Filter presses
Separation of slurries and sludge dewatering: dry cake out, water back into the process. From laboratory testing and cloth selection to an automated line, installation and lifecycle service — chamber, membrane, automatic and vertical presses.
The cloth retains solids while pressure builds the cake
A pump feeds slurry into the closed plate pack. Liquid passes through the filter cloth and drainage channels while solids accumulate in the chambers. In a membrane press, a secondary water or air squeeze reduces residual moisture and cycle time.
Cycle stages: filling → filtration → membrane squeeze → blow-down → cake discharge. Feeding is done with rising pressure: volume first, pressure second — otherwise the cloth blinds at once.
Sludge dewatering and process-water recovery
Five configurations for different duties and cake targets
Classic low-pressure design for small batches in food and pharmaceutical processes.
The most versatile format, commonly 7–16 bar, for water, chemicals, ceramics and stone processing. Without membranes it is simpler and cheaper with lower dry solids; cost-effective on soft cake.
Secondary squeeze can reduce cake moisture by roughly 10–15 percentage points and shortens the cycle by 20–35%; the result must be confirmed by testing. The membrane is a consumable lasting 2–5 years.
PLC-controlled plate shifting, cloth washing, drip trays and cake discharge for high throughput. Mineral plants and continuous duty.
Continuous cloth path and high automation for mineral concentrates and continuous duty.
Chamber depth 15–50 mm and typically 10–200 plates. Final sizing follows batch volume and cycle duty.
By area, pressure and dry solids
- Area, m²
- 5 – 1,500
- Pressure, MPa
- 0.6 – 1.0
- Dry solids, %
- 20 – 35
Cake moisture depends on particle size, cake compressibility, pressure, cloth and slurry conditioning — a guarantee is given only after testing the actual slurry.
Materials follow chemistry, temperature and pressure
Polypropylene is the standard choice up to about 90 °C; glass-filled PP supports higher pressure; PVDF serves aggressive chemistry and higher temperature. Exact limits must follow the manufacturer data sheet.
- Frame: coated carbon steel
- Seals: NBR, EPDM
Welded PP is economical; TPE, EPDM and NBR are selected by temperature and chemical compatibility; PVDF suits special aggressive duties.
- Squeeze pressure up to 16 bar
- Life 2–5 years; squeezing shortens the cycle by 20–35%
PP is the common choice for chemical resistance. PET serves strong abrasive slurries, PES acid media, and PA selected alkaline and elevated-temperature duties. Monofilament cleans and releases cake readily; multifilament retains finer particles. CGR gasketed execution is available.
- Made to drawing or measured plate
- Air permeability 2–60 l/dm²·min, weight 200–800 g/m²
- Calendering, heat setting and edge finishing
- Life 600–3,000 cycles; a blinded cloth doubles the cycle time
Typical specification
| Parameter | Value |
|---|---|
| Dry solids | up to 45% on a membrane press; 25–35% on a chamber press |
| Filtration pressure | 6–16 bar (chamber presses typically 6–12 bar) |
| Squeeze pressure | up to 16 bar |
| Filtration area | 10–500 m² in typical projects |
| Plate size | 250–2,500 mm, typically 630–2,000 mm |
| Cycle | 20–120 min |
| Control | automatic, PLC; variable-speed feed pump |
| Slurry feed pump | up to 16 bar, 2–100 m³/h, solids content 5–40% |
| Hydraulic unit | cylinder with stroke sensor, pump station with accumulator, safety valves, auto re-clamp on pressure drop |
| Safety | light curtain, interlocks |
When a filter press pays off
- Slurries with 5–40% solids
- Clarified water returned to the process
- Less waste volume and lower disposal cost
- Recovery of valuable product from the slurry
What to consider in advance
- Fine colloidal solids without flocculation
- Aggressive solvents — plate material must be selected
- A continuous process with no buffer tank
- Abrasion above the design figure — cloths wear faster
Diagnostics, cloths, plates, hydraulics and upgrades
- Laboratory test: cake moisture, filtrate quality and cycle time
- Installation, commissioning and operator training
- Plate and membrane replacement; PP plate welding after inspection
- Hydraulic, pump, valve and PLC diagnostics
- Upgrades: membrane squeeze, cloth wash and plate shifter
Filter press questions
Chamber or membrane filter press?
A chamber press is simpler and less expensive. Choose membrane squeeze when drier cake, shorter cycles or lower downstream drying and transport cost matter. Confirm the decision by laboratory testing.
What cake moisture can be achieved?
It depends on particle size and shape, cake compressibility, pressure, cloth and slurry conditioning. Chamber presses often fall in a 25–40% range, but a guarantee requires testing the actual slurry.
What data are needed for selection?
Slurry flow, solids concentration, density, particle-size distribution, pH, temperature, target cake moisture, filtrate quality, operating pattern and available footprint.
How is filter cloth selected?
By chemical compatibility, temperature, particle size, filtrate clarity and cake release. Several samples are often compared in a laboratory filter test.
What should the slurry feed pump be like?
Feeding with rising pressure: volume first, pressure second — a hard start at full pressure ruins the cycle. Air-operated diaphragm, progressive cavity or centrifugal slurry pumps are used; abrasive duty needs a polyurethane- or rubber-lined wet end. Typical figures: up to 16 bar, 2–100 m³/h, 5–40% solids, variable-speed drive.
Why do the hydraulics and closing system matter?
They hold the plate pack under pressure for the whole cycle — a leak here spoils the entire batch. On long cycles auto re-clamping on pressure drop is mandatory; a light curtain and interlocks are a safety requirement.
Can an existing press be upgraded?
Yes, after checking the frame, hydraulics and closing-force margin. Upgrades can include membrane plates, an automatic shifter, cloth wash, pumps, instruments and PLC controls.
Do you supply European plates, membranes and cloths?
We supply and service equipment from leading European manufacturers and select compatible spares. Solutions may cover Andritz, Diemme, Metso/Larox, MSE, Netzsch, Matec, Tefsa, Klinkau, Lenser, JVK, Sefar, Clear Edge and Testori, without implying official partnership.
Cloths, selection, water and service
PP, PET, PA and weave type: selecting filter press cloth by chemistry, abrasion, particle size, permeability, cake release and washing.
Open →Choosing a filter pressChamber, membrane, automatic or tower — selecting the press type by slurry, cycle, cake moisture and discharge.
Open →Water treatmentWater as feedstock and water as effluent: treating it to the process requirement and returning the clean water to production.
Open →Service
3DAudit and measurements, installation and supervision, commissioning, planned maintenance, breakdown diagnostics and upgrades.
Open →Need a calculation for this area?
An engineer replies with a selection and specification within one working day.