7 CHECK VALVES; SLURRY, SOLIDS-LADEN OR ABRASIVE/CORROSIVE-RESISTANT TYPE CENTRIFUGAL HYDRAULIC PUMP SYSTEMS AND CENTRIFUGAL PUMPS THEREFOR AND PARTS THEREOF CONSISTING OF PUMP CASING, CASING LINERS, IMPELLOR, SHAFT, DRIVE MOTOR, BEARINGS, SEALS, CONNECTING GEARS, SHEAVES, DRIVE BELTS AND FRAME; GRINDING MILL LINERS AND GRINDING MILL GRATES; SCREEN DECKS; AND CHUTE LINERS