JP5177160B2 - Slag particulate identification method and carbonation treatment apparatus - Google Patents

Description

  The present invention relates to a method for identifying slag fine particles from a fine particle mixture of slag fine particles containing free lime on the surface and fine particles of a type different from the slag fine particles, and a carbonation treatment apparatus used in the method.

  In the metal refining industry, there is often a need for the type and particle size distribution of various fine particles (for example, particles having a diameter of several μm to several hundred μm) generated in the refining process. The types and particle size distributions of various types of particles are, for example, the purpose of analyzing the dust collected in the dust collector of the factory building and grasping the time transition of smoke leakage and dust generation status in the factory Is needed for. For this purpose, since it is necessary to analyze a large number of fine particle samples, a simple and inexpensive method for analyzing fine particles is desired.

  Here, generally used analysis methods of fine particles include, for example, analysis using radiation such as chemical analysis and fluorescent X-ray analysis, sieving method, analysis using laser diffraction particle size distribution analyzer, particle There are various methods such as image processing measurement.

  Chemical analysis is a reliable (highly accurate) analysis method, but it is not a simple method because it takes a lot of time and requires a minimum mass of about 10 g of the sample necessary for the analysis. In addition, the particle size distribution cannot be measured.

  Analysis using radiation can be performed even with a very small amount of sample, but since radiation is used, the apparatus becomes large and cannot be said to be an inexpensive method. In addition, the particle size distribution cannot be measured.

  The sieving method can easily measure the particle size distribution of relatively coarse particles. However, fine particles having a diameter of 40 μm or less tend to adhere to the mesh of the sieve, and the particles are also difficult to fall due to air resistance. Therefore, this method cannot separate fine particles having a diameter of 40 μm or less. The type of fine particles cannot be identified unless combined with other methods.

  Analysis using a laser diffraction particle size distribution meter can easily and accurately measure the particle size distribution of fine particles. However, this method is not an inexpensive method because the measuring device is expensive. Also, the type of fine particles cannot be identified.

  In particle image processing measurement, an image of a particle group photographed through a lens such as an optical microscope is image-processed to identify particles, and the size, shape, and brightness of each identified particle (in the case of a color image, color And the like (for example, the diameter of an equivalent circle if it is a dimension, roundness if it is a shape, average brightness if it is lightness, etc.) can be obtained (see, for example, Patent Document 1). A histogram (brightness histogram) can also be obtained by summing up individual particles for each specific measurement (for example, brightness). Thus, the particle size analysis technique is inexpensive and simple, and a small amount of sample (for example, several tens of μg) is required for analysis.

  However, in particle image processing measurement, in order to determine the type of particle, preliminary information on lightness is required, that is, for example, particles with low lightness are coal and particles with high lightness are alumina or the like. In advance, information that associates the types of particles that can be included in the sample particles with the brightness is required. Conversely, if such information is obtained in advance, the type of particle can be easily identified using the representative brightness of each particle.

  For this reason, particle image processing measurement is a simple and inexpensive particle analysis method, and is an effective method that best meets the needs of the particle analysis method described above. Therefore, it is desirable to apply particle analysis by image processing measurement to as many objects as possible.

JP 11-132934 A JP 2005-97076 A JP 2001-26470 A JP-A-6-92696 Japanese Patent Laid-Open No. 7-172882 Japanese Patent Laid-Open No. 10-158043 JP 2003-335558 A

  However, even with the same particle type, there are fine particles whose brightness varies greatly, and such a fine particle has a problem that the particle type cannot be identified only by lightness information. Typical examples of such fine particles include slag produced and used in the metal refining industry, particularly slag fine particles containing free lime on the surface of steelmaking slag and the like in the steel industry.

  Steelmaking slag is usually subjected to a treatment called aging that is left outdoors for several weeks to several months. By this aging, the brightness of steelmaking slag fine particles gradually becomes monochromatic from a dark color. In addition, since the aging period applied to the steelmaking slag varies depending on the application, the surplus area of the slagyard, and the like, the lightness of the steelmaking slag changes greatly according to the progress of aging. In this way, in the slag fine particles containing free lime such as steelmaking slag, the aging progress of the obtained sample is not constant, so the representative brightness of individual particles is greatly different between the particles, so even by image processing measurement, It was difficult to identify slag particulates from the particulate mixture as a sample only by the brightness information.

  Therefore, the present invention has been made in view of the above problems, and in a method for identifying slag fine particles containing free lime on the surface from a fine particle mixture as a sample, particle image processing measurement is applied, It is an object of the present invention to make it possible to easily identify slag fine particles based only on the brightness information of particles.

  As a result of intensive studies to solve the above problems, the present inventors contacted each fine particle in the fine particle mixture of the sample with a minute volume of carbonated water, and the moisture in the minute volume of carbonated water By subjecting the fine particles that were in contact with carbonated water to dry removal as it is, calcium carbonate is selectively generated or deposited only on the free lime contained in the slag fine particles, and free lime is contained on the surface. The lightness of the surface of only the slag fine particles to be reduced can be lightened, thereby finding that the slag fine particles containing free lime on the surface can be distinguished from other types of fine particles, and to complete the present invention based on this finding It came.

  That is, according to the present invention, there is provided a method for identifying slag fine particles that distinguishes the slag fine particles from a fine particle mixture composed of slag fine particles containing free lime on the surface and fine particles of a type different from the slag fine particles. A first brightness measurement step for measuring the representative brightness of each fine particle by performing image processing on an image obtained by imaging all the fine particles in the fine particle mixture, and a water vapor having a carbon dioxide gas concentration of 1 mol% or more and a saturated water vapor amount A carbonation treatment step in which water droplets are brought into contact with at least one or more of each fine particle for at least one hour to each of all the fine particles in the fine particle mixture placed in a room temperature gas containing A drying step for drying the fine particles after the processing step, and image processing for an image obtained by imaging all the fine particles in the fine particle mixture after the drying step. A second brightness measurement step for measuring the representative brightness of each fine particle, and the representative brightness measured in the second brightness measurement step is higher than the representative brightness measured in the first brightness measurement step. A method for identifying slag fine particles, comprising: identifying the fine particles having a degree as slag fine particles containing free lime on the surface.

  Further, according to the present invention, there is provided a method for identifying slag fine particles for identifying the slag fine particles from a fine particle mixture comprising slag fine particles containing free lime on the surface and fine particles of a type different from the slag fine particles, Carbonation in which at least one water droplet is brought into contact with each of all the fine particles in the fine particle mixture placed in a normal temperature gas containing 1 mol% or more of carbon dioxide gas and saturated water vapor for at least one hour. A treatment step, a drying step of drying the fine particles after the carbonation treatment step, and an image processing performed on an image obtained by imaging all the fine particles in the fine particle mixture after the drying step. A brightness measurement step for measuring representative brightness, and fine particles having a brightness of a predetermined value or more among the representative brightness measured in the brightness measurement step are allowed to play on the surface. Including an identification step of identifying a slag particles containing lime, identification method of the slag particles are provided.

  Here, in the identification method of the slag fine particles, examples of the slag fine particles containing free lime on the surface include steelmaking slag.

  Further, in the method for identifying slag fine particles, the fine particle mixture may consist of falling dust generated from an iron manufacturing plant by a blast furnace method.

In the method for identifying slag fine particles, in the carbonation treatment step, each fine particle is contained in a CO ₂ incubator maintained in a room temperature gas atmosphere containing carbon dioxide gas having a concentration of 1 mol% or more and water vapor having a saturated water vapor amount. It is preferable to stand still.

Moreover, in the identification method of the slag fine particles, a water tank is disposed in the CO ₂ incubator, and a set temperature of a heater installed in the water tank is maintained at a temperature higher than a set temperature of an atmosphere in the CO ₂ incubator. You may control as follows.

Further, in the identification method of the slag particles, and in the carbonation process, the CO ₂ incubator, the substrate mounted with the respective minute particles are arranged horizontally, through the open portion of the CO ₂ incubator, and the substrate After spraying water droplets into the CO ₂ incubator using a atomizing nozzle in the horizontal direction, the CO ₂ incubator may be sealed to perform carbonation treatment.

Further, in the identification method of the slag particles, and in the carbonation process, during implementation of the carbonation process, through the open portion of the CO ₂ incubator, using an ultrasonic sprayer attached to the CO ₂ incubator water droplets May be sprayed into the CO ₂ incubator.

Further, in the identification method of the slag particles, the CO ₂ incubator, the arranged substrate placed each particle, by cooling the substrate, the water vapor in the CO ₂ incubator the on each particle Water droplets may be attached to the fine particles by condensation.

Moreover, according to the present invention, the carbonation treatment apparatus used in the above-described method for identifying fine slag particles is maintained in a normal-temperature gas atmosphere containing carbon dioxide gas having a concentration of 1 mol% or more and water vapor having a saturated water vapor amount. A CO ₂ incubator, a water tank installed in the CO ₂ incubator, a fine particle mixture which is installed above the water tank and includes slag fine particles containing free lime on the surface and different types of fine particles from the slag fine particles. There is provided a carbonation treatment apparatus comprising a substrate to be placed.

Here, the carbonation treatment apparatus controls the heater installed in the water tank and the set temperature of the heater so as to maintain a temperature higher than the set temperature of the atmosphere in the CO ₂ incubator. And may be further provided.

Further, the carbonation apparatus, the CO further comprising a atomizing nozzle which is attached to ₂ incubator, the CO ₂ incubator is sealable, said substrate is disposed horizontally at the CO ₂ incubator cage, wherein the atomizing nozzle, through the open portion of the CO ₂ incubator, the water droplets on the substrate and the horizontal direction may be sprayed into the CO ₂ incubator.

Further, the carbonation apparatus, the attached to a CO ₂ incubator, through the open portion of the CO ₂ incubator, water droplets may be a comprise further an ultrasonic sprayer for spraying the CO ₂ incubator.

In addition, the carbonation treatment apparatus may further include a cooling device that is installed at a lower portion of the substrate and cools the substrate so that water vapor in the CO ₂ incubator is condensed on the fine particles.

  According to the present invention, the lightness of slag fine particles containing free lime whose lightness varies depending on the progress of aging is made uniform by carbonation treatment, for example, for a small amount of specimen particles such as less than 10 mg, or particularly less than 100 μg. By applying particle image processing measurement, it is possible to easily identify slag fine particles based only on brightness information of individual particles.

It is explanatory drawing which shows the difference in the brightness of steelmaking slag type | system | group dust and iron-type dust. It is a flowchart which shows the flow of operation of the identification method of the slag microparticles | fine-particles which concern on the 1st Embodiment of this invention. Is an explanatory view showing an example of a CO ₂ incubator configuration used for the carbonation process in the same embodiment. In the embodiment, it is explanatory drawing which shows an example of the apparatus structure for maintaining the state in which the inside of a container is saturated with water vapor | steam. Is an explanatory diagram showing an example of an ultrasonic sprayer mounting device configured to CO ₂ incubator used for the carbonation process of the embodiment. It is explanatory drawing which shows an example of a structure of the apparatus which cools the prayer used for the carbonation process of the embodiment. It is a flowchart which shows the flow of operation of the identification method of the slag microparticles | fine-particles which concern on the 2nd Embodiment of this invention.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

[Difficulty in identifying steelmaking slag particles based on brightness information only]
First, before describing a preferred embodiment of the present invention, the difficulty of identifying steelmaking slag fine particles based only on lightness information will be described. As described above, the slag produced and used in the metal refining industry, in particular, the fine particles of slag containing free lime on the surface of the steelmaking slag, etc. in the steel industry, the lightness greatly varies even with the same particle type, It is very difficult to discriminate the particle type only from the brightness information.

