The beneficiation of antimony ore by flotation is a widely used method to concentrate antimony minerals from their ores, particularly stibnite (Sb₂S₃), which is the most common antimony-bearing mineral. Below is a detailed overview of the process:
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1. Ore Preparation
– Crushing & Grinding: The antimony ore is first crushed and ground to liberate the stibnite particles from the gangue (waste material). The optimal particle size for flotation is typically in the range of 100–200 mesh (74–149 μm).
– Desliming: Fine slimes (clay or ultrafine particles) may be removed to improve flotation efficiency.
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2. Flotation Process
Flotation exploits differences in surface hydrophobicity between stibnite and gangue minerals. Key steps include:
# A. Reagent Conditioning
– Collectors:
– Common collectors for stibnite include xanthates (e.g., potassium amyl xanthate, PAX) or dithiophosphates.
– In some cases, lead nitrate (Pb(NO₃)₂) is added to activate stibnite surfaces.
– Frothers: Pine oil, MIBC (methyl isobutyl carbinol), or other frothers stabilize bubbles.
– Depressants:
– Gangue minerals (e.g., quartz, carbonates) may be depressed using sodium silicate or starch.
– If pyrite is present, lime (CaO) can depress it at high pH (~9–11).
– pH Modifiers:
– Slightly alkaline conditions (pH ~6–9) are often optimal for stibnite flotation.
# B. Flotation Circuit
– Rougher Flotation: Initial separation to produce a low-grade Sb concentrate.
– Scavenger Flotation: Recovers residual Sb from tailings.
– Cleaner Flotation: Upgrades rougher concentrate by removing impurities through multiple stages.
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3. Concentrate Treatment
– The final concentrate typically contains 45–60% Sb, depending on ore grade and process efficiency.
– Further processing may involve:
– S.jpg)
ting to produce antimony metal or oxide.
– Leaching for high-purity applications.
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4. Challenges & Considerations
– Fine Particle Losses: Ultra-fine stibnite may report to tailings;