Screen Separator Underneath Water

Why do you need it under water? It would be much cheaper and simpler to make if not in the water. If dust is a problem either enclose it with a dust collector or a fine mist waster nozzle spraying over the dust producing area.

About 90 years or so in the USA greenhouses and florists began to made something like what you are describing but dry. It consisted of a wooden body, about 5 feet tall 2-3 ft wide and 5-6 ft long. It was fed from the top. The dirt then fell onto a screen which was being shaken and fall down onto the floor. Particle size was dependent upon the mesh size of the screen. The screen was shaken by an electric motor driving a flat belt The belt drove a flat pulley mounted on a Model "T" Ford crank shaft. A connecting rod from the ford engine was connected to the shaft and the screen body. Run the motor and the dirt/stones were screened.

There are commercial units for sale from the home handyman garden size to semi-trailer mounted units. These are not underwater types but you should look into them for modification.

Good Luck, Old Salt

Hi,

This is not clear.

Are you separating sand from gravel before introducing it into a helix sand washing machine?

More detail is in order here.

Thanks for your reply...and, as allways, you are correct Lyn !!! The row material is coming with gravel, sand, silt, clay and moisture !!! In order to separated them I would like to locate the conventional 3 horizontal screen machine into the water !!!

In fact, the screen will be in the same "housing" than the helix...."rear extention"

Again....operativally...wich could be the problem ???

Excuse my english

The effectiveness of the separator will be diminished. It won't work as well as if the material is dry.

If it is already wet, it might be better to dry it before separation.

My guess is that you want to get rid of the clay and silt, or do you want to separate into gravel, sand, silt and clay?

So,

1. Is it wet or dry?

2. How much is there? How much per hour?

3. Can you dry it first? How long will it take to dry x tons per hour?

4. Do you wish to separate it wet?

5. What do you want to keep, gravel, sand, silt, clay?

Lyn,,,everybody...Dry is tremenous expensive...I just want to keep the sand and gravel...clay and silt will go away "floating" on the water. Sand and gravel will be use in construction.

Imagen a "huge steel box", with special geometry, almost full of water....and the beginig the raw material will discharge over the screen ,...the gravel will be taken off avoiding go into de helix...only sand will go trougth it.

With all due respect.....imagen what could happen if you use a screen separator under the water ? the material will not settle ???...or what ???

I will try to attach a drawing though this forum

Thanks

Given proper agitation and/or flow it would work, no doubt.

That's what sluice boxes do.

Unless I'm missing something, you haven't yet told us what the problem is.

Hello, when you say underwater, do you mean at the bottom of a lake... perhaps the sea... or a tank? Besides the oxidising effect of water on the structure (and contamination with FeO2, grease, etc), suspended particles will probably get more easily into moving parts (joints, bearings) reducing their life in service. The transmission of energy from motors will also be an issue... Why should the separation of the different constituents of your raw material be easier if screened underwater. If separation is an issue, and you want to use water in the process, you can use tanks for separating materials that float from those that don´t, perhaps a centrifuge or filters will help in the process!. Drying (solar power, steam, electricity) the resulting material and sieving it can also be a part of the final process. A thorough explanation of what you have in mind will certainly help us to lend you a hand in your project. Saludos desde Buenos Aires ! (Greetings from Buenos Aires)

There was additional info posted while I wrote this reply

Hola..I better star all over again...
Just imagen you would like to make this machine (screen sand-gravel separator) work underneath the water...inside a tank !!!!What could happen ?

As you can see, there is no movil parts underwater...the engine it's up above...the water is quiet, meaning no presion.

I would like to do it in this unusual way because the screening vibration make attrition, wich is the best way to make the clay un-bound the particulate.

Seria sensacional poder escribir en español !!!

Thank you guys very much

I would go for a rotary screen like this one:

In which water can be used to do the first part of the process. After drying, the material can be processed using a regular sand-gravel separator.

Another alternative could be to use a series of tanks where the heaviest part (sand) precipitates, and the undesired stuff (in suspension) can be washed away. The dry sand can then be processed by a separator.

The remaining question is if it makes sense to use such expensive methods if sand will be used for construction. It probably would make more sense to get the raw material from another source

Hola...we had tried to do it with trommel (rotary unit); it was very unefficient.

Part of the project it's to produce in a row, meaning, not stop or wait for drying.

The nearest place to get good quality sand from here is 120 Miles away !!!

We have all the equipment....and the idea to innovate putting the screen underwater....dougthing if something could be wrong.....mechanically.

There is a rule to write in english in this forum ???

