Influence of mechanoactivation on rare earths leaching from phosphogypsum

The influence of mechanoactivation on the overall solubility of CaSO4 . 2H(2)O and of phosphogypsum in water and in diluted acids (10% HCl, 7% H2SO4) as well as on the leaching of rare earths from phosphogypsum have been studied. The mechanoactivation is performed in a centrifugal ball mill in air and in suspension with the acids mentioned above. Part of the experimental results are qualitatively explained considering the partial dehydration of the CaSO4 . 2H(2)O during the activation in air as well as considering the crystal structure disrupted by mechanoactivation. A dissolved fraction, considerably enriched in rare earths (compared to the initial phosphogypsum) is obtained as a result of H2SO4 treatment of the samples activated in water solution.