Electrochemical Method and Apparatus For Removing Oxygen From a Compound or Metal

Abstract

A cathode comprising an oxygen-containing compound, or a metal containing dissolved oxygen, is arranged in contact with a melt comprising a hydroxide of an alkali metal. An inert anode, advantageously comprising nickel, is also arranged in contact with the melt and a potential is applied between the anode and the cathode such that oxygen is removed from the compound or the metal.

Description

[0001]The invention relates to a method and an apparatus for removing oxygen from a compound, comprising a metal and oxygen, or from a metal or alloy, by an electrolytic process.[0002]The electro-decomposition or electro-reduction of solid compounds is described in, for example, International Patent Application PCT / GB99 / 01781 and “Extraction of titanium from solid titanium dioxide in molten salts” by D. J. Fray and G. Z. Chen, TMS (The Minerals, Metals and Materials Society) 2004, pp. 9-17, which are incorporated herein by reference in their entirety. In this process, also known as the FFC process, a solid compound between a metal (which term is used in this document to include both metals and semi-metals) and another substance (for example, oxygen) is electrolytically reduced. A cathode comprising or contacting the solid compound is immersed in or contacted with a fused salt and a voltage is applied between the cathode and an anode, which also contacts the salt, such that the subst...

AI Technical Summary

Benefits of technology

The invention provides a method and apparatus for removing oxygen from a compound that contains metal and oxygen. The method involves using a cathode to arrange a melt containing a hydroxide of an alkali metal and an anode. A potential is applied between the cathode and the anode to remove oxygen from the solid compound. The melt can also contain other anions or cations, such as sodium iodide or sodium bromide, to decrease the melting point and allow for lower temperatures. The removal of oxygen can be accelerated by increasing temperature and reducing the potential between the cathode and the anode. The invention can also be used to produce intermetallic compounds or alloys by reducing oxygen from low stability metals or alloys. The apparatus includes an inert anode, which should be made from a material that forms an inert oxide layer, such as nickel or a nickel alloy.

Problems solved by technology

A problem arises, however, in providing an anode material which is sufficiently inert in a CaCl2-based melt.

At present, there is no suitable material that can be used as an inert anode in chloride melts such as calcium chloride and, therefore, a carbon anode is generally employed.

Furthermore, the carbon anode is consumed and the product of the electro-decomposition may become contaminated with carbon.

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