JP6636737B2 - Magnesium reduction furnace - Google Patents

Description

  The present invention relates to a magnesium reduction furnace using sunlight suitable for reduction of magnesium oxide.

  The present inventors have developed a magnesium fuel cell as an emergency cell and have put it into practical use (see Patent Document 1). A magnesium fuel cell is a cell that uses magnesium and air (oxygen) as fuel.

  At the negative electrode of the magnesium fuel cell, magnesium (Mg) is oxidized to magnesium oxide (MgO). If this magnesium oxide is reduced, it can be used again as a negative electrode material of a magnesium fuel cell.

  Conventionally, magnesium has been refined by reducing magnesium oxide derived from minerals by a thermal reduction method such as an electrolytic method or a pigeon method. In the Pigeon method, a refining method using coal as a heat source is performed.

Since the pigeon method uses coal as a heat source, it emits a large amount of carbon dioxide (CO ₂ ), which is not preferable for the environment. Therefore, reduction furnaces for reducing magnesium using a solar furnace using sunlight as a heat source have been developed, and are disclosed in Patent Literature 2 and Patent Literature 3.

JP 2012-234799 A JP 2014-133917 A JP 2014-133918 A

  However, in a conventional solar furnace, in a briquette made of magnesium oxide and a reducing agent accommodated in a retort of a reaction vessel, temperature unevenness sometimes occurs in heating of the briquette by the solar furnace. In that case, magnesium was evaporated from a part of the briquette, and magnesium vapor was sometimes deposited on the cooled inner surface of the heat-resistant glass of the retort.

  In this case, since the magnesium vapor adheres to the inner surface of the glass and fogging occurs, the light transmittance of the retort deteriorates. In addition, when the briquette becomes larger than a certain size, a temperature difference occurs in the briquette, and the magnesium vapor generated partially may be solidified at the upper part of the briquette, that is, at the exit of the crucible. In this case, since the flow path near the exit of the crucible is clogged and the reduction reaction is deteriorated, the reduction reaction does not proceed smoothly.

  Furthermore, if the weather becomes cloudy in the middle of a day, the reduction efficiency will be reduced in a large retort that reduces the amount by one day, and the light applied to the briquette will be converted into heat and the temperature will exceed 1200 ° C. However, there is a problem that heat is radiated to the outside of the retort by radiation, and energy efficiency is reduced.

  In view of the above, an object of the present invention is to provide a magnesium reduction furnace capable of sequentially reducing magnesium oxide in a plurality of retorts for a predetermined time with a simple configuration.

  The magnesium reduction furnace of the present invention includes a storage unit that stores a briquette containing a magnesium oxide and a reducing agent, and a recovery unit that recovers the precipitated magnesium by depositing magnesium evaporated from the briquette by cooling. A plurality of retorts, a light-collecting unit that collects sunlight on briquettes in one of the plurality of retorts, and in a state where the plurality of retorts are placed, the sunlight collected by the light-collecting unit is And a stage driven to irradiate one of the plurality of retorts.

In the above configuration, a plurality of retorts may be circumferentially arranged on the stage, and the sunlight collected by the light collection unit may be sequentially irradiated by driving the stage.
The magnesium reduction furnace of the present invention preferably includes a driving unit for driving the stage and a control unit for controlling the driving unit.
The retort preferably includes a first retort portion including a double tube serving as a storage portion, and a second retort portion including a recovery portion. The first retort portion preferably has an inner tube portion and an outer tube portion, a vacuum is applied between the inner tube portion and the outer tube portion, and a crucible is accommodated inside the inner tube portion. Briquettes may be accommodated in the crucible.
The outer tube preferably includes an incident window into which sunlight enters and a reflecting mirror. The reflecting mirror may be formed on the surface of the outer tube portion, and preferably comprises a metal film formed on the surface of the outer tube portion facing the crucible.

