PARTICLE SIZE MEASUREMENT OF ALUMINA BY CENTRIFUGING

The application of a centrifuge particle size analyser for the determination of finely ground calcined aluminas was studied. The alumina was dispersed in a water-ace-tone- calgon solution, and centrifuged in a water-calgon solution. Two samples were run simultaneously. A viewer, with 18X magnification, was used to read the sediment height in the centrifuge tube. Reflected light was used to illuminate the centrifuge tube. Thus finely divided aluminas with a narrow size distribution could be measured. Sample size affected the results; the larger the sample size, the coarser the size distribution. The speed of the centrifuge used for the coarsest size fractions also affected the results. If too great a centrifugal force was applied initially, the particle size distribution was too coarse.