Przemysl Chemiczny, Vol.95, No.9, 1740-1743, 2016
Possibility of utilizing waste phosphogypsum in the conversion of calcium sulfate(VI) to calcium carbonate and recovery of rare earth elements from the process
Phosphogypsum and CaSO4 were converted to CaCO3 in reaction with (NH4)(2)CO3, carried out at 37-50 degrees C for 2 h. The conversion degree was 90-100%. The optimum process temp. was 50 degrees C, the phosphogypsum:(NH4)(2)CO3 ratio 1:2.5 and concn. of (NH4)(2)CO3 14%. A presence of La+3 compds. was evidenced. As a by-product, (NH4)(2)SO4 was produced.