| abstract |
[PROBLEMS] To prevent damage to a furnace due to solidification of a transition metal as an impurity when heat-treating carbon fibers, and to reduce Fe, C Provided are a method for reducing the content of metals such as o and Ni, an apparatus therefor, and the carbon fiber. An inert gas flowing into a furnace contains vaporized metal impurities, and gas is removed from a high temperature portion of the furnace. The impurities in the extracted gas are cooled and solidified and recovered, and the remaining gas is reused as an inert gas again in the furnace. |