US20090211916A1 - Method and apparatus for producing metal by electrolysis of molton salt - Google Patents
Method and apparatus for producing metal by electrolysis of molton salt Download PDFInfo
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- US20090211916A1 US20090211916A1 US11/631,364 US63136405A US2009211916A1 US 20090211916 A1 US20090211916 A1 US 20090211916A1 US 63136405 A US63136405 A US 63136405A US 2009211916 A1 US2009211916 A1 US 2009211916A1
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
- C25C7/007—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells of cells comprising at least a movable electrode
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
- C25C7/06—Operating or servicing
- C25C7/08—Separating of deposited metals from the cathode
Definitions
- the present invention relates to the recovery of metal from a chloride thereof, and in particular, relates to a method and an apparatus for producing metal by electrolysis of molten salts containing metal chlorides.
- titanium metal which is a simple substance
- Kroll method in which titanium tetrachloride is reduced by molten magnesium to obtain sponge titanium
- various kinds of improvements have been made to reduce the cost of production.
- the Kroll method is a batch process in which a set of operations is repeated noncontinuously, there is a limitation to its efficiency.
- the present invention has been completed in view of the above situation, and an object of the present invention is to provide a method for production of metal by molten-salt electrolysis, in which a metal used for reducing, such as an oxide or chloride of titanium metal, is recovered in a solid state and at low cost.
- a metal used for reducing such as an oxide or chloride of titanium metal
- a method for production of metal by molten-salt electrolysis of the present invention has a step of filling an electrolysis vessel having a positive electrode and negative electrode with a metal chloride, a step of heating to fuse the metal chloride to make an electrolytic bath, and a step of electrolyzing the electrolytic bath to deposit metal in a solid state on the negative electrode.
- a metal can be deposited on the negative electrode in a solid state, which is a state having low solubility in the molten salt, and it can be recovered. Furthermore, the recovery of the metal can be performed at low cost.
- An apparatus for production of metal by molten-salt electrolysis of the present invention has an electrolysis vessel having a positive electrode and a negative electrode therein and a metal chloride filled in the vessel, the metal chloride is heated and molten to make an electrolytic bath, and the electrolytic bath is electrolyzed to deposit metal in a solid state on the negative electrode. Furthermore, in the apparatus, the electrolytic bath is divided into an electrolysis chamber and a dissolution chamber by a dividing wall, the positive electrode is arranged in the electrolysis chamber, and the negative electrode is arranged to enable orbital movement in a circle through the electrolysis chamber and the dissolution chamber. Metal which is deposited on the negative electrode in the electrolysis chamber is recovered in the dissolution chamber.
- electrolysis of metal chloride is promoted and the metal is deposited on the negative electrode while the negative electrode is passing through the electrolysis chamber, and the metal deposited can be recovered during the negative electrode passing through the dissolution chamber. Furthermore, since the negative electrode revolves and passes through the electrolysis chamber and dissolution chamber regularly, deposition and recovery of the metal can be automatically and efficiently performed.
- FIG. 1 is a conceptual diagram showing the method for production of calcium metal in an embodiment of the present invention.
- FIG. 2A is a conceptual diagram showing the method for production of calcium metal in another embodiment of the present invention
- FIG. 2B is a conceptual diagram showing a scraping device on the negative electrode in the case in which FIG. 2A is seen from direction A.
- FIG. 3A is a conceptual diagram showing the method for production of calcium metal in another embodiment of the present invention
- FIG. 3B is a conceptual diagram in the case in which FIG. 3A is seen from direction A
- FIG. 3C is a conceptual diagram in the case in which FIG. 3A is seen from direction B.
- FIGS. 1 to 3 show embodiments of an apparatus to perform the present invention. Next, a case in which the electrolytic bath is one of calcium chloride and the metal generated is calcium metal, is explained.
- reference numeral 1 is an electrolysis vessel, and electrolytic bath 2 comprising calcium chloride is filled therein and heated to a temperature not less than the melting point of calcium chloride by a heating means, which is not shown, to keep the electrolytic bath in a molten state.
- Reference numeral 3 is a positive electrode and reference numeral 4 is a negative electrode, and they are immersed in the electrolytic bath 2 .
- the positive and negative electrodes 3 and 4 are connected to a direct current power supply, which is not shown, and electrolysis of the electrolytic bath is started. Chloride ions in the electrolytic bath 2 are attracted to the positive electrode 3 and emit electrons to generate chlorine gas which is lost from the system. Calcium ions are attracted to the negative electrode and receive electrons to generate calcium metal 5 which is deposited on the surface of negative electrode 4 .
- the present invention can be efficiently performed even in the cases in which the temperature of the electrolytic bath 2 is above or below the melting point of calcium metal 5 (845° C.).
- the temperature of the electrolytic bath 2 is below the melting point of calcium metal, calcium metal 5 can be deposited in a solid state on the surface of the negative electrode 4 .
- the temperature of the electrolytic bath 2 is above the melting point of calcium metal 5 , calcium metal 5 can be deposited in a solid state on the surface of the negative electrode 4 in the case in which a cooling structure is installed in the negative electrode 4 .
