Gravity

Gravity Points : Gravity, Definition, Sink System, Sink Float System, Jig Plunger Gravity System Definition The gravity system relies on the difference in specific gravity between the ore and the gangue for separating the gangue from the mineral. The basic types of gravity concentration systems are the sink system the sink-float system, and the jigging system. (a) Sink System The sink system dumps the mineral that has been ground to the same size and roughly the same shape in to still water. The value, having a higher specific gravity, will sink more rapidly than the gangue. As the gangue floats, a stream of water bears it away, and thus only the ore falls to the bottom. (b) Sink Float System The sink-float system works in the same manner except that water is not used as the floating solution. The floating solution used will have a specific gravity between the specific gravities of the values and the gangues. Consequently, the gangue will be suspended in, or will float to the surface of the solution and the values will fall to the bottom of the solution. The major problem with the sink-float method for the separation of most minerals is that solution with exact specific gravities must be used and these solutions are not readily available. (c) Jig Plunger Gravity System The jig plunger gravity system of concentration is a variation of the other two systems. Water is used as a foliation device, and a plunger is used to agitate the water to wet the mineral. The mineral is fed into the water, and the plunger, as it moves up and down, increases and decreases the water level, forcing water up through a screen. A separation begins because the specific gravitates of the gangue and the ore differ. The gangue, because it is lighter, tends to remain at the top of the water level, while the ore sinks onto the screen. A stream of water is directed across the top of the water, removing the gangue and leaving the ore to collect on the screen.