Abstract: A centrifugal jig of the type in which a feed slurry is introduced into a rotating chamber bounded radially by a screen provided with ragging on its inner surface. The ragging is repetitively dilated in a circumferential sequence while the container rotates.

Abstract: A centrifugal jig of the type in which a feed slurry is introduced into a container rotating about a vertical axis in a region radially bounded by a screen. The screen is preferably substantially parabolic in shape. Ragging is provided on the screen's inner surface and water is provided in the hutch region on the opposite side of the screen. The water in the hutch region is pulsed repetitiously to dilate the ragging and pulsion of the hutch water is achieved at an interface such as a diaphragm interface or an air/water interface. The interface is positioned substantially wholly beyond the projected free surface of the feed material.

Abstract: A valve for the proportioning of fluid flow between orifices (14,15) consists of a first cylinder (16) provided with a tapering circumferential groove (19) in its periphery, and a pair of cylinders (17,18) contacting the first cylinder respectively in the path between those orifices and a single orifice (13). The pair of cylinders (17,18) have tapered circumferential grooves (20,21) arranged so that rotation of the cylinders causes opening of one path and closing of the other.

Abstract: A fluid control valve of the kind in which a pair of cylindrical rollers (26,27) are provided with complementary peripheral grooves (32) the cross-section of which is tapered so as to form an aperture the size of which is varied by rotation of the rollers. For sealing the rollers within a chamber formed by a valve liner (34,35) the cylinder peripheries are provided with oppositely inclined sealing teeth (43,44) and resilient sealing projections (43) which engage in the closed position of the valve. Complementary ramped formations (46,47) are provided on the lining and ends of the rollers.

Abstract: A fluid control valve has two cylinders arranged parallel to each other with their surfaces in contact. The cylinders are rotated in opposite directions such that their contact surfaces move in the same direction. At least one of the cylinders has a groove formed in its surface extending partially around the circumference and varying in depth along its extent to define an aperture for fluid to flow through. This aperture can be varied in size by rotating the cylinders thereby controlling the flow rate of fluid through the valve. The cylinders are formed with gear teeth on their surfaces which intermesh with each other to provide a seal between the cylinders. The cylinders are rotated by engaged pinion gears driven by suitable drive means.

Abstract: Fine particles such as minerals in a slurry are separated according to their specific gravity by cyclic centrifugal acceleration preduced by rotating a chamber (40) about its own axis and a further axis. Particles of greatest specific gravity are removed from the chamber (40) in the region of its side wall most remote from the further axis.