- the negative electrode 4 After a certain amount of calcium metal 5 is deposited on the negative electrode 4 , the negative electrode 4 is taken out of the electrolytic bath 2 and is immersed in a recovery vessel 7 having molten salt 6 for which the temperature is maintained above the melting point of calcium metal 5 (845° C.). The calcium metal 5 deposited on the negative electrode 4 is partially dissolved in the molten salt 6 held in the recovery vessel 7 , and the rest floats up from the negative electrode 4 to be condensed around the surface of the liquid. The condensed part is collected and recovered. In this case, since evaporation loss becomes larger as the temperature is increased, the temperature is practically set at not more than 900° C.
- Calcium can be dissolved, floated and recovered in a liquid state as explained above, and in addition, it can be cooled to not more than the melting point of calcium metal (845° C.) as long as the molten salt 6 is not solidified. By performing such a cooling operation, calcium metal 5 floats in a solid state, and it can be efficiently recovered. Since the melting point of calcium chloride is about 780° C. and the melting point of calcium metal is about 845° C., by decreasing the temperature of the recovery vessel 7 to about 800° C., calcium metal 5 molten in the molten salt 6 can be recovered in a solid state.
- the negative electrode 4 after separating and recovering the calcium metal 5 deposited, can be transferred from the recovery vessel 7 to the electrolysis vessel 1 to perform molten-salt electrolysis again. By repeating the above-mentioned set of operations, calcium metal can be efficiently recovered.
- the calcium metal 5 generated in the recovery vessel 7 in this way can be used in the reduction of titanium tetrachloride using molten salt.
- calcium metal is not recovered in the recovery vessel 7 leaving the concentration of calcium metal in the molten salt 6 high, and the molten salt containing calcium can be used in the reduction reaction of titanium tetrachloride.
- Chlorine gas 8 generated on the positive electrode 3 in the electrolysis vessel 1 can be separately recovered and can be reused in a chlorination reaction of titanium ore. Alternatively, it can be used for other purposes.
- a material of the positive electrode 3 As a material of the positive electrode 3 , a material having an electrical conductivity which does not dissolve in the electrolytic bath and does not react with chlorine gas, is desirable. As such a material, carbon is desirable.
- the negative electrode 4 can be constructed by an electrical conductive material, for example, carbon steel, stainless steel, copper, aluminum or the like can be used.
- the negative electrode 4 desirably has a structure in which a cooling medium can be circulated therein. The structure can promote deposition of calcium metal on the negative electrode 4 .
- the molten salt 6 in the recovery vessel 7 arbitrarily selected one can be used, and in particular, calcium chloride is desirable. Since calcium chloride is a by-product of molten-salt electrolysis of titanium chloride and calcium metal, if the molten salt 6 is calcium chloride, it will be unnecessary to remove calcium chloride when condensed calcium metal is used in a molten-salt electrolysis process for titanium chloride. In addition, that is because after the molten-salt electrolysis process for titanium chloride, the molten salt 6 can be reused with calcium chloride which is a by-product of this process in the electrolysis vessel 1 .
- the melting point of the electrolytic bath can be decreased by adding potassium chloride to calcium chloride forming the electrolytic bath 2 .
- the amount of potassium chloride added to calcium chloride is desirably in a range from 20 to 80 wt %. By adding potassium chloride in this range, even if the temperature of the electrolytic bath 2 is decreased below the melting point of calcium metal by the temperature between 150° C. and 250° C., reliable operation can be performed without solidification of the electrolytic bath.
- the temperature of the electrolytic bath 2 can be arbitrarily controlled within the target temperature range by using a heating burner having a cooling function, which is not shown, immersed in the electrolytic bath.
- a heating burner having a cooling function which is not shown, immersed in the electrolytic bath.
- another means can be employed to control the temperature of the electrolytic bath 2 .
- FIG. 2 shows another embodiment of the present invention.
- Electrolytic bath 2 comprising calcium chloride is filled in the electrolysis vessel 1 of FIG. 2A , is heated to a temperature not less than the melting point of calcium chloride by a heating means, which is not shown, and is held in a molten state.
- the positive electrode 3 and the negative electrode 4 having cylindrical shape are immersed in the electrolytic bath 2 .
- This negative electrode 4 can be constructed so as to be rotatable, and the scraping device 9 is arranged neighboring to an edge of a side surface of the cylindrical negative electrode 4 .
- FIG. 2B shows a conceptual diagram of the negative electrode 4 and the scraping device 9 seen from the direction A. As shown in the figure, by rotating the negative electrode, calcium metal 5 deposited on the surface of the negative electrode is efficiently scraped by the scraping device 9 .
- Solid calcium metal 5 scraped from the negative electrode 4 floats up to the surface of the electrolytic bath 2 since the density of calcium metal is lower than that of calcium chloride.
- the calcium metal 5 which floated to the surface of the electrolytic bath 2 is recovered from the electrolytic bath 2 .
- the solid calcium metal recovered from the electrolytic bath 2 is used as a reducing agent for titanium oxide in molten-salt electrolysis.
- a basket having a net structure can be arranged around the scraping device 9 .
- solid metal deposited can be efficiently recovered.
