Furnace Operations to Reduce Dross Generation
While it is generally acknowledged that dross generation should be kept to a minimum, too often, the importance of maximising the aluminium content of the dross is overlooked. Some mistakenly believe that a low metal content is a good thing and that the aluminium is being kept in the furnace. In reality, this metal is most likely being lost due to insufficient cooling and thermiting. Much can be gleaned from looking at the dross that is generated in a casthouse; in fact, the quality of dross can provide a good indication of the overall efficiency of the operation. Even with the very low aluminium prices of today, of circa. US$1400 per tonne, a reduction in dross generation within the furnace can provide huge savings per year. Effective dross management also results in better metal quality, improved fuel efficiency, prolonged refractory life and improved yield in the entire facility. This paper will look at how dross is generated within the furnace in the first place, followed by ways to minimize the dross generation within the furnace using continuous and sub-surface circulation which can also provide significant energy and CO2 reductions. A separate paper will discuss dross processing options and possibilities. In summary, by careful attention to the equipment and process techniques around the furnace and the follow-on dross management significant cost savings and environmental benefits can be realized by cast house operations.
J. A. Taylor, J. F. Grandfield, A. Prasad
A. Peel et al., "Furnace Operations to Reduce Dross Generation", Materials Science Forum, Vol. 630, pp. 45-52, 2010