Melting - pre-study of models and mapping : physical modeling of scrap melting

A lot can be won by better use of the steel. For example the higher strength the less material is needed and less material gives easier transportation, less discharge and energy and need less resource. Scrap has been used in steel industry for over a century. This master thesis is a part of a European commission project called “Control and optimisation of scrap charging strategies and melting operations to increase steel recycling ratio”. Mefos is a partner of that project and this master thesis contains the parts “Pre-study of models and mapping” and “Physical modelling of scrap melting”. Melting of scrap metal is of increasing interest to the metallurgical industry since it allows the recycling of metals at a fraction of the original production cost. This is in some way a new area, which is seen by the results in the study. But in some areas this has been looked on, for example in Japan and Canada there has been some interesting work on this field. Some theories of melting are commented, and examples are given on the enthalpy-porosity method, the conservation element/solution element method and the homogenization theory. This master thesis is presenting melting of scrap steel in an EAF, electric arc furnace. The melting process is depending on the heat transfer from the arc and the convective heat transfer in the liquid metal. Scrap metal refers to either metal chopped from the end of ingots or compressed blocks of used beverage containers. This means that the scrap is of various shapes. The heat and mass transfer between liquid and solid phases results in a complex problem. As soon as the melting begins the molten liquid drips down toward the bottom of the furnace. Thereafter, the molten liquid level rises while the height of the scrap metal decreases. The scrap is heated both from the arc and the molten liquid at the bottom. In the physical model the electric arc is simulated by a hot-air gun, melting ice instead of iron scrap. The experiments in the physical model are to be used as input in a CFD-analysis. CFD stands for Computational Fluid Dynamics, and is a form of computer simulation.Validerat; 20101217 (root