Abstract: An ash grinder (30) which is particularly adapted for reducing chunks of fly ash from a flue gas scrubber system to facilitate further handling, includes a rectangular throat section (32) of uniform cross-section with a shaft (52) extending therethrough. The shaft (52) is supported by bearings (54) on pedestals (56) located external to the throat section (32). Sets of perpendicular blades (66, 68) are secured to shaft (52) for rotation between opposite sets of fixed blades (48) located inside the throat section (32). The shaft (52) is driven by a reversible motor (76) through a chain and sprocket arrangement (70, 72 and 74) at a relatively slow speed on a continuous basis so that any large chunks of fly ash formed within the scrubber chamber, such as during a system upset for example, will be reduced to an acceptably smaller size to facilitate further handling without manual intervention or interruption of system operation.