What Is a Plate and Frame Filter Press?

Plate and frame filter presses have been utilized for decades across various industries to efficiently separate solid and liquid components. Understanding how these versatile machines work provides key insights into their many applications.

In this comprehensive guide, as a professional plate and frame filter press manufacturer, we’ll explore what exactly plate and frame filter presses are, what components and types there are, and the wide range of processes where they add tremendous value.

What Is a Plate and Frame Filter Press?

A plate and frame filter press is an industrial machine used to separate liquids and solids through pressure filtration. It consists of a series of rectangular plates and frames that alternate and clamp together to form hollow chambers.

The plates are usually covered with filter cloths, with a fixed perforated drainage surface. The liquid feed containing suspended solids is pumped into the chambers under pressure. It passes through the filter cloths, while the solid particles accumulate on the cloth surface.

The clarified liquid, called the filtrate, flows through the perforations in the plates and is collected in a pipe or channel system. The filter cakes form on the plates and keep building in thickness until they completely fill the chambers.

This efficient separation process is accomplished without belts, screws or agitating devices. It relies solely on applied hydraulic pressure against a filtering medium.

Components Of a Plate and Frame Filter Press

While there are variances between models and makes, most traditional plate and frame filter presses share several common components:

• Filter Plates: These are rectangular plates usually made of polypropylene or stainless steel. They alternate with hollow frames to form filter chambers and support the filter cloths.
• Filter Frames: The frames separate the plates and create hollow chambers where filtration occurs. Their depth determines the filter cake thickness.
• Filter Cloths: Special cloths (often made of polypropylene or cotton) line the chamber plates to collect solid particles and allow liquid through.
• Base Frame: A rigid steel frame houses the filter plates and provides structural integrity.
• Side Bars: Guide bars on the sides of the filter press enable opening and closing of the unit.
• Head Piece: This end piece features inlets and outlets to pipe in slurry feed and take away filtrate.
• Pressing Device: A ram or hydraulic cylinder exerts pressure against the plates for filtration.
• Cake Discharge: Pipes fitted with valves at the base allow fast discharge of filter cakes upon opening the press.

How Does a Plate and Frame Filter Press Work?

The working principle of a plate and frame filter press involves the following:

1. Filling: The filter chambers fill as slurry is pumped in under pressure through a pipe inlet in the head piece. Suspended particles get trapped on the filter cloths lining the chamber plates.
2. Separation: The liquid gets squeezed through tiny pores in the filtering cloth media. Clean filtrate passes into the chamber frame space and exits through corner ports into a collection pipe network.
3. Cake Formation: Filter cakes continue building on the cloths until preset pressure limits are attained. The feed pump turns off once the chambers are filled with compressed solids.
4. Cake Release: After draining residual liquid, the side bars lower to open the unit. Filter plates shift apart and filter cakes slide off, falling into collection bins below.
5. Cloth Cleaning: Once all solid particles discharge, the filter cloths wash to prepare for the next filtration cycle.

This sequence efficiently separates crystal clear liquid from a muddy slurry mixture without backwashing or aids like filter paper.

Types Of Plate and Frame Filter Presses

While sharing a similar filtration concept, plate and frame filter presses come in different configurations to suit specific applications:

Recessed Plate Filter Press

As the name suggests, this press style features plates with recessed chambers instead of hollow frames. Filter cloths drape into the recesses to collect particles. Models utilize gaskets or “self-gasketing” cloths to minimize leakage. These allow cake build-up in controlled thicknesses but don’t facilitate cloth change-outs.

Chamber Filter Press

Chamber filter presses have deeper recesses, allowing much thicker filter cakes. They handle higher feed solids and greater hydraulic pressures than conventional plate and frame types. Change-out of filter cloths is relatively difficult however.

Membrane Plate Filter Press

Membrane plate and frame filter presses utilize specialized membrane plates instead of filter cloths. The membranes demonstrate precise filtration down to 0.1-micron levels. This exceptional performance comes at a higher cost of membrane plates.

Fully Automatic Filter Press

These utilize electro-hydraulic or electro-mechanical drives for remote control of all filtration steps. Programmable automation allows feeding, squeezing, drying, and cake discharge with minimal operator intervention. Energy-savings from shorter cycle times offset higher equipment costs of fully automated presses.

