In the context of high coal injection and high productivity operation, the coke behaviour inside the blast furnace hearth is the main parameter to control. Different and complementary investigations as radioactive and helium tracer injections, liquids and coke samplings, have been carried out at Sollac Fos BF I using the tuyere probe to determine the hearth permeability and its evolutions as a function of the main control parameters, and to understand the hearth activity. The results of all these experiments give a very consistent picture of a heterogeneous hearth with three concentric areas of various permeabilities to gas and liquids. A two concentric zones model has been built, which is in good agreement with the experimental results. It enables to evaluate the impact of the central zone on the liquids flow at the periphery.
