Method and apparatus for producing Ca and / or Mg oxides

Abstract

To continuously and efficiently obtain Ca and / or Mg oxides free of fuel-derived impurities from raw materials such as limestone and dolomite. [Solution] A raw material containing Ca and / or Mg carbonate or Ca and / or Mg hydroxide is irradiated with laser light to calcine it, causing it to emit light, and then further calcined by thermal radiation from the emitting state to produce a product containing Ca and / or Mg oxide.

Description

Technical Field

[0001] The present invention relates to a method for producing an oxide of Ca and / or Mg, including a step of obtaining a product containing the corresponding oxide of Ca and / or Mg by irradiating a raw material containing a carbonate of Ca and / or Mg or a hydroxide of Ca and / or Mg with laser light, and an apparatus used in the production method.

Background Art

[0002] Oxides of calcium and magnesium (CaO / MgO) are widely used in ironmaking, cement raw materials, paper making, building materials raw materials, desiccants, fertilizers, food additives, etc. CaO and MgO have conventionally been produced by firing minerals such as limestone mainly containing calcium carbonate (CaCO3), magnesite mainly containing magnesium carbonate (MgCO3), and dolomite containing CaCO3 and MgCO3 in a combustion furnace using a fuel such as heavy oil in a melting furnace or the like. However, CaO and MgO produced in such a furnace are likely to contain impurities derived from the fuel.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Therefore, an object of the present invention is to obtain a method for producing CaO and MgO without impurities derived from fuel, continuously and efficiently, and an apparatus used in the method.

Means for Solving the Problems

[0005] The present invention includes the following aspects 1 to 4: [Aspect 1] A method for obtaining a product containing the corresponding Ca and / or Mg oxide from a starting material containing a Ca and / or Mg carbonate or Ca and / or Mg hydroxide, (Step 1) A step of irradiating the raw material with laser light to form a hole in the area irradiated with laser light; (Step 2) A step in which the raw material on the inner circumference of the hole is fired by irradiation with laser light; (Step 3) A step of increasing the temperature of the inner circumference by further irradiation with laser light, causing the inner circumference to emit light; and (Step 4) A step in which the raw material at the periphery of the inner circumference is fired by thermal radiation from the inner circumference in the aforementioned luminescent state. A method for producing oxides of Ca and / or Mg, including the aforementioned method. [Aspect 2] A method for producing Ca and / or Mg oxides according to Embodiment 1, comprising step 5 of discharging the product containing Ca and / or Mg oxides generated by the calcination in steps 2 and 4, and adding new raw materials. [Aspect 3] A cylindrical container having a peripheral wall and upper and lower ends, for holding raw materials containing Ca and / or Mg carbonate or Ca and / or Mg hydroxide, A raw material supply unit for supplying raw materials from the top of the cylindrical container, A discharge section is installed on the lower side of the lower end of the cylindrical container, An apparatus for obtaining a product containing corresponding Ca and / or Mg oxides from the raw materials, including the above, A laser beam irradiation unit is installed on the upper side of the upper end of the cylindrical container, The upper end of the cylindrical container is provided with a light-transmitting section that allows the laser light emitted from the laser light irradiation section to pass through to the inside of the cylindrical container, The inside of the cylindrical container constitutes a reaction space that generates the product formed by firing the raw material filled inside the container upon irradiation with the laser light. The discharge unit includes a mechanism capable of controlling the stopping and starting of the discharge of the product from the lower end of the cylindrical container. An apparatus for producing Ca and / or Mg oxides, characterized by the features described above. [Aspect 4] The manufacturing apparatus according to embodiment 3, characterized in that a concave hole is formed on the surface of the raw material filled inside the cylindrical container. [Aspect 5] The manufacturing apparatus according to embodiment 3 or embodiment 4, characterized in that the cylindrical container is covered with a heat-shielding material and / or an insulating material. [Aspect 6] The manufacturing apparatus according to embodiment 3 or embodiment 4, wherein a focusing lens is installed between the cylindrical container and the laser light irradiation unit.

[0006] In this specification, "carbonate of Ca and / or Mg or hydroxide of Ca and / or Mg" means one selected from calcium carbonate (CaCO3), magnesium carbonate (MgCO3), calcium magnesium carbonate (CaMg(CO3)2), calcium hydroxide (Ca(OH)2), and magnesium hydroxide (Mg(OH)2), or a mixture of two or more selected from these. Furthermore, "oxide of Ca and / or Mg" means calcium oxide (CaO) or magnesium oxide (MgO) or a mixture of these two.

