Abstract: The invention relates to a process and the respective installation for thermal treatment of granular solids, in particular for producing aluminum oxide from aluminum hydroxide, wherein the solids are heated in at least one preheating stage and then reacted in a reactor at 700 to 1400° C. In at least one preheating stage, the average temperature gradient of the solids amounts to <15K/s and the dwell time of the solids amounts to ?15 s.

Abstract: A method for controlling at least one of a level of solids and an inventory of solids in a solids tank includes withdrawing a stream of solids from the solids tank via a downer. The stream of solids withdrawn from the solids tank is fluidized at a bottom of the downer by supplying a conveying gas so as to convey the withdrawn stream of solids upward via a riser branching off from the downer, a size of the conveyed stream of solids being adjusted by the supplying of the conveying gas. At least one of the level and the inventory of the solids in the solids tank is used as an adjustment variable of a control circuit and a volume flow of the conveying gas is used as an actuating variable of the control circuit.

Abstract: A process for producing metal oxide from a metal salt includes supplying a first part of the metal salt to a hydrate drier so as to indirectly heat the first part of the metal salt in the hydrate drier using a heat transfer medium from a first stage of a multi-stage indirect cooler so as to dry the first part of the metal salt in the hydrate drier and so as to control a waste gas temperature of the process. A second part of the metal salt is guided as a partial stream past the hydrate drier. The metal salt is preheated in a first preheating stage and precalcined in a second preheating stage. The metal salt and a fluidizing gas having a temperature of 150° C. or less are supplied to a fluidized bed reactor so as to calcine the metal salt to form a metal oxide product. The metal oxide product is cooled in at least one suspension heat exchanger and then in the multi-stage indirect cooler.

Abstract: A method for dividing a stream of solids includes discharging the stream of solids via a first downer. The stream of solids are fluidized at a bottom of the first downer by supplying a first conveying gas. By the first conveying gas, a part of the stream of solids are conveyed to a top of a first riser branching off from the first downer. A remaining part of the stream of solids are discharged via a second downer adjoining the first downer. The remaining stream of solids are fluidized at a bottom of the second downer by supplying a second conveying gas. By the second conveying gas, a part of the remaining part of the stream of solids are conveyed to a top of a second riser branching off from the second downer.

Abstract: A process for producing metal oxide from a metal salt includes supplying a first part of the metal salt to a hydrate drier so as to indirectly heat the first part of the metal salt in the hydrate drier using a heat transfer medium from a first stage of a multi-stage indirect cooler so as to dry the first part of the metal salt in the hydrate drier and so as to control a waste gas temperature of the process. A second part of the metal salt is guided as a partial stream past the hydrate drier. The metal salt is preheated in a first preheating stage and precalcined in a second preheating stage. The metal salt and a fluidizing gas having a temperature of 150° C. or less are supplied to a fluidized bed reactor so as to calcine the metal salt to form a metal oxide product. The metal oxide product is cooled in at least one suspension heat exchanger and then in the multi-stage indirect cooler.

Abstract: A method for dividing a stream of solids includes discharging the stream of solids via a first downer. The stream of solids are fluidized at a bottom of the first downer by supplying a first conveying gas. By the first conveying gas, a part of the stream of solids are conveyed to a top of a first riser branching off from the first downer. A remaining part of the stream of solids are discharged via a second downer adjoining the first downer. The remaining stream of solids are fluidized at a bottom of the second downer by supplying a second conveying gas. By the second conveying gas, a part of the remaining part of the stream of solids are conveyed to a top of a second riser branching off from the second downer.

Abstract: A method for controlling at least one of a level of solids and an inventory of solids in a solids tank includes withdrawing a stream of solids from the solids tank via a downer. The stream of solids withdrawn from the solids tank is fluidized at a bottom of the downer by supplying a conveying gas so as to convey the withdrawn stream of solids upward via a riser branching off from the downer, a size of the conveyed stream of solids being adjusted by the supplying of the conveying gas. At least one of the level and the inventory of the solids in the solids tank is used as an adjustment variable of a control circuit and a volume flow of the conveying gas is used as an actuating variable of the control circuit.