Dynamics of compound formation

Abstract

Purpose. To investigate the nature and dynamics of trace elementscompound formation during coal thermal treatment and to determine their distribution among the resulting products. The methods. The study is based on theoretical research using a software package for modeling multicomponent equilibrium heterogeneous systems. Findings. The article presents the results of investigating the formation of trace elementscompounds of the minor group (Li, Ba, Ge, Ti, Zr, Mo, Cu, Zn) during coal thermal treatment using air and oxygen as oxidizing agents. It was established that all minor elements, except germanium and zinc, are present both in the molten ashand in the gas phase. The temperature intervals of transition of individual trace elements into the gas phase weredetermined, showing that zinc actively volatilizes at temperatures below 1500 °C. Whereas most other minor elements reach their maximum concentrations in the gas phase at temperatures above 1500 °C. The degree of transition of trace elements into the gas phase was quantitatively determined depending on the type of oxidizer. It hasdemonstrateda significantincrease in the volatility of lithium, titanium, and copper (up to 83–90% and 64–75%) and a less intensive transition of barium and molybdenum (22–32% and 35–75%). The temperature of condensation of trace elements compounds from the gas phase into the liquid phase was identified. Thisprovideda basis for designing systems to recover trace elements from gaseous products. The originality. Further development was achieved in understanding the patterns of formation and distribution of trace elements of the minor group during the thermal treatment of coal, depending on the type of oxidizing agent and the treatment temperature.The temperature intervals and transition degrees of individual trace elements into the gas phase were determined. Theyenableda more precise characterization of their volatility and behavior during gasification. The results form a scientific foundation for optimizing technologies aimed at recovering valuable trace elements from the products of coal thermal treatment. Practical implementation. The obtained results make it possible to optimize the operating conditions of coal thermal treatment in order to enhance the extraction of valuable trace elements and reduce their losses in coal ash residues. The identified regularities of trace elements transitions into gaseous and condensed phases can be applied to improve gas-cleaningsystems and to develop technologies for comprehensive use of Ukrainian coal, thereby increasing its economic and environmental efficiency.