Process improvements in iron and steel industry by analysis of heat and mass transfer

The purpose of this paper is, firstly, a critical review of the recent lite rature about heat and fluid flow and mixing phenomena for some main process es in the iron and steel industry with the aim of their improvement and, th us, cost reduction. The criteria for bubbling and jetting during gas inject ion are examined, including interaction of the powder load on flow regimes. It is important to know the domains of bubbling and jetting behavior in or der to minimize the effect of back attack, which is responsible for additio nal wear of bottom lines and tuyere pipes. It is shown that two types of mo dels can describe the mixing process: the turbulent recirculation model and the model of partial volumes. The comparison between calculated time depen dencies and plant results confirmed the practicability and usefulness of th e model of partial volumes. It was also shown that the water model results for ladles might be transferred to plant conditions. Subsequently, some remarks are made about "generalized thermodynamics" and synergetics and their applications to mass transfer in the steel industry. As an example, the existence of considerable oxidation gradients and diffus ion streams of oxygen can cause pumping of impurities in the absence of con vection, i.e. under conditions of pure diffusion. The above concepts have been applied in various cases of the iron and steel industry, in particular for optimization of ingot solidification at contin uous casting. (C) 2001 Published by Elsevier Science Ltd.