In the wet separation process of coal washing plants, efficient dehydration is the core link to ensure product quality and reduce subsequent processing costs. As a classic pre-dewatering equipment, the Sieve Bend, with its unique structural design and low energy consumption characteristics, has become an indispensable part of many coal preparation plants. This article will focus on analyzing the influencing factors of the dehydration efficiency of the arc-shaped screen and explore its practical value in the coal washing process.
1.The working principle of the arc-shaped screen
The arc-shaped screen is composed of a set of wedge-shaped screen bars arranged in an arc shape, with an feed particle size of 0-5mm. The coal slurry enters the screen surface along the tangential direction under a certain pressure. Under the action of centrifugal force and gravity:
Solid particles: Due to the effect of inertia, they closely adhere to the screen surface, and water is rapidly discharged through the screen gaps.
Coarse particles: Slide down along the screen surface and enter the next process (such as a centrifuge or vibrating screen)
2.Key factors affecting dehydration efficiency
① Sieve seam size
Coarse particle dewatering: The screen gap should be selected as 0.5-1.0 mm to balance the dewatering volume and the coarse particle running rate.
Fine coal slime treatment: It needs to be reduced to 0.1-0.3mm, but it should be combined with high-pressure water spraying for anti-clogging.
② Feeding pressure and Angle
The optimal feeding pressure is 0.1-0.3 MPa. If the pressure is too low, it will lead to insufficient dewatering; if it is too high, it will accelerate the wear of the screen surface.
The curvature of the screen surface (usually 45° – 60°) affects the retention time of the material and needs to be adjusted according to the viscosity of the coal quality.
③ Material Characteristics
Low-rank coal, due to its high moisture content and high viscosity, is prone to clogging the screen seams. Therefore, it is necessary to clean it regularly or use anti-clogging screen plates (such as polyurethane material).
When the particle size distribution is uniform, the dehydration efficiency can be increased by more than 20%.
3.The core role of arc-shaped screens in coal washing plant
① Pre-dehydration to reduce the load on subsequent equipment
It can remove 30-50% of the surface moisture in the coal slurry, significantly reduce the processing pressure of the centrifuge or filter press, and extend the service life of the equipment.
② Classification and coarse particle recovery
When used in conjunction with a vibrating screen, it can efficiently separate coarse particles larger than 0.5mm and reduce the loss of clean coal.
③ Process flexibility
The modular design supports the rapid replacement of the screen plate, adapting to different coal qualities or production requirements (such as switching from thermal coal to coking coal).
Although the arc-shaped screen has a simple structure, it is the “hidden champion” in the dewatering process of coal washing plants. Through scientific selection and refined management, its efficiency advantages can be maximized.
