Abstract: The invention relates to a method for regulating the sand discharge by means of a discharge pipe located on the opposite side of a sand charging means of a fluidized bed kiln in connection with the thermal regeneration of old foundry sand, in which the base of the fluidized bed kiln has openings through which the hot gases pass into the fluidized bed. The method is characterized in that the sand exit from the discharge pipe (4) is freed by increasing the air supply in a pneumatic conveyor (5) following the fluidized bed kiln (1) through its perforated base (7) in such a way that the pouring cone (6) formed between the end of the discharge pipe (4) and the base (7) is decreased and consequently the exit of the discharge pipe (4) is freed.

Abstract: A process for thermically recovering old sand obtained in casting plants and for treating dust containing combustible organic components and incombustible inorganic components is disclosed. Dust obtained by mechanical preparation of the old sand is separated from the sand. The sand is used to form a fluid bed in a fluid-bed kiln having a post-combustion space and an outlet for releasing combustion gases. Dust containing combustible organic components and incombustible inorganic components is introduced into the fluid bed, the combustion of the organic components being used to maintain reaction temperature in the fluid bed. The heat of the fluid bed and the post-combustion space deactivates inorganic components of the dust, which are transported by released combustion gases to effectively separate the inorganic components of the dust from the thermically recovered old sand. These deactivated inorganic components of the dust can be separated from the released combustion gases for easy disposal.