研究了新萃取剂吡啶从硝酸介质中萃取铀的机理。考察水相硝酸浓度、萃取剂浓度、盐析剂硝酸钠以及振荡时间和温度对萃取分配比的影响 ,确定了萃合物的组成。求得萃取硝酸铀酰过程的平衡常数及反应的热力学函数。同时研究了相比的影响 ,以及稀释剂的影响。发现吡啶萃取能力在不同稀释剂中由弱到强的顺序为 :四氯化碳、氯仿、苯、甲苯、环己烷、煤油。 The mechanism of extraction of uranium from nitric acid by pyridine as a new extractant was studied. The effects of concentration of nitric acid in aqueous phase, concentration of extractant, sodium nitrate as salting-out reagent, and the time and temperature of shaking on the extraction and distribution ratio were investigated. The composition of the extract was determined. The equilibrium constants of extraction of uranyl nitrate and the thermodynamic functions of the reaction were obtained. At the same time, the impact of the comparison, as well as the effect of the diluent, was studied. Found that pyridine extraction ability in different diluents from weak to strong order: carbon tetrachloride, chloroform, benzene, toluene, cyclohexane, kerosene.