Leaching in the Flotation Process Flow
Leaching is a hydrometallurgical process used to extract metals from ores by dissolving them in a suitable solvent (e.g., acids, alkalis, or cyanide). When integrated into the flotation process flow, leaching can enhance metal recovery, especially for complex or refractory ores. Below is an overview of how leaching fits into flotation circuits:
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1. Role of Leaching in Flotation
– Pre-Flotation Leaching: Used to remove soluble impurities or oxidize refractory minerals (e.g., gold locked in sulfides) before flotation.
– Post-Flotation Leaching: Applied to flotation concentrates (e.g., copper, nickel, or gold concentrates) to further extract metals.
– Alternative to Flotation: For some ores (e.g., oxide copper or gold ores), leaching may replace flotation entirely.
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2. Typical Process Flow with Leaching
# Option 1: Pre-Flotation Leaching
1. Ore Preparation: Crushing/grinding to liberate minerals.
2. Leaching Stage:
– Ore is treated with a lixiviant (e.g., sulfuric acid for copper oxides, cyanide for gold).
– Soluble metals dissolve, leaving behind gangue/flotation-compatible sulfides.
3. Solid-Liquid Separation:
– Pregnant leach solution (PLS) sent to metal recovery (e.g., electrowinning, precipitation).
– Residual solids proceed to flotation for sulfide recovery.
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# Option 2: Post-Flotation Leaching
1. Flotation First: Produces a concentrate rich in target minerals (e.g., pyrite for gold, chalcopyrite for copper).
2. Leaching of Concentrate:
– Concentrate is reground (if needed) and leached under aggressive conditions (e.g., pressure oxidation for refractory gold).
3. Metal Recovery: PLS is processed via adsorption (carbon), solvent extraction, or electrowinning.
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3. Key Considerations
– Ore Type: Oxide ores often leach directly; sulfides may require oxidation (bioleaching/acid pressure leaching).
– Reagent Compatibility: Ensure flotation reagents don’t interfere with leaching kinetics.
– Tailings Management: Neutralize acidic