[0007] In the present invention, a raw material containing a carbonate of Ca and / or Mg or a hydroxide of Ca and / or Mg is fired by thermal radiation from the oxide corresponding to the raw material, which has become luminescent due to laser irradiation, thereby producing a product containing the corresponding oxide of Ca and / or Mg.

[0008] In the present invention, the raw materials containing Ca and / or Mg carbonates are, for example, limestone mainly containing CaCO3, magnesite mainly containing MgCO3, dolomite containing CaCO3 and MgCO3, or mixtures thereof. The raw materials containing Ca and / or Mg hydroxides are, for example, slaked lime which is Ca(OH)2, talc (brucite) which contains Mg(OH)2, portlandite which contains Ca(OH)2 and Mg(OH)2, or mixtures thereof. In the present invention, the raw material may be a mineral or rock containing a carbonate of Ca and / or Mg or a hydroxide of Ca and / or Mg.

[0009] In the present invention, the raw material may be in bulk form, but small pieces, granules, or powder are preferred in order to efficiently discharge the product after calcination. In the present invention, the raw material is, for example, granules with a particle size of 2.0 mm or less, preferably 0.1 mm to 1.0 mm, and more preferably 0.3 mm to 0.8 mm.

[0010] In the present invention, the laser light is, for example, laser light in the mid-infrared region, the near-infrared region, or the visible light region, preferably laser light in the near-infrared region, and more preferably laser light with a wavelength of 1090 nm. A semiconductor laser can also be used as the laser light generator. In this invention, the laser light may be irradiated directly onto the raw material, or it may be focused using a focusing lens before irradiation.

[0011] In this invention, the raw material is first subjected to laser irradiation to form a hole, then the raw material on the inner circumference of the hole is fired by the laser light diffusely reflected from the inner surface of the hole, and when the laser light is irradiated again, the temperature of the inner circumference of the hole rises due to the absorption of the laser light. The temperature rise temporarily stagnates at around 1000°C for limestone and at 700°C to 900°C for dolomite and magnesite, but when the laser light is irradiated again, the inner circumference reaches a high temperature of approximately 1900°C and becomes luminous. The luminous inner circumference emits thermal radiation, and the raw material outside the inner circumference is fired and its temperature rises due to the thermal radiation from the luminous inner circumference. In addition, the raw material outside the inner circumference may also be fired by irradiation with laser light diffusely reflected within the hole. Furthermore, the raw material outside the inner circumference may also be fired by heat conduction from adjacent raw materials. Due to these factors, the raw materials on the outer side of the inner circumference, which are not directly irradiated by the laser light, can be calcined to form a product containing Ca and / or Mg oxides.

[0012] In the manufacturing method of the present invention, all of the following steps occur by irradiating the raw material with laser light: step 1, forming a hole in the raw material; step 2, firing the raw material on the inner circumference of the hole; step 3, raising the temperature of the raw material on the inner circumference of the hole to bring it into a luminescent state; and step 4, firing the raw material on the periphery of the inner circumference by thermal radiation from the luminescent raw material. The laser light irradiation time required to perform all four steps of the manufacturing method of the present invention varies depending on, for example, the distance from the focal point of the laser light to the top of the raw material in the cylindrical container, the amount of raw material, the cross-sectional area of ​​the cylindrical container, and the length of the cylinder.

[0013] The aforementioned holes are formed with a bottom, and may be formed by inserting a rod-shaped jig or drill or other drilling equipment into the surface of the raw material beforehand. Alternatively, a recessed hole formed in the surface of the raw material by irradiating the surface of the raw material with laser light is also preferable. It is presumed that the recessed hole is formed by the removal process or shrinkage due to melting of the raw material irradiated with laser light. The hole is preferably elongated in shape, with a depth greater than the opening diameter at the top. This is because an elongated shape allows for efficient firing of the raw material by scattering the laser light incident inside the hole, preventing it from escaping to the outside. Furthermore, a wedge-shaped hole with a depth greater than the opening diameter is also preferable. Furthermore, the aforementioned holes do not refer to gaps that naturally form between small pieces, granules, or powders when the raw material is in the form of small pieces, granules, or powders and is filled into a cylindrical container.

[0014] The manufacturing apparatus of the present invention includes a cylindrical container, a raw material supply section, and a discharge section, and this apparatus can be used to obtain a product containing the corresponding Ca and / or Mg oxide from a raw material containing Ca and / or Mg carbonate or Ca and / or Mg hydroxide.

