Nitric Acid Treatment

Introduction

Nitric acid is one of the most common mineral acids in the chemical Industry. It is produced by a high temperature oxidation of ammonia with oxygen catalyzed by a platinum/rhodium contact providing with water nitric acid with a strength of up to almost 68wt% can be generated. The majority of this nitric acid is used for the production of fertilizers. Other processes such as the production of explosives, pigments, rocket fuels or polyurethanes require higher concentrated nitric acid. For the concentration it has to be considered that nitric acid and water form an azeotrop at 68wt% of nitric acid as show below.

The concentration of nitric acid up or close to the azeotropic point is realized "simple" rectification called pre-concentration. The high concentration process of nitric acid passing the azeotrpic point up to 99,8wt% is realized by extractive rectification with sulfuirc acid. During this concentration process NOx gases are generated and partially dissolved in the produced liquid nitric acid. In most cases the nitric acid needs to be free of NO_x so that a bleaching respectively stripping process with air is the subsequent process step to get clear concentrated nitric acid. The generated NOx-gases are convertered into nitric acid and recycled to improve the over all process efficiency and to avoid NOx emissions.

Nitric acid used for nitration processes is commonly mixed with sulfuric acid to become a mixture called nitration acid. The nitric acid thereof is not reacting quantatively during the nitration process so that the recovery of the acids is important for the cost efficiency of the overall nitration process and for the environment reducing nitrates in waste waters. For the recovery, the cleaning respectively the so called denitration and further purification of nitric acid from various waste and feed streams De Dietrich Process Systems has developed optimum processes and realized numerous plants worldwide. 

The plants for these QVF® processes are built with highly corrosion resistant components made of QVF® borosilicate glass 3.3 and De Dietrich® glass-lined steel manufactured by De Dietrich Process Systems. Therefore De Dietrich Process Systems as the manufacturer of these components has developed throughout the last decades processes to handle nitric acid such as:

• Pre-concentration of nitric acid
• Production of high concentrated nitric acid up to 99,8wt%
• Bleaching of nitric acid
• Production of nitric acid from NO_x
• Recovery of nitric acid from various waste streams
• Recovery of nitric and sulfuric acid from nitration processes
• Decomposition and removal of organic components from nitric acid
• Purification of nitric acid up to electronic grade

The design of these processes is always optimized for the utilities avaiable at your site.

Optimization and adaptation of these processes according to your feed stream and your quality specification of the product can be carried out by us in our test facility.