Influence of particle properties on the size of agglomerated metallurgical powders

The disintegration of agglomerates of solid charge used in a nickel flash furnace has been investigated to improve the understanding and modelling of furnace operation. A laboratory-scale experimental rig was constructed to non-intrusively measure the agglomerate size distribution of solid charge suspended in air, and to observe the powder injection process. Measurements indicated sizes from 200 to 7000 gm of agglomerated solid charge were present under turbulent conditions similar to that experienced in a flash furnace. The current work indicates that the primary particle size distribution of feed significantly affected the size of suspended agglomerates that were formed, while the amount of fine (-38 mu m) material strongly influenced the strength of agglomerates. Specifically, increasing the concentration of -38 gm particles in nickel concentrate from 42 vol.% to 66 vol.% increased the volume of agglomerated material by a factor of more than 7. The effect of particle packing was shown to influence the agglomerate size distribution of feed, although this effect was inconsistent and required more study. Experiments investigating the effect of particle shape on agglomerate size showed only a slight effect that may not be significant. It is expected that reducing the amount of fine material in flash furnace feed would cause a decrease in agglomerate sizes within the reaction shaft, and lead to faster reaction times. It is recommended that the agglomerability of furnace feed be taken into account in computational models of flash furnace reactions in future work. (C) 2008 Elsevier B.V. All rights reserved.