[0015] The cylindrical container according to the manufacturing apparatus of the present invention has a peripheral wall and upper and lower ends, and its interior constitutes a reaction space in which raw materials are calcined by laser irradiation to produce products. Furthermore, the cylindrical container of the manufacturing apparatus according to the present invention has a light-transmitting section at the upper end that allows laser light to pass through to the interior. The cylindrical container of the manufacturing apparatus of the present invention is made of a heat-resistant material, for example, quartz glass, because the raw material filled therein becomes high in temperature by irradiation with laser light. Further, in order to suppress the heat of the raw material for firing from escaping to the outside of the container, it is preferable that the outer side and the upper end portion of the cylindrical container are covered with a heat insulating material (for example, aluminum) or a heat insulating material. When the upper end portion of the cylindrical container is covered with a lid portion of a heat insulating material or a heat insulating material, the light transmitting portion may be provided on the lid portion. The light transmitting portion may be an opening or a glass material that transmits laser light, and is preferably an opening.

[0016] In the manufacturing apparatus of the present invention, a raw material supply unit for supplying a raw material is installed above the cylindrical container. The raw material supply unit may have a hopper, a connecting pipe, a raw material discharge port, and the like. Further, the raw material discharge port may be arranged at a position that does not obstruct the irradiation path of the laser light irradiated from the laser light irradiation unit. Further, the manufacturing apparatus of the present invention may supply the raw material from the raw material supply unit simultaneously with or after discharging the product from the discharge unit installed below the lower end of the cylindrical container.

[0017] In the manufacturing apparatus of the present invention, a discharge unit is installed below the lower end of the cylindrical container. The discharge unit includes a mechanism capable of controlling the stop and start of the discharge of the product. For example, it is a shutter, a rotary valve, a screw feeder, a table feeder, or a slide gate damper, and is preferably a shutter. When the discharge unit is a shutter, the discharge unit has an opening / closing mechanism and a shutter holding unit that holds the opening / closing mechanism, and the opening / closing mechanism can control the stop and start of the discharge of the product from the lower end of the cylindrical container. When the discharge unit is a shutter, the opening / closing mechanism of the discharge unit may be, for example, in a form in which the center opens when two slide plates move apart to the left and right, or in a form in which the discharge hole opens when a slide plate at the lower part of the plate with the discharge hole moves to the left or right. Furthermore, the control of stopping and starting the discharge of the product may be manual or electric. The timing of stopping and starting the discharge of the product may be determined by the operator of the device, or it may be done at regular intervals, or it may be determined according to settings such as temperature conditions.

[0018] In the manufacturing apparatus of the present invention, it is preferable to stop the discharge of the product from the discharge section while the raw material is being calcined, and to start the discharge of the product from the discharge section once the product has been produced. The discharge section may be equipped with a clogging prevention member to prevent clogging of the product from hindering the control of stopping and starting discharge from the discharge section. The manufacturing apparatus of the present invention can continuously produce products by repeatedly stopping the discharge of products from the discharge section, supplying raw materials, irradiating with laser light, and discharging the products from the discharge section.

[0019] Furthermore, the manufacturing apparatus of the present invention may be provided with a cooling section between the lower end of the cylindrical container and the discharge section. By installing a cooling section, it is possible to suppress the deterioration of the mechanism for discharging the product due to heat, as the raw material in the luminescent state is at a high temperature.

[0020] The manufacturing apparatus of the present invention has a laser beam irradiation unit installed on the upper side of the upper end of a cylindrical container. The laser light emitted from the laser light irradiation unit is, for example, laser light in the mid-infrared region, near-infrared region, or visible light region, preferably laser light in the near-infrared region, and more preferably laser light with a wavelength of 1090 nm. The laser light emitted from the laser light irradiation unit may be emitted directly from the laser light generator, or it may be laser light transmitted via an optical fiber or mirror installed to guide the laser light from the laser light generator. A semiconductor laser may also be used as the laser light generator. The laser light emitted from the laser light irradiation unit passes through a light-transmitting section provided at the top of the cylindrical container of the manufacturing apparatus of the present invention and irradiates the raw material filled inside the cylindrical container. Furthermore, in the manufacturing apparatus of the present invention, a focusing lens may be installed between the light-transmitting section at the top of the cylindrical container and the laser light irradiation section to irradiate a certain area of ​​the raw material surface with laser light and adjust the firing range. [Effects of the Invention]

[0021] The present invention makes it possible to provide a product containing high-purity Ca and / or Mg oxides that are free from impurities derived from the fuel. Furthermore, the present invention makes it possible to continuously produce a product containing the corresponding Ca and / or Mg oxide from a raw material containing Ca and / or Mg carbonate or Ca and / or Mg hydroxide. [Brief explanation of the drawing]

