The so-called work system is some experience summed up through repeated exploration and discussion in the actual production process.

The adjustment factors in jig operation can be divided into two categories:

1. Periodic adjustment factors: Periodic adjustment factors are only adjusted when the washability of raw coal changes significantly.

1) Inclination angle of sieve plate

The function of the inclination angle of the sieve plate is to adjust the discharge speed of heavy products and the density separation time of the bed. The inclination angle of the sieve plate should be determined according to the nature of the raw coal. The inclination angle is appropriate only when the thickness of the bed is kept uniform, that is, it is adapted to the speed of density stratification of the bed. Therefore, for raw coal with good washability, high gangue content and low medium coal content, the speed of density stratification of the bed is fast, and the inclination angle of the gangue section sieve plate should be larger to accelerate the horizontal movement speed of the bed. Because the inclination angle of the sieve plate is small, the movement speed of the gangue layer at the bottom of the bed is slow, which affects the production capacity of the jig; however, for raw coal with low gangue content and high medium coal content and poor washability, the inclination angle of the sieve plate should be smaller. Because if the inclination angle is too large, the bed is not uniform, which increases the loss of screening. In addition, if the inclination angle is large, the horizontal movement speed of the bed is fast, which shortens the separation time and affects the separation effect, and even causes accumulation at the discharge port.

2) Artificial bed

The material layer with a particle size larger than the screen hole and a density greater than the heavy product laid on the screen plate of the jig is called an artificial bed. During the screening and discharging process, the screening speed of high-density particles depends not only on the characteristics of the particles themselves and the movement of water flow, but also mainly on the particle size, density, shape, and thickness of the artificial bed. The screening effect mainly occurs during the period when the artificial bed is already tightly descending under the action of water flow. Therefore, in order to allow all high-density particles that should be screened to pass through the artificial bed and be discharged, the gap between the particles of the artificial bed should be greater than the maximum particle size in the feed. Generally, the particle size of the bed particles of the artificial bed is 3 to 4 times the maximum particle size of the selected material. The density of the bed particles is generally slightly higher than the maximum density of the particles that need to be screened and discharged. If the density of the bed particles is too high, it is not easy to loosen, and the high-density particles in the selected material are not easy to be screened and discharged; if the density of the bed particles is lower than the high-density material that needs to be screened and discharged, the artificial bed is easily replaced by the high-density material in the selected material during the separation process, and a stable separation condition cannot be maintained, and the separation effect is reduced. The thickness of the artificial bed directly affects the screening and discharge speed of high-density materials. Increasing the thickness reduces the screening and discharge speed and improves the quality of heavy products, and vice versa. However, once the thickness is selected, it remains unchanged during the production process. In production operation, the quality of heavy products is adjusted by controlling the strength of the suction force of the descending water flow.