The use of the ring gap sizer for characterization of particle shape in the sieve range

The ring gap sizer sorts particles by their minimum dimension, i.e. thickness. This new instrument has been used to establish particle shape factors and distributions of powders in the sieve range.The powders investigated were quartz and tablet granules, i.e. powders consisting of non-equidimensional particles. It is shown that the combination of results obtained by the ring gap sizer, dry sieving and microscopy gave log-normal distributions of particle flakiness. This was in good agreement with results obtained by a microscopical reference method.For the quartz powder the variation of particle elongation with changing particle size was also determined, using the ring gap sizer to obtain samples of varying particle size, which were then measured on length and breadth by microscopy.Additionally, the two average values of flakiness and elongation have been used to calculate the Heywood surface and volume shape coefficients.