JP2007161519A - Civil engineering and building material and its producing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a civil engineering and building material composed of water-granulated blast furnace slag in which fluorine concentration to be eluted satisfies ≤0.8 mg/L based upon a soil environmental quality standard, and to provide its producing method. <P>SOLUTION: The civil engineering and building material is composed of the water-granulated blast furnace slag in which particles having <0.5 mm particle diameter defined by the screening with a 0.5 mm opening mesh are ≤5 mass%. The civil engineering and building material composed of the water-granulated blast furnace slag is directly produced from a molten blast furnace slag by water-granulating the molten slag produced in a blast furnace, and produced by water-granulating the molten blast furnace slag to obtain the water-granulated blast furnace slag and removing at least a part of the particles having <0.5 mm particle diameter. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to civil engineering and building materials and a method for producing the same, and more particularly, to civil engineering and building materials composed of blast furnace granulated slag having a dissolved fluorine concentration of 0.8 mg / L or less of the soil environment standard and a method for producing the same. Is.

  Blast furnace slag is used as a material for civil engineering and construction such as cement and concrete aggregates and admixtures, or roadbed materials and ground improvement materials. This blast furnace slag is generated as a by-product when iron ore is reduced with coke to produce hot metal in the blast furnace. The blast furnace slag discharged from the blast furnace together with the hot metal is cooled and solidified after being separated from the hot metal. Blast furnace slag is classified into blast furnace slow-cooled slag and blast furnace granulated slag, depending on the cooling method. Among these, granulated blast furnace slag is sprayed with cooling water on the molten blast furnace slag discharged from the blast furnace to disperse it into fine granules. A pulverization process was performed. The process of rapidly cooling molten slag, such as blast furnace slag, with water to make it finer is referred to as “water granulation process”.

  By the way, in recent years, regarding the use of steel slag as a material for civil engineering and construction, steel slag may contain fluorine, and thus environmental regulations tend to be strengthened. That is, following the establishment of the Environmental JIS: “Slag Chemical Elution Evaluation Test Method” in September 2003, the steel slag for roads was revised as a product JIS, and the amount of fluorine elution was reduced to 0 around the end of 2007. It is expected that a regulation value of .8 mg / L or less will be applied.

  In blast furnace slag, there has been no report that environmental problems have occurred through its use until now, but considering the stricter regulations in the future, the concentration of dissolved fluorine in blast furnace granulated slag used as civil engineering materials will be further increased. Reduction is desired. In the steel smelting and refining process, fluorine is used as a melting point depressant for CaO-based slag and does not require fluorine in blast furnace operation, but it contains dust and slag generated in the steelmaking process that contains fluorine. In many cases, it is recycled as a blast furnace raw material (for example, sintered ore), and the fluorine content of the blast furnace slag tends to increase.

  Various means have been studied so far for reducing the dissolved fluorine concentration of granulated blast furnace slag. For example, Patent Document 1 proposes a method in which a new layer is formed on the surface of the slag by mixing aged slag containing fluorine and gypsum, and the fluorine in the slag is fixed or insolubilized. . In Patent Document 2, the fluorine concentration of cooling water when producing granulated blast furnace slag is controlled to a predetermined value or less in accordance with the fluorine concentration in the slag, thereby managing the amount of fluorine eluted from the granulated blast furnace slag. A method has been proposed.

Patent Document 3 discloses a method of managing the suspended sludge concentration in circulating cooling water to a predetermined value or less when manufacturing blast furnace granulated slag, thereby managing the amount of fluorine eluted from the blast furnace granulated slag. Proposed. Patent Document 4 proposes a method in which CaO—SiO ₂ slag is aged in a heated steam atmosphere to fix or insolubilize fluorine in the slag.
JP 2004-123476 A JP 2001-26472 A JP 2004-359474 A JP 2003-293023 A

  However, each of the above methods has the following problems. That is, the method of Patent Document 1 requires a new additive substance for suppressing elution, and has a problem that costs increase. The methods of Patent Documents 2 and 3 have a problem that the fluorine concentration cannot be lowered after dewatering the granulated blast furnace slag. In the method of Patent Document 4, since only aging treatment is performed, elution of fluorine cannot be suppressed, and there is a problem that it is difficult to reliably achieve a regulation value of 0.8 mg / L or less.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a civil engineering and building material composed of blast furnace granulated slag whose elution fluorine concentration satisfies the soil environmental standard of 0.8 mg / L or less. At the same time, the manufacturing method is provided.

