Impact Mill consists primarily of a serious of hinged of fixed hammers revolving in an enclosed chamber lined with cast, wear-resistant plates. Grinding results from a combination of hammer impact on the larger particles and attrition of the smaller particles on one another and across the grinding surfaces. An air system with the fan mounted either internally or externally on the main shaft induces a flow through the mill. An internal or external type of classifier may be used. This class of mill is simple and compact, is low in cost, and may be built in very small sizes.