White mud was tested in a coal-fired boiler's pollution control system and was found to be more effective than limestone in removing sulfur. White mud also improved system flexibility and cost efficiency. Chemical analysis showed white mud has lower CaCO3 but higher alkalescency, MgO, Cl-, and activity compared to limestone. Gypsum from white mud had higher water and Cl- content than from limestone, but this can be reduced by adjusting operations. White mud may impact the system, but it is better than limestone in terms of desulfurization and cost.