Chalcopyrite

Chalcopyrite is a sulfide mineral of copper and iron; it is the most common ore mineral of copper. Chalcopyrite has a chemical composition of CuFeS2 and is brassy to golden yellow in colour with an iridescent tarnish. It also yields gold and silver as a by product.

Pyrometallurgical extraction

This is a process of copper extraction from the chalcopyrite ore into pure metal.

Firstly the copper ore is crushed and ground before it is concentrated between 20-40% copper. The copper is converted to a concentration of 99% pure copper for electrochemical refining. This process involves high temperatures to first roast the copper concentrate, then it is smelted in a kiln, oxidised and the molten products have to be reduced to remove the sulfur, iron, silicon and oxygen to leave behind pure copper.

Froth flotation

Another process that can be used in the extraction of copper from its ore is a smelting process to gain crude copper. Within this procedure strong heating of chalcopyrite oxidizes the sulfide to gaseous sulfur dioxide and decreases the copper to the metal copper. The result that you receive from this procedure is

2CuFeS2(s) + 502(g) + 2 SiO2(s) 2Cu(l) + 4SO2(g) +2FeSiO3(l)

1. Concentration

After this process of smelting the copper is concentrated by a procedure of froth flotation. In this procedure the ore is crushed, ground and is mixed with a form of oil-detergent before being placed in a water bath where air is constantly forced through the substance. The copper particles float and are removed off in the foam that is produced and any unnecessary silicate particles rest at the bottom and are removed. To make the process more efficient limestone is added to raise the pH of the water bath which causes the collector to ionize and bond to chalcopyrite and avoid pyrite.

2. Roasting

The copper which is about 15% is now roasted in air which oxidizes the FeS to FeO and leaves the CuS. The chemistry that occurs within this process is

2CuFeS2(s) + 3O2(g) 2CuS(s) + 2FeO(s) + 2SO2(g)

3. Smelting

The product is then heated at 1100oC and included is ground