Study on flow characteristics of primary blast furnace slag

Abstract

The primary slag generated in the cohesive zone of the blast furnace determines the fuel rate as well as the quality of the hot metal in terms of its silicon content. This is because in the cohesive zone the softened slag chokes the path of gas flow, interfering with the permeability of the bed. Therefore, the cohesive zone which starts with the softening of the primary slag and ends with its flow should be formed lower down the furnace and should be a narrow one with a minimum difference between the flow temperature and the softening temperature. In the present work pellets with C/S ratio ranging from 1.8 to 2.4 with a fixed MgO content of 10% are reduced in the laboratory at different temperature ranging from 1200 C – 1400 C. Synthetic slags prepared in the laboratory in line with the comparison of reduced pellets are analyzed for its flow characteristics using the heating microscope (German Standard 51730). It is observed that under the composition examined, the pellet with C/S ratio 2.0 rendered the best result with the highest softening temperature and lowest flow temperature.