(Definition of steelmaking slag)
Here, steelmaking slag refers to all slag generated in the steelmaking process based on the blast furnace method, other than blast furnace slag such as blast furnace granulated slag, blast furnace slow-cooled slag, blast furnace air-pulverized slag, for example, converter slag, There are dephosphorization slag and desulfurization slag. Steelmaking slag is mainly composed of oxides such as calcium oxide, silicon dioxide, aluminum oxide, and magnesium oxide. Unlike blast furnace slag, steelmaking slag usually contains a small amount (about several mass% or more) of iron oxide. Further, quick lime (CaO) is often added to steelmaking slag during refining for the purpose of adjusting the basicity of slag (CaO / SiO ₂ mass ratio). A part of the quicklime remains in the slag after refining is completed and the slag is cooled. Quick lime remaining in the slag is called free lime.

(Aging of slag)
If this free lime is contained in a large amount in the slag, it reacts with water or carbon dioxide in the atmosphere to expand the volume of the slag, increase the water absorption rate, etc., and reduce the strength of the slag. Therefore, it is necessary to sufficiently react the free lime in the slag with water or carbon dioxide in the atmosphere in advance. Aging is performed for this purpose. In particular, steelmaking slag is often used as a raw material for roadbed materials. However, if a large amount of free lime remains in the slag, the slag is used in the slag after it is used as the roadbed material. Slag expands due to the reaction of free lime with rainwater and carbon dioxide in the atmosphere, and the internal expansion causes the slag to break down and reduce the function as roadbed material. It is not preferable because it elutes. For this reason, steelmaking slag needs to be sufficiently aged before shipment to reduce the content of free lime in the slag.

  In addition, since blast furnace slag has little content of colored components, such as iron oxide, it is generally light color.

(Lightness of steelmaking slag)
Next, the brightness of the steelmaking slag will be described with reference to FIG. FIG. 1 is an explanatory diagram for comparing the difference in brightness between steelmaking slag dust and iron dust.

  In a steelmaking plant based on the blast furnace method, falling dusts of four types of dusts, mainly coal dust, iron dust, blast furnace slag dust, and steelmaking slag dust, are generated. Coal dust is dust derived from coal or coke containing carbon as a main component, and iron dust is iron ore, sintered ore, iron oxide powder (for example, steel making) containing iron oxide as a main component. Blast furnace slag dust is a soot derived from blast furnace granulated slag, blast furnace slow-cooled slag, etc. produced in the iron making process, containing silicon oxide and calcium oxide as main components. In addition, steelmaking slag dust is a soot derived from converter slag, dephosphorization slag, desulfurization slag, etc., which contains silicon oxide, calcium oxide and iron oxide as main components and is produced in the steelmaking process.

  Of these origins of dustfall, steelmaking slag contains iron oxide as described above, and is therefore generally darker than blast furnace slag immediately after being produced. Therefore, as shown in FIG. 1, steelmaking slag dust derived from steelmaking slag that has not sufficiently progressed to aging is equivalent to iron dust having the same magnetism (a property that can be magnetized when a magnetic force is applied). When compared only with lightness, it may be difficult to distinguish particles with relatively high lightness from steelmaking slag dust as iron dust.

  On the other hand, steelmaking slag needs to be aged in order to eliminate the inconveniences described above, and is usually left outdoors for several weeks to several months. During this aging period, calcium oxide (including free lime) present on the surface of the steelmaking slag is changed to white calcium carbonate by the action of moisture in the atmosphere such as carbon dioxide and rain. Therefore, the brightness of the slag surface gradually becomes lighter as aging progresses. Thus, as shown in FIG. 1, the brightness of the particles of the steelmaking slag dust derived from the steelmaking slag having sufficiently advanced aging is generally higher than that of the dustmaking derived from the steelmaking slag having insufficient aging. Degree. In this case, since the brightness of the steelmaking slag dust is higher than that of the iron dust, the steelmaking slag dust and the iron dust can be discriminated more clearly only by comparing the brightness.

  As described above, the brightness of the steelmaking slag dust is greatly changed according to the aging progress of the steelmaking slag. In addition, since the aging period applied to steelmaking slag varies depending on the usage and the storage amount of the slagyard, the aging rate of the obtained sample is constant for slag fine particles containing free lime such as steelmaking slag. Often not. For this reason, in steelmaking slag dust, the representative brightness of individual particles varies greatly among the particles. Therefore, it is difficult to identify steelmaking slag particles from a mixture of fine particles as a sample only by lightness information, even by image processing measurement. Met.

  Therefore, the present inventor has intensively studied a method for easily discriminating slag fine particles containing free lime on the surface from a fine particle mixture as a sample only by lightness information using image processing measurement.

[Study of means that can identify slag particles only by brightness information]
First, the inventor performs a predetermined pretreatment on the fine particle mixture as a sample, thereby selectively selecting only slag fine particles containing free lime on the surface of the fine particle mixture. If a light-colored (high lightness) substance can be generated, then each fine particle is imaged and subjected to image processing, whereby light-colored fine particles after pre-processing, or light-colored fine particles having a predetermined lightness or more, It was found that the surface can be distinguished from fine slag particles containing free lime.

  Next, the present inventor studied a method for generating a light-colored (high brightness) substance on the slag surface selectively only for slag fine particles containing free lime on the surface. Here, as described above, in aging applied to steelmaking slag and the like, a carbonation reaction is performed in which calcium oxide (including free lime) present on the slag surface is changed to white calcium carbonate. However, aging is usually performed by leaving slag outdoors (natural aging), which requires a long time of at least several weeks, so secure a place to keep slag for a long time. It must be done and requires a large area for slag storage.

(Acceleration technology for aging)
Therefore, various techniques for accelerating aging by accelerating the reaction of free lime contained in the slag (accelerated aging) have been proposed from the viewpoint of reducing the area of the necessary slag storage area.

  For example, Patent Documents 2 to 4 disclose a method in which high-concentration carbon dioxide (gas or aqueous solution) and water (liquid or water vapor) are brought into contact with slag. In this method, aging is performed by reacting high-concentration carbon dioxide and water with free lime existing on the slag surface and inside to produce calcium carbonate on the slag surface and inside the slag.

  For example, Patent Document 5 discloses a method of reacting dilute sulfuric acid with slag. This method is intended to obtain the same effect as aging by reacting dilute sulfuric acid with free lime present on the slag surface and inside to produce calcium sulfate on the slag surface and inside.

  For blast furnace slag that contains almost no free lime, aging for reacting free lime is not performed. For the purpose of coating, there are cases where various reactions occur on the slag surface (surface reaction technology).

  As an example of such a surface reaction technique, for example, in Patent Document 6, a granulated slag is produced by bringing a sulfate aqueous solution (for example, an aluminum sulfate aqueous solution, a magnesium sulfate aqueous solution or an ammonium sulfate aqueous solution) into contact with molten blast furnace slag. A method is disclosed. This method coats the surface of granulated blast furnace slag by depositing the sulfate on the slag surface and inside immediately after solidification of the slag. This coating layer is redissolved in cooling water after slag cooling. In this case, Ca in the slag does not react particularly.

  Further, for example, Patent Document 7 discloses a method in which carbon dioxide gas or carbonated water is sprayed on and contacted with blast furnace granulated slag and then laminated. In this method, immediately after solidification of slag, calcium carbonate is generated on the slag surface to coat the surface of granulated blast furnace slag.

  As described above, for aging of slag (particularly steelmaking slag), not only natural aging, but also various technologies similar to accelerated aging have been proposed.

  Therefore, the present inventor can apply the known aging technique proposed in the above literature as a means for lightening the slag surface such as carbonation reaction of free lime existing on the slag surface in the present invention. We examined whether or not.

(1. Method of bringing dilute sulfuric acid into contact with slag)
If dilute sulfuric acid of about 0.1% by mass or more is brought into contact with the steelmaking slag by using this method, a white (light color) calcium sulfate layer is surely rapidly formed on the slag surface. Since this calcium sulfate is hardly soluble in water, it can exist as a coating layer on the slag surface. However, other fine particles, such as iron powder and iron oxide, are easily dissolved as ions in a strong acidic aqueous solution (dilute sulfuric acid), and the fine particles to be identified themselves are greatly reduced or lost. The state is greatly damaged. Therefore, the method of bringing dilute sulfuric acid into contact with slag is not suitable as a method of distinguishing slag fine particles from other fine particles.

(2. Method of bringing sulfate aqueous solution into contact with slag)
As in this method, an aqueous solution of a salt (Na ₂ SO ₄ , MgSO _4, etc.) of a strong acid (H ₂ SO ₄ ) and a strong base (NaOH, Mg (OH) _2, etc.) is slag (free lime is CaO + H in water). ₂ O → Ca (OH) ₂ reaction, which is present in the state of hydroxide), the white CaSO 4 production rate is small, so the effect of lightening is small. In addition, since a step for washing (washing) the salt adhering to the surface of the fine particles brought into contact with the sulfate aqueous solution is necessary, for extremely small samples (for example, about 100 μg or less) Since most of this may flow out, it is not suitable.

(3. Method using natural aging)
In an outdoor environment or a room that simulates the outdoor environment, if you try to adopt a method of aging naturally by simply leaving the sample and using rainwater and carbon dioxide in the atmosphere, let the aging progress sufficiently For this purpose, a period of at least several weeks is required and there is a problem that it takes too much time. In addition, since the amount of the sample to be identified for the slag fine particles according to the present invention is very small, there is also a problem that the sample particles are likely to be dissipated when processed for a long time. Therefore, it is difficult to use natural aging in the method for identifying slag fine particles according to the present invention.

(4. Method using accelerated aging)
As described above, various methods have been proposed for the accelerated aging technique. The principle common to these techniques is that free water contained in the slag is brought into contact with water having a high carbonic acid concentration and slag. This is to promote the carbonation reaction of lime (CaO + H ₂ O → Ca (OH) ₂ , Ca (OH) ₂ + CO ₂ → CaCO ₃ + H ₂ O). As a method of supplying water at this time, there are the following methods.

1) Method of Using Slag Moisture The first method is a method of using water confined inside or between slag chunks (usually referred to as “slag moisture”). This method is effective only when the slag lump is large or laminated in a large amount, and cannot be used for a small amount of fine particles which are objects of identification in the present invention.

2) Method of condensing high-temperature water vapor The second method is a method in which high-temperature water vapor is brought into contact with low-temperature slag and water vapor is condensed on the slag surface to obtain liquid water. This method cannot be used unless the heat capacity of the slag is large. Since the object of identification in the present invention is a small amount of fine particles, even if the fine particles are set to a low temperature in advance, the temperature of the fine particles rises to a high temperature atmosphere in a very short time due to contact with the high temperature atmosphere, and water vapor is generated. It can hardly be condensed. Therefore, this method cannot be applied to the identification of slag fine particles of the present invention.

3) Method of using liquid water The third method is a method of spraying liquid water from the laminated slag or immersing the slag in liquid water. This third method can be further classified into two according to the difference in the CO ₂ supply method.

3-1) Batch method The first method is to produce carbonated water in which CO ₂ is dissolved in excess of the saturated dissolved amount of CO _{2 in} the atmosphere. There is a method of bubbling in large quantities.) This is a method (batch method) in which this carbonated water is brought into contact with slag in the atmosphere. In the case of this batch type, the amount of carbonate ions in carbonated water is defined by the amount of carbon dioxide dissolved in advance, and decreases monotonously by contact with slag.

3-2) Continuous method The second method is to continue to supply carbonic acid to the water while the carbonated water and the slag are in contact (as an example of the realization method, the carbonic acid is formed on the slag in contact with the water. There is a method of continuously supplying a gas flow.) Method (continuous type). In the case of this continuous type, carbonate ions lost due to reaction with slag in carbonated water are compensated by dissolving the continuously supplied carbon dioxide gas in water, so carbonate ions in carbonated water are extremely reduced. Never do.

