Section 01
Overview
Sand and industrial-mineral processing is deceptively simple: separate the value mineral from the water and the unwanted fines. The complexity is in doing it cleanly at high throughput with low water consumption — especially in water-scarce regions where the industry has historically been most cost-pressured.
Cathay's sand-processing equipment line is engineered for closed-circuit operation: water leaves the washer carrying fines, fines settle in the thickener, clear water returns to the washer. Closed-circuit operation cuts process water demand by 90-95% compared to open-circuit washing — the difference between needing 2.5 m³ of fresh water per tonne of sand produced versus 0.15 m³.
Reference deployments span sand-washing for ready-mix concrete supply, frac-sand production for oil/gas drilling, and industrial-mineral processing (kaolin, feldspar) for ceramics. Each plant is sized against actual market demand patterns rather than rated capacity.
Cathay's sand-processing equipment line is engineered for closed-circuit operation: water leaves the washer carrying fines, fines settle in the thickener, clear water returns to the washer. Closed-circuit operation cuts process water demand by 90-95% compared to open-circuit washing — the difference between needing 2.5 m³ of fresh water per tonne of sand produced versus 0.15 m³.
Reference deployments span sand-washing for ready-mix concrete supply, frac-sand production for oil/gas drilling, and industrial-mineral processing (kaolin, feldspar) for ceramics. Each plant is sized against actual market demand patterns rather than rated capacity.
Section 02
Operational Challenges
**Water cost + availability.** In arid regions (North Africa, Middle East, parts of Australia), municipal water cost can exceed $1/m³. Borehole capacity is often limited. Open-circuit washing is economically and physically impossible at scale.
**Fines management.** The fines (clay, silt) removed from the sand have to go somewhere. Settlement ponds work for small operations; thickeners + filter presses are required for industrial scale. Increasingly, the fines themselves are a saleable product (filler aggregate, soil amendment).
**Product specification variance.** Frac-sand requires tight roundness, sphericity, and crush-strength specifications. Concrete sand needs fines content control (Zone 1, 2, or 3 per spec). Industrial kaolin requires brightness and particle-size distribution. Same washer architecture, different screen + classifier configurations.
**Marine vs. fluvial sources.** Marine sand contains chlorides (must be washed to remove for concrete use). Fluvial sand contains organic matter (must be washed for ceramics). Wash water chemistry varies; equipment selection follows the source.
**Fines management.** The fines (clay, silt) removed from the sand have to go somewhere. Settlement ponds work for small operations; thickeners + filter presses are required for industrial scale. Increasingly, the fines themselves are a saleable product (filler aggregate, soil amendment).
**Product specification variance.** Frac-sand requires tight roundness, sphericity, and crush-strength specifications. Concrete sand needs fines content control (Zone 1, 2, or 3 per spec). Industrial kaolin requires brightness and particle-size distribution. Same washer architecture, different screen + classifier configurations.
**Marine vs. fluvial sources.** Marine sand contains chlorides (must be washed to remove for concrete use). Fluvial sand contains organic matter (must be washed for ceramics). Wash water chemistry varies; equipment selection follows the source.
Section 04
Typical Plant Setup
A representative 150 t/h closed-circuit sand-washing plant:
1. **Vibrating feeder** with attached pre-screen — removes >40 mm oversize.
2. **Twin-shaft log washer** — primary attrition wash on clay-bound feed.
3. **Spiral sand washer** (twin spiral) — secondary wash, primary classification.
4. **Two-deck vibrating screen** — splits washed product into 0-2 mm fine sand and 2-10 mm coarse sand.
5. **Dewatering screen** on fine-sand stream — drops moisture to <12%.
6. **Thickener (10 m diameter)** — settles fines from spent wash water.
7. **Clarified-water tank** — buffer tank for return water to washer.
8. **Flocculant dosing station** — auto-controlled by turbidity sensor.
9. **Underflow pump** — moves thickened fines to filter press or fines stockpile.
Water consumption: 8-12 m³/h fresh make-up. Recovery rate: 94%. Total connected power: ~180 kW. Site footprint: ~40×30 m. Commissioning: 5-7 weeks.
1. **Vibrating feeder** with attached pre-screen — removes >40 mm oversize.
2. **Twin-shaft log washer** — primary attrition wash on clay-bound feed.
3. **Spiral sand washer** (twin spiral) — secondary wash, primary classification.
4. **Two-deck vibrating screen** — splits washed product into 0-2 mm fine sand and 2-10 mm coarse sand.
5. **Dewatering screen** on fine-sand stream — drops moisture to <12%.
6. **Thickener (10 m diameter)** — settles fines from spent wash water.
7. **Clarified-water tank** — buffer tank for return water to washer.
8. **Flocculant dosing station** — auto-controlled by turbidity sensor.
9. **Underflow pump** — moves thickened fines to filter press or fines stockpile.
Water consumption: 8-12 m³/h fresh make-up. Recovery rate: 94%. Total connected power: ~180 kW. Site footprint: ~40×30 m. Commissioning: 5-7 weeks.