7TH EUROPEAN COKE AND IRONMAKING CONGRESS - ECIC 2016

Pulverised coal injection (PCI) has been commonly established into the blast furnace (BF) operation practice. However due to volatile coal market, blast furnace operators are often forced to change coals used for injection. Handling new coals presents a great challenge. An estimation of their compatibility in the blast furnace process based on chemical analysis alone is often not sufficient. The coal composition may change from mining area and origin. The chemical compounds (proximate and ultimate analyses) are an important indicator for selecting coals suitable for BF injection. However, these are not the only criteria, which have a significant impact on coals conversion behaviour. Factors such as particle size and size distribution, calorific value, ash fusion temperature, ash composition, maceral composition, porosity/specific surface, pore characteristics, grindability etc. also play an important role. At the Dept. of Ferrous Metallurgy (IEHK) at RWTH Aachen University a method to rank the efficiency of coal conversion in the BF raceway has been developed. It is based on the weighting of the effects of chemical, physical and mechanical properties on PC conversion and not fitted for specific BF operation conditions. Calculations are based on coal characteristics and injection mainly conducted at the IEHK. The results have been collected in a database and were evaluated. Different coal properties, which influence the conversion behaviour, were identified and ranked. The model approach estimates the conversion behaviour of coals under the raceway conditions. This aspect is an important part in evaluating the suitability/compatibility of coals for BF injection.