Used 70 TPD Nitric Acid Concentration Plant built in 2005. The plant contains two process sections: nitric acid concentration and sulfuric acid concentration. The NAC takes fresh nitric acid and recycled acid mixtures (55% - 69%) to generate concentrated nitric acid up to 99.4% purity. The NA column is an extractive distillation using SA as the extractant. Two streams, fresh nitric acid and sulfuric acid, come to the NA column. Concentrated nitric acid flows from the top of the column, and waste sulfuric acid from the bottom and then concentrated in the SAC section and returned to the NA column.