Method for pulverizing silicon particles by fluid jet energy

In generating silicon seed particles of about 100-1,000 microns by pulverizing silicon feed particles of about 300-3,000 microns, a method which comprises the steps of:

• providing a single pulverizing chamber having a lower section and an upper section both disposed along an axial direction of said chamber with a jet nozzle disposed in said lower section;
• introducing said silicon feed particles into said pulverizing chamber through an inlet hole positioned at the wall of said pulverizing chamber:
• providing a jet stream in said axial direction of said pulverizing chamber with a jet velocity of about 300-10,000 m/sec at a jet nozzle outlet by introducing a stream of gas through said jet nozzle, and thereby accelerating silicon particles near said jet nozzle into collision with each other and pulverization thereof so that said seed particles are generated;
• allowing said jet stream to expand into said upper section of said pulverizing chamber so that the expanded gas flows axially upward through said chamber;
• maintaining the average gas velocity in said upper section of said chamber in a range of about 0.5-30 m/sec so that relatively small silicon particles below a predetermined size are caused to rise up within said upper section;
• maintaining the particle density below about 0.2 between said jet nozzle outlet and a vent hole in the wall of said upper section, and thereby providing a dilute-phase fluidized bed without an upper boundary above said jet nozzle such that relatively large particles over said predetermined size in said upper section fall by gravity and re-pulverize in said jet stream;
• and
• providing the cross-sectional area of said vent hole substantially smaller than that of said upper section of said pulverizing chamber so that said small silicon particles in said upper section are effectively removed out of said pulverizing chamber through said vent hole.