<Details of carbonation reaction process>
Here, before examining whether the method for accelerating aging of slag using liquid water as described above is applicable to the method for identifying slag particulates of the present invention, carbonation of free lime in slag Details of the reaction process will be described.

  Free lime in slag is much easier to elute in water (ionized in the form of ionized calcium hydroxide) than calcium oxide (CaO) chemically bonded to other oxides in slag. Reacts easily to produce calcium carbonate. Since the solubility of calcium carbonate in water is about 0.6% by mass, the precipitation state of calcium carbonate varies depending on the following three conditions.

  The first condition is a case where the carbonate ion in water is almost consumed and the calcium carbonate concentration is 0.6% by mass or less. In this case, most of the generated calcium carbonate is dissolved in water. doing.

  The second condition is when the calcium carbonate concentration exceeds 0.6% by mass in a state where carbonate ions in the water are almost completely consumed. In this case, the calcium carbonate concentration is reduced to 0.6% by mass. When it reaches, the calcium carbonate salt generated thereafter is precipitated as a solid. The place of precipitation is determined by the flow field of water and the concentration distribution of calcium carbonate. For example, if the flow of water is strong, the calcium carbonate salt may be deposited at a place far from the place where free lime is eluted.

The third condition is that the carbonate ion in the water is excessively consumed (for example, in the case of a system in which the amount of carbonate in the water is sufficiently large or the consumed carbonate ion is replenished). In this case, most of the calcium carbonate produced by elution of free lime is chemically converted to calcium hydrogen carbonate (CaCO ₃ + CO ₂ + H ₂ O⇔Ca (HCO ₃ ) ₂ equilibrium) In the reaction formula, due to Le Chatelier's law, the equilibrium moves in the direction of reducing excess carbonate ions). In this case, since the produced calcium bicarbonate has high solubility in water, the salt of the solid does not precipitate.

By the way, in the carbonation of slag, if the above reaction form is taken into consideration, the free lime existing in the vicinity of the surface of the slag does not take a form that changes to calcium carbonate on the spot and remains on the surface of the slag as it is. . In addition, if the carbonated water and slag are left in contact, a dense layer of free lime (ionized ions of calcium hydroxide) eluted from the slag surface covers the slag and reacts with surrounding carbonate ions at this location. In principle, it is possible that the generated calcium carbonate salt is deposited near the elution site of free lime, and as a result, the solid calcium carbonate layer covers the surface of the slag from which the free lime is eluted. However, the occurrence of such a phenomenon is limited to the CO ₂ concentration and the calcium carbonate concentration in a fairly narrow range of water as in the second condition described above. In practice, the content of free lime in individual slags varies and it is difficult to know the amount in advance, so the second condition can be realized for most slag particles at the same time. Almost impossible.

  Therefore, when slag is carbonized during slag acceleration aging, which is generally performed, a large amount of slag (relatively high uniformity with different types of slag and aging) is contacted with a large amount of carbonated water. Calcium carbonate is adhered to the slag surface by any of the following mechanisms.

The first mechanism is a mechanism limited to the batch type. In this first mechanism, the amount of CO ₂ initially supplied to the water is set lower than the total amount that can be consumed by free lime in the slag, and the total amount of carbonate ions generated by the supplied CO ₂ is determined. The amount of water supply is set so that the total amount of calcium carbonate production calculated is equal to or greater than the solubility. As a result, even though there is a variation in the amount of free lime eluted from individual slags, calcium carbonate produced in carbonated water through contact between carbonated water and slag in the carbonated water as a whole is more soluble than the solubility of calcium carbonate in water. Therefore, the generated calcium carbonate is deposited on the surrounding slag surface as a solid salt.

  However, in the case of this first mechanism, the location where free lime is eluted and the location where calcium carbonate is deposited generally do not match.

The second mechanism is a mechanism capable of both batch type and continuous type. In this second mechanism, CO ₂ is excessively supplied into the water. As a result, the rate of calcium carbonate production reaction is improved. When carbonated water and slag are brought into contact with each other in this state, most of the eluted free lime is dissolved in water as calcium bicarbonate. In this state, the water in which the calcium carbonate is dissolved is kept in the vicinity of the slag without flowing out as much as possible out of the system, and then the water is evaporated. As the water evaporates, the concentration of calcium hydrogen carbonate in the water increases and eventually decomposes into calcium carbonate and CO ₂ (Ca (HCO ₃ ) ₂ ⇔CaCO ₃ + CO ₂ + H ₂ O ₂ ) Therefore, the equilibrium shifts in the direction of decreasing the excess calcium bicarbonate), so that the generated calcium carbonate is deposited on the surface of the nearby slag.

  However, in the case of this second mechanism, water is acidified because the carbonate ion concentration in water is high and the total amount of hydroxide ions derived from the free lime to be eluted is relatively small. For this reason, when aging progresses and an acid is brought into contact with the slag having a calcium carbonate layer formed on the surface to some extent, the calcium carbonate layer dissolves in the acid, so that aging may be reversed. Therefore, the second mechanism targets slag with little aging, or, among the free lime in the slag, only the highly reactive free lime is the target of carbonation, and the existing calcium carbonate. It is often carried out by bringing carbonated water and slag into contact with each other only for a short time (for example, several minutes) so that a large amount of the layer does not elute. Also in the case of this second mechanism, the location where free lime is eluted and the location where calcium carbonate is deposited generally do not match.

<Problem when Accelerated Aging is Applied to the Slag Fine Particle Identification Method of the Present Invention>
As described above, the method for identifying slag fine particles of the present invention is selective to only slag fine particles containing free lime on the surface, and for all slag fine particles containing free lime on the surface. The object is to generate a light-colored (high brightness) substance on the surface. Therefore, in this invention, it is necessary to change the free lime eluted on the slag surface into calcium carbonate as it is at the eluted site, and to deposit calcium carbonate at that site. That is, in the present invention, it is necessary to match the elution site of free lime with the deposition site of calcium carbonate.

  On the other hand, in the known accelerated aging, the free lime elution site and the calcium carbonate deposition site generally do not match in any of the mechanisms described above. This is because the purpose of the known accelerated aging is mainly to suppress the average elution of free lime from the product slag (ie, elution or carbonation prior to commercialization), so the slag is aged as a bulk. This is because it is not necessary to match the elution site of free lime and the deposition site of calcium carbonate in the first place. In addition, since the target of known accelerated aging is slag with high homogeneity and reproducibility generated by the same method in the same period, it is easy to optimize the carbonation treatment under certain working conditions, so that free lime It does not matter if the elution site and the calcium carbonate deposition site do not match.

  On the other hand, the object of the method for identifying slag fine particles of the present invention is a minute amount of fine particle mixture, and the fine particle mixture contains a large number of particle types, and even the same type of slag is in an aging state. There are some variations. Therefore, known acceleration aging cannot be simply applied to the method for identifying slag fine particles of the present invention. Specifically, when known acceleration aging is simply applied to the present invention, the following problems arise.

1) Problems in the case of applying a method (first mechanism) in which the amount of CO ₂ supplied is too small in a batch type. The object of the present invention is a fine particle mixture containing a dispersion of the slag aging state. . This is a point that is largely different from the known accelerated aging method. When the first mechanism is applied, for example, the fine particle mixture of the present invention includes slag particles that have sufficiently advanced aging. For such slag particles, any amount of CO _{2 is used.} Even if is supplied, the CO ₂ supply amount becomes excessive, and the calcium carbonate layer on the surface of the slag elutes in acidic or neutral water, thereby retreating aging. Moreover, since the target fine particle mixture has low homogeneity and reproducibility, it is difficult to estimate in advance the amount of free lime in the sample of the obtained fine particle mixture. Therefore, when the fine particle mixture of the present invention is used, it is difficult in the first place to set an excessive CO ₂ supply amount.

  In addition, since the free lime elution site and the calcium carbonate deposition site are different, the free lime eluted from the slag flows to another site, and calcium carbonate is generated at the site where it settled. There is a high possibility that calcium carbonate is deposited on the surface. In this case, there is a high possibility of misidentifying other types of particles (particles other than slag) on which calcium carbonate is deposited as slag.

2) Problems when the method of contacting carbonated water containing excess CO ₂ with slag (second mechanism) is applied. When the second mechanism is applied, slag aging in the target fine particle mixture is applied. Since the state varies from particle to particle, it is almost impossible to perform carbonation treatment only on particles having a low degree of aging. In addition, in order for a calcium carbonate layer to be formed on the surface of particles having a low degree of aging and for the particles to be sufficiently light-colored, it is the same as lightening a coarse slag mass having a low degree of aging. A contact time with a certain amount of carbonated water is required. Therefore, since the effect of lightening cannot be sufficiently obtained by processing for an extremely short time, it is difficult to apply to the method for identifying slag fine particles of the present invention.

  In addition, when a known accelerated aging method is applied, a method such as immersing the fine particles in carbonated water or dropping a large water droplet compared to the fine particles from above the fine particles is adopted. The slag can be contacted only with a large amount of carbonated water compared to the volume. Therefore, the calcium carbonate produced from the free lime eluted from the fine particles is not necessarily deposited on the fine particles, and for example, most of the calcium carbonate can be deposited on the wall of a container that performs the carbonation reaction. In this way, the free lime elution site and the calcium carbonate deposition site are different, so the free lime eluted from the slag flows to another site, and calcium carbonate is generated at the site where it settled. There is a high probability that calcium carbonate will be deposited on the surface of the particles. In this case, there is a high possibility of misidentifying other types of particles (particles other than slag) on which calcium carbonate is deposited as slag.

  As described above, the prior art only discloses a method for subjecting a large amount of slag to chemical treatment equivalent to aging, and is intended for a very small amount of slag fine particles to be used for analysis. There is no disclosure of a treatment method that can selectively lighten only the surface of slag fine particles containing free lime. Therefore, the method disclosed in the prior art cannot be simply used as a means for lightening the surface of a minute amount of slag fine particles to be subjected to image processing measurement.

(Method of selectively producing a light-colored substance only on the surface of slag fine particles containing free lime)
Therefore, the present inventor further studied a means for lightening the surface of a small amount of slag fine particles to be subjected to image processing measurement. As a result, the present inventor brought each fine particle in the sample fine particle mixture into contact with a minute volume of carbonated water, and the moisture in the minute volume of carbonated water was dried as it was on the fine particles with which the carbonated water was in contact. It has been found that a light-colored (high brightness) substance (calcium carbonate) can be selectively generated or deposited only on the surface of slag fine particles containing free lime on the surface by performing carbonation treatment to be removed. It was. Then, after performing the carbonation treatment, particle image processing measurement is performed on an image obtained by photographing the fine particles, so that the light-colored particles after the treatment is performed, or the light-colored fine particles having lightness of a predetermined level or more Can be distinguished from fine particles containing free lime on the surface. Hereinafter, more detailed contents of the carbonation treatment in the present invention will be described.

<Contents of carbonation treatment in the present invention>
In the carbonation treatment of the present invention, carbonated water containing excess CO ₂ is brought into contact with individual fine particles as fine water droplets of the same size as the fine particles, and then the individual fine particles are allowed to stand and dried. The contact method between the fine particles and the carbonated water may be such that the fine droplets of carbonated water are left in contact with the fine particles of the sample for a predetermined time (one hour or more).

  By performing such carbonation treatment, in the slag fine particles containing free lime on the surface, calcium hydrogen carbonate generated from the free lime eluted from the slag particles is contained in the water droplets adhering to the eluted slag particles. Since it is dissolved, in the process of evaporating the water droplets, calcium carbonate is deposited on the surface of the slag particles from which free lime is eluted.

