The copper ore is crushed, ground and then enriched (concentrated) by Froth Flotation. The powdered ore is mixed with a special paraffin oil which makes the copper mineral particles water repellent. It is then fed into a bath of water containing a foaming agent which produces a kind of bubble bath.
When jets of air are forced up through the bath, the water repellent copper mineral particles are picked up by the bubbles of foam. They float to the surface making a froth. The unwanted waste rock (gangue) falls to the bottom and is removed.
The froth is skimmed off the surface and the enriched ore (mainly the copper mineral) is taken away for roasting. The mixture of water, foaming agent and paraffin is recycled. After this stage the enriched ore now contains about 25% copper by mass.
Later, roasting and smelting stages should be done. During the roasting stage, the chemical reactions begin. They convert the copper minerals into copper metal, and then the smelting process begins.
The calcine is heated to over 1200 °C with fluxes such as silica and limestone. The calcine melts and reacts with the fluxes. Some impurities form a slag which floats on the surface of the liquid (like oil on water) and is easily removed. Until now, the flow chart of copper smelting is finished. Of course, copper investors can adjust the flowchart according to the grade of copper ore.