Abstract: The invention relates to a process for preparing prilled bisphenol A by granulation which comprises adding compounds soluble in molten bisphenol A, not affecting adversely the melt color of bisphenol A to any significant extent, and have a melting point of 60.degree. C. or more to bisphenol A and granulating and also to a process which comprises adding the reaction mother liquor or cyrstallization mother liquor produced in the manufacturing step of bisphenol A to bisphenol A or the adduct of bispheol A and phenol or a mixture of bispheol A and phenol, removing the phenol, and granulating. The processes yield prilled bispheol A which have high strength and resist powdering.

Abstract: This invention relates to a process for preparing bisphenol A of good heat stability by heat-treating bisphenol A containing a very small amount of impurities in a molten state at 185.degree. to 220.degree. C. for 5 to 60 minutes in an oxygen-free atmosphere and the process yields bisphenol A of good heat stability which shows reduced coloration when heated. Bisphenol A prepared by this process has excellent properties relating to color and is particularly suitable as raw material for the manufacture of polycarbonates where the requirement for color is strict.

Abstract: This invention is directed to a heat recovery type combustion apparatus which has a regeverative member of ceramic material attached to the lateral wall of the main body of the combustion apparatus, a rotary duct set in place and adapted to communicate with the regeverative member, an air conduit for allowing flow of combustion air and an exhaust gas conduit for allowing flow of exhaust gas arising from combustion of fuel in the combustion apparatus both formed in the interior of the rotary duct, and rotary means adapted to rotate the rotary duct and enable the combustion air to be heated with the exhaust gas through the medium of the regeverative member.