  On the other hand, in the slag particles that do not contain free lime, the elution of the calcium carbonate layer that may be present on the surface layer of the slag particles is slight if the contact is made in a short time of about 1 hour. Although the calcium carbonate layer can be eluted if contacted for a longer period of time, since the eluted calcium carbonate is a small amount, the calcium carbonate is dissolved in the water droplets adhering to the eluted slag particles. In the process of evaporating, calcium carbonate is deposited on the surface of the slag particles to which water droplets adhere, so the difference between the initial state and the appearance is small.

  In addition, in slag particles with a small calcium carbonate layer, calcium oxide chemically bound to oxides in the slag elutes when contacted for a very long time, and may exhibit the same reaction as free lime. Under the weak acid derived from it, the elution rate is extremely slow compared to free lime, so the change in appearance is small and does not matter.

  Furthermore, in particles other than the slag particles described above, there are particles that can react with carbonic acid (for example, iron oxide), but the reaction rate is extremely slow compared to free lime under weak acid derived from carbonic acid. The change in appearance is small and does not matter.

  Therefore, if the carbonation treatment method in the method for identifying slag fine particles according to the present invention is used, the surface of only the slag particles containing free lime on the surface can be selectively lightened (bright).

  However, as in the carbonation treatment method described above, minute water droplets of the same size as slag fine particles and the like evaporate in a short time, so it has been conventional to maintain such minute water droplets for a long time. Was difficult.

  On the other hand, the present inventor, if the sample is allowed to stand in a container that holds a saturated water vapor pressure gas containing a high concentration of carbon dioxide gas at a constant temperature, is equivalent to the fine particles attached to the fine particles of the sample. It has been found that minute water droplets of a size can be retained for a long time.

  In addition, it has been difficult in the past to efficiently contact fine water droplets having the same size as the sample fine particles. For example, when atomized water droplets are sprayed in an open atmosphere, the drop speed of the water droplets is small, so that even when sprayed horizontally just above the sample, almost no water droplets adhere to the sample particles. On the other hand, if the sprayer is sprayed directly on the sample particles, the sample particles may be blown off, and in this case as well, it is difficult to attach minute water droplets to the sample particles.

On the other hand, the present inventor has found that water droplets can be attached to the surface of the fine particles with a high probability by spraying fine water droplets on the fine particles placed in the CO ₂ incubator.

As a specific method for spraying fine water droplets, for example, water droplets having a slightly large particle size (about several tens of μm) like a atomizing nozzle are left in a CO ₂ incubator in advance before carbonation treatment. It is good to spray on the fine particles. This is because the water droplets have a relatively large particle size, so that the water droplets can be easily maintained for a long time.

  On the other hand, finer water droplets (φ10 μm or less) may be sprayed during the carbonation treatment as in an ultrasonic sprayer. This is because the ratio of the water droplets lost by evaporation of the sprayed water droplets is higher than that when the atomizing nozzle is used, so that it is necessary to replenish the water droplets appropriately during the carbonation treatment.

Even when any of the above spraying methods is used, the fine particles reach the fine particles while the water droplets are scattered on the weak air flow in the CO ₂ incubator, and can adhere to the surface of the fine particles. There are no particular problems because fine water droplets adhering to the particles other than the fine particles are also very small.

  In addition, among the known accelerated aging methods, there is one that sprays spray water onto falling slag as a cooling means for high-temperature slag, but in this case, spray water is laminated with slag immediately after cooling, In most of the time when the slag comes into contact with water, the water is restrained in the slag mass or between the slag masses, or the slag is immersed in the water. Therefore, this method is greatly different from the spraying of fine water droplets in the carbonation treatment of the present invention.

  As described above, when fine water droplets having the same particle size as the sample fine particles are brought into contact with the sample fine particles, only the slag fine particles containing free lime on the surface are compared with the light-colored carbonic acid on the surface of the fine particles. A calcium layer can be generated and deposited. Hereinafter, the details of the identification method of the slag fine particles according to the present invention completed based on the above-described examination results will be described.

[Slag Fine Particle Identification Method According to First Embodiment of the Present Invention]
First, a method for identifying slag particulates according to the first embodiment of the present invention will be described with reference to FIG. FIG. 2 is a flowchart showing a flow of operations of the slag particulate identification method according to the first embodiment of the present invention.

(Definition of fine particle mixture)
First, as a premise for explaining a specific operation flow, the definition of the fine particle mixture in the present embodiment will be explained. The fine particle mixture in the present embodiment is mainly slag fine particles containing free lime on the surface produced in metal refining (hereinafter simply referred to as “slag fine particles”) and other types of slag fine particles different from the slag fine particles. A mixture with fine particles (hereinafter referred to as “other fine particles”). A specific example of such a fine particle mixture is falling dust generated from a steelmaking plant by a blast furnace method including slag fine particles and other fine particles.

  Examples of the slag fine particles in this case include, for example, slag produced in the metal refining process, particularly steel slag in the steel industry (converter slag, desulfurization slag, dephosphorization slag, desiliconization slag, secondary refining slag, etc.), electric furnace slag And fine particles such as converter slag in the copper refining industry.

  In addition, in the metal refining industry, the term “other fine particles” refers to a kind of fine particles that are easily generated in addition to slag fine particles containing free lime on the surface and that are easily mixed with these slag fine particles. Other fine particles include, for example, blast furnace slag (such as granulated slag, air-pulverized slag, slow-cooled slag), metal powder and metal oxide powder (iron powder, iron oxide powder, copper powder, copper oxide powder, sintered ore) Powder), coal powder, coke powder and the like.

(Collection of fine particle mixture)
In the method for identifying slag particulates according to the present embodiment, first, as shown in FIG. 2, the above-described particulate mixture is collected (S101). Hereinafter, the case where the fine particle mixture is dust falling from a steelmaking plant by the blast furnace method will be described as an example. The falling dust collection method in this embodiment is roughly classified into a wet method and a dry method. The wet method is a method of collecting the falling dust falling in an open container in which water is stored at the bottom, and collecting the dust together with the water in the container. As an apparatus using this wet method, for example, a commercially available deposit gauge can be used. In addition, when applying a wet method, it is necessary to isolate | separate dust particles from water and dry beforehand. The dry method is a method of sucking the dust falling to a dust collection port (for example, having a funnel shape) opened upward and collecting it in a membrane filter or the like. As an apparatus used for this dry method, for example, a continuous dust / dust meter described in JP 2008-224332 A can be used. In addition, when applying a dry method, it is desirable to isolate | separate particle | grains from a membrane filter beforehand. However, this process is not necessarily required if the number of collected particles is small and individual particles can be separated and recognized on the membrane filter.

(Processing samples for analysis)
Next, the sample for analysis (specific object) is processed. Specifically, the collected particulate mixture (for example, falling dust particles) is sprayed on the substrate (S103). At this time, the spraying amount is adjusted so that the particles do not contact each other. Further, it is not always necessary to process all of the collected fine particle mixture as an analytical sample (spread on the substrate), and a part of the collected fine particle mixture may be extracted and used as the analytical sample. However, in order to evaluate the influence of sample variation, it is preferable to use at least 100 particles of the fine particle mixture as the sample for analysis.

  The substrate on which the particles of the fine particle mixture are spread is not particularly limited as long as it has a flat shape and is difficult to chemically and electrically adhere to or adhere to the fine particle mixture. A simple metal plate or glass plate can be used.

  In addition, the fine particle mixture is usually coarse particles having a diameter of 10 μm or more in the case of falling dust, so that when falling dust particles are sprayed, it is possible to use free fall of the falling dust particles in the atmosphere. it can. Specifically, for example, the collected dust particles can be sprinkled with a soot and dropped onto the substrate from above, whereby the dust particles can be dispersed on the substrate.

  In the slag particulate identification method according to this embodiment, when the dry method is used as a particulate mixture (falling dust) collection method, the falling dust particles collected on the fluororesin membrane filter. Each membrane filter may be subjected to the following particle image processing measurement, carbonation treatment, and the like.

(Imaging the collected fine particle mixture)
Next, all the fine particles contained in the sample of the fine particle mixture created in step S103 are imaged, and a particle image that is an image of the fine particle mixture is generated (S105).

  For example, a commercially available microscope to which an illumination unit, an imaging unit, and the like are attached can be used to generate the particle image. Specifically, the particles of the fine particle mixture dispersed on the substrate are uniformly irradiated with light using an illumination unit. In the present embodiment, in order to measure the brightness of the particle image, it is preferable to set the illumination condition at the time of imaging the fine particle mixture so that the illuminance is always constant on the imaging surface. As illumination means, commercially available ring illumination for a microscope or the like can be used.

  Next, a sample of the fine particle mixture is imaged using an imaging means to generate a particle image. As an imaging method by this imaging means, for example, illumination is irradiated from the illumination means toward the particles of the fine particle mixture, and reflected light from the surface of the particles is received by the imaging means (or a lens attached to a microscope). The captured image (particle image) is generated by the imaging means. As an image pickup means at this time, a CCD type or CMOS type digital camera can be used.

  In addition, the brightness (representative brightness) of each dust particle is averaged within the size of the corresponding CCD element corresponding to each particle image, so that it is desirable for the measurement accuracy of the brightness of the particle that the number of pixels of the camera is large. Specifically, it is preferable to use an imaging means having pixels with a density that allows imaging of target particles with at least 9 pixels (monochrome camera). From the viewpoint of accurately recording the brightness of the particles, a monochrome camera is preferable. When a single-plate color camera (usually, a different color filter is applied to adjacent CCD elements) is used as the imaging means, the brightness value interpolated using the brightness of at least 4 pixels (CCD is Bayer). For example, it is necessary to use an imaging means having pixels with a density capable of imaging the target particles with at least 54 pixels. preferable. Further, in order to ensure the pixel density necessary for imaging the target particle, the particle may be enlarged and imaged through a lens such as a microscope if necessary.

(Particle image processing measurement: representative brightness measurement before carbonation)
Next, the representative brightness of each fine particle is measured by performing image processing on the particle image of the fine particle mixture captured in step S105. Specifically, particle image processing measurement generally performed is performed on the particle image of the fine particle mixture imaged in step S105 (S107). This particle image processing measurement can be performed using a particle image processing measurement function that is standardly installed in commercially available image processing software such as “ImageProPlus”.

  As a particle image processing measurement method, for example, first, imaging data (original image) is binarized using a predetermined brightness threshold value T. An example of a method for setting the lightness threshold value T in this case is as follows. That is, a certain lightness threshold value t1 is provisionally determined for a sample whose dust type is known (for example, a mixture of iron-based dust and steelmaking slag-based dust whose mixing ratio is known), and this lightness threshold value t1. And light color particles having lightness equal to or higher than this lightness threshold value t1 (in the above example, it should be steelmaking slag dust) and lightness less than lightness threshold value t1. It is discriminated from the dark-colored particles (in the above example, it should be iron dust). At this time, if the determination result is significantly different from the predetermined blending ratio, another lightness threshold value t2 is provisionally determined, and binarization is performed using this lightness threshold value t2. Distinguish between color particles and dark particles. By repeating the above operation, the lightness threshold value T can be set to the lightness threshold value T that provides the best separation (the determination result and the predetermined blending ratio substantially coincide). However, the method for setting the lightness threshold value T is not limited to the above method, and any method can be used as long as the lightness threshold value with the best separation can be obtained. Good.

