JP2013087011A - Steel slag hydration hardened body, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-quality steel slag hydration solidified body enabling short-time aging treatment, and generating no crack caused by expansion even when being used for a long period, and to provide a method for manufacturing the same.SOLUTION: A simple body of steel slag subjected to a steam aging treatment under a steam atmosphere with a pressure of 0.2-1.0 MPa and having a particle size of <5 mm, or a material obtained by adding optionally an admixture and an alkaline stimulus material to the total amount of a mixture comprising a 40-60 mass% mixture of the steel slag and blast furnace slag having a particle size of <5 mm as fine aggregate, 20-40 mass% steel slag subjected to an aging treatment under a steam atmosphere with a pressure of 0.2-1.0 MPa and having a particle size of ≥5 mm to <40 mm as coarse aggregate, and a 10-30 mass% solidification assistant, is input into a block having a prescribed size and cured, to be thereby molded and solidified. A short-time aging treatment becomes possible, and a high-quality steel slag hydration solidified body generating no crack caused by expansion even when being used for a long period can be obtained.

Description

  TECHNICAL FIELD The present invention relates to a steelmaking slag hydrated hardened body having a water immersion expansion rate mainly composed of steelmaking slag and a method for producing the steelmaking slag hydrated hardened body.

  First, steel slag generated at an ironworks will be described.

  In the process of producing steel, slag is generated as a by-product. This slag is roughly classified into blast furnace slag and steelmaking slag according to the steel production process.

  The blast furnace slag is classified into a granulated slag rapidly cooled with a large amount of water and a gradually cooled slow slag discharged from the blast furnace. Of these, granulated slag is effectively used as a raw material for cement. On the other hand, the slow-cooled slag formed into a solid lump by the latent hydraulic property peculiar to slag is effectively used as a roadbed material or the like. Moreover, since slow cooling slag has the property equivalent to a natural stone, it is effectively used also as an aggregate for concrete.

  On the other hand, steelmaking slag includes hot metal pretreatment slag, converter slag, electric furnace slag, stainless steel slag, etc. produced in a process of producing steel by refining pig iron and scrap produced in a blast furnace. These are generated and discharged and then slowly cooled to crush the rocks and adjust the particle size.

Among these, steelmaking slag has a high basicity (expressed as CaO / SiO ₂ ) and contains a large amount of free CaO, so it easily absorbs moisture and expands. It is used as a civil engineering / construction material like blast furnace slag. However, the processing is extremely difficult.

  Therefore, some attempts have been made to actively utilize such steelmaking slag.

  A typical application is a hydrated hardened body using steel slag. In particular, a hydrated and hardened body using steelmaking slag has high strength and is suitable for high value-added applications such as roadbed materials and concrete blocks.

  However, when manufacturing a hydrated and hardened body using steelmaking slag, there is a problem that if the steelmaking slag having a high water immersion expansion rate is used, the hardened body is cracked by rainwater or the like.

  Therefore, in order to solve the above problem, for example, in Patent Document 1, aging-treated steelmaking slag is used as an aggregate, and blast furnace slag fine powder is used as an alkali stimulating material, so that the periphery of steelmaking slag particles is densely hydrated. A solidified body with a structure surrounded by products is proposed.

  However, in the aging treatment of steelmaking slag described in Patent Document 1, as shown in Tables 3 and 4, aging exposed to water vapor at normal pressure (hereinafter referred to as atmospheric pressure steam aging) is natural aging for several days. For several months and requires a long time for processing. In addition, whether atmospheric steam aging or natural aging satisfies the water expansion rate of the steelmaking slag solidified body over a long period is unknown.

  Moreover, in patent document 2, the technique which suppresses a water immersion expansion rate by the steel-making slag solidified body using the steel-making slag which adjusted basicity is proposed.

  However, as in the technique proposed in Patent Document 2, in order to satisfy the water expansion rate of steelmaking slag only by adjusting the basicity without performing an aging treatment, the frequency of component management of the steelmaking slag is set. It is necessary to raise. That is, due to variations in the components in the steelmaking slag, a part of the solidified steelmaking slag expands and cracks are generated due to collapse.

  Thus, various inventions related to aging of steelmaking slag have been disclosed so far. For example, the applicant exposes a steelmaking slag having a particle size of 40 mm or less to 80% or more to a saturated steam atmosphere at a pressure of 0.2 to 1.0 MPa in a pressure vessel for 1 to 5 hours. Patent Document 3 proposes an invention that promotes the aging of steelmaking slag.

  In Patent Document 3, when the inside of the pressure vessel is held in a saturated steam atmosphere at a pressure of 0.2 to 1.0 MPa within 5 hours, the operation of temporarily reducing the pressure inside the pressure vessel is performed once or twice. An invention has also been proposed in which the water expansion coefficient is further reduced by repeating the process more than once.

