JP2009074158A - Lime powder coated with iron-containing layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lime power excellent in wettability to molten metal, contributing to the effective utilization in a field utilizing the wettability. <P>SOLUTION: On the outer surface and the internal surface of slender hole of the lime, a solution of a complex or a complex salt containing iron component is impregnated and thereafter, a solvent is removed and, the surface-treated lime which has been subjected to the heat treatment according to the need shows the excellent wettability to the molten iron. Further, on the lime surface and the slender hole internal surface, an iron-complex or an iron-complex salt or an organic solvent and a mixed liquor of polyol, are impregnated and thereafter, the solvent is removed, and the surface treated lime adjusted with heat-treatment according to the need, shows excellent wettability to the molten iron. Furthermore, the surface treated lime by dripping and mixing the mixed solution of the iron-complex or the iron-complex salt and only the polyol on the lime powder, shows the improved wettability to the molten iron. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a quicklime powder having a modified outer surface and pore inner surface, which is used as a steelmaking or steelmaking application or as an additive for steel, and a method for producing and using the same.

  The main application of quicklime is in the field of steelmaking and refined steel, but quicklime used in each process is also being considered to be suitable for each process. In particular, the improvement of wettability between quicklime and molten metal has been energetically advanced because not only the purification efficiency but also the product characteristics can be changed. The coating treatment of calcium ferrite containing an iron component has been studied for a long time. Patent Document 1 discloses a method of calcining and preparing limestone coated with iron oxide dust, and Patent Document 2 discloses granulation of limestone and calcium ferrite. A method of firing a product to form a porous body is disclosed. Patent Document 3 reports a method for producing quick lime coated with calcium ferrite by blowing iron oxide into quick lime supplied to the inside of the firing furnace. Furthermore, Patent Document 4 describes a method of obtaining quick lime covered with calcium ferrite by firing and classifying limestone covered with iron ore with a rotary kiln.

When the surface of the quicklime powder granule is observed in detail, many characteristic pores exist in the vicinity of 0.2 μm. For example, the pore surface area is about 6 square meters per gram. Larger pores are simultaneously formed with a small amount. In order to modify these pores, the above-mentioned method cannot cope with it. One of the countermeasures is impregnation coating treatment, and a method of using a titanium compound to increase the digestion resistance of calcia refractories (Patent Document 5) has been reported, but the coating effect by an iron compound has not been studied.
Japanese Patent Publication No.39-25588 JP 2004-176097 A Japanese Patent Publication No.49-48369 JP-A-11-209817 JP-A-10-245284 Chem. Lett. 1993, p. 1611.

  Providing quick lime powder particles that have not only wettability and reactivity to molten metal, but also increased reaction rate, by coating the outer surface of the quick lime powder particles and the internal primary particles, This will lead to increased efficiency, reduced by-product slag, and the development of new lime-based additives, leading to effective utilization of lime resources. As a method of introducing the iron component into the pores of the quicklime powder that is a porous body, the present inventors dissolved the iron complex in a non-aqueous solvent, and the outer surface of the quicklime powder and the inside of the pores. It was confirmed that it could be introduced effectively. Therefore, it was necessary to clarify which compound and which additional treatment improved wettability with molten metal.

  In the iron making process and the refined steel process, various conditions ranging from an oxidizing atmosphere to a reducing atmosphere are imposed. By applying the impregnation reforming method, it is another problem to develop a method for preparing quick lime coated with metallic iron or a low-oxidation iron oxide, and a method for expressing the effect thereof.

  Applying the impregnation method described above, introducing a specific iron complex to the surface of the quicklime powder and the internal surface of the pores, and finding that the surface-treated quicklime has a remarkable wettability improvement effect The present invention has been completed. The iron compound that can be used in the present invention is a complex or a complex salt that can be used by dissolving in an organic solvent or a chelating agent-containing solvent. For example, an iron ammine complex, a cyano complex, an oxygen coordination complex, a dicyclopentadienyl complex, and the like. is there. These substitution analogs are also available. Among the iron complexes, non-electrolytic organic solvents such as tris (acetylacetonato) iron (III) (hereinafter abbreviated as Fe complex), tris (ethylacetoacetate) iron (III), and the like can be used particularly preferably. It is a β-diketone complex having a high solubility in water.

