U.S. patent application number 11/576887 was filed with the patent office on 2008-04-03 for method and apparatus for producing metal by molten-salt electrolysis.
This patent application is currently assigned to TOHO TITANIUM CO., LTD.. Invention is credited to Masahiko Hori, Susumu Kosemura, Eiji Nishimura, Tadashi Ogasawara, Yuichi Ono, Toru Uenishi, Makoto Yamaguchi, Masanori Yamaguchi.
Application Number | 20080078679 11/576887 |
Document ID | / |
Family ID | 36148273 |
Filed Date | 2008-04-03 |
United States Patent
Application |
20080078679 |
Kind Code |
A1 |
Yamaguchi; Masanori ; et
al. |
April 3, 2008 |
Method and Apparatus for Producing Metal by Molten-Salt
Electrolysis
Abstract
A method for production of metal by molten-salt electrolysis of
the present invention is a method for production of metal by
molten-salt electrolysis which is performed by filling a molten
salt of calcium chloride in an electrolysis vessel having a anode
and a cathode, one of the anode or cathode is arranged surrounding
the other electrode, the cathode has at least one hole
communicating the inner area surrounded by the cathode with the
outer area, and the molten salt flows through the communicating
holes from one area including the anode (the inner area or outer
area) to the other area.
Inventors: |
Yamaguchi; Masanori;
(Kanagawa, JP) ; Ono; Yuichi; (Kanagawa, JP)
; Kosemura; Susumu; (Kanagawa, JP) ; Nishimura;
Eiji; (Kanagawa, JP) ; Ogasawara; Tadashi;
(Hyogo, JP) ; Yamaguchi; Makoto; (Hyogo, JP)
; Hori; Masahiko; (Hyogo, JP) ; Uenishi; Toru;
(Hyogo, JP) |
Correspondence
Address: |
ANTONELLI, TERRY, STOUT & KRAUS, LLP
1300 NORTH SEVENTEENTH STREET, SUITE 1800
ARLINGTON
VA
22209-3873
US
|
Assignee: |
TOHO TITANIUM CO., LTD.
Kanagawa
JP
SUMITOMO TITANIUM CORPORATION
Hyogo
JP
|
Family ID: |
36148273 |
Appl. No.: |
11/576887 |
Filed: |
October 5, 2005 |
PCT Filed: |
October 5, 2005 |
PCT NO: |
PCT/JP05/18449 |
371 Date: |
April 9, 2007 |
Current U.S.
Class: |
205/399 ;
204/212; 204/272; 205/402 |
Current CPC
Class: |
C22B 34/129 20130101;
C25C 7/025 20130101; C25C 3/28 20130101; C25C 3/02 20130101 |
Class at
Publication: |
205/399 ;
204/212; 204/272; 205/402 |
International
Class: |
C25C 3/02 20060101
C25C003/02; C25C 3/28 20060101 C25C003/28; C25C 7/00 20060101
C25C007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 12, 2004 |
JP |
2004-297865 |
Claims
1. A process for production of a metal by molten-salt electrolysis,
the process comprising a step of filling calcium chloride in an
electrolysis vessel having a anode and a cathode; wherein one of
the negative or anode is arranged surrounding the other electrode,
the cathode has at least one hole which communicates an inner area
surrounded by the cathode and an outer area, and the molten salt is
flowed from one of the inner or outer area having the anode therein
to the other area through the communicating hole.
2. The process for production of a metal by molten-salt
electrolysis according to claim 1, wherein the cathode is arranged
surrounding the anode, the cathode has at least one hole which
communicates an inner area surrounded by the cathode and an outer
area, and the molten salt is flowed from the inner area to the
outer area through the communicating hole.
3. The process for production of a metal by molten-salt
electrolysis according to claim 2, wherein calcium chloride is
supplied to the inner area.
