Thermodynamic Behavior of Some Metals Contained in Steelmaking Residues When Recycled in the Blast Furnace Part I: Potassium, Sodium and Zinc

摘要

The experience, accumulated along the years, about the behavior of volatile elements and compounds inside the blast furnace, is based on the chemical form they are found in nature, that is, zinc, potassium and sodium silicates. In order to recycle steelmaking residues containing zinc and, eventually, potassium and sodium, a new analysis about the behavior of such elements must be done, since they are found, in the residues, in form of oxides. After a thermodynamic analysis of these oxides, and comparing the results obtained when charging them in the form of silicates, it is possible to conclude that, concerning to zinc, the high content of this element in steelmaking residues is not a problem for recycling them in the blast furnace. Regarding the potassium, however, the problems can more serious when residue containing the oxide of this element is recycled. Sodium, which in normal conditions is not a problem in the blast furnace, may cause similar problems when its oxide is introduced in the furnace through the use of residues in the charge.