Method for extracting ferrite, method for producing ferrite, and apparatus for producing ferrite

Abstract

This method for extracting ferrite includes: irradiating a material of interest with microwaves that are in a steady state for magnetically heating the material of interest, thereby producing ferrite; and eluting the ferrite to extract the ferrite. The material of interest is preferably a nickel-containing ore. The material of interest is preferably disposed at a position where magnetic field strength is relatively high. According to the present invention, provided are: a method for extracting ferrite, with which it is possible to extract ferrite at a low temperature, in a short time, and under ambient pressure through a simple work process with a low environmental load; a method for producing ferrite, with which it is possible to produce ferrite at a low temperature, in a short time, and under ambient pressure through a simple work process with a low environmental load; and an apparatus for producing ferrite, which has a simple configuration and a low environmental load and with which it is possible to produce ferrite at a low temperature, in a short time, and under ambient pressure.

Description

Ferrite extraction method, ferrite manufacturing method, and ferrite manufacturing device

[0001] The present invention relates to a method for extracting ferrite, a method for producing ferrite, and an apparatus for producing ferrite.

[0002] Conventionally, in the smelting of Mn, Co, Ni, Mg, or Cu, a dry process involves adding a reducing agent such as coal (carbon) to a material containing Mn, Co, Ni, Mg, or Cu and iron, for example, industrial waste, soil, or ore, and melting the material at high temperatures of 900°C to 1400°C in an electric furnace (for example, a rotary kiln) for a long period of time (pyrometallurgy), while a wet process involves leaching using a highly concentrated acid or performing a long-term reaction at high temperatures and pressures of 200°C or higher and 3 MPa or higher in an autoclave charged with a highly concentrated acid (high-pressure acid leaching) (see, for example, Patent Document 1).

[0003] However, conventional refining methods have become a major social problem due to the poor working conditions at the work site, which can cause health problems for workers, and the release of environmentally destructive gases such as carbon dioxide during the work.

[0004] Japanese Patent Application Laid-Open No. 2021-176985

[0005] The objects of the present invention are to provide a method for extracting ferrite that allows for the extraction of ferrite at low temperature, in a short time, and at normal pressure using simple work steps that place little strain on the environment; to provide a method for producing ferrite that allows for the production of ferrite at low temperature, in a short time, and at normal pressure using simple work steps that place little strain on the environment; and to provide a ferrite production apparatus that has a simple configuration and allows for the production of ferrite at low temperature, in a short time, and at normal pressure using simple work steps that place little strain on the environment.

[0006] The above object can be achieved by the present invention, which is described below. In the method for extracting ferrite of the present invention, a material to be treated is irradiated with microwaves in a steady state to generate ferrite by magnetic heating, and the ferrite is then extracted by elution.

[0007] In the ferrite extraction method of the present invention, the material to be treated is preferably a nickel-containing ore.

[0008] In the ferrite extraction method of the present invention, the material to be treated is preferably placed in a position where the magnetic field strength is relatively strong.

[0009] In the ferrite extraction method of the present invention, it is preferable that the treated material is heated by the microwave irradiation to a temperature of 0.7 × Tc [°C] or more and 1.3 × Tc [°C] or less, where Tc [°C] is the Curie temperature of the ferrite.

[0010] In the ferrite extraction method of the present invention, the microwave frequency is preferably 0.9 GHz or more and 30 GHz or less.

[0011] In the ferrite extraction method of the present invention, it is preferable to perform a heat treatment and / or a magnetic field application treatment in which an external magnetic field is applied as a pretreatment to the material to be treated before the microwave irradiation.

[0012] In the ferrite extraction method of the present invention, it is preferable that the pretreatment heats the treated material to a temperature less than 0.7×Tc [°C], where Tc [°C] is the Curie temperature of the ferrite.

[0013] In the ferrite extraction method of the present invention, it is preferable that, when irradiating the microwaves, a magnetic field application process is further performed in which the magnetic field intensity of the external magnetic field is swept in a direction perpendicular to the magnetic field component of the microwaves.

[0014] In the ferrite extraction method of the present invention, when irradiating the microwaves, it is preferable to further perform the magnetic field application process in which a steady magnetic field having a constant magnetic field strength and a direction perpendicular to the magnetic field component of the microwaves is applied as the external magnetic field.

[0015] The method for producing ferrite of the present invention includes the method for extracting ferrite of the present invention.

[0016] The ferrite manufacturing apparatus of the present invention includes a processing chamber in which a processing object is placed, a microwave irradiation means for irradiating the processing object placed in the processing chamber with steady-state microwaves to magnetically heat the processing object, and an external magnetic field application means for applying an external magnetic field to the processing object.

[0017] The ferrite manufacturing apparatus of the present invention preferably further comprises an external heating means for heating the material to be treated in addition to the magnetic heating.

[0018] The ferrite manufacturing apparatus of the present invention preferably includes a metallic movable short-circuit plate disposed within the processing chamber, and by moving the movable short-circuit plate, the phase of the incident wave incident into the processing chamber from the microwave irradiation means and the phase of the reflected wave reflected by the movable short-circuit plate are adjusted.

[0019] According to the present invention, it is possible to provide a ferrite extraction method that allows ferrite to be extracted at low temperature, in a short time, and at normal pressure using simple work steps that have little impact on the environment; to provide a ferrite production method that allows ferrite to be produced at low temperature, in a short time, and at normal pressure using simple work steps that have little impact on the environment; and to provide a ferrite production device that has a simple configuration that allows ferrite to be produced at low temperature, in a short time, and at normal pressure using little impact on the environment.

[0020] FIG. 1 is a diagram schematically showing an example of the configuration of a ferrite manufacturing apparatus of the present invention. FIG. 2 is a diagram schematically showing the relationship between an external magnetic field and the electric field component and magnetic field component of microwaves in the manufacturing apparatus shown in FIG. 1. FIG. 3 is a diagram schematically showing the relationship between microwave irradiation time and temperature when a heat treatment is performed on the material to be treated as a pretreatment before microwave irradiation. FIG. 4 is a diagram schematically showing the relationship between microwave irradiation time and temperature when a magnetic field application treatment is performed on the material to be treated as a pretreatment before microwave irradiation. FIG. 5 is a diagram schematically showing the relationship between microwave irradiation time and temperature when an external magnetic field is further applied and the magnetic field strength is swept when irradiating microwaves to the material to be treated. FIG. 6 is a diagram schematically showing the relationship between microwave irradiation time and temperature when a constant magnetic field strength and a steady magnetic field perpendicular to the microwave magnetic field component are further applied when irradiating microwaves to the material to be treated. FIG. 7 is an XRD pattern for the solid solution obtained in Example 1. FIG. 8 is an XRD pattern for the solid solution obtained in Example 2. FIG. 9 is an XRD pattern for the solid solution obtained in Example 3. FIG. 10 is an XRD pattern for the solid solution obtained in Example 4. FIG. 11 is an XRD pattern for the solid solution obtained in Example 5. FIG. 12 is an XRD pattern for the solid solution obtained in Example 6. FIG. 13 is a diagram showing the ratio of solid solution to residual powder when the microwave heating temperature is changed. FIG. 14 is an XRD pattern for the solid solutions obtained in Examples 7 to 9. FIG. 15 is an XRD pattern for the solid solution obtained in Example 10. FIG. 16 is an XRD pattern for the solid solution obtained in Example 11. FIG. 17 is an XRD pattern for the solid solution obtained in Example 12. FIG. 18 is an XRD pattern for the solid solution obtained in Example 13. FIG. 19 is a diagram showing the change over time in temperature of a nickel-containing ore that was subjected to a heat treatment as a pretreatment and then irradiated with microwaves. Fig. 20 is a graph showing the temperature change over time of a nickel-containing ore that has been subjected to an external magnetic field as a pretreatment and then irradiated with microwaves. Fig. 21 is a graph showing the temperature change over time of a nickel-containing ore that has been irradiated with microwaves and an external magnetic field (steady magnetic field) applied.FIG. 22 is a diagram showing the change in temperature of nickel-containing ore over time when an external magnetic field is swept while microwaves are irradiated.

[0021] Preferred embodiments of the present invention will be described in detail below.

[0022] [1] Ferrite Extraction Method First, the ferrite extraction method of the present invention will be described. In the ferrite extraction method of the present invention, a material to be treated is irradiated with microwaves in a steady state to generate ferrite by magnetic heating, and the ferrite is then extracted by elution.

[0023] In the present invention, ferrite is generated in the material to be treated by magnetic heating by irradiating the material with steady-state microwaves. Then, by selectively and internally heating the generated ferrite, it is possible to elute the target ferrite from the material to selectively extract it. Although the mechanism of ferrite generation by magnetic heating is unclear, it is presumed that the magnetic ion-containing oxide in the mixture is locally heated by magnetic heating, causing the coordinated hydrates and the like to thermally decompose, changing its structure, and then the ferrite is generated by a solid-phase reaction caused by magnetic heating.

[0024] In the present invention, the produced ferrite is selectively heated from the inside, which allows for refining at a lower temperature in a shorter time and with a simpler process than external heating without using microwaves. Furthermore, since there is no need to use an autoclave or the like using an acid solvent, heating can be performed at normal pressure without requiring high pressure.

[0025] As described above, the present invention can provide a method for extracting ferrite that is capable of extracting ferrite at low temperature, in a short time, and under normal pressure using simple working steps that place little strain on the environment.