[0022] [Figure 1] This is a schematic diagram showing the entire manufacturing apparatus 1 from an end view. [Figure 2] (a) shows an example of the manufacturing apparatus 1 with the lid heat shield material 25 placed over the cylindrical container 2 of the present invention. It is a photograph taken from diagonally above showing the side heat shield material 26 (not shown) and the side heat insulation material 27 wrapped around the outer surface of the side heat shield material 26. (b) is a photograph of the cylindrical container 2 taken from directly above. The black dot inside the circle in the center of (b) is the laser beam incident point and indicates hole H. [Figure 3] The graphs show the amount of firing per unit irradiation time when the surface of the raw material is fired and when the inside of the raw material is fired in Example 1. [Figure 4] (a) is a photograph showing the process of irradiating a cylindrical limestone raw material 6 with laser light from above, creating a hole in the upper surface of the raw material while causing it to emit light. (b) is a schematic diagram showing the shape of the surface of the cylindrical limestone in (a) that has been provisionally cut in the vertical direction, and the position of the laser light. [Figure 5]These are photographs of cross-sections of cylindrical limestone after irradiation with laser light in Example 2. Figure 5(a) shows the results after irradiation for 10 seconds, Figure 5(b) for 20 seconds, Figure 5(c) for 150 seconds, and Figure 5(d) for 600 seconds. The white areas in the drawings represent the fired areas, while the dark gray areas represent the unfired areas. [Figure 6] The images in Example 4 show cross-sections of granular limestone after irradiation with laser light. (a) shows the case with a focal length of 60 mm and irradiation time of 150 seconds, (b) shows the case with a focal length of 60 mm and irradiation time of 300 seconds, (c) shows the case with a focal length of 60 mm and irradiation time of 600 seconds, (d) shows the case with a focal length of 150 mm and irradiation time of 150 seconds, (e) shows the case with a focal length of 150 mm and irradiation time of 300 seconds, (f) shows the case with a focal length of 150 mm and irradiation time of 600 seconds, (g) shows the case with a focal length of 300 mm and irradiation time of 150 seconds, (h) shows the case with a focal length of 300 mm and irradiation time of 300 seconds, and (i) shows the case with a focal length of 300 mm and irradiation time of 600 seconds. The white areas in the drawings represent the fired areas, and the dark gray areas represent the unfired areas. [Figure 7] In Example 4, the change in depth of the firing range in Figures 6(a) to (i) is shown in the graph. Note that f represents the focal length symbol. [Figure 8] The graph shows the change in the width of the firing range (a) to (i) in the embodiment shown in Figure 6. Note that f represents the focal length symbol. [Figure 9] The example graph shows the temperature change at the laser-irradiated area when limestone is continuously irradiated with laser light for 24 seconds. [Figure 10] The example shows a photograph illustrating the luminescence that occurs when limestone is continuously irradiated with laser light. [Figure 11] The reference example shows the temperature distribution of the limestone surface observed with an infrared camera when the limestone is continuously irradiated with laser light and emits light (approximately 1900°C, left side of the photo), and when it is fired by laser light irradiation but does not emit light (around 1000°C, right side of the photo). [Figure 12] This is an end view showing an example of another discharge structure in manufacturing apparatus 1. [Modes for carrying out the invention]

[0023] Embodiments of the present invention will be described in detail below with reference to the drawings. In this specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant explanations will be omitted.

[0024] Figure 1 shows an end view of the entire manufacturing apparatus 1 of the present invention. The manufacturing apparatus 1 of the present invention includes a cylindrical container 2, a raw material supply unit 3, and a discharge unit 4. A laser beam irradiation unit 5 is installed on the upper side of the cylindrical container 2 of the manufacturing apparatus 1 of the present invention. Holes (indented holes) H are formed in the raw material 6 filled in the cylindrical container 2 by the laser beam 51.

[0025] Figure 2(a) is a photograph taken from an oblique angle above showing a cylindrical container 2, which has heat shielding material and heat insulation material installed, being irradiated with laser light. Figure 2(b) is a photograph taken from directly above the cylindrical container 2 after the lid heat shielding material 25 has been removed following laser light irradiation. In Figure 2(b), the outer periphery, side heat shielding material 26, and cylindrical container 2 are arranged concentrically. Granular raw material 6 is filled inside the cylindrical container 2, and a hole H is formed in the center (laser light incidence point).

