JP5445230B2 - Method for reducing iron oxide-containing substance by microwave heating, method for producing raw material for producing sinter, and method for producing blast furnace raw material - Google Patents

Description

  The present invention relates to a method for heating and reducing an iron oxide-containing substance by irradiating a microwave having a frequency range of 20 to 30 GHz, and using this method, The present invention relates to a method for producing a blast furnace raw material.

  In recent years, attempts have been made in various fields to apply a heating phenomenon (that is, microwave oven technology) by irradiating a microwave, which is a kind of electromagnetic wave, to various industrial processes. Compared with the conventional heating process, microwave heating can (1) rapidly heat the substance itself that absorbs the microwave from the inside (rapid heating, internal heating), (2) microwave It is possible to select and heat only the substance to be absorbed (selective heating). (3) Non-thermal effects that cannot be produced by heating with a normal electric furnace or the like (effects other than temperature rise caused by microwaves) In addition to the drying field that has been studied in the past, in recent years, by applying microwave heating to the reduction reactions of various metal oxides including iron ore. Consideration has been actively made to establish a reduction process that is more efficient than before.

  For example, in Patent Document 1, a powdered iron oxide raw material is mixed with a charcoal and carbonate as a reducing agent, and irradiated with microwaves to reduce iron oxide to produce iron powder. A method has been proposed.

  Further, Patent Document 2 proposes a method for producing a metal by irradiating a container filled with a metal-containing material and a reducing agent with microwaves and additionally applying energy such as an electric arc.

JP 06-279,824 Special table 2004-526,864

Akinori Shigemi, “Seikan Handbook” Jinshokan, December 10, 1979, p. 73

  By the way, when heating by a microwave is carried out, naturally the to-be-heated substance (substance in which the substance itself is heated from the inside) must be a substance that absorbs microwaves. And the following is defined as Formula (1) which shows how much an object can be heated by irradiating a microwave.

Ｐ：物質に吸収されるマイクロ波エネルギー[W/m³]
Ｅ：電場[V/m]
Ｈ：磁場[A/m]
σ：導電率[S/m]
ｆ：周波数[Hz]
ε₀：真空の誘電率[F/m]
ε^"：誘電損失
μ₀：真空の透磁率[H/m]
μ^"：磁気損失

P: Microwave energy absorbed by the substance [W / m ³ ]
E: Electric field [V / m]
H: Magnetic field [A / m]
σ: Conductivity [S / m]
f: Frequency [Hz]
ε ₀ : Vacuum dielectric constant [F / m]
ε ^" : Dielectric loss μ ₀ : Vacuum permeability [H / m]
μ ^" : Magnetic loss

Based on this formula (1), a substance having a large physical constant such as conductivity, dielectric loss, magnetic loss, etc. in a certain microwave electromagnetic field is a substance that absorbs microwave well and is easily heated by microwave. It is defined as For example, there are forms of iron oxide such as hematite (ferric oxide / Fe ₂ O ₃ ), magnetite (triiron tetroxide / Fe ₃ O ₄ ), and wustite (ferrous oxide / FeO). Assuming the use of microwaves with a frequency (2.45 GHz) generally used in Japan, it is difficult to heat by microwave alone because hematite has poor microwave absorption Are known.

Therefore, in the case of iron ore, which is the main raw material in the iron and steel industry, heating with microwaves can be carried out without any problem if it is a magnetite mainly composed of magnetite, but the reserves are large and the current mainstream. For iron ore (hematite, limonite) mainly composed of hematite or trivalent iron-based iron hydroxide (goethite / Fe ₂ O ₃ · 3H ₂ O) similar to hematite Alone, heating by microwaves cannot be performed effectively. In addition, by-products generated at steelworks (blast furnace dust, converter dust, neutralized sludge, etc.) are often reused as raw materials for iron making, but these main components are also hematite or goethite. In many cases, it is not possible to effectively heat these by-products alone by microwaves.

  Therefore, in Patent Document 1 and Patent Document 2, it is stated that when hematite is used as a raw material, it is necessary to separately mix a substance having high microwave absorptivity (such as carbon or magnetite).

  Here, in order to reduce iron oxide, it is natural that in any case it is necessary to add carbon as a reducing agent. However, according to Patent Document 1, hematite is favorably microwave-heated. Describes that it is necessary to add more than twice as much extra carbon to the equivalent amount required for the reduction of iron oxide, and there was a problem from the viewpoint of wasting costs related to the reducing agent. In addition, since excess carbon that does not contribute to the reduction reaction is heated to a temperature equal to or higher than that of iron oxide, it is necessary to increase the microwave output accordingly, and as a result, it is necessary to generate microwaves. There was also a problem of consuming large amounts of power.

  In addition, it is known that there are substances that improve microwave absorption with increasing temperature, even if the substance has poor microwave absorption at room temperature. Some have been reported to be highly temperature-dependent. Therefore, Patent Document 2 also proposes a method of heating by a microwave and reducing a metal after preheating the material to be heated to a critical temperature at which microwave absorption is improved by a method such as electric furnace heating. . However, in this method, the reduction treatment cannot be carried out with a single reactor by microwave heating necessary for metal reduction, and a preheating reactor that does not contribute to any reduction reaction is required separately.

