METHOD FOR MANUFACTURING CONCENTRATED SULFURIC ACID

摘要

PROBLEM TO BE SOLVED: To provide a method for manufacturing low-cost and stable concentrated sulfuric acid with which a sulfuric acid purity content in the concentrated sulfuric acid after removal of dissolved sulfur dioxide in a removing tower is always maintained at a specification value or higher irrespective of seasonal variation or change in weather and corrosion of equipment surrounding an absorption tower or lowering of capacity of the absorption tower do not take place. SOLUTION: In removing the sulfur dioxide dissolved in the concentrated sulfuric acid in the removing tower, the concentrated sulfuric acid is brought into contact with a plant exhaust gas having <=0.1% moisture content and the dissolved sulfur dioxide is made to migrate into the plant exhaust gas and is removed. As the plant exhaust gas, an outlet gas from the absorption tower containing <=3,000 ppm sulfur dioxide concentration at the absorption tower of the concentrated sulfuric acid manufacturing plant or gaseous nitrogen exhausted from a cryogenic oxygen plant annexed to a nonferrous metal refinery can be used.