Instructables explains that aluminum cans can be melted using a propane torch. A steel drum or a canister is needed to act as a crucible, which should be insulated and stabilized by sand. For maximum safety, all the work should be done outside on a flat, fire-retardant surface.
Before starting the project, it is necessary to check for all the tools and materials needed, which include safety goggles, fire-retardant welding gloves, pliers (or alternative safe tool for lifting the hot crucible), a cupcake tin, a safe canister for residue and a steel ladle.
Start by crushing the cans, making them as compact as possible. Add a crushed can to the crucible, and place the torch over it until it melts. Once the first can has melted, further cans can be added to the crucible. Additional cans will melt quicker, as the molten aluminum adds to the heat created by the torch. A residue will form on top of the molten metal; this is the paint and other coating elements from the cans. Use a ladle to remove it, and place it somewhere safe to cool.
When finished melting all the cans, lift the crucible, and pour the liquid aluminum into the cupcake tin. Once cool, the resulting aluminum blocks, or ingots, should be easy to remove and can be used for metal working projects.