Refining of copper

This presentation describes all the steps included in the process to refine copper metal from its ore. All the steps are described briefly with the help of chemical equations.

1. C HEMICAL I NDUSTRIES

2. R EFINING OF C OPPER To use copper we separate it from its ore because in nature it is found as copper ores. This process of separation of copper from its ore is called Metallurgy.

3. S TEPS IN M ETALLURGY Mining of ore Crushing and grinding of ore Concentration of ore Extraction of metal Refining of metal

4. M INING OF ORE Copper ores are found underground. They are taken out by mining for further purification of ore and extraction of copper metal from copper pyrite and copper glance.

5. C RUSHING AND G RINIDING OF O RE The ores mined from the ground are mechanically crushed and ground. It is done to liberate valuable mineral (copper) from the waste (gangue) mineral .

6. C ONCENTRATION OF ORE Most copper ores contain only a small percentage of copper metal bound up within valuable ore mineral, with the remainder of the ore being unwanted rock or gangue mineral

7. C ONCENTRATION OF ORE Froth floatation: Froth floatation is used to physically separate ore from gangue. This process is used for the separation of a large range of sulphides, carbonates, and oxides for further refinement

8. E XTRACTION OF M ETAL After the separation of ore and gangue by froth flotation some chemical processes are done to extract metals. These chemical processes are roasting and smelting.

9. R OASTING Definition: The process in which minerals are converted into oxides by heating in the air below their melting point is roasting. Chemical equation: 2 CuFeS 2  + 3 O 2  → 2 FeO + 2 CuS + 2 SO 2

10. S MELTING The method to reduce metal ions to free metals is called smelting Smelting of copper ore is done in two steps i.e. formation of copper matte and bessemerization.

11. F ORMATION OF C OPPER M ATTE The roasted copper ore is heated with coke and sand at about 1100ºC. The materials melt and separate into two layers. The bottom layer that contains mixtures of Cu2S and FeS is called matte. While upper layer is called silicate slag. FeO + SiO 2  → FeO.SiO 2 2 FeS + 3 O 2  → 2 FeO + 2 SO 2

12. B ESSERMERIZATION In this process air is blown through the copper matte in the Bessemer converter. Remaining iron sulphide is oxidized and removed as slag. In the final smelting step cuprous sulphide is oxidized to form cuprous oxide, which react with remaining cuprous sulphide to form metallic copper. Cu2S+O2→2Cu+SO2

13. R EFINING OF M ETAL The metal obtained from smelting contains impurities, that can be refined by electro refining or distillation.

14. An electrolytic cell is used in electro refining, in which impure metal act as anode and a sample of pure metal acts as cathode. At the  anode : Cu (s)  → Cu 2+ ( aq )  + 2e − At the  cathode : Cu 2+ ( aq )  + 2e −  → Cu (s)