Roasting black sands (aka "Shake and Bake") is a very viable way to recover some extra gold from your black sands. There are a few steps you can add to the process that will make it more effective as well as a couple of safety items to keep yourself safe while doing it.
1. Crush your sands as fine as you can get them. Somewhere in the -50 to 100 mesh size works well. The crushing process can also flatten small pieces of gold and give them more surface area which makes the easier to see in the pan.
2. Cast iron is the best type of skillet to use. It heats up quickly and will give you an even heat. Just use an oven mitt to handle the pan once its heated up.
3. Heat the sands as hot as you can but keep the temp BELOW 600 degrees. The reason you don't want to go any higher is because if there is any mercury in the sands you don't want it to vaporize. Mercury vapor is very nasty on the body and you don't want that!!!!
4. Have your quenching water as cold as you can. Floating bags of ice in it will help a lot. You don't want ice cubes floating in your water because the sands can and often will stick to them and then you have to wait for them to melt and drop the sands. The greater the difference between the temp of the sands and that of the water the more effective the process is. Eye protection while pouring the sands into the water is highly recommended. They like to go snap, crackle and pop like rice crispies on steroids.
5. For safety reasons do all this outside of course and never NEVER use a pan that you would like to cook in later! There can and often are other substances in the sands that you don't want in your body.
I often start with the sands wet because after the crushing process i Like to rinse the sand to get more of the junk out of them. If the sands are wet, put a sheet of foil over them with the shiny side down. This will keep the splatters from happening as well as help the sands to heat up faster. The shiny side will reflect heat back down into the pan while the dull side will trap heat away from the sands.
There are several threads on here that cover this subject in depth. Do a search for Shake & Bake to find them.
As a rule, I don't get into doing this process until I have a large quantity of sands built up and have nothing else to do. It is a lot of work for just a little return but it can be fun and will help pass the down time.