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: The invention relates to a process for the mechanical cleaning of foundry used sand by means of thermomechanical regenerations, in which the sand is blown pneumatically against a deflection hood and the mechanical-pneumatic cleaning is performed batchwise in a separate container. The process can be used both as pre-cleaning and as after-cleaning. In the case of pre-cleaning there is a simultaneous drying, preheating, pre-cleaning and sifting, whereas with after-cleaning there is a simultaneous cooling, after-cleaning and sifting. As a result of the batchwise operation, all the quartz particles are exposed roughly to the same friction treatment and consequently, in conjunction with a simple control of the cleaning process, reduced grain destruction is achieved.

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.

Abstract: In a process for reclaiming foundry scrap sand, containing organic and inorganic binders, the comminuted foundry sand is precleaned in a dry state by allowing it to impinge and/or by grain-against-grain friction, is regenerated by thermal treatment, and is subsequently subjected to a final cleaning in the dry state, separated slurry materials being separated from the regenerate by a gas stream. An apparatus for conducting the process comprises a rotary drum (5, 46, 107) and/or a shotblasting cleaner (102) for precleaning, a fluidized-bed furnace (9, 51, 108) for thermal regeneration, and a further rotary drum (10, 59, 109) and/or a further shotblasting cleaner (151) for the final cleaning, and is accommodated in several container-type vessels (I through IX) which latter can be set up in superimposed relationship.