4. The process for production of a metal by molten-salt
electrolysis according to claim 2, wherein the molten salt
containing calcium metal generated at the cathode is extracted from
the outer area.
5. The process for production of a metal by molten-salt
electrolysis according to claim 1, wherein the electrolysis vessel
is made of carbon to enable functioning as the anode, a hollow
cylindrical cathode is arranged in the electrolysis vessel, the
cathode has at least one hole which communicates the inner area of
the cathode and the outer area, and the molten salt is flowed from
the outer area to the inner area through the communicating
hole.
6. The process for production of a metal by molten-salt
electrolysis according to claim 5, wherein inert gas is supplied
from the bottom part of the inner area of the cathode.
7. The process for production of a metal by molten-salt
electrolysis according to claim 1, wherein a finned cylindrical
cathode having plural communicating holes all inclined at a
predetermined angle from the normal line direction of the side
surface of the cylinder, is used as the hollow cylindrical cathode,
the finned cylindrical cathode is rotated to flow the molten salt
from the inner area to the outer area, or from the outer area to
the inner area.
8. The process for production of a metal by molten-salt
electrolysis according to claim 5, wherein calcium chloride is
supplied to the outer area.
9. The process for production of a metal by molten-salt
electrolysis according to claim 5, wherein the molten salt
containing calcium metal generated at the cathode is extracted from
the inner area.
10. The process for production of a metal by molten-salt
electrolysis according to claim 1, wherein the metal is recovered
as a mixed material with the molten salt or recovered as a molten
material.
11. The process for production of a metal by molten-salt
electrolysis according to claim 1, wherein the molten salt consists
of calcium chloride, sodium chloride, barium chloride, and lithium
chloride.
12. The process for production of a metal by molten-salt
electrolysis according to claim 1, wherein a titanium tetrachloride
supplying pipe is arranged in the inner area in which the metal is
generated by the molten-salt electrolysis, and titanium metal is
generated by supplying titanium tetrachloride in a gas state
through the titanium tetrachloride supplying pipe.
13. The process for production of a metal by molten-salt
electrolysis according to claim 12, wherein an upward flow of the
electrolysis bath is generated in the inner area by an upward flow
of the titanium tetrachloride in a gas state, and the metal
generated is recovered at the electrolysis bath.
14. The process for production of a metal by molten-salt
electrolysis according to claim 12, wherein the finned cylindrical
cathode is used as the cathode, the titanium tetrachloride
supplying pipe is arranged at the lower end of the inner area, a
downward flow of the electrolysis bath is generated in the inner
area by rotating the finned cylindrical cathode, and titanium
tetrachloride is supplied to be contacted against the downward
flow, to generate metal.
15. The process for production of a metal by molten-salt
electrolysis according to claim 12, wherein the titanium
tetrachloride supplying pipe is arranged at a lower end of the
inner area and the agitating fin is arranged at the inner area, and
a downward flow of the electrolysis bath is generated in the inner
area by rotating the agitating fin and titanium tetrachloride is
supplied to contact the downward flow to generate titanium
metal.
16. The process for production of a metal by molten-salt
electrolysis according to claim 1, wherein the metal is calcium or
titanium.
17. An apparatus for production of a metal by molten-salt
electrolysis comprising: an electrolysis vessel and a anode and a
cathode in the electrolysis vessel; wherein one of the negative or
anode is arranged surrounding the other electrode, the cathode has
at least one hole which communicates an inner area surrounded by
the cathode and an outer area, the molten salt of calcium chloride
is supplied to one of the two divided areas in which the anode is
included therein, the molten salt of calcium chloride is flowed to
the other area through the communicating hole, the molten salt of
calcium chloride containing calcium metal generated at the cathode
is extracted from the other area.
18. The apparatus for production of a metal by molten-salt
electrolysis according to claim 17, wherein the cathode is arranged
so as to be rotatable.