  According to the present invention, briquettes are separately stored in each of the plurality of retort storage sections for subdivision, and the briquettes in one retort are irradiated with sunlight condensed by the light collection unit, and the collection section is formed. By cooling, it is possible to provide a magnesium reduction furnace capable of efficiently reducing magnesium oxide with individual retorts without depending on variations in the sunshine hours.

1A and 1B schematically show an example of the structure of a magnesium reduction furnace according to the present invention, in which FIG. 1A is a front view, and FIG. 1B is a cross-sectional view along II in FIG. It is a typical sectional view showing a retort. The relationship between the crucible and the locking part is schematically shown, (A) is a perspective view of the crucible, (B) is a cross-sectional view along II-II when the crucible is inserted, and (C) is the locking part of the crucible. FIG. 2 is a cross-sectional view taken along line II-II when the device is mounted on the device. (A)-(C) is a typical sectional view showing an example of manufacture of a retort. It is a figure which shows the modification 1 of the magnesium reduction furnace by this invention. FIG. 6 is an enlarged cross-sectional view of an upper side of a first retort unit in FIG. 5. FIG. 2 schematically shows Modification 2 of the magnesium reduction furnace according to the present invention, in which (A) is a front view, and (B) is a cross-sectional view along II-II of (A). 3A and 3B schematically show Modification Example 3 of the magnesium reduction furnace according to the present invention, wherein FIG. 3A is a front view, and FIG. 3B is a cross-sectional view taken along line III-III of FIG.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.
FIG. 1 schematically shows an example of the structure of a magnesium reduction furnace 1 according to the present invention, in which (A) is a front view, (B) is a cross-sectional view along II of (A), and FIG. FIG.
As shown in FIG. 1, a magnesium reduction furnace 1 includes a storage unit 3 that stores a briquette 2 containing a magnesium oxide and a reducing agent, and recovers magnesium deposited by depositing magnesium evaporated from the briquette 2 when cooled. , A plurality of retorts 5 in this example, a light collecting unit 6 that collects sunlight on the briquette 2 in one of the plurality of retorts 5, and a plurality of collecting units 4. A stage 7 driven so that the sunlight collected by the light collecting unit 6 is irradiated on one of the plurality of retorts 5 with the retort 5 placed thereon. The stage 7 is driven by a driving unit 8 and a control unit 9 that controls the driving unit 8.

  FIG. 1 shows a case where a plurality of retorts 5 are circumferentially arranged on a stage 7. The plurality of retorts 5 are sequentially irradiated with sunlight collected by the light collection unit 6 by driving the stage 7. The magnesium reduction furnace 1 only needs to be capable of sequentially irradiating sunlight to an amount of briquettes 2 that can be reduced in a short time of about one hour. In this embodiment, the irradiation time of sunlight is estimated to be 8 hours a day, and eight retorts 5 are arranged. However, the number of retorts is appropriately determined according to the size of the light collecting unit 6, the volume of the briquette 2, and the like. Just set it. When the number of retorts 5 is increased, a plurality of light collecting units 6 may be provided, and a plurality of retorts 5 may be provided below each light collecting unit 6. In this case, the plurality of light collecting units 6 and the plurality of retorts 5 may be arranged two-dimensionally.

  As described later, when the retorts 5a to 5h rotate (FIG. 1B), the magnesium reduction furnace 1 of the present invention is a rotary (revolver type) magnesium reduction furnace.

  The light collecting unit 6 is provided above the retort 5 for collecting sunlight, and a lens or a concave mirror such as a parabolic mirror, an elliptical mirror, or a multi-plane mirror can be used. As the lens, a Fresnel lens can be suitably used. The Fresnel lens can be manufactured in a mold, is smaller and lighter than a convex lens, and has an advantage of low cost because it can be manufactured in a mold. The light collecting unit 6 is fixed by a support (not shown), and is arranged so as to be able to track according to the rotation angle of sunlight.

