High efficiency impact mill

An apparatus for pulverizing material, the apparatus comprising:

• a housing defining an interior wall of a grinding chamber;
• an inlet conduit positioned at an axial input end of the grinding chamber and configured to feed the material vertically downward into the grinding chamber;
• an outlet conduit positioned at an axial output end of the grinding chamber and configured to direct the pulverized material vertically upward from the grinding chamber;
• a shaft axially traversing at least a part of the grinding chamber;
• an axial flow path extending between the inlet conduit and the outlet conduit, parallel to the shaft;
• hammers extending radially outwardly from the shaft, the hammers being circumferentially spaced and respectively having attachment ends and heads, the hammers being in pivotal relation to the shaft about a pivot pin and are movable on impact with the material;
• and
• annular baffles located axially along the flow path, at least a portion of the annular baffles located above and eclipsing a width of the shaft, each of the annular baffles having an outer circumference and an inner circumference and being attached along the outer circumference to the interior wall of the housing such that the annular baffles are coaxial with the shaft and the inner circumference extends into the grinding chamber adjacent the heads of the hammers, the annular baffles extending continuously along an entirety of the interior wall perpendicular to a direction of flow of air and material parallel to the shaft to promote residence time of the material in proximity to the hammers as air and the material flows through the mill parallel to the shaft, wherein the hammers pivotal relation to the shaft comprises a swinging movement about the pivot pin, in a circumferential direction during operation of the mill;
• wherein each of the hammers has a radially outward facing outermost extent and each of the annular baffles has a radially inward facing innermost extent, the radially outermost extent of at least one of the hammers extends radially outward beyond the radially innermost extent of at least one of the annular baffles, by a radial distance;
• and
• comprising a variable speed motor configured to rotate the hammers within the grinding chamber, wherein varying the speed of the motor, in conjunction with the baffles, affects residence time and magnitude of impact grinding force acting on particles of the material.