19. The apparatus for production of a metal by molten-salt
electrolysis according to claim 17, wherein an agitating fin to
enable the molten salt flowing from the inner area to the outer
area or from the outer area to the inner area of the cathode, is
arranged at the lower end of the inside of the cathode.
20. The apparatus for production of a metal by molten-salt
electrolysis according to claim 17, wherein the metal is calcium
metal or titanium metal.
Description
TECHNICAL FIELD
[0001] The present invention relates to the production of metal
from a chloride thereof, and in particular, relates to a method for
producing calcium metal by molten-salt electrolysis and to a method
for producing metal, including a method for producing titanium
metal, by using the calcium metal, and relates to an apparatus
therefor.
BACKGROUND ART
[0002] 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 overcome this, 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.
[0003] Furthermore, a technique has been disclosed in which a
molten salt electrolysis is performed at a temperature lower than
that in the conventional electrolysis using a complex molten salt
having a melting point lower than that of calcium metal to deposit
calcium metal on a cathode in a solid state (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.
[0004] In addition, in any of the methods explained above, the
calcium metal generated in the molten-salt electrolysis has a
tendency to reverse react with chlorine gas generated in the
electrolysis reaction to again form calcium chloride. Thus,
production efficiency is deteriorated.
[0005] 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. As a result, the cost of producing titanium
is increased.
DISCLOSURE OF THE INVENTION
[0006] The present invention has been completed in view of the
above circumstances, and an object of the present invention is to
provide a method for production of metal by molten-salt
electrolysis, in which metal calcium used for reducing, such as an
oxide or chloride of titanium metal, is produced, and in which
titanium metal can be obtained by using this metal calcium
efficiently at low cost.
[0007] The method for production of metal by molten-salt
electrolysis of the present invention is a method for production of
metal by molten-salt electrolysis which is performed by filling
molten salt of calcium chloride in an electrolysis vessel having a
anode and a cathode, one electrode (the anode or cathode) is
arranged surrounding the other electrode, the cathode has at least
one hole communicating the inner area surrounded by the cathode
with the outer area, and the molten salt flows through the
communicating holes from one area including the anode (the inner
area or outer area) to the other area.
[0008] By the present invention, since one electrode of the
positive or cathode is surrounding the other electrode and the
molten salt flows from the area including the anode to the other
area through the communicating holes arranged on the cathode, the
calcium metal generated on the surface of the cathode during the
molten salt electrolysis always flows to the area not including the
anode, and the calcium metal is precipitated and accumulated at the
electrolysis bath surface of the area. Therefore, the back reaction
with chlorine gas generated on the surface of anode can be avoided,
and calcium metal can be produced at high efficiency.
[0009] Furthermore, the apparatus for production of metal by
molten-salt electrolysis is an apparatus for production of metal by
molten-salt electrolysis having a anode and a cathode in a
electrolysis vessel, one electrode of the cathode or anode being
arranged surrounding the other electrode, the cathode having at
least one hole communicating an inner area surrounded by the
cathode with an outer area, molten salt of calcium chloride being
supplied to the area including the anode, the molten salt of
calcium chloride flowing to the other area through the
communicating hole, and the molten salt of calcium chloride
containing calcium metal generated at the cathode is extracted from
the other area.
[0010] By this apparatus for production, as described above,
calcium metal generated on the surface of the cathode by the molten
salt electrolysis is always flowed to the area without the anode,
and the calcium metal is precipitated and accumulated at the
electrolysis bath surface of the area. Therefore, the calcium metal
does not reverse react with chlorine gas generated on the surface
of the anode, and the calcium metal can be produced at high
efficiency.
[0011] Furthermore, in the method for production of metal by
molten-salt electrolysis of the present invention, a titanium
tetrachloride supplying pipe is arranged in the inner area in which
calcium metal is generated by molten-salt electrolysis, and
titanium tetrachloride in the gas phase is supplied through the
titanium tetrachloride supplying pipe to generate titanium
metal.
