THERMODYNAMIC JUSTIFICATION OF OPPORTUNITY OF USING HIGH-TEMPERATURE COMBUSTION FLANKS FOR OXIDATION OF MELT IMPURITIES IN AGGREGATES OF CONVERTER TYPE. REPORT 2. INTERACTION OF THE FLANK WITH METAL AND SLAG IN THE CONVERTER BATH

Abstract

A thermodynamic analysis of the physicochemical processes taking place in the converter bath using gas-oxygen burners for intensive bath heating was performed. In the working space of the unit, when the combustion flanks interact with the converter bath, the oxygen supplied by the burners and the natural gas, as well as the oxygen supplied through the tuyere, react in a bubbling slag and metallic emulsion, as a result of which iron and impurities are oxidized. It is established that the use of flank burners changes the composition of the gas phase in which in H2 and H2O, changing the oxidizing ability of the gas phase, are found in addition to O2 , CO, CO2 . The presence of solid carbon (for example, pulverized coal fuel) in the flank burner can control and intensify the burning process. The burning process is the most efficient in the oxidation of carbon to CO with the excess oxygen factor less than 1.0. During melt carbon oxidation at a change in the carbon activity depending on its concentration in the melt and temperature, the oxidation conditions of carbon also change. As a universal characteristic of the description of Me – O – C system equilibrium it is proposed to use the oxygen partial pressure PO2 , as well as the accompanying characteristics PCO /PCO2 and PH2 /PH2O . It is determined that the oxidation of iron can be carried out by oxygen to insignificant degree with carbon dioxide, while water vapor at temperatures of 1600 – 2000 K practically does not oxidize iron. Oxidation of carbon dissolved in the metal is carried out quite efficiently with oxygen and carbon dioxide to the concentration less than 0.1 %. The water vapor is a very poor carbon oxidant, a weak oxidant of manganese and silicon. The intensity of oxidation of oxygen dissolved in the metal of carbon increases with the increase of temperature, of silicon and manganese – decreases. The reoxidized slag with a high content of FeO oxide at temperatures above 1800 K can serve as an oxidizer for: silicon (up to Si < 2 %), manganese (Mn < 1 %), carbon (C < 1.5 %).