This study investigates the effectiveness of various beneficiation methods for recovering chromium from refined ferrochrome slag. Dry magnetic separation at different field intensities (0.45 T and 0.8 T) showed that selective extraction of metallic chromium (Cr_met) is more efficient at 0.45 T, achieving a recovery rate of up to 90.05%. Pneumatic separation using SEPAIR technology demonstrated promising results, especially for wide particle size fractions (0–20 mm), where chromium recovery reached 40.32% due to density differences between slag particles and metallic inclusions. Enrichment on a shaking table proved to be the most selective method, producing a concentrate with 29.9% Cr and 90.7% recovery, although the yield was low (3.8%). SEM-EDX and SEM-BSE analyses confirmed the heterogeneous phase composition of slag grains, revealing chromium–iron alloys embedded in oxide matrices. Based on laboratory experiments and material characterization, it is concluded that magnetic separation can be used for preliminary concentration, pneumatic classification is effective for processing bulk slag with economic potential, and gravity concentration on shaking tables is suitable for producing high-grade concentrates. The resulting tailings, low in chromium, are suitable for reuse in the production of building materials after carbonation treatment.

It has been demonstrated that when a low-molecular-weight salt solution flows through a polyelectrolyte gel, an electromotive force is generated, and its polarity depends on the sign of the polyelectrolyte network’s charge. A mathematical model proving the possibility of developing a device for separating a solution of low-molecular salt into enriched and depleted phases under the influence of gravitational forces has been developed. Such a device contains a system of parallel columns filled with different kinds of cross-linked polyelectrolyte networks. The proposed mathematical model is grounded in the theory of double electrical layers forming at the hydrogel/solution interface; these layers deform under non-equilibrium conditions, specifically during the flow of the solution through the cross-linked polyelectrolyte network. An analogous model is proposed describing the case of an analogous device based on an electric current passing through two oppositely charged contacting networks, which provides the possibility of separating the initial solution into enriched and the depleted phases too. The practical applications of the found effect are discussed. In particular, it is demonstrated that a wide number of measurement electronic devices can be created on such a base, including devices to be used within the investigation of polyelectrolyte hydrogels of different types.

This study examines the surface-dependent formation of interpolymer complexes (IPCs) by the layer-by-layer (LBL) deposition method. The materials used in this analysis are poly(acrylic acid) (PAA) combined with cellulose ethers, namely methyl cellulose (MC), hydroxypropyl cellulose (HPC), and hydroxyethyl cellulose (HEC), and poloxamers PX188 and PX407. PMMA, PS, and glass surfaces have been used to study the influence of hydrophobicity and hydrophilicity on IPC growth and its properties. Through contact angle measurements, PMMA and PS were found to be hydrophobic and glass hydrophilic. It was revealed by gravimetric analysis that IPC films reveal the highest growth on PMMA substrates, followed by PS and glass. Both the molecular weight of HEC and the hydrophobicity of the surface considerably affected the growth. Hydrogen-bonded complexation was evident by means of FTIR spectroscopy, while changes in some characteristic absorption bands demonstrated the extent of interactions between polymers. Scanning electron microscopy showed that variations in the microstructure of surfaces occur; PAA-MC and poloxamer complex layers were well organized on hydrophobic substrates. Thus, the experimental results showed surface properties, especially hydrophobicity, to be important for IPC growth and structure. These findings contribute to the understanding of IPC behavior on different substrates, thus giving insights into applications in drug delivery, coatings, and functional films.

