Multi-layer sedimentation type coating and drying device and method for preparation of coated fertilizer

The invention provides a multi-layer sedimentation type coating and drying device and method for preparation of a coated fertilizer and belongs to the technical field of agricultural fertilizer preparation. In a barrel inner cavity of the device, at least two layers of horizontally parallel trays are arranged in a coating fluidized bed section, at least one spray gun is arranged on each layer of trays in the section, and a conveying pipe is connected to the spray gun. At least two layers of horizontally parallel trays are arranged in the drying fluidized bed section. Each tray comprises a hollow column body and a hollow table body, a blanking hole is formed in the bottom wall of the hollow table body, a rotating plate for opening or closing the blanking hole is movably mounted at the lower part of the hollow table body, and a ventilation hole is formed in the rotating plate. In the method, coating and heating aftertreatment are continuously carried out, the fertilizer sequentially passes through the trays under the action of gravity and tray guide flow, and coating and drying treatment is finished. The device has the advantages that traditional batch type fluidized bed coating equipment is changed into multi-layer sedimentation type equipment, and the production efficiency is improved by three to ten times; meanwhile, the heat energy and the kinetic energy of wind are fully utilized, and energy consumption is reduced.