  By the way, the present inventors reduced a substance containing hematite or goethite to a substance mainly composed of magnetite with a reducing gas, and then mixed the reducing substance with carbon (reducing agent). A method for obtaining metallic iron by heating by irradiation with microwaves has been proposed (filed in Japanese Patent Application No. 2009-073,169). Also in this method, since pre-reduction using a reducing gas is necessary as a pretreatment for microwave heating, a reactor for performing pre-reduction using a reducing gas is required separately from the heating equipment using microwaves. .

  Therefore, the present inventors have further considered the following idea regarding a method for more efficiently heat-treating an iron oxide-containing substance mainly composed of hematite or goethite by microwave irradiation and reducing the iron oxide-containing substance. The investigation was conducted below.

  Generally, a microwave is defined as an electromagnetic wave having a frequency in the range of about 300 MHz to 300 GHz. In practice, however, the frequency of microwaves currently used for microwave heating applications is quite limited. Regarding frequencies other than 2.45 GHz that are widely used in microwave ovens and output from inexpensive oscillators (magnetrons) The reality is that is almost never used. There is an example in which the frequency of 0.915 GHz on the short wavelength side is used very slightly, but the region on the high frequency side (short wavelength side as the wavelength) than 2.45 GHz (called millimeter wave, submillimeter wave) In many cases, oscillators that output such high-frequency microwaves (klystrons, gyrotrons, etc.) are not widely used, and the fact that they are expensive has helped them not be studied. It is.

  Electromagnetic waves are said to interact with substances in various forms in proportion to their energy levels. Since the energy of electromagnetic waves increases as the wavelength decreases (as the frequency increases), so-called high-energy electromagnetic waves such as γ-rays and X-rays can interact with nuclei and electrons inside the atom. Ultraviolet rays, visible light, and near infrared rays having low energy can mainly affect the transition of electrons in the solid, and infrared rays, which are electromagnetic waves having lower energy, can affect the vibration and rotation of molecules. On the other hand, microwaves having lower energy than these electromagnetic waves are said to be at a level that mainly interacts with electric dipoles in the substance and induces orientational polarization. However, the so-called non-thermal effect associated with microwave heating is also considered to be a phenomenon caused by the interaction between these microwaves and substances.

  Therefore, the present inventors have promoted interaction with a substance by using microwaves on the shorter wavelength side (high frequency side) than microwaves of 2.45 GHz even for electromagnetic waves in the same microwave region. And reached the idea that a non-thermal effect can be expected to be further amplified, and as already mentioned, at room temperature of about 20-30 ° C., such as hematite or goethite It is widely known that when iron oxide based on trivalent iron is irradiated with microwaves of 2.45 GHz, microwaves are hardly absorbed and can be heated with only a slight temperature rise. However, as shown in the equation (1) above, the physical constants related to microwave heating (dielectric loss, magnetic loss, etc.) are functions depending on the frequency, and microwave heating (microwave absorption) Is further promoted at higher frequencies and in a strong electromagnetic field atmosphere, so by shifting the microwave frequency to a higher frequency side than the conventional 2.45 GHz, hematite or It came to the idea that materials such as goethite could easily be heated and in addition non-thermal effects could be amplified.

  As a result of many examinations based on the above-mentioned idea, the present inventors, as a result of the iron oxide-containing substance mainly composed of hematite and goethite, which does not increase in temperature at 2.45 GHz, which is currently widely used, When microwaves having a frequency of about 10 times were irradiated, it was surprisingly found that it was possible to heat to 1000 ° C. or higher in a short time, and the present invention was made.

  Therefore, an object of the present invention is to provide a method for reducing an iron oxide-containing substance by heat-treating an iron oxide-containing substance mainly composed of hematite such as hematite or goethite by microwave irradiation. It is to be.

  In addition, the present invention is an iron oxide-containing substance mainly composed of hematite or goethite such as hematite, even in a state where there is almost no reducing agent. It is also an object to provide a method for reducing contained substances.

  Still another object of the present invention is to provide a method for producing a sintered ore raw material or a blast furnace raw material in a steel production process by the method for reducing an iron oxide-containing substance by microwave irradiation described on the left.

In order to achieve the above object, the gist of the present invention is as follows.
(1) heating the iron oxide-containing substance by irradiating the iron oxide-containing substance containing at least one of hematite and goethite with a microwave having a frequency in a range of 20 to 30 GHz; A method for reducing an iron oxide-containing material by microwave heating, comprising reducing iron oxide containing at least one of the hematite and goethite contained in the iron oxide-containing material.

  (2) The method for reducing an iron oxide-containing substance by microwave according to (1), wherein the microwave irradiation to the iron oxide-containing substance is performed in a state of coexisting with a reducing agent.

  (3) The microwave according to (2), wherein the reducing agent is a carbon-containing substance, and the mixture obtained by adding the reducing agent to the iron oxide-containing substance is irradiated with microwaves. A method for reducing iron oxide-containing substances by heating.

