From Mine to Concentrate: Stibnite Processing Explained

aerial view of the ore processing plant

Stibnite (Sb₂S₃) is the primary mineral source of antimony, a critical element used in flame retardants, batteries, alloys, semiconductors, and chemical industries. As high-grade antimony deposits become scarce, efficient stibnite processing has become essential to maximize recovery and produce high-quality antimony concentrates.

This article explains the complete stibnite processing journey—from mine to concentrate, covering mining, crushing, beneficiation, and concentrate handling in a clear, step-by-step manner.

Understanding Stibnite and Its Importance

Stibnite is a sulfide mineral of antimony characterized by its high density, metallic luster, and relatively low hardness. It is commonly associated with quartz, calcite, pyrite, and other sulfide minerals.

Why Stibnite Processing Matters:

Stibnite is the main commercial source of antimony

Antimony demand is rising across multiple industries

Efficient processing improves recovery and reduces operating costs

Understanding stibnite's mineralogical properties is key to designing an effective processing flow.

The stibnite processing cycle begins with ore extraction, typically through open-pit or underground mining depending on deposit depth and structure.

Key Mining Considerations:

Ore grade and vein thickness

Rock hardness and fragmentation

Dilution control to maintain feed quality

After mining, the run-of-mine (ROM) ore is transported to the processing plant for further treatment.

Crushing reduces large ore fragments into smaller particles suitable for grinding and beneficiation.

Common Crushing Equipment:

Jaw crushers (primary crushing)

Cone or impact crushers (secondary crushing)

Controlled crushing is important because stibnite is relatively soft and brittle; excessive crushing can produce fines that negatively impact recovery.

After crushing, the ore undergoes grinding and classification to liberate stibnite crystals from gangue minerals.

Typical Equipment:

Ball mills or rod mills

Hydrocyclones or classifiers

Proper grinding fineness is critical. Under-grinding leads to poor liberation, while over-grinding creates slime losses during flotation.

Two-Stage Closed Ciruit Grinding System

Due to its high specific gravity, gravity separation is often used as a pre-concentration step in stibnite processing.

Common Gravity Separation Methods:

Jigging

Shaking tables

Spiral concentrators

Gravity separation removes coarse gangue early, reducing the load on flotation circuits and improving overall efficiency.

Froth flotation is the most widely used method for producing high-grade antimony concentrates from stibnite ores.

Flotation Process Overview:

Collectors selectively bind to stibnite particles

Frothers create stable air bubbles

Depressants suppress unwanted sulfide and silicate minerals

Common Flotation Reagents:

Xanthates and dithiophosphates (collectors)

Pine oil or MIBC (frothers)

Lime, sodium silicate, or starch (modifiers)

Flotation allows precise control over concentrate grade and recovery.

After flotation, the antimony concentrate contains excess water and must be thickened and dewatered.

Dewatering Equipment:

Thickeners

Vacuum filters

Filter presses

The final drying stage reduces moisture content, making the concentrate suitable for smelting or export.

Responsible tailings management is a critical component of modern stibnite processing plants.

Environmental Measures Include:

Tailings thickening and safe disposal

Water recycling systems

Dust and emissions control

Monitoring antimony levels in wastewater

Sustainable practices help meet regulatory requirements and reduce environmental impact.

Stibnite processing presents several technical challenges, including:

Fine-grained mineral dissemination

Sensitivity to over-grinding

Complex ore compositions with multiple sulfides

Advanced process control and reagent optimization are often required to overcome these challenges.

The journey from mine to concentrate in stibnite processing involves a carefully coordinated series of steps, including mining, crushing, grinding, gravity separation, flotation, and dewatering. Each stage plays a crucial role in producing high-quality antimony concentrate with maximum recovery.

By understanding stibnite's mineral characteristics and applying the right processing technologies, mining operations can improve efficiency, reduce costs, and meet the growing global demand for antimony.