Dissolution kinetics of cerium from red mud

Leaching kinetics of rare earth element (REE) cerium (Ce) from red mud was investigated using different shrinking core models. The effect of various pertinent parameters such as acid concentration, liquid–solid ratio (LS), average particle size (PS), temperature and leaching time on the leaching efficiency was studied. The maximum recovery of 70.32% was obtained for 2 M HCl solution and an LS of 20:1 v/v. It was observed that the leaching process was limited by diffusion within the porous ash layer of the solid, thus making it ash diffusion controlled. The apparent activation energy was 11.38 kJ/mol, and the Arrhenius constant was 3.36 min?1.