Abstract: A process for the preparation of carbon fibers, including the steps of:subjecting a raw material oil to thermal cracking conditions at a temperature of between 400.degree. to 500.degree. C. while removing cracked, light hydrocarbon components to obtain a pitch product containing at least 5 weight % of mesophase and not more than 10 weight % of light hydrocarbon components with a boiling point at 60 mmHg (absolute) of 300.degree. C. or less and having a softening point of between 140.degree. and 220.degree. C., the raw material oil having a boiling point of at least 500.degree. C. and containing at least 30 weight % of a residual oil which has a boiling point of at least 500.degree. C. and a metal content of at least 200 weight ppm and which is derived from a napthene base and/or intermediate base petroleum crude;removing the mesophase having a particle size of more than 10 .mu.

Abstract: A process for producing carbon fiber is disclosed, which comprises a preoxidation step for heating precursor fibers in an oxidizing atmosphere and converting them into partially oxidized fibers, an oxidizing step for heating the partially oxidized fibers in an oxidizing atmosphere and converting them into oxidized fibers, and a carbonization step for heating the oxidized fibers in an inert atmosphere and converting them into carbonized fibers, in which in the preoxidation step the precursor fibers are heated at a temperature of about 200.degree. to 250.degree. C. and in which a portion or the whole of the exhaust gas from the oxidation step is supplied into the preoxidation step as the oxidation atmosphere gas and the exhaust gas from the preoxidation step is subjected to a burning treatment.

Abstract: A method for treating the fine-grained spend absorbent (primarily calcium sulfite and calcium sulfate) from a dry flue gas desulfurization process. The absorbent, having a small amount of binder therein, is oxidized in a fluidized bed reactor at a temperature in the range from about 700.degree. C. to about 1000.degree. C. to produce a dry essentially fully oxidized pelletized calcium sulfate product.Calcium sulfate pellets having an average diameter of from about 0.5 mm to 5 mm and containing from about 1% to about 3%, by weight, of binder constituents, are composed of agglomerated calcium sulfate particles having an average diameter of from about 50.mu. to about 100.mu. bound to each other by the binder constituents.

Abstract: Zeolite A containing sodium and potassium ions, otherwise known as 3 .ANG. molecular sieve, may be prepared by a direct route when the aqueous aluminosilicate reaction mixture to be aged at elevated temperatures contains a mole ratio of Na.sub.2 O to Na.sub.2 O and K.sub.2 O which is greater by a factor of about 1.1 than the mole ratio of Na.sub.2 O to Na.sub.2 O and K.sub.2 O in the zeolite A product. Preferably, the reaction mixture also contains zeolitic nucleation seeds to promote crystallization of the product.