  As shown in FIG. 2, the retort 5 a includes a first retort portion 11 serving as the storage portion 3, a second retort portion 12 serving as the collection portion 4, a first retort portion 11 and a second retort portion 12. And a connection unit 13 for connecting the two.

  The first retort portion 11 includes an inner tube portion 16 in which the crucible 15 is housed, a locking portion 17 for holding the crucible 15 on the inner tube portion 16, an outer tube portion 18, an inner tube portion 16, and an outer tube portion. 18, and a vacuum holding unit 21 formed of a space surrounded by the inner tube 16, the outer tube 18, and the joint 19. The first retort portion 11 is made of heat-resistant glass, and for example, quartz glass can be used.

  The first retort portion 11 has a double tube structure, a structure similar to a so-called thermos structure. That is, the space 21 between the inner tube 16, the outer tube 18 and the joint 19 is kept in a vacuum.

  The crucible 15 can be formed of heat-resistant glass such as quartz glass, like the first retort portion 11. The crucible 15 is fixed by a locking portion 17 formed on the first retort portion 11. The locking portion 17 is made of heat-resistant glass such as quartz glass, and a round bar made of quartz glass is fixed to the first retort portion 11.

An example of the crucible 15 will be described.
3A and 3B schematically show the relationship between the crucible 15 and the locking portion 17, wherein FIG. 3A is a perspective view of the crucible 15, FIG. 3B is a cross-sectional view along II-II when the crucible 15 is inserted, (C) is a sectional view along II-II when the crucible 15 is placed on the locking portion 17.
As shown in FIG. 3 (A), the crucible 15 is formed of a substantially U-shaped quartz tube having a flange 15a provided on the locking portion 17 side. A notch 15b larger than 17 is formed. The crucible 15 is fixed by rotating the crucible 15 after the notch 15b of the crucible 15 has passed through the locking portion 17 when the crucible 15 is inserted into the first retort portion 11 (see FIG. 3B). Then, it can be performed such that the portion other than the cutout portion 15b of the flange portion 15a is supported by the locking portion 17 (see FIG. 3C).

The briquette 2 housed in the crucible 15 is a mixture of magnesium oxide (MgO) and ferrosilicon (FeSi). Magnesium oxide can be recovered from used magnesium fuel cells. Further, as the magnesium oxide, a raw material derived from a mineral such as dolomite ore (CaMg (CO ₃ ) ₂ ) may be used. When dolomite ore is used, flame-retardant magnesium obtained by adding calcium to magnesium can be obtained.

  The cooling section 22 is a place where the evaporated magnesium vapor 27 from the crucible 15 of the first retort section 11 is cooled, and is cooled by air, water, oil or the like.

  The second retort portion 12 is formed of a substantially U-shaped stainless steel metal tube whose one end 13a on the connection portion 13 side is opened and the collection portion 4 side is closed. In the collecting section 4 of the second retort section 12, a cooling section 22 for cooling the collecting section 4 is provided.

  An unillustrated evacuation pipe for evacuating the insides of the first retort unit 11 and the second retort unit 12 may be connected to the collection unit 4 side of the second retort unit 12. A vacuum exhaust device including an on-off valve for opening and closing (not shown), a vacuum pump, and the like may be connected to the evacuation pipe.

  The connection part 13 is composed of a first connection metal fitting 24 and a second connection metal fitting 25. The first connection fitting 24 includes a female screw portion 24b serving as a ring-shaped nut on the outer periphery of a ring-shaped tube 24a. The second connection metal fitting 25 includes a male screw portion 25b that becomes a ring-shaped bolt on the outer periphery of a ring-shaped tube 25a. The end portion 11a of the first retort portion 11 is inserted into the ring-shaped tube 24a, and the outermost peripheral surface of the end portion 11a contacts the inner peripheral surface of the female screw portion 24b. The convex portion 12a of the second retort portion 12 is inserted into the ring-shaped tube 25a, and the outermost peripheral surface of the convex portion 12a contacts the inner peripheral surface of the male screw portion 25b.

