Abstract: This invention provides a process for producing a free hydroxylamine aqueous solution, by letting an alkali react with separated sulfates, for conversion into ammonia and sulfates not containing any nitrogen atom, recovering the valuable ammonia and recycling it in the reaction system for effective use. This invention is a process for producing a free hydroxylamine aqueous solution, in which a free hydroxylamine aqueous solution is obtained by letting an aqueous solution or slurry containing hydroxylammonium sulfate and a gas mainly containing ammonia react with each other, mixing a solution mainly containing a lower alcohol with the produced aqueous solution or slurry, and separating the precipitated sulfates containing ammonium sulfate, comprising the steps of mixing an alkali with the separated sulfates, to produce ammonia gas, and recycling the ammonia in the reaction system.

Abstract: The invention provides: an aggregate comprising a core made of an elastic material and a surfacing material adhered thereon by use of a resin; a manufacturing process of the novel aggregate comprising such steps as mixing 100 parts by weight of a core made of an elastic material with 0.1 to 20 parts by weight of a resin to cause the resin to stick uniformly on the surface of the core, and thereafter, contacting and mixing the core with 1 or more part by weight of a surfacing material having one-tenth or less average particle diameter of that of the core; and a resin mortar mixing the novel aggregate, a resin and preferably other additives.

Abstract: The present invention provides an efficient dimethyl sulfoxide (DMSO) production process improved in the conversion from dimethyl sulfide (DMS) to DMSO by recycling the NOx used as a catalyst in the continuous oxidation reaction of DMS for producing DMSO, specifically providing a DMSO production process improved in the recovery rate and/or absorption rate of NOx by recovering NOx from the reaction off gas and/or the gas removed from the reaction product solution for re-utilization.