- the dividing wall 10 be arranged around the surface of electrolytic bath 2 . Calcium metal deposited on the negative electrode 4 is scraped and then floats and diffuses to the bath surface. Finally, calcium metal can reach the positive electrode 3 , and it has a tendency to react oppositely with the chlorine gas generated on the positive electrode 3 . However, by arranging the dividing wall 10 , diffusion of floating calcium metal can be prevented, and the back reaction can be effectively suppressed.
- the temperature of the electrolytic bath around the scraping device 9 can be maintained, to a limited extent, at a temperature not less than the melting point of calcium metal, by immersing and arranging a heater near the scraping device 9 .
- calcium metal scraped from the negative electrode 4 can be recovered in a molten state.
- the calcium metal in a molten state is partially dissolved in calcium chloride, and the rest floats up in the electrolytic bath 2 . Therefore, calcium chloride having condensed calcium metal is floating around the surface of the electrolytic bath 2 via the dividing wall 10 .
- By extracting floating calcium chloride having condensed calcium metal for example, it can be used in reduction reactions for titanium tetrachloride.
- FIGS. 3A to 3C show another embodiment of the present invention.
- FIG. 3B is a conceptual diagram of FIG. 3A seen from direction A
- FIG. 3C is a conceptual diagram of FIG. 3A seen from direction B.
- Electrolytic bath 2 comprising calcium chloride is filled in the electrolysis vessel 1 of FIG. 3 , and the electrolytic bath 2 is heated to a temperature not less than the melting point of calcium chloride so as to be maintained in a molten state by a heating means, which is not shown. Furthermore, the positive electrode 3 and the negative electrode 4 are immersed and arranged in the electrolytic bath 2 .
- the electrolysis vessel 1 is divided into the electrolysis chamber 1 a in which the positive electrode 3 is immersed and the dissolution chamber 1 b is isolated by the dividing wall 10 arranged around the surface of the electrolytic bath 2 . It should be noted that only the upper part of the electrolytic bath 2 is divided by the dividing wall 10 , and the lower part thereof is unified. As shown in FIG. 3C , plural negative electrodes 4 are arranged to enable orbital movement in a circle through the electrolysis chamber 1 a and dissolution chamber 1 b . These negative electrodes 4 can be revolved in a circle through the electrolysis chamber and dissolution chamber by passing through a sliced channel arranged at a part of the dividing wall 10 .
- Heating function and cooling function are provided to the negative electrode 4 . That is, a flow passage in which a heater and a cooling medium can be circulated is arranged inside the negative electrode 4 . In this way, the temperature of the negative electrode 4 can be arbitrarily controlled from a temperature not more than the melting point of calcium metal 5 to a temperature not less than the melting point of calcium metal 5 .
- the temperature of the negative electrode 4 is maintained at a temperature not more than the melting point of calcium metal to deposit the calcium metal on the surface of the negative electrode in a solid state.
- the temperature of the negative electrode 4 is maintained at a temperature not less than the melting point of calcium metal to fuse the calcium metal deposited.
- Calcium metal 5 is molten and released from the negative electrode 4 and is partially dissolved in calcium chloride, and the rest floats up in the electrolytic bath, to form a calcium metal condensed layer.
- the calcium metal condensed layer formed at the bath surface of the dissolution chamber of the electrolytic bath 2 is extracted at appropriate times, and for example, it can be used as a reducing agent for titanium oxide in molten-salt electrolysis.
- Molten-salt electrolysis of calcium chloride was performed by using both the electrolysis vessel and the recovery vessel shown in FIG. 1 .
- Calcium metal is deposited on the negative electrode by controlling the temperature of the electrolytic bath comprising calcium chloride at 800 ⁇ 5° C. As a result, calcium metal having 85% of the weight of the theoretical weight calculated from electricity applied between the positive electrode and negative electrode was recovered.
Abstract
A process for production of a metal includes a step of filling a metal chloride in an electrolysis vessel having positive and negative electrodes, a step of heating and fusing the metal chloride to make an electrolytic bath, and a step of electrolyzing the electrolytic bath to deposit metal on the negative electrode in a solid state. In addition, in an apparatus for production of a metal in which a metal chloride is filled in an electrolysis vessel having positive and negative electrodes, the metal chloride is heated and molten to make an electrolytic bath and the electrolytic bath is electrolyzed to deposit the metal on the negative electrode in a solid state, the electrolytic bath is divided into an electrolysis chamber and a dissolution chamber by a dividing wall, the positive electrode is arranged in the electrolysis chamber, the negative electrode is arranged to enable orbital movement in a circle through the electrolysis chamber and dissolution chamber, and the metal deposited on the negative electrode in the electrolysis chamber is separated and recovered in the dissolution chamber.
Description
- The present invention relates to the recovery of metal from a chloride thereof, and in particular, relates to a method and an apparatus for producing metal by electrolysis of molten salts containing metal chlorides.
- Conventionally, titanium metal, which is a simple substance, is produced by the Kroll method in which titanium tetrachloride is reduced by molten magnesium to obtain sponge titanium, and various kinds of improvements have been made to reduce the cost of production. However, since the Kroll method is a batch process in which a set of operations is repeated noncontinuously, there is a limitation to its efficiency.
