Method for producing ammonium nitrate using nitrogen dioxide in cement exhaust gas

A method for producing ammonium nitrate using nitrogen dioxide in a cement exhaust gas, the method comprising:

• a nitrogen dioxide recovery step (1) of bringing nitrogen dioxide in a cement exhaust gas into contact with water and absorbing the nitrogen dioxide in the water to recover the nitrogen dioxide as a nitrate/nitrite nitrogen-containing solution;
• a reduction reaction step (2) of bringing reduced iron and magnetite into contact with all or a part of the nitrate/nitrite nitrogen-containing solution obtained in the nitrogen dioxide recovery step (1) under an acidic condition to produce iron hydroxide and ammonia;
• an ammonia recovery step (3) of distilling and vaporizing the ammonia produced in the reduction reaction step (2) using a waste heat gas from a cement manufacturing process to recover the ammonia;
• a solid-liquid separation step (4) of separating a residue after recovering the ammonia in the ammonia recovery step (3) into a solid and a liquid, and by which the residue is separated into the iron hydroxide of the reduction reaction step (2) which has passed through the ammonia recovery step (3), and unused nitrate/nitrite nitrogen-containing solution in the residue;
• a neutralization step (5) of bringing the nitrate/nitrite nitrogen-containing solution separated in the solid-liquid separation step (4) and the nitrate/nitrite nitrogen-containing solution, which is a remainder obtained in the nitrogen dioxide recovery step (1) and not introduced into the reduction reaction step (2), into contact with the ammonia vaporized and recovered in the ammonia recovery step (3) to prepare ammonium nitrate;
• and
• a catalyst production step (7) of preparing the magnetite used in the reduction reaction step (2) by reacting iron sulfate with a sodium hydroxide aqueous solution and then separating the produced magnetite and sodium sulfate aqueous solution into a solid and a liquid,
• separating the sodium sulfate aqueous solution by electrodialysis into sodium hydroxide and sulfuric acid, and using the obtained sodium hydroxide in a circulatory manner in the preparation of the magnetite by reacting the sodium hydroxide with the iron sulfate.