[0026] The cylindrical container 2 of the manufacturing apparatus 1 of the present invention is provided with a peripheral wall 21, an upper end 22, and a lower end 23. The inside of the cylindrical container 2 is formed as a reaction space 24, which is filled with raw material 6. The top of the cylindrical container 2 is covered with a lid heat shield 25, and the peripheral wall 21 is covered with a side heat shield 26. The side heat shield 26 is further covered on its outside with a side heat insulating material 27. These heat shields and heat insulating materials help to reduce the slowdown or cessation of the calcination of the raw material by preventing heat from being drawn from the reaction space 24 through the portion of the cylindrical container 2 that is in contact with the peripheral wall 21. Furthermore, the cylindrical container 2 is held in place by the lower insulating material 71.

[0027] The lid heat shield 25 is equipped with a light-transmitting section 251 that allows the laser beam 51 emitted from the laser beam irradiation section 5 to pass through to the inside of the cylindrical container 2. In Figure 1, raw materials are supplied to the light-transmitting section 251 that allows the laser beam to pass through from the raw material discharge port 34 of the raw material supply section 3, but the lid heat shield 25 may also be provided with a raw material supply opening (not shown) separate from the light-transmitting section 251. The side heat shield material 26 is held in place by the heat shield material holding part 28 located below it.

[0028] The raw material supply unit 3 of the manufacturing apparatus 1 of the present invention is installed at the top of the cylindrical container 2. The raw material supply unit 3 includes a hopper 31, a funnel 32, a connecting pipe 33, and a raw material discharge port 34. The raw material 6 can be supplied to the reaction space 24 inside the cylindrical container 2 from the raw material discharge port 34 at the end of the connecting pipe 33 through the light-transmitting portion 251 of the heat-shielding material 25 of the lid.

[0029] A laser beam irradiation unit 5 is installed at the top of the cylindrical container 2. The laser beam 51 irradiated from the laser beam irradiation unit 5 is focused by a focusing lens 52, passes through the light-transmitting portion 251 of the heat-shielding material 25 of the lid, punctures the raw material 6 in the reaction space 24, burns it, causes it to emit light, and produces the product 8.

[0030] In the manufacturing apparatus 1 of the present invention shown in Figure 1, a cooling unit 7 is installed between the lower end of the cylindrical container 2 and the discharge section 4. The cooling unit 7 consists of a lower insulating material 71, a heat sink 72, and an outlet 73. The peripheral wall 21 of the cylindrical container 2 is connected to the lower insulating material 71 at its lower end 23, and the lower insulating material 71 is connected to the heat sink 72. The cylindrical container 2 and the heat sink 72 have an outlet 73, which penetrates both the cylindrical container 2 and the heat sink 72. The product 8 can be discharged from the cylindrical container 2 through the outlet 73 of the cooling unit 7.

[0031] In the manufacturing apparatus 1 of the present invention shown in Figure 1, the discharge section 4 is installed below the lower end 23 of the cylindrical container 2. In the manufacturing apparatus 1 of the present invention shown in Figure 1, the discharge section 4 is a shutter and has an opening / closing mechanism 41 and a shutter holding part 42 that holds the opening / closing mechanism 41. The opening / closing mechanism 41 of the discharge section 4 in Figure 1 is a manually operated type that opens in the center. Once the raw materials 6 in the reaction space 24 are calcined by the laser light irradiated from the laser light irradiation unit 5 and a product 8 is obtained, the opening / closing mechanism 41 of the discharge section 4 can be opened to discharge the product 8 containing Ca and / or Mg oxides from the cylindrical container 2. The discharged product 8 is collected by a product recovery container (not shown) installed below the discharge section 4.

[0032] (Example) Luminous state and thermal radiation The temperature change at the irradiated area of ​​a limestone (a rectangular prism measuring 25mm x 25mm x 10mm) was measured when it was continuously irradiated with an 80W laser beam for 24 seconds. Figure 9 shows a graph of the temperature change. From this graph, it was confirmed that when limestone is irradiated with laser light, its temperature rises, the temperature rise stagnates for a certain period of time when it reaches around 1000°C, and if the laser light is continued, it reaches a high temperature of 1900°C, at which point the temperature rise stagnates again. In addition, no luminescence was observed when the limestone temperature was stagnant at around 1000°C, but luminescence and thermal radiation were observed when the limestone temperature reached 1900°C. A photograph of the luminescence is shown in Figure 10.

