Abstract: In a device for coating granular solids of the type having a double-cone rotary drum which is perforated so as to permit the flow of air or gas into and out of the rotary drum and which is tiltable about the axis at right angles of the axis of rotation of the rotary drum so that in the case of the discharge of product solids, the discharge opening of the rotary drum may be directed downwards, axially annular insulating covers are provided which ensure the effective thermal insulation of the rotary drum when the hot air or gas is blown thereinto. The present invention further provides means which are very effective in gas-tightly sealing the gas supply and exhaust passages defined in the duct around the rotary drum and the annular covers attached thereon so as to provide the air thermal insulation layers.

Abstract: A device for coating granular solids has a rotary drum and a casing or housing air-tightly housing the rotary drum. The space between the rotary drum and the casing is divided by sealing means into a gas supply passage and a gas exhaust passage which in turn are communicated with a gas supply duct and a gas exhaust duct, respectively. The rotary drum is of a double-cone structure consisting of a cylindrical section and frustoconical side walls, and the cylindrical section consists of a plurality of circumferentially arcuated louvers overlapped one upon another and radially spaced apart from each other at a suitable distance to define gas passages between the interior and exterior of the rotary drum.