The Comprehensive Guide to Crushing and Sand-Making in the Aggregates Industry
The global construction and infrastructure sectors rely heavily on high-quality aggregates, including crushed stone, sand, and gravel. As urbanization accelerates, demand for processed mineral resources—particularly micaceous iron oxide (MIO) and other industrial minerals—has surged. Crushing and sand-making technologies play a pivotal role in transforming raw ore into market-ready materials with precise particle sizes and gradations.
1. Primary Crushing:
– Jaw crushers or gyratory crushers reduce large ore blocks (e.g., micaceous iron oxide) to ~150–300 mm. Hard, abrasive ores like MIO require wear-resistant manganese steel liners.
– Key Consideration: Pre-screening (e.g., vibrating grizzly feeders) removes fines to optimize throughput.
2. Secondary/Tertiary Crushing:
– Cone crushers or impact crushers further refine material to 20–50 mm. For micaceous ores, multi-stage crushing minimizes overgrinding and preserves lamellar structures.
3. Sand-Making Stage:
– Vertical shaft impactors (VSIs) or roller crushers produce 0–5 mm manufactured sand (M-sand). Micaceous iron oxide’s flaky morphology demands adjustable rotor speeds to control particle shape.
– Innovation: Dry sand-making systems reduce water usage, critical for arid regions.
4. Screening & Grading:
– High-frequency screens classify particles by size. MIO’s density (4–5 g/cm³) may require specialized screening decks to prevent blinding.
1. How to mitigate wear in MIO processing?
Use ceramic-lined chutes and tungsten carbide tips for crushers. Regular maintenance intervals are critical.
2. Can dry sand-making meet environmental standards?
Yes, with pulse-jet dust collectors and enclosed conveyors, emissions can stay below 20 mg/m³.
3. Optimal moisture content for screening MIO?
Keep below 3% to prevent adhesion; heated screens may be necessary in humid climates.
Project: A Brazilian MIO processing plant upgraded its circuit to produce paint-grade powder (200 mesh).
– Primary: CJ612 jaw crusher → Secondary: HP300 cone crusher → Tertiary: B9100 VSI for shaping → Ball mill for ultrafine grinding.
By integrating advanced equipment selection and process optimization, producers can unlock higher profitability while meeting stringent quality benchmarks across industries—from construction to specialty chemicals.
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