NOVELTY - A cassava drying device comprises polishing pre-drying section, gas-solid separation drying section and air-mixing hot air drying section which are orderly connected. The pre-drying section comprises hearth and hearth on upper part of drying chamber. The drying chamber is provided with wood potato-slag powder wet material inlet and material outlet. The powder wet material outlet is connected with inlet of the gas-solid separation drying section and hearth. The hearth is provided with hot air outlet. The drying chamber further provided with mechanical frying device.    USE - Cassava drying device for firewood making rod and charcoal making device (claimed).    ADVANTAGE - The content of cassava wet slag with water is high as 70% even after mechanical dehydration in process of producing cassava starch. Dried residue with water content is not more than 15%. The firewood rod obtained by dry slag pressing process is further sintered as charcoal product. The charcoal product has low ash content, lower sulfur content, high volatilization and high heating amount. It is excellent biomass energy.    DETAILED DESCRIPTION - Cassava drying device comprises polishing pre-drying section, gas-solid separation drying section and air-mixing hot air drying section which are orderly connected. The pre-drying section comprises hearth and hearth on upper part of drying chamber. The drying chamber is provided with wood potato-slag powder wet material inlet and material outlet. The powder wet material outlet is connected with inlet of the gas-solid separation drying section and hearth. The hearth is provided with hot air outlet. The drying chamber further provided with mechanical frying device. The gas-solid separation drying section comprises dryer with interlayer, where inner cavity of drier is provided with a material inlet and outlet. The interlayer is provided with hot air inlet and outlet. The material inlet is directly or indirectly connected with discharging opening of powder wet polishing predrying section. Material inlet and air inlet of drier are respectively connected with air outlet of the hearth. The back air-mixing hot air drying section comprises pulse air flow dryer, where inlet is connected with material outlet of gas-solid separation drying section. The gas-solid separation drying section with interlayer drier and back air-mixing drying section of pulse air flow dryer of material outlet are respectively connected with cyclone separator. Dehumidification is further connected with gas-solid separation drying section and back air-mixing hot air drying section, where at least one material is provided with fan. INDEPENDENT CLAIMS are included for:    (1) a cassava slag firewood making rod which comprises cassava slag drying unit and forming unit which are orderly connected; and    (2) cassava slag charcoal making device which comprises cassava slag drying unit, material forming unit and carbonizing unit, which are orderly connected.    The cassava slag drying unit comprises the cassava slag drying device.    DESCRIPTION OF DRAWING(S) - The drawing is a schematic diagram illustrating a cassava drying device.