LAUSR

Abstract Calcium sulphoaluminate (3CaO·3Al 2 O 3 ·CaSO 4 , abbreviated as C 4 A 3 S) was synthesized by sintering at 1375 °C for 2 h with analytically pure carbonate calcium, alumina and dihydrate calcium sulfate. The crystal structure of C 4 A 3 S was characterized by XRD, SEM and TEM. Alumina leaching properties in Na 2 CO 3 solution were studied, and the leaching mechanism was investigated by means of Raman spectrum and XRD. The results show that C 4 A 3 S has porous morphology. The polycrystallines and single crystals coexist in C 4 A 3 S and grow along different directions. The alumina leaching rate of C 4 A 3 S is 98.41%, which is higher than that of 12CaO·7Al 2 O 3 under the optimal condition. The aluminum and sulfur elements exist in the leaching solution in the form of Al ( OH ) 4 − and S O 4 2 − , respectively, and the calcium exists as CaCO 3 in the leaching residues.