Patent ID: 8021483

Claim:
A method comprising: a) comminuting polycrystalline silicon rods, b) sorting the product of step a) using a step deck classifier to obtain a controlled particle size distribution, and c) removing impurities from the product of step a), step b), or both; wherein the step deck classifier comprises: i) a first deck comprising a) an inlet end of the first deck to a grooved region, b) the grooved region beginning at or near the inlet end of the first deck, where each groove comprises crests and troughs, and c) an outlet end of the first deck, where the outlet end of the first deck is angled such that the crests of the grooves extend out further over a first gap between the first deck and a final deck than the troughs of the grooves, and ii) the final deck positioned downstream of the first gap and below the first deck, the final deck comprising a) an inlet end of the final deck, b) a grooved region beginning at or near the inlet end of the final deck, where each groove comprises crests and troughs, and c) an outlet end of the final deck, iii) a collection container under the first gap for collecting articles that fall through the first gap, and iv) an oversize collection container under the outlet for collecting articles that do not fall through the first gap.