JNTU B.Tech III Year NONFERROUS EXTRACTIVE METALLURGY Previous Question Paper (November/December - 2018 - R13)

The important ores of copper are primarily classified into sulfides, oxides, and carbonates. The most significant ores include:

• Chalcopyrite (CuFeS₂): The most abundant and economically important copper ore.
• Chalcocite (Cu₂S): A high-grade copper sulfide ore.
• Bornite (Cu₅FeS₄): Often referred to as peacock ore due to its iridescent tarnish.
• Malachite (CuCO₃·Cu(OH)₂) and Azurite (2CuCO₃·Cu(OH)₂): Important carbonate ores found in the oxidized zones of deposits.
• Cuprite (Cu₂O): An important oxide ore.

The electrolysis of sulphide mattes, commonly known as the Hybinette process or similar electrolytic refining techniques, is primarily used for the recovery of metals like nickel from copper-nickel mattes. In this process, the cast sulphide matte serves as the soluble anode in an electrolytic cell.

During electrolysis, the base metals in the matte dissolve into the electrolyte. By carefully controlling the cell potential and electrolyte composition, specific metals are selectively deposited at the cathode while impurities and precious metals report to the anode slime. This method is particularly effective for separating nickel from copper and precious metals, as the sulphide anode allows for the direct electrochemical oxidation of the metal content without the need for prior conversion to pure metal, thereby reducing processing stages.