苯酐是重要的化工原料，目前國內外苯酐的方法主要有萘氧化法和鄰二甲苯氧化法，兩種方法在苯酐凈化過程中都有黑褐色精餾殘渣產生。該廢料中含有大量苯酐，同時含有部分黑色焦油和高聚物，無法進行直接利用。
Phthalic anhydride is an important chemical raw material. At present, naphthalene oxidation and o-xylene oxidation are the main methods to produce phthalic anhydride at home and abroad. Both methods produce dark brown rectification residues in the purification process of phthalic anhydride. The waste contains a large amount of phthalic anhydride, as well as some black tar and polymers, which cannot be directly produced and utilized.
目前有各種回收方法，其中比較多的有溶劑萃取法、升華法和反應深加工處理法等。但各種工藝均不能很好的滿足實際要求。本研究按某廠提出的產品不含焦油、收率高、成本低的要求，采用簡單合理的回收工藝可回收幾乎廢料中的全部苯酐，產品質量好。采用該法處理回收某廠苯酐廢料６００噸，可年產粗苯酐近５００噸，再結合工廠的需要將該苯酐返回到苯酐裝置出工業優級品，不影響苯酐裝置的正常。該技術可降低苯酐成本，為工廠帶來一定的經濟效益。目前國內苯酐能力估計為７０萬噸，按２％計算可年產廢料１．４萬噸，估計可回收１萬多噸苯酐。若該技術推廣全國或向國外轉化技術將具有很好的經濟和社會效益。該技術成熟，達到水平。
At present, there are various recovery methods, among which solvent extraction, sublimation and reaction deep processing are more common. However, various production processes can not meet the actual requirements very well. In this study, according to the requirements of a factory that the product contains no tar, has high yield and low cost, a simple and reasonable recovery process can be used to recover almost all phthalic anhydride in the waste, and the product quality is good. This method is used to treat and recover 600 tons of phthalic anhydride waste from a certain factory, which can produce nearly 500 tons of crude phthalic anhydride annually. Combined with the needs of the factory, the phthalic anhydride is returned to the phthalic anhydride production unit to produce industrial high-grade products, which will not affect the normal production of the phthalic anhydride unit. This technology can reduce the production cost of phthalic anhydride and bring certain economic benefits to the factory. At present, the domestic production capacity of phthalic anhydride is estimated to be 700000 tons. According to 2% calculation, 14000 tons of waste can be produced annually, and it is estimated that more than 10000 tons of phthalic anhydride can be recovered. It will have good economic and social benefits if the technology is popularized nationwide or transferred to foreign countries. The technology is mature and reaches the international advanced level.
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