Abstract: The causes and mechanisms of abnormally colored products such as blue and pink in the production of ammonium sulfate in the spray saturator were analyzed．The key reason was found that the proportion of impurities such as phenol and cyanide contained in ammonia vapor during the ammonia stripping was locally too large，making the acidity uncontrolled，and the prussian and quinone adhered to the product，resulting in abnormal color of the product．The amount of ammonia stripping is adjusted according to the output of the coke oven so that it can be produced continuously．By such an optimized operation，the problem of abnormal ammonium sulfate products is solved.

Key words: Ammonium sulfate, Acidity, Ammonia stripping, Prussian, Quinone