Multi-level furnace and method for thermal treatment of a material flow

A method for the thermal treatment of a material flow in a multi-level furnace, the material flow being treated in at least two process chambers arranged one above the other and separated gastightly from one another and respectively equipped with at least two floors for the levels, and the material flow being transferred by a transfer device from an upper process chamber to a lower process chamber,

• wherein a column of material is formed in the transfer device for the gastight separation of the two process chambers, the forming of the column of material being performed by at least one delivery unit or at least one chute or a slider and the at least one transfer device being used not only for transferring the material flow from the upper process chamber to the lower process chamber but also for discharging at least part of the material flow from the multi-level furnace and/or for introducing material into the multi-level furnace from outside, and
• wherein the material flow is treated in at least three process chambers gastightly separated from one another, part of the material flow being fed from an upper process chamber to a lower process chamber while bypassing a middle process chamber.