[en] Solid-liquid separation is one of the most important sections in mineral processing. High percentage of clay material and fine particles (-200 mesh) cause different problems in separation of uranium leach liquor from the residual solid particles in filtration unit of Bandar Abbas Uranium Plant. The laboratory tests showed that thickener is a suitable device for solid-liquid separation, after leaching unit. For this reason, thickeners were selected for separating of leach liquor from the residual solid particles. For determination of the size and number of thickeners, sedimentation experiments were performed with different Flocculent, ^Magna floc LT-25^was selected as a suitable Flocculent in 75 g/ton. The diameter of thickener was determined to be 13-14 m. In the counter current decantation, the loss percentage of uranium, using 5 thickeners, was selected to be 2.09%