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FLOWABILITY OF SMELTING GRADE ALUMINA

Roach, G.I.D. and Reid, G.

Poor flowability of smelting grade alumina can result in handling problems in both the ore transportation systems and in the pot room; consequently the flowability of the alumina is an important quality parameter. The flow funnel test, as proposed by Hsieh (Light Metals, 1987), has been used as a measure of flowability for various laboratory-produced and smelting grade aluminas. The repeatability of the test to a number of parameters including moisture content, electrostatics and the packing of the sample in the funnel was investigated. The measured test parameter, the flow time, is sensitive to the moisture content for some aluminas. The flowability, when reported on a mass basis, is sensitive to the bulk density of the alumina; this is a consequence of the flow funnel test being, in essence, a volume measure. The flow times, as determined through the 2.4mm orifices of the flow funnel, correlated directly with the flow times measured with a 23mm orifice. Particle size had the most significant effect on flowability; the fines content had the largest effect, the more fines the longer the flow time. Particle shape appears to have a small but significant effect on flow time. One factor causing major variations in flow times for specific aluminas has still to be identified.