[0026] Furthermore, according to the ferrite extraction method of the present invention, ferrite containing the target metal element (metal element other than iron) as a constituent element can be obtained efficiently at low cost even from a treated material having a relatively low content of the target metal element. Therefore, ferrite containing the target metal element can be suitably obtained from a treated material having a low content of the target metal element, which has not been used in the past. Therefore, it is expected that the amount of metal resources available to humanity will increase significantly in the future.

[0027] In the present invention, the term "ferrite" refers to a magnetic oxide mainly composed of iron oxide. Examples of ferrite include those having a spinel type, magnetoplumbite type, and ferroxplanar type structure, but are not particularly limited thereto.

[0028] In addition, in the present invention, the term "steady state" refers to a state in which microwaves, which are electromagnetic waves, are standing waves. In a standing wave, the incident wave and the reflected wave are superimposed, and therefore the wave energy is amplified.

[0029] In the present invention, "magnetic heating" refers to a heating mechanism that occurs when a magnetic material such as ferrite interacts with microwaves. Specifically, "magnetic heating" refers to magnetic hysteresis heating, eddy current heating, or heating that utilizes a resonance phenomenon (resonance heating). In the following explanation, these types of heating may be collectively referred to as "magnetic heating."

[0030] [1-1] Treated Material In the present invention, selective extraction is achieved by applying magnetic heating by microwave irradiation to provide the energy necessary to reach the Curie temperature of the component to be extracted contained in the treated material (in other words, the target ferrite produced by magnetic heating by microwave irradiation).

[0031] Therefore, the method of the present invention can be applied to a processed material from which a ferrite having a Curie temperature Tc is obtained as an extract. The Curie temperature Tc is the transition temperature at which a ferromagnetic material changes into a paramagnetic material.

[0032] The material to be treated is not particularly limited as long as it generates ferrite by magnetic heating due to microwave irradiation, but for example, a material containing iron and a metal element other than iron can be used.

[0033] Examples of metal elements other than iron include Cr, Mn, Co, Ni, Mg, Cu, and rare earth elements (Sc, Y, and lanthanoids).

[0034] Of the above, the material to be treated preferably contains Cr, Mn, Co, Ni, Mg or Cu and iron, and more preferably contains Ni and iron, or Mn and iron.

[0035] The material to be treated is preferably a nickel-containing ore, which makes the effects of the present invention more pronounced.

[0036] In this specification, nickel-containing ore refers to ore containing nickel and iron.

[0037] From such nickel-containing ores, for example, NiFe as ferrite can be obtained. ２ O ４ can be extracted.

[0038] The nickel-containing ore may contain nickel and iron, but may also contain other elements, such as rare earth elements.

[0039] Usually, the content of rare earth elements in nickel-containing ores is extremely small. However, according to the extraction method of the present invention, the main target product, ferrite NiFe, ２ O ４ and RFe containing rare earth elements. ２ O ４ A solid solution containing rare earth elements (R: rare earth elements) as a by-product can be obtained as an extract. In particular, rare earth elements contained in nickel-containing ore can be contained in the extract with a high recovery rate. Therefore, by further refining the extract, high-purity NiFe ２ O ４(or Fe, Ni as simple metals) and high-purity rare earth elements can be obtained.

[0040] As described above, the nickel-containing ore to be treated generates ferrite when irradiated with microwaves in a steady state. The components that serve as raw materials for ferrite contained in the nickel-containing ore include, for example, (Ni, Mg) ３ Si ２ O ５ (OH) ４ (Serpentine), FeOOH (Goethite), (Fe, Mg) ３ Si ２ O ５ (OH) ４ Examples of suitable oxides include lizardite.

[0041] The nickel-containing ore may also contain oxides other than those mentioned above. Examples of such oxides include ferrite (FeNi ２ O ４ ), silicon oxide (alpha-SiO ２ Ferrite can be dissolved and extracted by magnetic heating.

[0042] In addition to nickel-containing ores, other materials that can be used for processing include, for example, chromium-containing ores containing chromium and iron, manganese-containing ores containing manganese and iron, cobalt-containing ores containing cobalt and iron, magnesium-containing ores containing magnesium and iron, and copper-containing ores containing copper and iron.

[0043] Specifically, manganese-containing ore containing chromium and iron produces ferrite, such as CrFe. ２ O ４ and Cr ２ FeO ４ can be extracted.

[0044] In addition, manganese-containing ores containing manganese and iron produce ferrite such as MnFe. ２ O ４ and Mn ２ FeO ４can be extracted.

[0045] Cobalt-containing ore containing cobalt and iron produces ferrite, such as CoFe. ２ O ４ YaCo ２ FeO ４ can be extracted.

[0046] In addition, magnesium-containing ore containing magnesium and iron produces ferrite such as MgFe. ２ O ４ and Mg ２ FeO ４ can be extracted.

[0047] Also, from copper-containing ores containing copper and iron, ferrite such as CuFe ２ O ４ and Cu ２ FeO ４ can be extracted.

[0048] As with nickel-containing ores, these ores have conventionally been subjected to smelting processes that place a heavy burden on the environment. Therefore, according to the present invention, ferrite containing these metals can also be extracted at low temperature, in a short time, and at normal pressure using a simple process that places a low burden on the environment.

[0049] Furthermore, like the nickel-containing ores described above, these ores also usually contain very small amounts of rare earth elements. According to the extraction method of the present invention, rare earth elements can be efficiently extracted from these ores, and high-purity CrFe ore can be obtained by subsequent processing. ２ O ４ , Cr ２ FeO ４ , MnFe ２ O ４ , Mn ２ FeO ４ , CoFe ２ O ４ , Co ２ FeO ４ , MgFe ２ O ４ , Mg ２ FeO ４ , CuFe ２ O ４, Cu ２ FeO ４ (or Fe, Cr, Mn, Co, Mg, Cu as simple metals) and high-purity rare earth elements can be obtained with a high recovery rate. ２ FeO ４ (where M in the formula is a metal element other than Fe), is generally advantageous in that a metal more expensive than iron can be efficiently obtained.

[0050] The shape of the treated material is not particularly limited, but is preferably in a particulate (powder) form, which allows the treated material to more suitably absorb microwaves and more suitably promote the production of the target ferrite and the magnetic heating and elution of the target ferrite.

[0051] In the following description, the material to be treated is a nickel-containing ore containing nickel and iron, and NiFe is extracted as ferrite from the material. ２ O ４ The following mainly describes the case where NiFe is extracted. ２ O ４ is a ferrite having a typical spinel-type crystal structure.

[0052] [1-2] Ferrite Manufacturing Apparatus The ferrite manufacturing apparatus of the present invention used in the ferrite extraction method of the present invention will be described below. Figure 1 is a diagram schematically showing one example of the configuration of the ferrite manufacturing apparatus of the present invention.

[0053] The ferrite manufacturing apparatus 1 comprises a processing chamber 10 in which the processing object 20 is placed, a microwave irradiation means 11 that irradiates the processing object 20 placed in the processing chamber 10 with steady-state microwaves to magnetically heat the processing object 20, and an external magnetic field application means 14 that applies an external magnetic field to the processing object 20.

[0054] In the ferrite manufacturing apparatus 1, ferrite is generated in the processing material 20 by magnetic heating caused by irradiating the processing material 20 with steady-state microwaves, and the ferrite generated in the processing material 20 is selectively heated from the inside to be dissolved, thereby making it possible to selectively extract the desired ferrite.

[0055] As described above, the present invention can provide a ferrite manufacturing apparatus 1 that has a simple structure with little environmental impact and is capable of performing extraction at low temperature, in a short time, and under normal pressure.

[0056] Furthermore, according to the ferrite manufacturing apparatus of the present invention, ferrite containing a target metal element (a metal element other than iron) as a constituent element can be obtained efficiently at low cost even from a treated material having a relatively low content of the target metal element. Therefore, ferrite containing the target metal element can be suitably obtained from a treated material having a low content of the target metal element, which has not been used in the past. Therefore, it is expected that the amount of metal resources available to humanity will increase significantly in the future.

[0057] In the following explanation, the ferrite manufacturing apparatus 1 will be mainly described as a single-mode type that irradiates microwaves in a single mode, but the ferrite manufacturing apparatus 1 of the present invention may also be a multi-mode type apparatus that irradiates microwaves in multiple modes.

[0058] The processing chamber 10 has a hollow box shape. The processing object 20 is placed in the processing chamber 10.

[0059] The outer wall of the processing chamber 10 is made of a material such as copper or aluminum, and the inner surface is plated with silver, gold, etc., and has microwave reflectivity. The shape, size, etc. of the processing chamber 10 are determined depending on, for example, the distribution of microwaves irradiated onto the processing object 20.

[0060] It is preferable that the processing chamber 10 has a closed structure to prevent leakage of microwaves, except for portions that require openings, such as an entrance and exit for the processing object 20. The processing chamber 10 may also be provided with an observation window (not shown) for observing the interior, and a ventilation hole or fan (not shown) for supplying and exhausting air.

[0061] The microwave irradiation means 11 includes a microwave oscillator and irradiates the inside of the processing chamber 10 with microwaves.

[0062] The microwave oscillator oscillates microwaves at a predetermined frequency. The microwave oscillator may include, for example, a variable frequency oscillator and a variable amplifier (not shown). The variable frequency oscillator is configured to be able to output microwaves with a variable frequency. The variable amplifier amplifies the power of the microwaves output from the variable frequency oscillator.

