Bypass separator

A separator for separating the larger particles from a powder-air stream such as obtain from a grinding mill and for recovering a power-air stream with a reduced but adjustable powder size distribution, said separator being of the type comprising a housing, means to create a swirl of air moving in one direction to provide a separation zone having an upstream side and a downstream side within said housing, means to admit a particle-air stream to the housing on the downstream side of said separation zone, and means to discharge a powder-air stream from which larger particles have been removed from the housing on the upstream side of the separation zone, the improvement comprising by-pass conduit means having an opening for receiving a portion of the powder-air stream extending into the downstream side of the separation zone and an opening for discharging said portion of the powder-air stream with the powder-air stream from which larger particles have been removed at the upstream side of said separation zone whereby a portion of the original powder-air stream by-passes the separation zone.