There are a few ways to get ice off of a gravel driveway without using salt. One way is to pour hot water over the ice. Another way is to use a shovel or pickax to chip away at the ice. A third way is to put Kitty Litter on the ice and wait for it to melt.
If you have a gravel driveway, you can try spreading some sand or ash on the ice. This will help to provide traction. You could also try using a shovel or snow blower to remove the ice.