[0063] 1 includes a metallic movable short-circuit plate 13 disposed in a processing chamber 10. By moving the movable short-circuit plate 13 in the processing chamber 10 in the x-axis direction in the figure, the phase of the incident wave incident into the processing chamber 10 from the microwave irradiation means 11 and the phase of the reflected wave reflected by the movable short-circuit plate 13 can be adjusted.

[0064] Specifically, for example, the phase of the incident wave incident into the processing chamber 10 from the microwave irradiation means 11 and the phase of the reflected wave reflected by the movable short-circuit plate 13 are made to coincide with each other.

[0065] An iris 12 may be provided as an opening in the side wall of the processing chamber 10, which serves as an inlet for microwaves from the microwave irradiation means 11 to the processing chamber 10. This iris 12 has the function of passing incident waves that are incident into the processing chamber 10 from the microwave irradiation means 11 and returning reflected waves reflected by the movable short-circuit plate 13 back into the processing chamber 10.

[0066] FIG. 1 also shows an image of a standing microwave wave in the ferrite manufacturing apparatus 1.

[0067] The electric field component of the microwave (E ｍｗ ) and the magnetic field component (H ｍｗ ) is perpendicular to the direction of the electric field component (E ｍｗ ) is parallel to the paper surface (in-plane direction), and the magnetic field component of the microwave (H ｍｗ ) is oriented perpendicular to the paper surface (depth direction).

[0068] In this specification, "perpendicular" does not mean "perpendicular" in the strict mathematical sense, but allows for a slight deviation.

[0069] In this specification, "parallel" does not mean "parallel" in the strict mathematical sense, but allows for a slight deviation.

[0070] The microwaves (wavelength) incident from the microwave irradiation means 11 are blocked by the movable short-circuit plate 13 (x = L) at the microwave outlet, and the microwaves that are not irradiated to the object to be treated 20 are reflected, and the reflected waves are re-irradiated to the object to be treated 20, pass through, and return to the microwave irradiation means 11.

[0071] Here, an iris 12 is provided between the object to be processed 20 and the microwave irradiation means 11, which allows the incident wave to pass through and returns the reflected wave, so that the incident wave is confined to this space and enters a resonant state (L = nλ / 2; n = 1, 2, 3, ...). In other words, the phase of the incident wave and the phase of the reflected wave are aligned, and a standing wave with amplified energy is generated.

[0072] By using this standing wave, by placing the object to be treated 20 in a position where the microwave energy is relatively large, it becomes possible to irradiate the object to be treated 20 with microwaves having greater energy than the energy of the incident wave, thereby enabling efficient magnetic heating of the object to be treated 20.

[0073] The external magnetic field applying means 14 applies an external magnetic field to the processing object 20 disposed in the processing chamber 10. The external magnetic field applying means 14 includes, for example, an electromagnet. The external magnetic field generated by the electromagnet is a DC magnetic field.

[0074] Prior to irradiating the object 20 with microwaves, the object 20 can be pre-treated by applying an external magnetic field by the external magnetic field application means 14. Furthermore, when the object 20 is heated by microwaves, the object 20 can be magnetically heated more efficiently by applying an external magnetic field by the external magnetic field application means 14.

[0075] Installation location x of external magnetic field application means 14 ａ For example, the position of the maximum electric field is E ｍａｘ． The position of the maximum magnetic field is H ｍａｘ． As E ｍａｘ． −λ / 2≦x ａ ≦H ｍａｘ．The position satisfies +λ / 2.

[0076] In this specification, "maximum" does not mean "maximum" in the strict mathematical sense, but rather allows for some deviation.

[0077] The ferrite manufacturing apparatus 1 shown in FIG. 1 further includes an external heating means 15 for heating the object 20 to be processed in addition to magnetic heating.

[0078] The external heating means 15 includes a heating element, and this heating element externally heats the object to be treated 20. The heating element included in the external heating means 15 is, for example, an electric heater.

[0079] Prior to microwave heating of the object 20 to be treated, the object 20 to be treated can be pretreated by external heating using the external heating means 15. This provides the effects described below.

[0080] Installation location x of external heating means 15 ｂ For example, E ｍａｘ． −λ / 2≦x ｂ ≦H ｍａｘ． The position satisfies +λ / 2.

[0081] The ferrite manufacturing apparatus 1 shown in FIG. 1 further includes a radiation thermometer 16 for measuring the temperature of the object to be irradiated, and a gaussmeter 17 for measuring the magnitude of the external magnetic field.

[0082] The radiation thermometer 16 measures the temperature of the irradiated object, that is, the processing object 20. The gauss meter 17 has a gauss element disposed at the center of the pole piece of the electromagnet provided in the external magnetic field application means 14, and measures the magnitude of the external magnetic field.

[0083] The ferrite manufacturing apparatus 1 also includes a control unit 18 that controls the operations of the external magnetic field applying means 14 , the external heating means 15 , and the movable short-circuit plate 13 in accordance with the results of measurements by the radiation thermometer 16 and the gaussmeter 17 .

[0084] In such a single-mode device, the electric field component (E ｍｗ ) and magnetic field component (H ｍｗ) and the metal plate (movable short-circuit plate 13) have different reflection characteristics. ｍａｘ． ) and the position of the maximum magnetic field (H ｍａｘ． ) and λ / 4 (= |E ｍａｘ． -H ｍａｘ． A major feature is that the images are generated with a shift of just |.

[0085] The object to be processed 20 is mainly placed at a position where the magnetic field strength is relatively strong, indicated by g in FIG.

[0086] As will be described later in detail, in this specification, the term "position where the magnetic field strength is relatively strong" refers to the position where the magnetic field strength is at its maximum (H ｍａｘ． ) at ±λ / 8 positions.

[0087] [1-3] Pretreatment It is preferable to pretreat the material to be treated before irradiating it with microwaves, which allows for more efficient magnetic heating by microwave irradiation.

[0088] Examples of the pretreatment include a heat treatment and / or a magnetic field application treatment in which an external magnetic field is applied.

[0089] By performing a heat treatment as a pretreatment, functional groups contained in the treated material, such as hydroxyl groups, are eliminated, facilitating magnetic heating by microwave irradiation. Furthermore, magnetic heating by microwave irradiation in a subsequent step is performed more efficiently, and the temperature of the treated material rises more quickly, allowing it to reach a target temperature (e.g., the Curie temperature Tc) more quickly.

[0090] Furthermore, by performing a magnetic field application process as a pretreatment, the magnetic hysteresis of the ferrite contained in the material to be treated is expanded, facilitating magnetic heating by microwave irradiation. Furthermore, magnetic heating by microwave irradiation in the subsequent process is performed more efficiently, and the temperature of the material to be treated rises more quickly, allowing it to reach a target temperature (e.g., the Curie temperature Tc) more quickly.

[0091] When a magnetic field application process is performed as a pretreatment to apply an external magnetic field, the direction of the external magnetic field is not particularly limited, and may be, for example, perpendicular or parallel to the magnetic field component of the microwave.

[0092] 2 shows the manufacturing apparatus shown in FIG. 1 in which an external magnetic field (H ｅｘ． ) and the electric field component of the microwave (E ｍｗ ) and magnetic field components (H ｍｗ ) is a diagram showing a schematic relationship between the

[0093] The pretreatment may be either a heat treatment or a magnetic field application treatment, or both. When both a heat treatment and a magnetic field application treatment are performed, the treatments may be performed simultaneously or sequentially. When the treatments are performed sequentially, the order is not particularly limited.

[0094] [1-3-1] Heat Treatment as Pretreatment Heat treatment as pretreatment for the object to be treated 20 is not particularly limited, but for example, external heating by the external heating means 15, electric field component (E ｍｗ ) heating, for example, treatment by dielectric heating or Joule heating.

[0095] 3 is a diagram showing the relationship between microwave irradiation time and temperature when the object to be treated is subjected to a heat treatment as a pretreatment before microwave irradiation. The temperature T of the object to be treated 20 is a value measured using a radiation thermometer 16.

[0096] Depending on the temperature T of the pre-processed material, the magnetic field component (H ｍｗ In other words, the higher the temperature of the object to be treated by pretreatment, the longer the time it takes to reach the target temperature (for example, the Curie temperature Tc) by magnetic heating (T ２ >T １ >RT), and the time required to reach the target temperature is shortened by magnetic heating using microwave irradiation in a subsequent process. This allows magnetic heating to be performed more efficiently.

[0097] However, once the Curie temperature Tc is reached, the ferrite no longer absorbs microwave energy due to a change in magnetism, and no further temperature rise is observed in the processed material.

[0098] In this way, by changing the temperature of the material to be treated in the heat treatment as a pretreatment, it is possible to control the temperature and time in magnetic heating by microwave irradiation.

[0099] For example, in a ferrite manufacturing apparatus 1 as shown in FIG. 1, in a heating process including a pre-treatment heating treatment and magnetic heating by microwave irradiation, the electric field space and the magnetic field space of the microwave can be selected and used depending on the purpose, thereby easily heating the processing object 20.

[0100] In other words, first, the object 20 to be treated is placed at a position f in the treatment chamber 10 where the electric field strength is relatively strong, and microwaves are irradiated from the microwave irradiation means 11, thereby performing a heating treatment (electric field component E ｍｗ Then, the object 20 is moved from a position f where the electric field strength is relatively strong to a position g where the magnetic field strength is relatively strong (H ｍａｘ． ), irradiating microwaves and magnetically heating the object 20 in an AC magnetic field space, a series of heating processes for the object 20 can be easily carried out in the same processing chamber.

