Study on Direct Extraction of Uranium from Uranium Oxides Powder Using Supercritical CO₂

The factors with effects on direct extraction of uranium from uranium oxides powder is studied using supercritical CO₂/TBP-HNO₃ extraction system.The results show that the extraction efficiency of uranium（E_U） is increasing obviously with an increased HNO₃/TBP,and E U is the best at the ratio value of 1.4;Under certain HNO₃/TBP,E_U is direct proportional to the volume of organic phase.The extraction reaction can be divided into three phases: react slowly in initial phase,fast in stable phase and slowly in final phase due to powder condition;As temperature increasing,E_U has maximum value 91.4% at 60℃;As pressure increasing,E_U has maximum value 94.7% at 12 MPa;According to extraction equipment condition,the best separation of extraction products can be achieved in 8 MPa（separation vessel 1） and 5 MPa（separation vessel 2）.