  As the organic solvent that can be used in the present invention, an organic solvent that can be easily removed from the porous granular quicklime using a general-purpose heating device, a vacuum heating device, a combustion device, or the like can be used. For example, alcohols such as methanol, ethanol and propanol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, esters such as ethyl acetate, butyl acetate and ethylene carbonate, ethers such as dioxane, diglyme and dibutyl ether, toluene and xylene, etc. Aromatic hydrocarbons, organic halides such as carbon tetrachloride and ethylene chloride, fluorine-based solvents, mixed solvents such as BTX mixtures and modified alcohols, fuel oils such as kerosene and light oil, and the like can be used. A mixture of these can also be used. It is important to select the solvent to be used appropriately depending on the solubility of the iron complex and the method of removing the solvent.

  As a method for reducing and producing fine metals on the outer surface and the inner surface of fine pores, the polyol reduction method using metal complexes is considered effective. Precious metals, light transition metals and their alloy particles are produced by the polyol reduction method. Reduction to metal (Non-Patent Document 1). However, in the case of an iron complex, ordinary polyol reduction only produces magnetite with a low degree of oxidation and cannot be reduced to metallic iron. In view of the fact that surface-treated quicklime is used at high temperature rather than using a stronger reducing agent, the present inventors have come up with a method for applying carbon reducing power at high temperature. Therefore, a surface modification method for the purpose of generating a layer containing iron oxide (wustite or magnetite) with low oxidation as a reaction precursor and carbon on the outer surface of quicklime and the inner surface of pores was examined.

  In the polyol addition system, the polyol itself often serves as a good solvent for the iron complex or iron complex salt. Therefore, the purpose of using a solvent other than this is mainly concentration adjustment and viscosity adjustment rather than dissolution of a complex or complex salt, and the use of a readily volatile solvent other than polyol is not necessarily an essential requirement. Examples of the polyol reducing agent that can be used in the present invention include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, trimethylene glycol, propylene glycol, 1,2-hexanediol, 1,2-octanediol, and 1,2-decanediol. , 1,2-dodecanediol, dipropylene glycol and the like can be preferably used. Furthermore, polyols containing heteroatoms such as nitrogen and sulfur can also be used. In addition, etherified derivatives of the above diols such as lauryl glycol hydroxypropyl ether (LPE) can also be suitably used.

  As for the coverage of the thin layer containing the iron component, a sufficient effect is exhibited if it is 5% with respect to the weight of quicklime, and an excessive coverage beyond this will cause an increase in the processing cost. If the coverage is too low, there is a concern that the treatment effect cannot be obtained sufficiently, but it is calculated from the radius of divalent iron ions (0.92 to 0.75 angstrom) and the ion radius of oxygen (1.26 angstrom). In view of the variation of the specific surface area of the quicklime to be treated, a coverage of 0.001% or more is considered necessary. The coating state of iron oxide and carbon is considered to vary depending on the heating atmosphere, heating temperature, decomposition temperature of the complex and reducing agent, and needs to be individually verified before implementation.

  As will be described in more detail below, for example, when agglomerate 15-15 mm massive raw apatite is immersed in ethanol (2.5 w / v%) in which the Fe complex is dissolved for 1 minute at room temperature and normal pressure, the ethanol solution becomes massive. It penetrates easily through the pores of quicklime to the inside of the mass (FIG. 1). It can be confirmed that the white portion at the center of the cross section in FIG. On the other hand, as will be described later, in the same immersion treatment with an ethanol suspension of Bengala (1.0 w / v%), only the outermost surface is coated with Bengala, and no Bengala can be detected from the inside (FIG. 2). Both situations were in stark contrast. The quick lime powder obtained by the former method has improved wettability to pig iron, and the solution to the above problem has been achieved.