[0033] Furthermore, Figure 11 shows the results of observing the temperature distribution on the limestone surface using an infrared camera when the limestone was continuously irradiated with laser light and became luminous (approximately 1900°C, left side of the photograph) and when it was fired by laser light irradiation but did not become luminous (around 1000°C, right side of the photograph). From these infrared camera photographs, it can be seen that when the limestone became luminous, the maximum temperature rose to approximately 1800°C (the black area in the center of the left side of the photograph). Compared to the right side of the photograph where the limestone was not luminous, the high-temperature area was wider, suggesting that thermal radiation occurred from the luminous area, resulting in firing over a wider area than the laser-irradiated area.

[0034] (Example) Measurement of laser light irradiation and CO2 residual amount The amount of residual CO2 in quicklime obtained by calcining limestone by irradiating it with laser light until it emitted light was measured using the infrared absorption method specified in JIS R9011. The raw material limestone (CaCO3) had a CO2 content of approximately 44% by mass. When the amount of residual CO2 in quicklime (CaO) obtained by irradiating it with laser light until it emitted light was measured, the residual CO2 content was 2.0% by mass or less. Quicklime with a low residual CO2 content is considered to be of high purity and quality, and JIS R9001 specifies that quicklime with a residual CO2 content of 2.0% by mass or less is of special grade. Therefore, the quicklime obtained by irradiating it with laser light until it emitted light was of high purity and quality, meeting the requirements for special grade. [Examples]

[0035] The following are specific examples of the present invention, but the present invention is not limited to the examples described below. The examples will be explained using a case where limestone containing CaCO3 as the main component is used as the raw material, and quicklime, which is CaO, is produced as the product. In the examples, the laser beam diameter refers to the diameter of the laser beam at the surface of the raw material in the cylindrical container. [Example 1] Comparison of firing amounts when the surface of the raw material is fired versus when the inside of the raw material is fired. Raw material: Granular limestone, 0.8 mm in size Laser Oscillator: Single-mode fiber laser (wavelength 1090nm, output 80W) Surface firing conditions: Limestone: 0.4g, laser beam diameter: 2.2mm, irradiation time: 210 seconds, firing while vibrating with a vibrator and emitting light (no holes are formed). Internal firing conditions: Limestone: 4.0g (in a test tube, 30mm high), laser beam diameter: 0.55mm (diameter on the surface of the raw material in the cylindrical container), firing in a luminous state while creating holes in the limestone raw material by irradiation for 180 seconds, followed by stirring for 30 seconds, repeated 6 times (total laser irradiation time 1080 seconds), firing the entire raw material. The irradiation time for surface firing and the number of repetitions for internal firing were determined when the residual CO2 content of the product fell below 2.0%, which was considered the target value achieved.

[0036] These results show that the amount of sintered per second of laser irradiation was 1.9 mg / s under surface sintering conditions, compared to 3.7 mg / s under internal sintering conditions. In other words, as shown in the graph in Figure 3, it was found that the sintering efficiency was twice as good under internal sintering conditions compared to surface sintering conditions.

[0037] [Example 2] Firing of the inside of the raw material by laser light irradiation Raw material: Cylindrical limestone measuring 10mm in diameter and 30mm in height Laser Oscillator: Single-mode fiber laser (wavelength 1090nm, output 80W) Laser beam diameter: 0.55 mm (diameter at the surface of the raw material in the cylindrical container)

[0038] Figure 4(a) shows the process of firing a cylindrical limestone raw material 6 by irradiating it with laser light from above to form holes H and cause it to emit light. Figure 4(b) is a vertical cross-section of the limestone in Figure 4(a), illustrating its size. A laser beam was shone from the top of a cylindrical limestone raw material 6 for 10 seconds, and the cross-section of the limestone was observed. As can be seen in Figure 5(a), the limestone was fired by the laser beam, and a concave hole (sinkhole) H was formed from the top surface downwards, and it was fired to a depth of 13.3 mm and a width of 1.4 mm. Similarly, the cross-section of the limestone after laser irradiation for 20 seconds was observed. As can be seen from Figure 5(b), with an irradiation time of 20 seconds, the holes H in the limestone were further sintered than with an irradiation time of 10 seconds, and the sintered area expanded to a range of 13.8 mm in depth and 2.3 mm in width. These results show that, upon laser irradiation, a sinkhole H is formed in the raw material 6, which is made of limestone, at the irradiated site for a certain period of time (10 to 20 seconds in Example 2). Furthermore, the hole H is excavated in the depth direction, and the firing range remains in a wedge shape along the inner circumference ha of the hole H. In Figure 5(b), it is thought that the raw material 6 has just begun to emit light and is in the process of transforming into a heat source as described below.

