I have run a small mineal Jig, they are used for sorting by specific gravity or weight of paticals. jigging involves alot of water and that attracts the EPA.
Here is a picture of a small Jig http://graymfg.com/mineral.html
when in operation you can put your fingers on the screen and it feals like a calf sucking on your fingers.
In our aplication the gold ended up on the screen and in the bottom of the unit. For coal I understand you need to put mushroom like structures on the screen that allow the rocks to go out a pipe in the side of the unit, that is a option these pictures don't have, and I have never seen.
Sizing coal is a whole different and simpler project. Probably the easiest way is to get some top soil proccessor to screen it for you, he will want money, they might want winter work.
Maybe get one of these for that bobcat that loads your trailer
everybody loves bobcats.
I sorta like the bucket tromel http://www.youtube.com/watch?v=Kt7rj02sLhA
these come from other manufactures for loader backhoes. How about diping it in a pond to get rid of fines.
Caution I love spending other peoples money.