| 摘要 |
PURPOSE:To industrially and advantageously treat a process waste liquor discharged from a process for producing methacrylic acid or methyl methacrylate by the acetone cyanhydrin method, by treating the above-mentioned waste liquor to reduce the COD value, and utilizing the resultant waste liquor as part of an acid for decomposing rock phosphate. CONSTITUTION:Methacrylic acid or methyl methacrylate is produced by the acetone cyanhydrin method. In the process, a waste liquor (1) discharged from an esterification tank or hydrolysis tank is cooled to remove scum. The resultant waste liquor (2) is then subjected to a distillation step. For example, the waste liquor (2) is subjected to steam distillation at about 110-150 deg.C, and the bottoms are cooled to <=100 deg.C to remove floating organic materials and give a treated waste liquor (3) having <=25g/l (measured by the Mn method at 100 deg.C) COD, which is then used as part of an acid for decomposing rock phosphate in the wet process for producing phosphoric acid. The above-mentioned waste liquor (1) contains 44-54% acid ammonium sulfate, 14-20% sulfuric acid, 25-35% water and further several % organic materials and exhibits 30-50g/l COD value.
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