[0101] As mentioned above, the maximum electric field position E ｍａｘ． and the maximum magnetic field position H ｍａｘ． Therefore, when moving from position f where the electric field strength is relatively strong to position g where the magnetic field strength is relatively strong, the object 20 to be processed only needs to be moved by λ / 4.

[0102] [1-3-2] Magnetic Field Application as Pretreatment By applying an external magnetic field to the treated material as a pretreatment, magnetic hysteresis expansion due to the contained nickel is induced.

[0103] As a result, in the subsequent magnetic heating process using microwave irradiation, the temperature of the object to be treated can be raised to a target temperature (for example, Curie temperature T Ｃ ) can be reached.

[0104] External magnetic field (H ｅｘ． ) is, for example, a DC magnetic field generated by an electromagnet provided in the external magnetic field applying means 14.

[0105] FIG. 4 is a diagram showing a schematic diagram of the relationship between microwave irradiation time and temperature when a magnetic field application treatment is performed on the treatment object as a pretreatment before microwave irradiation.

[0106] As a pretreatment, a magnetic field is applied to the treatment object 20 using the external magnetic field application means 14. The magnitude H of the magnetic field applied to the treatment object 20 is ｅｘ． (>0) is a value measured using the Gaussmeter 17. The temperature T of the object 20 to be treated is a value measured using the radiation thermometer 16.

[0107] In a later step, the magnetic field component of the microwave (H ｍｗ ) by irradiating the magnetic field H ｅｘ． In other words, the time required to reach a target temperature (for example, the Curie temperature Tc) varies depending on the magnitude H of the external magnetic field applied to the object to be treated in the pretreatment. ｅｘ The higher the value (H ２ >H １ ), and magnetic heating by microwave irradiation in a subsequent process shortens the time required to reach the target temperature.

[0108] In the pretreatment by applying an external magnetic field, the temperature of the object to be treated does not change substantially, but the magnetic heating by microwave irradiation is efficiently performed, and the gradient of the temperature change increases with the magnitude of the external magnetic field H. ｅｘ． The higher the value, the larger the magnitude.

[0109] However, once the Curie temperature Tc is reached, no further temperature rise is observed in the processed material.

[0110] In this way, by changing the magnetic field strength in the application of an external magnetic field as a pretreatment, it is possible to control the temperature and time in magnetic heating by microwave irradiation.

[0111] In the pretreatment by the heat treatment and / or magnetic field application treatment as described above, when the Curie temperature of the target ferrite is Tc [°C], it is preferable to heat the treated material in the pretreatment to a temperature of less than 0.9 × Tc [°C], more preferably to a temperature of less than 0.8 × Tc [°C], and even more preferably to a temperature of less than 0.7 × Tc [°C].

[0112] This allows magnetic heating by microwave irradiation in a subsequent process to be carried out more efficiently, and the temperature of the object to be treated can reach a target temperature (for example, the Curie temperature Tc) in an even shorter time.

[0113] For example, if the target ferrite is NiFe ２ O ４ In this case, the Curie temperature Tc is 585°C, so it is preferable to heat the treatment object to a temperature of less than 410°C in the pretreatment.

[0114] The pretreatment should raise the temperature of the material to be treated above its original temperature, and the lower limit of the temperature is not particularly limited, but is, for example, room temperature or higher.

[0115] Also, NiFe ２ O ４ Ferrite compounds other than MnFe and their Curie temperatures are, for example, ２ O ４ (T Ｃ :300℃~327℃), CoFe ２ O ４ (T Ｃ :520℃), CuFe ２ O ４ (T Ｃ :490℃), MgFe ２ O ４ (T Ｃ The heating temperature in the pretreatment can be appropriately set depending on the desired ferrite.

[0116] Furthermore, in the pretreatment by heating treatment and / or magnetic field application treatment as described above, the processing time of the pretreatment is not particularly limited as long as it is possible to raise the temperature of the material to the above-mentioned temperature, but it can be, for example, from 1 second to 3600 seconds.

[0117] This allows the pretreatment of the material to be performed more suitably, and the extraction of ferrite according to the present invention can be performed more efficiently.

[0118] [1-4] Magnetic heating by microwave irradiation The material to be treated is irradiated with steady-state microwaves to magnetically heat the material. This generates ferrite in the material to be treated. Furthermore, the ferrite generated in the material to be treated can be selectively heated and eluted by magnetic heating due to microwave irradiation.

[0119] Specifically, for example, when the material to be treated is a nickel-containing ore containing nickel and iron, the components in the nickel-containing ore react with each other by microwave irradiation to form ferrite, such as NiFe. ２ O ４ and a solid solution containing the ferrite is obtained.

[0120] The microwave may be a multi-mode or a single-mode. In the multi-mode, the microwave is irradiated to the object to be processed in random directions and phases, whereas in the single-mode, a resonator is used to separate the microwave, which is an electromagnetic wave, into an electric field component and a magnetic field component, and one of them can be selectively irradiated to the object to be processed.

[0121] In the following description, the case where microwaves are irradiated in a single mode will be mainly described.

[0122] First, the object to be treated 20 is placed in the treatment chamber 10, and then the movable short-circuit plate 13 is moved to adjust the phase of the incident wave incident into the treatment chamber 10 from the microwave irradiation means 11 and the reflected wave reflected by the movable short-circuit plate 13 so as to be aligned.

[0123] This results in a single-mode "steady state" that is a standing wave with more energy than the energy of the incident wave.

[0124] As a result, the object 20 to be treated is heated mainly by magnetic hysteresis heating in the microwave AC magnetic field space, and the temperature rises. The temperature of the object 20 to be treated during microwave heating is measured by a radiation thermometer 16. Furthermore, the magnetic loss (μ') of the object 20 to be treated (nickel-containing ore) changes with the rise in temperature, and therefore needs to be readjusted using the movable short-circuit plate 13.

[0125] The object to be treated 20 is preferably placed in a position in the treatment chamber 10 where the magnetic field strength is relatively strong.

[0126] This allows irradiation with microwave energy greater than the energy of the incident wave, and more suitably performs magnetic heating on the processing object 20. Therefore, additives such as microwave absorbents and catalysts are not required.

[0127] In this specification, the term "position where the magnetic field strength is relatively strong" refers to the position where the magnetic field strength is at its maximum (H ｍａｘ． ) to the position where the electric field strength is maximum (E ｍａｘ． ) and the position where the magnetic field strength is maximum (H ｍａｘ． ) and is defined as the range up to 1 / 2 of λ / 4.

[0128] In other words, as shown by g in FIG. 1, the "position where the magnetic field strength is relatively strong" is the position where the magnetic field strength is maximum (H ｍａｘ． ) and is located at ±λ / 8=±(λ / 4) / 2, and H ｍａｘ． -λ / 8≦x ｇ ≦H ｍａｘ． +λ / 8.

[0129] For example, when the microwave frequency is 2.45 GHz, the wavelength of the microwave is λ = 122 mm, so λ / 8 = approximately 15 mm, and the position g where the magnetic field strength is relatively strong is the maximum magnetic field position (H ｍａｘ． ) and ±15 mm. In addition, when the frequency is 5.8 GHz, the wavelength λ is 52 mm, so λ / 8 is approximately 6.5 mm, and the position g where the magnetic field strength is relatively strong is the maximum magnetic field position (H ｍａｘ． ) to ±6.5 mm.

[0130] The object 20 to be processed may be placed at a position where the electric field strength is relatively strong. ｍｗ It is heated by dielectric heating or Joule heating.

[0131] In this specification, the "position where the electric field strength is relatively strong" refers to, for example, the position where the electric field strength is maximum (E ｍａｘ． ) to the electric field maximum position (E ｍａｘ． ) and the maximum magnetic field position (Hｍａｘ． ) is defined as the range up to 1 / 2 of λ / 4.

[0132] In other words, as shown by f in FIG. 1, the "position where the electric field strength is relatively strong" is the position where the electric field strength is maximum (E ｍａｘ． ) and ±λ / 8=±(λ / 4) / 2, and E ｍａｘ． -λ / 8≦x ｆ ≦E ｍａｘ． +λ / 8.

[0133] Similarly to the above, for example, when the microwave frequency is 2.45 GHz, the position f where the electric field strength is relatively strong is the position where the electric field is maximum (E ｍａｘ． ) and ±15 mm. In addition, when the frequency is 5.8 GHz, the position f where the electric field strength is relatively strong is the position where the electric field is maximum (E ｍａｘ． ) to ±6.5 mm.

[0134] When the Curie temperature of ferrite is Tc [°C], the material to be treated is preferably heated by microwave irradiation to a temperature of 0.7 x Tc [°C] or more and 1.3 x Tc [°C] or less, more preferably to a temperature of 0.8 x Tc [°C] or more and 1.2 x Tc [°C] or less, and even more preferably to a temperature of 0.9 x Tc [°C] or more and 1.1 x Tc [°C] or less.

[0135] This allows the target ferrite to be more efficiently produced in the material to be treated, and the target ferrite produced in the material to be treated to be more efficiently eluted.

[0136] For example, if the target ferrite is NiFe ２ O ４ (T Ｃ = 585°C), the material to be treated is preferably heated to 410°C or higher and 760°C or lower, more preferably 468°C or higher and 702°C or lower, and even more preferably 523°C or higher and 644°C or lower.

