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

One of the factors that could limit the maximum rate of pulverised coal inj ection (PCI) in a blast furnace is the accumulation of unburnt char, due to incomplete combustion. Consumption of this unburnt char in the blast furna ce could result in achieving increased PCI rates. The Co-operative Research Centre (CRC) for Black Coal Utilisation in Australia, is engaged in severa l projects to develop an understanding of the possible modes of consumption of the unburnt char within a blast furnace, through investigation of the i nteraction of different carbonaceous materials with slag, metal and gas pha ses. This paper presents some of the results of the investigation of slag/c arbon interactions, studied in terms of the wettability at the slag/carbon interface. Influence of temperature on the wettability at slag/carbon inter face has been investigated by measuring the variation of dynamic contact an gle with time, at 3 different temperatures, 1500 degreesC, 1600 degreesC an d 1700 degreesC for a blast furnace slag composition interacting with vario us carbonaceous materials, including graphite and chars. An increase in tem perature generally results in improved wettability at the slag/carbon inter face. The wetting behaviour of the slag on different carbonaceous materials can be explained on the basis of the changes in the interfacial energy dur ing the interaction. An increase in temperature is associated with a greate r 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 pa per discusses the wettability of various carbonaceous materials by the slag at different temperatures and the associated phenomena.