Direct observations of liquid binder–particle interactions: the role of wetting behaviour in agglomerate growth

The use of liquid binders to develop sufficient interaction forces between solid particles to allow for agglomerate growth is a key process in many industries, not least in the production of fertilisers and solid dosage pharmaceuticals. One of the main methods of controlling such processes is to determine the `end-pointʹ of the agglomerate growth from the growth kinetics. However, there is no fundamental theory available that will allow prediction of the end-point from first principles, mainly due to the complex inter-relationship between a host of process variables, including particle size and shape distribution, surface properties, wetting behaviour, agitation energy, etc. This paper details a novel technique, based on micromechanic manipulation, to observe and measure, directly, the interaction behaviour between pairs of particles and liquid binders, which is leading to a better understanding of the mechanisms involved in `wetʹ agglomeration processes and the development of new expressions to predict particle–particle adhesion forces and binder distribution.