Full Pathway: CuFeS2 → Pure Cu

Ore: Chalcopyrite / Copper pyrite (CuFeS2)

Step 1 — Concentration: Froth flotation (CuFeS2 is hydrophobic sulphide)

Step 2 — Roasting to Matte: $2CuFeS_2 + O_2 \rightarrow Cu_2S + 2FeS + SO_2$ Matte = Cu2S + FeS (liquid sulphide mixture)

Step 3 — Smelting (Fe removal): $2FeS + 3O_2 \rightarrow 2FeO + 2SO_2$ $FeO + SiO_2 \rightarrow FeSiO_3 \downarrow \quad \text{(slag, removed)}$ After this: only Cu2S remains in the Bessemer converter

Step 4 — Self-Reduction in Bessemer Converter: $2Cu_2S + 3O_2 \rightarrow 2Cu_2O + 2SO_2 \quad \text{(Step 4a)}$ $Cu_2S + 2Cu_2O \rightarrow 6Cu + SO_2 \quad \text{(Step 4b, self-reduction)}$ Product: Blister copper (~98% pure, blistered by escaping SO2)

Step 5 — Electrolytic Refining:

• Anode: Impure blister copper
• Cathode: Pure copper sheet
• Electrolyte: Aqueous CuSO4 (acidified)
• Anode mud: Au, Ag (less electropositive, don't dissolve)
• More electropositive impurities (Fe, Zn, Ni): dissolve but don't deposit

Product: Pure copper (>99.99%)

Bessemer Converter Diagram