Analysis of several typical jigging cycles

Sinusoidal relationship between water flow rate and time

In order to raise the bed to the necessary height in the early stage of the rise, a strong rising flow rate is required, but at the same time, the same strong downward flow is caused, resulting in the bed being prematurely tight and shortening the effective sorting time. Reduce the processing capacity of the jig, and due to the strong suction, many low-density ore particles are mixed into the high-density product; due to the long time of the rising water flow, the adverse effect of particle size and shape on the stratification is also increased.

Figure 1 Several typical jigging cycle characteristics used in industry (a) ua>ub, ta>tb; (b) ua>ub, ta=tb; (c) ua>ub,ta

(2) Jigging cycle characteristic curve with large rising water velocity and long acting time

The jigging cycle characteristic curve shown in Fig. 1(a).

The degree of asymmetry in the jigging cycle depends on the amount of water under the screen. During this jigging cycle, the loosening of the bed is beneficial to obtain a strong rising water flow, which improves the processing capacity of the jig. However, due to the long acting time of the rising water flow, it is not suitable for sorting materials of wide granularity and non-grading.

In coarse-grained metal ore sorting is often used such a jigging cycle. The jig may also be used to cycle through a preliminary sorting graded coal (0 · 5 a grain size 13mm).

(3) The jigging period in which the rising water velocity is greater than the falling water velocity but the acting time is equal

During the sinusoidal jigging cycle, the water flow is intermittently given to the submerged water, and the water flow characteristic curve as shown in Fig. 1(b) can be obtained.

The rising water flow of this jigging cycle is weaker than the rising water flow of Fig. 1(a); while the descending water flow reduces the flow velocity, the action time is extended relative to the figure (a), and the sucking effect is slightly enhanced. . Therefore, when processing a wide-grained fine-grained material, it is better than the above two jigging cycles. As China's tungsten, tin ore beneficiation plant process fine grade material jig jig has used this period.

(4) Asymmetric jigging cycle with large rising water velocity but short acting time

The asymmetric jigging cycle as shown in Figure 1(c).

During the intake air, the water flow is pushed by the compressed air and rises rapidly. Then the gas supply is interrupted and there is a short rest period when the water flow is only weaker due to inertia. When the compressed air is discharged, the water flow is reduced by its own weight, so that a descending water flow with a slow time and a long acting time is obtained.

With its treatment in the past domestic and desliming wide grain size or grade coal; foreign concentrator with it a few sorting iron, manganese and zinc ores some lead oxide. This kind of rising water flow is short and fast, and the hopping period is long and slow, and it is not suitable to deal with wide-grain or non-graded materials, whether it is loose, stratified or sucking.

(5) Asymmetric jigging cycle with slower rising water speed but longer duration of action

The rising water velocity is slow, resulting in a slower bed slack process. However, once the bed is loose, the ascending water flow gradually weakens and the shrinking process is slow, which not only prolongs the stratification time, but also during this period, the ore and water flow The relative movement speed between the two is also small, and the particle size and shape of the ore have a weak influence on the stratification by density, so it is advantageous for stratification.

Due to the slow process, the bed should not be too thick, and the processing capacity of the jig is low (6~10t per square meter). The descending water flow rate is fast and the action time is short. From the initial stage of decline, although it is not conducive to stratification by density, due to the slow flow rate and long time at the end of the ascending phase, many coarse and heavy materials have fallen back to the sieve plate. Therefore, participation in stratification activities at this stage is more Fine-grained granules, while the initial stage of decline is the main stage of sucking, so it is beneficial to sorting wide-grain or non-grading materials as a whole; the short-term and slow-speed of water flow is the favorable condition for sorting.

This jigging cycle (see Figure 1 (d)) is suitable for handling ungraded coal.

Practice has proved that the form of jigging cycle curve is one of the important factors to obtain good sorting effect. The reasonable jigging cycle curve should be adapted to the nature of the material selected, so that the bed is in a suitable loose state. The particles mainly move relative to the gravity acceleration difference. This is the basic principle for selecting the jigging cycle curve.

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