  The connecting portion 13 has a heat insulating function so that radiant heat from the crucible 15 does not reach the cooling portion 22 side of the retort 5a.

The first retort unit 11 and the second retort unit 12 are connected as follows.
The first retort portion 11 is inserted into the first connection fitting 24.
Next, the second retort portion 12 is inserted into the second connection fitting 25.
Next, a metal packing 26 is inserted between the left end of the first retort portion 11 and the right end of the second retort portion 12, and a bolt and a nut are screwed together, so that the first retort portion 11 and the The two retort portions 12 are connected by metal packing 26 so as to maintain airtightness.

  The right end of the second retort portion 12 may have a groove (not shown) into which the metal packing 26 is inserted. As the metal packing 26, a packing formed of copper (Cu) or the like for a vacuum flange can be used.

FIGS. 4A to 4C are schematic cross-sectional views illustrating an example of manufacturing the first retort portion 11.
As shown in FIG. 4A, a second quartz tube serving as an outer tube 18 is provided at the left end of a first quartz tube 31 serving as an inner tube 16 provided with a quartz member serving as a locking portion 17 in advance. 32 is welded with an oxyhydrogen burner. By this welding, a joint portion 19 is formed, and a double tube portion of the first retort portion 11 including the inner tube portion 16 and the outer tube portion 18 is formed. The second quartz tube 32 is connected to an evacuation pipe 33 for evacuation. In this state, the double tube section is not yet maintained in a vacuum.
Next, as shown in FIG. 4B, a vacuum evacuation device (not shown) is connected to the end of the evacuation pipe 33, and a predetermined portion of the evacuation pipe 33 is evacuated while evacuating the double pipe section. A sealing portion 34 is formed in the evacuation pipe 33 by sealing with an oxyhydrogen burner, the space between the inner pipe section 16 and the outer pipe section 18 is evacuated, and the vacuum holding section 21 (see FIG. 2) is opened. Can be formed.
Next, as shown in FIG. 4C, an end 19a is formed on the left end of the first quartz tube 31 so as to be in contact with the first connection fitting 24. Thereby, the first retort portion 11 can be manufactured.

  As shown in FIG. 2, the briquette 2 housed in the crucible 15 of the first retort unit 11 of the magnesium reduction furnace 1 of the present invention is heated to 1200 ° C. to 1400 ° C. By being heated, magnesium oxide is reduced from the briquette 2 by ferrosilicon, and magnesium vapor 27 is generated. This magnesium vapor 27 is solidified in the recovery unit 4 of the second retort unit 12 and reduced to magnesium 28. You.

  The dimensions of the briquette 2 are set so that the magnesium 28 evaporates in about one hour. When the reduction of the briquettes 2 of the retort 5a is completed, the briquettes 2 of the retort 5b are then reduced. Similarly, the briquettes 2 of the retorts 5c to 5h are reduced in this order, that is, sequentially.

The reduction reaction between magnesium oxide and ferrosilicon is shown in the following equation (1).
2MgO + Si → 2Mg + SiO ₂ (1)

  The above-mentioned retorts 5a to 5h are moved to the focal point of the light collecting unit 6 approximately every hour by the driving unit 8. The driving unit 8 moves to the focal point of the light collecting unit 6 approximately every hour and drives the stage 7 so as to track the sunlight. The irradiation time of sunlight to each of the retorts 5a to 2h can be performed at predetermined time intervals when the weather is fine. Furthermore, the irradiation time of the sunlight to each of the retorts 5a to 5h may be adjusted for each of the retorts 5a to 5h in accordance with the intensity fluctuation of the sunlight due to the weather.

  When the magnesium reduction furnace 1 of the present invention is operated at the equator, sunlight enters from almost 90 degrees, so that the magnesium reduction furnace 1 may track the sun in the east-west direction.