- To resolve such a situation, a method in which titanium oxide is reduced by calcium metal in molten salt to obtain titanium metal directly (see WO99/064638 and Japanese Unexamined Patent Application Publication No. 2003-129268), one in which an EMR method in which a reducing agent containing an active metal such as calcium or an active metal alloy is prepared, and one in which a titanium compound is reduced by electrons emitted from the reducing agent to yield titanium metal (see Japanese Unexamined Patent Application Publication No. 2003-306725) have been proposed. In these methods, calcium oxide, which is a by-product of the electrolytic reaction, is dissolved in calcium chloride, and molten-salt electrolysis is performed to recover and reuse calcium metal. However, since the calcium metal generated during the electrolytic reaction is in a liquid state and has high solubility in calcium chloride, it dissolves easily in the calcium chloride. There has been no disclosure of a technique to recover calcium metal in a solid state alone.
- Furthermore, a technique in which a molten salt electrolysis is performed at a temperature lower than the conventional electrolysis using a complex molten salt having a melting point lower than that of calcium metal to deposit calcium metal on a negative electrode in a solid state is disclosed (see U.S. Pat. No. 3,226,311). However, in this production method, it is necessary to prepare the complex molten salt specially, and the cost is considerable.
- As explained above, there is a problem in that it is difficult to recover an active metal such as calcium metal alone, and there is a problem in that the cost is high even if the recovery is possible.
- The present invention has been completed in view of the above situation, and an object of the present invention is to provide a method for production of metal by molten-salt electrolysis, in which a metal used for reducing, such as an oxide or chloride of titanium metal, is recovered in a solid state and at low cost.
- That is, a method for production of metal by molten-salt electrolysis of the present invention has a step of filling an electrolysis vessel having a positive electrode and negative electrode with a metal chloride, a step of heating to fuse the metal chloride to make an electrolytic bath, and a step of electrolyzing the electrolytic bath to deposit metal in a solid state on the negative electrode.
- By the present invention, a metal can be deposited on the negative electrode in a solid state, which is a state having low solubility in the molten salt, and it can be recovered. Furthermore, the recovery of the metal can be performed at low cost.
- An apparatus for production of metal by molten-salt electrolysis of the present invention has an electrolysis vessel having a positive electrode and a negative electrode therein and a metal chloride filled in the vessel, the metal chloride is heated and molten to make an electrolytic bath, and the electrolytic bath is electrolyzed to deposit metal in a solid state on the negative electrode. Furthermore, in the apparatus, the electrolytic bath is divided into an electrolysis chamber and a dissolution chamber by a dividing wall, the positive electrode is arranged in the electrolysis chamber, and the negative electrode is arranged to enable orbital movement in a circle through the electrolysis chamber and the dissolution chamber. Metal which is deposited on the negative electrode in the electrolysis chamber is recovered in the dissolution chamber.
- By the present invention, electrolysis of metal chloride is promoted and the metal is deposited on the negative electrode while the negative electrode is passing through the electrolysis chamber, and the metal deposited can be recovered during the negative electrode passing through the dissolution chamber. Furthermore, since the negative electrode revolves and passes through the electrolysis chamber and dissolution chamber regularly, deposition and recovery of the metal can be automatically and efficiently performed.
-
FIG. 1 is a conceptual diagram showing the method for production of calcium metal in an embodiment of the present invention. -
FIG. 2A is a conceptual diagram showing the method for production of calcium metal in another embodiment of the present invention, andFIG. 2B is a conceptual diagram showing a scraping device on the negative electrode in the case in whichFIG. 2A is seen from direction A. -
FIG. 3A is a conceptual diagram showing the method for production of calcium metal in another embodiment of the present invention, andFIG. 3B is a conceptual diagram in the case in whichFIG. 3A is seen from direction A, andFIG. 3C is a conceptual diagram in the case in whichFIG. 3A is seen from direction B. -
- 1 . . . Electrolysis vessel,
- 1 a . . . Electrolysis chamber,
- 1 b . . . Dissolution chamber,
- 2 . . . Electrolytic bath,
- 3 . . . Positive electrode,
- 4 . . . Negative electrode,
- 5 . . . Metal (calcium),
- 6 . . . Molten salt,
- 7 . . . Recovery vessel,
- 8 . . . Chlorine gas,
- 9 . . . Scraping device,
- 10 . . . Dividing wall
- Embodiments of the present invention are explained below with reference to the drawings.
