How to Filter Sea Water

I doubt whether it would be practical. If it's sand you're dredging, say about 1mm dia., it will settle and drain pretty freely. If some of the finer stuff overflows and you have to do a bit more dredging than if you caught it all, I would guess that's easier and cheaper than trying to filter the overflow.

Cheers...........Codey

There are any number of ways.

• One could spin the material so as to increase the separation force.
• One could allow the material to settle longer, so as to increase the separation.
• One could fit a collector-strainer in the bottom of the collection vessel, and pump the strained water back overboard.
• etc.

A cyclone is sometimes used in sand plants to seperate sand from water.

You don't need to go to too fine a particle size, so pressure drop isn't too bad

Not knowing what the sand is being used for I would say that it would be washed before use. All the fine silt that is now going over board would be removed in the wash. Most of these operation are along water ways so it just ends up back in the river beds. If your dredging to clear a water way. Then get the bulk of the bottom up is all you should worry about. Around here that is done with shovel not pumps to keep the fine silt from being stirred up. So why worry about it. But if you want to collect it a bigger barge or a slower pump would help.

this dredge needs to be designed so it uses the bed of sand as a sand bed filter. This will get the grits and the fines(slimes) If there are too much slimes it might block the filter.

when you reach your dumping place you can drop the load through the bottom via clamshell opens, as long as you have flotation. with this method you will be able to dump very clear water. the clearer you want it the larger the flat area of the bed = the whole barge. beds like this are often formed with fine gravel, then sand and in municipal water plants, they back wash it to get rid of the fine grits and slimes. If you dump, you lose the whole bed and will have to reform it over a screen first . It needs design work.

its been done

http://www.google.ca/search?hl=en&q=barge+%2B%22sand+filtration%22&btnG=Google+Search&meta=&aq=f&oq=

Dear Sir,

Normal sand carrying barges (wherein either electric or hydraulic under water pumps deliver the material to the barge above ) have large bins on deck ( therefore above water line ). The watertight tight decks of the barge(s) form the bottom of the bins which have steel bulwarks to contain the dredged sand. Your barge can probably be modified (subject to stability) in a similar and simple : configuration.

These bins have outlets for the sea-water usually with fine wire to retain the small particles of sand . This in turn allows the surplus water ( simply by : gravity ) to drain before the barge is towed back to the discharge point . Probably why Del the Cat , humorously, suggested to you to drill holes in the bottom of the barge !

If the above simple answer does not help you I suggest you use Del the Cat as Consultant.

Labor Omnia Vincit.

Some good some bad answers. The biggest challenge with a dredger is to get the design of the hoppers such that the settling time is as short as possible, this increases dredging capacity.

By the way the poster that had the heavy stuff above deck and drains the water out the bottom has got is wrong. Keep the heavy stuff low down and let the water overflow from the top.

I have not seen filters to prevent the loss of the sand that has not settled, with the kind of volumes that these things pump I would think this is probably not practical, but then what do I know?

Put horizontal wells and pumps on the floor of the barge. Put geofabriic on the well tudes to keep sand out and pump away to remove water from the material. Start with 50% removal before any determination to move it up. Go full cycle with the engineering and be sure you can uload the barge safely.

Increase vessel's height; when you reach the upper edge, you'll still have part sand part water overflow, but overall eficiency over a period of time will be increased.

Yahlasit

Guest,

If you can cover the vessel top using a plain nylon or polyester gauge say 60 to 200 mesh number, it should be workable for an upward flow. It could give good flow for water as well severing effect to sand. Rinsing is also so easy. You got to tie the fabric surface to the vessel top or use round frames if possible. Based on permeability you may use single double layer gauges. No much cost is involved. Try that.

thanks a tonn every one , from all the suggestions it is clear that sea water has to be filtered, and some have already suggested some filtering medium.... i request you to plz let me know where are these materials available or plz suggest me some source...

Guest,

Nylon / polyester bolting clothes will be normally available from textile screen material dealing trading shops. These gauge fabrics are actually being used for flat screen making and filtering purposes. They are permeable to water and not for partcles depending upon mesh[no of holes per linerar inch]. Nylon is extensible and polyester is fairly rigid. Take trial and fix up. I also recommend a tiltable fiter frame to be kept on the mouthof your vessel to enhance close/ open operations conveniently. Report if you make trials. Regards.

I believe Hydroclones (centrifuges based on water flow) are used for separation of water from coal in many coal washeries. Another alternative might be to use what is called a Dutch State Sieve Bend which is a screening operation which utilizes a vertcal drop of solids containg ores/coal on an appropriately sizes screen to filter water from the solids. Wet screening of ores and coals is a well defined technology, but likely expensive for your uses.