graphite ore processing

Graphite ore processing involves several steps to extract and purify graphite from raw ore. The specific methods depend on the type of graphite (flake, amorphous, or vein) and its associated impurities. Below is a general outline of the graphite ore processing flow:

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1. Crushing & Screening
– Primary Crushing: Large chunks of graphite ore are crushed using jaw crushers or gyratory crushers.
– Secondary Crushing: Further reduction in size using cone crushers or impact crushers.
– Screening: The crushed material is screened to separate fine and coarse particles.

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2. Grinding (Milling)
– The crushed ore is ground into a fine powder in ball mills or rod mills to liberate graphite flakes from the gangue (waste rock).
– Overgrinding should be avoided to prevent damaging graphite flakes.

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3. Beneficiation (Concentration)
The goal is to separate graphite from impurities like quartz, mica, pyrite, and clay. Common methods include:

# A. Flotation (Most Common for Flake Graphite)
– Conditioning: The slurry is mixed with reagents (frothers like pine oil, collectors like kerosene/fuel oil).
– Froth Flotation: Air bubbles attach to hydrophobic graphite particles, floating them to the surface while hydrophilic impurities sink.
– Multiple Stages: Rougher flotation → Scavenger flotation → Cleaner flotation to improve purity.

# B. Gravity Separation (For Coarse Flakes)
– Uses jigs, shaking tables, or spirals to separate graphite based on density differences.
– Less effective for fine graphite but useful as a pre-concentration step.

# C. Magnetic Separation
– Removes magnetic impurities (e.g., iron oxides) using low-intensity or high-intensity magnetic separators.

# D. Acid/Alkali Leaching (Chemical Purification)
– Used for high-purity applications (e.g., battery-grade graphite).
– Hydrofluoric acid (HF), sodium hydroxide (NaOH), or hydrochloric acid (HCl) dissolve silicate and metal impurities.
– Requires careful handling due to environmental and safety concerns.

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4. Dewatering & Drying
– The concentrated graphite slurry is dewatered using thickeners, filters (vacuum or pressure), or centrifuges.
– Dried in rotary dryers or fluidized bed dryers to reduce moisture content (<1%).

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5. Classification