use a second pan (doesn't need to be a pan, actually, just something large enough to pan and hold water).
make a sucker bottle (drugstore: hair coloring bottle, surgical tubing)
learn to do the tap, after gold is seperated, suction it up, most black sand will be gone.
add some dish soap (or Jet Dri) to the water of your safety pan to stop the ultrafine flour from floating.
pan the concentrate from your sucker bottle, then dry it and run a magnet over it. don't need to buy a fancy mag, just a rare earth one from most hardware stores, but put it in a plastic baggy over it so you don't wind up with a lot of magnetite on your mag.
or (looking over my shoulder for eco-nazis) get some merc!