  The control unit 9 that controls the driving unit 8 includes a computer, software that controls the driving unit 8, software that tracks the sun, and the like. If the longitude and latitude are set by software for tracking the sun, the sunlight can be collected by the light collecting unit 6 for each of the retorts 5a to 5h.

  According to the magnesium reduction furnace 1 of the present invention, the sunlight that is incident on a sunny day for about 8 to 10 hours is sequentially irradiated to the retorts 5a to 5h approximately every hour, and the briquettes in the retorts 5a to 5h are irradiated. 2 can be efficiently reduced to magnesium 28.

  Thus, in a solar furnace having an approximate diameter of about 10 m, which is reasonably dimensional, a retort 5 a to 5 h having an inner diameter of about 30 cm, which is optimal for thermal reduction, is reduced almost every hour, and magnesium oxide can be efficiently removed. Can be reduced to magnesium 28. The reduction time of one retort 5a is approximately one hour, the reduction of magnesium is not zero even when it is cloudy, the reduction of several retorts is sufficiently possible, and the reduction reaction of magnesium oxide can be efficiently promoted. .

  Specifically, when the size of the retort 5a increases, temperature unevenness occurs in the retort 5a, and the magnesium vapor 27 solidifies at the outlet of the crucible 15 and clogs the flow path of the magnesium vapor 27. By providing and subdividing it, it can be prevented and the reduction reaction of magnesium oxide can be efficiently promoted.

(Modification 1 of magnesium reduction furnace)
FIG. 5 is a diagram showing a first modification of the magnesium reduction furnace 1 according to the present invention, and FIG. 6 is an enlarged cross-sectional view of an upper side of the first retort portion 51 of FIG.
The first retort section 51 of the magnesium reduction furnace 40 shown in FIG. 5 is different from the first retort section 11 of FIG. 2 in that the first retort section 51 has a reflecting mirror 46. The other configuration is the same as that of the retort 5a shown in FIG.

  The first retort unit 51 shown in FIG. 6 includes an entrance window 47 into which sunlight enters, and a reflecting mirror 46. The reflecting mirror 46 is provided in a region other than the entrance window 47 of the outer tube 18. That is, the reflecting mirror 46 is made of a metal film formed on the surface of the outer tube portion 18 facing the crucible 15 of the first retort portion 51. The metal film of the reflecting mirror 46 can be formed by plating or vapor deposition.

  As described above, in the magnesium reduction furnace 40 using the first retort unit 51, by providing the first retort unit 51 with the reflecting mirror 46, heat radiated from the crucible 15 is reflected by the reflecting mirror 46. Then, the heat can be returned to the crucible 15, so that the heat loss can be reduced. In addition, since the incident window portion 47 into which the sunlight enters is always irradiated with the sunlight, the entrance window portion 47 has a structure that is not clouded by the magnesium vapor 27 or the like.

  The efficiency of converting sunlight energy into heat by the light-collecting unit 6 is high, and when the sunlight is directly condensed on the crucible 15 for reduction, the conventional pigeon method, that is, when the crucible is heated by external heating and heat transfer Energy efficiency is significantly improved. In particular, when considering sunlight as primary energy, light is condensed by a lens or a reflector, and the light is condensed from 5000 to 10,000 times, so that the efficiency is easily increased from 1300 ° C to 2000 ° C by more than 90%. Can be converted to heat energy with a high efficiency.

  Furthermore, it is essential that the Pigeon method be reduced in a vacuum state, and this condition is that the thermal energy is lost, that is, two of the losses, convection, heat transfer, and radiation, are almost completely eliminated. Can be prevented. According to the present invention, the provision of the above-mentioned reflecting mirror 46 can further eliminate radiation loss. Thereby, according to the present invention, the efficiency of the pigeon method can be greatly improved.

  According to the present invention, the briquettes 2 are dispersed, that is, stored in small portions in each of the storage portions 3 of the plurality of retorts 5, and the briquettes 2 in one retort are irradiated with sunlight collected by the light collection unit 6. Then, by cooling the recovery unit 4, the magnesium oxide can be efficiently reduced by the individual retorts 5a to 5h without depending on the variation of the sunshine time.

