Production of complex alloy from high-silicon manganese ore and high-ash coals of Kazakhstan

The article presents theoretical and technological foundations for the production of complex alumosilicomanganese alloy (ASM) from high-silicon manganese ore, Karaganda high-ash coals and Teniz-Korzhunkol coal basins (Borly and Saryadyr coal deposits), Tekturmas deposit quartzite and long-flame coal of Shubarkol field. Based on the reference data and calculated thermodynamic data (for compounds with unknown thermodynamic data), a mathematical model of the phase structure was constructed by conducting a thermodynamic-diagram analysis of four-component Fe – Si – Al – Mn system. The compositions of alumosilicomanganese obtained from the coals of Karaganda and Teniz-Korzhunkol coal basins, in contrast to ASM alloy from Ekibastuz coals, are shifted in the region of tetrahedra with relatively large volumes. This fact indicates their increased stability and technological predictability. The results of the series of experimental tests carried out in an ore-thermal furnace has shown the possibility of obtaining an ASM alloy with controlled chemical composition using high-ash coals of Borly and Saryadyr fields, the substandard high-silica manganese ore of Zapadny Kamys field, addition of long-flame coal from Shubarkol deposit and quartzite of Tekturmas deposit to the mix by continuous slag-free process. Chemical composition of the alloy was regulated by addition of manganese ore to the sample of charge materials. A  complex alloy was obtained with the following chemical composition (%  by mass): 32  –  53  % of Si; 15.5  –  25.0  % of Al; 12  –  32  % of Mn; 8  –  20  % of Fe; 0.02  –  0.05  % of P; 0.2  –  0.5  % of C. The resulting metal does not crumble into powder when stored. This is ensured by low phosphorus content and high aluminum content of more than 10  %. Phase components of the experimental alloy were determined. The use of dumping high-ash coals, substandard manganese ores and the complete elimination of coke use ensure a low cost of the alloy. It is proposed to use this alloy for deoxidation and alloying of steel, and also as a reducing agent in the production of refined ferromanganese grades.