Mineral jig

Mineral jigs or gravity concentrators were designed to allow for separation of materials with different densities. This process is accomplished by flowing a stream of liquid-suspended material over a screen and subjecting the screen to a vertical hydraulic pulsation. This pulsation momentarily expands or dilates the screen bed and allows the heavier materials to work toward the bottom. Heavier material, or concentrate, that is finer than the screen openings will gradually work through the beds and the retention screen into the hutch, or lower compartment. That material, the concentrate, is continuously discharged from this compartment or hutch through a spigot. If the concentrate is coarser than the screen, it will work down to the top of the shot bed, and can be withdrawn either continuously or intermittently. The lighter material, or tailing, will be rejected over the end of the jig.[1]

The mineral jig has been widely used in recovering valuable heavy minerals such as gold, platinum, tin, tungsten and lower density minerals, gemstones such as diamond and sapphire from alluvial or placer deposits. Jigs have also been widely used in hardrock mill applications for recovering of coarse heavy minerals liberated in open or closed grinding circuits. Base metals, iron, manganese ores and barite have also been recovered using jigs. Where the difference between the density of the mineral being sought and the gangue is large, as in the case of gold or platinum, the “Placer Jig” achieves very efficient recoveries even of minus 50 mesh particles.

The mineral jig has certain advantages in placer and hardrock mill flowsheets. In gold recovery the jigs produce highly concentrated products which can be easily upgraded by methods such as barrel amalgamation, treating across shaking tables or processing through centrifugal concentrators. In other placer operations the heavy minerals being sought are recovered efficiently and cheaply with similar high ratios of concentration. In iron, manganese and base metal treatment flowsheets, the jigs are operated to produce marketable grades of concentrate; or, as pre-concentration devices, to reject barren gangue prior to the ore entering the fine grinding section of the mill flowsheet.[2]

The construction of the mineral jig results in maximum utilization of floor area and minimum head room requirements, permitting greater capacity per unit of operating floor area than, for example, shaking tables or other devices. The design of the machine contributes to minimum operating and maintenance costs and negligible parts replacement expense.