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.