1. Product Overview
Chemical Name: Sodium O-isobutyl dithiocarbonate
Abbreviation: SIBX
CAS Number: 25306-75-6
Molecular Formula: C₅H₉NaOS₂
Molecular Weight: 172.24 g/mol
Synonyms: Sodium isobutyl xanthate, SIBX collector, Sodium O-isobutyl xanthate
Sodium O-isobutyl dithiocarbonate, commonly abbreviated as SIBX, is a widely used chemical compound in the field of mineral processing, primarily functioning as a collector reagent in froth flotation. It is particularly effective in the beneficiation of sulfide ores, where it facilitates the recovery of valuable base and precious metals such as copper, lead, zinc, gold, and silver. Due to its strong collecting power, moderate selectivity, and adaptability to various flotation conditions, SIBX is among the most commonly used xanthate-type flotation reagents globally.
2. Chemical and Physical Properties
| Property | Value |
| Chemical Formula | C₅H₉NaOS₂ |
| Molecular Weight | 172.24 g/mol |
| Appearance | Pale yellow to yellowish-brown powder or granules |
| Odor | Characteristic pungent, sulfur-like odor |
| Solubility | Readily soluble in water |
| pH (1% solution) | Approx. 9–11 |
| Specific Gravity | ~1.24 g/cm³ |
| Stability | Stable under dry and alkaline conditions; decomposes in acidic environments |
| Packaging | Typically 25–50 kg drums or bags; can vary by supplier |
| Storage | Cool, dry, well-ventilated area away from moisture, acids, and oxidizers |
3. Introduction to Flotation and Collectors
Froth flotation is a critical step in the mineral beneficiation process, allowing for the separation of valuable minerals from non-valuable gangue. This process exploits differences in surface hydrophobicity between mineral particles. Collectors such as SIBX play a key role by selectively adsorbing onto the surfaces of desired mineral particles, rendering them hydrophobic. These hydrophobic particles then attach to air bubbles introduced into the flotation cell and rise to the surface, forming a froth that can be skimmed off and processed further.
4. Role and Mechanism of SIBX in Flotation
4.1 Mechanism of Action
SIBX, being a xanthate-based collector, operates through the formation of metal-xanthate complexes with metal sulfide surfaces. The process involves:
- Adsorption: SIBX molecules adsorb onto sulfide mineral surfaces through chemical bonding between the sulfur atoms in the dithiocarbonate group and metal ions (e.g., Cu²⁺, Pb²⁺, Zn²⁺) on the mineral.
- Hydrophobization: The adsorbed layer alters the surface properties, making the mineral particles hydrophobic.
- Air Bubble Attachment: The hydrophobic particles preferentially attach to rising air bubbles in the flotation cell.
- Froth Formation and Collection: The bubbles carrying the valuable minerals rise to the surface and form a froth, which is then removed for further processing.
4.2 Advantages of SIBX
SIBX is considered an efficient collector due to its:
- Strong Collecting Power: Highly effective for most sulfide minerals.
- Moderate Selectivity: Offers good selectivity in separating valuable minerals from gangue.
- Adaptability: Performs well across various pH ranges and flotation conditions.
- Compatibility: Works in conjunction with other flotation reagents, such as frothers and modifiers, to improve overall flotation performance.
- Cost-Effectiveness: Economical relative to other collector types.
5. Applications in Mineral Processing
SIBX is versatile and can be used alone or in combination with other reagents. Its most common applications include:
5.1 Copper Sulfide Ores
SIBX is widely used in the flotation of copper-bearing ores, particularly those containing chalcopyrite (CuFeS₂). It promotes high copper recoveries and improved concentrate grades. It is often used alongside dithiophosphates or thionocarbamates in complex ore bodies.
5.2 Lead and Zinc Sulfide Ores
In lead-zinc flotation, SIBX helps selectively float galena (PbS) in the lead circuit and sphalerite (ZnS) in the zinc circuit (with proper activation using copper sulfate). Its selectivity can be adjusted using depressants like cyanides or sodium metabisulfite.
5.3 Gold and Silver-Bearing Sulfides
SIBX is effective in recovering gold and silver when they occur with sulfide minerals such as pyrite, arsenopyrite, or chalcopyrite. In many gold mines, SIBX is used in combination with aerofloat reagents to boost gold recovery from refractory ores.
5.4 Nickel and PGM Ores
In flotation of nickel-copper sulfides or platinum group metal ores, SIBX acts as a base collector and is often blended with more selective reagents to balance recovery and concentrate purity.
6. Dosage and Operating Conditions
The optimal dosage of SIBX depends on the ore type, grind size, flotation circuit configuration, and presence of other reagents. General dosage guidelines are:
- Typical Range: 10–100 g/ton of ore
- pH Range: Effective in alkaline conditions (pH 7–11)
- Addition Point: Usually added at the grinding stage or at the conditioning tank before flotation
Pilot testing is always recommended to determine the most effective dosage and reagent regime for a specific ore body.
7. Comparison with Other Xanthates
| Parameter | SIBX (C₅) | PAX (C₄) | SIPX (C₅, iso) | SEX (C₂) |
| Collector Power | Strong | Moderate | Similar to SIBX | Strong |
| Selectivity | Moderate | Higher | Moderate | Low |
| Solubility | Good | Good | Good | Very High |
| Main Use | Cu, Pb, Zn, Au ores | Cu, Zn ores | Similar to SIBX | Fast-floating ores |
| Price | Moderate | Low | Moderate | Low |
SIBX offers a balanced performance, combining strong collecting ability with acceptable selectivity—making it ideal for bulk sulfide flotation or in polymetallic ore systems.
8. Handling, Storage and Safety
Handling Precautions
- Use PPE (gloves, goggles, face shield) when handling.
- Avoid inhalation, ingestion, or contact with skin or eyes.
- Ensure good ventilation in storage and processing areas.
Storage Guidelines
- Store in tightly sealed containers, in a dry, cool, well-ventilated location.
- Avoid exposure to heat, moisture, and strong acids (to prevent decomposition into toxic gases like CS₂).
Stability and Shelf Life
- SIBX is stable under alkaline and dry conditions.
- Shelf life is generally up to 12 months when stored properly.
Hazard Classification
- UN Number: 3342
- Hazard Class: 4.2 (Spontaneously combustible material)
- Packaging Group: II
- Environmentally hazardous – take care in handling effluents and tailings.
9. Environmental Considerations
While SIBX is highly effective, it can pose environmental risks if not handled properly:
- Effluent Treatment: Flotation tailings and process water containing xanthates should be treated via oxidation or biodegradation before discharge.
- Regulatory Compliance: Operations must comply with local environmental and occupational health regulations regarding xanthate use and disposal.
- Sustainability Measures: Use of biodegradable flotation reagents or closed-loop water recycling systems is encouraged where possible.
10. Conclusion
Sodium O-isobutyl dithiocarbonate (SIBX) is a vital reagent in modern mineral processing, offering a combination of strong collecting power, moderate selectivity, and broad applicability across a wide range of sulfide ores. Its effectiveness in improving flotation recovery and concentrate grades makes it indispensable in copper, lead, zinc, gold, and other sulfide ore circuits.