[0039] Furthermore, the internal firing range was observed by observing the cross-section of the limestone at irradiation times of 150 seconds and 600 seconds. As can be seen from Figure 5(c), it was found that at an irradiation time of 150 seconds, not only the material on the inner circumference ha of the sinkhole but also the material on the outer circumference hb of the sinkhole was fired. Furthermore, as can be seen from Figure 5(d), it was found that at an irradiation time of 600 seconds, the firing range was deeper and wider than at an irradiation time of 150 seconds. From this, it was found that when the laser light irradiation time is continued, the material 6 made of limestone inside the hole H is not only fired directly by the laser light, but the material 6 becomes luminous, generating a heat source inside the hole, and the firing range expands radially to the outer circumference hb of the inner circumference ha of the hole H.

[0040] [Example 3] The effects of heat-shielding and heat-insulating materials Raw material: Granular limestone, 0.8 mm in size Laser Oscillator: Single-mode fiber laser (wavelength 1090nm, output 80W) Laser beam diameter: 0.55 mm (diameter at the surface of the raw material in the cylindrical container) The differences in the calcination reaction were evaluated by the amount of residual CO2 in the resulting product under the following conditions, with an irradiation time of 300 seconds: (1) a cylindrical container filled with raw materials alone, (2) the outer surface of the cylindrical container covered with insulating material, (3) the outer surface of the cylindrical container covered with heat-shielding material, and (4) the outer surface of the cylindrical container covered with heat-shielding material, with the outer surface of the heat-shielding material covered with insulating material.

[0041] [Table 1]

[0042] The purity of quicklime (CaO), a by-product, is considered higher the less CO2 remains. Therefore, the results in this table show that using insulating or heat-shielding materials increases the efficiency of the calcination reaction and reduces the amount of CO2 remaining. Furthermore, it was found that heat-shielding materials resulted in a more efficient calcination reaction than insulating materials, and that the most efficient calcination reaction was achieved when insulating and heat-shielding materials were used together. In other words, the amount of CO2 remaining was reduced most effectively when insulating and heat-shielding materials were used together.

[0043] [Example 4] Laser beam focal length and quicklime production Raw material: Granular limestone, 0.8 mm in size Laser Oscillator: Single-mode fiber laser (wavelength 1090nm, output 80W) Laser beam diameter: 0.55 mm (diameter at the surface of the raw material in the cylindrical container) When using a focusing lens, the ease with which laser light is absorbed due to differences in the numerical aperture (NA) of the lens was confirmed by examining the calcination range of quicklime. Furthermore, this trend can be rephrased as being similar for differences in the focal length (f) of the lens. In the cases of NA=0.045 (f=60mm), NA=0.018 (f=150mm), and NA=0.009 (F=300mm), the raw material 6 in the cylindrical container 2 was irradiated with laser light in the manufacturing apparatus 1 of the present invention, with irradiation times of 150 seconds, 300 seconds, and 600 seconds, respectively. After irradiation was completed, the cylindrical container 2 was cut, and the calcined area of ​​the quicklime in the container 2 was confirmed from the cut surface.

[0044] In the photograph in Figure 6, a hole H is formed in the center of the limestone raw material. The white discolored areas in the inner circumference ha and the outer circumference hb are the fired areas, while the gray dark areas are the unfired areas. As is clear from Figure 6, when the irradiation time was 150 seconds, there was no significant difference in the fired range in the depth direction (same direction as the laser beam irradiation direction) depending on the numerical aperture. However, when the irradiation time was extended to 300 seconds and 600 seconds, a tendency was observed for the fired range to increase in the depth direction as the numerical aperture decreased (increased focal length). In the case of NA=0.045 (f=60mm), even when the irradiation time was extended to 150 seconds, 300 seconds, and 600 seconds, there was not much difference in the fired range in the depth direction. However, in the cases of NA=0.018 and 0.009 (f=150mm and 300mm), a tendency was observed for the fired range to increase in the depth direction as the irradiation time increased. This trend was also confirmed in the graph in Figure 7. Furthermore, a tendency was observed for the firing range to increase in the depth direction with longer focal lengths. This is presumed to be because, with longer focal lengths, the angle of spread of the area (power density) hit by the laser light is smaller, and the heat generated by the absorption of the laser light is more easily transferred in the depth direction. Furthermore, when the irradiation time was 150 seconds, a larger numerical aperture tended to result in a larger firing range in the radial direction of the cylindrical container perpendicular to the irradiation axis of the laser beam. This trend was also confirmed in the graph in Figure 8. This is presumed to be because, as the focal length decreases, the amount of laser light absorbed at a certain depth increases for short durations, and the heat transfer rate in the width direction increases.

