ABSTRACT
In Argentina there is uranium with abundant organic matter and variety in quantity of sulfides and carbonates which act as cement or sealing joints. The latter minerals modify directly the choice of metal leaching process for 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 presence of oxidizing agent, the hexavalent state of uranium as U3O8 has been achieved. In this research the experimental design is proposed at the laboratory level, in order to obtain the precipitation of uranium from alkaline leach liquors using two different precipitation mechanisms. One of them uses a strong oxidizing agent such as excessive hydrogen peroxide. Stoichiometrically, 0.9 g of H2O2 were used, obtaining the uranium precipitation as UO2*2H2O. The working variables are lightly acidic pH values, for values between 2.5, 4 to 5 and reaction 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 alkaline medium is added, without modifying the pH of leached liquors, generating an insoluble compound such as NaUF6. For this purpose we worked with different: concentrations of the precipitating agent, stirring speed 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.
Keywords
uranium precipitation; alkaline leaching