  The inventors of the present invention have intensively studied and studied to solve the above problems. As a result, it was found that the dissolved fluorine concentration was affected by the particle size of granulated blast furnace slag.

  In other words, blast furnace granulated slag obtained by water granulation treatment is collected, sieved to various particle sizes with a sieving machine without performing crushing treatment after drying, and the concentration of eluted fluorine from blast furnace granulated slag at that time As a result of the investigation by particle size, the amount of elution from fine particles was large, and the elution fluorine concentration from blast furnace granulated slag was greatly influenced by the amount of fluorine eluted from fine particles in blast furnace granulated slag. It was. In particular, it was found that particles having a particle size of less than 0.5 mm when pulverized granulated blast furnace slag was sieved with a sieving machine having an opening size of 0.5 mm increased the eluted fluorine concentration.

  And, when the granulated blast furnace slag is subjected to water granulation treatment, by suppressing the generation of particles having a particle size of less than 0.5 mm, the ratio of particles having a particle size of less than 0.5 mm is 5 mass% or less of the entire blast furnace granulated slag. Or, after obtaining granulated blast furnace slag, remove at least a part of the granulated blast furnace slag with a sieve having a mesh size of 0.5 mm to remove particles with a particle size of less than 0.5 mm. When the ratio of particles having a particle size of less than 0.5 mm is 5% by mass or less, the concentration of fluorine eluted from blast furnace granulated slag can be 0.8 mg / L or less of the soil environment standard. I got the knowledge.

  The present invention has been made based on the above knowledge, and the civil engineering and building material according to the first invention is a ratio of particles having a particle diameter of less than 0.5 mm defined by sieving with an opening size of 0.5 mm. Is made of blast furnace granulated slag having a content of 5% by mass or less.

  In the method for manufacturing a civil engineering and building material according to the second invention, the molten blast furnace slag generated in the blast furnace is cooled with water, and the ratio of particles having a particle diameter of less than 0.5 mm is 5% by mass or less. The blast furnace granulated slag is produced directly from a molten blast furnace slag.

  According to a third aspect of the present invention, there is provided a method for manufacturing a civil engineering and building material, in which a molten blast furnace slag generated in a blast furnace is cooled with water to obtain a granulated blast furnace slag, and then the granulated blast furnace slag has a particle size of 0. 0. At least a part of the particles having a particle size of less than 5 mm is removed, and the ratio of the particles having a particle size of less than 0.5 mm is adjusted to 5% by mass or less.

  In the method for manufacturing a civil engineering building material according to the fourth invention, in the third invention, after performing a cooling treatment with water to obtain a blast furnace granulated slag, at least a part of the granulated blast furnace slag has an opening size. It is characterized by removing particles having a particle size of less than 0.5 mm by sieving with a 0.5 mm sieving machine.

  The civil engineering and building material comprising the granulated blast furnace slag of the present invention has a ratio of particles with a large particle size of less than 0.5 mm with a large amount of eluted fluorine of 5% by mass or less. It becomes possible to stably achieve 0.8 mg / L or less. Moreover, this civil engineering and building material can be directly produced by granulating the molten blast furnace slag generated in the blast furnace, or by sieving from the granulated blast furnace slag obtained by the granulation process. Since it can be produced simply by removing particles having a particle size of less than 0.5 mm, it can be produced at a very low cost and in large quantities.

  The present invention will be specifically described below.

  The civil engineering and building material according to the present invention is composed of a glassy blast furnace granulated slag obtained by granulating a molten blast furnace slag flowing out of a blast furnace together with hot metal. Granulated blast furnace slag is manufactured by, for example, rapidly cooling a molten blast furnace slag by jetting, mixing and stirring it, or by pouring the molten blast furnace slag into a large amount of water and quenching it. However, the method for producing granulated blast furnace slag is not particularly limited, and if the molten blast furnace slag generated in the hot metal production process in the blast furnace is cooled with water to form glassy slag, what will happen? It may be a simple method. The molten blast furnace slag becomes vitreous by rapid cooling.