  In addition, when a mixture of 0.4 g of Fe complex and 0.08 g of diethylene glycol (DEG) is put in a crucible, covered, and heated at 300 ° C. for 30 minutes, the formation of magnetite and graphite is determined from powder X-ray diffraction (PXRD) measurement. It was recognized (FIG. 1). Based on this finding, the present inventors prepared quick lime powder particles whose outer surface and inner surface of the pore were modified with an iron complex and a polyol. When a small piece of iron was placed on a disk-shaped molded body obtained by pressure-adjusting this powder and heated together, the weld wettability was remarkably improved.

The quick lime powder particles for surface treatment are obtained by pulverizing and classifying so-called soft calcined quick lime (calcium oxide) obtained by firing limestone produced in Okayama Prefecture in a rotary kiln having a furnace temperature of about 1050 ° C. The present invention can deal with quick lime prepared in another type of calcining furnace in another production area having different particle sizes by adjusting the immersion time and the like. Depending on the application, a lump with a diameter of several tens of millimeters is used, but it is clear that the present surface treatment method can be applied to these as well, and it is included in the granular material of the present specification. Note that CaO component in powdered quicklime used was 97.47%, the remaining components MgO: 1.07%, SrO: 0.16 %, SiO 2: 0.58%, Al 2 O 3: 0. It was 24%, P ₂ O ₅ : 0.11%, SO ₃ : 0.35%, K ₂ O: 0.02%. As is generally well known, this soft calcined lime powder is a porous body having an aggregate structure of ellipsoid-like primary particles having a size of about 2 μm and a large number of pores between them. . From the measurement of the pore distribution with a mercury porosimeter, a large pore diameter peak was observed near 160 nm.

  Ethanol (99.5%), polyol and Fe complex were purchased as reagents and used as they were without purification. The wettability between quicklime and pig iron is observed and evaluated with a high temperature wettability tester (ULVAC-RIKO, WET-1200 type). # 110-12) was used. Components other than iron of this material are: C: 4.18%, Si: 1.70%, Mn: 0.392%, P: 0.0902%, S: 0.0251%, other impurities: 0.0799 %Met. Hereinafter, the content of the present invention will be described with reference to specific examples, but this does not exclude the method of performing another iron complex in combination with another organic solvent from the scope of the present invention. Further, there are optimum processing methods depending on the particle size of quicklime, and some of them are shown in the following specific examples, but other treatment methods are not intended to be excluded. For example, spray drying is applied to ultrafine quicklime powder. Laws are more effective.

Preparation of quick lime coated with a thin layer containing an iron component As Preparation Example 1, 100 mL of 99.5% ethanol was placed in a 500 mL round bottom flask, and 5.0 g of Fe complex was added and dissolved. A suspension was prepared by adding 100 g of a particle size adjusted to 0.5 mm or less. This was transferred to a rotary evaporator and ethanol was distilled off to obtain a solid, which was then placed in a constant temperature dryer at 130 ° C. and dried. A slightly creamy quicklime powder was obtained. Next, a part of the dried product was taken into a magnetic crucible and baked in an electric furnace at 500 ° C. for 30 minutes. The CaO coverage by Fe ₂ O ₃ calculated from the addition rate of the Fe complex to quicklime (5.0% by weight) was 1.1% by weight.

  From the surface-treated quicklime obtained by PXRD analysis, peaks of calcium hydroxide and calcium carbonate were also observed. An iron element mapping analysis by an X-ray microanalyzer confirmed that the Fe element was uniformly distributed over the entire surface of the granular material (FIG. 3). As described above, this coincides with the result of the permeation state of the cross section shown in the lump treatment of massive quicklime (FIG. 1). That is, 15 to 20 mm of bulk quicklime is immersed in the Fe complex ethanol solution for 1 minute, then the quicklime is taken out, a cross section is taken out with a hammer, and the thickness of the light yellow colored layer is measured to measure the thickness of the Fe complex quicklime. Although the permeability to the inside was determined, the penetration distance is about 4 to 5 mm, and the Fe complex ethanol solution easily penetrates into the massive quicklime. In other words, it is reasonably presumed that the powder body adjusted to 0.5 mm or less is sufficiently covered up to the inside. In addition, the average primary particle diameter of the red bean used for the ethanol suspension of the red bean used for comparison is about 130 nm, which is slightly smaller than the average fine pore diameter of the quick lime (about 160 nm). Little penetration was observed (Figure 2).

