Smelting by-product is a term used to describe the materials that are produced as a result of smelting, which is the process of heating ore to extract a base metal. The three main smelting by-products are speiss (6 letters), SLAG (4 letters) and dross (5 letters). Speiss is a form of matte that is created during the smelting process and is composed of iron, nickel, copper and sulfur. SLAG is a glassy material that is created when impurities are removed from the ore during smelting. It is composed of calcium, magnesium, silicon and aluminum. Dross is a mixture of metal oxides and other impurities that are left over after smelting. It is composed of zinc, lead, copper and other metals.