Filter Press Filtration Process: Key Steps Explained

Filtration using a filter press is a highly efficient method for separating solids from liquids. This technique is commonly utilized in industries such as mining, chemical production, and wastewater treatment. This guide explains each step in the filter press filtration process and highlights key phases that maximize efficiency and output.

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1. Filling Phase: Slurry Introduction into the Filter Press

In the first phase, the slurry—a mixture of solid particles and liquid—is pumped into the chambers of the filter press. The chambers consist of a series of filter plates lined with filter cloth. As the slurry enters, solid particles accumulate on the filter cloth, forming a filter cake, while the liquid (filtrate) passes through and is discharged.

2. Compacting Phase: Solid-Liquid Separation

As the chambers fill, the pressure within the filter press increases. This pressure pushes the liquid through the filter cloth, trapping solid particles and forming a thicker filter cake. The filtration efficiency during this phase depends on factors such as the cloth's permeability, the slurry's nature, and the applied pressure.

3. Cake Washing: Removing Impurities from the Filter Cake

For certain applications, washing the filter cake is crucial to remove impurities or recover trapped liquids. During this phase, a washing liquid is introduced through the filter plates, effectively cleaning the cake and enhancing the purity of both solid and liquid outputs.

4. Cake Squeezing: Optimizing Cake Dryness

To reduce the moisture content in the filter cake, some filter presses feature a cake squeezing phase. A membrane inflates inside the plates, applying additional pressure to squeeze out more liquid, resulting in a drier, more compact cake. This step is essential for industries requiring minimal moisture in the solid output.

5. Cake Blowing: Further Drying the Filter Cake

The cake blowing phase involves blowing compressed air through the filter cake to eliminate residual liquid, further increasing its dryness. This step is critical for achieving the lowest possible moisture levels in industries focused on efficient solid-liquid separation.

6. Core Wash and Core Blow: Cleaning the Feed Channels

Over time, the feed channels within the filter press can become clogged with residual slurry or cake material. The core wash flushes these channels with a cleaning liquid, while the core blow uses compressed air to clear any remaining debris. These steps are vital for maintaining optimal filtration performance and preventing blockages.

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7. Cake Discharge: Removing the Filter Cake

Once filtration is complete, the filter press opens, and the filter cake is discharged from the chambers. In most modern filter presses, this step is fully automated, ensuring quick and efficient removal of the dried solids.

8. Cloth Cleaning Systems: Maintaining Filter Cloth Efficiency

After cake discharge, some filter presses are equipped with systems to clean the filter cloths:

• Rinse Wash: This system sprays water over the plates, cleaning the cloth surfaces after each cycle.
• High-Pressure Cloth Washing: A more thorough cleaning, typically performed daily or as needed, utilizes high-pressure jets to remove deep-set particles, ensuring the filter cloths remain efficient for future filtration cycles.

The filter press filtration process is an effective solution for solid-liquid separation across various industries. By understanding key steps such as squeezing, cake washing, cake blowing, and cloth cleaning systems, businesses can optimize the filtration process, enhance efficiency, and achieve higher quality outputs.

If you are interested in learning more about each step of the filtration process, feel free to reach out for any additional information.

Dino Ibba, Regional Sales Director - USA & Canada

+39 366 69 75 963