JP2011203119A - Method for discriminating slag fine particles - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily discriminate slag fine particles only by the brightness data of individual particles by adapting particle image processing measurement in a method for discriminating the slag fine particles containing free lime on the surfaces thereof from a fine particle mixture becoming a sample.SOLUTION: This method for discriminating the slag fine particles includes a first brightness measuring process for measuring the representative brightness of respective fine particles by applying image processing to an image obtained by imaging all of the fine particles in the fine particle mixture, a chemical treatment process for bringing the respective fine particles into contact with an ammonium sulfate solution, a second brightness measuring process for measuring the representative brightness of the respective fine particles by applying image processing to an image obtained by imaging all of the fine particles in the fine particle mixture after the chemical treatment process and a discrimination process for discriminating the fine particles, wherein the representative brightness measured in the second brightness measuring process becomes higher than the representative brightness measured in the first brightness measuring process, as the slag fine particles containing free lime on the surfaces thereof.

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.

  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 JP 2002-179442 A JP 2004-161580 A 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 selectively reacted only the free lime contained in the slag fine particles by bringing the fine particle mixture to be a sample into contact with the ammonium sulfate aqueous solution. Based on this finding, it is possible to lighten the surface brightness of only slag fine particles containing free lime on the surface, thereby distinguishing slag fine particles containing free lime on the surface from other types of fine particles. The present invention has been completed.

  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 chemical treatment step for bringing each of the fine particles into contact with an aqueous ammonium sulfate solution A second brightness measurement step of measuring a 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 chemical treatment step; and the second brightness Fine particles whose representative brightness measured in the measurement step is higher than the representative brightness measured in the first brightness measurement step are free lime on the surface. Identification method of the slag particles comprising an identification step of identifying a slag particles containing are provided.

  The slag fine particle identification method preferably further includes a washing step between the chemical treatment step and the second brightness measurement step, wherein the fine particles after the chemical treatment step are washed with water and then dried.

  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, A chemical treatment process in which all the fine particles in the fine particle mixture are brought into contact with an ammonium sulfate aqueous solution, and image processing is performed on an image obtained by imaging all the fine particles in the fine particle mixture after the chemical treatment step. A lightness measurement step for measuring lightness, and an identification step for identifying fine particles having a lightness of a predetermined value or more among representative lightness values measured in the lightness measurement step as slag fine particles containing free lime on the surface, A method for identifying containing slag particulates is provided.

  The slag fine particle identification method preferably further includes a washing step between the chemical treatment step and the brightness measurement step, wherein the fine particles after the chemical treatment step are washed with water and then dried.

  In the method for identifying slag fine particles, examples of the slag fine particles containing free lime on the surface include steelmaking slag.

  Further, the slag fine particles and the fine particle mixture are, for example, dust falling generated from an iron manufacturing plant by a blast furnace method.

  In the method for identifying slag fine particles, in the chemical treatment step, the fine particles may be brought into contact with the aqueous ammonium sulfate solution by dropping a droplet of a mixture of an aqueous ethanol solution and an aqueous ammonium sulfate solution onto the fine particles.

  According to the present invention, particle image processing measurement is applied to a minute amount of specimen particles, for example, less than 10 mg, by uniformizing the brightness of slag fine particles containing free lime, which varies in brightness with the progress of aging, by chemical treatment. In addition, it is possible to easily identify the slag fine particles only by the brightness information of the 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. 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.

[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 a few weeks, so secure a place to keep slag for a long time. In addition, there is a problem that a large area of slag storage is required.

(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, Patent Documents 6 and 7 include a carbonate or bicarbonate aqueous solution (for example, a sodium carbonate aqueous solution, a sodium bicarbonate aqueous solution, or an ammonium carbonate aqueous solution) as blast furnace granulated slag. A method of contacting is disclosed. In this method, calcium carbonate is generated on the surface and the inside of the slag to coat the surface of the granulated blast furnace slag. In this case, it is the Ca oxide in the slag that is not liberated and that mainly reacts with carbonates and bicarbonates.