[0137] The frequency of the microwave is not particularly limited, but is preferably 0.9 GHz or more and 30 GHz or less, more preferably 0.9 GHz or more and 6.0 GHz or less, and even more preferably 0.9 GHz or more and 3.0 GHz or less.

[0138] By using low frequency microwaves, the magnetic heating space, in other words, the area of ​​the "position of relatively strong magnetic field strength" mentioned above, is expanded compared to the case of high frequency microwaves, making it possible to heat a larger number of objects by irradiating them with microwaves.

[0139] Microwaves for industrial, scientific, and medical use are subject to the Radio Law, which currently allows the use of microwaves at frequencies of 0.915 GHz, 2.45 GHz, 5.8 GHz, and 24.125 GHz.

[0140] As described above, when the microwave frequency is 5.8 GHz, the position g where the magnetic field strength is relatively strong is the position where the magnetic field is maximum (H ｍａｘ． ) within ±6.5 mm, but by lowering the frequency to 2.45 GHz, the position g where the magnetic field strength is relatively strong is closer to the position where the magnetic field is strongest (H ｍａｘ． ) to ±15 mm, and theoretically, it is possible to heat the material to be processed about 13 times more than in the case of 5.8 GHz.

[0141] The microwave irradiation time is not particularly limited as long as it is sufficient to magnetically heat and elute the target ferrite, but it can be, for example, from 1 second to 3600 seconds.

[0142] This allows the target ferrite to be produced more efficiently in the material to be treated, and the target ferrite produced in the material to be treated to be eluted more efficiently.

[0143] [1-4-1] External Magnetic Field Sweeping Process When irradiating the object to be treated with microwaves, a magnetic field application process may be further performed in which an external magnetic field is swept in a direction perpendicular to the magnetic field component of the microwaves.

[0144] When irradiating microwaves, an external magnetic field is applied in a direction perpendicular to the magnetic field component of the microwaves while sweeping it. If the resonance condition is met, the microwaves are more strongly absorbed by the material being treated, the temperature of the material being treated rises more quickly, and the target temperature (e.g., the Curie temperature) can be reached in a shorter time (resonance heating).

[0145] The resonance condition is generally "hν = g μ Ｂ ・H ｅｘ． " where h is Planck's constant, ν is the microwave frequency, μ Ｂ is the magnetic moment due to the electron spin, H ｅｘ． is the strength of the external magnetic field.

[0146] The resonance condition is satisfied when the magnetic field component of the microwave (H ｍｗ ) and the direction of the external magnetic field (H ｅｘ． ) direction is vertical (H ｍｗ ⊥H ｅｘ． ) and the magnetic field component of the microwave (H ｍｗ ) and the external magnetic field (H ｅｘ． ) direction is not perpendicular, for example, parallel (H ｍｗ / / H ｅｘ． ), the resonance condition is not satisfied even by sweeping the external magnetic field, and the temperature of the processed object is hardly increased by resonance heating.

[0147] FIG. 5 is a diagram showing a schematic diagram of the relationship between microwave irradiation time and temperature when an external magnetic field is further applied and the magnetic field strength is swept when microwaves are irradiated onto the object to be treated.

[0148] In addition, the external magnetic field (H ｅｘ． The magnitude of the heat flux 20 is a value measured using a gaussmeter 17, and the temperature of the object 20 to be treated is a value measured using a radiation thermometer 16.

[0149] The magnetic field component (H ｍｗ ) and the direction of the external magnetic field (H ｅｘ． ) direction is perpendicular (H ｍｗ ⊥H ｅｘ． ), the external magnetic field sweep satisfies the resonance condition (critical magnetic field: H ｅｘ． = H Ｃ ), the object to be treated 20 is heated by absorbing the microwaves, and the temperature of the object to be treated 20 increases (resonance heating).

[0150] By pre-treatment, the temperature of the material to be treated at the start of microwave irradiation (T = T ２ >T１ >RT), the temperature reached by resonance heating also increases. However, once the temperature reaches the Curie temperature (T Ｃ ), no further temperature change is observed regardless of the field sweep.

[0151] The magnetic field component of the microwave (H ｍｗ ) and the direction of the external magnetic field (H ｅｘ． ) direction is parallel (H ｍｗ / / H ｅｘ． ), the temperature of the workpiece 20 remains substantially unchanged.

[0152] [1-4-2] Steady Magnetic Field Application Process When irradiating microwaves, a magnetic field application process may be further performed in which a steady magnetic field having a constant magnetic field strength and a direction perpendicular to the magnetic field component of the microwaves is applied as an external magnetic field.

[0153] When irradiating microwaves, applying a steady-state external magnetic field in which the direction of the magnetic field component of the microwaves is perpendicular to the direction of the external magnetic field increases the microwave absorption by the material being treated, causing the temperature of the material to rise more quickly and reach the target temperature (e.g., Curie temperature Tc) in a shorter time (resonance heating).

[0154] The magnetic field strength at this time is fixed at the magnetic field strength at which the resonance condition is established by sweeping the external magnetic field strength with the direction of the magnetic field component of the microwave and the direction of the external magnetic field perpendicular to each other.

[0155] FIG. 6 is a diagram showing a schematic diagram of the relationship between microwave irradiation time and temperature when microwaves are irradiated to a processing object, and a stationary magnetic field having a constant magnetic field strength and perpendicular to the magnetic field component of the microwaves is also applied.

[0156] The magnitude of the external magnetic field is a value measured using a gaussmeter 17, and the temperature of the object 20 to be treated is a value measured using a radiation thermometer 16.

[0157] The magnetic field component (H ｍｗ ) and the direction of the external magnetic field (H ｅｘ． ) direction is perpendicular (Hｍｗ ⊥H ｅｘ． ), before microwave irradiation, an external magnetic field (H ｅｘ． ) is the magnitude of the magnetic field that satisfies the resonance condition (critical magnetic field: H ｅｘ． = H Ｃ ), and the magnetic field component of the microwave (H ｍｗ When the object 20 is irradiated with microwaves, the object 20 absorbs the microwaves and is heated. At this time, resonance occurs at the critical magnetic field, which increases the absorption of the microwaves and shortens the time required to reach the target temperature (resonance heating).

[0158] The external magnetic field is a magnetic field that does not satisfy the resonance condition (H ｅｘ． = H ２ ≠H Ｃ , H ｅｘ． = H １ ≠H Ｃ ), and the magnetic field component (H ｍｗ ), the temperature of the object 20 to be treated increases in the same way as when an external magnetic field is applied as a pretreatment, as shown in FIG.

[0159] For example, as shown in FIG. 4, when an external magnetic field is applied only in the pretreatment (H ｅｘ． = H １ , H ２ ), the direction of the magnetic field has little effect on the subsequent heating by microwave irradiation.

[0160] However, as a pretreatment, an external magnetic field (H ｅｘ． = H １ , H ２ , H Ｃ ), when microwave irradiation is continued while an external magnetic field is being applied, as shown in FIG. 6, the direction of the external magnetic field applied during microwave irradiation and the magnetic field component (H ｍｗ The effect, for example, the effect of resonance heating, varies greatly depending on the orientation of the external magnetic field. That is, when an external magnetic field is applied as a pretreatment and then microwaves are irradiated while the external magnetic field is applied, the external magnetic field applied during microwave irradiation is preferably perpendicular to the magnetic field component of the microwave.

[0161] When an external magnetic field is applied as a pretreatment and microwaves are subsequently irradiated while the external magnetic field is applied, the direction of the external magnetic field applied as a pretreatment and the direction of the external magnetic field applied when irradiating microwaves may be the same direction (parallel direction) or different directions (e.g., perpendicular direction).

[0162] As described above, according to the method for extracting ferrite of the present invention, a material to be treated is irradiated with microwaves in a steady state to generate ferrite by magnetic heating, and the ferrite can be extracted by elution. The eluted ferrite is obtained as a solid solution.

[0163] In the above-described embodiment, the case where microwaves are irradiated in a single mode has been mainly described, but the present invention is not limited to this, and for example, microwaves may be irradiated in multiple modes.

[0164] For example, even when irradiating microwaves using multi-mode, the material to be treated can be magnetically heated in the same way as in single-mode by using a "steady state" microwave in which local resonance occurs by installing a metal antenna or metal plate, or by using a metal mirror to focus the microwaves and make the standing waves resonate.

[0165] When using multi-mode, compared to single-mode, heating due to the contribution of the electric field component may cause the presence of non-magnetic impurities in the extract that have been eluted by the heating of the electric field component. In this case, since the target extract is ferrite with a Curie temperature, by additionally using a known separation method using an external magnetic field (magnetic separation), the target substance can be separated into magnetic and non-magnetic substances and extracted.

[0166] [1-5] By-products Next, by-products obtained in the ferrite extraction method of the present invention other than ferrite as the main product will be described.

[0167] By irradiating the material to be treated with microwaves, the target solid solution containing ferrite and a residual powder after extraction of the solid solution are obtained.

[0168] Ferrite in solid solution, e.g., NiFe ２ O ４ Since the solid solution reacts to a magnet, while the residual powder does not, the solid solution and the residual powder can be separated using a separation method using an external magnetic field (magnetic separation).

[0169] For example, when the nickel-containing ore to be treated contains trace amounts of rare earth elements, the ferrite NiFe extracted by the ferrite extraction method of the present invention can be obtained. ２ O ４ contains rare earth elements as a by-product.

[0170] In other words, according to the method of the present invention, ferrite NiFe is obtained from nickel-containing ore containing trace amounts of rare earth elements as a processing material. ２ O ４ In addition, RFe is produced as a by-product. ２ O ４ (R: rare earth element)-containing solid solution is obtained.

