Molten Salt Electrolytic Cell and Process for Producing Metal Using the Same

Abstract

A molten salt electrolytic cell comprises a vessel filled with a molten salt bath, an anode immersed in the bath, and a cathode immersed in the bath, and the cathode is hollow.

Description

TECHNICAL FIELD[0001]The present invention relates to a molten salt electrolytic cell and relates to a process for producing metal using the same. Specifically, the present invention relates to a technique of molten salt electrolysis used for extraction of calcium chloride containing calcium that may be used as a reductant for producing titanium from titanium compounds.BACKGROUND ART[0002]Conventionally, sponge titanium is produced by the Kroll method, and various improvements have been made to reduce the costs of production. However, since the Kroll method is a batch process, efficiency may not be further improved.[0003]As a technique for improving the efficiency of production of titanium by the Kroll method, a technique has been suggested in which titanium oxides are reduced with calcium in a molten salt so as to produce titanium (for example, refer to WO99 / 064638). Moreover, in a technique that is similar to that in the above patent document, a method for refining titanium having...

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Benefits of technology

[0010]In view of the above circumstances, an object of the present invention is to provide an electrolytic cell for extraction of calcium chloride containing calcium used for reducing an oxide or chloride of titanium. Specifically, the present invention provides a molten salt electrolytic cell in which calcium chloride is efficiently extracted by molten salt electrolysis.

[0011]The inventors have performed research on a molten salt electrolytic cell in view of the above circumstances. As a result, the inventors found that calcium chloride can be efficiently extracted by hollowing out a cathode. Moreover, the inventors found that calcium chloride is more efficiently extracted and collected when an anode and a hollow cathode are immersed and are disposed in a molten salt bath and a fin member is arranged and is disposed on the surface of the cathode. That is, the calcium chloride containing calcium that is produced at the cathode is efficiently introduced into the hollow space of the cathode with minimum influence of the flow in the bath and difference in specific gravity with respect to the surroundings. Then, the calcium chloride is extracted through the hollow portion by a pressure reducing device provided outside. Thus, the inventors have completed the invention as described below.

[0016]According to the present invention, the cathode is hollow, or the cathode is hollow and is provided with a fin member by connecting and a through hole is provided directly above the connected portion. Therefore, the calcium or calcium chloride partially containing calcium is efficiently collected and is extracted to the outside before calcium that has precipitated on the surface of the cathode dissolves or diffuses into the entire calcium chloride bath. Moreover, according to the present invention, in addition to the above effects, the cathode is entirely immersed and is dispersed under the anode, whereby chlorine gas produced at the anode and calcium produced at the cathode will not recombine. As a result, current efficiency is improved.

Problems solved by technology

However, since the Kroll method is a batch process, efficiency may not be further improved.

However, calcium produced by molten salt electrolysis is difficult to separate as calcium itself, because calcium has a solubility for calcium chloride.

However, because carbon in the calcium carbide contaminates the calcium, this technique cannot be used for producing high purity titanium.

Thus, techniques that have been developed are inefficient in producing calcium chloride in which calcium is mixed or is dissolved (hereinafter simply referred to as “calcium chloride containing calcium”) by molten salt electrolyzing with calcium chloride.

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