Abstract: Particles of non-smokable material are segregated from a flow of a mixture of smokable and non-smokable materials by subjecting the flow to a first segregating treatment which divides the flow into a first stream consisting practically exclusively of smokable material, and a second stream constituting a relatively small percentage of the flow and containing substantially all of the non-smokable material and the remnant of smokable material. The second stream is treated for a second time, preferably at the discharge end of a pneumatic conveyor system including at least one conduit, to segregate the non-smokable material from the remnant of smokable material which latter can be admitted to the first stream. The segregating device which divides the flow into the first and second streams is or can be utilized to treat the second stream, i.e., to segregate smokable material of the second stream from the non-smokable material of the second stream.