PURPOSE: To make it possible to smoothly pay out raw materials, by providing an air duct communicating between the upper part of the lateral wall of a first trough installed in the botom pay-out port of a hopper and the tank top part of the hopper to prevent the raw materials from solidifying in the vicinity of the lateral walls of the first trough.

CONSTITUTION: A first trough 7 having its bottom closed, for a transverse feed conveyor, is installed in the bottom due-out port of a hopper 1, and a second trough 9 having its cross-sectional feed area smaller than that of the first trough 7, for a transverse feed conveyor is connected to one lateral wall 8 of the first trough 7. Further, a first screw conveyor 10 is laid extending from the inside of the first trough 7 to the inside of the second trough 9, and as well a second screw conveyor 11 for transversely feeding raw materials toward the side of the trough 9 is disposed in the inside of the trough 7. Further, the upper position of the trough lateral wall 8 to which the trough 9 is connected is communicated with the tank top part 9 of the hopper 1 by means of an air duct 16. With this arrangement, the raw materials in the vicinity of the lateral wall 8 may be contacted with air to prevent deaeration of the materials due to the feed by the screw conveyor 11, thereby the raw materials in the vicinity of the lateral wall 8 may be prevented from being solidified.