  For example, Patent Document 8 discloses a method for producing granulated slag 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. 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 9 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.

(Examination of application of accelerated aging technology)
Therefore, the present inventor can apply the technique such as accelerated aging 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 sodium carbonate aqueous solution into contact with slag>
Sodium carbonate is ionized into sodium ions (Na ⁺ ) and carbonate ions (CO ₃ ²⁻ ) in an aqueous solution. Since this carbonate ion has an equilibrium of the following formula (1) that is remarkably biased to the left (because of its high proton acceptability), it is hydrolyzed as shown in the following formula (2) to hydrogen carbonate ions (HCO ₃ ⁻ ). And hydroxide ions (OH ⁻ ). Therefore, an aqueous solution of sodium carbonate shows strong basicity. Thus, in the aqueous solution of sodium carbonate, Na ⁺ , HCO ₃ ⁻ , OH ⁻ and a small amount of CO ₃ ²⁻ exist.
HCO ₃ ⁻ ← → H ⁺ + CO ₃ ²⁻ (1)
CO ₃ ²⁻ + H ₂ O → HCO ₃ ⁻ + OH ⁻ (2)

Therefore, even when the aqueous sodium carbonate solution is brought into contact with the slag containing free lime on the surface, the concentration of CO ₃ ²⁻ is remarkably low, so the rate of formation of calcium carbonate on the slag surface is remarkably low. The effect of lightening is low.

  In addition, even if the concentration of sodium carbonate is high and the amount of carbonate ions is large to some extent, the solubility of calcium carbonate in water is considerably larger than that of calcium sulfate, so that it is much larger than the slag fine particles used in the present invention. Since it is difficult to saturate calcium carbonate in water, it cannot be applied to lightening the slag surface in the present invention.

Similarly, in the case of using sodium sulfate instead of sodium carbonate, sulfate ions (SO ₄ ²⁻ ) are also hard bases. Therefore, even if sodium sulfate is brought into contact with steelmaking slag, calcium sulfate is generated on the surface of the slag. The speed is low and the effect of lightening the slag surface is low.

<2. Method of contacting dilute sulfuric acid with slag>
If dilute sulfuric acid of about 0.1% by mass or more is brought into contact with the steelmaking slag using this method, a calcium sulfate layer is surely rapidly formed 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. 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.

<3. Method of contacting carbon dioxide alone with slag>
Even if dry slag not containing moisture and carbon dioxide gas are brought into contact with each other using this method, a calcium carbonate layer does not form on the slag surface. The reason why steelmaking slag and the like can be aged by this method in the prior art is that the slag normally holds a certain amount of free water on the slag surface. As a form in which the slag retains a certain amount of free water, the slag itself is porous and contains moisture in the pores, or a large number of slag grains are stacked, and moisture is preliminarily placed between these slag grains. It is either retained by the effect of surface tension or viscosity. As in the present invention, when a small amount of slag fine particles are arranged so as not to contact each other so that the particles can be photographed, it is difficult to naturally retain moisture in the form of slag in the prior art. is there. In addition, since the total mass of carbonated water in contact with the prior art method is much larger than the total mass of the target fine particles, in the prior art, the carbonated water contains excess CO _2. In addition, it is difficult to predict in advance whether or not carbonated water contains excess CO ₂ with respect to an unknown specimen. Therefore, when carbonated water contains excess CO ₂ , Most of the free lime (dissolved as calcium hydroxide ions) eluted from the water reacts with excess CO _{2 in} carbonated water to produce calcium bicarbonate (highly water-soluble), resulting in solid calcium carbonate salt (difficult Water soluble) is not produced in carbonated water. Therefore, this method cannot form a calcium carbonate layer on the surface of the slag fine particles, and is not suitable as a means for lightening the surface of the slag.

