Mixed with water to form a slurry, the minerals are concentrated, initially, in a sophisticated flotation process. By passing air through the slurry, the minerals adhere to the air bubbles and float to the surface. The froth is scraped off and dried leaving a concentrate which is refined further to make the final pure metal products. The zinc is then recovered by electrolysis which separates the zinc from the solution. The final lead product is then collected from the base of the blast furnace.
Copper concentrate is refined by a slightly more complicated process.
The concentrate is roasted and then smelted in a furnace producing a slag containing waste and metal of high quality called copper matte. The slag is removed. Copper matte is processed further in a converter where air is blown through the molten metal to burn off sulphur. A second slag forms to collect any remaining impurities. Finally, the metal is refined to 99.9 percent purity through electrolysis.