| Popis: |
The thorium concentration in monazite can be as high as 6-15 wt. % and it has the potential to be used in the nuclear power system as fuel. Thorium is predominantly present in the form of thorium orthophosphate (Th3(PO4)4) along with the other rare-earth phosphates [Ce, La, Nd, Pr, Sm (PO4)] in the monazite mineral. The alkaline decomposition method was applied for leaching out Thorium (Th) from monazite. In this study, the effect of monazite particle size (75, 150, and 250 µ) and leaching temperature (373, 393, 423, and 453 K) on the kinetics of thorium leaching were investigated using MATLAB software based on the rates of mass transfer, heat transfer, and chemical reactions. The model was constructed centered on the shrinking core model (SCM) for the isothermal condition to evaluate the rate of thorium leaching from monazite. Based on the simulation results, the particle size has a more significant effect on the Thorium leached than leaching temperature. About 90% of Th fraction was leached after 35 min at the maximum leaching temperature of 453 K for 75 µm particle size, while it takes a longer time for 150 and 250 µm particle size, respectively. In general, the model followed a similar trend for all the leaching temperatures, with a considerable increase in leaching time for larger particle sizes. |
