20. In this division,
(a) “refining” means any treatment of smelter product or concentrate to remove impurities, producing very high grade metal in the metallic state;
(b) “concentration” means any treatment of ore, reject or tailing to separate a mineral substance from its gangue and obtain a concentrate;
(c) “smelting” means any treatment of an ore or concentrate wherein the charge is melted and chemically converted to produce a slag and a matte or metal in the metallic state containing impurities.