Optimisation of permeability bars to customise sinter plants on changing demands (OPTIPER)

Abstract

Most iron ore sinter plants use permeability bars to raise productivity. This project investigated their influences on the process by laboratory and operational trials and special measurements of local profiles. A new transient 2D model basing on Comsol Multiphysics was developed which is able to describe the differences across bed height and width. General knowledge and recommendations were derived. The permeability bars were proven to raise the cold permeability to some extent but even more effective is the folding of the burn-through profile across the strand width. The bars raise the cold permeability just locally with a width of a few centimeters beyond the bars in similar fashion even for very different sinter mixes. The influences of horizontal and vertical bars interact and may cause detrimental effects if not properly tuned. Vertical bars had the best effect when mounted inclined, raising in direction of the strand movement. With optimum bar configuration the sinter speed can be raised by up to 40%. High sinter speed demands higher coke rate to retain the time-temperature profiles during sintering. Since even properly designed bars increase the local inhomogeneities, the average sinter strength usually decreases slightly. Optimum results were obtained either with two stacked rows of horizontal bars with approximately 20cm spacing or with a combination of vertical bars with 30-40cm spacing and horizontal bars in-between. The bar design can be optimized basing on a statistic analysis of the thermal profiles at discharge supported by calculations with the new 2D model.