<4. Method of immersing slag in carbonated water>
When this method is used, there is a possibility that calcium carbonate is generated on the slag surface. In fact, when a large amount of slag is used as in the prior art, calcium carbonate is generated on the slag surface. However, the generation rate of calcium carbonate on the slag surface is not generally fast, and it is necessary to keep the carbonated water and slag in contact for a long time of at least several hours. On the other hand, although the solubility of calcium carbonate in water is relatively small, it has a solubility of about 0.8% by mass. As in the prior art, if the mass of slag immersed in carbonated water is as large as that of carbonated water, the calcium carbonate in carbonated water will be saturated, so the calcium carbonate produced near the slag will adhere to the slag surface and form a layer. Can be formed. However, when a small amount of slag as the object of the present invention is simply immersed in a large amount of carbonated water, calcium carbonate generated on the slag surface by aging before sampling is eluted into the carbonated water. Depending on the slag fine particles, some of the slag fine particles are darkened (lower brightness). Therefore, it is not suitable as a means for uniformly lightening all the slag fine particles as a sample.

  In principle, it is possible to lighten all of the slag fine particles uniformly if carbonated water equivalent to the minute amount of fine particles as the object of the present invention can be uniformly contacted with all the particles. There are no such methods disclosed. For example, even if minute water droplets (for example, several tens of μm in diameter) are adhered to individual slag fine particles by spraying, such small water droplets easily evaporate. Can not. If the water brought into contact with the dispersed slag particles is to be retained for a long time, it is necessary to laminate the slag particles again as in Patent Document 9. However, in the present invention, since it is necessary to arrange a minute amount of slag fine particles so as not to contact each other so that the particles can be photographed, it is practically impossible to stack slag particles.

<5. Method for producing ammonium sulfate solid layer on slag surface by bringing ammonium sulfate water into contact with molten slag>
In the present invention, it is necessary to photograph particles obtained by the process of lightening the surface of the slag particles and perform particle image processing measurement. Therefore, unlike the present method, the particles cannot be melted. In addition, as described in Patent Document 8, the ammonium sulfate layer produced by this method is not chemically bonded to the surface of the slag grains and has high water solubility. Upon contact with unavoidable water, ammonium sulfate quickly dissolves into the water and the coating layer disappears. Therefore, this method is not suitable as a means for obtaining particles used for particle image processing measurement.

  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, it is possible to selectively generate a light-colored substance only on the surface of slag fine particles containing free lime on the surface by bringing the fine particle mixture containing slag fine particles containing free lime on the surface into contact with the ammonium sulfate aqueous solution. I found out.

  According to this method, a calcium sulfate layer is formed on the surface of the slag fine particles by bringing the aqueous ammonium sulfate solution into contact with the slag fine particles containing free lime on the surface. Since calcium sulfate is a light color close to white, not only can slag be identified as light (high lightness) fine particles, but also its solubility in water is relatively low, so calcium sulfate produced on the surface of slag is similar to calcium carbonate. It can function as a light solid coating layer for each slag fine particle. The reason for this will be described below.

In the present invention, an oxide (or hydroxide) such as Ca or Fe on the slag surface is brought into contact with ammonium ions in the aqueous solution by bringing a fine particle mixture containing slag fine particles containing free lime on the surface into contact with the aqueous ammonium sulfate solution. Hydrogen bonds with the hydrogen to form a concentrated ammonium layer on the slag surface. Since ammonium ions are acids that are harder than at least Ca ²⁺ and Na ⁺ (see, for example, Chemical Physics Letters 260 (1996) 236-242, “Solvation energies from the linear response function of H,” According to the above, it is easy to selectively bind to SO4 ²⁻ which is a hard base, and a dense SO4 ²⁻ layer is simultaneously formed on the surface of the slag fine particles through hydrogen bonds of ammonium ions. Ca ²⁺ ions present on the surface of the slag fine particles are a kind of hard acid. Therefore, if Ca ²⁺ and a dense SO 4 ²⁻ layer are present on the surface layer of the slag fine particles, some of them form CaSO ₄ to form slag fine particles. Deposit on the surface of the. This is the reason why the CaSO ₄ layer is formed on the surface of the slag fine particles in the present invention.

