A heat treatment apparatus has a first screw conveyor, a second screw conveyor, a first nozzle pipe, and a second nozzle pipe. If the first screw conveyor rotates right, the first nozzle pipe is disposed on the left lateral side of the first screw conveyor. If the first screw conveyor rotates left, the first nozzle pipe is disposed on the right lateral side of the first screw conveyor. If the second screw conveyor rotates right, the second nozzle pipe is disposed on the left lateral side of the second screw conveyor. If the second screw conveyor rotates left, the second nozzle pipe is disposed on the right lateral side of the second screw conveyor.