The expediency of involving large‐tonnage sulfur production waste from Rozdil Mining and Chemical Enterprise Sirka (Ukraine) in road surface production has been substantiated theoretically and practically. In particular, the possibility of using waste from sulfur ores flotation enrichment and sulfur filtration purification from ash and organic impurities and their mixtures in the production of modified hot mix asphalt were investigated. It was found that sulfur content changes in bitumen can influence its operational properties: at sulfur concentrations of 5 wt. %, it acts as a plasticizer and at sulfur content ≥ 20 wt. %, it behaves as a filler. There are reasons to state that it is most effective to introduce sulfur into asphalt concrete (AC) as filler aggregate directly in the preparation process of sulfur asphalt mixes in an asphalt mixer. It is shown that the strength of sulfur AC grows over time and reaches maximum values within 15 days. It has been established experimentally that the use of highly sulfur‐concentrated filler aggregates instead of traditional limestone minerals significantly improves the main operational characteristics of AC, in particular: strength at a temperature of 20°C and at a temperature of 50°C; heat resistance; bitumen content to achieve regulated residual porosity is reduced. It was demonstrated that increasing the sulfur content in filler aggregate makes it possible to reduce the bitumen content in AC. Pilot construction of road pavements was conducted, which confirmed that sulfur AC has better operational characteristics compared with regular AC.

Purpose. Research aims to study the thermodynamic patterns of coal mining waste gasification process and the formation of a theoretical basis for carbon conversion processes with the production of synthesis gas with a high hydrogen content. Methods. Thermodynamic calculations are based on the main carbon conversion reactions in the temperature range of 500-1100°C and pressures of 1-10 atm. To assess the probability of the flow of processes, the values of Gibbs energy, equilibrium constants and equilibrium conversion degree were determined, which made it possible to predict the composition of the gas phase and determine the optimal gasification conditions. The method of least squares was used to ap-proximate the obtained dependences. Findings. It has been determined that coal mining waste dumps pose a significant source of environmental hazard, since they lead to pollution of soil, water resources and atmospheric air. Traditional methods of utilization focus mainly on localization, but do not provide complete neutralization of harmful components. The conducted thermodynamic calculations confirmed the expediency of using the gasification process, which is effective at temperatures above 860°C. The autothermal nature of this process is achieved through the partial oxidation of carbon to carbon monoxide (CO), which compensates for heat loss. It has been found that increasing pressure reduces the equilibrium degree of carbon conversion. The obtained thermodynamic dependences make it possible to predict the composition of synthesis gas and, subsequently, to assess the prospects for the implementation of technologies for complex recycling of coal mining waste. Originality. For the first time, a comprehensive thermodynamic assessment of coal mining waste gasification reactions has been conducted, and thermodynamic dependences of Gibbs energy change, equilibrium constants, and equilibrium conversion degree have been obtained over a wide range of temperatures and pressures. This made it possible to determine the optimal conditions for the process flow and confirm its technological feasibility at temperatures above 860°C. Practical implications. The results of the research form a theoretical basis for creating effective technologies for complex recycling of coal mining waste to produce synthesis gas, which can serve as a promising energy source, ensuring compliance with modern principles of sustainable development and rational nature management.

As the world's population grows, the problem of food shortages becomes global, and, for human survival, it is necessary to significantly increase food production, which may increase environmental pollution. This paper has theoretically and practically substantiated the expediency of coagulation treatment of wastewater from milk-processing enterprises. The coagulant proposed to use is a multi-tonnage waste from industrial enterprises, specifically technical ferrous sulfate. It is shown that it is advisable to use the dairy effluent imitations based on milk powder for experimental studies. The potentiometric titration of dairy effluent imitations has established the presence of two points (pH=4.2 and 8.3), which characterize the boundaries of the buffering capacity of solutions. The expediency of carrying out the process of coagulation of dairy effluents in a weakly alkaline environment at pH≥8.3 has been substantiated, and, for the starting effluent to reach such a pH value, a 10-% suspension of Са(ОН)2 should be used. The effectiveness of reagent treatment of dairy effluents has been experimentally confirmed, subject to the alternate introduction of a coagulant (technical FeSO4) and flocculant (polyacrylamide) in the quantities of 120 and 40 mg/dm3, respectively; the degree of clarification of dairy effluents is 90 % while the residual COC value is 76 mgO2/dm3. It has been shown that when ultrasound was applied, it was possible to significantly reduce the interaction time and the amount of Са(ОН)2 suspension necessary to achieve pH≥8.3. Thus, there are grounds to assert the prospects for devising highly effective technology for the coagulation treatment of wastewater from milk-processing enterprises; the results and conclusions reported here about the technological feasibility of using technical FeSO4 as a coagulant could be practically applied for other technologies of coagulation wastewater treatment, provided that its pH value is brought to 8.3.

Due to the growing energy consumption and increasing share of fuels with high sulfur content in the global energy balance, there is a need for new, highly efficient methods and apparatus for recycling exhaust SO₂-containing gases. It is found that SO₂-low-concentrated gases are advisable to recycle by the liquid-oxidation method using NaOH as an intermediate absorbent and air oxygen as oxidant. Effective head apparatus – horizontal apparatus with bucket-like dispersers (HABD) is proposed for the cleaning process. To confirm the effectiveness of this apparatus in the processes of chemisorption and liquid phase oxidation of SO₂, a pilot study on enlarged laboratory setup, the head apparatus of which was a scale model of HABD is carried out. The study is conducted in a wide range of concentrations of SO₂ (0,4...34·g/Nm³) and pH of absorbing solutions (pH=3...13) using modern gas-analyzing devices. It is found that the irrigation density of 0.5 m³/Nm³ is technologically feasible. The cleaning process is appropriate to perform under counterflow motion of phases, which will allow combining chemisorption and oxidation in one HABD, provide high degrees of recovery (99.9...100 %) and liquid phase oxidation (80...99 %) of SO². Due to the high velocity of dispersed droplets of ~ 10 m/s and intensive interphase renewal, it is managed to significantly reduce the diffusion resistance in the gas phase and transfer the process to the liquid film and provide high mass transfer coefficients of 0,82·10^-4…1,80·10^-4 (Pa·s·m³). It is found that at low initial concentrations of SO₂ (0,4...7,74 g/Nm³), the process rate is limited by SO₂ diffusion, and at high (10.54...33.89 g/Nm³) - NaOH diffusion. The process under study is described by the first-order reaction equation and is characterized by high values of the process rate constant – 0.46 s^-1. Pilot studies confirm the high efficiency of HABD in the studied processes, prove the possibility of combining dust collection, chemisorption and oxidation stages in one apparatus.