To remove impurities from copper scrap, melt the metal scrap over a stove until it liquefies completely. Using a metal spoon, remove the impurities from the surface of the melted metal. Take adequate safety precautions - including protective clothing, safety goggles and welding gloves - when melting the metal.
Use a heavy-duty pot made of cast iron to melt the copper scrap. Cut the scrap into small pieces, and put them in the pot until it is half full. Avoid filling the pot completely with the metal scrap pieces because a pot filled with molten metal is unsafe to work with.
Attach a pair of vice grips on the side of the pot opposite its handle. These grips are useful for holding or lifting the heavy pot safely with both hands. Next, place the pot with the scrap metal pieces on the stove grate. A camp stove that runs on propane or a barbecue grill with a side burner is suitable.
Ensure that the stove grate can support the pot's weight. If not, place a heavy-duty grate over the existing one. Allow the metal to melt fully. Skim off the impurities that float on the melted metal's surface, and discard them in another metal bucket.