PYROMETALLURGICAL SIGNIFICANCE OF MARANGONI FLOW - MECHANISM AND CONTRIBUTIONS TO PROCESSING

In many pyrometallurgical refining processes, Marangoni convection pla ys an important role because it enhances the mass transport through th e boundary layers. Marangoni flow is created by a surface-tension grad ient by means of a compositional gradient or temperature gradient or a n electrical potential gradient. A great deal of experimental difficul ties exist at high temperatures to observe and to identify Marangoni f low from other competitive phenomena. However, this review discusses t he mechanism and contribution of Marangoni flow to the following pyrom etallurgical processes; the effect of changing the nitrogen compositio n on the surface of liquid iron, current efficiency in aluminium elect rolysis, inclusion distribution in gas-metal are welding, and the sepa ration of metal or matte droplets from slag. It is concluded that an u nderstanding of the role of Marangoni flow on the kinetics of these op erations is important.