The vacuum drum filter is a continuously operating filtration device that achieves solid-liquid separation using vacuum suction. It is widely applied in fields such as chemical engineering, food processing, pharmaceuticals, and mining. It is particularly suitable for handling suspensions containing relatively coarse solid particles with high concentrations and certain filterability.

A rotary drum vacuum filter achieves continuous solid-liquid separation through the rotation of a drum submerged in slurry, using vacuum suction to draw liquid through filter cloth and form a filter cake, followed by dewatering, cake discharge, and filter medium regeneration.

Core components

To gain a quicker understanding of how a vacuum drum filter works, let’s first familiarize ourselves with its core components:

It has several particularly important parts, which are just as crucial as the hands and feet of a human being.

A chubby, round rotating drum

It looks like a horizontally placed bucket, wrapped on the outside with a perforated “filter cloth”—just like the filter paper we use for brewing coffee, which lets the coffee liquid seep through while trapping the coffee grounds.

A large basin holding the sludge mixture – Slurry tank

Half of the rotating drum sits submerged in it, and inside is the slurry to be separated—think syrup mixed with sugar residues, or fruit juice with tiny particles floating in it.

The little chambers hidden inside – mesh plate

The rotating drum is divided into many small compartments shaped like “orange segments,” and each compartment has pipes connected to an external “vacuum pump” (the machine that creates suction) and a “blower” (the machine that blows a gentle breeze).

A switchable “valve”

It’s like a clever little switch—when the rotating drum turns to different positions, it connects the compartments either to the vacuum pump or the blower, super flexible!

Working process

As the drum completes one full rotation, each segment-shaped compartment goes through the following 4 stages in sequence, enabling continuous filtration:

First Stage: Filtration – “Sucking Up Moisture” in the Slurry Tank

When a compartment rotates into the area submerged in slurry, the valve connects it to the vacuum pump. Once the vacuum pump kicks in, it acts like a powerful straw, creating strong suction:

Liquid from the slurry gets pulled through the filter cloth into the compartment, then flows away through pipes (this liquid is the “clean filtrate”);
Solids like sugar residues, fruit pulp, or sand get trapped by the filter cloth, gradually piling up into a “filter cake”—like a muddy coat wrapped around the drum.

Second Stage: Dewatering – “Sucking Out Remaining Moisture” After Leaving the Slurry Tank

As the drum keeps rotating, the compartment moves out of the slurry tank, but the vacuum pump stays on—like when you rub your wet hands vigorously with a towel, it sucks out any leftover moisture from the “muddy coat,” making the filter cake drier.
Sometimes there’s a small spray nozzle here, squirting a bit of clean water to rinse the filter cake (say, to wash off dirt from sand particles); the rinsed water gets sucked away by the vacuum pump too.

Third Stage: Cake Discharge – Rotating to the “Discharge Zone” on the Other Side

When the compartment spins around to the discharge position, the distribution valve flips over, connecting that compartment to a compressed air system (or regular atmospheric air). Compressed air blows backward through the filter medium from inside the compartment, loosening the filter cake so it peels away from the medium. At the same time, a scraper next to the drum scrapes off the loosened cake, wrapping up the solid recovery process.

Pro tip: If the filter cake is super sticky, you might need both the reverse air blast and the scraper working together to get it off effectively.

Fourth Stage: Regeneration (Prepping for the Next Cycle)

After cake discharge, the compartment continues rotating. The distribution valve may briefly connect it to the atmosphere or feed in a small burst of compressed air, blowing away any leftover filter cake crumbs to clean the surface of the filter medium—getting it ready for the next trip into the slurry tank for filtration. Some systems also rinse the filter cloth with clean water at this stage to prevent clogging.

Rotary vacuum filter working principle
  • The slurry (mixture of solid and liquid) enters the system via the Feed Inlet. As the Rotary Drum rotates in the direction indicated by “Rotation Direction”, a portion of the drum is submerged in the slurry within the trough. The Agitator keeps the slurry in motion, preventing the solid particles from settling at the bottom, so that a uniform mixture is always available for filtration.
  • Inside the Rotary Drum, there is a Suction Pipe connected to a vacuum source. As the drum rotates, the submerged segments come under the influence of this vacuum. Due to the vacuum pressure, the liquid in the slurry is drawn through the porous surface of the drum (the drum acts as a filter medium support). The liquid passes through and is then directed to the Filtrate Outlet. Meanwhile, the solid particles are left behind on the surface of the drum, gradually forming a solid cake.
  • As the drum continues to rotate, the segment with the formed cake moves out of the slurry. When it reaches the position of the Scraper, the solid cake is scraped off. This scraper is positioned to remove the cake efficiently, ensuring that the drum surface is ready for the next cycle of filtration.
  • After the cake is discharged, the rotated – to position might be subjected to cleaning by the Spray Bar. so that the drum can maintain good filtration performance in the subsequent cycles.

