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 centrifuga l ball mill in air and in suspension with the acids mentioned above. P art of the experimental results are qualitatively explained considerin g the partial dehydration of the CaSO4 . 2H(2)O during the activation in air as well as considering the crystal structure disrupted by mecha noactivation. A dissolved fraction, considerably enriched in rare eart hs (compared to the initial phosphogypsum) is obtained as a result of H2SO4 treatment of the samples activated in water solution.