Low screening efficiency means qualified fine particles fail to pass through the screen mesh, or coarse particles leak into fine product. This issue frequently occurs in quartz sand production due to quartz’s high hardness, sharp particle shape and tendency to form agglomerates. Systematic troubleshooting should follow the sequence: material → screen media → machine parameters → feeding → auxiliary systems.
Step 1: Confirm The Root Cause By Sampling
First collect three samples to diagnose the problem:
- Feed material to the screen
- Oversize discharge (retained on screen deck)
- Undersize finished product
Run sieve analysis.
- If plenty of fine target particles remain in oversize: poor stratification / screen blinding / overloading
- If coarse grains appear in undersize product: mesh damage, deck seal leakage, excessive material speed
- Both issues exist simultaneously: unstable feed or wrong vibration parameters
Step 2: Material Related Problems & Fixes
- High moisture causes screen blinding (wet quartz sand)
Wet fine quartz sticks together and forms a layer on mesh surface, blocking apertures.
- Solutions: Reduce feed moisture; adopt PU self-cleaning screen panels; install low-pressure water spray for wet screening; add pre-dewatering before screening.
- Excess clay or slime in raw quartz
Clay increases particle adhesion and covers mesh openings.
- Solutions: Pre-wash and deslime before screening; separate slime via hydrocyclone in wet process.
- Overmuch fine powder in feed
Too many ultra-fine particles build a thick mat on screen surface and prevent stratification.
- Solutions: Remove ultra-fines in advance using hydrocyclone; reduce feed rate.
Step 3: Screen Media & Deck Inspection
- Mesh clogging / blinding
- Check mesh surface for packed quartz grains. Replace rigid woven wire with elastic polyurethane panels.
- Mesh abrasion and aperture enlargement
Quartz is highly abrasive. Worn PU or steel mesh creates oversized openings, letting coarse particles leak into fine product.
- Solutions: Inspect mesh daily; use wear-resistant PU panels for medium/fine mesh (40–200 mesh); use manganese steel only for coarse scalping decks.
- Poor sealing between decks / side gaps
Material bypasses the screen surface through gaps instead of passing through mesh.
- Solutions: Replace worn rubber gaskets; tighten fasteners; fix deformed screen frame.
Step 4: Vibration & Machine Parameter Tuning
- Improper vibration amplitude / frequency
- Coarse quartz (4 mesh ~ 40 mesh): Require larger amplitude (3–5 mm). Low amplitude cannot stratify material.
- Fine quartz (40–200 mesh): Medium amplitude (2–3 mm), frequency 18–20 Hz. Too high frequency makes particles bounce excessively and reduce screen contact time.
- Incorrect screen inclination angle
- Too steep: Material runs too fast, insufficient screening time.
- Too flat: Material accumulates, thick material bed.
- Recommended: 5°–8° for fine mesh (40–200 mesh dry screening); 10°–18° for coarse wet screening.
- Uneven excitation force / damaged vibrator
Unbalanced vibration causes uneven material flow across deck width.
- Solutions: Check vibration motors; rebalance exciters; repair cracked frame or broken springs.
Step 5: Feeding System Issues
- Overloading, thick material bed
Fine particles cannot sink through the coarse layer. This is the most common cause of low efficiency.
- Solutions: Reduce feed rate; install vibrating feeder to spread material evenly across full screen width.
- Concentrated point feeding
All material drops onto one spot on the screen deck, creating local overload.
- Solutions: Add feed distribution plate to achieve full-width uniform feeding.
Step 6: Other Auxiliary Problems
- Dry screening: insufficient dust extraction
Floating fine powder forms agglomerates under static electricity. Add negative pressure dust collection. - Material sticking to screen side walls
Reduce static buildup or install wall vibrators.
Quick Reference Troubleshooting Table
| Phenomenon | Likely Cause | Countermeasure |
|---|---|---|
| Lots of fine grains stay in oversize | Screen blinding / overloaded feed / low amplitude | Reduce feed; use self-cleaning mesh; increase amplitude |
| Coarse particles in fine undersize | Worn mesh / bad deck seal / too steep angle | Replace screen panels; re-seal deck; reduce inclination |
| Material piles locally on deck | Uneven feeding / broken springs | Modify feed distributor; check springs and exciters |
| Good at low throughput, poor at high throughput | Limited screen area / too thick material bed | Lower feed rate or upgrade screen size |
Preventive Maintenance Checklist
- Inspect screen panels and seals every shift.
- Check vibration motor current and temperature daily.
- Monitor PSD by regular sieve analysis.
- Control feed moisture and slime content in advance.
Low screening efficiency for quartz sand is most often caused by screen blinding, overloading, worn mesh or poor material stratification. Always start with sieve analysis to identify whether fines are trapped in oversize or coarse grains leak into undersize, then adjust material conditions, screen media and vibration parameters accordingly.