  (4) The reducing agent according to (2) or (3), wherein the reducing agent is a reducing gas, and the microwave irradiation to the iron oxide-containing substance is performed in the reducing gas. Reduction method of iron oxide-containing substances by waves.

  (5) The iron oxide-containing substance is reduced by microwave heating according to any one of (1) to (4), and the reduced iron oxide-containing substance is used in a sinter ore production process. A method for producing a raw material for producing sintered ore, characterized in that the raw material is used as a raw material.

  (6) The iron oxide-containing substance is reduced by microwave heating according to any one of (1) to (4), and the reduced iron oxide-containing substance is used as a raw material in a blast furnace process. A method of producing a blast furnace raw material characterized by the above.

  Even an iron oxide-containing substance mainly composed of hematite or goethite can be efficiently heat-treated by microwave heating to reduce the iron oxide-containing substance. In addition, even iron oxide-containing substances mainly composed of hematite and goethite can be produced by raw material for sinter ore production in the steel production process or blast furnace raw material in the blast furnace process by reduction by microwave heating. It becomes.

FIG. 1 is an explanatory diagram showing an example of a microwave heat treatment apparatus for carrying out the method of the present invention.

FIG. 2 is a graph comparing the microwave heating characteristics of the present invention and the prior art. FIG. 3 is a graph comparing the microwave heating characteristics of the present invention and the prior art under different conditions.

FIG. 4 is a graph comparing the microwave heating characteristics of the present invention and the prior art under still another condition. FIG. 5 is a graph showing the “graph showing the relationship between temperature and iron oxide dissociation” described in Non-Patent Document 1.

FIG. 6 is an explanatory view showing the microwave heat treatment apparatus used in the example of the present invention. FIG. 7 is an explanatory view showing the microwave heat treatment apparatus used in the comparative example.

Hereinafter, the present invention will be described in detail.
FIG. 1 shows an example of a microwave heat treatment apparatus according to the present invention. Here, the present apparatus can irradiate microwaves of 24 GHz out of microwaves of 20 to 30 GHz according to the present invention, and can also irradiate microwaves of 2.45 GHz for comparison. That is, it is possible to irradiate the to-be-heated substance 2 installed in the applicator (reactor) 1 with microwaves of two different frequencies. As the types of microwaves, two frequencies of 2.45 GHz and 24 GHz can be selected (an error of about ± 500 MHz can occur due to the characteristics of the oscillator. The same applies hereinafter), and each microwave is magnetron 3, gyro. It is generated using an individual dedicated oscillator called TRON 4, and the microwave is not focused on a specific position, but is randomly and unsteadily flying around the applicator 1 (multi-mode), and the heated material 2 as a whole Can be heated as uniformly as possible. The atmosphere in the applicator 1 can be arbitrarily adjusted by adding an atmospheric gas 5 from the outside. Further, the temperature of the heated material 2 is protected by a metal tube sheath having an outer diameter of 8 mm. The thermocouple 7 is inserted into a powder sample, and the average temperature inside the powder can be measured.

Using this device, various samples were irradiated with microwaves and tested for heating and reduction. The results of these test examples are shown below.
In the following test examples, the iron (Fe) reduction rate is the actual oxygen content that is removed when hematite is reduced to metallic iron (M-Fe). It is an index indicating whether it has been removed. When all of the iron oxide-containing materials after microwave irradiation are hematite, the reduction rate is 0%, when all are magnetite, the reduction rate is 11.1%, and all are wustite (FeO ), The reduction rate = 33.3%, and when all are metallic iron, the reduction rate = 100%. In other words, a reduction rate of 11.1% means that all hematite has been reduced to magnetite, and a reduction rate of 5% means that hematite and magnetite are mixed (assuming no reduction after wustite occurs). It is in the state.

Further, in the following test examples, the quantitative analysis of the iron form (M-Fe, FeO, Fe ₂ O ₃ ) was carried out by an analytical method such as a fluorescent X-ray analysis method or a volumetric method (JIS M8213). Since these analytical methods cannot quantify the content of magnetite (Fe ₃ O ₄ = FeO · Fe ₂ O ₃ ), it is impossible to accurately grasp the content of each of wustite, magnetite, and hematite. . Therefore, the form of iron oxide (wustite, magnetite, hematite) present in the sample was estimated from the Fe reduction rate calculated from the results of quantitative analysis and the results of qualitative analysis of iron form by X-ray diffraction analysis.

[Test Example 1]
First, a hematite reagent (special grade / purity 99.0% or more, 100 g) is used as the substance 2 to be heated, and the atmosphere in the applicator 1 is argon (the partial pressure of oxygen contained as an impurity in the supplied argon gas is 10 ^−4. The material 2 to be heated was irradiated with a 2.45 GHz microwave generated by the magnetron 3 or a 24 GHz microwave generated by the gyrotron 4 at an output of 400 W, respectively. FIG. 2 shows the temperature change of the hematite reagent at that time.

When irradiated with a 2.45 GHz microwave (microwave irradiation time of 255 minutes), the hematite reagent showed only a slight increase in temperature (maximum temperature of 80 ° C.), as known to date. When the frequency of 24 GHz was irradiated (microwave irradiation time 70 minutes), it was found that even the hematite reagent alone could be heated to a temperature of 1000 ° C. or higher (maximum temperature 1200 ° C.) very rapidly.
Table 1 shows the composition of hematite and the reduction rate of Fe after heating in the above.