FIGS. 1 to 3 show embodiments of an apparatus to perform the present invention. Next, a case in which the electrolytic bath is one of calcium chloride and the metal generated is calcium metal, is explained. - In
FIG. 1 ,reference numeral 1 is an electrolysis vessel, andelectrolytic bath 2 comprising calcium chloride is filled therein and heated to a temperature not less than the melting point of calcium chloride by a heating means, which is not shown, to keep the electrolytic bath in a molten state.Reference numeral 3 is a positive electrode andreference numeral 4 is a negative electrode, and they are immersed in theelectrolytic bath 2. - The positive and
negative electrodes electrolytic bath 2 are attracted to thepositive electrode 3 and emit electrons to generate chlorine gas which is lost from the system. Calcium ions are attracted to the negative electrode and receive electrons to generatecalcium metal 5 which is deposited on the surface ofnegative electrode 4. - The present invention can be efficiently performed even in the cases in which the temperature of the
electrolytic bath 2 is above or below the melting point of calcium metal 5 (845° C.). In particular, if the temperature of theelectrolytic bath 2 is below the melting point of calcium metal,calcium metal 5 can be deposited in a solid state on the surface of thenegative electrode 4. On the other hand, even if the temperature of theelectrolytic bath 2 is above the melting point ofcalcium metal 5,calcium metal 5 can be deposited in a solid state on the surface of thenegative electrode 4 in the case in which a cooling structure is installed in thenegative electrode 4. - In both cases, since
calcium metal 5 generated in the electrolytic reaction is deposited in a solid state, the solubility of thesolid calcium metal 5 in calcium chloride contacting therewith is extremely small. Therefore, calcium metal can be recovered at high yield. - After a certain amount of
calcium metal 5 is deposited on thenegative electrode 4, thenegative electrode 4 is taken out of theelectrolytic bath 2 and is immersed in arecovery vessel 7 havingmolten salt 6 for which the temperature is maintained above the melting point of calcium metal 5 (845° C.). Thecalcium metal 5 deposited on thenegative electrode 4 is partially dissolved in themolten salt 6 held in therecovery vessel 7, and the rest floats up from thenegative electrode 4 to be condensed around the surface of the liquid. The condensed part is collected and recovered. In this case, since evaporation loss becomes larger as the temperature is increased, the temperature is practically set at not more than 900° C. - Calcium can be dissolved, floated and recovered in a liquid state as explained above, and in addition, it can be cooled to not more than the melting point of calcium metal (845° C.) as long as the
molten salt 6 is not solidified. By performing such a cooling operation,calcium metal 5 floats in a solid state, and it can be efficiently recovered. Since the melting point of calcium chloride is about 780° C. and the melting point of calcium metal is about 845° C., by decreasing the temperature of therecovery vessel 7 to about 800° C.,calcium metal 5 molten in themolten salt 6 can be recovered in a solid state. - The
negative electrode 4, after separating and recovering thecalcium metal 5 deposited, can be transferred from therecovery vessel 7 to theelectrolysis vessel 1 to perform molten-salt electrolysis again. By repeating the above-mentioned set of operations, calcium metal can be efficiently recovered. Thecalcium metal 5 generated in therecovery vessel 7 in this way can be used in the reduction of titanium tetrachloride using molten salt. - Alternatively, calcium metal is not recovered in the
recovery vessel 7 leaving the concentration of calcium metal in themolten salt 6 high, and the molten salt containing calcium can be used in the reduction reaction of titanium tetrachloride. -
Chlorine gas 8 generated on thepositive electrode 3 in theelectrolysis vessel 1 can be separately recovered and can be reused in a chlorination reaction of titanium ore. Alternatively, it can be used for other purposes. - As a material of the
positive electrode 3, a material having an electrical conductivity which does not dissolve in the electrolytic bath and does not react with chlorine gas, is desirable. As such a material, carbon is desirable. - The
negative electrode 4 can be constructed by an electrical conductive material, for example, carbon steel, stainless steel, copper, aluminum or the like can be used. Thenegative electrode 4 desirably has a structure in which a cooling medium can be circulated therein. The structure can promote deposition of calcium metal on thenegative electrode 4. - As the
molten salt 6 in therecovery vessel 7, arbitrarily selected one can be used, and in particular, calcium chloride is desirable. Since calcium chloride is a by-product of molten-salt electrolysis of titanium chloride and calcium metal, if themolten salt 6 is calcium chloride, it will be unnecessary to remove calcium chloride when condensed calcium metal is used in a molten-salt electrolysis process for titanium chloride. In addition, that is because after the molten-salt electrolysis process for titanium chloride, themolten salt 6 can be reused with calcium chloride which is a by-product of this process in theelectrolysis vessel 1. - The melting point of the electrolytic bath can be decreased by adding potassium chloride to calcium chloride forming the
electrolytic bath 2. The amount of potassium chloride added to calcium chloride is desirably in a range from 20 to 80 wt %. By adding potassium chloride in this range, even if the temperature of theelectrolytic bath 2 is decreased below the melting point of calcium metal by the temperature between 150° C. and 250° C., reliable operation can be performed without solidification of the electrolytic bath. - The temperature of the
electrolytic bath 2 can be arbitrarily controlled within the target temperature range by using a heating burner having a cooling function, which is not shown, immersed in the electrolytic bath. Alternatively, another means can be employed to control the temperature of theelectrolytic bath 2. -
FIG. 2 shows another embodiment of the present invention.Electrolytic bath 2 comprising calcium chloride is filled in theelectrolysis vessel 1 ofFIG. 2A , is heated to a temperature not less than the melting point of calcium chloride by a heating means, which is not shown, and is held in a molten state. Furthermore, thepositive electrode 3 and thenegative electrode 4 having cylindrical shape are immersed in theelectrolytic bath 2. Thisnegative electrode 4 can be constructed so as to be rotatable, and thescraping device 9 is arranged neighboring to an edge of a side surface of the cylindricalnegative electrode 4.FIG. 2B shows a conceptual diagram of thenegative electrode 4 and thescraping device 9 seen from the direction A. As shown in the figure, by rotating the negative electrode,calcium metal 5 deposited on the surface of the negative electrode is efficiently scraped by thescraping device 9. -