On the other hand, for example, when a fine particle mixture containing slag fine particles containing free lime on the surface is brought into contact with an aqueous sodium sulfate solution, Na ⁺ which is a kind of hard acid does not hydrogen bond with the surface of the slag fine particles. Therefore, it is impossible to form a thick SO4 ²⁻ layer on the surface of the slag fine particles. Therefore, even when Ca ²⁺ ions from the surface of the slag particles are released, forming a CaSO ₄ in the vicinity of the surface of the slag particles are rare, form CaSO ₄ in an aqueous solution sufficiently distant from the surface of the slag particles To do. In the system which is the subject of the present invention, since the amount of water is generally extremely large relative to the slag particles which are fine particles, the CaSO ₄ concentration in the aqueous solution located far from the slag particles is generally higher than the saturation concentration. The CaSO ₄ produced therein cannot be precipitated as a solid. This is the reason why CaSO ₄ does not deposit on the surface of the slag fine particles when an aqueous sodium sulfate solution is used.

  Based on the same principle, any ion that forms a hard acid and that forms a hydrogen bond with the material on the surface of the slag fine particles can be applied to the present invention. For example, various amines such as monomethylammonium ion can be applied instead of ammonium ion.

When dilute sulfuric acid is used, hydrogen is a hard acid and can form hydrogen bonds on the surface of the slag fine particles, so that CaSO ₄ can be formed on the surface of the slag fine particles. Since there is a defect that particles are dissolved, it cannot be applied to lightening the slag surface in the present invention.

  As described above, when the aqueous ammonium sulfate solution is brought into contact with the fine particles, a light-colored calcium sulfate layer can be formed on the surface of the fine particles only for the slag fine particles containing free lime on the surface. 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, chemical processing, 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 chemical treatment)
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.

(Chemical treatment)
Next, each fine particle imaged in step S105 and subjected to image processing in step S107 is brought into contact with an aqueous ammonium sulfate solution (S109). The reason for using the aqueous ammonium sulfate solution in this treatment is as described above.

  As a specific treatment method, for example, an aqueous ammonium sulfate solution having a concentration of 0.1% by mass to 10% by mass is mixed with an aqueous ethanol solution, and a droplet of a predetermined amount of the mixed solution is used as a sample of the fine particle mixture by using a dropper or the like. Dripping. The concentration of the aqueous ethanol solution at this time is preferably 0% by mass to 90% by mass. It is possible to add 0 mass% ethanol, that is, not adding ethanol when the sample of the fine particle mixture is as large as several g or more. On the other hand, it is necessary to increase the concentration of ethanol as the amount of the sample of the fine particle mixture decreases, but when the sample is about several tens of μg to several hundreds of μg, the surface tension of water is increased when the proportion of water is high. Because it is strong, the aqueous solution cannot come into surface contact with the fine particles. Therefore, the ethanol concentration is preferably 90% by mass or less. Considering the amount of a normal fine particle mixture sample, the concentration of ethanol is preferably about 50% by mass to 80% by mass.

  Moreover, it is preferable that the dropping amount of the droplet of the mixed aqueous solution of the ammonium sulfate aqueous solution and the ethanol aqueous solution is about 0.1 to 10 times the total mass of the fine particle mixture as a sample. When the dropping amount of the mixed aqueous solution is too small, the amount of calcium sulfate produced by the aqueous ammonium sulfate solution is small, and the effect of lightening the surface of the slag fine particles is low. On the other hand, when the dripping amount of the mixed aqueous solution is excessive, the generated calcium sulfate is eluted in water, and a coating layer on the surface of the light-colored calcium sulfate slag fine particles cannot be formed.

