Inert alloy anode used for aluminum electrolysis and preparation method therefor

Abstract

An inert alloy anode for aluminum electrolysis contains Fe and Cu as primary components and further contains Sn; addition of the metal Sn contributes to formation of an oxide film with strong oxidization resistance and stable structure on the surface of the inert alloy anode and to improvement of the corrosion resistance of the anode; on this basis, the inert alloy anode further contains Ni, Al and Y, addition of the metal Al can prevent the primary metal components from being oxidized, and addition of the metal Y can control alloy to present a desired crystal form in the preparation process to achieve oxidization resistance.

Description

FIELD OF THE INVENTION[0001]The present invention relates to an inert alloy anode for aluminum electrolysis and a preparing method thereof, belonging to the field of aluminum electrolysis industry.BACKGROUND OF THE INVENTION[0002]Aluminum electrolysis refers to acquisition of aluminum by alumina electrolysis. In the prior art, a traditional Hall-Heroult molten salt aluminum electrolysis process is typically adopted for aluminum electrolysis, this process is featured by use of a cryolite-alumina molten salt electrolysis method in which cryolite Na3AlF6 fluoride salt melt is taken as flux, Al2O3 is dissolved in the fluoride salt, a carbon body is taken as an anode, aluminum liquid is taken as a cathode, and electrolytic aluminum is obtained by performing electrochemical reaction at the anode and cathode of the electrolytic cell at a high temperature ranging from 940° C. to 960° C. after a strong direct current is introduced. In the traditional aluminum electrolysis process, a carbon a...

AI Technical Summary

Benefits of technology

The present invention provides an inert alloy anode for aluminum electrolysis that is low cost, low power consumption, and has high electric conductivity. The inert alloy anode contains Fe, Cu, and Sn as primary components, and has an oxide film with high resistance to corrosion and low power consumption. The inert alloy anode has low overvoltage, low impurity content, and high purity of the final product aluminum. The inert alloy anode is stable and has high resistance to corrosion and low power consumption. The inert alloy anode is prepared by a specific method that ensures high purity and stability. The inert alloy anode has high melting point, low specific resistivity, and low overvoltage, reducing power consumption and improving the purity of the aluminum product.

Problems solved by technology

In the traditional aluminum electrolysis process, a carbon anode is ceaselessly consumed in the electrolysis process, thus constant replacement for the carbon anode is required; moreover, carbon dioxide, carbon monoxide, toxic fluorine hydride and other waste gases are continuously generated at the anode during alumina electrolysis, emission of these gases into environment will be harmful to environment and health of human and livestock, so that the waste gases generated by aluminum electrolysis need to be purified before emission, which accordingly increases the investment cost of the alumina electrolysis production process.

In the above art, the anode material with metal ceramic as the matrix, though hardly reacting with electrolyte, is large in resistance and high in overvoltage, which results in large power consumption of the process and high cost in the process of aluminum electrolysis; furthermore, the anode material with metal ceramic as the matrix has poor thermal shock resistance and consequently is liable to brittlement during use; and in addition, the processability in use of the anode made from the above materials is poor just because the anode material having the metal ceramic matrix is liable to brittlement, as a result, the anode in any shape cannot be obtained.

However, a large amount of expensive metal materials are used in preparation of the alloy anode in the above art to result in high cost of the anode material, and thus this alloy anode fails to meet the demand on industrial cost; moreover, the alloy anode prepared from the above metal components is low in electric conductivity and high in overvoltage, so that the power consumption of the process is increased, thus the alloy anode cannot meet the needs of the aluminum electrolysis process.

The oxide film on the surface of the alloy anode in the above art has low oxidization resistance and is further liable to oxidization reaction to generate products that are likely to be corroded by electrolyte, and the oxide film with low stability is liable to fall off the anode electrode in the electrolysis process; after the previous oxide film is corroded or falls off, the material of the alloy anode exposed to the surface will create a new oxide film by reaction with oxygen, such replacement between new and old oxide films results in continuous consumption and poor corrosion resistance of the anode material as well as short service life of electrodes; furthermore, the corroded or falling oxide film enters into liquid aluminum in the electrolysis process of alumina to degrade the purity of the final product aluminum, as a result, the manufactured aluminum product cannot meet the demand of national standards and accordingly cannot be directly used as a finished product.