The alcohol to be used often contains a small amount of moisture. In this case, quick lime is hydrolyzed and further carbonated to become modified quick lime containing slaked lime and calcium carbonate. It was found by thermal analysis that this modified quicklime dehydrated calcium hydroxide at 380 ° C to 470 ° C and decarboxylated calcium carbonate at 550 ° C to 750 ° C. These alcohol modifications had a minor effect on the wettability between hot metal and quicklime.

As Preparation Example 2, granular quicklime having a slightly larger particle diameter was treated with an Fe complex. The particle size distribution of the quicklime used was over 4 mm: 3.7%, 4 mm to 2 mm: 64.4%, 2 mm to 1 mm: 10.5%, less than 1 mm: 21.4%. 450 g of this granular material was placed in a stainless steel ball, and 500 mL of a solution of denatured alcohol (ethanol 90%, methanol 10%) containing 2.5% Fe complex was added. After soaking for 5 minutes, excess alcohol was removed by decantation, and the remaining quicklime was transferred to a vat and placed in a shelf dryer and dried under reduced pressure. Thereafter, a portion of the dried product was transferred to a magnetic crucible and baked for 30 minutes in an electric furnace set at 1050 ° C. From the PXRD analysis of this calcined product, formation of Ca ₂ Fe ₂ O ₅ was observed in addition to CaO (2K value of CuKα1 and peaks at 33.0 °, 33.2 ° and 46.6 ° in addition to CaO. Was recognized).

Comparison of wettability with hot metal 200 mg of the surface-treated quicklime obtained in Preparation Examples 1 and 2 of Example 1 were separately put into a tablet press, and a 14.7 kN force was applied to form a 10 mmΦ × 2 mm thick disk. About 15 mg of pig iron standard material (Japan Iron and Steel Federation, # 110-12) was placed on the molded body, and the pig iron and the molded body were placed on a sample support of a high temperature wettability tester. After replacing the inside of the furnace with argon, the temperature was raised from room temperature to 800 ° C. at a rate of 40 ° C. per minute. Thereafter, the temperature was raised from 800 ° C. to 1200 ° C. at a rate of 10 ° C. per minute, held at 1200 ° C. for 5 minutes and then released. After cooling, the state change of pig iron in each heating process was observed. As a result, the wettability between the molded body of Preparation Example 1 and pig iron was clearly improved (FIG. 4). Further, it was confirmed by EPMA analysis that a layer containing silicon was formed at the interface between the compact and pig iron. The same wetting test operation was performed using a quicklime molded body that was not surface-treated, but molten pig iron droplets were formed on the molded body, and the wettability was not good (Comparative Example 1, FIG. 5). ). Although the improvement of wettability with pig iron was also observed in the molded body of Preparation Example 2, it was not as remarkable as Preparation Example 1.

Preparation of quicklime covered with a thin layer containing an iron component As Preparation Example 3, 100 mL of ethanol with a purity of 99.5% was placed in a 500 mL round bottom flask, and 2.5 g of Fe complex and 1.0 g of DEG were added and dissolved. A suspension was prepared by adding 100 g of calcium oxide adjusted to a particle size of 0.5 mm or less with calcium oxide. This was transferred to a rotary evaporator and ethanol was distilled off to obtain a solid, which was then placed in a constant temperature dryer at 130 ° C. and dried. A slightly creamy calcium oxide powder was obtained. In addition, as Preparation Example 4, 3.0 g of Fe complex was dissolved in 100 mL of diethylene glycol, and 10 mL of this was dropped onto a calcium oxide pulverized product (1.0 kg) adjusted to a particle size of 1.5 mm to 0.1 mm. The surface-treated quicklime was prepared by mixing using a mixer and impregnation.

