To provide a vertical drying furnace which is inexpensive, simple in construction of its furnace and high in heat transfer efficiency without the need of agitation of a substance to be dried and rotation of a device because gas-solid heat exchange is carried out in an air current.

Refuse is fed into a dryer from a refuse feed port 4 and crushed by a crusher 7 equipped with rotary blades. Hot air 11 blown from a hot air inlet 1 blows up the crushed refuse and turns into an updraft 15 that rises along a vertical air duct 5. Heavy materials such as metals, glass, etc., contained in the crushed refuse drop on to a lower stage of a furnace, are carried by a conveyer 2 in the direction shown by an arrow 12 and discharged from a discharging port 3. A mixed flow 16 of air and the entrained refuse is discharged form an outlet 6 on an upper stage and sent to a cyclone where gas-solid separation takes place. Thus, the dryer has three functions of crushing, drying and air-classifying and can be used as a major device for a refuse treatment processing apparatus.