Various types of apparatus have been suggested heretofore in connection with comminution of material such as rock, coal, etc. The apparatus suggested heretofore in connection with comminution of coal principally for combustion as powdered coal is very expensive. There is a substantial need for equipment capable of comminuting material such as coal so that it may be comminuted more cheaply while at the same time attaining pulverized coal which can be fed for purposes of combustion. The problem is complicated by recent findings that non-coal mineral content of the coal is very often very finely divided and consequently the coal must be finely comminuted in order that it may be processed to achieve satisfactory purification prior to use as a combustion fuel.
The present invention is directed toward a solution of comminution of material such as coal so as to achieve fine comminution not attainable by conventional apparatus with minimum energy input.
It is known to use sonic energy in connection with the comminution of coal. For example, see U.S. Pat. No. 3,284,010. In said patent, the vibratory energy is used to move at least one of a pair of cooperating elements to mechanically crush the coal. Such a construction is less efficient from an energy standpoint than conventional motor means to move one of the elements. The present invention does not use vibratory energy to effet a mechanical comminution of the coal. Instead, I use vibratory energy to supplement a conventional mechanical comminution so that the coal is subjected to a unique combination of forces.