  As is clear from the results shown in Table 1, the hematite reagent when irradiated with the 2.45 GHz microwave was only heated up to about 80 ° C., and naturally, hematite was hardly reduced. It was found that when heating with microwaves at 24 GHz, the reduction of hematite progressed significantly.

[Test Example 2]
Next, lobe river ore (particle size: 0.25 mm or less, 150 g) having the composition shown in Table 2 is used as the material to be heated 2, and the atmosphere in the applicator 1 is argon (oxygen contained as an impurity in the supplied argon gas). a partial pressure 10 ^-4 MPa) for, in the same manner as in test example 1 using the previous hematite reagent, a microwave 2.45GHz microwave or 24GHz was irradiated at an output of 400W, respectively. FIG. 3 shows the temperature change of the lobe river ore at that time.

In the case of Test Example 2 using lobliber ore, since components other than hematite (microwave absorption is different from hematite) are contained, it takes a certain amount of time, but when 2.45 GHz microwave is irradiated ( Even with a microwave irradiation time of 240 minutes, it was possible to heat to a high temperature of 1000 ° C. or higher (maximum temperature 1320 ° C.). However, when irradiated with 24 GHz microwaves (microwave irradiation time 70 minutes), heating to a temperature of 1000 ° C. or higher (maximum temperature 1230 ° C.) is much faster than when using a frequency of 2.45 GHz. It was possible to do.
Table 3 shows the composition of the lobe river ore and the Fe reduction rate after heating in the above.

  As is apparent from the results shown in Table 3, the lobe river ore when heated with microwaves at 24 GHz has a higher Fe reduction rate than when heated with microwaves at 2.45 GHz, and wustite (FeO). It turned out that the reduction to the level was progressing. The crystal water in the lobe river ore was also removed.

[Test Example 3]
Next, neutralized sludge having the composition shown in Table 4 is used as the material to be heated 2 (sample of ironworks by-product and dried by a dryer: average particle size 30 μm, 50 g), and the atmosphere in the applicator 1 is argon. (The partial pressure of oxygen contained as an impurity in the supplied argon gas is 10 ⁻⁴ MPa) As in Test Example 1 using the previous hematite reagent, a 2.45 GHz microwave or a 24 GHz microwave was applied. Irradiation was performed at an output of 400 W each. In FIG. 4, the temperature change of the neutralization sludge in that case is shown.

In the case of Test Example 3 using neutralized sludge, since a large amount of components other than hematite (differing in microwave absorption from hematite) is contained, when 2.45 GHz microwave is irradiated (microwave irradiation time) 240 minutes), even when 24 GHz microwaves are irradiated (microwave irradiation time 60 minutes), a temperature of 1000 ° C or higher (2.45 GHz: maximum temperature 1360 ° C, 24 GHz: 1200 ° C.).
Table 5 shows the composition of the neutralized sludge and the reduction rate of Fe after heating in the above.

  As is clear from the results shown in Table 5, neutralized sludge heated with 2.45 GHz microwaves was only reduced to the magnetite level (estimated from Fe reduction rate and X-ray diffraction analysis results). ), In the case of neutralized sludge heated by microwaves at 24 GHz, the Fe reduction rate was significantly large, and it was found that the reduction to the wustite level, and partly to the metallic Fe level (Fe) Estimated from reduction rate and X-ray diffraction analysis results). Also, the removal rate of chlorine contained in the neutralized sludge was larger when heated by microwaves at 24 GHz.

In Test Examples 1 to 3, when the hematite reagent and the lobe river ore are heated by microwave, the reducing agent (carbon) is not present at all, and the atmospheric gas is argon and contains no reducing gas component. It has not been. Therefore, the reduction phenomenon caused by microwave heating is presumed to originate solely from the thermal decomposition (oxygen dissociation) reaction accompanying heating of iron oxide to a high temperature. The neutralized sludge originally contains a very small amount of carbon, but the actual sample after 24 GHz microwave heating has the maximum reduction rate that can theoretically occur using that carbon as a reducing agent. Since the reduction reaction proceeds until exceeding (assuming that the reduction from C + 2O to CO ₂ occurs), the thermal decomposition reaction of iron oxide is the main component as in the case of lobe river ore. Presumed.

FIG. 5 introduces a “graph showing the relationship between temperature and iron oxide dissociation” described in Non-Patent Document 1. From FIG. 5, the oxygen partial pressure (10 ⁻⁴ MPa≈10 ⁻³ atm, logPo ₂ = −3 [atm] in argon gas used in Test Examples 1 to 3 this time; coexisting substances such as carbon and oxygen It is possible that the oxygen partial pressure in the applicator is slightly lower than this due to the equilibrium of the temperature.) Nearly, the temperature reached in the microwave heating at 24 GHz (about 1200 to 1230 ° C) Then, it can be seen that thermal decomposition (reduction) from hematite to magnetite can occur, but thermal decomposition (reduction) from magnetite to wustite cannot occur.

