| 摘要 |
A metallic aluminium electrowinning anode structure having an iron-based alloy outer part with an active anode surface which is essentially metallic and free of any ceramic compounds of metals from the metallic is disclosed. The metallic anode structure can be covered with a temporary protection medium, e.g. a protective layer that prevents ceramic-forming reactions at the metallic anode surface and is separable before or upon immersion into the electrolyte. Also disclosed is a method of conditioning a metallic anode structure for producing aluminium in a molten electrolyte containing dissolved alumina, the metallic anode structure having initially an iron-based alloy outer part with an active anode surface which is essentially metallic and free of any ceramic compounds, in particular oxides and fluorides, of metals from the metallic anode structure, the method comprising the steps of: (a) covering the essentially metallic active surface free of said ceramic compound with a temporary protective layer which is substantially impermeable to any species reactable with the active surface to substantially prevent the active surface from reacting with any reactable species, in particular oxygen and fluorine species, until immersion into a molten electrolyte containing oxygen ions; (b) immersing into the molten electrolyte the metallic anode structure with its essentially metallic active surface free of said ceramic compounds, the temporary protective layer being removed prior to immersion into the molten electrolyte or by contact with the molten electrolyte; and (c) polarising the immersed metallic anode structure to form thereon a dense and coherent integral iron-based oxide layer which is electrochemically active for the oxidation of oxygen ions and which inhibits diffusion of oxygen towards the metallic anode structure.
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