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I work for a roofing manufacturing plant and am trying to use recycle water in our cooling section. Currently the water and granules all go down the same drain where we have a loop that circulates all the water back and the granules settle at the bottom. However, I am having trouble filtering the fine sand. I have looked into maybe using a fine mesh to accomplish this, is there any other suggestions?

RE: Filtration

Sand filters are common and can be easily back-washed. A sand filter uses sand as the filtration medium.

RE: Filtration

Thank you Compositepro. I'll look into sand filters. They hadn't crossed my mind.

RE: Filtration

Cyclonic centrifuge. Spins the heavy particles out. great for large volumes of material.

Maybe follows that with a mesh filter. Centrifuges typically get out about 90% of the material.

Thomas J. Walz
Carbide Processors, Inc.

Good engineering starts with a Grainger Catalog.

RE: Filtration

tomwalz, the problem is that 10% left as it is fine sand. The majority of the big material settles at the bottom of a tank.

RE: Filtration

I do not know how happy you are with the tank settling method. Quite often, these things are a real hassle to clean out. In contrast, a centrifuge as the particles in motion is usually fairly easy to put them wherever you want them. A centrifuge can eliminate a lot of clean out time and labor which helps make the whole recycling operation much more attractive.

We have been in the filter system business about 20 years. We usually make filter systems for filtering coolant in precision grinding operations such as carbide tipped tools. We do not have anything suitable for the volume you are generating some of the basics maybe similar.

We typically start a program, such as yours, by having the lab do an analysis of particle count by size wherever we think it is appropriate.

Pretty much in the filtering world there is filtering, finishing and polishing. Filtering is the first operation and removes the great majority of particles. This is what you are doing now with the settling. Then you get into finishing which is a fine filtering operation. The last is polishing which is an even finer filtering operation.

As you move from filtering to finishing and then to polishing the operation gets more and more expensive and removes a much smaller mass of material.

Note: the reason we do several lab tests for particle size and counts is that there really isn’t any reliable standard for rating filters. Several filters that are promoted as identical by their suppliers can give widely different results. Filters need to be properly selected and used.

As an example one of our most common setups is a 25 µ bag filter followed by a 10 µ cartridge filter. This typically removes about 99+ percent of all particles down to one micron.


Thomas J. Walz
Carbide Processors, Inc.

Good engineering starts with a Grainger Catalog.

RE: Filtration

Centriufugal separation ? There are vortex separation systems ... like bagless vacuum cleaners, where a fluid os pumped intoc onneso that it forms a vortex, pushing the particulate or heavier fluid out one end, and the lighter stuff comes out the other. Used to remove solids, and oil/water separation.

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