US Patent 7490785 Process and apparatus for comminuting silicon

An apparatus for producing silicon seed particles having a size of from 50 μm to 1000 μm from silicon granules having a size of from 300 μm to 5000 μm, comprising a vertically disposed jet chamber with a low cross sectional area and a jet nozzle at the base of the jet chamber through which a milling gas stream is introduced into the chamber; a larger cross section countercurrent gravity separator adjoining the jet chamber, and an inlet for silicon granules, wherein the jet chamber has a length sufficient to allow the milling gas stream to widen to the cross section of the jet chamber.