Abstract: A reactor vessel is provided having a solids feed opening for particulate graphite and a product outlet for purified particulate graphite. The vessel has an interior volume for containing the graphite particles, with a plurality of gas feed openings at the bottom of the interior volume, near the centre-line, for feeding of chlorine-containing gas, wherein the chlorine-containing gas passes through the particulate graphite, fluidizing the particulate graphite. Electrodes are provided which function to heat the particulate graphite, as it is carried upwards under the fluidizing effect of the centrally injected chlorine-containing gas. When the heated graphite particles react with the chlorine gas, purified particulate graphite is formed and may be extracted through the product outlet.