Thank you for your time

You should review the CR4 Rules of Conduct:

1. CR4 is an English-speaking community. As such, all content must be posted in the English language so that it is accessible to this audience and can be reviewed properly. At the same time, it is important to note that for many users of this site, English is a second language. Therefore, there is no reason to report, highlight, or denigrate grammatical errors, typos, etc. It is also against this site's policy to denigrate a user because of his or her location, race, gender, or creed.

You dont make sense.

If you want dry material coming out in a constant stream but you put the seperation under water your material coming out will be wet.

120 miles for sand does not seem much dependent on how much you need and what for.

Not my area, but:

1. How would you remove the sifted products from the tank?

2. Won't the clay + water produce mud? What do you do with that?

Thanks bigg for your explanation; usefull for me.

All the material setlle at the botton of the tank, will be "push" with a couple of high pression fluids toward the Helix equipment

The sand and the stones won't be as big a problem as the clay. Clay is very hard to dig wet or dry. It clogs up equipment very easily. Clay is so thick that it is mixed with water to a high density of clay and shipped in tank cars. It stays in suspension due to this thickening. Clay on the surface is what makes paper glossy, have you ever seen it on paper? It is so thick it looks like a layer. Clay is also used to make rheological compounds. These are added to other compounds such as make-up, paints, adhesives and other products. Not the stuff to play with.

Good Luck, Old Salt

It was not lost on all of us.

It didn't seem to matter to the OP.

It will not work. How do you expect the transport from under the screens to happen?

I would seperate the processes as in: Washing, drying, screening, screening, screening.

What about this method?

http://en.wikipedia.org/wiki/Cyclonic_separation

Good Day Yumasq. I'm having a little trouble visualizing this set-up. Are you talking about submersing this sifter in a relatively stagnant pool of water or will there be constant flow through the container? If relatively low water flow, I would expect the vibration/motion of the sifting unit to induce a lot of waves leading to turbulent water which will tend to suspend a lot of the material and void the sifting action (think of trying to wash in dirty bath water). If water is flowing through the container, I would expect that you would entrain some of the particles and bypass the sifting operation all together (unless the unit is not submersed and you are proposing to just make a water based slurry and run this through the sifter). As was noted previously, clay has some amazing suspension properties, when a small amount of deflocculant is added, you get clay slip which is used extensively in the ceramics industry for casting plates, cups, vases, and those "high quality" souvenirs. This material has a very high specific gravity and will hold other particles in suspension. Regards.

Thank you all for your valuable oppinion...I can conclude that the main problem could be the not setlle of the material.

I most say that the screen machine work with 1,000 RPM and 3/8" amplitud, which mean that do not create weaves.

I allready made a test, putting a little screen into a pool...work perfect !!

At the very botton of the screen, there is a high presion- low volumen fluid to "sweep" the very little sand (-70)

Please....beside the not-setllement (wich not happen)...could be another problem ???

Thank you all

So far, I still believe that the best idea is to buy a really BIG truck as it will be far cheaper to transport the sand these 100 miles you mentioned, than using any machinery to sieve wet sand mixed with clay!

Have you considered a upflow/backwashing configuration with entrained air to help float the finer particles leaving the heavier solids at the bottom? The finer solids can be allowed to overflow the "tank" into a trough and allowed to settle out in a nearby environmentally acceptable pond with the clarified water returned to backwash feed. A clarification aid (flocculant) may be necessary to help the fines settle out quickly

Good day sportelance...Yes !!! we considered to use that kind of tank...but we don't have it and no money to buy it.

I could be agree that it is the best idea.....we need to resolve the things with the equipment we have...if it's possible, after ask for your oppinion guys.

Good day

With all due respect

OK. Well do you have an air compressor?

If so you may still be able to utilize just air under the screening assembly to float and remove clay fines via a skimmer/overflow trough as the vibrating screen is in operation. Simple plastic underlay piping with 1/32 perforation holes to release oxygen bubbles up through screeing might be all that may be necessary to effectively liberate the clays and fines from the gravel/sand while the screen is in the water. Small upflow water supply would facilitate removal of the fines. Some concern about oxygen induced corrosion may arise. Corrosion increases as water temperature rises which I assume is not an issue.

Good day...Thank you sportelance....It is a great idea.

Nevertheless, our main concern is the potencial low settle of the material, and I think that any flow (air or water) going upward could make the situation happen.

We will make the test.

With al due respect

According to a paper http://www.ojceu.ir/main/attachments/article/18/JCEU,%20B25.pdf, washing 1 m3 of sand to remove clay / silt may increase it´s cost up to 22%. Additional processes like drying, screening, etc will increase these costs quite a bit. You will have to decide if there is a market for more expensive construction sand in your area.