Separation of fine and coarse quartz mainly relies on the differences in particle size, settling velocity and fluid resistance between particles. Industrial applications are divided into dry separation and wet separation systems, with screening, air classification and hydraulic classification as the core processes. Below are practical methods, working principles, equipment and application scenarios in detail:
1. Screening / Sieving (Most Basic & Widely Used)
Different mesh sizes of screens block coarse quartz particles on the surface, while fine quartz particles pass through the screen holes. It is suitable for materials with obvious particle size differences.
Main Equipment & Operation
- Vibrating Screen The most common equipment for quartz grading. Equipped with multi-layer screen decks with different aperture sizes to realize multi-stage classification. Coarse quartz stays on the upper screen, and fine quartz falls to the lower layer or discharge outlet. Tips: Select screen aperture strictly according to the required particle size boundary; keep uniform feeding to avoid screen blocking and reduced efficiency.
- Trommel Screen (Rotary Screen) Used for pre-separation of raw quartz ore with large output. The rotating cylindrical screen separates bulk coarse quartz and fine quartz sand, mostly applied in the front process of quartz production lines.
Applicable Range
Ideal for separating coarse quartz gravel and fine quartz sand (particle size generally above 100 μm). Simple operation, low cost and large processing capacity.
2. Air Classification (Dry Air Separation)
Use high-speed airflow to generate drag force. Coarse quartz particles have larger mass and fall down under gravity; lightweight fine quartz particles are carried away by airflow, realizing dry grading.
Main Equipment
Turbo Air Classifier / Centrifugal Air Separator, usually matched with grinding equipment (ball mill, jet mill) for closed-circuit production.
Operation & Features
- Adjust the rotor speed and air volume to control the separation particle size: higher rotor speed produces finer separated powder.
- The whole process is dry, no water consumption, no secondary pollution. No follow-up dehydration and drying procedures are needed.
Applicable Range
Perfect for dry fine quartz powder (micron-level fine quartz). Solves the problem that ultra-fine quartz agglomerates and cannot be fully separated by ordinary screening. Widely used in high-purity quartz powder, electronic grade quartz and fused quartz production.
3. Hydraulic Classification (Wet Separation)
Based on Stokes’ settling law: quartz particles of different sizes have different settling speeds in water. Coarse particles settle rapidly to the bottom, while fine particles suspend or settle slowly in the water, so they can be separated by intercepting different flow layers.
Common Equipment & Processes
- Spiral Classifier Matched with wet ball mills in closed circuit. Coarse quartz sand is sent back to the mill for re-grinding, and fine quartz slurry flows out as finished material. Mainly used in quartz sand processing lines.
- Hydrocyclone Efficient fine grading equipment. Under strong centrifugal force, coarse quartz is discharged from the bottom sediment outlet, and fine quartz slurry overflows from the top. It features small footprint, fast separation speed and high precision.
- Hydraulic Sizing Tank Continuous multi-stage water tank grading, suitable for producing multiple particle size fractions of quartz sand.
Features
- High grading accuracy; meanwhile, it can remove mud, dust and impurities attached to quartz particles to improve product purity.
- Disadvantage: The separated fine quartz slurry needs subsequent dewatering, filtering and drying processes.
Applicable Range
Wet-process quartz sand, high-purity quartz raw material, and fine quartz that is easy to generate dust.
4. Combined Separation Process (Industrial Preferred)
For high-capacity and high-precision production, multiple processes are combined to improve separation efficiency:
- Coarse pre-separation: Raw quartz → Trommel screen / Vibrating screen (remove large coarse quartz)
- Fine grading: Screened fine material → Hydrocyclone / Air classifier (precision separation of fine quartz)
- Post-processing: Wet process → Dehydration + drying; Dry process → Dust collection and finished product collection
Selection Guide for Different Scenarios
- Separate large-grain coarse quartz and ordinary fine quartz sand: Vibrating screen / Trommel screen (priority)
- Produce dry ultra-fine quartz powder: Air classifier
- Produce high-purity quartz sand with impurity removal: Hydraulic classification (hydrocyclone + spiral classifier)
- Large-scale formal production line: Adopt screening + air/hydraulic classification combined process