Comparison of wettability with molten iron Example 3 The surface-treated calcium oxide obtained in Preparation Example 3 was observed in the same manner as in Example 2 to observe changes in the wet state of pig iron. It was confirmed that the entire upper surface of the compact was covered with the Si component, and iron fine particles were diffused into the surface layer. From the SEM image in FIG. 7 (left figure), only one spherical iron fine particle is observed, but in the FeMA mapping figure of EPMA (right figure), there are many fine iron particles in the vicinity. Admitted. In addition, in the Example using the quick lime molded object (preparation example 1) which did not contain diethylene glycol and was surface-treated only with Fe complex, although adhesion was recognized by the upper part of a molded object (FIG. 4), shaping | molding was carried out. No significant iron component diffusion into the body was observed. In this case, the Si component was observed only in the vicinity of the adhesion of pig iron, and there was no wide spread on the upper surface of the molded body.

  Example 3 The surface-treated quicklime prepared in Preparation Example 4 was molded at 140 kN, and a standard pig iron was placed thereon and heated in an argon atmosphere in a high temperature wettability tester, and the state change was observed. A photomicrograph of the sample immediately after standing to cool is shown in FIG. It was recognized that the wettability between the quicklime molded body surface and pig iron was also significantly improved by the simple surface treatment method.

  The remarkable improvement in wettability by pig iron and the improvement in digestion resistance by moisture in the air indicate the availability of the surface-treated quick lime according to the present invention in the use of quick lime utilizing these characteristics.

It is a cross-sectional photograph of the massive apatite immersed for 1 minute in ethanol (2.5 w / v%) which melt | dissolved Fe complex. It is a cross-sectional photograph of the massive apatite immersed for 1 minute in the ethanol suspension (1.0 w / v%) of Bengala. Scanning electron micrographs (SEM) of the quicklime powder before and after the surface treatment (upper left) in Example 1 and the mapping of the Fe element at the center portion corresponding to the quicklime powder after the surface treatment (upper left) Pictures are shown on the right side of each. It is a photograph of what put pig iron powder on the compact of surface treatment quicklime, heated to 1200 ° C, and then allowed to cool (Example 2). It is the photograph of what put the pig iron powder on the quick-lime molded object which has not performed surface treatment, and was left to cool after heating to 1200 degreeC (comparative example 1). In a PXRD pattern of a fired mixture of an Fe complex and diethylene glycol, G represents graphite and M represents magnetite. (Example 4) which is an EPMA analysis photograph of what put pig iron powder on the compact of the quick lime surface-treated with the mixture of Fe complex and diethylene glycol, heated to 1200 degreeC, and left to cool. The left is an SEM photograph, and the right is a mapping diagram of Fe element. It is the photograph of what put pig iron powder on the compact of surface treatment quicklime, heated to 1200 ° C, and then left to cool (Example 4, Preparation Example 4).

Claims (6)

  The iron component-containing thin layer covering the outer surface and the pore inner surface of the quicklime powder is a layer containing an iron complex or complex salt, or a partially decomposed product thereof or a layer containing an oxide thereof. Quicklime powder granules.   A layer containing an iron component-containing thin layer covering the outer surface and the inner surface of fine pores of quicklime powder, a layer containing an iron complex or complex salt and a polyol, or a layer containing a partial decomposition product of iron complex or complex salt or a reduced product thereof The quicklime powder granular material characterized by being.   3. A quicklime powder granule, wherein the iron component-containing thin layer according to claim 1 or 2 is a layer containing an iron β-diketone complex as an iron complex.   4. The quicklime powder granule according to claim 1, wherein the iron component-containing thin layer according to claim 1 reacts at least partially with the quicklime surface, or at least partially reacts with the digested or carbonated quicklime surface.   The iron component-containing thin layer covering the outer surface and the pore inner surface of the quicklime powder is a layer containing an iron complex or complex salt, or a partially decomposed product thereof or a layer containing an oxide thereof. A method of using quicklime powder in contact with molten metal.   A layer containing an iron component-containing thin layer covering the outer surface and the inner surface of fine pores of quicklime powder, a layer containing an iron complex or complex salt and a polyol, or a layer containing a partial decomposition product of iron complex or complex salt or a reduced product thereof A method of using quick lime powder particles in contact with molten metal.