A smelting furnace can be used to melt down all types of metals, including aluminium, brass and bronze. This could be useful if you want to recycle metals and create your own tools, cans or anything else. A smelting furnace can be made of firebrick and metal canisters with a heat source connected to it.
Locate a large clay or metal canister to use as the outer lining of the smelting furnace. Drill a hole to allow your propane or gas nipple through the canister. If you are using two gas elements, drill two holes.
Layer the can with ganister, which is like cement and is made of crushed firebrick and mortar. Lay down two relatively small firebricks inside the canister as a foundation so they are just below the drill holes and allow plenty of room for the gas fired flame to heat the canister.
Build a cylindrical inner lining from sheet metal. Simply form it into a tube that is as wide in diameter as you would like the inside of the furnace to be. Drill matching holes for the ones in the outer canister at the bottom. They will be about 1 inch from the bottom of the cylinder in most cases.
Slide the cylinder into place and thread a piece of pipe through all the holes, connecting all the pieces together.
Fill this form with ganister or clay, pushing it into place and then let it all dry overnight. The following day, remove the form and pipe. Let the form cure for several days.
Enlarge the holes in the form to fit your gas burners, and then install the burners to complete your smelting furnace.
This is a simplified version of a smelting furnace; more complex smelters will have multiple controls to adjust the heat levels. You can use an iron pot inside this furnace to melt down metals. The gas burners provide the heat, and the liner provides the insulation to contain and magnify the heat.