Solid calcium metal 5 scraped from thenegative electrode 4 floats up to the surface of theelectrolytic bath 2 since the density of calcium metal is lower than that of calcium chloride. Thecalcium metal 5 which floated to the surface of theelectrolytic bath 2 is recovered from theelectrolytic bath 2. The solid calcium metal recovered from theelectrolytic bath 2 is used as a reducing agent for titanium oxide in molten-salt electrolysis. - In this case, a basket having a net structure can be arranged around the
scraping device 9. By taking the basket out of the electrolytic bath at appropriate times, solid metal deposited can be efficiently recovered. - It is desirable that the dividing
wall 10 be arranged around the surface ofelectrolytic bath 2. Calcium metal deposited on thenegative electrode 4 is scraped and then floats and diffuses to the bath surface. Finally, calcium metal can reach thepositive electrode 3, and it has a tendency to react oppositely with the chlorine gas generated on thepositive electrode 3. However, by arranging the dividingwall 10, diffusion of floating calcium metal can be prevented, and the back reaction can be effectively suppressed. - The temperature of the electrolytic bath around the
scraping device 9 can be maintained, to a limited extent, at a temperature not less than the melting point of calcium metal, by immersing and arranging a heater near thescraping device 9. In this way, calcium metal scraped from thenegative electrode 4 can be recovered in a molten state. The calcium metal in a molten state is partially dissolved in calcium chloride, and the rest floats up in theelectrolytic bath 2. Therefore, calcium chloride having condensed calcium metal is floating around the surface of theelectrolytic bath 2 via the dividingwall 10. By extracting floating calcium chloride having condensed calcium metal, for example, it can be used in reduction reactions for titanium tetrachloride. -
FIGS. 3A to 3C show another embodiment of the present invention.FIG. 3B is a conceptual diagram ofFIG. 3A seen from direction A, andFIG. 3C is a conceptual diagram ofFIG. 3A seen from direction B.Electrolytic bath 2 comprising calcium chloride is filled in theelectrolysis vessel 1 ofFIG. 3 , and theelectrolytic bath 2 is heated to a temperature not less than the melting point of calcium chloride so as to be maintained in a molten state by a heating means, which is not shown. Furthermore, thepositive electrode 3 and thenegative electrode 4 are immersed and arranged in theelectrolytic bath 2. Theelectrolysis vessel 1 is divided into theelectrolysis chamber 1 a in which thepositive electrode 3 is immersed and thedissolution chamber 1 b is isolated by the dividingwall 10 arranged around the surface of theelectrolytic bath 2. It should be noted that only the upper part of theelectrolytic bath 2 is divided by the dividingwall 10, and the lower part thereof is unified. As shown inFIG. 3C , pluralnegative electrodes 4 are arranged to enable orbital movement in a circle through theelectrolysis chamber 1 a anddissolution chamber 1 b. Thesenegative electrodes 4 can be revolved in a circle through the electrolysis chamber and dissolution chamber by passing through a sliced channel arranged at a part of the dividingwall 10. - Heating function and cooling function are provided to the
negative electrode 4. That is, a flow passage in which a heater and a cooling medium can be circulated is arranged inside thenegative electrode 4. In this way, the temperature of thenegative electrode 4 can be arbitrarily controlled from a temperature not more than the melting point ofcalcium metal 5 to a temperature not less than the melting point ofcalcium metal 5. - In the construction of apparatus explained above, when the
negative electrode 4 is in the electrolysis chamber side, the temperature of thenegative electrode 4 is maintained at a temperature not more than the melting point of calcium metal to deposit the calcium metal on the surface of the negative electrode in a solid state. On the other hand, when the negative electrode revolves and reaches to the dissolution chamber side, the temperature of thenegative electrode 4 is maintained at a temperature not less than the melting point of calcium metal to fuse the calcium metal deposited.Calcium metal 5 is molten and released from thenegative electrode 4 and is partially dissolved in calcium chloride, and the rest floats up in the electrolytic bath, to form a calcium metal condensed layer. The calcium metal condensed layer formed at the bath surface of the dissolution chamber of theelectrolytic bath 2 is extracted at appropriate times, and for example, it can be used as a reducing agent for titanium oxide in molten-salt electrolysis. - In this way, by controlling the temperature of the negative electrode from a temperature below the melting point of calcium metal to a temperature above the melting point of calcium metal depending on the position of the
negative electrode 4 revolving inside theelectrolytic bath 2, calcium metal can be efficiently recovered. - Molten-salt electrolysis of calcium chloride was performed by using both the electrolysis vessel and the recovery vessel shown in
FIG. 1 . Calcium metal is deposited on the negative electrode by controlling the temperature of the electrolytic bath comprising calcium chloride at 800±5° C. As a result, calcium metal having 85% of the weight of the theoretical weight calculated from electricity applied between the positive electrode and negative electrode was recovered. - Using the apparatus shown in
FIG. 2 and using calcium chloride as an electrolytic bath, molten-salt electrolysis was performed to deposit calcium metal continuously on the negative electrode. The calcium metal was scraped by the scraping device to recover it in a solid state. The amount of calcium metal produced per unit time was about twice as much as that of Example 1. - Using the apparatus shown in
FIG. 3 and using calcium chloride as an electrolytic bath, molten-salt electrolysis was performed to deposit calcium metal continuously on the negative electrode. The calcium metal in a molten state partially containing the electrolytic bath was recovered. The amount of calcium metal produced per unit time was about twice as much as that of Example 2. - As explained thus far, calcium metal can be efficiently produced by electrolysis of calcium chloride by the present invention.
