ANALYSIS OF THE PROCESSES OF MANGANESE STEP RESTORATIONFROM ITS DIOXIDE BY CO GAS AND GASIFICATION OF SOLID CARBONFROM THE POSITION OF THERMODYNAMICS

Abstract

The article presents the results of a thermodynamic assessment of chemical reactions of the manganese stepwise reduction from its dioxide with the reducing gas CO, as well as chemical reaction of solid carbon gasification. The purpose of the work is to determine the conditions for the occurrence of each chemical reaction and the values of their boundary (equilibrium) temperatures using expressions from literary sources and the resulting formulas for calculating the Gibbs free energy depending on temperature. Based on the thermodynamic analysis carried out, confirmed and theoretically justified the provisions on the possibility of indirect reduction reactions of Mn2O3 from MnO2, Mn3O4 from MnO2 at all temperatures of the real process in reduction furnaces by CO gas, gasification reaction of solid carbon at moderate and at high temperatures of the real process in reduction furnaces, as well as the impossibility of the indirect reduction reaction of Mn from MnO by CO gas at all temperatures of the actual process in reduction furnaces; the value of the boundary (equilibrium) reaction temperature of the gasification reaction of solid carbon was specified, which, according to the author, was 709°C; this means that the reactions of indirect stepwise reduction of MnO from MnO2 in furnace zones in which the temperature is below 709°C (according to various literature data, this temperature is 697°C or 706°C) proceed exclusively due to the residual amount of CO gas in the exhaust gases of the furnace, in hotter zones of the furnace (i.e. above 709°C) – also and due to CO gas formed by the Bell-Boudoir reaction. Considering the inconsistency of the data available in the literature and obtained in the work on the value of the boundary temperature of the reduction reaction of Mn2O3 from MnO2, as well as some discrepancy in the values of the boundary temperature of the Bell-Boudoir reaction, it is necessary to carry out a similar (using equations from the literature and obtained during the work) thermodynamic analysis of chemical reactions of the stepwise reduction of manganese from its dioxide with the reducing gas CO, as well as gasification of solid carbon by the indirect method, better known as the Ellingham method.