[0012] By such a method for production, since titanium
tetrachloride is supplied to the calcium metal generated in the
inner area by molten-salt electrolysis, they are reacted with each
other to generate titanium metal. Therefore, it is not necessary
that calcium metal be once recovered and be sent to a titanium
producing process, and titanium metal can be obtained in the
production process of calcium metal.
[0013] By the present invention, the back reaction of calcium metal
and chlorine gas generated during the molten-salt electrolysis of
calcium chloride can be reduced, and calcium metal can be
efficiently produce at low cost. Furthermore, by directly supplying
titanium tetrachloride, titanium metal can also be obtained.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a conceptual cross sectional diagram showing a
production process for calcium metal by molten-salt electrolysis in
an embodiment of the present invention.
[0015] FIG. 2 is a conceptual cross sectional diagram showing a
production process for calcium metal by molten-salt electrolysis in
another embodiment of the present invention.
[0016] FIG. 3 is a conceptual cross sectional diagram showing a
production process for calcium metal by molten-salt electrolysis in
another embodiment of the present invention.
[0017] FIG. 4 is a conceptual cross sectional diagram showing a
production process for calcium metal by molten-salt electrolysis in
another embodiment of the present invention.
[0018] FIG. 5 is a conceptual cross sectional diagram showing a
production process for calcium metal by molten-salt electrolysis in
another embodiment of the present invention.
[0019] FIG. 6 is a conceptual cross sectional diagram showing a
production process for calcium metal by molten-salt electrolysis
and a production process of titanium metal in another embodiment of
the present invention.
[0020] FIG. 7 is a conceptual cross sectional diagram showing a
production process for calcium metal by molten-salt electrolysis
and a production process of titanium metal in another embodiment of
the present invention.
[0021] FIG. 8 is a conceptual cross sectional diagram showing a
production process for calcium metal by molten-salt electrolysis
and a production process of titanium metal in another embodiment of
the present invention.
[0022] FIG. 9 is a conceptual cross sectional diagram showing a
finned cylindrical cathode used in the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0023] Embodiments of the present invention are explained below
with reference to the drawings. The drawings show appropriate
examples of apparatus construction to practice the present
invention. FIG. 1 shows a conceptual cross sectional diagram of the
first embodiment of the present invention. Reference numeral 1 is
an electrolysis vessel, and an electrolysis bath 2 consisting of
calcium chloride (melting point 780.degree. C.) is filled in the
vessel. The electrolysis bath 2 is heated to a temperature above
the melting point of calcium chloride by a heater (not shown) to be
maintained in a molten state. Reference numeral 3 indicates a
anode. Reference numeral 4 indicates a cylindrical cathode, which
is arranged surrounding the anode 3. Plural communicating holes are
formed at a lower part of the cathode 4, and the molten salt can be
moved between the inner area and the outer area of the cathode.
Since the communicating holes are formed at the lower part of the
cathode, the upper part of the cathode can function as a division
wall.
[0024] Furthermore, a bath supplying pipe 6 is arranged at an inner
part of the cathode 4, and calcium chloride which is a raw material
of the molten-salt electrolysis is continuously supplied
therethrough. An extracting pipe 7 is arranged at an upper and
outer part of the cathode 4 to extract calcium metal.
[0025] Starting the electrolysis by connecting the anode 3 and
cathode n 4 to a direct current power supply, which is not shown,
calcium metal in a molten state is generated on an inner surface of
the cathode 4. Since the molten salt is continuously supplied
through the bath supplying pipe 6, the generated calcium metal is
flowed from the inside of the cathode 4 against the outside, and
the calcium metal is pushed out to the outside. The calcium metal 5
reaching the outside of the cathode 4 is partially dissolved in the
electrolyte bath and floats up, forming a precipitated layer of
calcium metal 5.