[0171] RFe obtained as a by-product ２ O ４ (R: rare earth element) is a group of materials that has attracted attention from both the magnetic and dielectric viewpoints. In particular, at low temperatures, a multiferroic state has been realized in which both ferrimagnetic (having ferromagnetic properties) and ferroelectricity coexist. This has attracted attention from an applied perspective as "green ferrite (GF)" that has polar charge ordering due to the strong correlation effect.

[0172] In addition, in conventional smelting using a rotary kiln using pyrometallurgy, coal (carbon) is added as a reducing agent and high-temperature heat treatment is carried out, and finally, magnetic separation is used to separate the product into magnetic and non-magnetic materials.

[0173] However, RFe ２ O ４ Since the Curie temperature of is below room temperature, it is usually discarded together with the non-magnetic carbon-containing residue.

[0174] Therefore, conventional techniques have not been able to recover the "rare earth elements" contained in extremely small amounts in the treated material.

[0175] In contrast, according to the method of the present invention, the rare earth elements contained in the treated material in extremely small amounts can be recovered as a solid solution together with ferrite, and can be effectively utilized. From the obtained solid solution, the target ferrite and the rare earth elements as by-products can be separated by known methods.

[0176] Furthermore, for example, when the material to be treated contains nickel and iron, iron oxide slag is obtained as a residue after ferrite extraction from the material. This residue is in the same powder form as before the extraction treatment, and its form is considered to be a porous body similar to the residue obtained after nickel removal when performing the "Method for Determining Nickel in Ore" specified in the Japanese Industrial Standard (JIS M8126-1994).

[0177] Therefore, the by-product residue has the ability to accumulate substances inside the pores, adsorb substances to its surface, or select substances or objects that can pass through based on their size. Utilizing these functions, the by-products obtained from ferrite extraction can be used in a wide range of applications, such as deodorizers and desiccants, and industrially for separating substances.

[0178] [2] Ferrite Manufacturing Method Next, a method for manufacturing ferrite of the present invention will be described. The method for manufacturing ferrite of the present invention includes the above-described method for extracting ferrite.

[0179] As a result, the method for producing ferrite of the present invention makes it possible to produce ferrite at low temperature, in a short time, and under normal pressure through simple working steps that place little strain on the environment.

[0180] Furthermore, according to the method for producing ferrite of the present invention, ferrite containing a target metal element (a metal element other than iron) as a constituent element can be obtained efficiently at low cost even from a processed material having a relatively low content of the target metal element. Therefore, ferrite containing the target metal element can be suitably obtained from a processed material having a low content of the target metal element, which has not been used in the past. Therefore, it is expected that the amount of metal resources available to humanity will increase significantly in the future.

[0181] The "method for producing ferrite" of the present invention may be composed of only the steps included in the "method for extracting ferrite" of the present invention, or may further include other steps.

[0182] As other steps, for example, the process may include a step of subjecting the treated material to a washing treatment or a pulverization treatment, an intermediate treatment step may be included between the pretreatment and the microwave irradiation, or a step of separating and purifying the target ferrite from the obtained solid solution may be included.

[0183] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these.

[0184] For example, the ferrite extraction method of the present invention is not limited to being carried out using the ferrite production apparatus described above, and may be carried out using an apparatus with a different configuration.

[0185] The ferrite extraction method of the present invention may also include steps other than the steps described above (for example, a pre-treatment step, an intermediate treatment step, a post-treatment step, etc.).

[0186] Furthermore, in the above-described embodiment, the explanation has been centered on the case where the processing object is externally heated using a heating element, but in the present invention, the processing object may also be externally heated by something other than a heating element.

[0187] Furthermore, in the above-described embodiment, the explanation has been centered on the case where an external magnetic field is applied to the processing object using an electromagnet, but in the present invention, the external magnetic field may be applied to the processing object by an external magnetic field other than an electromagnet.

[0188] The present invention will be described in detail below based on specific examples, but the present invention is not limited to these examples.

[0189] In the following description, treatments for which no particular temperature conditions are specified were performed at room temperature (23°C), atmospheric pressure (101,325 Pa), and a relative humidity of 50%. Furthermore, for various measurement conditions, values ​​for which no particular temperature conditions are specified are those measured at room temperature (23°C), atmospheric pressure (101,325 Pa), and a relative humidity of 50%.

[0190] Example 1: Nickel-containing ore (laterite ore, saprolite) produced in Indonesia was prepared as a material to be treated. This nickel-containing ore contained nickel and iron, as well as trace amounts of rare earth elements. The nickel-containing ore was powdered, and 200 mg of the powder was filled and sealed in a quartz test tube.

[0191] In the processing chamber of the ferrite manufacturing apparatus shown in Figure 1, a quartz test tube filled with nickel-containing ore was placed at a position (g) where the magnetic field strength was relatively strong, and then the movable short-circuit plate was moved to adjust the phase of the incident wave incident into the processing chamber from the microwave irradiation means and the reflected wave reflected by the movable short-circuit plate to be aligned.

[0192] The nickel-containing ore was irradiated with a steady-state microwave at a frequency of 5.8 GHz in single mode in air at atmospheric pressure.

[0193] The nickel-containing ore was heated to 700° C. by magnetic heating due to microwave irradiation. A part of the nickel-containing ore was dissolved by microwave irradiation, and a solid solution and residual powder were obtained.

[0194] (Example 2) The nickel-containing ore was magnetically heated by microwave irradiation in the same manner as in Example 1, except that the position of the quartz test tube filled with nickel-containing ore in the treatment chamber was changed to position (f) where the electric field strength was relatively strong, and a solid solution and residual powder were obtained.

[0195] Example 3 A nickel-containing ore was magnetically heated by microwave irradiation in the same manner as in Example 1, except that the heating temperature of the nickel-containing ore was 800° C., to obtain a solid solution and residual powder.

[0196] Example 4 A nickel-containing ore was magnetically heated by microwave irradiation in the same manner as in Example 2, except that the heating temperature of the nickel-containing ore was 800° C., to obtain a solid solution and residual powder.

[0197] Example 5 A nickel-containing ore was magnetically heated by microwave irradiation in the same manner as in Example 1, except that the heating temperature of the nickel-containing ore was 1000° C., to obtain a solid solution and residual powder.

[0198] Example 6 A nickel-containing ore was magnetically heated by microwave irradiation in the same manner as in Example 2, except that the heating temperature of the nickel-containing ore was 1000° C., to obtain a solid solution and residual powder.

[0199] The solid solutions obtained after heating in the above examples were subjected to measurement of X-ray diffraction patterns (XRD patterns) using a powder X-ray diffractometer (XRD). The results are shown in Figures 7 to 12, respectively.

[0200] 7 to 12, from the top to the bottom, nickel-containing laterite ore (Nickel Laterite Ore), residual powder after microwave heating (Powder), solid solution eluted by microwave heating (Melted), NiFe ２ O ４ Simulation results of SiO ２ The simulation results are also shown.

[0201] In all of Examples 1 to 6, a portion of the nickel-containing ore was eluted by microwave irradiation, and the ore was separated into a solid solution and residual powder.

[0202] As in Example 1 (see FIG. 7), Example 3 (see FIG. 9), and Example 5 (see FIG. 11), when the nickel-containing ore was placed at a position (f) where the magnetic field strength was relatively strong during microwave irradiation, NiFe ２ O ４ The peaks due to

[0203] In this way, when microwave heating is performed in a location where the magnetic field strength is strong, the nickel compounds and iron compounds, which are magnetic substances in the nickel-containing ore, are selectively heated and eluted by magnetic heating (magnetic hysteresis heating), and the target ferrite, NiFe ２ O ４ could be selectively extracted.

[0204] As in Example 2 (see FIG. 8), Example 4 (see FIG. 10), and Example 6 (see FIG. 12), even when the nickel-containing ore was placed at a position (g) where the electric field strength was relatively strong during microwave irradiation, NiFe ２ O ４ However, when the heating temperature was set to 700°C (Example 2) or 800°C (Example 4), a peak due to NiFe ２ O ４ In addition to the peaks due to SiO ２ Broad diffraction due to this has been observed.

[0205] Thus, when heated at 700°C and 800°C in a location with a strong electric field, the nickel hydrates, nickel and iron hydrates, and iron-rich silicates in this nickel-containing ore are selectively heated and dissolved, and the solid solution contains NiFe. ２ O ４ In addition, amorphous SiO ２ Since it also contains NiFe, the desired ferrite ２ O ４ It was difficult to selectively extract

[0206] On the other hand, when heated to 1000°C at a position where the electric field strength was strong (Example 6), SiO ２ Therefore, it is preferable to use a temperature of 1000° C. or higher when heating at a position where the electric field strength is strong.

[0207] With the increase in the heating temperature, the NiFe ２ O ４ The fact that this temperature range is NiFe ２ O ４ Although the melting point of NiFe is lower than that of NiFe (about 1300°C), ２ O ４ Curie temperature (T Ｃ = 585 °C), the ferrite NiFe in the nickel-containing ore ２ O ４ This is thought to be due to the magnetic phase transition from ferromagnetic to paramagnetic.

[0208] Furthermore, measurements by LA-ICP-MS (laser ablation ICP-MS) revealed that the solid solution further contained rare earth elements. The measurements by LA-ICP-MS (laser ablation ICP-MS) were performed using a Jupiter Solid neblizer (laser ablation unit) manufactured by ST Japan and an iCAP TQ (triple quadrupole inductively coupled plasma mass spectrometer, ICP-MS unit) manufactured by Thermo Fisher Scientific.