Through the continuous rotation of the drum, the distribution valve alternates connections between each compartment and the vacuum or compressed air systems. This allows the four processes—filtration, dewatering, cake discharge, and medium regeneration—to occur simultaneously at different positions on the drum, enabling continuous solid-liquid separation operations. Its efficiency depends on factors such as drum rotation speed, vacuum level, filter cake thickness, and material properties (e.g., particle size, viscosity).

rotary drum vacuum filter operation

Imagine this: You’re sitting at your desk in the office, or maybe you’re in the break area outside the workshop, and with just your computer, phone, or tablet, you can pull up a live feed of the rotary drum filter in action. With a simple tap or click, you can start, pause, or adjust how the equipment runs—that’s the magic of remote control.

Here’s how it works: The filter links to an intelligent control system, with a clean, user-friendly interface on your device showing function buttons, real-time data (pressure, flow rates, run times), and live feeds. This “remote brain” lets you check status and send precise operation tweaks anywhere in the plant.
Whether you need to adjust settings or monitor from afar, this remote setup puts control at your fingertips, making filter management far more flexible and convenient.
Although remote operation is simple, we’ll provide training for the control equipment. Our technicians will guide you through every interface button—teaching you to read data, adjust parameters, and handle minor issues—until you’re proficient.
Thanks to remote control technology, drum filter operation is now intelligent and effortless. Pre-coating, filtering, and cleaning can all be precisely controlled via computers, phones, or tablets.

Pre-coating diatomaceous earth

Pre-coating diatomaceous earth is like dressing the filter’s drum in a “filtering coat”—this layer ensures cleaner, more efficient filtration. Here’s how you can operate it via the remote terminal:

  • One-click clean water preparation
    Click “Pre-coating Preparation” on the interface to auto-open the inlet valve, feeding water into the slurry tank. The screen shows real-time level, and the valve closes automatically when full—like a cup stopping at capacity.
  • Remote diatomaceous earth mixing monitoring
    Add up to 300kg of diatomaceous earth to the mixing tank. Enter the mixing time (default 10 minutes, adjustable) on the terminal and click “Start Mixing.” A countdown appears as the mixture spins into uniform slurry, blending fully—similar to mixing batter.
  • Start pre-coating & track thickness in real time
    After mixing, click “Open Pre-coating Valve,” “Start Diatomaceous Earth Pump,” “Start Vacuum Pump,” “Start Filtrate Pump,” “Start Drum Motor,” and “Slurry Tank Agitation” sequentially. The drum rotates, and slurry adheres evenly. The screen’s thickness monitor shows real-time levels, with an auto-alert “Pre-coating Complete” once the set thickness is reached—like frosting stopping at the right depth.

filter operation

Once pre-coating is complete, filtration can begin. This step works just like straining juice through a sieve—trapping impurities while letting clean liquid pass through. Operating via the remote terminal makes it even simpler:

  • Switch to filtration mode and start with one click
    Locate the “Filtration Mode” button on the interface. The system will automatically shut down the diatomaceous earth pump and related valves used in pre-coating, while opening the slurry inlet valve. Click “Start Slurry Inlet Pump,” and the dirty slurry to be filtered will enter the equipment, initiating filtration. Real-time data such as filtration duration and filtrate flow rate will display on the screen, keeping you updated on progress at all times.
  • Intelligent monitoring with automatic alerts
    As filtration proceeds, the diatomaceous earth “coating” on the drum surface will gradually thin (due to impurity buildup wearing down the layer). When it reaches the preset minimum thickness, the terminal will pop up a “First Filtration Cycle Complete” alert—similar to a notification when you clear a level in a game. Additionally, if the slurry tank level rises too high, the system will automatically open the overflow valve to prevent spills, requiring no manual intervention.

cleaning operation

After filtration, some residual impurities will remain in the equipment and need to be cleaned before the next filtration cycle. Remote cleaning is incredibly straightforward:

  • Drain residual liquid completely, leaving no “waste”
    Click “Cleaning Preparation” – the system will automatically activate the residual liquid return pump and drain valve，draining all remaining dirty liquid from the equipment. The screen will display “Residual Liquid Draining” until empty, at which point the pump and valve will shut off automatically – similar to siphoning dirty water out when changing a fish tank.
  • Automatic cleaning with repeated “washing” cycle
    Once residual liquid is drained, click “Open Cleaning Valve” to let clean water re-enter the equipment. It will repeat the water cleaning process used during pre-coating, flushing away all internal impurities thoroughly. When complete, the system will indicate “Cleaning Finished,” leaving the equipment as good as new.

The second filtration and circulation operation

For multiple filtration cycles, there’s no need to reset all steps—your remote terminal already has a “shortcut” ready for you:

  • One-click activation for repeated filtration
    After the first filtration cycle, locate the “Nth Filtration” button on the interface (where N represents the cycle number—e.g., click “2nd Filtration” for the second run). The system will automatically repeat all operations from pre-coating (Steps 1–3) to filtration (Steps 5–7), just like hitting a “repeat level” button in a game— the equipment will complete the filtration task to the same standards each time.
  • Full monitoring until task completion
    After each filtration cycle, you’ll see a data report on filtration performance in the terminal. Once all filtration tasks are finished, click “End Process,” and the equipment will automatically run the cleaning cycle (Steps 8–9) before shutting down all operating components. A key note: The device’s electric valves remain closed during “rest”—even after shutdown, they’ll automatically return to this closed “initial state,” much like putting toys back in their box after use to keep everything organized.

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