Abstract
The phosphate rock contains trace amounts of uranium and lanthanides. When treating this rock with H2SO4 produces phosphoric acid together with 5 times of its quantity of phosphogypsum (PG) precipitate as a by-product. The lanthanides in the rock are mostly present in the PG. After a slight modification of the precipitated PG, some portion of the PG is used as a low-grade phosphate fertilizer (PGF) containing similar to 2% P2O5. Leaching of different lanthanides from PGF by the mineral acids solutions namely; HCl, H2SO4 and HNO3 is investigated in relation the acid concentration, the mixing time, and acid volume to mass of PGF ratio (L/S) as well as temperature. It is found that the highest leaching efficiency was obtained using 3.0 M HNO3, L/S = 3.0 and mixing time of 3.0 hr, at room temperature. The total lanthanides content in the PGF, was found to be about 480 mg/kg. After three cycle of leaching, the leached out lanthanides from PGF was more than 66 %.