二(2-乙基己基)磷酸(简称P_(204)是一种酸性磷型萃取剂。本文采用P_(204)的正己烷溶液从盐酸体系中萃取钐,确定了其萃取机理和萃合物的组成,测定出表观萃取平衡常数;并用P_(204)的磺化煤油溶液对钐的萃取条件及负载有机相的反萃条件进行了筛选。实验表明:当起始水相的PH值等于3.86时,萃取率达99.54％,而采用2N盐酸进行二级反萃,反萃率高达99.68％。 Di (2-ethylhexyl) phosphoric acid (abbreviated as P 204) is an acidic phosphorus extractant.In this paper, samarium was extracted from hydrochloric acid system by using n-hexane solution of P_ (204), and its extraction mechanism and extraction , And the apparent equilibrium constant of extraction was determined. The extraction conditions of samarium and the stripping conditions of loaded organic phase were also screened with sulfated kerosene solution of P 204. The experimental results showed that when the pH value of the initial aqueous phase was equal to 3.86, the extraction rate of 99.54%, while the use of 2N hydrochloric acid secondary stripping, stripping rate as high as 99.68%.