Which Antimony Process Maximizes Stibnite Recovery from Complex Sulfides?

Bruno

Chief Mineral Processing Engineer

+8613402000314

2026-02-12

The recovery of antimony from complex sulfides, particularly stibnite (Sb₂S₃), requires carefully designed processes to maximize yield due to its association with other sulfide minerals. Depending on the mineralogical characteristics, geochemistry, and complexity of the ore, several processes may be employed. Among them, the hydrometallurgical process and pyrometallurgical techniques are widely used, and flotation methods are often employed as a preparatory step. Here are the key processes to maximize stibnite recovery:

1. Selective Froth Flotation Process

• Purpose: Flotation is typically the first step to concentrate stibnite from complex ores containing sulfides of other metals like lead, zinc, or iron. This method leverages the surface properties of antimony sulfide to separate it efficiently.
• Reagents: Collectors such as xanthates (potassium ethyl xanthate) or dithiophosphates are commonly used. Depressants, like lime or water glass, are essential to suppress unwanted sulfides.
• Optimization: Adjusting pH to between 5 and 7 maximizes selectivity for stibnite compared to other sulfide minerals.

2. Pyrometallurgical Extraction

• Method: Roasting of stibnite followed by reduction is a traditional method for antimony extraction. The stibnite is initially roasted in air to produce antimony trioxide (Sb₂O₃) while sulfur is removed as SO₂. Antimony trioxide is then reduced to antimony metal using carbon or a suitable reducing agent.
• Advantages: Effective for high-grade ores and can handle stibnite directly without intensive ore preparation steps.
• Challenges: Produces sulfur dioxide emissions, which need to be managed carefully. Also requires significant energy input.

3. Hydrometallurgical Process

• Method: A common hydrometallurgical route involves leaching stibnite. Popular leaching agents include alkaline solutions (sodium hydroxide or sodium sulfide) or acidic solutions (such as hydrochloric acid).
  • Sodium sulfide solution dissolves antimony sulfides to form soluble antimonates, which can then be precipitated as antimony trioxide or metallic antimony.
  • Hydrochloric acid leaching can also dissolve stibnite with subsequent electrodeposition for antimony extraction.
• Advantages: More environmentally friendly than pyrometallurgy, especially for complex ores containing arsenic or other impurities.
• Challenges: Requires careful process control of leaching conditions (temperature, concentration, etc.). Impurities like arsenic need to be removed during downstream processing.

4. Combined Approach

For complex sulfide ores containing multiple metals, strategic combinations of flotation, hydrometallurgy, and pyrometallurgy can be applied to maximize antimony recovery. Sequential processing isolates stibnite selectively while addressing difficulties posed by impurities.

Summary:

• Flotation is critical for concentrating stibnite efficiently, especially in complex ores.
• Hydrometallurgical processes (alkaline or acidic leaching) are increasingly preferred due to environmental considerations and scalability.
• Pyrometallurgy remains useful for high-grade stibnite ores but faces declining usage due to ecological concerns.

For maximizing antimony recovery, a testwork program tailored to the specifics of the ore should be conducted to determine the optimal combination of these processes. Advances in beneficiation and green chemistry also continue to improve recovery rates.

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