  After dropping the mixed aqueous solution, the fine particle mixture is allowed to stand for about 1 hour. When the standing time is too short, the amount of calcium sulfate produced by the aqueous ammonium sulfate solution is small, and the effect of lightening the surface of the slag fine particles is low. When the standing time is excessive, the components of the surface layer of other water-soluble particles (for example, blast furnace slag) may elute into water, and the slag fine particles may have low brightness. In the present invention, the slag containing free lime is obtained by utilizing the difference in the reaction rate of water between the free lime remaining on the slag surface (fast reaction) and the calcium oxide (slow reaction) fixed inside the slag. Can react independently.

(Cleaning and drying of fine particles after chemical treatment)
Next, the sample of the fine particle mixture after the treatment is washed by immersing the sample of the fine particle mixture after the treatment in Step S109 in water contained in a predetermined container and allowing to stand for about 10 minutes. Further, a sample of the fine particle mixture is taken out from the container and dried in the atmosphere (S111).

  The purpose of the cleaning in step S111 is that if the ammonium sulfate is dried in a state where it remains on the particle surface, the white ammonium sulfate film covers the particle surface on the surface of the other particles and deteriorates the visibility. The ammonium sulfate concentrated on the surface is dissolved in water and removed. Since ammonium sulfate has a very high solubility in water, it can be washed for a short time even in contact with a small amount of water. When the standing time in the cleaning process in step S111 is too short, ammonium sulfate remains on the particle surface, and thus visibility may be deteriorated. On the other hand, when the standing time is too long, components of the surface layer of other water-soluble particles (for example, blast furnace slag) may elute into water, and the slag fine particles may have low brightness.

(Magnetic separation method)
Next, although not shown, magnetized fine particles and non-magnetized fine particles that can be magnetized by applying a magnetic force to the fine particle mixture after the ammonium sulfate treatment in step S109 by applying a magnetic force using a magnet. And may be separated. 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 chemical treatment and representative brightness measurement)
Next, all the fine particles in the fine particle mixture processed 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 chemical treatment in step S109. Therefore, the fine particle mixture is imaged before and after the chemical treatment (steps S107 and S115). The representative brightness of each fine particle before and after the treatment is compared, and it is determined whether or not there is a particle whose representative brightness after the chemical treatment is higher than the representative brightness before the chemical treatment (S117). As a result, in the focused particle, when the representative brightness after chemical treatment is higher than the representative brightness before chemical treatment, the focused particle is identified as slag fine particles containing free lime on the surface ( S119). On the other hand, if the representative brightness after the chemical treatment is lower than the representative brightness before the chemical treatment in the focused particle as a result of the determination in step S117, the focused particle is identified as other fine particles ( S121). As described above, fine particles lightened (lightened) after chemical treatment 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 chemical treatment, so the slag can be extracted from the fine particle mixture regardless of the actual lightness value of the fine particles after the chemical treatment. Fine particles 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 chemical treatment, it is necessary to associate individual particles before and after the chemical 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 chemical treatment and the image after the chemical treatment). Second, specific fine particles are not associated by chemical treatment, and only the lightness distribution of fine particles is compared before and after chemical treatment. As a comparison method in this case, for example, image processing measurement is performed on particle images before and after chemical treatment, a histogram of representative brightness of each particle in each image is created, and the composition ratio of particles for each brightness classification in the histogram Ask for. Further, the difference in the composition ratio is obtained by subtracting the composition ratio of the particles after chemical treatment from the composition ratio of the particles after chemical treatment. Assuming that the composition ratio difference obtained by adding only the obtained composition ratio differences becomes positive corresponds to the composition ratio of the particles having increased brightness after chemical treatment, the macroscopic slag particles in the sample of the fine particle mixture It can be identified as a 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 for associating the fine particles, for example, a method of associating the difference in brightness average value of each particle before and after the chemical treatment with the 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 chemical treatment is positive can be identified as the composition ratio of slag particles containing free lime on the surface.

  In addition, this method can be used when the progress of aging is evaluated using a fine particle specimen of only steelmaking slag. That is, it can be considered that the higher the proportion of particles that become lighter after chemical treatment, the lower the progress of aging.

