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-   -   Got Grit? (http://talk.craftweb.com/showthread.php?t=11996)

art reed 06-03-2018 08:15 PM

Got Grit?
 
I have several hundred pounds of used silicon carbide grit.
Has any one ever seen or built some kind of washer/reclaimer?
Thanx,
Art

Greg Vriethoff 06-03-2018 10:44 PM

Grit is broken down as it is used. You'd have to sift it manually with screens to get proper sizes. Then you still have to deal with how to separate the raw material from the swarf (i.e. glass particles) of what you have been grinding with it.

Sounds like a lot of trouble for any return. Is it possible? Maybe. But is it worth it? I say no. My two cents.

Pete VanderLaan 06-04-2018 06:00 AM

I just bought 100 lbs of recycled 120 mesh grit and it is absolutely as nice as brand new stuff. It only ran one dollar a lb as opposed to up to four bucks a lb for pristine. I'm using it in the rougher and the sandblaster.

The rougher is always harder on grit and does not do as good a job of separating the fines out. We have a cascade system in the slurry buckets that allows the coarse grain to be reclaimed. The blaster does do that far better using a large filter.

At this point I'm bagging up my old crap and it goes to the landfill. It's too messy to screw with.

art reed 06-04-2018 08:07 PM

I remember when Steuben was up and running each mill had a kind of articulated sluice that let the grit settle out and carried of the lighter weight glass particles.
I agree, It is messy, and takes a lot of time. I was just wondering if someone had come up with an easy solution.
I hadn't thought about using it in the sand blaster...
Thanks guys.

Art

Pete VanderLaan 06-05-2018 06:49 AM

I think trying it in the sandblaster after the fact of having all those fines will just clog the blaster filters Art.

Our separation method has the machine with a set of hoses surrounding the grinding wheel head so that grit coming off the wheel is slurried away to a drain which dumps into three buckets, each with a slot punched in the side. The heavy stuff stays in the first bucket, the second by dead weight gets the next grade and the final is really just silicate and ultra fines. There's a pump at the bottom of the big bucket, and that bucket hold about 30 gallons of water constantly recycling back to the grit tray for the wheel as well as to those hoses around the wheel. If you grind a lot the grit buckets should be cleaned daily, dumping the contents on the actual grinding wheel at the sessions end to let it dry somewhat over night. The big bottom bucket gets cleaned about once every three months and is like a sedimentary deposit requiring drill and blast.

It is a dirty job but doing the buckets each day is important. Now that I have this new recycled nice grit, I'm just throwing out all those old fines. I don't want to breath it at all and I don't want it settling on other tooling.

Peter Bowles 06-11-2018 06:36 PM

The thing you are looking for is an Elutriator.
In its most simple form its a container with a water feed to the bottom with variable and measurable water flow. The mixed grit goes in, the water gets set to a value, and the less dense material gets carried away over the top to a second container. Different water flows will float different size particles over the rim. That's the theory.
I've read on a couple of lapidary sites this done with greater of lesser degree of success, but those old boys have different tolerances to us and they do like to eek every morsel out of anything they have to purchase.
You would never really know what particle size you were getting, so perhaps only useful for separating away the larger unused grit.

Pete VanderLaan 06-12-2018 11:28 AM

I love the name "Elutriator. "

think of panning for gold. Peter describes the process well. The only stuff you will really want to keep is the coarse stuff. The stuff coated with silicates gets really slippery. I suppose in gold you just turn needy.

Interestingly, Schott Optical or Steuben ( I forget which) at one point was doing blood tests on employees who were grinding lead glasses. The testing revealed elevated lead levels in those employees. I don't know whether that was from breathing the mist around the machines or from skin absorption.
All the big grinders from Steuben went to the dump and were never put up for sale because of lead concerns.

Joe Pfeifer 07-01-2018 12:52 PM

There might be a local lapidary that could use this stuff in their tumbler?


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