Answer: Leaching (dissolve metal) → Purification/Separation (SX/IX) → Reduction (electrolysis or cementation).
- A Leaching (dissolve metal) → Purification/Separation (SX/IX) → Reduction (electrolysis or cementation)
- B Roasting → Smelting → Refining, the classic pyrometallurgical sequence instead according to conventional understanding
- C Ore crushing → Froth flotation → Smelting, a concentration-then-pyrometallurgy sequence in routine practice
- D Direct reduction → Casting, skipping any aqueous dissolution step largely overall in most cases
Correct answer: A. Leaching (dissolve metal) → Purification/Separation (SX/IX) → Reduction (electrolysis or cementation)
Explanation: Hydrometallurgy sequence: selective dissolution of metal into solution (leaching) → separation from impurities (solvent extraction, ion exchange) → recovery of pure metal (electrowinning or chemical reduction).
An Ellingham diagram plots ΔG° of oxide formation against temperature for different metals; whichever line is LOWER (more negative ΔG°) at a given temperature reduces the oxide of any metal whose line sits above it - the basis of carbon reduction (Fe, Zn) vs electrolytic reduction (Al, Mg, Na) decisions.
Concept context
The science of extracting metals from ores and refining them for use. Covers concentration methods, reduction techniques, refining processes, and the thermodynamic principles that govern metal extraction.