A sand processing plant reduces the moisture content of sand through a combination of mechanical, natural, and sometimes thermal methods, depending on the required final moisture level (typically 3–8% for construction sand) and production scale. Below are the most common techniques, organized by their working principles and applications:
1.Mechanical Dewatering: Removing Free Water
Mechanical methods use physical force to separate excess free water from sand, which is efficient for reducing moisture from high levels (e.g., 20–30% after washing) to moderate levels (e.g., 10–15%).
● Vibrating Dewatering Screens
- How it works: These dewatering screens have a steep incline (15–25°) and high-frequency vibration. Sand is fed onto the screen surface, where vibration causes water to drain through the screen mesh, while sand particles move forward.
- Key features: Often used after sand washing to remove surface water. Can reduce moisture from ~25% to ~12–15% in one pass.
- Applications: Ideal for medium-scale plants; works well with fine to medium sand (0.1–2 mm).
● Belt Filter Presses
- How it works: Sand slurry is fed onto a porous belt, which wraps around rollers. Pressure from the rollers squeezes water out through the belt, leaving dewatered sand cakes.
- Key features: More effective for finer sand or slurries with high moisture. Can reduce moisture to ~8–12%.
- Considerations: Higher energy costs than screens but better for sticky or clay-rich sand.
● Centrifuges
- How it works: High-speed rotation creates centrifugal force, separating water from sand (heavier particles settle, water is expelled).
- Key features: Efficient for very fine sand or high-moisture slurries, reducing moisture to ~6–10%.
- Limitations: High energy consumption; suitable for small-scale or specialized applications (e.g., high-purity sand).
2. Natural Drying: Evaporating Residual Moisture
After mechanical dewatering, residual moisture (bound to particle surfaces) is reduced using natural air and sunlight, which is cost-effective for large volumes.
● Stockpile Drying
- How it works: Sand is piled in open yards with proper drainage (e.g., gravel bases or perforated pipes). Turning the piles periodically (with loaders or bulldozers) exposes fresh layers to air, accelerating evaporation.
- Key factors: Depends on weather (temperature, humidity, wind). In dry climates, moisture can drop from 12–15% to 5–8% in 1–3 days; in humid areas, it may take longer.
- Cost: Low (mainly labor for turning piles) but requires large land area.
● Drying Hoppers with Ventilation
- How it works: Enclosed hoppers with fans circulate air through sand. Some designs use ambient air, while others preheat air (using waste heat from crushers).
- Advantages: Faster than open stockpiles; less dependent on weather. Reduces moisture from 10–12% to 6–8%.
3. Thermal Drying: For Low-Moisture Requirements
When sand needs very low moisture (e.g., <5% for concrete or glass production), thermal drying uses heat to evaporate bound water.
● Rotary Dryers
- How it works: A rotating drum heated by gas, oil, or electricity. Sand is fed into the drum, where hot air (150–300°C) contacts particles, evaporating moisture. Exhaust air carries away water vapor.
- Efficiency: Rotary dryers Can reduce moisture to 1–3%. Suitable for large-scale plants (100–1000 TPH).
- Cost: Higher energy use (operating cost) but necessary for strict moisture specs.
● Fluidized Bed Dryers
- How it works: Sand is suspended ("fluidized") by hot air, creating intense contact between particles and heat. This speeds up drying.
- Advantages: Uniform drying; faster than rotary dryers for fine sand. Moisture can be reduced to <2%.
- Applications: Smaller-scale, high-precision needs (e.g., foundry sand).
4. Integrated Systems: Combining Methods
Most plants use a multi-stage approach for optimal efficiency:
● Washing + Dewatering Screen: Removes clay, impurities, and free water (moisture ~15%).
● Stockpile Drying: Reduces moisture to ~8% using natural air.
● Rotary Dryer (if needed): Further lowers moisture to <5% for specialized markets.
Key Considerations
● Cost vs. Moisture Target: Thermal drying is effective but expensive; natural drying is cheap but slow.
● Sand Type: Fine sand (e.g., river sand) retains more moisture than coarse sand, requiring more aggressive methods.
● Environmental Factors: In rainy regions, covered stockpiles or indoor drying hoppers are necessary to avoid reabsorbing moisture.
By combining these techniques, sand processing plants can reliably meet the moisture requirements for construction, concrete, or industrial applications. Henan Baichy Machinery Equipment Co., Ltd. is a mining machinery manufacturer integrating R&D, production and sales. Stone crusher is one of its core production equipment. It has mature technology and processes, complete models and configurations, and technical engineers can tailor production line configuration plans for you. If you are interested in the stone crusher, please click on the online consultation to get solution and price now. Baichy Machinery is dedicated to serving you 24 hours a day!
2025-08-20
86-15093113821
86-15093113821
