Some mineral processing plants encounter difficulties in dewatering pulps using clarifier/thickener (C/T) equipment due to a layer of fine particles, air bubbles and chemicals formed at the top of the liquid in the thickener. Such layers are very stable and form a cap on the C/T. The dewatering performance of the C/T then deteriorates under these conditions, and a high percentage of solids is contained in the thickener overflow. A process for removing water from rock slurry containing a wide range of particle sizes in mineral processing operations has been developed. The process includes: (a) classifying the feed slurry into two size fractions, namely a coarse fraction and a fine fraction, (b) treating the fine fraction (and the coarse fraction if required) with a selected flocculant, and (3) thickening the flocculated slurry in sedimentation equipment to separate liquid from solids.