Jigging beneficiation is a process in which material is sorted according to density differences, mainly in a vertically elevated, variable speed media flow. The difference in size and shape of the material has an effect on the beneficiation results. The medium used in jigging can be either water or air. When water is used as the sorting medium, it is called hydraulic jigging; when air is used as the sorting medium, it is called wind jigging. At present, the production of hydraulic jigging is the most used, so the content only relates to hydraulic jigging.
The equipment that realizes the jigging process is called a jigger machine. The selected material is fed to the jigger screen, forming a dense layer of material, which is called the bed. While feeding the material, an up and down alternating water flow is fed periodically through the screen plate from the lower part of the jigger, and the material is sorted under the action of the water flow. First, the bed is gradually loosened and suspended under the action of the rising water flow, when the particles in the bed are stratified according to their own characteristics (density, size and shape of the particles) in relative motion to each other. After the end of the upward flow, during the resting period (stop feeding compressed air) and during the downward flow, the bed is gradually compacted and continues to stratify. After all the ore particles have settled on the screen surface, the bed is tight again, and most of the ore particles have lost the possibility of relative movement with each other, and the stratification has almost completely stopped. Only those very fine grains can continue to move down through the gap of the bed (the movement of such fine grains is called drill gap movement), and continue to stratification. After the end of the downward flow, the stratification is temporarily terminated, and the stratification process of one jigging cycle is completed. The stratification process of the material in a jigging cycle is shown in Figure 1. In each cycle, the material can only be subjected to a certain sorting effect, and after several repetitions, the stratification is gradually perfected. Finally, the low density particles are concentrated in the uppermost layer and the high density particles are concentrated in the bottom layer.
The main internal factor for the stratification of the material in the jigging process is the nature of the ore particles themselves, but the objective condition that allows the stratification to occur is the alternating water flow that rises and falls vertically.