Laboratory testing was conducted to evaluate the performance of a pilot-scale, T.H. filter press for dewatering fine silica-sand slurries. The plate-and-frame filter press is fully automated and is equipped with a hydraulic system, which operates the plate and diaphragm feed pumps up to a pressure of 1035 kPa. The unit contains a single set of plates with an effective filtration area of 0.16 m 2 on each plate. A thickener underflow sample was collected from a silica-sand processing plant located in northeastern United States. The sample was nominal -0.15 mm and contained 76% of -0.075 mm material, with 37% of the material finer than 0.025 mm. A statistical design was developed to evaluate the effects of filter time, air-drying time, and air pressure on filter cake moisture, filtrate flow rate and solids content, solids recovery, and filter press unit capacity. Product moistures ranged from 12.0% to 17.5% with filtrate solids contents less than 0.1% by weight. Product unit capacities ranged from 58 kg/hr/m 2 to 128 kg/hr/m 2 with solids recoveries over 99.5% in all cases. Lower cake moistures were usually associated with lower unit capacities. The results indicate that the filter press is capable of producing handleable filter cake without the use of additional flocculants.