A process for producing prills, in particular fertilizer prills, coated with at least one biologically degradable polymer layer, in particular a PLA layer, may involve applying a degradable polymer layer to a carrier material of the respective prill in a drum coating step, in particular in a drum coater at relative negative pressure, and then coating the prills with a second degradable polymer layer on top of the first degradable polymer layer in a fluidized bed coating step, in particular in a fluidized bed coater at a relative positive pressure. Coating the prills with the second degradable polymer layer may involve introducing the prills into a fluidized bed coater after the drum coating step, and the fluidized bed coating step may be performed spatially adjacent alongside the drum coating step.
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