(中南大学 冶金与环境学院，长沙 410083)
摘 要: 针对现有季铵盐N263合成工艺毒性大、转型步骤冗长和设备要求高等问题，以三辛基甲基溴化铵为催化剂、碳酸二甲酯(DMC)为季铵化试剂替代传统的氯甲烷与N235在高压反应釜中合成甲基碳酸酯季铵盐，考察反应物摩尔比、反应温度、溶剂、催化剂和反应时间等主要因素对叔胺转化率的影响。结果表明：在最适宜的条件下，当N235与碳酸二甲酯的摩尔比为1:5.6、甲醇与N235的体积比为1:2、三辛基甲基溴化铵催化剂为反应体系总质量的5%、反应温度为110 ℃、反应时间为8 h时，叔胺转化率可达99.39%；该甲基碳酸酯季铵盐用3 mol/L H2SO4酸洗、0.6 mol/L NaOH碱洗，转型为 季铵盐；用转型后的 季铵盐按以下比例配成有机相：50%转型后的 季铵盐+30%仲辛醇+20%磺化煤油(体积分数)，在25 ℃下用该有机相萃取钨矿苏打浸出模拟料液(105.7 g/L WO3，100 g/L Na2CO3)，相比O/A=2:1，萃取时间为5 min时，单级萃钨率可达80.88%，有机相饱和萃钨量(以WO3计)为83.92 g/L。
关键字: 甲基碳酸酯季铵盐；碳酸二甲酯；钨；转型；溶剂萃取
（School of Metallurgy and Environment, Central South University, Changsha 410083, China）
Abstract:The synthesis of methyl carbonate quaternary ammonium salt in high pressure reactor was investigated by using dimethyl carbonate (DMC) substituting for traditional methylene chloride as alkylating agent, tri-n-octylmethyl- ammonium bromine as catalyst and N235 as tertiary amine material to solve the problems in the existing quaternary ammonium salt extractant N263, such as toxic synthesis process, long transformation step, and high equipment requirements. The influences of molar ratio of reactants, reaction temperature, solvent, catalyst and reaction time on the conversion rate of tertiary amine were inspected. The results show that under the optimal conditions of molar ratio of dimethyl carbonate to N235 5.6, volume ratio of methanol to N235 1:2, catalyst 5% (mass fraction for reaction system), temperature 110 ℃, reaction time 8 h, the highest conversion of tertiary amine can reach 99.39%. The product was totally transformed to quaternary ammonium salt after the treatment of 3 mol/L H2SO4 and 0.6 mol/L NaOH. Under conditions of extraction temperature 25 ℃, phase ratio (O/A) 2:1, extraction time 5 min, with 50% quaternary ammonium salt in 30% sec-octyl alcohols and 20% sulphonated kerosene as extractant (volume fraction), the single-stage extraction rate of tungsten from autoclave-soda leach solution of scheelite which contains 105.7 g /L WO3 and 100 g/L Na2CO3 is 80.88%, and the saturated loading capacity(for WO3) of organic reaches 83.92 g/L.
Key words: methyl carbonate quaternary ammonium salt; dimethyl carbonate; tungsten; transformation; solvent extraction
