Flowability of various dusts collected from the off-gases of a secondary copper smelter
C. Lanzerstorfer - Flowability of various dusts collected from the off-gases of a secondary copper smelter - PARTICUOLOGY, Vol. 25, No. 1, 2016, pp. 68-71
For dust separated from an off-gas reliable flow out of the hoppers of the dust collector and out of the storage silo is important for smooth operation. For this the flow properties of the collected material are crucial. Various dust samples collected from off-gases from a secondary copper smelter were investigated. The mass median diameter of the fine-grained dusts was in the range 0.8 to 1.4 µm, the flowability ranged from “cohesive” to “very cohesive”. For the shaft furnace dust and the anode furnace dust the flowability improved slightly with increasing consolidation stress and their wall friction angles decreased. This is typical behaviour. In contrast, the flowability of the converter dust decreased with increasing consolidation stress and its wall friction angles increased. After pre-shear treatment of the converter dust, its flowability was worse, the wall friction angle was larger and the flowability improved with increasing consolidation stress. This behaviour is explained by the presence of small agglomerates in the dust improving the flowability which were fragmented in the pre-shear treatment. The presence of such agglomerates was confirmed by sieving tests. The visualization of the flowability in a diagram showing the unconfined yield strength dependent upon consolidation stress can be improved by use of logarithmic scaled axes.