Backstop cleanout

[knotbrush]

Imagine 22,000 lbs of ground-up tires with all the steel and other stuff removed, ground to @ 1/8" pebbles. This is the material in the backstop of a club's shooting range. There is a conservative estimate of 10,000 lbs of lead and to a much lesser degree copper, in the rubber. This isn't the first clean-out/rebuild, the last one was five years ago. The idea is to remove all the material, separate it and reuse the rubber. One of the ideas we've had is to float the rubber in water and skim it off. But, 1/2 of a sample amount floats, 1/3 sinks and 1/6 stays suspended. I doubt there is much lead in the material above the target line. The sample was taken at the very bottom, about 5' below the target line. They don't really want the range down for more than a week to do the clean-out and replace the front which is 4' wide x 3/4" thick conveyor belt lengths suspended from the ceiling and anchored to the floor and overlap by 8" and screwed together. The conveyor belting is bulging out close to a foot in the center of each of the ten lanes. It seems that this type of backstop is excellent for stopping bullets and keeping the dust to a minimum.

If we could find some body that would just take it all away for the lead value, that would be ideal.

I did try a sample in a saturated saltwater solution with no difference. Out of 1/2 of a 5 gal. pail of material, I harvested 8-1/2 lbs of lead but it took about 2-1/2 hours of screening with 1/4" hardware cloth and "panning" the rest of the rubber out. And, there is a lot of lead that went through the screen. I'll test for BHN tomorrow. Any ideas?

I didn't post this, you guys don't know who I am, it's purely hypothetical, 33,000 lbs. of toxic waste doesn't really exist. BUT, I sure hope to get my hands on some of that non-existent HYPOTHETICAL lead! I wonder what the BHN will be? I "imagine" there would be a LOT of .22s in there.

[dodgyrog]

Doesn't the lead migrate to the bottom of the pile of rubber? If so remove the top layer and take out the lead rich lower 10% and burn it - somewhere a long way from habitation. That should yield CO2, Carbon, Dross and a lot of lead.
That's the best I can think of.

[milkman]

Time might be the limiting factor, but putting a bucket full of material on a simple vibrator should let all the lead migrate to the bottom.

A half horse motor rigged to an eccentric should be easy to put together.

[unclebill]

Time might be the limiting factor, but putting a bucket full of material on a simple vibrator should let all the lead migrate to the bottom.

A half horse motor rigged to an eccentric should be easy to put together.

+1
i keep thinking some kind of shaker table.
no water

[dodgyrog]

Same as is used in a foundry to get the casting sand away.

[lavenatti]

You could give compressed air a try to blow off all the lighter material. You won't have all that contaminated water when you're done too.

It won't matter that some of the rubber sinks, it's still not as heavy as lead.

[gray wolf]

compressed air would create a lot of lead dust.
This sounds like a job for a large company with the proper equipment.
I would try what I could and be happy with what I got.
A shaker table or some type of hydrological ( sluice ) would get the job done.

[steve in kc]

stock tank filled with a brine solution (water + water softener salt or some other form of salt) not sure of the salinity you would need, but it will make all the rubber float to the top and lead to drop to the bottom. Skim the rubber, leave the lead behind and shovel it out later into smaller managable pails.

[scrapcan]

I think I would try the liquid of a different density that will allow the lead to sink and the rubber to float. Try something that is soluble with water as the clean up will be much easier.

Or you can call one of the range builders that use crumb rubber for the backstop to see what they reccomend. Caswell might be a plac eto start.

Barring that you might see if you can volunteer some tiem to the contractor that gets hired in exchange for some of the recovered product.

[Harter66]

I get a couple of dump trailers fill them level take them for a drive , I do live in a land of 10,000 miles of washboard roads though. Shovel the top 2/3s off or back into a cleared trap area. Then about every other or maybe 3rd load water skim the rubber . Lotta manual labor but for even 5tons in a week worth it.

[RP]

Remove as much as you can as easy as you can then put the rest back in the range no one says it all has to be removed.

[runfiverun]

what don't float on the salt water will most definately float on top of melted lead.
you can take the salinity up to 20% and lead will still sink through it.

[knotbrush]

what don't float on the salt water will most definately float on top of melted lead.
you can take the salinity up to 20% and lead will still sink through it.

Great idea! But...I tried a saturated salt solution and nothing changed. I found that quite puzzling! Maybe some other chemical might work. One problem is that we have events and different programs going on 5 or 6 days a week and none of the participants want the range down for very long. I did talk to an abatement company and they started talking about sealed drums and hasmat disposal. OUCH!!! I hope to find a company that would just remove the material for the lead! We'll probably have to sweeten the deal.

[beagle]

Interesting thread. I've been watching the series on Gold Mining Alaska which is down to the final show this week and looking at the trials and tribulations they've encountered.

A $250K operation and they're handling boulders as big as refrigerators down to about 50 feet but they're also recovering dust gold.

I've thought several times during this process what it would be like to run a backstop through their rig and recover everything.

Financially impractical but it would be nice.

I'd love to have a rig on a modified lawnmower that would handle small amounts of range dirt. I'm sure someone out there has thought of this so something may come up.

Still, it's nice to dream./beagle

[runfiverun]

if you run a rocker box wet it's a mini version of thier set-up.
a recirc pump and classifier screens with a spraybar you gotta rock it your self a little bit but it's been around for a while.
they actually upsized the idea.
and you could build your own rockerbox from wood, the riffles won't be as good and you'd lose some of the fines over them, but it'd be very effective.
easy to build, and all youd need is some plywood and some 1x2's a recirc pump,or a garden hose
a few plastic pipe fittings and a driveway.
then it'd be shovel/shake, shovel/shake.

[dverna]

Very similar situation at an indoor range I used to shoot at.

A guy came up with a shaker table and a fan with a set of air nozzles to blow off the rubber and paper. It worked very well but I would recommend canister masks and disposable coveralls.

Don Verna