  Since it is actually difficult to obtain completely uniform illuminance over the entire area of the field of view of the imaging means (camera), before the binarization, the brightness of the recorded pixel is set to the two-dimensional pixel The variation in illuminance in the image may be corrected by increasing or decreasing the correction value that is a function of the position. As a correction value calculation method in this case, for example, a gray test piece whose scattering light reflectance value is known in advance is photographed with the imaging system used in the present invention, and all of the images recorded at this time are recorded. A value obtained by subtracting the brightness of each pixel from the average brightness value of the pixel can be used as a brightness correction value for each pixel. If the correction value is sufficiently smaller than the dynamic range of the pixel, the error in this correction method is reduced. Further, it is desirable to make the illuminance on the photographing surface as uniform as possible so that the correction value becomes small.

  Next, from the connection relationship of the binarized brightness of adjacent pixels, an area where the same binarized brightness is continuous and independent of other areas is specified as an area where particles exist. Furthermore, if necessary, the area of each particle whose presence is specified may be calculated, and the center position of the particle and the diameter converted into an equivalent circle may be calculated. The calculated data such as the area, center position, and diameter of each particle are recorded in a storage means provided in the imaging system.

  The representative brightness of each particle is calculated by averaging the brightness of individual CCD elements located in the region where each particle exists in the captured image (original image) specified as described above.

(Carbonation treatment)
Next, carbonation of free lime eluted on the surface of the slag is performed by bringing fine water droplets into contact with each fine particle imaged in step S105 and subjected to image processing in step S107 for 1 hour or longer (S109). ). This method can also be used to evaluate the progress of aging using a fine particle specimen made of only steelmaking slag. That is, it can be determined that the higher the proportion of particles that lighten after carbonation, the lower the aging progress.

As a specific treatment method, for the fine particles of a sample placed in a CO ₂ incubator containing a high-concentration CO ₂ and a water vapor with a saturated water vapor amount at a room temperature, the same fine particles are used. A fine water droplet having a particle size of about a degree is contacted for 1 hour or more. A commercially available CO ₂ incubator at this time can be used, and the temperature and CO ₂ concentration in the incubator are automatically controlled to target values. A water tank is charged in the incubator and a shelf is provided, and a substrate on which the sample is placed is placed on the shelf.

<Carbonation treatment device>
Here, the CO ₂ incubator used for the carbonation treatment in the present embodiment will be described with reference to FIG. FIG. 4 is an explanatory diagram showing an example of the configuration of the CO ₂ incubator used for the carbonation treatment in the present embodiment.

As shown in FIG. 4, a CO ₂ incubator 10 (hereinafter referred to as “incubator 10”) according to this embodiment includes a container 11, a heater 12, and a CO ₂ gas cylinder 13 (hereinafter referred to as “cylinder 13”). ), A CO ₂ gas regulator (not shown; hereinafter referred to as “regulator”), a CO ₂ gas on-off valve 14 (hereinafter referred to as “on-off valve 14”), a thermometer 15, and a CO 2 _It mainly includes a _two densitometer 16 (hereinafter referred to as “densitometer 16”) and a control device 17.

The incubator 10 is a thermostatic chamber for culturing cultured cells and the like that require high CO ₂ concentration by controlling the temperature and CO ₂ concentration in the storage. In addition, many CO ₂ incubators have a structure in which a water tank is disposed in a semi-sealed container, and the water in the water tank maintained isothermally with the gas in the container by the gas in the container, Can be maintained at high humidity. Many types of such CO ₂ incubators are commercially available (for example, Yamato Scientific IT400). Also in the incubator 10 according to the present embodiment, a water tank 21 filled with water W and a shelf 22 on which the substrate 1 is placed are provided. As will be described later, the water tank 21 and the shelf 22 are disposed in a region surrounded by the heater 12, and the shelf 22 is provided above the water tank 21.

The container 11 is a semi-sealed container in which the outside air and the inside of the container 11 are connected by a very narrow channel 11a. In this semi-closed container, changes in the temperature of the gas inside the container 11 and changes in the internal pressure of the container 11 due to the supply of CO ₂ gas and the evaporation of water are alleviated by gas flow with the outside air through the narrow flow path 11a. Therefore, the container 11 does not need to have a pressure resistant structure. On the other hand, in the semi-sealed container, the gas flow through the narrow flow path 11a is minute except for the difference between the internal and external pressures of the container 11, so that the gas component difference and gas temperature difference greatly different between the inside and outside of the container 11 are maintained. be able to.

As described above, the heater 12 is disposed so as to surround the periphery of the water tank 21 filled with water W and the shelf 22 on which the substrate 1 is placed, and raises the ambient temperature in the container 11. The cylinder 13 is filled with CO ₂ gas maintained at a high pressure. The regulator is an apparatus that is connected to the cylinder 13 and obtains low-pressure CO ₂ gas that is adjusted to a constant pressure from the high-pressure cylinder 13. The on-off valve 14 supplies and stops the CO ₂ gas at a pressure adjusted by the regulator in the container 11 (particularly, in the region surrounded by the heater 12 in this embodiment) according to the opening / closing operation. I do.

The thermometer 15 is connected to the control device 17 (or a temperature controller that is a component of the control device 17), measures the temperature in the region surrounded by the heater 12, and transmits the measurement result to the control device 17. To do. The densitometer 16 is also connected to the control device 17 (or a CO ₂ concentration controller that is a component of the control device 17), measures the CO ₂ concentration in the region surrounded by the heater 12, and controls the measurement result. Transmit to device 17.

The control device 17 is connected to the heater 12, the on-off valve 14, the thermometer 15 and the concentration meter 16, and is based on the temperature measurement result transmitted from the thermometer 15 and the CO ₂ concentration measurement result transmitted from the concentration meter 16. Thus, the heater 12 and the on-off valve 14 are controlled so that the temperature and CO ₂ concentration in the container 11 (particularly, in the region surrounded by the heater 12 in this embodiment) are maintained constant. Further, the control device 17 may be a physically separate device having both a temperature control function and a CO ₂ concentration control function, and a physically separate temperature controller having a temperature control function and a CO ₂ concentration control. It may consist of a CO ₂ concentration controller having a function. In the latter case, the temperature controller is connected to the heater 12 and the thermometer 15, and the CO ₂ concentration controller is connected to the on-off valve 14 and the concentration meter 16.

<Target temperature>
The target temperature in the container 11 is the ambient temperature of the container 11 (room temperature) + 5 ° C. to 10 ° C. (specifically, the target temperature T is 0 ° C. (water freezing point) <T ≦ 50 ° C. (set temperature of the incubator) The upper limit) is preferred. In the case of a semi-sealed container such as the container 11, if the temperature difference from the outside air is large, the humidity tends to decrease when the outside air flows in, and there is a possibility that high humidity cannot be maintained. On the other hand, if the target temperature in the container 11 is lower than the temperature around the container 11, the temperature cannot be controlled without a cooler. Therefore, the structure of the apparatus and the logic of control become complicated, and the target before the sample is loaded. If the temperature is not set lower than the temperature, water droplets on the sample surface may evaporate immediately after charging, which is not preferable.

<Target CO ₂ concentration>
In the carbonation treatment in the present embodiment, accelerated aging is performed, so at least a concentration (1 mol%) of about 30 times the atmospheric CO ₂ concentration (0.03 mol%) is required. In this case, about one day is required for the carbonation treatment until a stable calcium carbonate layer is formed on the surface of the slag which is not aged at all. If the concentration is lower than this, the carbonation treatment requires more than one day, and the contact between the carbonated water and the fine particles during this period causes particularly high water-soluble particles (eg, granulated blast furnace slag, aged). Steelmaking slag) and the contact with water is not preferable because of adverse effects (such as elution of water-soluble components in the slag into water). Further, when the CO ₂ concentration is excessively high, the pH of carbonated water is excessively lowered, and the influence of elution of iron oxide or the like cannot be ignored. Therefore, the concentration is preferably 20 mol% or less, more preferably 10 mol% or less.

<Contact time between carbonated water and fine particles>
In order to generate a stable calcium carbonate layer on the surface of the slag that has not been aged at all (that is, to realize a calcium carbonate layer that is thick enough to have a light-colored appearance), The contact time between the carbonated water and the fine particles needs to be 1 hour or more at room temperature. In addition, if the fine particles and carbonated water are heated to a high temperature (for example, 100 ° C. or higher at high pressure), the carbonation reaction can be completed in a shorter time in principle, but other water-soluble fine particles Since the dissolution rate also rises rapidly, it becomes difficult to manage the contact time. Specifically, since the sample with an unknown particle composition rate is targeted, the optimal contact time cannot be set in advance) Is not preferable. As described above, the contact time between the carbonated water and the fine particles P is preferably 1 day (24 hours) or less.

<Humidity in the container>
The relative humidity in the container 11 is preferably 100%. Even if the relative humidity is about 90 to 95% that can be realized with a general CO ₂ incubator, it is applicable to the carbonation treatment of this embodiment. It is about time, not very suitable for long-time processing. Further, the relative humidity does not have to be 100% throughout the CO ₂ incubator, and there is no problem if water vapor is saturated in the vicinity of the surface of the sample fine particles.

<Method of maintaining the vessel in a state where water vapor is saturated>
Next, a method for maintaining the water vapor in a saturated state at least near the surface of the sample fine particles in the container 11 will be described with reference to FIG. FIG. 4 is an explanatory diagram showing an example of a device configuration for maintaining the inside of the container in a state where water vapor is saturated. 4, the detailed configuration of the incubator 11 shown in FIG. 3 (the heater 12, the cylinder 13, the on-off valve 14, the thermometer 15, the concentration meter 16, the control device 17, etc.) is omitted for convenience of explanation. It is.

In order to maintain a state where water vapor is saturated at least near the surface of the sample fine particles in the container 11, for example, as shown in FIG. 4, a water tank heater 31 (for example, a commercially available water tank) A ceramic heater) is installed, and the temperature of the water tank heater 31 may be set higher by about 5 ° C. to 10 ° C. than the atmospheric temperature in the CO ₂ incubator 11. Thereby, the state in which water vapor is saturated near the surface of the sample fine particles is obtained.

More specifically, the water temperature in the water tank 21 rises due to the heating by the water tank heater 31, and accordingly, the temperature in the CO ₂ incubator 11 gradually increases, and the water tank 21 responds to the water temperature. Steam (unsaturated with respect to the water temperature) is generated. The sample fine particles that contact the water vapor and the substrate 1 on which the sample is placed are heated by the temperature of the water vapor (that is, the temperature of the sample fine particles is slightly lower than the water vapor temperature). Therefore, just saturated water vapor is obtained on the surface of the sample fine particles. Since the inner wall surface of the container 11 has the lowest temperature in the container 11, water vapor is condensed on the inner wall surface, and the inside of the container 11 is slightly dehumidified.

Here, the reason why the water vapor saturated on the surface of the sample fine particles is obtained in the present embodiment will be described. Inside the CO ₂ incubator 11, gas circulation is normally performed, so that the bulk gas temperature is kept almost constant regardless of the temperature of the water tank 21. The fine particles P that are the specimen and the substrate 1 are heated by the gas in the CO ₂ incubator 11, but since the heat capacity is small, the surface temperature of the fine particles P is substantially equal to the gas bulk temperature in the CO ₂ incubator 11. . On the other hand, the water vapor generated from the water tank 21 is an amount corresponding to the saturated vapor pressure at the surface temperature (> gas bulk temperature) of the water tank 21, and thus is supersaturated in the very vicinity of the water tank 21. This is because the CO ₂ gas supplied into the CO ₂ incubator 11 is normally dust-removed, so the super-saturated steam in the gas in the CO ₂ incubator 11 has few nuclei for forming water droplets and requires a high degree of supersaturation. This is because condensation can be achieved only by homogeneous nucleation. However, excess water vapor in the gas in the incubator 11 is condensed and removed from the gas on the inner wall of the CO ₂ incubator 11 having a slightly lower temperature than the surface of the fine particles P and a large surface area. This is because the condensation of water vapor on the inner wall of the CO ₂ incubator 11 is heterogeneous nucleation utilizing the wall surface, so that it is much easier on the inner wall surface than homogeneous nucleation in gas (ie, This is because water vapor can be condensed (with a low degree of supersaturation). In addition, the CO ₂ incubator 11 has a structure in which the difference between the temperature of the inner wall and the bulk gas temperature is usually in a small range of about 1 ° C. at most, so the humidity of the bulk gas is kept almost 100%. It is. Therefore, the humidity is maintained at almost 100% even on the surface of the fine particles P having the same temperature as the bulk gas temperature.

