Coal Preparation Process Design And Screening Equipment Configuration

Efficient coal preparation is essential for improving clean coal yield and optimizing product quality. A well-designed coal washing plant combines classification, separation, and dewatering to ensure both high efficiency and environmental performance. Among all systems, the screening equipment plays a crucial role in separating coal by size and ensuring stable feeding for downstream processes.

1. Raw Coal Characteristics

A typical case from North China is used for design reference. The raw coal has an ash content of 28.5%, volatile matter 23.7%, and total sulfur 0.9%. The particle size distribution is: +50 mm (12%), 50–13 mm (45%), 13–0.5 mm (32%), and –0.5 mm (11%). The designed capacity is 300 t/h, producing lump, fine and flotation clean coal.

2. Process Design

The raw coal is first fed into a GN Large Linear Vibrating Screen (Model GNLS3061) with a 50 mm aperture for primary classification. Oversize coal is crushed by a toothed roll crusher to ≤50 mm. The combined stream passes to a GN Classification Vibrating Screen (Model GNLMP1836) with 13 mm and 0.5 mm apertures for secondary screening:

• +13 mm → heavy medium separation system

• 13–0.5 mm → dense medium cyclone

• –0.5 mm → flotation system

The +13 mm fraction is processed in a shallow-bath heavy medium separator (density 1.55 g/cm³, Ep 0.05–0.07). Magnetite recovery ≥ 98%. Products are rinsed on a GN Dewatering Vibrating Screen (Model GNLMZ1536, 2 mm aperture) for de-medium treatment.

3. Flotation and Dewatering

Fine coal (–0.5 mm) slurry, with a concentration of 100–150 g/L, is treated in a mechanical flotation cell using diesel (80 g/t) and MIBC (10 g/t). The clean coal is dewatered by a GN High Frequency Vibrating Screen (Model GNFG1232) with 0.3 mm mesh, reducing moisture to around 15%.

Dewatering equipment configuration:

• Lump coal → GN Large Banana Vibrating Screen (GNBS3061, 0.5      mm)

• Fine coal → GN High Frequency Screen (GNFG1232, 0.3 mm)

• Slime → centrifuge + filter press (20–25% final moisture)

4. Equipment Configuration Summary

All screens use GN Polyurethane Screen Panels, with opening rates of 28–45% and average service life over 6 months, providing excellent elasticity and anti-blinding performance.

5. Conclusion

This coal processing system, featuring GN’s advanced vibrating screen series (GNLS, GNLMP, GNLMZ, GNFG, GNBS), achieves efficient classification, stable operation, and low maintenance. The optimized screening and dewatering design increases clean coal yield by 3–5% and boosts water recycling efficiency above 95%, meeting the standards of modern coal washing plants.