IMPROVEMENT OF DEEP PROCESSING TECHNIQUES FOR WASTE OF STEEL-MELTING PRODUCTION. PART 1. THERMODYNAMIC ANALYSIS

Abstract

The problem of using dump slag in steelmaking production as an industrial source of metallurgical raw materials still has no practical decision and it demands new approaches and ideas. Disposal of slag can be organized so that the result is not only building materials, but metal, suitable for further processing and use in recent years are shown. The purpose of the current work is theoretical study of opportunity and feasibility of steel-melting slag recovery processing to receive metal and oxide phases, which can be used in metallurgy and construction industry. The object of the experimental study was the slag from slag dumps of Zlatoust metallurgical plant (Russian Federation). The programming complex “FactSage” (version 6.4) was used for thermodynamic modeling of the recovery processes of slag dumps. Slag recovery of three diff erent compositions with diff erent content of FeO (15, 10 and 5 wt.%) was modeled. Modeling was performed for the temperature range of 750–1650 °C in step of 5 °C at the pressure gas phase, equal to 0.1 MPa. Excessive amounts of carbon were introduced into the system as a reducing agent in the modeling. The main results of the calculations carried-out for convenience of the analysis are shown in the form of dependences of various characte ristics on temperature. The modeling results show in particular that at temperatures above 1340 °C the iron is recovered and goes into the composition of the melt almost completely. Nickel and copper behave similarly. Total recovery of manganese in the composition of the molten metal during the recovery with carbon will not happen. An app reciable amount of manganese remains in the slag composition and gas even at maximum extraction of manganese in the metal. Assessment of the volumes of gaseous substances formed in the process of recovery at diff erent temperatures was carried out. The modeling results indicate that carbon monoxide will dominate the gas phase composition in all the temperature range. Information about the enthalpy change of the system depending on temperature was obtained and allows to assess the costs of thermal energy required to bring the system to the state in which recovery processes become possible.