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Residue materials generated in the metallurgical industry have gained an increasing importance, both from the points of view of energy and material supply. A joint process integration model for the integrated steel plant system is developed and used in this paper. It takes into account both residue materials and energy recirculation for the system. The potential for increased recirculation and the effect on the system from an environmental point of view is presented, and implementations and practical experiences are discussed. The model developed can serve as a benchmark for different steelmaking operations and constitute a basis for the continuous work involved in material, energy, environment or economic analyses for the steel production system.

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SSAB Luleå, SSAB Oxelösund, MEFOS and Luleå University of Technology have cooperated in developing theoretical models for prediction of thermal stratification and drainage in steel ladles. Predicted results have been verified by measurements done in production ladles with heat weighs of 105 and 200 tonne as well as in a 7‐tonne pilot plant ladle. The thermal stratification was measured by thermocouples at different depths. The drainage flow was studied by means of tracer experiments. Numerical simulation models of the steel flow were developed for 7, 105 and 200 tonne steel ladles. The agreement between predictions and measurements was found to be good. The conclusion is that CFD simulation gives a good prediction of stratification and drainage flows in production ladles.

The combined movement of steel, slag and gas in a ladle has been studied with the aid of a multiphase CFD model and measurements in production scale. Comparison of model data and measurements in a production ladle has been carried out for three cases: The ‘open eye’ created during gas stirring, the mixing of top slag during gas stirring in the CAS‐OB and finally for studying sculling phenomena. It was found that the simulated ‘open eye’ appears as a central slag‐free zone with a surrounding ‘splash zone’ characterized by the fact that steel is found on top of the slag. The simulated ‘open eye’ corresponds to the ‘splash zone’. The predicted gas stirring in CAS‐OB gives an efficient stirring of the top slag also. This was confirmed by noting that slag samples taken from the ladle seem to be representative of the mean slag composition. Finally, streamlines during stirring have been compared with sculling and wear observed in the production ladle. Good agreement was obtained.