Forms of Zinc Occurrence in Blast-Furnace Dust

Resumo

Results are given for a study of the phase and elemental composition of EVRAZ Nizhny Tagil Metallurgical Plant blast-furnace flue dust. An estimate of particle size is performed in a laser analyzer. Dust is represented by a set of particles of calcined charge with sizes from 1.5 to 1170 μm, with a median size of 82.9 μm. The elemental composition of the blast-furnace dust in local sampling points is determined by x-ray microanalysis. The dust consists of large iron oxide particles and fine particles containing MgO, CaO, SiO₂, and Al₂O₃ in the form of complex silicates and ferrites, as well as inclusions of mechanically entrained coke. Zinc is present in form of oxide, sulphide and sulfate compounds as a surface layer on particles with increased thermal conductivity (FeO_x). The zinc and sulfur contents in the layer (1–5 μm) reach 45 and 6%, respectively. The data obtained are useful for substantiating dust treatment processes.