PURPOSE: To reduce the adhesion of a stock material to an inlet chamber, by branching a part of a particulate stock material to the final stage cyclone of a preheater to provide a branched stock material supply chute bypassing the final stage cyclone.

CONSTITUTION: A particulate stock material is supplied to a suspension preheater from a feeder 4 and passes through cyclones 6, 7, 8 where about 95% of said stock material enters a rotary kiln 1 from the cyclone 9 through an inlet chamber 2 and baked while about 5% of the remainder bypasses the cyclone 9 to be directed to the kiln tail part of the rotary kiln 1 through a branched stock material chute 10 and sprayed in the direction opposed to the exhaust gas stream 14 in the kiln 1 to be mixed with exhaust gas and reversed as shown by the arrow 15 to rise through a rising duct 3. High temp. kiln exhaust gas is exhausted from a main exhaust fan 5 through the inlet chamber 2 and, at this time, contacted with the stock material.