Task: Touch of Refinement! Coming up at the end of this section.

		Smelting and refining consist of extracting the desired chemical elements from the ore concentrate. After these primary processing operations, the market value of the chemical elements usually doubles!
	Source

4.1.1 Impurities

When taken out of the concentrator, the copper ore concentrate may contain 20 to 50% copper. However, the average is around 25%.

The rest of the concentrate is made of undesirable substances, mainly minerals from the ore gangue, but also chemical elements other than copper, which are in the ore itself.

These undesirable substances are called impurities or "slag." Two industrial processes are employed to remove the slag: hydrometallurgy, which uses chemicals, and pyrometallurgy, which uses heat.

Pyrometallurgy is used on copper ore. It is a three-step process (roasting, smelting and converting) and is carried out in a plant called a "smelter."

A final process, refining, completes purification. It is done in a plant called a "refinery."

		Horne smelter, Rouyn-Noranda, Québec.
	Source