High-efficiency thickener for slime dewatering

2021-07-13

At present, the high-efficiency thickener has become one of the most widely used dehydration equipment in China’s coal preparation plants and ore dressing plants. The GXN and XGN types are more commonly used in China.

The principle and structure of high-efficiency concentration mainly have the following characteristics.

1. Pre-dosing and degassing
The advanced method of dosing is used to pre-add the slurry before the slime water enters the thickener, so that the medicament and the slime water can be mixed more fully. After the slime forms the best flocculation state, it enters the thickener, which improves the flocculation effect and reduces the chemical consumption. Dosing in advance makes the slime water start to flocculate before entering the thickener, which promotes the agglomeration of mineral particles to form large flocs. According to Stokes’ law, an increase in the diameter of agglomerates will accelerate settlement. The particles with small particle size or without flocculation will collide with the flocculation particles during the ascent process and be trapped or hindered, thereby accelerating the settling.

The slime water is pre-degassed before entering the thickener. If the air content in the slime water is large, the air in the slurry will accumulate and be discharged after the material enters the thickener due to the interference of the fluid and the collision of the materials. During the discharge process, some bubbles will adhere to the small particles in the slurry, especially the surface of the hydrophobic ore particles, and carry the ore particles to float up. The floating bubbles have a certain disturbing effect on the formed concentrated layer, which is not conducive to the sedimentation of the ore particles. Pre-exhausting can greatly reduce the interference of air bubbles on the thickening and settling of slime water.

2. Deep deceleration feeding
After the slime water enters the feeding barrel, a baffle or other decelerating device is installed in the feeding barrel to reduce the flow rate of the slurry. At the same time, the feeding barrel extends downward and adopts deep feeding. The deep feeding can greatly shorten the settlement distance of the ore particles. The large and dense flocs that have formed can settle quickly and short distances and form a continuous and stable dense floc filter layer. The unflocculated particles will be blocked when they move with the rising water flow. Lag effect. Deep feeding is conducive to the settlement of ore particles and the clarification of overflow water.

There are two transmission modes for high-efficiency thickeners, namely central transmission and peripheral transmission. The advantage of the central drive is that it can automatically lift the rake when overloaded. After the overload is eliminated, it can automatically reset. The operation is simple and easy to control. However, the drive device of the central drive is more complicated and the force is not as good as the peripheral drive. The entire transmission system of the peripheral transmission is simple, reliable, and low in cost, but the peripheral transmission system requires sufficient friction and is prone to slippage. Measures must be taken to prevent slipping. In production, which transmission method should be used according to the actual situation.