Further, in the case of the present embodiment, the bulk gas temperature in the CO ₂ incubator 11 continues to rise during the process, but the carbonation process according to the present embodiment is a process for a relatively short time. As long as the above-mentioned preferable processing temperature range can be maintained, there is no problem in processing.

  In the present embodiment, a water temperature meter 32 is provided for measuring the water temperature in the water tank 21 heated by the water tank heater 31, and this water temperature meter 32 is connected to a water temperature control device 33 such as an electronic thermostat. Yes. The water temperature control device 33 is also connected to the water tank heater 31, and heats the water in the water tank 31 when the water temperature in the water tank 21 falls below the target temperature based on the measurement result by the water temperature gauge 32. In addition, the water tank heater 31 is controlled.

<Method of generating fine water droplets and method of attaching water droplets to fine particles>
Next, a method for generating fine water droplets and a method for attaching water droplets to fine particles in the carbonation treatment of the present embodiment will be described. Specific methods include, for example, the following methods.

(1) Spraying with atomization nozzle First, a method of spraying water droplets using an atomization nozzle can be mentioned. As this atomization nozzle, for example, a commercially available two-fluid atomization nozzle can be used. The range of the particle size of water droplets sprayed by this two-fluid atomizing nozzle is about φ15 to 50 μm. Further, as the working fluid (spraying liquid) of the atomizing nozzle, water as a main component and a volatile liquid with a small surface tension (for example, ethanol) may be appropriately mixed as a surfactant. Mixing the surfactant in this way makes it easier to obtain droplets with a smaller diameter.

In addition, as described above, the spraying method using the atomization nozzle may be performed by spraying on the fine particles that have been previously left in the CO ₂ incubator before the carbonation treatment. More specifically, the spraying of water droplets by the atomization nozzle is performed by placing the substrate 1 horizontally in the container 11 of the incubator 10 and then using the atomization nozzle in parallel with the substrate 1 (horizontal direction) to inject the water droplets into the incubator 10. After spraying in, the incubator 10 may be sealed to perform carbonation. This is because the water droplets have a relatively large particle size, so that the water droplets can be easily maintained for a long time. The spray flow rate from the atomization nozzle at this time is preferably about 10 mL / min to 50 mL / min. If the spray flow rate is less than 10 mL / min, it takes a long time to spray the water droplets, so that the water droplets may dry and evaporate during the spraying. On the other hand, if the spray flow rate is higher than 50 mL / min, there is a possibility that the fine particles of the sample are blown away depending on the amount of the gas that is the power source of the water droplet injection.

(2) Spraying with an ultrasonic particle generator Secondly, there is a method of spraying water droplets using an ultrasonic particle generator. Here, a water droplet spraying method using an ultrasonic particle generator (ultrasonic sprayer) will be described with reference to FIG. FIG. 5 is an explanatory diagram showing an example of a device configuration in which an ultrasonic sprayer is attached to the CO ₂ incubator used for the carbonation treatment of the present embodiment.

  As shown in FIG. 5, an ultrasonic sprayer 41 is attached to the container 11 of the incubator 10, and fine water droplets (φ10 μm or less) are sprayed from the ultrasonic sprayer 41 into the container 11. As the ultrasonic sprayer 41, for example, a commercially available nebulizer or the like can be used. The spraying method using the ultrasonic sprayer 41 is provided with a through hole in the side wall of the container 11 of the incubator 10, and a conduit 42 of the ultrasonic sprayer 41 such as a nebulizer is connected to the through hole. The generated water droplets are caused to flow into the container 11. At this time, intake is performed at the end (inlet end) opposite to the end (outlet end) of the conduit 42 where water droplets are sprayed. Water droplets are sprayed from the part. Further, the amount of water droplet sprayed by the ultrasonic sprayer 41 is controlled by a spray control device 43 connected to the ultrasonic sprayer 41.

  In addition, as described above, in the spraying by the ultrasonic sprayer 41, very fine (φ10 μm or less) water droplets are sprayed. Therefore, the proportion of water droplets lost by evaporation of the sprayed water droplets is determined by the atomization nozzle. Higher than when used. Therefore, when the ultrasonic sprayer 41 is used, it is preferable to spray during the carbonation treatment because it is necessary to replenish water droplets appropriately during the carbonation treatment.

  Furthermore, the spray flow rate from the ultrasonic sprayer 41 is preferably about 1 mL / min to 5 mL / min. If the spray flow rate is less than 1 mL / min, it takes a long time to spray the water droplets, so that the water droplets may dry and evaporate during the spraying, and the effect of promoting the carbonation reaction is small. On the other hand, if the spray flow rate is higher than 5 mL / min, the amount of dew condensation of water vapor cannot be ignored, and there is a possibility of adverse effects such as elution of water-soluble components into liquid water condensed from slag.

(3) Method of Cooling Substrate Thirdly, there is a method of attaching fine water droplets to sample fine particles by cooling the substrate on which the sample is placed and allowing water vapor to condense on the fine particles.

  Here, with reference to FIG. 6, a method of adhering water droplets to sample fine particles by cooling the substrate will be described. FIG. 6 is an explanatory diagram showing an example of the configuration of an apparatus for cooling the prayer used for the carbonation treatment of the present embodiment.

  As shown in FIG. 6, a cooling device 51 is disposed between the substrate 1 and the shelf 22 so as to cool the substrate 1 on which the sample particulates P are placed from below. A commercially available Peltier element can be used as the cooling device 51. Further, the Peltier element itself may be used as the substrate 1. Further, the temperature of the Peltier element as the substrate 1 or the cooling device 51 is measured by a thermometer (thermocouple) 52. The lead wires and thermocouples of these Peltier elements are provided with through holes in the side wall of the container 11 of the incubator 10, drawn out from the through holes, and connected to the cooling control device 53. A commercially available temperature control device such as a thermostat can be used as the cooling control device 53, and the cooling control device 53 controls the cooling temperature of the cooling device 51 based on the temperature measurement result by the thermometer 52.

By cooling the substrate 1 in this way, the sample fine particles P are also cooled. At this time, since the inside of the incubator 10 is maintained at the saturated vapor pressure, the water vapor is condensed on the fine particles P and fine water droplets are generated. If the condensation of the water vapor is continued for a long time, the condensed water droplets are coarsened and combined with each other, and adverse effects such as elution of the water-soluble component from the slag appear. Therefore, the cooling is completed in a short time. Regarding the cooling time, for example, by inserting an endoscope with a seal inside the CO ₂ incubator 11, and continuously observing the surface state of the particulate P during cooling using this endoscope or the like, What is necessary is just to set suitably, such as calculating | requiring the time of dew condensation having occurred on the surface of most fine particles P, and setting this to the optimal cooling time (for example, 10 minutes). In addition, the water droplet once produced | generated can be maintained for a long time in the environment of saturated vapor pressure.

  Further, the cooling device 51 may be cooled using a water-cooled tube instead of a Peltier element. In this case, the water-cooled tube is brought into contact with the lower part of the substrate 1 on which the sample fine particles P are placed. The water-cooled tube may be provided with a through hole in the side wall of the container 11 of the incubator 10, and the cooling temperature may be controlled by a heater or a cooler installed outside the incubator 10.

  However, the method of maintaining fine water droplets on the fine particles is not limited to the method described above. For example, if the sample particulates are placed in an open atmosphere on a day with a humidity of 100%, and the temperature of the sample particulates and water droplets is controlled to be the same as the ambient air temperature by using a cooling device such as a heater or a Peltier element, Fine water droplets can be maintained on the surface of the fine particles for a long time.

(Drying of fine particles after carbonation)
Next, the sample of the fine particle mixture after the carbonation treatment in step S109 is left in the incubator 10, and water droplets attached to the surface of the fine particles are dried (S111). At this time, since the water droplets are fine particles, the drying time is short (for example, about 60 minutes).

(Magnetic separation method)
Next, although not shown in the figure, magnetized fine particles that can be magnetized by applying a magnetic force and non-magnetized by applying a magnetic force to the fine particle mixture after the carbonation treatment in step S109 using a magnet. It may be separated into fine particles. As the magnet used at this time, it is preferable to use a magnet having such a strong magnetic force that iron dust or steelmaking slag dust is magnetized and coal dust or blast furnace slag dust is not magnetized. Specifically, it is preferable that the magnetic flux density of the magnet when the magnetic force is applied at the time of this magnetic separation is 0.1 T or more and 0.4 T or less at least on the surface of the fine particles. Here, the magnetization rate in the present invention means that a magnet having a substantially constant and uniform magnetic flux density on the attracting surface is brought into contact with the sample particle group, and the magnet is attracted to the magnet (magnetized particles) and not attracted. The ratio of the total amount of magnetized particles to the total amount of sample particles before separation when separated into (non-magnetized particles). Here, “total amount” means the total amount of mass when defined by mass ratio, and means the total amount of volume when defined by volume ratio.

  As a specific example of the magnet that can realize the above-mentioned preferable magnetic flux density range, for example, there is an electromagnet that can realize the magnetic flux density in the range of 0.1T to 0.4T. As the permanent magnet, a neodymium magnet, a samarium cobalt magnet, or the like having a magnetic force with a magnetic flux density in the range of 0.1 T to 0.4 T can be used. A ferrite magnet, which is a typical permanent magnet, has a low magnetic force, and is not suitable as a magnet used for magnetic separation in this embodiment.

  Further, when the magnet is brought into contact with the fine particle mixture, the tip of the magnet and the fine particle mixture may be brought into direct contact, and a separation plate is disposed between the magnet and the fine particle mixture, and the magnet is interposed via the separation plate. And the fine particle mixture may be brought into contact with each other.

The magnet only needs to have a flat shape at the tip (the side in contact with the fine particle mixture). As the magnet, for example, a cylinder or a prism can be used. Moreover, in order to ensure the contact with the particles of the fine particle mixture dispersed on the flat substrate and the uniformity of the magnetic force applied to each particle, the cross-sectional area of the tip of the magnet should be 0.1 cm ² or more. Is preferred. Also, when using a thin magnet with a small cross-sectional area at the tip as the magnet, the gradient of the magnetic flux density in the horizontal plane decreases as the distance from the tip of the magnet decreases, and the magnetic force becomes uniform. A spacer may be provided to prevent the fine particle mixture from approaching the tip of the magnet more than necessary. The material of such a spacer is not particularly limited as long as it is non-magnetic, and for example, a plastic plate (synthetic resin having elasticity such as rubber or vinyl chloride) or the like can be used. The shape of the spacer is not particularly limited, but a substantially ring shape can be used. Further, the material of the separation plate is not particularly limited as long as it is non-magnetic, but as described later, when the separation plate is placed on a sample of magnetic particles, by using a transparent material, It is preferable because the particle sample can be imaged through the placed separation plate. As such a transparent material, for example, a transparent acrylic material or the like can be used.

