EUROPEAN STEEL TECHNOLOGY AND APPLICATION DAYS 2017 - ESTAD 2017

Electromagnetic, mechanical or gas stirring can improve thermal, mechanical and chemical mixing. Bottom gas stirring is the dominant method. Physical modeling has been extensively employed in the past 40 years to describe mixing phenomena due to bottom gas stirring in metallurgical ladles. The opacity of the steel/slag system and its scale are two factors that impose limitations to fully describe mixing phenomena employing industrial size ladles. By using a water model the bubble plume, bubble size and recirculation loops are easily observed. Mixing efficiency is measured in terms of mixing time, however, mixing time is a parameter that depends on many process variables: gas flow rate; number, radial position and separation angle of porous plugs; slag thickness, ladle aspect ratio, diameter of porous plug, tracer concentration, position of tracer measurement probe, etc. In the first 30 years, the top slag layer was neglected. It is well known today that the top slag layer promotes drastic changes on mixing phenomena. Our current understanding from physical modeling is still far from complete not only because an accurate representation of the real steel/slag system is still missing but also due to the challenges to keep constant relevant process parameters during the experimental work. This situation explains the broad optimum conditions reported by many re-searchers in the past.