  Moreover, the blast furnace granulated slag used as the civil engineering and building material of the present invention needs to have a ratio of particles having a particle size of less than 0.5 mm of 5% by mass or less of the entire blast furnace granulated slag used as the civil engineering and building material. There is. In the present invention, particles having a particle size of less than 0.5 mm are defined as particles passing through a sieving machine having an opening size of 0.5 mm. Therefore, if the minor axis is less than 0.5 mm, spindle-shaped or needle-like particles having a major axis of 0.5 mm or more are also included in the particles having a particle diameter of less than 0.5 mm in the present invention.

  The reason for the large amount of fluorine eluted from blast furnace granulated slag particles having a particle size of less than 0.5 mm is that (1) the fluorine in the cooling water adhering to the slag surface becomes a fine powder of the drying residue when the slag is dried. (2) Since the fine powder has a surface area larger than that of the granular or massive body, the fluorine contained in the granulated blast furnace granulated slag having a particle diameter of less than 0.5 mm is easily eluted. A point is considered.

  There are the following two methods for reducing the ratio of particles having a particle diameter of less than 0.5 mm to 5% by mass or less. One method is to adjust the amount of cooling water supplied to the molten blast furnace slag in order to disperse the molten blast furnace slag into a fine granule when the molten blast furnace slag is subjected to water granulation. The granulated blast furnace slag is produced directly with a small proportion of particles having a particle size of less than 0.5 mm, that is, the proportion of particles having a particle size of less than 0.5 mm is 5% by mass or less of the entire produced blast furnace granulated slag. Is the method.

  Another method is to remove at least a part of the particles having a particle size of less than 0.5 mm so that the particles having a particle size of less than 0.5 mm are 5% by mass or less after producing the granulated blast furnace slag. It is a method to do. A method for removing particles having a particle diameter of less than 0.5 mm is not particularly limited, and for example, blast furnace granulated slag may be removed through a sieving device or the like in the air or in water. Alternatively, blast furnace granulated slag may be blown off using wind power, and particles having a particle size of less than 0.5 mm may be removed depending on the landing position.

  Thus, by setting the ratio of particles having a particle diameter of less than 0.5 mm to 5% by mass or less of the whole, a material for civil engineering and construction having an elution fluorine concentration of 0.8 mg / L or less of the soil environment standard is used as blast furnace water. It can be produced stably from crushed slag.

  In the present invention, the content of particles having a particle size of less than 0.5 mm is specified because of the large amount of eluted fluorine. However, as a civil engineering and building material, the viewpoint of maintaining the ability to exhibit hydraulic properties by alkali stimulation. Therefore, it is necessary not to remove particles having a particle diameter of 0.5 mm or more.

  Moreover, the reason for setting the ratio of particles having a particle size of less than 0.5 mm to 5% by mass or less is that the concentration of eluted fluorine from the whole granulated blast furnace slag is 0.8 mg / Although it is based on the fact that it was confirmed that it is L or less, in order to more stably make the eluted fluorine concentration 0.8 mg / L or less, the ratio of particles having a particle diameter of less than 0.5 mm is 3% by mass or less. It is preferable that The upper limit value of the particle size of the granulated blast furnace slag does not need to be specified in particular, but large particles cannot be obtained because of the water granulation treatment, and is about 10 mm at the maximum.

  Thus, the civil engineering and building material comprising the granulated blast furnace slag of the present invention has a ratio of particles having a large particle size of less than 0.5 mm with a large amount of eluted fluorine of 5% by mass or less. It is possible to stably achieve the environmental standard of 0.8 mg / L or less.

  Granulated blast furnace slag generated in the blast furnace is granulated to produce granulated blast furnace slag, and this granulated blast furnace slag is collected and used in a sieve with an aperture size of 0.5 mm. Sieving was performed to separate a portion having a particle size of less than 0.5 mm and a portion having a particle size of 0.5 mm or more, and the ratio of the portion having a particle size of less than 0.5 mm was determined. Moreover, the fluorine elution test was done in the state as manufactured.

