| Abstrakt: |
The extraction of Nb and Ta from tantalo-columbites of San Luis, Argentina has been studied at the laboratory scale. The ore mixed with carbon was chlorinated in a fixed bed reactor operated with downcoming flow and pressures close to atmospheric. The variables investigated were: ore/carbon ratio, mixing time and procedure; temperature and reaction time; particle size and previous ore treatment with HCl, EDTA and NaOH solutions. The results obtained showed that: the optimum percentage of carbon varies with temperature; Nb and Ta recovery is hardly affected by the mixing time; the influence of the mixing procedure is important; recovery increases both with higher temperature and with longer reaction times, and decreases with larger particle size; in general, ore leaching led to a decrease in the solid reactivity to the chlorination process. The solids were characterised by BET, XRD, XRF, SEM and optical microscopy. Quantitative chemical analyses were carried out by XRF, ICPAES, gravimetry and UV-Visible spectrometry. |