JP 2004-292295 A JP 2008-280224 A JP 2007-106631 A

  The problem to be solved by the present invention is that a conventional solidified body having a structure in which a dense hydration product surrounds steelmaking slag particles subjected to atmospheric pressure steam aging treatment takes a long time for aging treatment, It is unclear whether the expansion coefficient is satisfied over a long period of time. In addition, the technology to manufacture only by adjusting the basicity without performing the aging treatment causes a part of the solidified body to expand due to variations in the components in the steelmaking slag, resulting in cracks due to collapse. The problem is that there is a problem in maintenance management.

  An object of the present invention is to provide a high-quality steelmaking slag hydrated solid body that can be aged for a short time and that does not crack due to expansion even when used for a long time, and a method for producing the same. .

The steelmaking slag hydrated cured body of the present invention is
A steelmaking slag having a particle size of less than 5 mm that has been subjected to an aging treatment in a steam atmosphere at a pressure of 0.2 to 1.0 MPa alone,
Or
A particle size obtained by mixing the steelmaking slag with a blast furnace slag having a particle size of less than 5 mm as a fine aggregate and subjected to an aging treatment in a steam atmosphere at a pressure of 40 to 60% by mass and a pressure of 0.2 to 1.0 MPa. A steelmaking slag of 5 mm or more and less than 40 mm is used as a coarse aggregate with 20 to 40% by mass and solidification aid 10 to 30% by mass, with admixture and alkali stimulant added as necessary ,
The most important feature is that it has been solidified.

The steelmaking slag hydrated cured body of the present invention is,
A steelmaking slag having a particle size of less than 5 mm which has been subjected to an aging treatment in a steam atmosphere at a pressure of 0.2 to 1.0 MPa;
Or
A mixture of the steelmaking slag and blast furnace slag having a particle size of less than 5 mm is used as a fine aggregate, and the particle size is 5 mm when subjected to an aging treatment in a steam atmosphere at a pressure of 0.2 to 1.0 MPa. Above, what added the admixture and the alkali stimulating agent as needed to the total amount of 20 to 40% by mass of steelmaking slag of less than 40 mm as coarse aggregate and 10 to 30% by mass of the solidification aid,
Manufactured by driving into a block of a predetermined size and curing. This is the method for producing the hydrated and hardened steel slag of the present invention.

  In the present invention, since the aging treatment is performed in a steam atmosphere at a pressure of 0.2 to 1.0 MPa, the time required for the aging treatment can be shortened, and the water immersion expansion coefficient is set to JIS A 5015 “steel for roads”. It can be reduced to 1.5% or less as defined by “slag”.

  According to the present invention, since the aging treatment is performed in a steam atmosphere at a pressure of 0.2 to 1.0 MPa, the aging treatment can be performed in a short time, and there is no cracking due to expansion even when used for a long time. A high quality steelmaking slag hydrated solid body can be obtained.

It is a figure explaining the pressurization type steam aging process at the time of manufacturing the solidification object of the present invention. It is the figure which showed an example of the relationship between the aging time in various aging methods, and the change of a water immersion expansion coefficient. It is the figure which showed the relationship between the natural aging progress days and the expansion rate at the time of performing the natural aging process further for the steelmaking slag after a pressurization type steam aging process.

  An object of the present invention is to provide a high-quality steelmaking slag hydrated solidified body that can be aged for a short time and does not crack due to expansion even when used for a long time, and a method for producing the same. It is.

  Then, for the purpose, for example, steelmaking slag having a particle size of less than 5 mm subjected to an aging treatment in a steam atmosphere at a pressure of 0.2 to 1.0 MPa is individually poured into a block having a predetermined size, and is cured and molded. Realized by solidification.

The present invention will be described below.
As a result of intensive studies to solve the above problems, the inventors have found that aging treatment can be performed in a short time by aging steelmaking slag in a pressurized steam atmosphere. Furthermore, if a hydrated and hardened body is formed using steelmaking slag that has been aged in a pressurized steam atmosphere, the water expansion coefficient is low regardless of the particle size, and cracking due to expansion is unlikely to occur even after long-term use. It has been found that it becomes a high-quality solidified body.

  It is preferable to use steel slag, which is used as an alternative to natural crushed stone, for the fine aggregate and coarse aggregate used in the production of the solidified body of the present invention. In particular, it is preferable to use a steelmaking slag that has an absolute dry density higher than that of natural crushed stone and that has a solidified body that is denser and has improved physical properties such as compressive strength. Even if this steelmaking slag is mixed with blast furnace slag, the same effect is exhibited.