  Note that the brightness of the particles may be identified by photographing by immersing the camera lens in an aqueous solution containing the fine particle mixture. In this case, since there is no precipitation of ammonium sulfate at the time of photographing, it is not always necessary to wash and dry the fine particle mixture.

[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. 3 is a flowchart showing a flow of operations of the slag particulate identification method according to the second embodiment of the present invention.

  The slag particulate identification method according to the present embodiment is different from the slag particulate identification method according to the first embodiment described above, and the particulate mixture is imaged only after chemical processing and obtained by image processing measurement of the captured image. This is a method for discriminating a slag fine particle whose representative lightness is higher than a predetermined lightness threshold. 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. 3, the 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 into 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 and steelmaking slag dust (slag that has been aged or slag lightened by the above-mentioned chemical treatment) are discriminated as light-colored and magnetized light-colored particles. can do. 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.

(Chemical treatment)
Next, the fine particles dispersed on the substrate in step S203 are brought into contact with an aqueous ammonium sulfate solution (S205). The reason for using the aqueous ammonium sulfate solution in this treatment is as described above. The specific processing method in step S205 is the same as the chemical processing (S109) in the first embodiment.

(Cleaning and drying of fine particles after chemical treatment)
Next, the sample of the fine particle mixture after the treatment in step S205 is washed with water, and the washed sample is further dried in the atmosphere (S207). The cleaning and drying method and purpose at this time are the same as those of the cleaning and drying process (S111) in the first embodiment.

(Magnetic separation method)
Next, although not shown, magnetized fine particles and non-magnetized fine particles that can be magnetized by applying a magnetic force to the fine particle mixture after the ammonium sulfate treatment in step S205 by applying a magnetic force using a magnet. And may be separated. 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).

  Since the chemical treatment in step S205 is only slag fine particles containing free lime, the aging is insufficient and the lightness of the relatively dark steel-making slag is lightened, so the fine particle mixture is imaged after the chemical treatment (step S205), fine particles lightened (lightened) after chemical treatment, and light steelmaking slag that is sufficiently aged 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 chemical 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 chemical 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 chemical treatment is created 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 is used, and steelmaking slag 3 mg, blast furnace slag 0.5 mg, coal 0.5 mg, coke 0.5 mg, and iron ore 0.5 mg A sample (total 5 mg) was prepared.

<Creation of analysis sample>
Scrub 500 μg of the sample prepared as described above, spray it on the first aluminum plate treated with white alumite, and use a stainless steel spatula to prevent the particles from overlapping each other. Expanded. The expanded particle group was present in the range of about 10 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.

<Chemical treatment>
Next, a mixed solution of 20 μg of an aqueous ammonium sulfate solution having a concentration of 5% by mass and 80 μg of ethanol was dropped onto the particles of the sample after the image processing with a micropipette, and allowed to stand for 1 hour. Thereafter, the sample after chemical treatment was washed by being immersed in water for 10 minutes and allowed to stand, and then naturally dried in the atmosphere (in a desiccator) for 4 hours.

  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 chemical treatment, and the imaged image is processed to measure the representative brightness of each particle. did.

<Result>
Next, a histogram of the representative brightness of each particle in the particle images before and after the chemical treatment is created, and the composition rate of the particles is obtained for each brightness category in the histogram. From the composition rate of the particles after the chemical treatment, The difference in composition rate was calculated by reducing the composition rate. 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 the particles by imaging and image processing of the particles was performed only once after the chemical 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 steel composition slag: 56%, blast furnace slag: 9%, coal + coke: 20%, iron ore: 15%, 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.

(Comparative Example 1)
In this comparative example, the composition ratio of the sample particles was determined in the same manner as in Example 2 except that no chemical treatment was performed. 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 in Example 1 and the like.

  As a result, the composition ratio of the particles was steelmaking slag: 23%, blast furnace slag: 7%, coal + coke: 23%, and iron ore: 47%. From this result, in the method of Comparative Example 1, the composition ratio of the steelmaking slag was underestimated (magnetically dark steelmaking slag was mistakenly recognized as iron ore), and the method of Comparative Example 1 was It can be said that it is not an effective particle type identification method.