Claims (15)
1-10. (canceled)
11. A process for production of a metal by molten-salt electrolysis, the process comprising:
a step of filling metal chloride in an electrolysis vessel having a positive electrode and a negative electrode;
a step of heating and fusing the metal chloride to make an electrolytic bath; and
a step of electrolyzing the electrolytic bath to deposit metal on the negative electrode in a solid state.
12. The process for production of a metal by molten-salt electrolysis according to claim 11 ,
wherein the temperature of the electrolytic bath used in the molten-salt electrolysis is maintained at not more than the melting point of the metal.
13. The process for production of a metal by molten-salt electrolysis according to claim 11 ,
wherein the temperature of the electrolytic bath used in the molten-salt electrolysis is maintained at not less than the melting point of the metal, and at the same time the temperature of the negative electrode is maintained at not more than the melting point of the metal.
14. The process for production of a metal by molten-salt electrolysis according to claim 11 ,
wherein the metal in a solid state deposited on the negative electrode is scraped by a mechanical means.
15. The process for production of a metal by molten-salt electrolysis according to claim 12 ,
wherein the metal in a solid state deposited on the negative electrode is scraped by a mechanical means.
16. The process for production of a metal by molten-salt electrolysis according to claim 13 ,
wherein the metal in a solid state deposited on the negative electrode is scraped by a mechanical means.
17. The process for production of a metal by molten-salt electrolysis according to claim 11 ,
wherein the negative electrode on which the metal in a solid state is deposited is immersed in metal chloride filled in a recovery vessel maintained at a temperature not less than the melting point of the metal, so as to recover the metal.
18. The process for production of a metal by molten-salt electrolysis according to claim 12 ,
wherein the negative electrode on which the metal in a solid state is deposited is immersed in metal chloride filled in a recovery vessel maintained at a temperature not less than the melting point of the metal, so as to recover the metal.
19. The process for production of a metal by molten-salt electrolysis according to claim 13 ,
wherein the negative electrode on which the metal in a solid state is deposited is immersed in metal chloride filled in a recovery vessel maintained at a temperature not less than the melting point of the metal, so as to recover the metal.
20. The process for production of a metal by molten-salt electrolysis according to claim 11 ,
wherein the electrolytic bath is divided into an electrolysis chamber and a dissolution chamber by a dividing wall, the positive electrode is arranged in the electrolysis chamber, and the negative electrode is arranged to enable orbital movement in circle through the electrolysis chamber and dissolution chamber,
wherein the temperature of the negative electrode is maintained at a temperature not more than the melting point of the metal when the negative electrode passes through the electrolysis chamber and the temperature of the negative electrode is maintained at a temperature not less than the melting point of the metal when the negative electrode passes through the dissolution chamber.
21. The process for production of a metal by molten-salt electrolysis according to claim 20 ,
wherein the negative electrode comprises plural electrodes and the electrodes are arranged on the orbital path.
22. The process for production of a metal by molten-salt electrolysis according to claim 11 ,
wherein the metal chloride is calcium chloride and the metal is calcium metal.
23. An apparatus for production of a metal by molten-salt electrolysis, in which metal chloride is filled in an electrolysis vessel having a positive electrode and a negative electrode, the metal chloride is heated and molten to make an electrolytic bath, and the electrolytic bath is electrolyzed to deposit metal on the negative electrode in a solid state,
wherein the electrolytic bath is divided into an electrolysis chamber and a dissolution chamber by a dividing wall, the positive electrode is arranged in the electrolysis chamber, the negative electrode is arranged to enable orbital movement in a circle through the electrolysis chamber and dissolution chamber, and
wherein the metal deposited on the negative electrode while the electrode is in the electrolysis chamber is separated and recovered while the electrode is in the dissolution chamber.