  Steelmaking slag used in fine aggregate and coarse aggregate is refined pig iron and scrap produced in a blast furnace, and hot metal pretreatment slag, converter slag, electric furnace slag generated in the process of producing steel, These are stainless steel slag, etc., which are crushed and sized. In addition, blast furnace slag used for fine aggregates includes blast furnace slow-cooled slag and granulated blast furnace slag. These crushed and sized particles are used alone or in combination.

  For the fine aggregate, steelmaking slag having a particle size of less than 5 mm is used. Further, as the coarse aggregate, a steelmaking slag having a particle size of 5 mm or more and 40 mm or less, preferably a steelmaking slag having a particle size of 5 mm or more and 25 mm or less is used.

  The steelmaking slag used as a fine aggregate has a particle size of less than 5 mm, and the steelmaking slag used as a coarse aggregate has a particle size of 5 mm or more and 40 mm or less. Because. In particular, if the particle size of steelmaking slag used as coarse aggregate exceeds 40 mm, the time required for uniform mixing treatment becomes longer, the workability becomes worse, and the specific surface area becomes larger and latent hydraulic properties are exhibited. This is because it may not be done.

  In the present invention, a steelmaking slag having a particle size of less than 5 mm, which has been subjected to an aging treatment in a steam atmosphere at a pressure of 0.2 to 1.0 MPa, or the steelmaking slag and a blast furnace slag having a particle size of less than 5 mm is used. A steel aggregate slag having a particle size of 5 mm or more and less than 40 mm, which has been subjected to aging treatment in a steam atmosphere at a pressure of 40 to 60 mass% and a pressure of 0.2 to 1.0 MPa, is obtained by using a mixture of 20 to 40% by mass, and a total of 100% by mass containing 10 to 30% by mass of a solidifying auxiliary material are cast into a block of a predetermined size, cured and solidified by molding.

  The range of the blending ratio of fine aggregate, coarse aggregate, and solidification aid is based on the type and particle size of steelmaking slag and blast furnace slag, and the particle size of the solidification aid. The test was conducted and found from the results.

  The result of the confirmation test is that the fine aggregate is 40% by mass or more and 60% by mass or less, the coarse aggregate is 20% by mass or more and 40% by mass or less, and the solidification aid is 10% by mass or more and 30% by mass or less. This is because the compression strength of the solidified body is insufficient in any case outside the above range. On the other hand, it is because it is possible to satisfy the grain size standards for roadbed materials, concrete blocks, etc., and to further ensure the strength within the above blending ratio range.

  Next, the pressurized steam aging treatment when producing the solidified body of the present invention will be described with reference to FIG.

  The steelmaking slag 3 after crushing and sizing stored in the slag container 2 is charged into the pressure container 4 by the carry-in / out device 1 (in the direction of the white arrow in FIG. 1). After charging, the open / close lid 4a is closed to seal the pressure vessel 4, and then the pressurized steam is supplied from the pressurized steam supply piping system 5 to heat the steelmaking slag 3 in the pressure vessel 4. While discharging the hot water condensed by this heating from the drain valve 4b, the inside of the pressure vessel 4 is heated and pressurized to age the steelmaking slag 3 to a predetermined pressure for a predetermined time. In addition, 4c in FIG. 1 is an exhaust device.

  There are the following three methods for the pressurized steam aging treatment of the steelmaking slag 3 using the pressure vessel 4.

(Method 1):
A method of holding the inside of the pressure vessel 4 in a saturated steam atmosphere at a pressure of 0.2 MPa or more and 1.0 MPa or less for 5 hours or more, and then reducing the inside of the pressure vessel 4 to atmospheric pressure and discharging it.

  In the steelmaking slag in which undehydrated lime and undehydrated magnesium oxide are simultaneously present, the hydration reaction tends to be remarkably slow. Therefore, when the aging time is less than 5 hours, the water expansion coefficient is 1.5. It was impossible to decrease to less than%.

  However, even in the case of steelmaking slag in which undehydrated lime and undehydrated magnesium oxide are present at the same time, if the aging is maintained for 5 hours or more, preferably about 16 hours, the water-expanded expansion is maintained. It has been found that the rate can be reduced to 1.5% or less.

  Of course, it is possible to arbitrarily adjust the required time by measuring the water expansion rate after aging to cope with the change in the content of undehydrated lime and undehydrated magnesium oxide, which are the main factors of expansion. It is.

  Incidentally, FIG. 2 shows the relationship between the aging time for each pressurizing pressure and the change in the water expansion coefficient when aging is performed by the method 1. FIG. 2 shows, as a comparison, the relationship between the aging time and the change in the water immersion expansion rate when atmospheric pressure steam aging and natural aging are performed.

