Redesign of a Tata Steel transfer chute with dust liberation problems

Abstract

Dust liberation in transfer chutes has been a persistent problem in the bulk handling industry, with an increasing demand for solutions due to the tightening of environmental regulations. An investigation into the root causes of dust liberation and a chute redesign with improvements in dust liberation potential has been performed in this research. The biggest challenges of this redesign being that the case study chute is a multimaterial, movable chute with differing flow rates and a redirection of material by 90±. The main, root causes of dust liberation have been found to be material impact, air entrainment and compact containment of the granular flow. Measurements at the current transfer chute have been performed to investigate and quantify the problems of the case study chute. Direct measurement of dust in and around transfer chute is often circumvented to measure related issues such as material degradation and air flow measurements, since this makes localizing dust liberation sources and quantification difficult. Therefore, stopped-belt sampling has been performed to find material degradation in a case study chute at Tata Steel, given that impacts cause degradation as well as dust liberation. No conclusive evidence was found due to a lack of samples. Iron ore pellets and sinter were dynamically calibrated using an inclined surface wear tester and simulations in EDEM software were performed for 800 t/h and 1600 t/h flow rates. Three problem areas were found where impacts and bulk density increases provided indications of potential dust liberation. A redesign proposal that uses a hood and spoon concept with movable hood, where the cut-off of the movable chute head needed to be heightened to fit a spoon that can improve flow conditions, was proposed. Improvements in the identified problem areas were found in simulations of the redesign.