Experimental investigation of the shrinkage and cracking behaviour of fine participate filter cakes

Regarding the dewatering of fine particulate products by means of gas differential pressure, the formation of shrinkage cracks in undersaturated filter cakes is a frequent restriction. The crack formation can significantly interfere with the filtration process, and in adverse cases even make the process impossible. As up to now there has been only a limited physical background, the currently known countermeasures which beneficially influence the formation of cracks are insufficient. For this reason, the aim of the experimental studies presented was to get basic information about the shrinkage behaviour, the possibilities of influencing it, and the correlation between skrinkage and cracking behaviour. The experiments were made on bench scale with different organic and inorganic products. In this paper, the influence of the compressive pressure as well as the surface tension on the extent and the course of the shrinkage process are discussed. Furthermore, the experimental set-up, the experimental procedure and the evaluation methods are described.