Abstract: Disclosed herein are a process for producing a carbon fiber mat, having excellent production and energy efficiencies, comprising successively melt-spinning a fiber-forming pitch by a centrifugal spinning machine having a horizontal axis of rotation (parallel to the plane on which the spinning machine is placed), forming a mat by the thus spun pitch fibers, bringing the mat into an infusibilized state in an air atmosphere containing NO.sub.2 and calcining the thus infusibilized mat in an inert atmosphere, and an apparatus for carrying out the above-mentioned process.

Abstract: The present invention relates to a method for preparing carbon fibers from a pitch by melt-spinning the pitch, infusibilizing the pitch fibers with a mixture of air and a gaseous oxidizing agent in an infusibilizing furnace divided into at least two chambers arranged in series under the condition of a velocity of the circulation gas in a specified range and then carbonizing the thus treated pitch fibers into carbon fibers.

Abstract: The present invention relates to a method for preparing carbon fibers from a pitch by treating the pitch fibers spun from a pitch with a gaseous mixture of air and a gaseous oxidizing agent in an infusibilizing furnace divided into at least two chambers arranged in series and then carbonizing the thus treated pitch fibers into carbon fibers.

Abstract: A method of producing carbon fiber by making infusible and carbonizing pitch fiber which is obtained by melt-spinning petroleum-tar pitch or coal-tar pitch, and a method of making pitch fiber infusible in an air atmosphere containing NO.sub.2, at an elevated temperature by introducing a cross-sectionally U-shaped tray with pitch fiber suspended from bars placed across an upper portion thereof into an infusible material producing furnace having gas exchanging chambers in the inlet portion and outlet portion thereof as well as at least two gas circulating means each of which comprises a combination of a blower or a fan and a heat exchanger, and retaining said tray in said furnace.

Abstract: A method of producing carbon fiber by making infusible and carbonizing pitch fiber which is obtained by melt-spinning petroleum-tar pitch or coal-tar pitch, and a method of making pitch fiber infusible in an air atmosphere containing NO.sub.2, at an elevated temperature by introducing a cross-sectionally U-shaped tray with pitch fiber suspended from bars placed across an upper portion thereof into an infusible material producing furnace having gas exchanging chambers in the inlet portion and outlet portion thereof as well as at least two gas circulating means each of which comprises a combination of a blower or a fan and a heat exchanger, and retaining said tray in said furnace.

Abstract: A sulfur dioxide-containing exhaust gas is scrubbed by contact with an aqueous solution containing an alkali salt of an organic acid to dissolve sulfur dioxide in the aqueous solution in the form of alkali sulfite. The alkali sulfite in the solution is converted by oxidation into alkali sulfate, which is contacted for reaction with a calcium compound to form calcium sulfate. The calcium sulfate so formed is separated by filtration from the aqueous solution for recovery while the filtrate is recycled for use as the aqueous solution for scrubbing the exhaust gas. The concentration of alkali sulfite in the scrubbing aqueous solution is maintained at a level of less than 1% to ensure efficient removal of sulfur dioxide from the exhaust gas in the form of calcium sulfate.