Horizontal Screw Concentration Filtration Centrifuge

The Horizontal Screw Concentration Filtration Centrifuge is a continuous solid-liquid separation machine designed to treat low-concentration suspensions and slurries with fluctuating solid content.

It is primarily applied in chemical processing, salt production, and industrial mineral processing, combining pre-thickening, filtration, washing and dewatering in one continuous machine.

Concentration Zone

• Solid settling mechanism: Suspension enters the scroll cavity via the feed pipe and flows into the outer drum's sedimentation section. High centrifugal force causes solid particles to settle against the drum wall, forming a pre-concentrated solids bed.

• Liquid clarification: The clarified liquid phase overflows through discharge ports located in the sedimentation section, reducing hydraulic load on the downstream screen section and stabilizing filtration performance.

• Fine particle recovery capability: Pre-settling fine particles before screen exposure retains fine solids that would otherwise pass directly through screen openings, improving overall process yield.

Filtration Zone

• Screen filtration process: Pre-concentrated solids are moved axially by the scroll conveyor into the screen section of the drum.

• Cake formation: Solids accumulate on the inner surface of the screen basket to form a uniform filter cake.

• Further moisture removal: Centrifugal force drives remaining liquid through the cake layer and screen apertures, achieving low final moisture levels.

Screw Conveying Zone

• Differential Speed: A planetary differential gearbox sets the speed difference between drum and scroll, adjustable from 10 to 60 rpm.

• Continuous solids discharge: Helical scroll flights convey dewatered solids continuously toward the discharge port while maintaining uniform material flow.

Note: Our company can customize production according to user requirements.

Solids Recovery: 95–99% for solids above 0.05 mm, with 1–3 wt% solids in the overflow and screen filtrate, which can be recycled to the feed.

Cake Moisture: Typically 3–6% for salts such as NaCl and ammonium sulfate, and 10–15% for fine minerals or gypsum. About 2–5 percentage points wetter than a pusher centrifuge on the same crystals.

Differential Speed Effect: Lower differential speed gives a drier cake and longer residence time; higher differential speed raises throughput but thins the cake and increases moisture.

Washing: Spray nozzles wash the cake on the screen, with typical displacement efficiency of 70–90%. Because the cake keeps moving, washing is less thorough than in a pusher or peeler centrifuge; for high-purity products, choose those instead.

Feed Solids: 5–50 wt%, best at 10–40 wt%. Feed fluctuations of about ±30% are absorbed by the sedimentation zone, so no buffer tank is needed for most duties.

Particle Size: Solids of 0.05–3 mm are retained on the screen. Fines of 10–50 µm are partly captured in the sedimentation zone, but particles below 10 µm mostly leave with the overflow. Recovery depends on the density difference and is confirmed by a sample test.

Slurry viscosity & characteristics: Compatible with standard aqueous suspensions, salt slurries, chemical crystal slurries, and industrial mineral suspensions.

Operating Temperature: Up to 80°C with standard FKM seals; up to [120]°C with PTFE or graphite seals and titanium or duplex construction.

Crystal or amorphous solids suitability: Suitable for crystalline salts, fibrous solids, and fine chemical intermediates requiring pre-thickening.

Screen types: Precision wedge wire screens or perforated screens matched to process particle geometry.

Aperture selection: Aperture sizes from 0.05 mm to 0.5 mm (typical 150-mesh configuration available) are customized based on laboratory particle size analysis.

• SS304: Standard stainless steel for non-corrosive, neutral pH industrial slurries.
• SS316L: Acid-resistant grade for organic acids and mild chemical media.
• Duplex 2205: Standard construction material for high-strength drum bodies, providing resistance to chloride stress-corrosion cracking.
• Titanium TA2: Chloride brines, seawater and oxidizing acids. Not suitable for hydrochloric acid, fluorides or dry chlorine; use Hastelloy C-276 for those duties.
• Wear Protection: Scroll flights are hardfaced with tungsten carbide or fitted with replaceable carbide tiles; screen baskets are available in wear-resistant wedge wire. Wetted parts are supplied with EN 10204 3.1 material certificates.

Incoming material inspection: Chemical analysis and mechanical property verification of wetted alloy plates and forgings (SS316L, Duplex 2205, Titanium TA2).

 

CNC machining: Precision CNC machining of drum hubs, scroll shafts, and main bearing housings to strict engineering tolerances.

 

Welding procedures & NDT: Non-destructive testing (PT/UT) conducted on structural welds of steel bases and stainless drum assemblies.

 

Dynamic balancing: Independent dynamic balancing of both the outer drum and inner scroll conveyor performed according to ISO 1940 standards.

 

Assembly spin testing: Pre-shipment factory testing covering vibration analysis, sound level measurement, and bearing temperature stabilization.

 

1. When should I choose a screw sedimentation-filtration centrifuge?

Choose this model when solids content varies or falls below 35 wt%. Its sedimentation zone can absorb fluctuations of about ±30%, while a pusher centrifuge typically requires a steady 40–60 wt% feed. For cake moisture below 3% and higher purity, a pusher centrifuge is usually better.

2. How does differential speed affect moisture and throughput?

Reducing differential speed from 40 to 15 rpm typically lowers cake moisture by 1–3 percentage points but reduces capacity by 30–40%.

3. How much solid is lost to the filtrate?

Recovery is typically 98–99% for particles above 0.1 mm and 85–95% for 20–50 micron particles. Filtrate solids are usually 1–3 wt% and can be recycled to the feed tank.

4. What cake moisture can I expect?

Typical results are 3–6% for sodium chloride, 2–4% for ammonium sulfate, 10–15% for FGD gypsum, and 15–25% for coal fines.

5. How much wash liquid is needed?

Use 0.1–0.25 kg of wash liquid per kilogram of dry solids to remove about 70–90% of mother-liquor impurities.

6. How long do the screen and scroll last?

Wedge-wire screens typically last 6–12 months in abrasive service and 18–24 months with salts. Carbide-hardfaced scroll flights last 2–4 years, compared with about 1 year without protection.

7. What is the maximum operating temperature?

Standard FKM seals support temperatures up to 80°C. Above 80°C, PTFE or graphite seals with titanium or duplex construction can extend the range to about 120°C.

8. What do you need for sample testing and a quotation?

Please provide 20–50 L of slurry, particle-size data (D10/D50/D90), solid density, feed-solids range, temperature, pH or chloride content, target capacity, and target moisture.

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