Device for implementing a method of granulating slag fines including a conveyable removable platform (1) on which there are arranged at least one device for the selective obtaining of fines (10) upstream of a feed hopper (5), a granulator (2) fed with the fines by the feed hopper (5), a storage reservoir (9) for a granulation aqueous phase feeding of the granulator (2) with the aqueous phase, a power source (4) and a monitor and controller (3) for producing granules from the fines.