Abstract: An assembly for recovering crystals from a slurry comprises a filtration unit including a rotatably mounted cylindrical filter, a slurry input for receiving slurry pressurized by a pump. The filtration unit has an outlet for discharging crystalline material separated from the slurry by the filtration unit. A first hopper connected to the filtration unit at the discharge outlet thereof is provided at a downstream side with a first valve unit which is in turn connected to a second hopper on a downstream side. A second valve unit is coupled to the second hopper at a downstream side thereof. Each of the valve units includes a rotatably mounted dome shaped valve member. The second hopper is provided with a vent extending to a gas storage tank. A conduit links the hoppers to one another for substantially equalizing pressure in the hoppers prior to an opening of the upstream valve during a discharge procedure.