Most of plants producing or treating solid-liquid mixtures generate a large amount of residual sludge. Many mineral types of slurry occur in a large range of industrial wastes, including those from mining, ceramics, paper and health care industries. Nowadays, according to new environmental regulations, a reduction of these waste volumes is required. Owing to their relatively low energy cost, filtration processes are often preferred to thermal drying devices to achieve this volume reduction. Because of the difficulty of the theology behaviour of the residual sludge and its stability, we chose to use a synthetic suspension approach to the residual sludge. In this work, mineral sludge (kaolin) was considered. Some experiments were carried out on laboratory filtration-compress ion cells; the use of the Ruth relationship and the approach of Shirato and co-workers were tested to characterise this slurry in filtration and compression, respectively.