(Modification 2 of magnesium reduction furnace)
7A and 7B schematically show Modification 2 of the magnesium reduction furnace 1 according to the present invention, wherein FIG. 7A is a front view, and FIG. 7B is a cross-sectional view along II-II in FIG.
The magnesium reduction furnace 50 shown in FIG. 7 is different from the magnesium reduction furnace 1 shown in FIG. 1 in that a stage 7 in which two light collecting units 6a and 6b are provided and 16 retorts 5a to 5p can be arranged. It is. The two light collecting units 6a and 6b are disposed above the retorts 5a and 5i. Other configurations are the same as those of the magnesium reduction furnace 1 shown in FIG.

In the magnesium reduction furnace 50 shown in FIG. 7, eight retorts 5a to 5h are sequentially heated by the right focusing unit 6a to reduce magnesium oxide. At the same time, eight retorts 5i to 5p are sequentially heated by the left condenser unit 6b to reduce magnesium oxide.
Thus, assuming that the reduction time of each retort is one hour as in the case of the magnesium reduction furnace 1 of FIG. 1, in the magnesium reduction furnace 50 shown in FIG. 7, the magnesium oxide in the sixteen retorts 5a to 5p in eight hours is reduced. Reduction can be performed.

(Modification 3 of magnesium reduction furnace)
FIGS. 8A and 8B schematically show Modification 3 of the magnesium reduction furnace 1 according to the present invention, wherein FIG. 8A is a front view, and FIG. 8B is a sectional view taken along line III-III of FIG.
The magnesium reduction furnace 60 shown in FIG. 8 is different from the magnesium reduction furnace 1 shown in FIG. 1 in that a stage 7 in which four condensing units 6a to 6d are provided and 16 retorts 5 can be disposed, and This is the point that the transport unit 65 is provided. The four light-collecting units 6a to 6d are arranged at approximately 90 degrees above the retorts 5a, 5i, 5e, and 5m. Other configurations are the same as those of the magnesium reduction furnace 1 shown in FIG.

  In the magnesium reduction furnace 60 shown in FIG. 8, the retort 5 is heated by the four light collecting units 6a to 6d. By the right light collecting unit 6a, the four retorts 5a to 5d are sequentially heated to reduce magnesium oxide. At the same time, four retorts 5i to 5l are sequentially heated by the left light collecting unit 6b to reduce magnesium oxide.

Further, the four retorts 5e to 5h are sequentially heated by the light collecting unit 6c on the near side, and magnesium oxide is reduced. By the light collecting unit 6d on the far side, the four retorts 5m to 5p are sequentially heated to reduce magnesium oxide.
Accordingly, assuming that the reduction time of each retort is one hour as in the case of the magnesium reduction furnace 1 shown in FIG. 1, in the magnesium reduction furnace 60 shown in FIG. 8, the magnesium oxide in the sixteen retorts 5a to 5p is removed in four hours. Can be reduced.

  Next, the 16 retorts 5a to 5p for which the reduction has been completed are transported outside the stage 7 by the retort transport unit 65. Then, the retort 5 containing briquettes for performing the next reduction is disposed on the stage 7 by the retort transport unit 65. By repeating the heating for 4 hours in the same manner as the above, the magnesium oxide in the 16 retorts 5 is reduced in the next 4 hours. Here, a plurality of retort transfer units 65 may be provided to shorten the transfer time.

  Therefore, assuming that the reduction time of each retort 5 is one hour as in the case of the magnesium reduction furnace 1 in FIG. 1, the magnesium reduction furnace 60 shown in FIG. 8 reduces magnesium oxide in 32 retorts 5 in eight hours. Can be.

