Purification of natural amorphous graphite by flushing process

Amorphous graphite slurries used in flushing operations were conditioned at pH4.2 in the presence of chelating and reducing agents both to release gra phite and clayey particles and to enhance the hydrophobicity of the graphit e surface, Graphite particles were first extracted from the aqueous slurry using a kerosene-based oil phase, while clayey impurities (including kaolin ite, illite, chlorite and quartz) were left in the water phase, Then, the r esidual clayey impurities in the graphite particles mere extracted from the oil phase using an aqueous solution containing the same reagents as used f or making the raw slurries, The ash content of purified products proportion ally decreased with increasing amount of dissolved iron component, indicati ng the existence of iron (III) hydro.uide compounds which aggregate the con stituent particles of raw graphite, Furthermore, the efficiency of removing the impurities became greater as the particle size of the pulverized raw g raphite decreased because of the improvement in liberation of clayey impuri ties from graphite particles. In a graphite sample with a mean particle siz e of 2 mu m, the ash content could be lowered from 8.4 to 2.8 mass%.