Precipitation of uranium from alkaline liqueurs

IVANA OROZCO; MARINA ROMERO; RODOLFO LARA; VANESA BAZAN

REVISTA MATéRIA

UNIV FED RIO DE JANEIRO

Lugar: Rio de Janeiro; Año: 2018

1517-7076

In Argentina there is uranium with abundant organic matter and variety in quantity of sulfides and carbonateswhich act as cement or sealing joints. The latter minerals modify directly the choice of metal leaching processfor the concentration of uranium. The most beneficial selected process turns out to be the alkaline leaching.Once this process has been finished, using the lixiviante agent such as Na2CO3 NaHCO3 in presenceof oxidizing agent, the hexavalent state of uranium as U3O8 has been achieved. In this research the experimentaldesign is proposed at the laboratory level, in order to obtain the precipitation of uranium from alkalineleach liquors using two different precipitation mechanisms. One of them uses a strong oxidizing agent suchas excessive hydrogen peroxide. Stoichiometrically, 0.9 g of H2O2 were used, obtaining the uranium precipitationas UO2*2H2O. The working variables are lightly acidic pH values, for values between 2.5, 4 to 5 andreaction times with mineral exposure of 1, 2, 3 and 4 hours. Working temperatures are 25 °C, 60 °C and 80°C for a constant stirring speed of 400 rpm. In the other mechanism, a precipitating agent such as NaF in alkalinemedium is added, without modifying the pH of leached liquors, generating an insoluble compoundsuch as NaUF6. For this purpose we worked with different: concentrations of the precipitating agent, stirringspeed and precipitation times. However, the first mechanism proved to be the best. Uranium recovery values were found for working conditions of pH: 2.5; temperature of 60 ºC and reaction times higher than 3 h until 4h.