Abstract: An improved high yield apparatus for producing sodium hydrosulfite is disclosed wherein sodium borohydride, sulfur dioxide, sodium hydroxide and sodium bisulfite are reacted. Improved results are obtained according to the invention by a novel feed system that requires the introduction of a first reaction mixture comprising sodium borohydride, sodium hydroxide and water (i.e., BOROL) into a process flow stream upstream from, i.e. prior to, the introduction of a second reaction comprising either (1) water and sulfur dioxide (first embodiment) or (2) sodium bisulfite and sulfur dioxide (second embodiment).The best results are realized by combining the just described novel feed arrangement with a system where intimate mixing of both the first reaction mixture and the seocnd reaction mixture and the flow stream.

Abstract: An improved high yield process and apparatus for producing sodium hydrosulfite by reacting sodium borohydride, sulfur dioxide, sodium hydroxide, and sodium bisulfite is provided. The improved result of the invention is obtained by a feed system that requires the introduction of a first mixture comprising sodium borohydride, sodium hydroxide, and water into a flow stream prior to the introduction of a second mixture comprising water and sulfur dioxide. The improved result can be further enhanced by techniques of intimately mixing the first mixture and the flow stream as well as intimate mixing the second mixture and the flow stream.