The magnesium reduction furnace 1 shown in FIG. 1 has one condensing unit and reduces magnesium oxide in the eight retorts 5a to 5h in 8 hours, whereas the magnesium reduction furnace 50 shown in FIG. Since the number of the light collecting units 6 is two, the magnesium oxide in the sixteen retorts 5 can be reduced.
Further, in the magnesium reduction furnace 60 shown in FIG. 8, the number of the light collecting units 6 is four, and the magnesium oxide in the 32 retorts 5 can be reduced. That is, the retort 5 that can be subjected to the reduction process can be increased in proportion to the light collection unit 6.

  As a rough guide, if the number of the retorts 5 is n (here, n is 2 or more), the number of the light collecting units 6 may be m (1 ≦ m <n).

  According to the magnesium reduction furnaces 1 and 40 of the present invention, the briquettes 2 are dispersed, that is, stored in small portions in each of the storage portions 3 of the plurality of retorts 5, and the briquettes 2 in one retort 5 are condensed by the condensing unit 6. By irradiating the condensed sunlight and cooling the recovery unit 4, the magnesium oxide can be efficiently reduced by the individual retorts 5a to 5h without depending on the variation of the sunshine time.

  According to the magnesium reduction furnaces 50 and 60 of the present invention, the number of retorts 5 to be reduced can be increased by providing a plurality of light-collecting units 6 to reduce magnesium oxide efficiently.

  The present invention is not limited to the above embodiment, and various modifications are possible within the scope of the invention described in the claims, and it goes without saying that they are also included in the scope of the present invention. Nor.

1, 40, 50, 60: Magnesium reduction furnace 2: Briquette 3: Storage unit 4: Recovery unit 5, 45a: Retort 6: Condensing unit 7: Stage 8: Drive unit 9: Control unit 11, 51: First Retort portion 12: second retort portion 12a: end portion 13: connection portion 15: crucible 15a: flange portion 15b: notch portion 16: inner tube portion 17: locking portion 18: outer tube portion 19: joining portion 19a: end Part 21: Vacuum holding part 22: Cooling part 24: First connection fitting 24a: Ring-shaped tube 24b: Female screw part 25: Second connection fitting 25a: Ring-shaped pipe 25b: Male screw part 26: Metal packing 27: Magnesium vapor 28: Magnesium 31: First quartz tube 32: Second quartz tube 33: Vacuum piping 34: Sealing section 46: Reflecting mirror 47: Incident window section 65: Retort transport section

Claims (8)

A plurality of retorts each including a storage unit that stores a briquette containing a magnesium oxide and a reducing agent, and magnesium that is evaporated from the briquette by cooling, and a recovery unit that recovers the deposited magnesium.
A light collecting unit that collects sunlight on the briquette in one of the plurality of retorts,
In a state where the plurality of retorts are mounted, a stage driven so that sunlight collected by the light collection unit is irradiated to one of the plurality of retorts,
A magnesium reduction furnace.   2. The magnesium reduction furnace according to claim 1, wherein the plurality of retorts are circumferentially arranged on the stage, and the sunlight collected by the light collection unit is sequentially irradiated by driving the stage. 3. .   3. The magnesium reduction furnace according to claim 1, further comprising: a driving unit that drives the stage; and a control unit that controls the driving unit. 4.   3. The magnesium reduction furnace according to claim 1, wherein the retort includes a first retort part including a double tube serving as a storage part, and a second retort part including a recovery part. 4.   The magnesium reduction furnace according to claim 4, wherein the first retort portion has an inner tube portion and an outer tube portion, and the space between the inner tube portion and the outer tube portion is evacuated.   The magnesium reduction furnace according to claim 5, wherein a crucible is housed inside the inner tube portion, and the briquette is housed in the crucible.   7. The magnesium reduction furnace according to claim 5, wherein the outer tube includes an incident window through which the sunlight enters and a reflecting mirror. 8.   The magnesium reduction furnace according to claim 7, wherein the reflecting mirror is formed on a surface of the outer tube.

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