrial waste treatment technologies will make it possible to dispose of them with the production of valuable commercial products and improve the environmental situation. In a research article on chemical beneficiation with the subsequent gravitational beneficiation of chrome-containing slurry tailings of Donskoy Ore-Mining and Beneficiation Plant (DOMBP), which processes chrome ore of the Kempirsay deposit in the Republic of Kazakhstan, Aktobe region, having considerable stocks of such waste is presented. The chromium-containing slurry tailings were heat-treated at 1100 °C, sintered with ammonium sulfate, water and sulfuric acid in a defined ratio at 300 °C, and then the resulting sinter was leached with water at 90 °C. The cake was washed to separate the liquid part from the solid part. The solid precipitate is the chromium-containing cake, which is upgraded by gravity concentration to a grade concentrate for ferroalloy production. When the solution is evaporated, magnesium sulfate with ammonium sulfate forms the Tutton’s salt ammoshenite. High-throughput chromium oxide extraction of 93.9% was achieved as a result of the research, and three products were obtained: (1) standard chromium concentrate with 49.48% Cr₂O₃ content, (2) ammoshenite used as a nitrogen–magnesium fertilizer and (3) forsterite, which is concentrated in gravity concentration tailings and can be used in the production of refractory minerals. Full article

Renewable reductants are intended to significantly reduce CO${}_2$ emissions from ferro-alloy production, e.g., by up to 80% in 2050 in Norway. However, charcoals provide inferior properties compared to fossil fuel-based reductants, which can hamper large replacement ratios. Therefore, conditioning routes from coal beneficiation was investigated to improve the inferior properties of charcoal, such as mechanical strength, volatile matter, CO${}_2$ reactivity and mineral matter content. To evaluate the global warming potential of renewable reductants, the CO${}_2$ emissions of upgraded charcoal were estimated by using a simplified life cycle assessment, focusing on the additional emissions by the energy demand, required chemicals and mass loss for each process stage. The combination of ash removal, briquetting and high-temperature treatment can provide a renewable coke with superior properties compared to charcoal, but concomitantly decrease the available biomass potential by up to 40%, increasing the CO${}_2$-based global warming potential of industrial produced charcoal to ≈500 kg CO${}_2$-eq. t${}^{-1}$ FC. Based on our assumptions, CO${}_2$ emissions from fossil fuel-based reductants can be reduced by up to 85%. A key to minimizing energy or material losses is to combine the pyrolysis and post-treatment processes of renewable reductants to upgrade industrial charcoal on-site at the metallurgical plant. Briquetting showed the largest additional global warming potential from the investigated process routes, whereas the high temperature treatment requires a renewable energy source to be sustainable. Full article

The former manganese ferroalloy plant and the remaining tailings are affecting the quality of the environment in Šibenik Bay, Croatia, even though industrial activities ceased more than 25 years ago. This study has revealed that the main manganese mineral phases present in the recently collected tailings, as well as in the dust collected on the roof of the plant during the production period, are bustamite and Mn-oxides. The same type of Mn mineral phases was also found in recently collected sediments from Šibenik Bay. Detailed chemical and phase analyses (XRD, BCR sequential analysis, aqua regia and lithium borate fusion) of the dust sample revealed high manganese values (24.1%), while granulometric analysis showed that 50% of the particles are smaller than PM_2.5. The influence of the tailings is visible in the sediment, but the concentrations of the potentially toxic elements determined by the sequential BCR analysis are within the legal limits. Some higher values (20.3 g/kg Mn, 595 mg/kg Pb and 494 mg/kg Zn) are detected in the tailings, which are still exposed to weathering and as such should be additionally monitored. On the other hand, this material contains a considerable number of elements that could be considered lucrative (∑ REE up to 700 mg/kg, Mn up to 23 g/kg, Fe up to 37 g/kg and Al up to 25 g/kg), opening the possibility of reuse and recovery. Full article