  With respect to the lobe river ore in Test Example 2 and the neutralized sludge in Test Example 3, when microwaves of 24 GHz rather than 2.45 GHz were used (and the maximum temperature was when heated by microwaves of 24 GHz) Although it is lower), the reduction of iron oxide (pyrolysis reaction) is greatly promoted, and the reason why the reduction is proceeding beyond the theoretically possible level is unclear. Factor (1) The strong electromagnetic field of microwaves at 24 GHz promoted the oxygen dissociation phenomenon by some mechanism. Factor (2) Internal heating, which is a feature of microwave heating, was further amplified by microwaves at 24 GHz. The internal temperature of the ore and neutralized sludge particles was significantly higher than the temperature measured by the thermocouple (only the average temperature of each particle surface was measured) It can be considered. However, with respect to the hematite reagent in the case of Test Example 1, even when heated with a microwave of 24 GHz, since the reduction hardly progresses, Fe contained in the lobe river powder ore and neutralized sludge Factor (2) is large as a reason, including the effects of substances other than (including heating to a higher temperature than Fe due to microwave heating characteristics, and the adjacent Fe is also heated locally to a similar level) It is estimated that.

  Thus, when no reducing agent is added from the outside, reduction of iron oxide proceeds in an atmosphere of the applicator 1 that is an inert gas atmosphere, particularly an atmosphere in which the partial pressure of oxygen contained as an impurity is as low as possible. To do. However, the oxygen partial pressure in the atmosphere gas is not particularly limited as long as the Fe reduction rate may be lower than that in the case of performing the reduction in an inert gas atmosphere, and the normal air atmosphere Below, heating by microwaves of 24 GHz may be performed.

  In order to further increase the Fe reduction rate after microwave heating of these iron oxide-containing substances (in the above-described Test Examples 1 to 3, hematite reagent, lobe river ore, neutralized sludge, etc.), the iron oxide-containing substance is a reducing agent. It is effective to irradiate the iron oxide-containing substance with the microwave in a state where it coexists with the iron oxide. In particular, when the iron oxide-containing substance does not contain a reducing substance such as carbon, it is more effective to add some reducing agent from the outside. In this case, as the reducing agent, solid reducing agent (coal, coke, char, carbon black, graphite, woody biomass, sewage sludge, waste plastic, waste tire, etc.), liquid reducing agent (coal tar, methanol, Ethanol etc.) or gaseous reducing agent (hydrogen, carbon monoxide, methane, coke oven gas, blast furnace gas, coal gasification gas, methane reformed gas, coke oven gas reformed gas, blast furnace gas reformed gas, etc. ), Etc., and anything may be used. When solid and liquid reducing agents are used, they may be mixed in advance with an iron oxide-containing substance, and when a gaseous reducing agent is used, the atmospheric gas in the applicator may be mixed with these gaseous substances. The reducing agent atmosphere may be used.

  In general, in the process of producing reduced iron from iron oxides such as iron ore, when using an inexpensive solid reducing agent, or when the reduction rate is high, the reduction rate can be reduced at a lower temperature. In many cases, an agent is used, but a liquid reducing agent may be used as long as it can be uniformly mixed with the iron oxide-containing substance. Further, when using a solid or liquid reducing agent, the atmospheric gas in the applicator 1 is changed to an inert gas (nitrogen, argon, etc.) atmosphere not containing oxygen so that the reducing agent does not burn and disappear. There is a need to. Of course, the inert gas atmosphere may contain some (less than 3vol%) oxygen, but the oxygen burns the reducing agent and disappears. It is necessary to add extra reducing agent. Furthermore, there is no problem even if some combinations of solid, liquid and gaseous reducing agents are used.

  The frequency of the microwave generated from the gyrotron 4 is not limited to 24 GHz, and is 20 GHz to 30 GHz, preferably 24 GHz to 28 GHz, having an energy density (electromagnetic field strength) about 10 times that of 2.45 GHz. Any frequency within the following range may be used. Although it is possible to use microwaves in a frequency region larger than 30 GHz, as shown in the following formula (2), the microwave penetration depth (penetration depth) is conversely the microwave on the high frequency side. When microwaves with a frequency higher than 30 GHz are used, there is a possibility that the whole heated material cannot be heated uniformly, which is not preferable. In addition, microwave transmission devices with frequencies of 24 GHz and 28 GHz are preferable because they are relatively easy to obtain and the cost is relatively low.

δ：浸透深さ[m]
ｆ：周波数[Hz]
μ：透磁率[H/m]
σ：導電率[S/m]

δ: penetration depth [m]
f: Frequency [Hz]
μ: Permeability [H / m]
σ: Conductivity [S / m]

  In the present invention, the iron oxide-containing substance is not limited to the above-described hematite reagent, robe river ore, and neutralized sludge. Any material may be used as long as it contains iron oxide containing hematite or goethite (oil-containing sludge, blast furnace dust, converter dust, etc.). In addition, after these iron oxide-containing substances have been treated once in other pretreatment equipment (drying equipment, preheating equipment, prereduction equipment, etc.), they are subjected to microwave heat treatment as the iron oxide-containing substance of the present invention. It doesn't matter.

