Design of 1500 tph Coal Crushing and Screening
Introduction
For a large coal crushing and screening station with a capacity of 1500 t/h, equipment selection cannot be determined only according to the rated capacity. It is also necessary to comprehensively consider the maximum lump size of raw coal, target product size, coal quality characteristics, moisture content, fine material proportion, and capacity matching among various equipment. Especially when the maximum lump size of raw coal reaches ≤500 mm, while the final product is required to be controlled at ≤80–130 mm, the reasonable number of crushing stages and equipment configuration will directly affect the capacity, product size, energy consumption, and operating reliability of the entire system.
Core Framework of Process Logic and Equipment Configuration
Two-stage Crushing Process Route
ROM Coal ≤500 mm
↓
Apron Feeder
↓
Primary Mineral Sizer
↓
≤300 mm
↓
Secondary Mineral Sizer
↓
≤80–130 mm
↓
Roller Screen
↓
Belt Conveyor
Primary Sizer undertakes the coarse crushing task from ≤500 mm to ≤300 mm, while Secondary Sizer undertakes the medium and fine crushing task from ≤300 mm to ≤80–130 mm.
Reasonable Crushing Ratio Distribution
The first-stage crushing ratio is 500/300≈1.67, and the second-stage crushing ratio is 300/(80–130)≈2.3–3.75. Although the values do not seem high, the key to coal crushing is not the extreme crushing ratio, but the product particle size distribution, over-crushing rate, and stable processing capacity. The two-stage configuration allows each piece of equipment to operate under optimal conditions, reducing over-crushing and energy consumption.
Equipment Wear and Reliability
If single-stage crushing is used to directly crush 500 mm raw coal to 80 mm, the crushing ratio reaches 6.25. The equipment needs to withstand higher impact and wear, and the toothed roll diameter, torque, and motor power will increase significantly. Two-stage crushing distributes the load, which is beneficial for extending the service life of wear-resistant parts.
Position of Roller Screen
Whether the Roller Screen is arranged before or after the Secondary Mineral Sizer cannot be determined only based on particle size parameters.
Scheme A
Apron Feeder → Primary Sizer → Secondary Sizer → Roller Screen
Scheme B
Apron Feeder → Primary Sizer → Roller Screen → Secondary Sizer
Scheme A is “crushing first and screening afterward”. The Roller Screen is used for final product classification to ensure that the particle size qualification rate of the 80–130 mm product is acceptable. Scheme B is “screening first and crushing afterward”. The Roller Screen is used as a pre-screening equipment to bypass the fine material already smaller than 80 mm in the primary crushed product, allowing only material larger than 80 mm to enter the secondary Sizer, thereby reducing the load and over-crushing of the secondary Sizer.
Both Have Their Own Advantages and Disadvantages
Process Scheme Comparison Table
| Comparison Item | Scheme A: Secondary Crushing Before Screening | Scheme B: Screening Before Secondary Crushing |
| Screening efficiency | Processes the final product, with a large screen surface load | Processes the primary product, and the screen surface load is reduced after fine material is bypassed |
| Secondary crushing load | All ≤300 mm material enters the secondary Sizer | Only >80 mm material enters the secondary Sizer, and the load is reduced |
| Over-crushing rate | Qualified fine particles may be crushed again, increasing over-crushing | Qualified fine material is bypassed, and the over-crushing rate is lower |
| Equipment wear | Greater wear of the secondary Sizer | Less wear of the secondary Sizer, but the Roller Screen needs to process coarser material |
| Energy consumption | Higher energy consumption of the secondary Sizer | Total energy consumption may be lower |
| Adaptability to wet coal | Wet coal fine material entering the secondary Sizer is prone to blockage | Wet coal fine material is screened out in advance, reducing the blockage risk of the secondary Sizer |
For a large coal crushing station of 1500 t/h, if the raw coal already contains a high proportion of ≤80 mm fine material (such as weathered coal and easily crushed coal), the energy-saving and consumption-reduction advantages of Scheme B will be very significant. However, if the raw coal is relatively hard, the proportion of fine material is low, or the final product particle size requirements are strict (high qualification rate within the 80–130 mm range), Scheme A is more reliable, because the Secondary Sizer can ensure that all material passes through the crushing process, avoiding oversize material on the Roller Screen.
Secondary Sizer Tooth Shape and Crushing Gap Design
Tooth Shape Selection
When processing high-moisture and sticky coal, Comb-tooth is recommended. The comb teeth are arranged in a comb shape with a relatively large tooth spacing, and are specially suitable for processing materials with high moisture content and easy adhesion, which can effectively prevent material blockage. Other tooth shapes, such as pointed teeth, are suitable for dry coal with low hardness and weak toughness; blunt teeth are suitable for high-hardness materials; neither is suitable for high-viscosity wet coal.
Mineral sizer, with its unique tooth shape design, has become an ideal choice for processing relatively wet and sticky coal. The spacing between the teeth is designed to ensure that large coal blocks can pass smoothly while preventing small material from passing through. The angle of the teeth has an appropriate inclination, allowing the material to produce a self-cleaning effect during engagement, effectively avoiding blockage caused by long-term adhesion of wet coal.
Crushing Gap Selection
Gap adjustment principle: the gap needs to ensure that coal with the required particle size can fall freely (selective crushing), avoiding secondary crushing, while ensuring that the discharge particle size meets downstream requirements.
For high-moisture or sticky materials, if the gap is too small, material blockage is very likely to occur. When coal moisture increases, the gap or screen opening size needs to be appropriately increased to prevent blockage of screen openings or tooth gaps, but this may reduce crushing accuracy or particle size quality.
For a large Secondary Sizer of 1500 t/h, the crushing gap is usually set between 30–80 mm, depending on the target product particle size and coal quality. If the final product requires 80–130 mm, the gap should be set near the lower limit of the product (approximately 80 mm) to ensure that oversize material larger than 130 mm is crushed, while minimizing over-crushing of material smaller than 80 mm. However, when the coal quality is sticky and wet, the gap may need to be appropriately increased to 90–100 mm to reduce the risk of blockage. The cost is that the upper product limit may be slightly exceeded, which needs to be controlled through subsequent screening.
Tooth Height and Tooth Spacing
The external dimensions of the tooth design include tooth height and tooth width, which are required to be equal to or slightly smaller than the product particle size.
The width of the tooth root is approximately 4/5–1 times the tooth height, and the tooth thickness is generally equal to or slightly greater than the tooth height.
For crushers processing highly sticky coal slime, the tooth width and tooth side gap should not exceed the discharge particle size, and an upper-narrow and lower-wide structure should be adopted to reduce adhesion.
Conclusion
For a 1500 t/h coal crushing and screening station, reasonable system design is not simply connecting high-capacity equipment in series, but requires establishing a complete process matching relationship around the feed particle size, target product particle size, coal quality characteristics, and actual load.
