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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. This is achieved by the use of a dual compartmented cylindrical motionless mixer wherein the input means for the first reaction mixture is located at a distance upstream from the first compartment of the mixer that is about the same as the diameter of the mixer and the second reactant mixture input means is similarly located at a distance upstream from the second compartment that is also about the same as the diameter of the mixer. Improved results are also obtained by using the dual compartmented cylindrical mixer above described in conjunction with the known reactant feed systems involving embodiments (1) and (2) above described, i.e. where the reactant inputs are reversed.

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First Claim