Method For Producing Metal

Abstract

A method for producing a metal by an electrolytic process using an yttria-containing porous ceramic body as a diaphragm is provided; the calcium formed by electrolysis cannot pass through the diaphragm, hence the back reaction can be effectively inhibited. Preferably, to be used is a diaphragm comprising a porous ceramic body having a purity of yttrium of 90 mass % or more (more preferably, 99% or more), a porosity of 1% or more and a pore diameter of 20 μm or less, and having a thickness of 0.05-50 mm and a metal halide is used as the electrolytic bath. The method can be utilized for producing metals such as calcium or rare earth elements, in particular. For example, when the method is applied to the production of calcium, metallic calcium can be produced with ease and at low cost without the need for enormous heat energy.

Description

TECHNICAL FIELD[0001]The present invention relates to a method for producing a metal by an electrolytic process, in particular to a method of producing a metal which can be applied to the production of such a metal as calcium or a rare earth element.BACKGROUND ART[0002]Metallic calcium is strong in reducing power and is a valuable metal usable as a reducing agent in producing other metals. Rare earth metals are used in various ways in a wide range of fields of industry, such as glasses (coloring agents), ceramics and, further, magnetic materials, nuclear materials, metallurgical additives, catalysts, etc.[0003]Among those metals, rare earth metals are currently produced by the steps of: extracting specific rare earth metals (to be produced) from a refined ore containing them by a solvent extracting process; converting them to oxides by an alkali precipitation process, for instance; and then reducing the oxides by a fused or molten salt electrolysis or metallothermic reduction proces...

AI Technical Summary

Benefits of technology

[0017]In a third embodiment of the invention, the porous ceramic body has a porosity of 1% or more so that it may function as a diaphragm while securing the conductivity of the bath. In a fourth embodiment of the invention, the diaphragm desirably has a thickness of 0.05-50 mm. Further, in a fifth embodiment of the invention, the porous ceramic body has a pore diameter of 20 μm or less so that the passage of metallic calcium through it may effectively be inhibited.

[0019]In an eighth embodiment of the invention, a molten calcium salt or a mixed salt containing calcium salt in a molten state is used as an electrolytic bath to make it possible to obtain metallic calcium or a molten salt containing metallic calcium by applying the relevant method for producing a metal (inclusive of any of the above-mentioned embodiments).

[0021]The method for producing a metal according to the invention is a method using an yttria-containing porous ceramic body as a diaphragm and can be utilized in the production of such a metal as calcium or a rare earth element and, in particular, is suited for the production of metallic calcium. When the method is applied to the production of calcium, for instance, metallic calcium can be produced with much ease and at low cost without consuming enormous heat energy to be needed in the prior art aluminum reduction method.

Problems solved by technology

As the results of these, they found that a porous ceramic body comprising yttria (Y2O3) as prepared by firing or sintering shows such a selective permeability that it allows the passage of calcium and chloride ions but does not allow the passage of metallic calcium.

Although yttria has a property such that it will not be reduced by even a metal having a strong reducing powder such as calcium, yttria has so far been regarded as being difficult to apply as a diaphragm from the viewpoint of strength and the like.

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