Materials Crushing Processes: Limestone, Granite, and Basalt

Crushing is a fundamental process in mining, construction, and aggregate production. Different materials require specialized crushing techniques to achieve optimal particle size, shape, and efficiency. This article explores the best practices for crushing limestone, granite, and basalt, including equipment selection, process optimization, and industry applications.

Limestone Crushing: Soft but Abrasive

Characteristics:

• Medium hardness (Mohs 3–4) but can be abrasive due to silica content.
• Used in cement production, road base, and agricultural lime.

Recommended Crushing Process

1. Primary Crushing:

• Equipment: Jaw crusher or impact crusher.
• Output Size: 150–300 mm.
• Why? Jaw crushers provide high reduction ratios, while impact crushers are better for softer limestone with lower abrasiveness.

2. Secondary Crushing:

• Equipment: Cone crusher or hammer crusher.
• Output Size: 20–50 mm (for construction aggregates).

3. Tertiary Crushing (Fine Grinding):

• Equipment: Vertical shaft impactor (VSI) or roller mill.
• Output Size: <5 mm (for cement raw meal or powder applications).

Key Consideration:

Limestone tends to generate dust, so wet crushing or dust suppression systems are recommended.

Granite Crushing: Hard and Durable

Characteristics:

• Extremely hard (Mohs 6–7), high compressive strength (200–300 MPa).
• Used in high-quality concrete, railway ballast, and decorative stone.

Recommended Crushing Process

1. Primary Crushing:

• Equipment: Heavy-duty jaw crusher (for high compressive strength).
• Output Size: 200–400 mm.

2. Secondary Crushing:

• Equipment: Cone crusher (multi-cylinder hydraulic type for better particle shape).
• Output Size: 20–40 mm (ideal for asphalt or concrete).

3. Tertiary Crushing (Sand Making):

• Equipment: VSI crusher (for high-quality manufactured sand).
• Output Size: 0–5 mm (for premium concrete mixes).

Key Consideration:

Granite is highly abrasive, so high-manganese steel wear parts are essential for crushers.

Basalt Crushing: Tough and Dense

Characteristics:

• High density (2.8–3.0 g/cm³), tough (Mohs 5–6).
• Used in railway aggregates, asphalt, and erosion-resistant construction.

Recommended Crushing Process

1. Primary Crushing:

• Equipment: Jaw crusher or gyratory crusher (for high-capacity operations).
• Output Size: 150–350 mm.

2. Secondary Crushing:

• Equipment: Impact crusher (for better cubical shape) or cone crusher (for high reduction ratio).
• Output Size: 10–30 mm (ideal for road base).

3. Tertiary Crushing (Fine Aggregates):

• Equipment: VSI crusher (for high-quality sand) or high-pressure grinding rolls (HPGR).
• Output Size: 0–10 mm (for high-strength concrete).

Key Consideration:

Basalt produces sharp-edged particles, so impact crushers are preferred for better shape control.

Industry Trends in Crushing Technology

• Smart Crushing: IoT sensors for real-time monitoring of wear and performance.
• Energy Efficiency: Variable frequency drives (VFDs) reduce power consumption by 15–20%.
• Dust Control: Advanced suppression systems meet environmental regulations.
• Mobile Crushers: Increasing demand for portable crushing plants in remote mining sites.

Efficient crushing of limestone, granite, and basalt requires tailored approaches based on material hardness, abrasiveness, and end-use requirements. By selecting the right jaw, cone, impact, or VSI crushers, operators can maximize productivity while minimizing wear and energy costs.