The invention employs a folding arm conveyor that rotates horizontally. The folding arm conveyor is mainly composed of an undercarriage mounted on the ground of a stockyard, a tower body mounted on the undercarriage, a balance arm, a conveying arm, a tower top, and other main components, wherein the balance arm, the conveying arm, and the tower top are mounted on the tower body. The conveying arm is provided with two portal frames (I) and (II) and an unloading trolley. The tower body is provided with a gyration apparatus and a hopper. The balance arm is provided with a balance trolley. The folding arm conveyor can rotate horizontally, and the conveying arm can be folded and retraced by controlling the wind rope by the windlass, so that the folding arm conveyor can be prevented from colliding with other devices or buildings during the rotation.