  As a specific magnetic separation method, first, a flat surface at the tip of a magnet is placed on a substrate on a fine particle mixture (consisting of magnetized particles and non-magnetized particles) dispersed on a flat first substrate. In a parallel state, the tip of the magnet is brought into contact directly or between the magnet and the fine particle mixture via a separation plate (may be shared with a spacer). The contact time between the magnet and the fine particle mixture at this time may be, for example, 1 second or longer.

  Thereafter, the magnet is pulled up (when a separation plate is used, the separation plate is pulled up as it is in contact with the magnet). At this time, the fine particle mixture remaining on the first substrate is a sample of non-magnetic particles. Further, the magnet on which the fine particle mixture is adsorbed is lowered on a second substrate different from the first substrate and brought into contact with the second substrate.

  Further, the magnet is separated from the fine particle mixture or the separation plate with the fine particle mixture attached to the lower surface. Specifically, when the magnet is an electromagnet, the current flowing through the electromagnet is turned off (in a device with a demagnetizing function, the current is turned off after supplying the demagnetizing electricity), and the magnet is pulled up and magnetized. The particles that have been left are left on the second substrate. On the other hand, when the magnet is a permanent magnet such as a neodymium magnet, the separation plate is fixed on the second substrate, and only the magnet is pulled up to leave fine particles (magnetized) under the separation plate. . By doing so, the magnetized fine particles can be pressed from above by the gravity of the separation plate, and the magnetized particles can be separated from the permanent magnet. In order to fix the separation plate, the separation plate may be simply placed on the second substrate using the gravity of the separation plate. At this time, the fine particles remaining on the second substrate are samples of magnetized particles.

(Image of fine particle mixture after carbonation treatment and representative brightness measurement)
Next, all the fine particles in the fine particle mixture carbonized in step S109 are imaged (S113), and image processing is performed on the captured image to measure the representative brightness of each fine particle (S115: Particle image processing measurement). Since the fine particle imaging method and the representative brightness measurement method in steps S113 and S115 are the same as those in steps S105 and S107 described above, detailed description thereof is omitted.

(Slag particulate identification method)
Next, the fine particles whose representative brightness measured in step S115 is higher than the representative brightness measured in step S107 are identified as slag fine particles containing free lime on the surface (S117 to S119).

  As described above, the lightness is changed only by the slag fine particles containing free lime as a result of the carbonation treatment in step S109. Therefore, the fine particle mixture is imaged before and after the carbonation treatment (steps S107 and S115). Then, the representative brightness of each fine particle before and after the carbonation treatment is compared, and it is determined whether or not there is a particle whose representative brightness after the carbonation treatment is higher than the representative brightness before the carbonation treatment (S117). As a result, in the focused particle, if the representative brightness after carbonation treatment is higher than the representative brightness before carbonation treatment, the focused particle is identified as slag fine particles containing free lime on the surface. (S119). On the other hand, as a result of the determination in step S117, in the focused particle, if the representative brightness after the carbonation treatment is lower than the representative brightness before the carbonation treatment, the focused particle is identified as another fine particle. (S121). As described above, fine particles lightened (lightened) after carbonation can be identified as slag fine particles. According to the method for identifying slag fine particles according to the present embodiment, it is only necessary to compare the brightness difference between the fine particles before and after the carbonation treatment. Therefore, regardless of the actual lightness value of the fine particles after the carbonation treatment, Slag particulates can be identified.

  Here, in the method for identifying slag fine particles according to this embodiment, in order to compare the brightness difference between the same fine particles before and after the carbonation treatment, it is necessary to associate individual particles before and after the carbonation treatment. As a method for this association, first, the back surface of each fine particle is fixed to a substrate or the like in advance with a water-insoluble adhesive, and the relative position between the fine particles on the same substrate is fixed, so that different images ( The same fine particles can be associated in the image before the carbonation treatment and the image after the carbonation treatment. Secondly, specific fine particles are not associated with the carbonation treatment, and only the lightness distribution of the fine particles is compared before and after the carbonation treatment. As a comparison method in this case, for example, image processing measurement is performed on particle images before and after carbonation treatment, a histogram of representative brightness of each particle in each image is created, and the configuration of particles for each brightness classification in the histogram Find the rate. Furthermore, the difference in the composition ratio obtained by subtracting the composition ratio of the particles after the carbonation treatment from the composition ratio of the particles after the carbonation treatment is obtained. Assuming that the composition ratio difference obtained by counting only those whose composition ratio differences are positive corresponds to the composition ratio of the particles having increased brightness after the carbonation treatment, the slag particles in the sample of the fine particle mixture are macroscopic. It can be identified as a simple composition rate. The advantage of this second method is that it is easier to handle particles than the first method.

  However, the method for associating the fine particles and the method for identifying the slag fine particles are not limited to the first and second methods described above, and other general methods can be applied. As a method of associating the fine particles, for example, a method of associating a difference in brightness average value of each particle before and after the carbonation treatment with a composition ratio of the slag fine particles can be applied. According to this method, the composition ratio of fine particles in which the difference in brightness average value before and after the carbonation treatment is positive can be identified as the composition ratio of slag particles.

[Slag Fine Particle Identification Method According to Second Embodiment of the Present Invention]
Next, a method for identifying fine slag particles according to the second embodiment of the present invention will be described with reference to FIG. FIG. 7 is a flowchart showing an operation flow of the slag particulate identification method according to the second embodiment of the present invention.

  Unlike the slag particulate identification method according to the first embodiment described above, the slag particulate identification method according to the present embodiment performs imaging of the particulate mixture only after the carbonation treatment, and performs image processing measurement of the captured image. In this method, the obtained representative lightness is higher than a predetermined lightness threshold value and identified as slag fine particles. In the following description, the difference from the first embodiment will be mainly described.

  Since the definition of the fine particle mixture is the same as that of the first embodiment, detailed description thereof is omitted.

  In the method for identifying slag fine particles according to the present embodiment, first, as shown in FIG. 7, a fine particle mixture is collected. In addition, since the collection method of a fine particle mixture is the same as that of 1st Embodiment, detailed description is abbreviate | omitted.

  Here, as a sample of the fine particle mixture used in the slag fine particle identification method according to the present embodiment, it is premised that a sample that can be predicted in advance that the high brightness particles are slag containing free lime on the surface is used ( S201).

  As a first example of such a fine particle mixture, there is a sample of a fine particle mixture generated in a specific factory (for example, a steelmaking factory, etc.), particle types that can be generated in the factory are limited, and slag is included among them. Other than fine particles, there are those that can be predicted to be all low-brightness particle types (for example, iron oxide powder).

  Moreover, as a second example of the fine particle mixture, there is dust falling collected outside the steel plant by the blast furnace method. Dust falling from steelmaking plants by the blast furnace method is mainly classified into four types of dust, coal-based dust, iron-based dust, blast-furnace slag dust, and steelmaking slag dust. In general, blast furnace slag dust and steelmaking slag dust are white light particles (light colored particles), and coal dust and iron dust are black light particles (dark colored particles). . Furthermore, steelmaking slag dust and iron dust are particles that can be magnetized in a magnet having a predetermined magnetic flux density, while blast furnace slag dust and coal dust are particles that are not magnetized in a magnet having the magnetic flux density. is there. Therefore, the collected dustfall is separated into magnetized particles and non-magnetized particles by a magnet, and each of the separated magnetized particles and non-magnetized particles is separated using a low magnification optical microscope. Image processing is performed, and the brightness level of individual dust particles is identified to distinguish light and dark particles, thereby separating coal-based dust, iron-based dust, blast furnace slag dust, and steelmaking slag. There are four types of system dust. Specifically, coal-based dust is dark and non-magnetic, non-magnetic dark particles, iron-based dust is dark, magnetized, magnetic dark particles, and blast furnace slag dust is light and non-magnetic. Non-magnetized light-colored particles, steel-making slag dust (slag with advanced aging, or slag lightened by the above-mentioned carbonation treatment) is a light-colored and magnetized bright-colored particle, etc. Can be determined. In addition, as a specific method for identifying the process of particle brightness, a generally-used method of particle image processing measurement can be used. For this particle image processing measurement, for example, a particle image processing measurement function that is normally installed in commercially available image processing software such as “ImageProPlus” may be used.

(Processing samples for analysis)
Next, the sample for analysis (specific object) is processed. Specifically, the collected particulate mixture (for example, falling dust particles) is sprayed on the substrate (S203). The specific method at this time is the same as the analytical sample processing method (S103) in the first embodiment.

(Carbonation treatment)
Next, fine water droplets are brought into contact with the fine particles dispersed on the substrate in step S203 for 1 hour or longer (S205). Further, the specific processing method in step S205 is the same as the carbonation processing (S109) in the first embodiment.

(Drying of fine particles after carbonation)
Further, the sample of the fine particle mixture after the carbonation treatment in step S205 is left to stand in an incubator and dried (S207). The drying method at this time is the same as the drying process (S111) in the first embodiment.

(Magnetic separation method)
Next, although not shown, magnetized fine particles that can be magnetized by applying a magnetic force to the fine particle mixture after carbonation in step S205 using a magnet and non-magnetized It may be separated into fine particles. Details of the specific method and the magnets used at this time are also the same as in the case of the first embodiment.

(Imaging the collected fine particle mixture)
Next, all the fine particles in the fine particle mixture processed in step S205 are imaged, and a particle image which is an image of the fine particle mixture is generated (S209). This fine particle imaging method (particle image generating method) is the same as the imaging method (S105 and S111) in the first embodiment.

(Particle image processing measurement: representative brightness measurement)
Next, by performing image processing on the particle image of the particle mixture imaged in step S209, the representative brightness of each particle is measured (S211). The method of measuring the representative brightness of the fine particles at this time is the same as the method of measuring the representative brightness of the fine particles in the first embodiment.

(Slag particulate identification method)
Next, among the fine particles whose brightness has been measured in step S211, the fine particles having the brightness whose representative brightness measured in step S211 is equal to or greater than a predetermined brightness threshold are identified as slag fine particles containing free lime on the surface. (S213-S217).

  By the carbonation treatment in step S205, it is only the slag fine particles containing free lime that the lightness of the relatively dark steelmaking slag is insufficiently aged, so that the fine particle mixture is imaged after the carbonation treatment. (Step S205) Fine particles that have been lightened (lightened) after carbonation, and steel slag that is sufficiently aged and collected at the time of collection can be identified as slag fine particles.

  Specifically, it is determined whether or not the representative brightness of each fine particle after the carbonation treatment in step S205 is higher than a predetermined brightness threshold (S213). As a result, if there is a particle higher than the predetermined brightness threshold, the particle is identified as a slag fine particle containing free lime on the surface (S215). On the other hand, if there is a particle lower than the predetermined brightness threshold, the particle is identified as another type of particle (S217). As described above, according to the method for identifying slag fine particles according to the present embodiment, the representative brightness of the fine particles only needs to be measured after the carbonation treatment, so that the operation for identifying the slag fine particles becomes simple.

  Here, the following values can be used as the lightness threshold value. For example, a sample of only a steelmaking slag type that has been subjected to carbonation treatment is prepared in advance, and particle image processing measurement is performed on an image obtained by imaging the sample to obtain a distribution of representative brightness of individual particles. The lower limit of this distribution (for example, [average value of representative brightness of each particle] −n · [standard deviation of representative brightness of each particle], n: 1 to 2.5, etc.) may be adopted as the brightness threshold value. it can.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

  Next, the present invention will be described more specifically with reference to examples.

Example 1
In this example, as a sample of the fine particle mixture, dust falling from a steelmaking plant by a blast furnace method was used, and a sample of steelmaking slag 6 μg, blast furnace slag 1 μg, coal 1 μg, coke 1 μg, and iron ore 1 μg (total 10 μg) It was created.

