Copper can be found in it's element form however, it is usually mined from its ores, such as chalcopyrite or chalcocite or bornite.

Question

Copper ore/Chalcopyrite is treated through the following processes to extract pure copper(99.8%Cu).
1. Pulverization
2. Concentration/ froth floatation
3. Roasting
4. Smelting
5. Besemerisation
6. Electro refining
Explain each extraction process and insert equations where necessary

Answer 1

1. Pulverization:
The first step in the extraction process is pulverizing the copper ore into small particles. This increases the surface area of the ore and makes it easier to separate the copper minerals from the gangue (unwanted rock and minerals).

2. Concentration/Froth Floatation:
The pulverized ore is then mixed with water and chemicals, including frothers and collectors. Frothers help to create a stable foam on the surface of the pulp, while collectors selectively bind to the copper minerals. Air is then blown through the mixture, causing the copper minerals to attach to the air bubbles and float to the surface as a froth. This froth, containing the copper minerals, is skimmed off and collected.

3. Roasting:
The froth obtained from the froth floatation process is subjected to roasting. Roasting involves heating the ore in the presence of excess air or oxygen. This step helps to remove any impurities present in the copper concentrate and convert certain metal sulfides in the ore into oxides. The reactions involved in roasting depend on the specific composition of the copper ore but usually involve the conversion of copper sulfide minerals into copper oxide and sulfur dioxide gas:

2CuFeS2(s) + 3O2(g) -> 2CuO(s) + 2FeO(s) + 2SO2(g)

4. Smelting:
The roasted copper concentrate is mixed with a reducing agent, such as coke (carbon), and heated in a furnace. This process, called smelting, aims to reduce the copper oxides back to metallic copper while removing impurities present in the concentrate. The carbon in the coke reacts with oxygen present in the copper oxides, resulting in the production of carbon dioxide gas and the reduction of copper oxide to metallic copper:

2CuO(s) + C(s) -> 2Cu(s) + CO2(g)

5. Bessemerisation:
The smelted copper metal obtained from the furnace is subjected to a process called bessemerisation, where it is purified further. The molten copper is blown with air or oxygen, which oxidizes any remaining impurities, such as iron and sulfur, that might be present in the metal. The impurities are selectively oxidized and can be removed as slag, leaving behind pure copper metal.

6. Electrorefining:
The final step in the extraction process is electrorefining, where the purified copper obtained from bessemerisation is further purified electrolytically. The impure copper metal is used as the anode, and a pure copper cathode is used. The anode and cathode are placed in an electrolyte solution containing copper sulfate. When an electric current is passed through the electrolyte, copper ions from the anode are oxidized and dissolve in the electrolyte, while copper ions from the electrolyte are reduced and deposited onto the cathode as pure copper. This process ensures that the final copper product is 99.8% pure.