Abstract: The conveyor of a decanter centrifuge includes a small outside diameter central hub extending for at least a portion of the longitudinal length. On the hub is attached a series of longitudinally- and radially-extending shaped ribs, which in turn attach to larger ribs that transverse an open feed zone. The longitudinal and transversing ribs support a ribbon conveyor flight. The open feed zone serves to decrease feed solids degradation. The ribs outside the feed zone serve to improve interface stability and minimize washout. The overall structure of the conveyor is mechanically stiffer and less prone to vibration. The conveyor is lighter and less expensive to construct.

Abstract: A decanter centrifuge is equipped with a conventional screw conveyor which advances separated solids or heavy phase material toward a solids discharge zone, and it is also equipped with discharge nozzles mounted on the bowl wall for discharging concentrated solids therethrough from the solids discharge zone. In addition to light phase or liquid discharge means, the centrifuge is further provided with a recycle system which returns at least a portion of the discharged solids to the solids discharge zone via a conduit. At the end of the conduit are recycle tubes mounted on the hub of the screw conveyor. The effect of feeding recycled solids to the discharge zone, to which newly separated solids is also being advanced, is to increase the solids concentration of the solids being discharged by the discharge nozzles.

Abstract: Screw conveyor of solid bowl centrifuge has its flight member modified at the bowl dry beach area by welding sheet metal, for example, to trailing surfaces of the flight forming a chamber for rinse liquid driven thereinto. Leading or working surfaces of the flight are provided with a plurality of series of orifices per 360.degree. revolution thereof, each series comprising spaced orifices extending inwardly from a distal portion thereof and preferentially angled therethrough. Overflow passageways with cooperating baffles are provided. Thus, rinse liquid passes onto solids pile surfaces through orifices immediately inwardly thereof as well as through orifices submerged by the solids for passage of rinse liquid thereinto.

Abstract: A centrifuge conveyor is provided with improved hard surfacing wherein assemblies of backing members and wear-resistant members are welded by the backing member to the conveyor. An assembly may be made unitary by providing a hole in either or both of the wear-resistant member and the backing member and securing them with means extending through the hole or holes. In the event that repair is necessary, an individual assembly may be replaced by welding technique, or the backing tile may be left in place and only the wear-resistant member replaced by removing and replacing the securing means. Each fragile wear-resistant member is braced against deflection at its outer portion through its backing member to the conveyor. The embodiments employ a plurality of wear-resistant members, each such member being accurately pressed from sintered tungsten carbide.

Abstract: A 3-phase centrifugal decanter separates a mixture of a light liquid phase, a heavy liquid phase, and solids. The decanter employs two types of dam holders, each carrying a substantially similar dam capable of passing either liquid phase therethrough depending upon the type holder carrying the dam. By mounting the holders with their dams to prepositioned openings provided in a front-located hub, both liquid phases are caused to be discharged through the hub to specified compartments. The two types of holders are capable of being mounted interchangeably to the hub openings. Dams are interchangeable in the holders. By interchanging the positions of the holders, each liquid phase may now be directed to the other's compartment. The holder carrying the dam for discharging heavy liquid phase cooperates with an underdam which prevents light liquid phase from passing through or therearound.

Abstract: A centrifuge conveyor is provided with improved hard surfacing wherein unitary subassemblies of backing tiles and wear-resistant members are welded by the backing tile to the conveyor. A subassembly is made unitary by the interengagement of the wear-resistant member to an undercut groove in the backing tile and by bonding with a heat reactive adhesive or grout applied to the interengaging parts. Each fragile wear-resistant member is braced against deflection at its outer portion through its backing tile to the conveyor. The preferred embodiment employs a plurality of wear-resistant members per backing tile, each such member being accurately pressed to its intricate, interlocking shape from sintered tungsten carbide.

Abstract: A new crystalline form of quinacridone is prepared by conditioning crude quinacridone with a water-insoluble liquid having at least one hydroxyl group, a surfactant, and water.