Method for recovering aluminum vapor and aluminum suboxide from off-gases during production of aluminum by carbothermic reduction of alumina
AssigneesAlcoa Inc., Elkem ASA
InventorTor Lindstad
Life of this patent
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Abstract
A method for aluminum recovery during the carbothermic production of aluminum in a smelting furnace (1,2) is disclosed, where during carbothermic reduction of alumina, aluminum and aluminum suboxide vapors are produced (3, 4), which are reacting with carbon. Reactive carbon is generated in situ by the cracking of hydrocarbon compounds (6) in a separate closed reactor vessel (5) at a temperature greater than about 1955° C. Solid aluminum carbide that formed during the reaction can then be recycled by a conduit (8) to the primary reactor for reduction to aluminum, and reactor gas (10) can be fed to a cooler (9).
Claims14
A method for recovering Al components from an off-gas produced during carbothermic production of aluminum, where the off-gas comprises CO, Al vapor and aluminum suboxide comprising:
- a) directing said off-gas to an enclosed reactor kept at an elevated temperature;
- and
- b) supplying to the enclosed reactor one or more gaseous or liquid hydrocarbon compounds that will form solid carbon and hydrogen gas upon heating;
- wherein the hydrocarbon compounds crack to form carbon and hydrogen in the enclosed space and the carbon formed reacts with the Al and aluminum suboxide in the off-gas to produce Al4C3.
In a method for producing aluminum by carbothermic reduction of alumina wherein said carbothermic reduction yields an off-gas comprising carbon monoxide, aluminum vapor, and aluminum suboxide, said off-gas being directed to a reactor maintained at an elevated temperature, the improvement wherein for the purpose of reducing the reactor temperature, a gaseous or liquid hydrocarbon is supplied to the reactor, said hydrocarbon is cracked in the reactor to form carbon, and said carbon is reacted with the aluminum vapor and aluminum suboxide to form aluminum carbide.
Dependencies are inferred from the claim text.