SOFTENING AND MELTING MODELING OF IRON ORE PARTICLES USING A CFD-DEM COUPLING METHOD

The iron-bearing particles start softening and melting because of the weight of burden
above and the high temperature in the middle of the blast furnace so-called cohesive zone. In
this region, as particles are softened, the void space between particles decreases. As the
temperature increases further, the softened particles start melting and generate two different
liquids: molten iron and slag. Then the generated liquids trickle down to the lower part of the
blast furnace. The softening and melting process forms the impermeable ferrous layers forcing
gas to flow horizontally through the permeable coke windows. These phenomena have a big
effect on the operation of the blast furnace, and since it is not possible to interrupt the blast
furnace to investigate details of the phenomena occurring inside, the numerical simulation
becomes more practical. In this contribution, the eXtended Discrete Element Method
(XDEM) as an advanced numerical tool based on the discrete-continuous framework, is used.
Within this model, the gas and liquid phases are described by computational fluid dynamics
(CFD) and the soft-sphere discrete element approach (DEM) is used for the coke and iron ore
particles. Continuous phases are coupled to the discrete entities through mass, momentum,
and energy exchange. Moreover, the internal temperature distribution of the particles is
described. The particle’s deformation, temperature, melting, and shrinking along with the
saturation of molten iron and slag are examined using the XDEM method.