Melting copper in a forge is a relatively simple, straightforward foundry process. Copper's melting point is 1,984 degrees Fahrenheit, which is relatively low compared to steel or other heavy metals. The most efficient method for melting copper, especially high purity plumbing and wiring scrap, is in a self-contained forge. This is a ceramic kiln base inside a closed forge. The fuel, in the case of copper, can be varied, based on its low melting point. However, pure charcoal with a forced air input -- at 2,800 degrees Fahrenheit -- works best for a home-based smelting operation.
Things You'll Need
- Scrap copper
- Ceramic closed crucible
- Spray-on rubber molding release agent
- Replicast 101 liquid rubber
- Ceramic silica casting powder and activator
- Lawnmower shroud
- 140-amp stick welder
- 2-inch steel pipe
- Concrete and perlite
- Concrete or firebrick forge
- Hardwood charcoal
- 2-inch to 1 1/2-inch steel reduction connector
- Acetylene torch
- Plugged 2-inch steel flange pipe
- 1 1/2-inch shop vac hose
- Duct tape
- 110-volt hair dryer
- Casting tongs
- Full body casting suit
- Welder's gloves
- Welder's face mask
- Ingot or billet molds
Place the scrap copper to be melted into a covered ceramic crucible and place the cover on it. (If a ceramic crucible is not available, one can be cast by making a liquid rubber casting, pressing two 10-inch diameter glass bowls, sprayed with a release agent, together with the rubber between them and holding it until it sets. Then remove the inside bowl and fill it with a ceramic/activator paste, forming it up the sides to create a vessel. Allow it to set for 24 hours then cure it at 2,500 degrees Fahrenheit in a commercial kiln or forge.)
Place the covered crucible in the center of the forge on elevated pedestal. If no pedestal is available, stack firebricks into a square arrangement with space over the center hole in the forge. If a forge is not available, make one using a steel lawnmower shroud, welding a 2-inch pipe into its center hole and filling it with a 50/50 mix of high sand-content concrete and perlite.
Cover the crucible and the circular area around it for 12 inches, with a 10-inch-high stack of high-quality charcoal.
Attach a 2-inch to 1 1/2-inch steel reduction connector to the outside end of the plugged steel flange pipe. (If a plugged steel flange pipe is not part of the forge, make one by capping the male threaded end of a piece of 2-inch steel pipe, 2-feet longer than the diameter of the forge, and welding a slip to female-threaded connector to the other end. Then, cut a 1 1/2-inch upper, center hole in the top of the pipe, at a point that will allow it to be inserted into the center of the forge with the hole facing upward.) Insert the reduced steel flange pipe into the forge.
Attach a 1 1/2-inch shop vac hose to the open end of the steel flange pipe. Use duct tape to connect the hair dryer to the other end of the shop vac hose and turn it on low speed.
Spray the charcoal with charcoal lighter and light the forge.
Monitor the forge flame and when it gets to a cherry red color, turn up the airflow on the hair dryer to full or high speed.
Wait until the forge center, near the crucible, is white hot and check the time. Wait for 90 minutes and allow the crucible interior temperature to max out, melting the copper.
Turn off the hair dryer and scrape any charcoal off the top of the crucible and away from its outside edges, exposing the cylinder for grasping. Use smelting tongs and or forge calipers and lift the crucible out of the forge, placing it on the ground or concrete surface.
Remove the crucible lid and pour the ingots.
Tips & Warnings
- Experiment with the amount of copper that is optimum for a smelting operation in the crucible you have.
- Use extreme caution when working with molten metal. Wear a full-body casting suit, welders gloves and face mask.
- "Metal Casting: A Sand-Casting Manual for the Small Foundry - Vol.1"; Stephen D Chastain; 2004
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