[0209] In addition, the microwave heating temperature was changed to 30°C, 200°C, 300°C, 400°C, 600°C, and 900°C, and the nickel-containing ore was magnetically heated in the same manner as in Example 1 and Example 2 described above.

[0210] FIG. 13 is a diagram showing the ratio of the solid solution to the residual powder when the microwave heating temperature is changed from 30° C. to 1000° C.

[0211] Even when the heating temperature of nickel-containing ore is 400°C to 1500°C, it separates into a solid solution and residual powder, and NiFe ２ O ４ It is possible to extract NiFe. ２ O ４ When the yield of NiFe is prioritized, the heating temperature is preferably 500°C to 1000°C. ２ O ４ When priority is given to purity, the heating temperature is preferably 500°C to 700°C.

[0212] Furthermore, when compared at the same temperature, a higher percentage of solid solution was obtained when the nickel-containing ore was placed in a position with a strong magnetic field strength than when it was placed in a position with a strong electric field strength.

[0213] Example 7: Nickel-containing ore (laterite ore, limonite) produced in Indonesia was prepared as the material to be treated. This nickel-containing ore contained nickel and iron, as well as trace amounts of rare earth elements. The nickel-containing ore was powdered, and 2 g of the powder was filled and sealed in a quartz test tube.

[0214] In the processing chamber of the ferrite manufacturing apparatus shown in Figure 1, a quartz test tube filled with nickel-containing ore was placed at a position (g) where the magnetic field strength was relatively strong, and then the movable short-circuit plate was moved to adjust the phase of the incident wave incident into the processing chamber from the microwave irradiation means and the reflected wave reflected by the movable short-circuit plate to be aligned.

[0215] The nickel-containing ore was irradiated with a steady-state microwave at a frequency of 2.45 GHz in single mode in air at atmospheric pressure.

[0216] The nickel-containing ore was heated to 750° C. by magnetic heating due to microwave irradiation. A part of the nickel-containing ore was dissolved by microwave irradiation, and a solid solution and residual powder were obtained.

[0217] Example 8 A nickel-containing ore was magnetically heated by microwave irradiation in the same manner as in Example 7, except that the heating temperature of the nickel-containing ore was 850° C., to obtain a solid solution and residual powder.

[0218] Example 9 A nickel-containing ore was magnetically heated by microwave irradiation in the same manner as in Example 7, except that the heating temperature of the nickel-containing ore was set to 1000° C., to obtain a solid solution and residual powder.

[0219] The X-ray diffraction patterns (XRD patterns) of the solid solutions obtained after heating in Examples 7 to 9 were measured using a powder X-ray diffractometer (XRD). The results are shown in FIG.

[0220] In Fig. 14, the left side shows the results of the solid solution (Melted) dissolved by microwave heating, and the right side shows the results of the remaining powder (Powder) after microwave heating. In Fig. 14, from the top to the bottom, the results of Example 9, Example 8, Example 7, and NiFe ２ O ４ Simulation results of SiO ２ The simulation results are shown.

[0221] In Examples 7 to 9, a portion of the nickel-containing ore was eluted by microwave irradiation, and the ore was separated into a solid solution and residual powder.

[0222] Furthermore, measurements by LA-ICP-MS (laser ablation ICP mass spectrometry) revealed that the solid solutions according to Examples 7 to 9 also contained rare earth elements.

[0223] Example 10: Manganese-containing ore produced in Indonesia was prepared as the material to be treated. This nickel-containing ore contained manganese and iron, as well as trace amounts of rare earth elements. The manganese-containing ore was powdered, and 200 mg of the powder was filled and sealed in a quartz test tube.

[0224] In the processing chamber of the ferrite manufacturing apparatus shown in Figure 1, a quartz test tube filled with manganese-containing ore was placed at a position (g) where the magnetic field strength was relatively strong, and then the movable short-circuit plate was moved to adjust the phase of the incident wave incident into the processing chamber from the microwave irradiation means and the reflected wave reflected by the movable short-circuit plate to be aligned.

[0225] The nickel-containing ore was irradiated with a steady-state microwave at a frequency of 5.8 GHz in single mode in air at atmospheric pressure.

[0226] The manganese-containing ore was heated to 700° C. by magnetic heating due to microwave irradiation. A portion of the manganese-containing ore was dissolved by microwave irradiation, and a solid solution and residual powder were obtained.

[0227] Example 11 A manganese-containing ore was magnetically heated by microwave irradiation in the same manner as in Example 10, except that the heating temperature of the manganese-containing ore was 800° C., to obtain a solid solution and residual powder.

[0228] Example 12 A manganese-containing ore was magnetically heated by microwave irradiation in the same manner as in Example 10, except that the heating temperature of the manganese-containing ore was 900° C., to obtain a solid solution and residual powder.

[0229] Example 13 A manganese-containing ore was magnetically heated by microwave irradiation to obtain a solid solution and residual powder in the same manner as in Example 10, except that the heating temperature of the manganese-containing ore was 1000° C. The results are shown in Figures 15 to 18, respectively.

[0230] 15 to 18, from the top to the bottom, manganese-containing ore (Manganese Ore), powder remaining after microwave heating (Powder Part), solid solution eluted by microwave heating (Melted Part), Mn ２ FeO ４ Simulation results of Mn ２ O ３ Simulation results of SiO ２ The simulation results are also shown.

[0231] In all of Examples 15 to 18, a portion of the manganese-containing ore was eluted by microwave irradiation, and it was possible to separate the ore into a solid solution and residual powder.

[0232] In particular, in Example 18, in which the heating temperature was set to 1000° C., particularly excellent results were obtained.

[0233] Furthermore, measurements by LA-ICP-MS (laser ablation ICP mass spectrometry) revealed that the solid solution further contained rare earth elements.

[0234] Furthermore, measurements by LA-ICP-MS (laser ablation ICP mass spectrometry) revealed that the solid solutions according to Examples 10 to 13 further contained rare earth elements.

[0235] <Considerations on the influence of heat treatment as pretreatment> The influence on magnetic heating by microwave irradiation when nickel-containing ore is externally heated as pretreatment prior to microwave irradiation was considered.

[0236] The nickel-containing ore was placed in the treatment chamber of the production apparatus and heated by an external heating means at a temperature of 300° C. for 2 minutes, 5 minutes, 10 minutes, and 30 minutes.

[0237] Thereafter, microwaves were applied under the same conditions as in Example 1 above at a position (g) in the treatment chamber where the magnetic field strength was relatively strong, and the temperature of the nickel-containing ore was measured.

[0238] In addition, for nickel-containing ore that had not undergone pre-treatment with heat (heating time 0 minutes), microwaves were irradiated at a position (g) in the treatment chamber where the magnetic field strength was relatively strong, and the temperature of the nickel-containing ore was measured.

[0239] FIG. 19 is a diagram showing the change over time in temperature of nickel-containing ore that has been subjected to a heat treatment as a pretreatment and then irradiated with microwaves.

[0240] When the heating time was 10 minutes, the maximum temperature increased compared to when the heating time was 0 minutes (no heat treatment). When the heat treatment was carried out for a longer period of 30 minutes, the time to reach the maximum temperature was extended.

[0241] These results show that by changing the heating time during external heating as a pretreatment, it is possible to control the temperature and time, such as increasing the maximum temperature during microwave heating or delaying the time it takes to reach the maximum temperature.

[0242] <Considerations on the influence of application of an external magnetic field as a pretreatment> The influence on magnetic heating by microwave irradiation when an external magnetic field is applied to nickel-containing ore as a pretreatment prior to microwave irradiation was considered.

[0243] The nickel-containing ore was placed in the treatment chamber of the manufacturing apparatus, and external magnetic fields of intensities of 0.125 T, 0.15 T, and 0.3 T were applied for 20 minutes each by the external magnetic field application means.

[0244] Thereafter, microwaves were applied under the same conditions as in Example 1 above at a position (g) in the treatment chamber where the magnetic field strength was relatively strong, and the temperature of the nickel-containing ore was measured.

[0245] In addition, for nickel-containing ore that was not subjected to magnetic field application (0 T) as a pretreatment, microwaves were irradiated at a position (g) in the treatment chamber where the magnetic field strength was strong, and the temperature of the nickel-containing ore was measured.

[0246] FIG. 20 is a diagram showing the change over time in temperature of nickel-containing ore that has been subjected to the application of an external magnetic field as a pretreatment and then irradiated with microwaves.

[0247] When the magnetic field strength was 0.125 T and 0.15 T, the maximum temperature increased compared to the case without pretreatment. When the magnetic field strength was 0.3 T, the time required to reach the maximum temperature was extended.

[0248] These results show that by changing the strength of the external magnetic field applied as a pretreatment, it is possible to control the temperature and time, such as increasing the maximum temperature or delaying the time it takes to reach the maximum temperature.

[0249] <Consideration of the effect of applying an external steady magnetic field during microwave irradiation> We considered the effect on magnetic heating due to microwave irradiation when an external magnetic field is applied to nickel-containing ore during microwave irradiation.

[0250] A nickel-containing ore was placed at a position (g) in the treatment chamber where the magnetic field strength was relatively strong, and microwaves were irradiated under the same conditions as in Example 1 described above. At the same time, a steady magnetic field of 0.15 T was applied by an external magnetic field application means, and the temperature of the nickel-containing ore was measured.

