Purification of natural amorphous graphite using an oscillating liquid-liquid continuous extraction apparatus

Through a flushing process, natural amorphous graphite was highly purified using a commercial oscillating liquid-liquid continuous-extraction apparatus. Aqueous slurries of raw graphite with a mean particle size of 2 mu m were conditioned at pH 4.2 in the presence of chelating and reducing reagents, and the graphite particles were extracted using a kerosene-based oil phase. The graphite particles in the oil phase were returned to an aqueous dispersion with the addition of a nonionic surfactant and sodium carbonate, and were recovered by centrifugation. The ash in the graphite decreased from 16 to 2 mass% as a result of the separation of clapey impurities. The excellent functionality of the extractor for refining amorphous graphite was attributed especially to its perforated cylinder-shaped impeller capable of inducing a high shearing stress. Not only are fine oil droplets created, which are favorable for the collection of graphite particles, but the aggregates of raw graphite are also released as individual particles.