ABSTRACT
Jigging is the process of separating the particles of different specific gravity, size and shape by introducing them on a perforated surface (or screen) through which a fluid is made to pulsate alternately. Hydraulic jigs use water as the fluid medium whereas pneumatic jigs use air. The device used for this process is called Jig. Jigs are one of the oldest and most commonly used methods of coal preparation the world over. Recently, the heavy medium separators have become more popular owing to better performance in the case of difficult coals. In coal plants, Jigs are often called Jig boxes, Jig washers, Wash boxes. The extensive use of jigs has been mainly due to low cost of operation, and ability to treat a wide range of size fraction in a single unit. Fines jig can effectively clean from a top size of 13 mm to fines of 100 mesh size. The specific gravity of separation of jigs used in most coal preparation plants varies from 1.30 to 1.90. The optimum capacities range from 200 to 400 tons/hr of feed coal. The basic construction of a Hydraulic jig is shown in Fig. 24.0.1.