[0251] When the magnitude of the steady magnetic field was set to 0.40 T, the nickel-containing ore was irradiated with microwaves and the temperature was measured in the same manner as in the case where no external magnetic field was applied (0 T) during microwave irradiation.

[0252] The magnetic field component of microwaves (H ｍｗ ) and the external magnetic field (H ｅｘ． ) direction and perpendicular (H ｍｗ ⊥H ｅｘ． ) and parallel (Hｍｗ / / H ｅｘ． ) and the same measurements were carried out.

[0253] FIG. 21 is a diagram showing the change over time in temperature of a nickel-containing ore to which an external magnetic field (steady magnetic field) is applied while irradiating it with microwaves.

[0254] 21, when the magnitude of the external magnetic field was 0.15 T, the maximum temperature, the Curie temperature, was reached in a shorter time than when no external magnetic field was applied (0 T). However, when the magnitude of the external magnetic field was 0.40 T, it took a longer time to reach the maximum temperature than when no external magnetic field was applied (0 T), but the maximum temperature rose and became higher than the Curie temperature.

[0255] That is, when an external magnetic field was applied during microwave irradiation, in the low magnetic field region, the time to reach the maximum temperature (Curie temperature) was shortened as the magnetic field increased, while in the high magnetic field region, the time to reach the maximum temperature was extended, but the temperature reached was higher than the Curie temperature.

[0256] From these results, it can be said that when nickel-containing ore is microwave heated under a steady external magnetic field, the application of a high magnetic field suppresses the temperature rise and it takes time to reach the maximum temperature, so it is preferable to perform microwave heating under zero magnetic field or a steady low magnetic field.

[0257] <Considerations on the influence of external magnetic field sweep during microwave irradiation> The influence on magnetic heating due to microwave irradiation when an external magnetic field is swept to nickel-containing ore during microwave irradiation was considered.

[0258] After the temperature of the nickel-containing ore was kept constant at approximately 400°C, the nickel-containing ore was placed at a position (g) in the processing chamber of the manufacturing equipment where the magnetic field strength was relatively strong, and microwaves were irradiated under the same conditions as in Example 1 described above. The temperature of the nickel-containing ore was measured when the magnetic field was swept up to a maximum magnetic field of 0.30 T.

[0259] The magnetic field component of microwaves (H ｍｗ ) and the external magnetic field (H ｅｘ． ) direction and perpendicular (H ｍｗ ⊥H ｅｘ．) and parallel (H ｍｗ / / H ｅｘ． ) and the same measurements were carried out.

[0260] FIG. 22 is a diagram showing the change in temperature of nickel-containing ore over time when an external magnetic field is swept while microwaves are irradiated. ｅｘ． ⊥H ｍｗ In the case of (1), when the magnetic field was increased, the maximum temperature was reached rapidly at a specific magnetic field.

[0261] In particular, when the temperature of the nickel-containing ore at the start of microwave irradiation (T = 300°C > 223°C > 145°C) was increased by pretreatment, the temperature reached by resonance heating increased. Once the temperature reached the Curie temperature, no further temperature increase was observed, regardless of the magnetic field sweep.

[0262] In other words, temperature control is possible by sweeping the external magnetic field, such as shortening or extending the time required to reach the maximum temperature, or even increasing the maximum temperature.

[0263] From these results, when nickel-containing ore is microwave heated under a steady external magnetic field, the external magnetic field H ｅｘ． and microwave magnetic field H ｍｗ is vertical (H ｍｗ ⊥H ｅｘ． ) is preferable.

[0264] In addition, when considering the above-mentioned heating treatment as a pretreatment and the application of an external magnetic field during microwave irradiation, adjustment was made using a movable short-circuit plate immediately after microwave irradiation, and then readjustment was not made when the temperature of the nickel-containing ore rose. In other words, unlike the case where microwaves were irradiated to the nickel-containing ore in the above-mentioned examples, readjustment of the phase shift due to temperature changes in magnetic loss (μ') was not made. Therefore, the maximum temperature reached was the Curie temperature due to the fact that the magnetic field was not at its maximum at the insertion location of the treatment object. Microwave heating at this maximum temperature caused a portion of the nickel-containing ore to dissolve, resulting in the target NiFe ２ O ４ The solid solution and residual powder can be separated.

[0265] From the above results, it can be seen that the method of the present invention can selectively heat a nickel-containing ore containing nickel and iron by magnetic heating using microwave irradiation without using additives such as microwave absorbers or catalysts, and can produce a ferrimagnetic spinel crystal, NiFe. ２ O ４ The solid solution obtained contained RFe, which is derived from trace amounts of rare earth elements contained in the nickel-containing ore. ２ O ４ (R: rare earth element) was contained as a by-product. Furthermore, the powder obtained as a residue after extracting the solid solution was porous.

[0266] In addition, when nickel-containing ores are heated by microwaves, carbon monoxide (CO) and carbon dioxide (CO ２ ) did not emit any.

[0267] Microwave heating was carried out in the same manner as above, except that a treatment material containing Mn, Co, Mg or Cu and iron was used instead of nickel-containing ore, and it was confirmed that the corresponding ferrite could be efficiently extracted.

[0268] The ferrite extraction method of the present invention involves irradiating a material to be treated with microwaves in a steady state to generate ferrite by magnetic heating, and then extracting the ferrite by elution. Therefore, it is possible to provide a ferrite extraction method that can extract ferrite at low temperature, in a short time, and under normal pressure using simple work steps with little environmental impact.

[0269] The method for producing ferrite of the present invention includes the above-mentioned ferrite extraction method, and therefore, it is possible to provide a method for producing ferrite at low temperature, in a short time, and under normal pressure through simple work steps with little environmental impact.

[0270] The present invention also provides a ferrite manufacturing apparatus that includes a processing chamber in which an object to be processed is placed, microwave irradiation means for irradiating the object to be processed placed in the processing chamber with steady-state microwaves to magnetically heat the object to be processed, and external magnetic field application means for applying an external magnetic field to the object to be processed. Therefore, it is possible to provide a ferrite manufacturing apparatus with a simple configuration that is environmentally friendly, capable of manufacturing ferrite at low temperature, in a short time, and under normal pressure.

[0271] Therefore, the ferrite extraction method, ferrite manufacturing method, and ferrite manufacturing apparatus of the present invention have industrial applicability.

[0272] REFERENCE SIGNS LIST 1: Ferrite manufacturing apparatus 10: Processing chamber 11: Microwave irradiation means 12: Iris 13: Movable short-circuit plate 14: External magnetic field application means 15: External heating means 16: Radiation thermometer 17: Gauss meter 18: Control unit 20: Processed object E ｍｗ : microwave electric field component H ｍｗ : Microwave magnetic field component H ｅｘ． : External magnetic field E ｍａｘ． : Maximum electric field position H ｍａｘ． : Maximum magnetic field position f: Position with relatively strong electric field strength g: Position with relatively strong magnetic field strength

Claims

1. A method for extracting ferrite, in which a material to be treated is irradiated with steady-state microwaves, ferrite is generated by magnetic heating, and the ferrite is then eluted and extracted.

2. The method for extracting ferrite according to claim 1, wherein the material to be treated is nickel-containing ore.

3. The method for extracting ferrite according to claim 1, wherein the material to be treated is placed in a position where the magnetic field strength is relatively strong.

4. A method for extracting ferrite as described in claim 1, in which the material to be treated is heated to a temperature of 0.7 x Tc [°C] or more and 1.3 x Tc [°C] or less by irradiating the microwaves, where Tc [°C] is the Curie temperature of the ferrite.

5. The method for extracting ferrite according to claim 1, wherein the microwave frequency is 0.9 GHz or more and 30 GHz or less.

6. The method for extracting ferrite according to claim 1, further comprising the steps of: performing a heat treatment and / or a magnetic field application treatment in which an external magnetic field is applied as a pretreatment to the material to be treated before the microwave irradiation.

7. A method for extracting ferrite as described in claim 6, wherein the pretreatment heats the treated material to a temperature less than 0.7 x Tc [°C], where Tc [°C] is the Curie temperature of the ferrite.

8. The method for extracting ferrite according to claim 6, further comprising the step of performing the magnetic field application process of sweeping the external magnetic field in a direction perpendicular to the magnetic field component of the microwaves when irradiating the microwaves.

9. A method for extracting ferrite as described in claim 6, further comprising the step of applying a magnetic field as the external magnetic field, the magnetic field having a constant magnetic field strength and a direction perpendicular to the magnetic field component of the microwaves, when irradiating the microwaves.

10. A method for producing ferrite, comprising the method for extracting ferrite according to any one of claims 1 to 9.

11. A ferrite manufacturing apparatus comprising: a processing chamber in which an object to be treated is placed; a microwave irradiation means for irradiating the object to be treated placed in the processing chamber with steady-state microwaves to magnetically heat the object to be treated; and an external magnetic field application means for applying an external magnetic field to the object to be treated.

12. The apparatus for producing ferrite according to claim 11, further comprising an external heating means for heating the object to be treated in addition to the magnetic heating.

13. A ferrite manufacturing apparatus as described in claim 11 or 12, further comprising a metallic movable short-circuiting plate disposed within the processing chamber, and the phase of the incident wave incident into the processing chamber from the microwave irradiation means and the phase of the reflected wave reflected by the movable short-circuiting plate are adjusted by moving the movable short-circuiting plate.

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