Blasting medium seperator

[Piero]

Hi guys

Needa bit of thought and input please

I will start with what I own/have then say what I am truing to achive


I have to hand a large free standing blasting cabinet, two large air compressors to supply the air (total 22 fad)
A basting pressuertised pot which I fill with steel grit.
also to hand a rather large twin motor twin stage fillter extractor (look more like a massive hover, old shcool)

What I am tying to do is build a system that seperates the very fine dust that I dont want to re-use and and have a system were the larger grit get collected for re-use.

I dont want a hand on anything, the simpler the better

Have been looking at building my self a cyclone ,this will fit in line from the bottom of the blasting cabinet and before the filter/hover extractor that I have


my only worries is getting the seperation right.
I am worried that if the extractor fillters get a little cloged, the air voloserty will be reducd and then the seperation ratio gets messed up etc etc

would a simple wire mesh of a few microns at the base of the blast cabinet be more simple and more relierble????

 

[rtbcomp]

I built a mechanical sieve.

I use it with a coarse mesh to get the big bits of rubbish out and then with a fine mesh (60 holes per inch) to remove the dust.

 

[500e]

http://www.jpthien.com/smf/
I know its for wood But lots of info on cyclone's

 

[Piero]

I have a sieve built into the funnel of the blast pot, it takes out any big bits.

what I dont want is the very fine, worn out grit flying around creating dust inside the cabinet.

 

[ben8vgte]

Our clemco at work has a seperator on top of the pressure pot, all it is a large curved plate that allows all the larger stuff to fall down. It takes a while to set it up so it does not pick everything up, then it goes into a filter pack that drops all the waste into a hopper.

I can grab a few pics tommorrow if it helps, as I know my explanition is not great.

edit.. This one http://www.hodgeclemco.co.uk/wp-content/themes/Hodge Clemco/images/photos/Cabinet-DSCF3749.png

 

[Piero]

very interesting

Am I right in saying the pot is NOT presserised????

I can see how it re cycles it and filters it, seems to be using a cyclone and dropping the medium into the pot for re-use. but the pot can be presseriused???

 

[ben8vgte]

Yeah the pot is pressurised, it has a sprung loaded valve in the top. So when you lift of the pedal and the pressure drops all the media falls back into the pot, while you are blasting it just collects in the hopper above.

In that picture you cant see the extractor fan and filter setup, though the filter is there to stop it kicking out dust into the atmosphere.

 

[Piero]

ahh ok

does the cyclone part of it remove the fine dust well??? or does the fine stuff end up staying in with the heavy grit???

 

[ben8vgte]

It's not a cyclone really, just a curved downwards plate. The angle of the plate and amount of suction sets what partical size is drawn off into the filter pack and waste bin. Really it's just gravity that seperates the media.

We use a fairly fine garnet so it's set to quite a low suction, with a heavy shot type media it could be set much higher. For us it does not remove all the fine stuff each time round, but as above its just as we use a fine media.

Some pics will make much more clear, I think it would be quite simple to make really. Even if you just collected it into a pot and tipped it into your pressure pot. Rather than have a valve in the pot for example, the Clemco guy who came and installed did say the setup does work better with heavy iron shot generally and will take out more fine stuff each pass.

 

[Piero]

Thanks
but dont trouble your self with photos, really.

now you have explained it, its a system I know.

I build a large collection pot under my own blast cabinet with a Y peice conecting tube from the cabinet to the pot.

my extractor was conected to the Y peice with a mesh filter stuck in the Y peice exit pipe.

the fine stuff went up the Y peice and ended in the collection sack of my exctractor,
the corser grit that was to larg to go up the Y piece filter just fell into the collection pot

was simple and worked well.

am just fishing for ways to inprove it really

 

[normspanners]

I designed a dust extraction plant from a cyclone the cyclone was 3mtrs dia and 6mtrs high with a 30 hp fan a little larger than your blast cabinet! , but it worked on a vacuum system with the fan at the end,blowing onto a rubber sheet above a water tank the bottom of rubber sheet was touching the water at rest as the air flow increased it moved the sheet further but the air and dust was blasted at the surface of the water, the dust then carried on into the water and sank to the bottom, the tank then could be washed out periodically the idea was the tank end automatically adjusted to adapt to the amount of air allowed into the system without any cloth bag filters to block

 

[Piero]

Sounds good.

Only I am using metal grit.

Rust would be an issue lol

 

[c-k]

may as well ask on this one instead of making new one, what sieves are people using ? i mainly use 30-60 mesh and need to sieve out the rubbish thats starting to block the end of gun from blast pot and extraction is only doing half the job of fine dust

 

[rtbcomp]

I sieve with 30 mesh and occasionally use 60 mesh to remove dust. I use crushed glass and even the finest stuff has a sharp edge.

I rely on the extractor to get rid of the dust, but if I've had to blast a lot of filler then I sieve the dust out.

The biggest problem dust causes is that it stops the media dropping down the pot, instead a hole forms through the media and I have to depressurise the pot to cause the body of media to collapse.