The invention relates to a method for producing, from a waste comprising plasterboard elements (3, 4), an adsorbing granular material (7) containing at least 70% dihydrate calcium sulfate, comprising the steps of selecting (202) a fraction (4) of said plasterboard elements (314) formed by granules (6) having a diameter ranging between a preset minimum value and a preset maximum value drying (203) said fraction (4) or said plasterboard elements (3, 4) at a preset temperature not exceeding 70 °C. Furthermore, the invention relates to a plant for producing (1), from a waste comprising plasterboard elements (3, 4), an adsorbing granular material (7) containing at least 70% dihydrate calcium sulfate, comprising sieving means (30) suitable to separate a fraction (4) of said plasterboard elements (3, 4) formed by granules having a diameter ranging between a preset minimum value and a preset maximum value, drying means (50) of said fraction (4) or of said plasterboard elements (314) at a preset temperature not exceeding 70 °C. Furthermore, the invention relates to an absorbing granule (300, 7, 9, 19, 29) comprising a core (303) which is formed by a fragment of waste of plasterboard panel, containing at least 70% of dihydrate calcium sulfate, said core having a diameter ranging between a preset minimum value and a preset maximum value.
