Abstract:
Even though various kinds of jigs are available in the market for processing gem gravel
obtained from large scale mechanized or hydraulic mining, no portable jigs are available
in the market for the benefit of small scale gem miners in Sri Lanka. In this respect, UNI
-GEM model is unique. It requires only five people to transport it up to a point where
gem pits are located and the same number of men can operate it. The machine was
fabricated using locally available materials.
Jigging is a process by which gravels of different specific gravities of various size range
are concentrated by a stratification process using a pulsating water column enclosed in a
suitable chamber. Effective separations can be obtained with gravels of size less than one
inch. The pulsation frequency and its amplitude have been carefully adjusted to give
an optimum separation. The method is cheap, fool proof and requiring very little
supervision
