Abstract: A draft tube mixer is disclosed particularly adapted for use with digestion processes and apparatus wherein a vertical shaft (13) is driven by motor (15) through a suitable drive (14) to rotate a ragless propeller (12). The propeller (12) has a series of three lobes or blades (40-42) which are concentrically arranged at 120.degree. apart positions so that the minimum diameter of the blades are at the ends of a hub (43) from which the blades integrally extend. The blades extend over the length of the hub over about a 360.degree. of rotary motion helix. The blades (40-42) are symmetrical from their ends to the mid points on the vanes from either direction top or bottom so that the propeller is reversible without loss of efficiency.

Abstract: A lime slaking system for hydration of lime and removal of unwanted grit, particularly for formation of reactive slaked lime to be used in SO.sub.2 scrubbing of effluent gases, comprising a series of slaking vessels (10, 12) for reacting CaO and water while agitating the reactants, a dilution mix tank (14) receiving a viscous slaked lime slurry from the vessels, diluent for the dilution tank comprising an upstream classifier overflow stream (16), a cyclone (19) receiving pumped diluted slurry from tank (14), the overflow (21) of the cyclone providing usable slaked lime product and the underflow (22) exiting to the upstream classifier (24) where grit materials are separated and removed. Dilution for effective classification is provided by spent scrubbing process water containing appreciable sulfate ions.

Abstract: A draft tube mixer is disclosed particularly adapted for use with digestion processes and apparatus wherein a vertical shaft (13) is driven by motor (15) through a suitable drive (14) to rotate a ragless propeller (12). The propeller (12) has a series of three lobes or blades (40-42) which are concentrically arranged at 120.degree. apart positions so that the minimum diameter of the blades are at the ends of a hub (43) from which the blades integrally extend. The blades extend over the length of the hub over about a 360.degree. of rotary motion. The blades (40-42) are symmetrical from their ends to the mid points on the vanes from either direction top or bottom so that the propeller is reversible without loss of efficiency.

Abstract: Methods and apparatus are disclosed for the rapid and efficient drilling of oil well and other types of bore holes through tough abrasive underground formations, which methods and apparatus utilize high drag intermittent contact and cooling techniques to provide good rates of penetration with low wear and heat deterioration on the drilling tools.

Abstract: A rotary drill bit comprising a bit body having at least one depending leg at its lower end and at least one roller cutter rotatably mounted on the leg. The roller cutter comprises a frustoconical roller cutter body and a plurality of cutting elements projecting from the cutter body to tips adapted to bear on the bottom of the well bore, with the tips defining, upon rotation of the bit, a first cutting surface of the bit extending over substantially the entire area of the bottom of the well bore. At least one drag cutter extends down from the bit body and comprises a support and a plurality of drag cutting elements on the support, each having a lower cutting edge.

Abstract: An oil well drilling bit is disclosed of the type utilizing hard metal inserts in the rolling cutters wherein each row of inserts on each cutter is located thereon in a sinusoidal or varying pattern rather than the strictly circumferential pattern of the prior art.