  The processed product obtained by subjecting the iron oxide-containing substance to microwave heat treatment by the method of the present invention can be used as a raw material for ironworks. Regarding the treated product of the present invention having a high M-Fe content ratio and a high Fe reduction rate, it is desirable to use it as a blast furnace raw material after being formed into briquettes. Moreover, it is also possible to use it as a blast furnace raw material by blowing it from a tuyere of a blast furnace without forming it into a briquette. By using these reduced samples as raw materials, the amount of reducing agent (coke, pulverized coal, etc.) used in the blast furnace can be reduced. In addition, it is desirable to use the sample as a raw material for the sintering machine in a powder state with respect to a sample that hardly contains M-Fe and that has been reduced only to the extent of wustite or magnetite. By using the processed product of the present invention after reduction as a raw material, it is possible to reduce the amount of fuel (powder coke, anthracite, etc.) used in the sintering machine.

Example 1
The present invention example according to Example 1 was carried out using the same microwave heat treatment apparatus as shown in FIG. 1 shown in FIG.
In the applicator 1, a hematite reagent (special grade: purity 99.0% or more, 100 g) is disposed as the material to be heated 2, and hydrogen is circulated in the applicator 1 as an atmospheric gas 5, and a microwave of 24 GHz from the gyrotron 4 is used. Was oscillated and 24GHz microwave irradiation (output 400W, multimode) was applied to the material 2 to be heated. The temperature was rapidly raised to 900 ° C in 20 minutes. went. In addition, the thermocouple 7 was used for temperature measurement, and it measured in the state which the powder of the hematite reagent and the thermocouple temperature-measurement part contacted sufficiently.

  Table 6 shows the composition of the hematite reagent and the Fe reduction rate after the microwave heat treatment. As apparent from the results shown in Table 6, in Example 1, most of the hematite in the hematite reagent could be efficiently reduced to metallic iron.

(Example 2)
The present invention example according to Example 2 was carried out using the same microwave heat treatment apparatus as shown in FIG. 1 shown in FIG.
In the applicator 1, lobe river powder ore (particle size 1 to 3 mm, 150 g) having the composition shown in Table 2 is arranged as the material to be heated 2, and nitrogen (partial pressure of oxygen contained as an impurity) is used as the atmosphere gas 5. 10 ^-4 MPa) was circulated, and a microwave of 24 GHz was oscillated from the gyrotron 4 to irradiate the material 2 to be heated with a microwave of 24 GHz (output 400 W, multimode). Since the temperature was rapidly raised to 0 ° C., heat treatment was performed for 30 minutes at that temperature. In addition, the thermocouple 7 was used for temperature measurement, and it measured in the state which the powder of the lobe river powder ore and the thermocouple temperature-measurement part contacted sufficiently.

  Table 7 shows the composition of the lobe river powder ore after the microwave heat treatment and the Fe reduction rate. As is apparent from the results shown in Table 7, in Example 2, hematite (or goethite) in lobe river powder ore is reduced to a mixed state of magnetite and wustite (Fe reduction rate and X-ray diffraction analysis results). It was possible to estimate). Moreover, by using the powdered ore after the microwave heat treatment as a raw material for a sintering machine at an ironworks, it was possible to reduce fuel (powder coke, anthracite, etc.) used in the sintering machine.

(Example 3)
The present invention example according to Example 3 was carried out using the same microwave heat treatment apparatus as shown in FIG. 1 shown in FIG.
In the applicator 1, lobe river powder ore (particle size 1 to 3 mm, 150 g) having the composition shown in Table 2 is disposed as the heated material 2, and hydrogen is circulated as the atmosphere gas 5, and the gyrotron 4 has a frequency of 24 GHz. Microwave was oscillated and 24GHz microwave irradiation (output 400W, multimode) was applied to the material 2 to be heated. The temperature rapidly increased to 900 ° C in 20 minutes. Processed. In addition, the thermocouple 7 was used for temperature measurement, and it measured in the state which the powder of the lobe river powder ore and the thermocouple temperature-measurement part contacted sufficiently.

  Table 8 shows the composition of the lobe river powder ore after the microwave heat treatment and the Fe reduction rate. As is clear from the results shown in Table 8, in Example 3, hematite (or goethite) in the lobe river powder ore could be rapidly reduced to almost the state of metallic iron. In addition, the powdered ore after the microwave heat treatment is formed into briquettes and then used as a blast furnace raw material in an ironworks, thereby reducing the fuel or reducing agent (coke, pulverized coal, etc.) used in the blast furnace. did it.

Example 4
The present invention example according to Example 4 was carried out using the same microwave heat treatment apparatus as shown in FIG. 1 shown in FIG.
In the applicator 1, the lobe river powder ore having the composition shown in Table 2 (particle size 1 to 3 mm, 150 g) and the powdered coke having the composition shown in Table 9 (particle size 3 mm or less, average particle size 0.7 mm) , 38 g) (lobe river fine ore 100: fine coke 25 as mass ratio) and nitrogen (the partial pressure of oxygen contained as impurities is 10 ⁻⁴ MPa) as an atmospheric gas 5 circulates, When the microwave of 24 GHz was oscillated from the gyrotron 4 and the microwave irradiation of 24 GHz was applied to the heated material 2 (output 400 W, multimode), the temperature rapidly increased to 1300 ° C. in 25 minutes. The heat treatment was performed for 30 minutes while maintaining the temperature. In addition, the thermocouple 7 was used for temperature measurement, and it measured in the state which the powder and the thermocouple temperature-measurement part which consisted of the mixture of lobe river powder ore and powder coke fully contacted.

