ANALYTICAL EXPRESSIONS FOR Fe – Si – Al – Mn METAL SYSTEM AND PHASE COMPOSITION OF ALUMOSILICOMANGANESE

Abstract

Calculations of analytical expressions of Fe – Si – Al – Mn quaternary metal system and phase compositions of complex alu­mosilicomanganese alloy are presented in the article. Analytical expressions were obtained by the derivation of transformation equations that show any secondary system through the primary components of the base system. The location of the melt given composition was determined from positive values of coefficients of the equations of certain polytope calculated by Heath equation. Chemical composition of the complex alumosilicomanganese al­loy obtained under semi-industrial conditions corresponds to the tetrahedron FeAl3 – Al – Si – Mn11Si19 with the volume equal to V = 0,216811. It was established that compositions of alumosili­comanganese obtained from coals of the Karaganda coal basin, in contrast to the AMS alloy from Ekibastuz coals, tend to be in the re­gion of tetrahedra with a relatively large volume. The alloy compo­sitions modeled by such large-volume tetrahedrons are more stable and technologically predictable. Practical application of the results of the thermodynamic-diagram analysis (TDA) to the compositions of different grades of alumosilicomanganese reduces to finding of elementary tetrahedra within which their compositions are limited, and the normative distribution of primary phases between second­ary compounds for them is equal to 100 % of the considered tetra­hedron. Based on the normative distribution of the primary phases between the compounds (secondary phases) located on vertices of the Fe – Si – Al – Mn tetrahedron, a metallurgical evaluation of the melts can be made. This will subsequently allow to determine the phase composition of metal products at smelting of various grades of alumosilicomanganese and to limit the residual content of silicon and aluminum in them while using the latter in the recovery of man­ganese from manganese ore, as well as silicon and aluminum from high-ash coal. The derived analytical expressions for estimating the type and number of secondary phases of Fe – Si – Al – Mn system formed in it are universal and can be used both at smelting of vari­ous grades of alumosilicomanganese and in assessing the composi­tions of ferrosilicoaluminum and ferrosilicomanganese.