<Creation of analysis sample>
The sample prepared as described above is scooped and spread on the first aluminum plate treated with white alumite and spread on the aluminum plate using a stainless steel spatula so that the particles do not overlap each other. It was. The expanded particle group was present in the range of about 15 mm in diameter.

<Imaging particles>
Next, a commercially available trinocular stereomicroscope (objective lens magnification: 0.5 times), a commercially available ring light source (white light) in a lens barrel, a commercially available monochrome digital camera (CCD 6 million pixels, pixel dimensions are 3 [mu] m square) was mounted on the camera mounting opening. Next, the samples prepared as described above were placed on the stage of the microscope, and the illumination conditions were the same, and the aperture and exposure of the camera were taken in order under the same conditions to obtain particle images.

  At this time, the magnification of the microscope was adjusted so that the actual size of the particle to be measured was imaged to the same size on the CCD element of the camera. In addition, the particles to be recognized with a microscope are particles with a size of φ10 μm or more because they are dust falling and the particles are coarse. In the present embodiment, the size of the particles corresponds to 9 pixels or more of the CCD.

<Image processing>
For the particle image obtained as described above, commercially available particle image processing software IMAGRPRO PLUS VER. 5 was used for particle image processing measurement. At this time, the measurement target was the center position of each particle, the circle equivalent diameter of each particle, and the average brightness of each particle (the average value of the brightness of each pixel existing in the pixel region recognized as a particle).

  Specifically, using a predetermined lightness threshold value T, a pixel region having a lightness less than the lightness threshold value T is specified as a region where particles exist, and each pixel existing in the pixel region is specified. Based on the position and brightness, the center position, average brightness, and circle equivalent diameter of each particle present in the particle image were calculated, and the calculation results were recorded.

<Carbonation treatment>
Next, carbonation treatment was performed on the sample particles after the image processing using a CO ₂ incubator. Here, Yamato Scientific IT400 was used as the CO ₂ incubator. Further, a shelf board was provided in the incubator, and one substrate was placed on the shelf board. Furthermore, a stainless steel water tank of 300 mm square and 70 mm thickness was installed in the incubator, and a 50 W ceramic heater with a temperature sensor was put into the water tank as a water tank heater. The power supply line and signal line of this water tank heater were pulled out from the wall through-hole installed in the IT400 and connected to an external temperature control device for temperature control.

Further, as the substrate, an aluminum plate having a thickness of 30 × 30 × 2 mm was used, and a fine particle mixture as a sample was sprayed on the substrate. As a method of spraying water droplets, water (carbonated water) previously bubbled with carbon dioxide gas is sprayed into a CO ₂ incubator using a two-fluid atomization nozzle (product name “FOGMASTER”) (total 30 mL, sprayed for 60 seconds) The estimated average particle diameter of water droplets was 30 μm).

In addition, the operating conditions of the CO ₂ incubator include carbonation treatment with a set temperature of the incubator of 26 ° C., a set concentration of CO ₂ of 15% by volume, a set temperature of the water temperature in the water tank of 35 ° C., and an operating time of 3 hours. went.

  Next, a commercially available cylindrical electromagnet having a diameter of 10 mm is installed so that the central axis is in the vertical direction, and is supplied to the electromagnet so that the average magnetic flux density at the front end surface (lower end surface) of the magnet is 0.3T. The current was adjusted. In this state, the operator held the electromagnet by hand and lowered it vertically from above the particles dispersed on the aluminum substrate to bring the electromagnet into contact with the particles. After standing still in this state for 1 second, the electromagnet is lifted upward, the magnetized particles are moved together with the electromagnet, and the electromagnet is vertically aligned from above on a second aluminum plate treated with white anodized. Was lowered to place the electromagnet on the second aluminum plate. Next, after applying a degaussing current to the electromagnet, the supply of current to the electromagnet was stopped, and the electromagnet was lifted upward and separated from the second aluminum plate.

  The dimensions of the first aluminum plate and the second aluminum plate used were 30 mm × 30 mm in size and 3 mm in thickness. Moreover, as a demagnetizing method of the electromagnet, a commercially available electromagnet demagnetization controller was used.

  As a result of the above operation, the particles remaining on the first aluminum plate were used as non-magnetic particles, and the particles remaining on the second aluminum plate were used as magnetic particles.

  Furthermore, for each of the non-magnetized particles and the magnetized particles, the particles are imaged in the same manner as before the carbonation treatment, and image processing is performed on the captured images to obtain the representative brightness of each particle. It was measured.

<Result>
Next, create a histogram of the representative brightness of each particle in the particle image before and after the carbonation treatment, determine the composition ratio of the particles for each brightness category in the histogram, and after the carbonation treatment from the composition ratio of the particles after the carbonation treatment The difference in the composition ratio obtained by subtracting the composition ratio of the particles was determined. The composition ratio difference obtained by counting only those obtained by making the composition ratio difference positive was identified as the composition ratio of the steelmaking slag particles in the sample of the fine particle mixture. In addition, as the composition ratio of the particles, the mass composition ratio calculated by correcting the volume composition ratio with the density was adopted.

  As a result, the composition ratio of the particles is steelmaking slag: 61%, blast furnace slag: 8%, coal + coke: 21%, iron ore: 10%, and the composition ratio of the sample mixed in advance at a known mixing ratio is good I was able to reproduce it. Therefore, it was found that the method for identifying slag fine particles according to the present invention is an effective method for identifying particle types.

(Example 2)
This example was performed in the same manner as in Example 1 except that the representative brightness of particles by imaging and image processing of particles was measured only once after the carbonation treatment. However, in the present example, as a method for identifying steelmaking slag particles, unlike Example 1, those having a representative brightness obtained by image processing measurement higher than a predetermined brightness threshold were identified as slag fine particles. In addition, as a threshold value for brightness determination at this time, a sample of steel slag particles treated in advance with an aqueous ammonium sulfate solution was subjected to image processing to measure the brightness, and the lowest brightness value including most particles was used. .

  As a result, the composition ratio of the particles is steelmaking slag: 59%, blast furnace slag: 9%, coal + coke: 18%, iron ore: 14%, and the composition ratio of the sample mixed in advance at a known mixing ratio is good I was able to reproduce it. Therefore, it was found that the method for identifying slag fine particles according to the present invention is an effective method for identifying particle types.

1 substrate 10 CO ₂ incubator 11 container 12 heater 13 CO ₂ gas cylinder 14 CO ₂ gas on-off valve 15 thermometer 16 CO ₂ concentration meter 17 the control unit 21 the water tank 22 shelf 31 aquarium heater 32 temperature gauge 33 temperature controller 41 ultrasonic spray Machine 42 Conduit 43 Spray control device 51 Cooling device 52 Thermometer 53 Cooling control device P Fine particles W Water

Claims (14)

A method for identifying slag fine particles for identifying the slag fine particles from a fine particle mixture consisting of slag fine particles containing free lime on the surface and fine particles of a type different from the slag fine particles,
A first brightness measurement step of measuring the representative brightness of each fine particle by performing image processing on an image obtained by imaging all the fine particles in the fine particle mixture;
Carbonic acid in which at least one water droplet is brought into contact with each of all fine particles in the fine particle mixture placed in a normal temperature gas containing carbon dioxide gas having a concentration of 1 mol% or more and water vapor having a saturated water vapor amount for 1 hour or more. Chemical treatment process,
A drying step of drying the fine particles after the carbonation treatment step;
A second brightness measurement step of measuring the representative brightness of each fine particle by performing image processing on an image obtained by imaging all the fine particles in the fine particle mixture after the drying step;
Fine particles whose representative brightness measured in the second brightness measurement step is higher than the representative brightness measured in the first brightness measurement step are identified as slag fine particles containing free lime on the surface. An identification process;
A method for identifying fine slag particles, comprising: A method for identifying slag fine particles for identifying the slag fine particles from a fine particle mixture consisting of slag fine particles containing free lime on the surface and fine particles of a type different from the slag fine particles,
Carbonic acid in which at least one water droplet is brought into contact with each of all fine particles in the fine particle mixture placed in a normal temperature gas containing carbon dioxide gas having a concentration of 1 mol% or more and water vapor having a saturated water vapor amount for 1 hour or more. Chemical treatment process,
A drying step of drying the fine particles after the carbonation treatment step;
A brightness measurement step of measuring the representative brightness of each fine particle by performing image processing on an image obtained by imaging all the fine particles in the fine particle mixture after the drying step;
Among the representative lightness values measured in the lightness measurement step, an identification step for identifying fine particles having a lightness of a predetermined value or more as slag fine particles containing free lime on the surface;
A method for identifying fine slag particles, comprising:   The slag fine particle identification method according to claim 1 or 2, wherein the slag fine particles containing free lime on the surface is steelmaking slag.   The slag particulate identification method according to any one of claims 1 to 3, wherein the particulate mixture is made of dust falling from a steelmaking plant by a blast furnace method. In the carbonation treatment step, the fine particles are allowed to stand in a CO ₂ incubator maintained in a room temperature gas atmosphere containing carbon dioxide gas having a concentration of 1 mol% or more and water vapor having a saturated water vapor amount. The identification method of the slag microparticles | fine-particles of any one of Claims 1-4. A water tank is disposed in the CO ₂ incubator, and the set temperature of the heater installed in the water tank is controlled to be maintained at a temperature higher than the set temperature of the atmosphere in the CO ₂ incubator, The method for identifying slag fine particles according to claim 5. In the carbonation process, the CO ₂ incubator, the substrate mounted with the respective minute particles are arranged horizontally, through the open portion of the CO ₂ incubator, with atomizing nozzles to the substrate and the horizontal water droplets after spraying the CO ₂ incubator, and which comprises carrying out the carbonation process to seal the CO ₂ incubator, the identification method of the slag particles according to claim 5 or 6. In the carbonation process, during implementation of the carbonation process, through the open portion of the CO ₂ incubator, spraying water droplets using an ultrasonic sprayer attached to the CO ₂ incubator in the CO ₂ incubator The method for identifying fine slag particles according to claim 5 or 6, wherein: A substrate on which each of the fine particles is placed is placed in the CO ₂ incubator, and by cooling the substrate, water vapor in the CO ₂ incubator is condensed on each of the fine particles. The method for identifying fine slag particles according to claim 5 or 6, wherein: A carbonation treatment apparatus for use in the method for identifying slag fine particles according to any one of claims 1 to 9,
A CO ₂ incubator maintained in a room temperature gas atmosphere containing carbon dioxide gas having a concentration of 1 mol% or more and water vapor with a saturated water vapor amount;
A water tank installed in the CO ₂ incubator;
A substrate that is installed above the water tank and on which a fine particle mixture composed of slag fine particles containing free lime on the surface and fine particles of a type different from the slag fine particles is mounted;
A carbonation treatment apparatus comprising: A heater installed in the water tank;
A control device for controlling the set temperature of the heater to be higher than the set temperature of the atmosphere in the CO ₂ incubator;
The carbonation processing apparatus according to claim 10, further comprising: Further comprising an atomizing nozzle attached to the CO ₂ incubator;
The CO ₂ incubator is sealable;
The substrate is disposed horizontally in the CO ₂ incubator,
The atomizing nozzle, through the open portion of the CO ₂ incubator, characterized by spraying water droplets to the substrate and the horizontal direction to the CO ₂ incubator, carbonation apparatus according to claim 10 or 11. Attached to the CO ₂ incubator, through the open portion of the CO ₂ incubator, and further comprising an ultrasonic sprayer for spraying water droplets to the CO ₂ incubator, carbonation of claim 10 or 11 Processing equipment. 12. The carbonic acid according to claim 10, further comprising a cooling device installed at a lower portion of the substrate, which cools the substrate and causes water vapor in the CO ₂ incubator to condense on the fine particles. Processing equipment.

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