  In Table 10, the composition and Fe reduction | restoration rate are shown about the mixture of the lobe river powder ore and the powder coke after a microwave heat processing. As is clear from the results shown in Table 10, in Example 4, it was possible to quickly reduce most of the hematite (or goethite) in the lobe river powder ore to the state of metallic iron. The powdered ore after heating was formed into briquettes and then used as a blast furnace raw material in an ironworks, thereby reducing the fuel or reducing agent (coke, pulverized coal, etc.) used in the blast furnace.

(Example 5)
The present invention example according to Example 5 was carried out using the same microwave heat treatment apparatus as shown in FIG. 1 shown in FIG.
In the applicator 1, neutralized sludge having the composition shown in Table 4 (substance previously dried to a moisture content of 5% or less by a dryer, average particle size of 30 μm, 50 g) is arranged as the substance to be heated 2 and the atmosphere. Nitrogen (partial pressure of oxygen contained as an impurity is 10 ⁻⁴ MPa) is circulated as gas 5, and a microwave of 24 GHz is oscillated from the gyrotron 4 to irradiate the heated material 2 with microwaves of 24 GHz (output) (400W, multimode), the temperature was rapidly raised to 1200 ° C. in 30 minutes, and heat treatment was performed for 30 minutes at that temperature. In addition, the thermocouple 7 was used for temperature measurement, and it measured in the state which the powder and the thermocouple temperature-measurement part which consisted of the mixture of lobe river powder ore and powder coke fully contacted.

  Table 11 shows the composition and Fe reduction rate of the neutralized sludge after the microwave heat treatment. As is clear from the results shown in Table 11, in Example 5, hematite (or goethite) in the neutralized sludge is reduced to the level of wustite (estimated from the Fe reduction rate and X-ray diffraction analysis results). I was able to. Further, by using the neutralized sludge after the microwave heat treatment as a raw material for a sintering machine at an ironworks, it was possible to reduce fuel (powder coke, anthracite, etc.) used in the sintering machine.

(Comparative Example 1)
The microwave heat treatment according to Comparative Example 1 was performed using the same microwave heat treatment apparatus as in FIG. 1 shown in FIG.
In the applicator 1, a hematite reagent (special grade: purity 99.0% or more, 100 g) is arranged as the material to be heated 2, hydrogen is circulated as the atmosphere gas 5, and a 2.45 GHz microwave is oscillated from the magnetron 3. When microwave irradiation was performed with the same output as in Example 1 (output 400 W, multimode), the temperature increased only to 40 ° C. even after 60 minutes of irradiation. In addition, the thermocouple 7 was used for temperature measurement, and it measured in the state which the powder of the hematite reagent and the thermocouple temperature-measurement part contacted sufficiently.
Regarding the hematite reagent after the microwave heat treatment, the reduction did not proceed at all.

(Comparative Example 2)
Using the same microwave heat treatment apparatus as FIG. 1 shown in FIG. 7, the microwave heat treatment according to Comparative Example 2 was performed.
In the applicator 1, lobe river powder ore (particle size 1 to 3 mm, 150 g) having the composition shown in Table 2 is arranged as the material to be heated 2, and nitrogen (partial pressure of oxygen contained as an impurity) is used as the atmosphere gas 5. 10 ⁻⁴ MPa) was circulated, and a 2.45 GHz microwave was oscillated from the magnetron 3 and was irradiated with microwaves at the same output (output 400 W, multimode) as in Example 2; Therefore, the heat treatment was performed for 30 minutes at that temperature. In addition, the thermocouple 7 was used for temperature measurement, and it measured in the state which the powder of the lobe river powder ore and the thermocouple temperature-measurement part contacted sufficiently.

  Table 12 shows the composition and Fe reduction rate of the lobe river powder ore after the microwave heat treatment. As is clear from the results shown in Table 12, in Comparative Example 2, compared with Example 2, it took time to raise the temperature, so the entire processing time was significantly increased. In addition, hematite (or goethite) in lobe river powder ore was only partially reduced to magnetite (estimated from Fe reduction rate and X-ray diffraction analysis results).

(Comparative Example 3)
Using the same microwave heat treatment apparatus as FIG. 1 shown in FIG. 7, the microwave heat treatment according to Comparative Example 3 was performed.
In the applicator 1, lobe river powder ore (particle size 1 to 3 mm, 150 g) having the composition shown in Table 2 is arranged as the material to be heated 2, and hydrogen is circulated as the atmosphere gas 5, and 2.45 GHz from the magnetron 3. When microwave irradiation was performed with the same output (output 400 W, multimode) as in Example 3 and the temperature was raised to 900 ° C. in 85 minutes, heat treatment was performed for 30 minutes at that temperature. . In addition, the thermocouple 7 was used for temperature measurement, and it measured in the state which the powder of the lobe river powder ore and the thermocouple temperature-measurement part contacted sufficiently.