The world’s rapidly growing demand for raw manganese has made it increasingly important to develop methods for the economic recovery of manganese from secondary sources. The current study aims to present possible ways for the recycling and reuse of silico-manganese slag landfilled in Tulcea, City on the Danube River close to the Danube Delta Biosphere Reserve in order to save the natural resources raw of manganese. In the last three decades, the ferroalloy production plant has over 2.6 million tons of slag. Slag dumping constitutes a significant source of air, water and soil pollution, which adversely affects the environment and human health. Mn present in the slag dump is an environmental pollutant with potentially toxic effects. The results obtained with a leaching method to recover manganese from slag shows two efficient ways to valorize manganese from solid fraction (54%) with size particles between 80 and 315 µm and/or reuse the leaching medium (56% Mn) with a slag size of <80 µm. The motivation of our research is the possibility to recover manganese from slag by saving natural resources of raw of manganese and the remaining fraction can be used as aggregate sources (construction and road rehabilitation by saving extract mineral aggregates and agriculture), in order to decommission the slag dump. The proposed research is in concordance with the sustainable use of natural resources for the achievement of sustainable development of the 2030 Agenda and Waste Management Legislation due of the huge ecological costs regarding non-conforming waste dumping. If we consider the cost-benefit analysis, the environmental future is more important the human health and the benefits on the quality of the population’s health and the environment which are not non-measurable in monetary value. Full article

Background: It is difficult to assess workers’ exposure to ultrafine particles (UFP) due to the lack of personal sampling equipment available for this particle fraction. The logbook method has been proposed as a general method for exposure assessment. This method measures the time and concentration components of the time-weighted average concentration separately and could be suitable for investigation of UFP exposure. Objectives: In this study, we have assessed workers’ exposure to UFP in a ferrosilicon plant. The main tasks of the furnace workers were identified, and the logbook method was used in combination with stationary measurements of UFP taken as close to the identified task areas as possible. In order to verify the results, respirable particles were collected using stationary sampling in close proximity to the UFP measuring instrument, and personal full-shift sampling of respirable particles was performed simultaneously. Thus, exposure to respirable particles determined using the logbook method could be compared to the results of standard measurement. Methods: The particle number concentration of ultrafine particles was determined using a NanoScan SMPS. Respirable particle concentration and exposure were determined using a sampling train consisting of a pump, filter, filter cassettes, and SKC Cyclone for the respirable fraction. Attendance times for workers at each work location were registered via thorough observations made by the research team. Results: The logbook method for exposure estimation based on stationary sampling equipment made it possible to calculate UFP exposure for workers operating the furnaces at a ferrosilicon plant. The mid-size furnace and the large furnace were evaluated separately. The workers operating the largest furnace were exposed to 1.47 × 10⁴ particles/cm³, while workers operating the mid-size furnace were exposed to 2.06 × 10⁴ particles/cm³, with a mean of 1.74 × 10⁴ particles/cm³. Substantial contributions from the casting area, ladle transport corridor, and both tapping areas were made. Exposure to respirable particles was 2.04 mg/m³ (logbook); 2.26 mg/m³ (personal sampling) for workers operating the large-sized furnace, 3.24 mg/m³ (logbook); 2.44 mg/m³ (personal sampling) for workers operating the medium-sized furnace, and 2.57 mg/m³ (logbook); 2.53 mg/m³(personal sampling) on average of all tappers. The average ratio of these two methods’ results was 1.02, which indicates that the logbook method could be used as a substitute for personal sampling when it is not possible to perform personal sampling, at least within this industry. Conclusions: The logbook method is a useful supplement for exposure assessment of UFP, able to identify the most polluted areas of the workplace and the contribution of different work tasks to the total exposure of workers, enabling companies to take action to reduce exposure. Full article

The renewable energy revolution calls for high-performing materials and makes metallic compounds like lithium, cobalt, nickel and vanadium more and more critical. Innovations contribute to inventions and developments like vanadium redox flow batteries for large-scale energy storage systems with numerous technological advantages. Potential shortages of vanadium and its sources will contribute to turbulence in vanadium pricing. Nowadays, main sources and production sites of vanadium are located in Russia, China and South Africa. About 85% of vanadium applications are ferroalloys and high-performance alloys, which make production and price of vanadium dependent on the iron ore market. Partial covering of a potential vanadium demand may be achieved by an exploitation of lead vanadate ore deposits as alternative vanadium source. In the present work, the processing of a lead vanadate ore, mainly containing vanadinite and descloizite was investigated. Based on ore characterizations and preliminary beneficiation tests, a flowsheet was developed to design a small-scale processing plant, including comminution, dewatering and gravity separation. Preliminary laboratory tests and samples from the small-scale processing plant show promising results for the recovery of vanadium in a lead vanadate concentrate with a grade of 12 to 16% V₂O₅ and a recovery of 68 to 75%. Full article