Abstract: Residual impurity reduction methods and apparatus are provided. A method comprises conducting a gaseous stream through an unlined portion of a pipe, wherein the gaseous stream comprises sodium and wherein the unlined portion of the pipe is at least about eighteen inches long, injecting a neutralizing agent into the gaseous stream at an injection point, wherein the injection point is located at a point where the sodium is in at least a partially condensed state. The gaseous stream is conducted through a heated portion of a pipe and a cooled portion of a pipe. In addition, methods and apparatus may include a trap system for use with a carbonization furnace.

Abstract: Residual impurity reduction methods and apparatus are provided. A method comprises conducting a gaseous stream through an unlined portion of a pipe, wherein the gaseous stream comprises sodium and wherein the unlined portion of the pipe is at least about eighteen inches long, injecting a neutralizing agent into the gaseous stream at an injection point, wherein the injection point is located at a point where the sodium is in at least a partially condensed state. The gaseous stream is conducted through a heated portion of a pipe and a cooled portion of a pipe. In addition, methods and apparatus may include a trap system for use with a carbonization furnace.

Abstract: Hydrogen cyanide removal during transformation of a carbon fiber precursor into carbon fiber is provided. The method may comprise heating a carbon fiber body precursor at a substantially atmospheric pressure to above about 1200° C. in a furnace in a first stage, expelling a stream of effluent gas outside the furnace, wherein the stream of effluent gas comprises a cyanide, thermally oxidizing the cyanide during the first stage, and heating the carbon fiber body precursor to a temperature of between about 1600° C. and about 2200° C. in a second stage.