Kompleksnoe Ispolzovanie Mineralnogo Syra = Complex use of mineral resources

Upcycling Chrysotile Asbestos Waste into High-Performance Wollastonite Chemisorbents for Demetallization and Desulfurization of Heavy Oil Residues

2026-10-21T07:53:55+00:00

The disposal of chrysotile asbestos waste poses significant environmental hazards, while heavy oil residues demand costly pretreatment to remove toxic metals and sulfur. This study presents a circular economy approach to convert acid-leached chrysotile asbestos waste into a functional chemisorbent for the simultaneous demetallization and desulfurization of heavy petroleum residues. Following hydrochloric acid leaching, the asbestos waste transformed into an amorphous, highly reactive silica-rich material. Through high-temperature synthesis (1100 - 1280 °C) with calcium and sodium carbonates, a wollastonite (CaSiO₃) and calcium silicate-based chemisorbent was produced. Comprehensive characterization using XRD, FTIR, TG-DTA, BET, and EPR confirmed that the synthesized material exhibits a remarkably high specific surface area (280 - 315 m²/g), substantial pore volume (1.213 cm³/g), and abundant active paramagnetic centers - far exceeding those of commercial zeolite. When tested in the thermal adsorption treatment of vacuum tar (380 - 410 °C), the chemisorbent achieved removal efficiencies of 40 - 55% for vanadium (V), nickel (Ni), and iron (Fe), along with significant sulfur reduction. These results demonstrate a viable pathway for transforming hazardous asbestos waste into a value-added adsorbent, enabling cleaner heavy oil processing and reducing both industrial waste and refinery operating costs.

The environmental efficiency of the combined combustion of low grade Ekibastuz coal and plant biomass

2026-08-24T04:41:03+00:00

This article presents the results of a study on the layered combustion of low-grade Ekibastuz coal blended with biomass additives aimed at improving the energy efficiency and environmental sustainability of small- and medium-scale energy systems. Corn waste, which is a by‑product of agro‑industrial production, was used as a bio‑additive. Comprehensive physico-chemical analysis of the original components was carried out, including determination of their calorific value. Based on the obtained data, fuel mixtures with different biomass contents were prepared, which allowed an in-depth analysis of co-combustion processes and the relationship between the proportion of biomass, the calorific value of the mixture, the combustion efficiency, and the level of pollutant emissions to be determined. The results showed that the most optimal composition is a fuel mixture with a biomass content in the range of 20-30% and coal in the range of 70-80%, providing the best combination of energy and environmental performance. Calculations and experimental studies of layered combustion parameters in installations with a fixed layer have been performed. It was demonstrated that the addition of 20–30% biomass intensifies the combustion process, increases the overall calorific value of the fuel blend, and reduces the concentration of harmful substances in flue gases compared to the combustion of pure coal. Rational process conditions have been defined, including the optimal height of the fuel layer, temperature regimes, and combustion duration. The results confirm the high prospects of using fuel mixtures based on low-grade coal and biomass as a cleaner and more sustainable solution for heat supply of small and medium-sized energy systems in Kazakhstan.

Diabase-porphyrite crushing screenings as an alternative aluminosilicate component for Portland cement clinker production

2026-07-23T06:47:58+00:00

This study evaluates the feasibility of using diabase–porphyrite crushing screenings from the Shekhjeli deposit, generated as a by-product of crushed-stone production, as an alternative aluminosilicate component in the raw meal for Portland cement clinker production. The raw materials were characterized by chemical and mineralogical analyses, and raw meal compositions were evaluated through calculation and laboratory firing. The phase composition and microstructure of the obtained clinker were examined by X-ray diffraction and SEM–EDS, while the technological and mechanical properties of the resulting cement were also determined. A three-component raw mix containing 20.73 wt.% diabase–porphyrite screenings was selected, and firing at 1420 °C resulted in the formation of the principal Portland cement clinker phases. SEM–EDS observations showed a relatively homogeneous clinker microstructure comparable to that of industrial clinker. Cement prepared from the experimental clinker exhibited normal hydration behaviour and reached a compressive strength of 39.5 MPa after 28 days of curing. These results demonstrate that diabase–porphyrite crushing screenings can serve as an alternative to the conventional clay component, contributing to the utilization of local mineral waste and expansion of the raw-material base for cement production.

Hydrodynamic Justification of the Effectiveness of Horizontal Wells for In-Situ Uranium Leaching in Low-Permeability Formations

2026-09-01T10:54:50+00:00

In-situ leaching (ISL) is the dominant method of uranium production from sandstone-hosted deposits, since its efficiency falls sharply in low-permeability ore horizons, where vertical wells create a narrow zone of hydraulic influence. This study quantifies how far a horizontal well can restore the productivity of such blocks and identifies the mechanism responsible for the gain. Steady-state Darcy flow was computed for a vertical well (Dupuit–Thiem) and for a 150 m J-shaped horizontal well (Joshi) using the parameters of Section 6–7 of the Budenovskoye deposit, Kazakhstan: kh = 1.0 mD, h = 8.0 m, kz/kx = 0.1. The vertical-well solution was calibrated against measured field flow rates from the same section. The horizontal configuration raises productivity from 0.32 to 1.95 m³/day (a factor of 6.1), expands the swept pore volume by a factor of 2.9, and lowers the Darcy velocity at the sandface by a factor of 3.1. Assuming the same characteristic transport length and reaction parameters, the lower sandface Darcy velocity increases the relative Damköhler number by a factor of 3.1, indicating a greater potential for reaction during fluid residence. The effect on uranium recovery and non-target acid consumption requires validation using a fully calibrated reactive-transport model. Blocks with k < 2 mD and h < 10 m may therefore be recoverable with J-shaped wells.

Quadratic modeling of Al₂O₃ content during hydrochloric acid activation of Navbahor bentonite

2026-09-18T05:05:33+00:00

The present paper is concerned with mathematical modeling of the change in the Al₂O₃ content in the process of the acid activation of bentonite clay using hydrochloric acid (HCl). The objective of the research was to investigate the effect of the HCl concentration on the Al₂O₃ content in the bentonite and create a mathematical model that describes the relationship between these variables. To do this, bentonite samples were activated with HCl solutions of concentrations 5, 10, 15, and 20%. The acquired data were subjected to analysis by using the quadratic polynomial regression model based on the method of least squares in OriginPro 2026. The adequacy of the model was estimated using the coefficient of determination (R²), the root means square error (RMSE), and the mean absolute error (MAE). The constructed model showed a very good fit to the experimental data (R² = 0.9646, RMSE = 0.2001, and MAE = 0.1790), but the relative error between calculated and experimental values varied from 0.73% to 2.60%. Thus, the results have shown that the suggested model could be successfully applied for the preliminary assessment of Al₂O₃ content at an intermediate concentration of HCl in the range of 5-20% and for the technological calculations. The suggested quadratic polynomial regression model is a valuable mathematical tool for the optimization of the acid activation process of bentonite, for the quantitative evaluation of the changes in Al₂O₃ content, and for the indirect assessment of the sorption properties of the clay.