[0026] The molten calcium metal which is moved to the outside of
the cathode 4 and floats up, and the calcium chloride in which
calcium metal is precipitated, are continuously extracted by the
extracting pipe 7. The molten calcium metal and the calcium
chloride having precipitated calcium metal are both extracted and
can be used in a reduction reaction of titanium oxide or titanium
chloride using molten salt, for example.
[0027] On the other hand, chlorine gas is generated at the surface
of the anode 3 and is emitted out of the system. The chlorine gas
can be used in a chlorination reaction of titanium ore or the
like.
[0028] FIG. 2 shows a conceptual cross sectional diagram of the
second embodiment of the present invention. Reference numeral 1 is
an electrolysis vessel, and an electrolysis bath 2 consisting of
calcium chloride (melting point 780.degree. C.) is filled in the
vessel. The electrolysis bath 2 is heated to a temperature above
the melting point of calcium chloride by a heater, which is not
shown, so as to be maintained in a molten state. Reference numeral
3 indicates a anode which is unified with the electrolysis vessel.
Reference numeral 4 is a cylindrical cathode, and it is immersed at
the central part of the electrolysis vessel 1. Plural communicating
holes are formed at a lower part of the cathode 4, and the molten
salt can be moved between the outer area and the inner area of the
cathode. Since the communicating holes are formed at the lower part
of the cathode, an upper part of the cathode can function as a
division wall.
[0029] Furthermore, a bath supplying pipe 6 is arranged at an outer
part of the cathode 4, and calcium chloride which is a raw material
of the molten-salt electrolysis is continuously supplied
therethrough. An extracting pipe 7 is arranged at an upper and
inner part of the cathode 4 to extract calcium metal.
[0030] Starting the electrolysis by connecting the anode 3 and
cathode 4 to a direct current power supply, which is not shown,
calcium metal in a molten state is generated on an outer surface of
the cathode 4. Since the molten salt is continuously supplied
through the bath supplying pipe 6, the generated calcium metal is
flowed from the outside of the cathode 4 against the inside, and
the calcium metal is pushed into the inside. The calcium metal 5
reaching the inside of the cathode 4, is partially dissolved in the
electrolyte bath and floats up, forming a precipitated layer of
calcium metal 5.
[0031] The molten calcium metal which is moved to the inside of the
cathode 4 and floats up, and the calcium chloride in which calcium
metal is precipitated, are continuously extracted by the extracting
pipe 7. The molten calcium metal and the calcium chloride having
precipitated calcium metal are both extracted and can be used in a
reduction reaction of titanium oxide or titanium chloride using
molten salt, for example.
[0032] On the other hand, chlorine gas is generated at the surface
of the anode 3 and is emitted out of the system. The chlorine gas
can be used in a chlorination reaction of titanium ore or the
like.
[0033] FIG. 3 shows a conceptual cross sectional diagram of the
third favorable embodiment of the present invention. Explanations
of reference numerals 1 to 8 are omitted since they are similar to
those for FIG. 2. In FIG. 3, which is different from the case of
FIG. 2, inert gas is injected from the bottom part of the inner
area of the cathode 4 through an inert gas supplying pipe 9. A
gas-lift effect occurs by the injection of the inert gas, and
upward flow occurs in the inner area of the cathode 4. Accompanied
by this effect, a flow from the outer area to the inner area
occurs. As a result, calcium metal generated on the surface of the
cathode 4 can be moved into the inside the cathode in a short time,
and a loss by the back reaction with chlorine gas which is
generated in the outer area of the cathode can be reduced.
