The nitric acid concentration plant includes two production lines, Line-1 (280 TPD) and Line-2 (320 TPD), which concentrate 68% nitric acid into 99% product nitric acid. The lines are two independent stand-alone process lines. Line-1 concentrates nitric acid 68% to nitric acid 99% using sulfuric acid 96% as an extraction medium. In the upper part of the extraction column, nitric acid is rectified to 99% and removed from the top. From the bottom of the extraction column, diluted sulfuric acid 75% is removed. Line-2 also concentrates 68% to 99% but uses sulfuric acid 85% as an extraction medium. The diluted sulfuric acid 75% is concentrated to 85% using steam. The concentrated 99% nitric acid from Line-1 & 2 are sent to bleaching tower, where impurities are removed using air as stripping gas. All the off-gases from both the lines are washed together in off-gas treatment section.