Particle Size Analysis (Special Publications),Used

Excerpt. Reprinted by permission. All rights reserved.Particle Size AnalysisBy N.G. StanleyWood, R.W. Lines The Royal Society of ChemistryCopyright 1992 The Royal Society of ChemistryAll rights reserved.ISBN: 9780851864877CHAPTER 125 Years of Particle Size ConferencesB. ScarlettDEPARTMENT OF CHEMICAL ENGINEERING, TECHNICAL UNIVERSITY, P.O. BOX 5045, DELFT, 2600 GA, THE NETHERLANDS1 1966 AND ALL THATIt is almost precisely twenty five years since the first of these conferences, organised then by the Particle Size SubCommittee of the Society of Analytical Chemistry which has now grown into the Particle Size Characterisation Group of the Analytical Division of the Royal Society of Chemistry. The subcommittee had recently completed a review of 74 different methods of particle size analysis and these efforts were the inspiration both for the first conference and for the formation of the permanent subject group. This is the seventh conference in the series and it is entirely appropriate that it should be held in the same place, at Loughborough University. The proceedings of each of the conferences is permanently documented by a bound book of conference proceedings. Several authors feature in all the seven conferences.The closing address at the first conference was given by Professor Harold Heywood, an address which was based on many years of experience and which could be given, almost without modification, at the end of this conference and still be entirely appropriate. Thus, some truths do not change and although they must be learnt anew by each succeeding generation, they remain essentially the same.The developments which he foresaw have largely occurred over the intervening twenty five years but it may be that now those basic messages have even more practical importance and that the rate of development grows exponentially. In this paper, my intention is to restate some of the message of Heywood and to illustrate it in the circumstances of today.2 WHY OH WHY?The first quotation I would like to take concerns why particle size measurement is important, why it commands the attention of professional groups, companies, journals and conferences specifically devoted to its development. Heywood wrote:'However, it must be realised that particle size analysis is not an objective in itself but is a means to an end, the end being the correlation of powder properties with some process of manufacture, usage or preparation.'A particle size measurement does not have a meaning unless the objective of the measurement is also specified. Thus, the techniques which should be used depend entirely on the accuracy which is required and the circumstances of place and time in which the measurements must be made. There is no such thing as the 'best' particle size technique unless the circumstances are also specified. A particle analysis laboratory cannot operate on the same basis as some normal analytical laboratories, samples come in and numbers go out. In a particle analysis, the question must always first be addressed. 'What do we need to know?' Another way of saying this is that, eventually, particle analysis is an engineering tool, not a basic science. Engineers must use all the known laws of science to solve the particular problem with which they are confronted in the most elegant manner.In this respect, it may be that the circumstances are more difficult than they were twenty five years ago. At that time, the number of instruments was more restricted than now as was certainly the number of companies who supplied those instruments. Current instrument manufacturers must try to provide a package of hardware and software which will handle a large number of powders and applications. The commercially available instruments are thus, inevitably, a compromise between what is desirable and what is possible, the same instrument being sometimes too sophisticated and sometimes inadequate. To be a manufacturer of particle measuring