  Table 13 shows the composition of the lobe river powder ore after the microwave heat treatment and the Fe reduction rate. As is apparent from the results shown in Table 13, in Comparative Example 3, compared with Example 3, it took a long time to raise the temperature, so that the entire processing time was significantly increased. Moreover, although it was possible to reduce the hematite (or goethite) in the lobe river powder ore to almost the metallic iron state, the reduction rate was smaller than that in Example 3.

(Comparative Example 4)
The microwave heat treatment according to Comparative Example 4 was performed using the same microwave heat treatment apparatus as in FIG. 1 shown in FIG.
In the applicator 1, the lobe river powder ore having the composition shown in Table 2 (particle size 1 to 3 mm, 150 g) and the powdered coke having the composition shown in Table 9 (particle size 3 mm or less, average particle size 0.7 mm) , 38 g) (lobe river fine ore 100: fine coke 25 as mass ratio) and nitrogen (the partial pressure of oxygen contained as impurities is 10 ⁻⁴ MPa) as an atmospheric gas 5 circulates, When a microwave of 2.45 GHz was oscillated from the magnetron 3 and was irradiated with microwaves at the same output (output 400 W, multimode) as in Example 4, the temperature was raised to 1300 ° C. in 40 minutes. Heat treatment was performed for a minute. In addition, the thermocouple 7 was used for temperature measurement, and it measured in the state which the powder of the mixture of the lobe river powder ore and the powder coke, and the thermocouple temperature-measurement part fully contacted.

  In Table 14, the composition and Fe reduction | restoration rate are shown about the mixture of the lobe river powder ore and the powder coke after a microwave heat processing. As is apparent from the results shown in Table 14, in Comparative Example 4, it was possible to quickly reduce most of the hematite (or goethite) in the lobe river powder ore to the state of metallic iron. The treatment time was slightly longer than in Example 4, and the Fe reduction rate was small.

(Comparative Example 5)
The microwave heat treatment according to Comparative Example 5 was performed using the same microwave heat treatment apparatus as in FIG. 1 shown in FIG.
In the applicator 1, neutralized sludge having the composition shown in Table 4 (substance previously dried to a moisture content of 5% or less by a dryer, average particle size of 30 μm) is disposed as the substance to be heated 2, and the atmosphere gas 5 As a result, nitrogen (the partial pressure of oxygen contained as an impurity is 10 ⁻⁴ MPa) was circulated, and a 2.45 GHz microwave was oscillated from the magnetron 3, and the same output (output 400 W, multimode) as in Example 5 was used. When wave irradiation was performed, the temperature was raised to 1200 ° C. in 30 minutes, and heat treatment was performed at that temperature for 30 minutes. In addition, the thermocouple 7 was used for temperature measurement, and it measured in the state which the powder of neutralization sludge and the thermocouple temperature-measurement part contacted sufficiently.

  Table 15 shows the composition of the neutralized sludge after the microwave heat treatment and the Fe reduction rate. As is apparent from the results shown in Table 14, in Comparative Example 5, the reduction rate is small compared to Example 5, and hematite (or goethite) in the neutralized sludge is reduced only to the extent of magnetite (Fe reduction). Rate and X-ray diffraction analysis result).

  DESCRIPTION OF SYMBOLS 1 ... Applicator (reactor), 2 ... Heated material, 3 ... Magnetron, 4 ... Gyrotron, 5 ... Atmospheric gas, 6 ... Exhaust gas, 7 ... Thermocouple.

Claims (6)

  The iron oxide-containing substance is heated by irradiating the iron oxide-containing substance containing at least one of hematite and goethite with a microwave having a frequency in a range of 20 to 30 GHz, and the iron oxide-containing substance is heated. A method for reducing an iron oxide-containing substance by microwave heating, comprising reducing iron oxide containing at least one of the hematite and goethite contained in the substance.   The method for reducing an iron oxide-containing substance by microwave according to claim 1, wherein the microwave irradiation to the iron oxide-containing substance is performed in a state of coexisting with a reducing agent.   The iron oxide by microwave heating according to claim 2, wherein the reducing agent is a carbon-containing substance, and the mixture obtained by adding the reducing agent to the iron oxide-containing substance is irradiated with microwaves. Reduction method of contained substances.   4. The microwave-containing iron oxide-containing material according to claim 2, wherein the reducing agent is a reducing gas, and the microwave irradiation to the iron oxide-containing material is performed in the reducing gas. Reduction method.   The iron oxide-containing substance is reduced by microwave heating according to any one of claims 1 to 4, and the reduced iron oxide-containing substance is used as a raw material in a sintered ore production process. The manufacturing method of the raw material for sinter ore production.   A blast furnace characterized in that the iron oxide-containing substance is reduced by microwave heating according to any one of claims 1 to 4, and the reduced iron oxide-containing substance is used as a raw material in a blast furnace process. Raw material manufacturing method.

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