I picked 100 lbs of reclaimed shot. Not thrilled. It is full of dust and junk. Aside from being a general mess it is clogging up the loader. Any ideas as to how I might efficiently clean it?

I understand adding some graphite powder might be advisable but Im not sure about the dosage or a source for graphite. I have some graphite powder sold as a friction reducing additive for epoxy (West System 423, left over from a boat building project). Think I should add some?

Thanks in advance.