Abstract: A device (10) for sieving and/or mixing is disclosed which includes a base (12) and a container (13) mounted thereon for rotation about an axis which is substantially horizontal. The container has a peripheral wall (14) extending angularly about and longitudinally relative to the axis, and an opening (25) extending longitudinally relative to the axis to provide for movement of material into and out of said space. Means to drive the container angularly about the axis are provided so that any material which is introduced into the container may be processed as required by rotation thereof. The peripheral wall is configured with an internal baffle to prevent material from being delivered when the container is rotated one way, but delivers material from within said space through the opening when the container is moved angularly about its axis in the opposite direction being a predetermined direction of rotation for delivery.