PROPERTIES OF STEELMAKING DUSTS FROM DRY DUST SEPARATORS

During the production of plain carbon steel from hot metal and/or scrap considerable amounts of dust-laden off-gases are produced. In de-dusting of these off-gases considerable amounts of fine grained residues are produced, which have to be stored, transported and handled. Thereby, the flow-related properties of the dusts are of great importance. In this study the mechanical properties of dusts from dry off-gas de-dusting in steelmaking plants were investigated. The mass median diameters of electric arc furnace (EAF) dust, basic oxygen furnace (BOF) primary de-dusting dust and vacuum degassing dust (VD) were in the range of a few micrometer, while it was up to more than 100 mu m for the residues from the pre-separators in EAF and BOF dedusting. The values for the particle density were quite similar for all dusts (approximately 3,800-4,800 kg/m(3)), but the bulk density of the dusts varied in a wide range (approximately 190-1,900 kg/m(3)). With respect to the flow relevant parameters - flowability, angle of internal friction, wall friction angle and angle of repose - the investigated dusts can be split into two groups: the coarse residues from the pre-separators, which are characterized by low values for the angles and a good flowability, and all other dusts with higher values for the angles and a flowability in the range of very cohesive to cohesive.