Burden distribution control and its optimisation under high pellet operation

Abstract

Gas distribution control under high pellet blast furnace (BF) burden operation is more difficult than with sinter due to low angle of repose, high rolling characteristics and layer collapse tendency. Also heavier pellets exert a pushing effect on the preceding coke layer thereby forcing coke towards wall with the pellets also rolling down towards the centre. High pellet proportion at the centre promotes high peripheral flow affecting the burden layer profile and process stability. In order to achieve accurate gas distribution, changes in batch sequence discharge at the stock house and material discharge rate inside the furnace were altered. To avoid excessive rolling of pellets inside the furnace, ore and coke falling trajectory was monitored and optimised to enhance central gas flow without centre coke charging. With a high pellet content of up to 70–80%, BF-1 productivity up to 2·1 t m⁻³ per day and fuel rate down to 570 kg/tonne of hot metal was achieved.