Investigation of accretion formation in a blast furnace shaft

The investigations of the project were carried out at four different blast furnaces. During the project, three of them were equipped with additional measurements. Installation activities included thermocouples, heat-flux meters, staves with instrumentation for heat-flux measurement and a small horizontal lance. The additional measurement data was necessary for the development of accretion estimation models and for the investigation of the accretion formation process. The distribution of accretions in the shaft was documented. Samples were taken out of accretions during blast furnace stoppages. Their acquisition was simplified with newly developed sampling devices. The samples were analysed to determine chemical and mineralogical properties and the thermal conductivity. Samples were mainly made up of reduced iron or of coke and sinter structures glued together by zinc- or alkali-compounds. Together with a newly developed offline model for the simulation of accretion formation, different parameters influencing the formation process were identified. The main parameters are: Burden material composition, blast furnace operating conditions and the cooling-system. Countermeasures to prevent excessive accretion growth were stated. Different models to identify accretion formation were developed and an overview is presented. Different models were necessary to distinguish between the various measurement, cooling-system and blast furnace set-ups. Most of the models are already implemented and in operational use. For some of them application at other blast furnaces was already realised or is possible.