Extraction of the U and Th complexes from natural minerals with supercritical CO<sub>2</sub> :: SPE RESST

Extraction of U and Th complexes from natural minerals with supercritical CO₂

Ukraine has accumulated 42 million tons of radioactive and chemically hazardous substances located on the Earth's surface in the form of dumps and tailings. Recycling of these dumps is one of the most urgent problems of energy and ecology.

Supercritical fluid extraction (SFE) - a promising method for deactivation wastes of nuclear industries in the south-east of Ukraine (fig. 1).

Firure 1

Experimental laboratory studies of SFE-CO2 complexes of actinides from materials-imitators of RAW.

As a sample of depleted uranium ore, granite is used, containing along with uranium complexes significant amounts of iron and other metals.

Extraction was carried out on the SFE-U installation (fig.2), the basic parameters of which are presented in Table 1.

Figure 2 - Installation of SFE-U for working with complexes of actinides released from natural minerals

Table 1 - Basic operating parameters laboratory installation SFE-U

Parameters	Value
Working pressure (compressor КПВ-1А)	0,1 ÷ 20 MPа (1 ÷ 200 atm)
Maximum working pressure	22 МPa
Temperature of the extraction camera	20 ÷ 150 °С
Temperature of restrictor	20 ÷ 100 °С
Maximum flow of CO₂	500 mol/min
Evaporator temperature	20 ÷ 80 °С
Temperature of the receiver	20 ÷ 90 °С
Power consumption	up to 1 kW
Weight (without gas post)	80 kg
Number of continuous extraction cycles	indefinitely

As a result of the extreme study of SFE-CO₂ extraction of uranium complexes from granites, it was shown that it can be used to extract uranium with sufficiently high extraction coefficients from natural materials of complex composition at pressures of carbon dioxide up to 200 atm and temperatures up to 45 °С.

It is shown that the bulk of the uranium complex is extracted with a relatively rapid extraction.

Slow extraction leads to the enrichment of the uranium complex by other components present in the initial sample and interacting with the complexing solutions.