[0045] Based on these trends, it is thought that by adjusting the distance between the laser beam's focal point and the surface of the raw material, as well as the diameter and height of the cylindrical container, it is possible to select the optimal configuration for firing all of the raw material inside the cylindrical container into the final product using the laser beam. In other words, if you want to expand the firing range radially at a shallow position in the raw material, it is preferable to use a focusing lens with a large NA (short f). On the other hand, by using a focusing lens with a small numerical aperture (long f), it is possible to generate a heat source through light emission at a deep position. Therefore, if the laser beam irradiation time is sufficiently long, it should be possible to sinter a wide area at once.

[0046] [Other embodiments of the manufacturing apparatus 1 of the present invention] If the discharge section 4 of the manufacturing apparatus 1 of the present invention is a shutter, the opening and closing mechanism 41 of the discharge section 4 may have a structure consisting of two overlapping sliding plates (sliding plates 41a and 41b) with discharge holes, as shown in Figure 12(a). The opening and closing mechanism 41 may also be a mechanism in which, as shown in Figure 12(b), the sliding plate 41a moves to the right, the discharge hole 411a in the sliding plate 41a and the discharge hole 411b in the sliding plate 41b below it overlap, opening the shutter, the product 8 is discharged as shown in Figure 12(c), and the shutter closes as the sliding plate 41a returns to the left, as shown in Figure 12(d). [Explanation of Symbols]

[0047] 1. Manufacturing apparatus of the present invention 2. Cylindrical container 21 Peripheral wall 22 Top 23 Bottom end 24 Reaction space 25. Heat shielding material for the lid 251 Translucent part 26. Side heat shielding material 27. Side panel insulation 28 Heat-shielding material holding section 3 Raw material supply department 31 Hopper 32 Rohto 33 Connecting pipe 34 Raw material discharge port 4 Discharge section 41 Opening and closing mechanism 41a Slide plate 411a Ejection hole 41b Slide plate 411b Ejection hole 42 Shutter holding part 5. Laser beam irradiation area 51 Laser light 52 Focusing lens 6 Raw materials H hole (sunken hole) ha Inner circumference 7 Cooling section 71 Lower insulation 72 Heatsink 73 Outlet 8 products

Claims

1. A method for obtaining a product containing the corresponding Ca and / or Mg oxide from a raw material containing Ca and / or Mg carbonate or Ca and / or Mg hydroxide, (Step 1) A step of irradiating the raw material with laser light to form a hole in the area irradiated with laser light; (Step 2) A step in which the raw material on the inner circumference of the hole is fired by irradiation with laser light; (Step 3) A step of increasing the temperature of the inner circumference by further irradiation with laser light, causing the inner circumference to emit light; and (Step 4) A step in which the raw material at the periphery of the inner circumference is fired by thermal radiation from the inner circumference in the state described above. A method for producing oxides of Ca and / or Mg, including the aforementioned method.

2. A method for producing Ca and / or Mg oxides according to claim 1, comprising step 5 of discharging the product containing Ca and / or Mg oxides generated by the calcination in steps 2 and 4, and adding new raw materials.

3. A cylindrical container having a peripheral wall and upper and lower ends, for holding a raw material containing a carbonate of Ca and / or Mg or a hydroxide of Ca and / or Mg, A raw material supply unit for supplying raw materials from the upper end of the cylindrical container, A discharge section is installed on the lower side of the lower end of the cylindrical container, An apparatus for obtaining a product containing the corresponding Ca and / or Mg oxide from the raw materials, including the above, A laser beam irradiation unit is installed on the upper side of the upper end of the cylindrical container, The cylindrical container is provided with a light-transmitting section at the top that allows the laser light emitted from the laser light irradiation section to pass through to the inside of the cylindrical container, The inside of the cylindrical container constitutes a reaction space that generates the product formed by firing the raw material filled inside the container upon irradiation with the laser light. The discharge section includes a mechanism that can control the stopping and starting of the discharge of the product from the lower end of the cylindrical container. An apparatus for producing Ca and / or Mg oxides, characterized by the features described above.

4. The manufacturing apparatus according to claim 3, characterized in that a concave hole is formed on the surface of the raw material filled inside the cylindrical container.

5. The manufacturing apparatus according to claim 3 or 4, characterized in that the cylindrical container is covered with a heat-shielding material and / or an insulating material.

6. The manufacturing apparatus according to claim 3 or 4, wherein a focusing lens is installed between the cylindrical container and the laser light irradiation unit.

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