Key Benefits Of Plate and Frame Filter Presses

• Achieve efficient solid-liquid separation without centrifuges or vacuum filters
• Flexible operation across a vast viscosity range – from crystal-clear water to pasty pulps up to 600 g/l dry solids
• Handle mild as well as strongly acidic/alkaline slurries from 3 pH to 13 pH
• Compact, space-saving footprint with high yields up to 40 kg/m2/hrfiltration
• Utilize automatic pressure holding to maximize cake dryness
• Optionally integrate proprietary optimization for demanding separations
• Simple interface and control compared to traditional rotary vacuum drum or horizontal belt filter press
• Easy inspection and maintenance access to wetted parts
• Varied filtration areas – from 0.25m2 to 300m2 filter press models
• Economic price point for small enterprises

In essence, traditional plate and frame filter press technology continues to prove itself as an efficient and versatile liquid-solid separation method across countless industries. From metal finishing lines to chemical plants, these unassuming machines drive maximum yields and minimum waste generation.

With Increased automation and breakthroughs in filter plate and cloth durability, the reliable plate and frame filter press retains its competitive edge against more sophisticated (and far more expensive) alternatives.

Whether producing silica sludge from semiconductor wafer sawing operations or extracting valuable biodiesel catalyst from effluent streams, the plate and frame press frequently emerges as a front runner during initial selection stages.

Progressive optimization of operating parameters and adaptation to specific process characteristics further cement its prominence as the separation tool of choice.

Typical Applications Of Plate and Frame Filter Presses

Now that we’ve covered the basic mechanism and benefits, you’re probably curious what types of processes typically employ these filter presses:

• Mineral Processing: Extract precious metals, clarify mining slurries
• Pharmaceuticals: Harvest enzymes, antibiotics; Purify active ingredients
• Chemical Production: Isolate pigments, catalysts and coagulants
• Food Processing: Clarify wines, juices and oils; Produce pectin, alginates
• Biofuels: Recover enzyme catalysts; Process algal sludge and residues
• Wastewater Treatment: Thicken biological sludge; Harvest alum solids
• Metal Finishing: Remove heavy metal hydroxides from rinse water
• Pulp & Paper: Bleach plant effluent; Paper coating clay
• Textiles Industry: Size recovery from textile effluent
• Oil Drilling: Process oil-contaminated solid wastes
• Steel Mills: Treat rolling emulsion and hydroxide sludge
• Brewing Industry: Filter kettle trub and recover yeast

It’s quite clear that the conventional plate and frame filter press provides tremendous utility across a vast spectrum of liquid-solid separation duties.

After a century of done-and-dusted reliability, this unassuming “newcomer” pressure filter continues gaining ground against far more sophisticated alternatives that cost multiples more.

From huge minerals dewatering to pilot-scale fine chemical recovery and everything in between, the plate and frame filter press frequently emerges the separator of choice during initial stages.

Conclusion

So in summary, a traditional plate and frame filter press is an elegantly simple, yet versatile industrial machine for liquid-solid separations. It uses hydraulic pressure – instead of gravity, vacuum or centrifuges – to squeeze clean liquid through specialized cloths, leaving solid filter cakes.

Constructed from rectangular plates and frames stacked upright in alternate sequence, it forms isolated hollow chambers that fill under pressure with a liquid-solid feed mixture.

Crystal-clear liquid gets forced out through tiny pores in the filtration cloth as chamber plates compress together. This clarified liquid, called the filtrate, exits through corner ports into external discharge pipes.

Meanwhile, suspended particles accumulate continuously on the filter cloth surface inside each chamber space. These filtered solids compact into solid blocks that continue building in thickness until the chambers completely fill.

The formed filter cakes discharge once the press opens, and the cycle repeats. This efficient, enclosed separation concept is applied for numerous dewatering, recovery and purification processes across a wide spectrum of industries.

From minuscule catalytic particles to bulky biological sludge, the versatile plate and frame filter press handles separations across a vast particle size and viscosity range. Manual, automatic and fully automated variants enable customization to each application for optimal yields.

Progressive enhancements in filter plate seals, chamber depths and discharge configurations cement its reputation as an economical, user-friendly solution for challenging solid-liquid separation needs.