Control of charge distribution to optimise metal quality in the production of ferro alloys

The quality of metal is a critical factor in deciding the value of the metal. This is a major incentive to control the level of impurities in the ferro alloys. The impurities come from the gangue in the ore, the tlux added and the reductant used. The impurity levels are usually controlled by choice of the type of raw material or the quantity of raw material used. This disturbs the operation of the furnace considerably. However, it is also possible to control the level of impurities by careful control of the burden distribution in the furnace. The thermo-chemistry of the production of ferro-chrome was analysed to demonstrate the phenomenon. Plant trials established this as a viable means of controlling the quality of the ferro alloy produced. It also demonstrated that this process reduced the specific power consumption in the production of ferro-chromium. as predicted by the model. A similar approach may be applied to control the level of aluminium in ferro-alloys such as ferro silicon.