Comments on 'fish hook effect in classifier efficiency curves' in recent publications in Powder Technology

This note deals with reports of fish hook effect in classifier efficiency curves in recent publications in Powder Technology. Particle size characterisation methods followed in all of them are critically examined. It is shown that where the particle size distributions are determined by laser diffractometry, there is a distinct possibility that correct optical parameters of the test materials may not have been used. In one occurrence, where sieving is the method for measurement of particle size, sufficient details are not available. In another study, the method of size analysis is not disclosed. That is, in all the cases, the accuracy in estimating the efficiency and hence the quality of the data cannot be assessed. Consequentially, the results of all these reports on fish hook should be treated with caution. (C) 2015 Elsevier B.V. All rights reserved.