Abstract: A material grinding apparatus (10) includes an annular upper enclosure (12) defining an upper chamber (34) into which material to be ground is introduced from above, a conical lower enclosure (14) defining a lower chamber (36) and supported in tandem with the upper enclosure (12), and one or more angled slots (56) defined in the sidewall of the upper enclosure (12) through which compressed air is introduced relatively circumferentially into the upper chamber (34) so as to generate a circular vortex flow of air and material in the upper enclosure (12) for grinding and drying to take place. The air flow is exhausted by a pipe (92) through an upper end of the upper enclosure (12) and the dried ground material is discharged through an open lower end of the lower enclosure (14). The lower enclosure (14) is a downward continuation and extension of the upper enclosure (12) so as not to extend upwardly into nor past the upper chamber (34) thereof.