The inferior coal gasification process is usually carried out in the temperature range of 400-1000℃.This process produces a large amount of wastewater which contains high concentration of phenols.At present,solvent extraction is usually used as a pre-treatment to recover phenols in industry wastewater.After most phenols are removed,the wastewater is subjected to a biological treatment process and then discharged.Thus,solvent extraction is a key process to recover phenols.In this work,the solvent extraction process was studied.Based on the properties of coal chemical industry wastewater,methyl butyl ketone (MBK)was chosen as an extraction solvent and its performance on recovering phenols was evaluated.The experimental results show that,MBK is an excellent extractant with high extraction efficiency for both volatile phenols and non-volatile phenols.Furthermore, the effect of extraction process conditions such as temperature and pH value was investigated.When R =1:5 , temperature was 40℃ and pH=8.0,the three-stage countercurrent extraction process reduced total phenols in the coal-gasification wastewater from 12 700 mg/L to 300 mg/L.These experimental results can provide reference for the industrialization of removing phenols from wastewater by MBK.

为评价一种新型高效脱酚萃取剂甲基正丁基甲酮(MBK)在溶剂回收阶段的能耗,借助流程模拟软件,对MBK萃取废水后萃取相和萃余相两部分溶剂的回收过程进行了模拟研究.结果显示,溶剂回收塔理论塔板数为22块,进料板为第14块,回流比0.291 4,粗酚中残留的溶剂质量分数可降低到0.1％,回收的溶剂中酚质量分数降低到0.005％.溶剂汽提塔理论塔板数为5块,废水中残留溶剂质量分数可降低到0.005％.当废水处理量为100 t/h时,用MBK萃取比用甲基异丁基甲酮节省循环冷却水93 t/h,节省中压蒸汽682 kg/h,节省低压蒸汽309kg/h.模拟计算数据可为MBK溶剂回收的工业化应用提供参考.

Three wastewater treatment processes were compared and reasonable suggestions were put forward in the paper. Chemical processes for treating coal-gasification wastewater in China were introduced in different sequences such as acid removing followed by phenol solvent extraction and then solvent recycling and ammonia removing; simultaneous removing of acid gas and ammonia followed by phenol solvent extraction and then solvent recycling; wastewater absorbing acid gas followed by phenol solvent extraction and then simultaneous removing of acid gas and ammonia. The process of simultaneous acid stripping and ammonia removal followed by solvent extraction of phenols had been commercialized.