초록 ▼

A process employing a fixed-resin bed Acid Retardation Unit (ARU) to separate spent acid from chlorine dioxide generators into a de-acidified sodium sulfate component and a purified sulfuric acid component. The de-acidified sodium sulfate produced is returned to the chemical recovery cycle of the kr

A process employing a fixed-resin bed Acid Retardation Unit (ARU) to separate spent acid from chlorine dioxide generators into a de-acidified sodium sulfate component and a purified sulfuric acid component. The de-acidified sodium sulfate produced is returned to the chemical recovery cycle of the kraft mill in place of acidic chlorine dioxide generator effluent thereby avoiding the destruction of alkalinity in pulp mill liquors. In addition, sulfuric acid is purified providing an opportunity for reuse in various mill applications, and/or concentrated and recycled to the generator. Alternatively, to avoid high evaporation costs, the purified acid can be used to regenerate a cation-exchange unit (CEU) used in the conversion of sodium chlorate to a sodium chlorate/chloric acid mixture which is fed to the generator in place of sodium chlorate and sulfuric acid. Using this approach, the sulfuric acid requirement of chlorine dioxide generators and, in turn, the amount of acidic generator effluent can be reduced. The process is applicable to both atmospheric and subatmospheric chlorine dioxide generators. In the latter case, the concentration of the purified sulfuric acid from the ARU or any other acid separation system can be increased by using a portion of it to dissolve the sodium sesquisulfate by-product from such generators.

대표청구항 ▼

[ We claim:] [1.] In a process for the treatment of a chlorine dioxide generator effluent from a chlorine dioxide generator selected from the group consisting of atmospheric generators and sub-atmospheric generators, which effluent contains sulfuric acid and sodium sulfate so as to recover a deacidi

[ We claim:] [1.] In a process for the treatment of a chlorine dioxide generator effluent from a chlorine dioxide generator selected from the group consisting of atmospheric generators and sub-atmospheric generators, which effluent contains sulfuric acid and sodium sulfate so as to recover a deacidified sodium sulfate solution and a purified sulfuric acid solution, wherein the improvement comprises:a. feeding the effluent containing sulfuric acid and sodium sulfate to a fixed-resin bed acid retardation unit incorporating a particulate quaternary ammonium resin wherein the acid is sorbed by the resin and sodium sulfate is rejected to produce a deacidified sodium sulfate solution and recovering said deacidified solution; andb. eluting acid sorbed in said acid retardation unit with water, to recover a purified sulfuric acid solution.