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Method using single furnace carbothermic reduction with temperature control within the furnace

a technology of carbothermic reduction and furnace, which is applied in the direction of electric furnaces, furnace types, furnaces, etc., can solve the problems of increasing process costs, affecting the efficiency of the furnace, so as to achieve the effect of reducing the temperature within the furnace and simple method of producing lower carbon containing aluminum

Inactive Publication Date: 2006-03-02
ARCONIC INC +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0008] In step (b), arc heating using retractable, at least one vertical top electrodes are preferably used to provide slag. In step (d), addition of Al2O3 at this stage, very importantly, lowers the temperature within the furnace and changes the slag composition transferring a substantial amount of C from aluminum to the slag. This provides a very simple method to produce lower carbon containing aluminum, where only one furnace or reactor is used in the process.

Problems solved by technology

This however would seem to be difficult in operation and would appear to cause excessive vaporization.
In the carbothermic process, the use of dual reaction zones or a plurality of furnaces, adds expense to the process, and unnecessary complication.

Method used

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  • Method using single furnace carbothermic reduction with temperature control within the furnace
  • Method using single furnace carbothermic reduction with temperature control within the furnace
  • Method using single furnace carbothermic reduction with temperature control within the furnace

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Embodiment Construction

[0012]FIG. 1 is a simplified illustration of one embodiment of a carbotherimc reaction process to produce Al and, recover A1, Al2O and CO in the off-gases as Al4C3, Al2O3 and slag and passes this material to the smelting furnace. In FIG. 1, gas flows are shown as dashed lines and flows of solids and molten substances are shown as solid lines.

[0013] In FIG. 1, the off-gas from a carbothermic smelting furnace here, for simplicity, comprising a first stage 1 and possibly a second stage 2 is forwarded via conduits 3 and 4 to an enclosed off-gas reactor 5 operating at a temperature of about 1600° C. to 2050° C. depending on the type reactor. There could be more than one such reactor, for example, one for stage one smelter 1 and one for stage two smelter 2. The reactor 5 could be a counter-current moving bed reactor or a fluid bed or a series of fluid beds. The Al-components of the off-gas entering the reactor 5 react with the carbon to form Al4C3, Al2O3 and Al4C3—Al2O3 slag material. Co...

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Abstract

A start-up process of making aluminum using a single carbothermic reactor / furnace (11) having a single hollow reactor compartment with bottom resistance heating electrodes (16) (13) in the side of the reactor, involves adding Al2O3 and C (carbon) for start-up and melting the mixture to provide a (Al2O3—Al4C3) slag having a temperature between about 1875° C. and 2000° C.; and then adding Al4C3 to the slag and raising the temperature of the furnace (11) to form a top Al phase with 6 to 8 wt % C (21) and a bottom slag phase (22); and then adding Al2O3 is added to the Al—C / slag (21, 22) to produce an Al2O3 rich slag lower the reactant temperature and produce a decarbonization reaction (step 30) providing a top Al phase with less than 5 wt % C (23) which is then tapped after step (40). The remaining slag is the starting material.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a method of producing low carbon aluminum in a single reactor compartment carbothermic furnace with control to lower or raise the temperature of reactants within the interior of the reactor compartment. BACKGROUND OF THE INVENTION [0002] The direct carbothermic reduction of alumina has been described in U.S. Pat. No. 2,974,032 (Grunert et al.) and U.S. Pat. No. 6,440,193 B 1 (Johansen et al.) as well as in Proceedings 6th Conference on Molten Slags Fluxes and Salts, Edited by S. Seetharaman and D. Sichen “Carbothermic Aluminum”, K. Johansen, J. Aune, M. Bruno and A. Schei, Stockholm, Sweden-Helsinki Finland, Jun. 12-17, 2002. It has long been recognized that the overall reaction: Al2O3+3C=2Al+3CO  (1) takes place, or can be made to take place, generally in steps such as: 2Al2O3+9C=Al4C3+6CO (vapor)  (2) Al4C3+Al2O3=6Al+3CO (vapor)  (3) Al2O3+2C=Al2O (vapor)+2CO (vapor)  (4) Al2O3+4Al=3Al2O (vapor)  (5), and Al=Al (vapor...

Claims

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Application Information

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IPC IPC(8): C22B4/02
CPCC22B4/02C22B21/02C22B5/10
Inventor FRUEHAN, RICHARD J.
Owner ARCONIC INC