The present study is devoted to evaluating the possibility of using coal fines and waste from electrolysis production, spent anode material, as an alternative raw material for the production of metallurgical coke suitable for use in agglomeration processes. As part of the study, laboratory briquetting of raw materials, coking of the obtained briquettes, and a comprehensive study of the properties of the obtained coke were carried out. The purpose of the study was to assess the potential of processing man-made carbon-containing waste and to determine the optimal composition of the charge for coke production. A thermal analysis made it possible to establish optimal coking temperature conditions, the nature of the release of volatile components, and the features of the restructuring of the carbon matrix, which are of key importance for predicting the quality of the final product. The charge materials demonstrated high thermal stability and ensured the production of high-quality coke suitable for use in sintering processes. Measurements of electrical resistivity showed a value of 0.21 ohm· cm, indicating the high electrical conductivity of the material at low temperatures due to the peculiarities of the microstructure and phase composition of coke. Additionally, the calorific value of the briquettes was 6840.8 kcal/kg, indicating high fuel efficiency. The data obtained confirm the potential of replacing traditional high-quality coal with alternative briquetted raw materials that provide the necessary thermal energy and temperature conditions during coking. The results of the study demonstrate the possibility of effectively using spent anode material in a mixture with coal fines and coal pitch as a binding component for the production of coke suitable for use in metallurgical processes. The research supports the development of environmentally sustainable approaches to the disposal of carbon-containing industrial waste and opens prospects for their industrial use as resource-saving and environmentally oriented alternatives to traditional coke.

This study evaluates coke for iron ore sintering manufactured from Ekibastuz coal fines (fraction 0–3 mm), spent anode material (SAM) from aluminum electrolysis, and coal tar pitch. Laboratory coking was performed at 1000 °C (60 min hold), followed by sintering trials using coke containing 10 wt% and 20 wt% SAM. Microstructural (SEM/EDS) and spectral data indicate an optimal SAM range of 10–20 wt%: higher additions (≥30 wt%) lead to structural degradation of coke, accompanied by reduced mechanical integrity. The produced coke shows C = 85%, S = 0.9–1.1%, ash ≈ 19%, volatiles = 1.5–2.5%, and moisture (Wr) ≤ 1%, which is acceptable for sintering use. In sintering tests, the yield of usable sinter reached 72.4% (10 wt% SAM) and 73.5% (20 wt% SAM); impact strength was 83% and 78%, respectively. XRF of sinter showed Fe_total > 51%, CaO ≈ 5.5–6.8%, SiO₂ ≈ 6.6–7.2%, and S = 0.40–0.45%, meeting technological requirements for blast-furnace practice. Overall, using spent anode material within 10–20 wt% increases fixed-carbon content, enables valorization of aluminum industry waste, and delivers coke for agglomeration performance without compromising key chemical or mechanical indices.

В данной работе исследуется модификация битума вторичным полипропиленом с точки зрения химических взаимодействий, структурных изменений и улучшения эксплуатационных характеристик битумно-полимерной системы. Рассматриваются процессы растворения и диспергирования полимера в битумной матрице, а также влияние молекулярной структуры полипропилена на реологические, термические и механические свойства полученного композита. Описаны ключевые стадии подготовки битумно-полимерных композиций, включая термостабилизацию, гомогенизацию, определение оптимального соотношения компонентов и методы их смешивания. Проведен анализ изменений физико-химических характеристик модифицированного битума: температуры размягчения и глубины проникновения иглы при 25°C. Результаты исследования показали, что введение вторичного полипропилена способствует увеличению термостойкости, повышению вязкости и улучшению адгезионных свойств битума. Это позволяет расширить его применение в составе асфальтобетонных покрытий, улучшая их долговечность и устойчивость к климатическим факторам. Дополнительно изучены различные концентрации полимерной добавки (от 2% до 6%) и их влияние на структурные изменения битумного вяжущего. Полученные данные свидетельствуют о том, что оптимальная концентрация полипропилена обеспечивает улучшенные эксплуатационные свойства, снижая пластическую деформацию и повышая механическую прочность. Применение вторичного полипропилена позволяет не только повысить качество дорожных покрытий, но и решить проблему утилизации полимерных отходов, снижая нагрузку на окружающую среду. Это открывает перспективы для дальнейших исследований в области полимерной модификации битума и разработки более экологичных и долговечных асфальтобетонных материалов. Дополнительно рассмотрены механизмы взаимодействия полипропилена с битумной матрицей, включая влияние молекулярной массы, степени кристалличности и термической стабильности полимера. Проведен сравнительный анализ свойств битума, модифицированного различными видами вторичных полимеров, что позволило выявить наилучший вариант для применения в дорожном строительстве.