24. The apparatus for production of metal by molten-salt electrolysis according to claim 23 ,
wherein the negative electrode comprises plural electrodes and the electrodes are arranged on the orbital path.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2004-192905 | 2004-06-30 | ||
JP2004192905 | 2004-06-30 | ||
PCT/JP2005/011747 WO2006003864A1 (en) | 2004-06-30 | 2005-06-27 | Method and apparatus for producing metal by electrolysis of molten salt |
Publications (1)
Publication Number | Publication Date |
---|---|
US20090211916A1 true US20090211916A1 (en) | 2009-08-27 |
Family
ID=35782673
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/631,364 Abandoned US20090211916A1 (en) | 2004-06-30 | 2005-06-27 | Method and apparatus for producing metal by electrolysis of molton salt |
Country Status (5)
Country | Link |
---|---|
US (1) | US20090211916A1 (en) |
EP (1) | EP1785509A4 (en) |
JP (1) | JP4658053B2 (en) |
AU (1) | AU2005258596A1 (en) |
WO (1) | WO2006003864A1 (en) |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2123798A4 (en) * | 2007-02-19 | 2010-03-17 | Toho Titanium Co Ltd | Apparatus for producing metal by molten salt electrolysis, and process for producing metal using the apparatus |
WO2009008121A1 (en) * | 2007-07-12 | 2009-01-15 | Toho Titanium Co., Ltd. | Process for producing high-purity metallic calcium, process for producing metallic titanium with use of the calcium, and high-purity metallic calcium producing apparatus |
JP4934012B2 (en) * | 2007-12-11 | 2012-05-16 | 東邦チタニウム株式会社 | Method for producing metallic calcium |
JP5138465B2 (en) * | 2008-05-27 | 2013-02-06 | 東邦チタニウム株式会社 | Method and apparatus for producing metallic calcium |
EA036662B1 (en) | 2016-03-25 | 2020-12-04 | АЛКОА ЮЭсЭй КОРП. | Electrode configurations for electrolytic cells and related methods |
CN107385474B (en) * | 2017-08-04 | 2018-10-12 | 中南大学 | A kind of chlorination calcium molten salt electrolysis calcium electrolyte and the electrolytic method using the electrolyte |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2344859A (en) * | 1941-02-07 | 1944-03-21 | Abraham L Fox | Method of producing calcium boride |
US2960397A (en) * | 1958-09-03 | 1960-11-15 | Dow Chemical Co | Separation of calcium metal from contaminants |
US3043756A (en) * | 1958-07-31 | 1962-07-10 | Dow Chemical Co | Calcium metal production |
US3226311A (en) * | 1959-05-13 | 1965-12-28 | Solvay | Process of producing calcium by electrolysis |
US5089094A (en) * | 1989-03-16 | 1992-02-18 | Osaka Titanium Company Limited | Process for the electrolytic production of magnesium |
US6712952B1 (en) * | 1998-06-05 | 2004-03-30 | Cambridge Univ. Technical Services, Ltd. | Removal of substances from metal and semi-metal compounds |
US20040237711A1 (en) * | 2001-10-17 | 2004-12-02 | Katsutoshi Ono | Method and apparatus for smelting titanium metal |
Family Cites Families (4)
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JPS5443811A (en) | 1977-09-16 | 1979-04-06 | Asahi Glass Co Ltd | Production of metallic lithium |
JPH1053888A (en) * | 1996-08-12 | 1998-02-24 | Central Res Inst Of Electric Power Ind | Method for recovering metallic material to be recovered of fused salt electrolytic device and device therefor |
JP2002129250A (en) | 2000-10-30 | 2002-05-09 | Katsutoshi Ono | Method for producing metallic titanium |
NO318164B1 (en) * | 2002-08-23 | 2005-02-07 | Norsk Hydro As | Method for electrolytic production of aluminum metal from an electrolyte and use of the same. |
-
2005
- 2005-06-27 JP JP2006528672A patent/JP4658053B2/en not_active Expired - Fee Related
- 2005-06-27 EP EP05765165A patent/EP1785509A4/en not_active Withdrawn
- 2005-06-27 AU AU2005258596A patent/AU2005258596A1/en not_active Abandoned
- 2005-06-27 US US11/631,364 patent/US20090211916A1/en not_active Abandoned
- 2005-06-27 WO PCT/JP2005/011747 patent/WO2006003864A1/en active Application Filing
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2344859A (en) * | 1941-02-07 | 1944-03-21 | Abraham L Fox | Method of producing calcium boride |
US3043756A (en) * | 1958-07-31 | 1962-07-10 | Dow Chemical Co | Calcium metal production |
US2960397A (en) * | 1958-09-03 | 1960-11-15 | Dow Chemical Co | Separation of calcium metal from contaminants |
US3226311A (en) * | 1959-05-13 | 1965-12-28 | Solvay | Process of producing calcium by electrolysis |
US5089094A (en) * | 1989-03-16 | 1992-02-18 | Osaka Titanium Company Limited | Process for the electrolytic production of magnesium |
US6712952B1 (en) * | 1998-06-05 | 2004-03-30 | Cambridge Univ. Technical Services, Ltd. | Removal of substances from metal and semi-metal compounds |
US20040159559A1 (en) * | 1998-06-05 | 2004-08-19 | Fray Derek John | Removal of oxygen from metal oxides and solid solutions by electrolysis in a fused salt |
US20040237711A1 (en) * | 2001-10-17 | 2004-12-02 | Katsutoshi Ono | Method and apparatus for smelting titanium metal |
Also Published As
Publication number | Publication date |
---|---|
EP1785509A4 (en) | 2008-06-25 |
JP4658053B2 (en) | 2011-03-23 |
AU2005258596A1 (en) | 2006-01-12 |
EP1785509A1 (en) | 2007-05-16 |
JPWO2006003864A1 (en) | 2008-04-17 |
WO2006003864A1 (en) | 2006-01-12 |
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Owner name: TOHO TITANIUM CO., LTD., JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:YAMAGUCHI, MASANORI;ONO, YUICHI;KOSEMURA, SUSUMU;AND OTHERS;REEL/FRAME:018753/0520 Effective date: 20061115 |
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