[0034] FIG. 4 shows a conceptual cross sectional diagram of the
fourth favorable embodiment of the present invention. Arrangement
of reference numerals 1 to 8 is omitted since they are similar to
those in FIG. 2. Differing from the above-mentioned embodiments, an
oblique communicating hole inclining in a vertical direction is
formed at a side wall of the cathode 4, as shown in FIG. 4. In
addition, as shown in FIG. 9, which is a conceptual cross sectional
diagram in which the cathode 4 is seen from above, the
communicating holes are inclined uniformly from the normal line
direction of the cylindrical electrode also in the horizontal
direction. Furthermore, the cathode 4 is arranged so as to be
rotatable. By rotating such a cathode 4, the molten salt can be
forcibly moved from the outer area of the cathode 4 to the inner
area. As a result, calcium metal generated on the outer surface of
the cathode 4 can be moved into the inner area of the cathode in a
short time, and a loss by the back reaction with chlorine gas which
is generated in the outer area of the cathode can be reduced.
[0035] FIG. 5 shows a conceptual cross sectional diagram of the
fifth favorable embodiment of the present invention. Explanation of
reference numerals 1 to 8 is omitted since they are similar to
those in FIG. 2. Differing from the above-mentioned embodiments, an
agitating fin 10 is arranged at the bottom part of the inner area
of the cathode 4. The agitating fin can be rotated via a driving
axis to form a flow of molten salt from the bottom to the upper
surface. As a result, calcium m 4 can be moved to the inner area of
the cathode in a short time, and a loss by the back reaction with
chlorine gas which is generated in the outer area of the cathode
can be reduced.
[0036] It should be noted that calcium metal generated on the outer
surface of the negative electrode 4 can be efficiently recovered by
combining the apparatuses shown in FIGS. 3 to 5, if necessary.
[0037] As explained above, by the present invention, since calcium
metal is continuously pushed out of the system soon after its
generation, the back reaction with chlorine gas can be prevented,
and the calcium metal can be efficiently produced. In particular,
by the second embodiment of the present invention, since the anode
and the electrolysis vessel are unified, the structure of the
apparatus can be favorably simplified. In addition, by the third,
fourth and fifth embodiments of the present invention, the back
reaction of calcium metal and chlorine gas can be efficiently
reduced.
[0038] During the molten-salt electrolysis of calcium chloride,
chlorine gas is generated at the anode. Therefore, it is required
to use a material having durability against the corrosion property
of chlorine gas, and in addition, having conductivity and not
having solubility in the electrolysis bath. As a material having
such properties, carbon is desirable.
[0039] On the other hand, the material of the negative electrode is
not limited in particular as long as the material has conductivity.
For example, carbon steel, stainless steel, or material such as
copper or the like can be used. From the viewpoint of processing
the negative electrode to have a cylindrical shape and forming
communicating holes, carbon steel having easy workability is
desirable.
[0040] The electrolysis bath consisting of calcium chloride is
required to be maintained at a temperature which is not lower than
the melting point of calcium metal (845.degree. C.). If the
temperature is lower than the melting point of the calcium metal,
calcium metal is generated in a solid state at the inner part of
the cathode and blocks up the communicating holes, and this
interferes with the flow-through of molten salt and calcium metal.
On the other hand, if the temperature is much greater than the
melting point of calcium metal, evaporation of the electrolysis
bath is promoted and solubility of calcium metal in calcium
chloride is increased. This is undesirable from the viewpoint of
the yield. A range not exceeding 100.degree. C. above the melting
point of calcium metal is desirable.
[0041] The temperature of the electrolysis bath can be controlled
by using a heating burner immersed in the electrolysis bath.
Furthermore, if the burner has a cooling function, this is
desirable because the temperature can be freely controlled in a
target range. In addition, temperature control can be performed by
another means of selection.
[0042] In the electrolysis bath, another salt can be added to
calcium chloride. For example, the melting point of the
electrolysis bath can be lowered by adding potassium chloride. By
lowering the melting point of the electrolysis bath in this way,
degrees of freedom of the electrolysis performing temperature are
increased and the cost required for heating can be reduced.
Potassium chloride added to calcium chloride is desirably in a
range from 20 to 80 mass %. By adding potassium chloride in such a
range, the melting point of the electrolysis bath can be lowered to
615 to 760.degree. C.