(Comparative Example 2)
In this comparative example, as an aqueous solution used for chemical treatment, an aqueous solution of sodium sulfate, an aqueous solution of magnesium sulfate, an aqueous solution of potassium sulfate, an aqueous solution of sodium carbonate, an aqueous solution of magnesium carbonate, an aqueous solution of potassium carbonate, an aqueous solution of sodium hydrogencarbonate, an aqueous solution of magnesium hydrogencarbonate, an aqueous solution of potassium hydrogencarbonate The composition ratio of the sample particles was determined in the same manner as in Example 1 except that an aqueous solution, saturated carbonated water, and dilute sulfuric acid (0.1% concentration) were used.

  As a result, when any aqueous solution was used, the particle composition ratio of the steelmaking slag was 18 to 27%, and the particle composition ratio of the iron ore was in the range of 45 to 59%. From this result, in the method of Comparative Example 2, the composition rate of the steelmaking slag was underestimated (the dark and dark steelmaking slag was misrecognized as iron ore), and the method of Comparative Example 2 was It can be said that it is not an effective particle type identification method.

(Comparative Example 3)
In this comparative example, the composition ratio of the sample particles was determined in the same manner as in Example 1 except that dilute sulfuric acid (1% concentration) was used as the aqueous solution used for the chemical treatment.

  As a result, almost all of the iron ore in the sample of the fine particle mixture disappeared, and the mass balance before and after the chemical treatment was not achieved. Moreover, a transparent non-volatile liquid was produced from the coal and could not be dried after chemical treatment. Therefore, since it was difficult to capture particle images, it was impossible to perform particle image processing measurement.

(Comparative Example 4)
In this comparative example, as a chemical treatment method, a sample of the fine particle mixture is immersed in 50 g of saturated carbonated water for 10 hours (saturated carbonated water is left in a 100% carbon dioxide atmosphere and the solubility of carbonate in water is The composition ratio of the sample particles was determined in the same manner as in Example 1 except that the sample was maintained to have a saturated solubility) and the treated sample was then dried.

As a result, the granulated blast furnace slag collapsed due to hydration, and the particle size distribution before and after chemical treatment was not maintained. Moreover, the composition rate of the particles was steelmaking slag: 12%, blast furnace slag: 3%, coal + coke: 32%, iron ore: 53%. From this result, in the method of Comparative Example 4, the composition rate of the steelmaking slag was underestimated (the magnetically dark steelmaking slag was misrecognized as iron ore), and the method of Comparative Example 1 was It can be said that it is not an effective particle type identification method.

Claims (7)

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;
A chemical treatment step of bringing each of the fine particles into contact with an aqueous ammonium sulfate solution;
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 chemical treatment 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:   2. The slag according to claim 1, further comprising a washing step of washing the fine particles after the chemical treatment step with water and drying between the chemical treatment step and the second brightness measurement step. Particle identification method. 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 chemical treatment step of bringing all the fine particles in the fine particle mixture into contact with an aqueous ammonium sulfate solution;
A lightness measurement step of measuring the representative lightness 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 chemical treatment 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 according to claim 3, further comprising a washing step of washing each fine particle after the chemical treatment step with water and drying between the chemical treatment step and the brightness measurement step. Method.   The slag particulate identification method according to any one of claims 1 to 4, wherein the slag particulates containing free lime on the surface are steelmaking slag.   The slag particulate identification method according to any one of claims 1 to 5, wherein the particulate mixture consists of falling dust generated from an iron manufacturing plant by a blast furnace method. 7. The chemical treatment step according to claim 1, wherein the fine particles are brought into contact with the aqueous ammonium sulfate solution by dropping a droplet of a mixture of an aqueous ethanol solution and an aqueous ammonium sulfate solution onto the fine particles. 2. The method for identifying slag fine particles according to item 1.

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