Two prototypes are developed for continuous electrokinetic dewatering of phosphatic clay suspensions. A two-stage design comprised an electrophoretic thickening unit followed by a unit that used electro-osmosis to complete the dewatering. A single-stage design carried out the dewatering in one operation. Rheological measurements showed that the clay suspensions exhibited a yield strength for solids contents greater than 7.5 wt.%. The two-stage prototype had low production rates; whereas, the single-stage design demonstrated efficient production of a dewatered cake with a solids content of 35 wt.% at a dry-clay production rate of 4.5 kg/h m(2) from a feed clay of 10 wt.%. The poor performance of the two-stage design was attributed to an inefficient design for the electrokinetic thickener unit, which was designed to enhance electrophoretic separation; whereas, the desired range of solids content was better suited for electro-osmotic separation. An economic analysis for the single-stage design yielded an estimated total cost of $11-12/metric ton of dry clay produced. The improved operation of the single-stage system was attributed to its optimization for electro-osmotic separation, which was found to be appropriate for the operating range of solids content. (C) 2018 Elsevier Ltd. All rights reserved.