[0043] FIG. 6 shows a conceptual cross sectional diagram of the
sixth desirable embodiment of the present invention. Reference
numeral 1 is an electrolysis vessel, an electrolysis bath 2
consisting of calcium chloride is filled therein, and it is heated
to a temperature not less than the melting point of calcium
chloride by a heater, which is not shown, to be maintained in a
molten state. Reference numeral 3 indicates a anode unified with
the electrolysis vessel, and a cathode 4 having cylindrical shape
is arranged being immersed in a central part of the electrolysis
vessel 1. Since the upper and lower parts of the cathode 4 are
open, the molten salt can be moved between the outer area and inner
area of the cathode. Furthermore, a titanium tetrachloride
supplying pipe 11 is arranged in the inner area of the cathode
4.
[0044] The electrolysis is started by connecting the anode 3 and
cathode 4 to a direct current power supply, which is not shown, and
at the same time adding titanium tetrachloride 12 through the
titanium tetrachloride supplying pipe 11. Calcium metal in a molten
state is generated on an outer surface of the cathode 4 by the
starting of the electrolysis. At the same time, since titanium
tetrachloride 12 floats up in a bubbled state in the electrolysis
bath 2, upward-flow occurs in the electrolyte bath 2 by this
gas-lift effect, the electrolysis bath runs over from the inner
area to the outer area at the upper part of the cathode, and
downward-flow occurs in the outer area. In this way, flow in the
electrolysis bath occurs along the arrowed line shown in FIG. 6.
Calcium metal generated by the electrolysis floats up in the inner
area of the cathode and sinks down in the outer area along the
flow.
[0045] The above-mentioned upward-flow of the calcium metal
generated in the inner area of the cathode contacts and reacts with
the bubbles 12 of the titanium tetrachloride
(TiCl.sub.4+2Ca.fwdarw.2CaCl.sub.2+Ti), to generate titanium metal.
The titanium metal generated is carried to the upper or lower part
of the electrolysis bath by the flow of the bath, so as to be
recovered by a recovering device, which is not shown.
[0046] In this way, by the embodiment, it is not necessary that
calcium metal be recovered to be sent to a titanium producing
process. Calcium metal is generated and subsequently titanium metal
can be desirably obtained almost at the same time.
[0047] FIG. 7 shows a conceptual cross sectional diagram of the
seventh desirable embodiment of the present invention. Reference
numeral 1 is an electrolysis vessel, an electrolysis bath 2
consisting of calcium chloride is filled therein, and it is heated
at a temperature not less than the melting point of calcium
chloride by a heater, which is not shown, so as to be maintained in
a molten state. Reference numeral 3 indicates a anode unified with
the electrolysis vessel, a cathode 4 having a cylindrical shape is
arranged immersed in a central part of the electrolysis vessel 1.
The lower part of the cathode 4 is open, and a hole communicating
the outer part and inner part of the cathode is arranged at a side
surface of the cathode. These communicating holes are inclined
downward of the vertical direction. Furthermore, as shown in FIG.
9, the communicating holes of the cathode 4 are inclined from the
normal line direction of the cylindrica 4 is arranged so as to be
rotatable. A titanium tetrachloride supplying pipe 11 is arranged
at the lower part of the inner area of the cathode 4.
[0048] The electrolysis is started by connecting the anode 3 and
cathode 4 to a direct current power supply, which is not shown, and
at the same time rotating the cathode 4 and adding titanium
tetrachloride 12 through the titanium tetrachloride supplying pipe
11. Calcium metal in a molten state is generated on an outer
surface of the cathode 4 by the starting of the electrolysis. At
the same time, the electrolysis bath flows from the outer area of
the cathode 4 into the inner area by the rotation of the cathode 4,
and furthermore, since a downward flow occurs, calcium metal which
is generated is gathered in the inner area and flows downward.
