Influence of temperature on the wettability at the slag/carbon interface during pulverised coal injection in a blast furnace

Abstract

One of the factors that could limit the maximum rate of pulverised coal injection (PCI) in a blast furnace is the accumulation of unburnt char, due to incomplete combustion. Consumption of this unburnt char in the blast furnace could result in achieving increased PCI rates. The Co-operative Research Centre (CRC) for Black Coal Utilisation in Australia, is engaged in several projects to develop an understanding of the possible modes of consumption of the unburnt char within a blast furnace, through investigation of the interaction of different carbonaceous materials with slag, metal and gas phases. This paper presents some of the results of the investigation of slag/carbon interactions, Studied in terms of the wettability at the slag/carbon interface. Influence of temperature on the wettability at slag/carbon interface has been investigated by measuring the variation of dynamic contact angle with time, at 3 different temperatures, 1500°C, 1600°C and 1700°C for a blast furnace slag composition interacting with various carbonaceous materials, including graphite and chars. An increase in temperature generally results in improved wettability at the slag/carbon interface. The wetting behaviour of the slag on different carbonaceous materials can be explained on the basis of the changes in the interfacial energy during the interaction. An increase in temperature is associated with a greater decrease in interfacial energy due to an increased extent and rate of the reduction reactions and a decrease in surface tension of the slag. This paper discusses the wettability of various carbonaceous materials by the slag at different temperatures and the associated phenomena. © Munksgaard, 2001.