  The elution method of fluorine was carried out by the tank leaching test method. The tank leaching test method is based on JISK0058-1: 2005. As shown in FIG. 1, a blast furnace granulated slag 1 as it is manufactured is sampled in a solvent 2 (deionized water) contained in a container 3. The concentration of the component that is immersed and eluted is measured. In the test method and procedure, the sample and the solvent are accommodated in the container 3 so that the ratio of the solvent to the collected sample is 1:10 (the solvent having a volume 10 times the dry mass of the sample). The stirring blade 4 was put in, and after stirring the solvent for 6 hours, the solvent was collected and the concentration of fluorine was measured. The collected solvent was filtered through a membrane filter having a pore diameter of 0.45 μm in order to measure the concentration. The concentration of eluted fluorine was measured by a lanthanum alizarin complexone spectrophotometric method described in JISK0102, 1998-34.1. The test results are shown in Table 1.

  As shown in Table 1, in samples No. 1, 2, and 3 in which the ratio of particles having a particle size of less than 0.5 mm is 5% by mass or less of the entire granulated blast furnace slag, the elution amount of fluorine is 0 based on the soil environment standard. .8 mg / L or less. On the other hand, in samples No. 4, 5, 6, 7, and 8 in which the ratio of particles having a particle size of less than 0.5 mm exceeded 5% by mass of the entire granulated blast furnace slag, the elution amount of fluorine was determined based on soil environmental standards. Of 0.8 mg / L or less could not be achieved. It was confirmed that the higher the ratio of particles having a particle diameter of less than 0.5 mm, the more the fluorine elution amount tends to increase.

  In Example 1, sample Nos. 4 to 8 having an elution fluorine concentration exceeding 0.8 mg / L were partially screened using a sieving machine having an opening size of 0.5 mm to obtain a particle size of 0. The sample from which the part less than 0.5 mm was removed and the part from which the particle diameter was less than 0.5 mm was mixed with the original sample before removal, and the mixed sample was subjected to a fluorine elution test.

  First, the mixed sample is sieved with a sieving machine having an opening size of 0.5 mm and separated into a part having a particle size of less than 0.5 mm and a part having a particle size of 0.5 mm or more. The ratio of parts was determined. Subsequently, the fluorine elution test was done using the mixed sample. The fluorine elution test was performed in the same manner as in Example 1. Table 2 shows the sample numbers used, the ratio of particles having a particle size of less than 0.5 mm, and the results of the fluorine elution test.

  As shown in Table 2, in samples 4 to 8 in which the amount of fluorine elution was not able to achieve the soil environment standard of 0.8 mg / L or less in the state of being manufactured as blast furnace granulated slag, the particle size was 0. By removing at least a part of particles less than 5 mm and setting the ratio of particles less than 0.5 mm to 5% by mass or less, the amount of fluorine eluted becomes 0.8 mg / L or less of the soil environment standard. It was found to be suitable as a material for civil engineering and construction.

It is the schematic which shows the elution method test method of a fluorine.

Explanation of symbols

1 Blast Furnace Granulated Slag 2 Solvent 3 Container 4 Stirring Blade

Claims (4)

  A civil engineering and building material comprising a granulated blast furnace slag in which a ratio of particles having a particle size of less than 0.5 mm defined by sieving with an opening size of 0.5 mm is 5% by mass or less.   The molten blast furnace slag generated in the blast furnace is cooled with water, and granulated blast furnace slag in which the ratio of particles having a particle size of less than 0.5 mm is 5 mass% or less is directly produced from the molten blast furnace slag. The manufacturing method of the material for civil engineering and building characterized by these.   The molten blast furnace slag generated in the blast furnace is cooled with water to form a granulated blast furnace slag, and then at least a part of particles having a particle size of less than 0.5 mm is removed from the blast furnace granulated slag to obtain a particle size of 0. A method for producing a material for civil engineering and construction comprising adjusting the ratio of particles less than 5 mm to 5% by mass or less.   After cooling with water to form blast furnace granulated slag, at least a part of the granulated blast furnace slag is sieved with a sieve having an opening size of 0.5 mm to obtain particles having a particle size of less than 0.5 mm. It removes, The manufacturing method of the material for civil engineering construction of Claim 3 characterized by the above-mentioned.

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