Since titanium tetrachloride 12 floats up in bubbled state in the
electrolysis bath and contacts with this calcium metal flow, they
react to generate titanium metal. The titanium metal generated is
carried to the lower part of the electrolysis bath by the flow of
the bath so as to be recovered by a recovering device, which is not
shown.
[0049] In this way, in the embodiment, it is not necessary that
calcium metal be recovered and be sent to a titanium producing
process. Calcium metal is generated, and subsequently, titanium
metal can be desirably obtained almost at the same time.
Furthermore, since calcium metal is gathered in the inner part of
the cathode and is reacted with titanium tetrachloride, a back
reaction with chlorine gas can be desirably reduced.
[0050] FIG. 8 shows a conceptual cross sectional diagram of the
eighth desirable embodiment of the present invention. Reference
numeral 1 is an electrolysis vessel, an electrolysis bath 2
consisting of calcium chloride is filled therein, and it is heated
to a temperature not less than the melting point of calcium
chloride by a heater, which is not shown, to be maintained in a
molten state. Reference numeral 3 is a anode which is unified with
the electrolysis vessel, and a cathode 4 having cylindrical shape
is arranged being immersed in a central part of the electrolysis
vessel 1. The lower part of the cathode 4 is open, and a hole
communicating the outer part and inner part of the cathode is
arranged at a side surface of the cathode. A titanium tetrachloride
supplying pipe 11 is arranged at the lower part of the inner area
of the cathode 4. An agitating fin 10 is rotatably arranged at the
inner area of the cathode 4.
[0051] The electrolysis is started by connecting the anode 3 and
cathode 4 to a direct current power supply, which is not shown, and
at the same time rotating the agitating fin 10 and adding titanium
tetrachloride 12 through the titanium tetrachloride supplying pipe
11. Calcium metal in a molten state is generated on an outer
surface of the cathode 4 by the starting of the electrolysis. At
the same time, the electrolysis bath flows from the outer area of
the cathode 4 into the inner area by the rotation of the agitating
fin 10, and furthermore, since a downward flow occurs, calcium
metal which is generated is gathered in the inner area and flows
downward. Since titanium tetrachloride 12 floats up in bubbled
state in the electrolysis bath and contacts with this calcium metal
flow, they react to generate titanium metal. The titanium metal
generated is carried to the lower part of the electrolysis bath by
the flow of the bath, so as to be recovered by a recovering device,
which is not shown.
[0052] In this way, also by this embodiment, it is not necessary
that calcium metal be recovered, washed, and be sent to a titanium
producing process. Calcium metal is generated, and subsequently
titanium metal can be desirably obtained almost at the same time.
Furthermore, since calcium metal is gathered in the inner part of
the cathode and is reacted with titanium tetrachloride, the back
reaction with chlorine gas can be desirably reduced.
EXAMPLES
[0053] Using the electrolysis vessel shown in FIG. 1, electrolysis
of a molten salt of calcium chloride was performed. The temperature
of the electrolysis bath consisting of calcium chloride was
maintained at 850.+-.5.degree. C., and the temperature of the
circular cathode 4 was also maintained at 850.+-.5.degree. C., and
they were not particularly being cooled.
[0054] Molten calcium chloride which is a raw material was
continuously supplied to the inside the cathode through the bath
supplying pipe 6, and at the same time, the precipitated layer of
calcium metal was extracted to the outside of the system through
the extracting pipe immersed in the outside the cathode. Calcium
metal extracted out of the system was used in a reduction reaction
of titanium oxide. On the other hand, chlorine gas generated at the
anode was used in a chlorination reaction of titanium ore. Calcium
metal was produced corresponding to 80% of theoretical weight
calculated from the amount of electricity applied to the cathode
and anode.
[0055] By the present invention, calcium metal can be efficiently
produced by the electrolysis of calcium chloride. Furthermore, the
calcium metal can be used in the production of titanium metal,
without recovery.
* * * * *