  From FIG. 2, it can be seen that the water immersion expansion rate specified by JIS A 5015 “Steel Slag for Roads” can be satisfied by securing an aging time of 5 hours or more as in Method 1 above.

(Method 2):
Operation of temporarily reducing the pressure inside the pressure vessel 4 and restoring the pressure again during the process of maintaining the inside of the pressure vessel 4 in a saturated steam atmosphere at a pressure of 0.2 MPa or more and 1.0 MPa or less for 5 hours or more A method in which the inside of the pressure vessel 4 is depressurized to atmospheric pressure and discharged after being performed more than once.

  Steelmaking slag has many pores inside. The moisture contained in the pores evaporates due to the reduced pressure, expands the volume and is released to the outside of the particles, thereby expanding or breaking the particle gap. The steelmaking slag whose particle gaps are widened or broken in this way is easily exposed to steam at the center, so that the aging speed is increased. In particular, when aging is performed for a long time of 5 hours or more, the operation is remarkably manifested by repeating the operation of temporarily reducing the internal pressure of the pressure vessel to 50% or less of the pressure before the reduction several times. Furthermore, it becomes possible to reduce the water immersion expansion rate of the steelmaking slag.

(Method 3):
A method of further performing atmospheric pressure steam aging treatment or natural aging treatment on the steelmaking slag after the pressurized steam aging treatment obtained by Method 1 or Method 2. In this case, as is apparent from FIG. 3, the expansion reaction can be further promoted.

  In the above methods 1 to 3, the pressure of the saturated steam atmosphere inside the pressure vessel is set to 0.2 MPa or more and 1.0 MPa or less. When the pressure is less than 0.2 MPa, the effect of the pressurized steam aging is obtained. Because it is not possible. On the other hand, although it is technically possible to increase the reaction rate even at a pressure exceeding 1.0 MPa, it is necessary to take a rigorous response to equipment maintenance and management, etc. Because it is not realistic.

  As the solidification aid used in producing the steelmaking slag hydrated cured product of the present invention, it is preferable to use a silica-containing substance, a pozzolanic material, gypsum, and Portland cement. Examples of the silica-containing substance and the pozzolanic material include coal ash, various cements (blast furnace cement, silica cement, fly ash cement, etc.), blast furnace slag fine powder, and the like. From the viewpoint of effective use of steel slag, blast furnace slag fine powder, blast furnace cement, and fly ash are more preferable. These may be used alone or in combination of two or more.

  Moreover, as an admixture added as necessary when producing the steelmaking slag hydrated cured product of the present invention, a cationic surfactant, an anionic surfactant, a nonionic surfactant, an amphoteric surfactant, Listed are dispersants containing a polymeric dispersant and the like.

  Among these, examples of the cationic surfactant include alkyltrimethylammonium chloride, alkylbenzylammonium chloride, and dialkyldimethylammonium bromide.

  Examples of the anionic surfactant include sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium dodecanoate, and sodium stearate.

  Examples of nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, and sucrose fatty acid ester.

  Examples of amphoteric surfactants include alkylbetaines such as alkyldimethylaminoacetic acid betaines, alkylimidazolines, and the like.

  In addition, as the polymer-type water-dispersing agent, naphthalene sulfonate formalin condensate, polystyrene sulfonate, polyacrylate, salt of vinyl compound and carboxylic monomer copolymer, carboxymethyl cellulose, Examples include polyvinyl alcohol.

  These admixtures are preferably added in an amount of 0.1 to 5% by mass based on the total amount (100% by mass) of the fine aggregate, coarse aggregate and solidification aid. The admixture is used for adjusting the setting speed, and if it is less than 0.1% by mass, the effect of the setting speed cannot be obtained, and if it exceeds 5% by mass, the compressive strength cannot be obtained, which is not preferable. .

  Moreover, when manufacturing the steelmaking slag hydration hardening body of this invention, you may add an alkali stimulating material as needed. Here, as the alkali stimulating material, alkaline earth metal hydroxide such as sodium hydroxide, calcium hydroxide, sodium carbonate, calcium carbonate, carbonate, sulfate, chloride, or triethylamine, diethylamine, n-butylamine , Quaternary ammonium salts such as ammonia, tetramethylammonium hydroxide, tetramethylammonium fluoride, tetra n-butylammonium fluoride, benzyltrimethylammonium fluoride, etc. Etc.

  The alkali stimulating material is added to promote the pozzolanic reaction, and the amount to be added is preferably in the range of 0.1 to 5% by mass. If the amount is less than 0.1% by mass, the effect of promoting the pozzolanic reaction is low, and if it exceeds 5% by mass, the compressive strength decreases, which is not preferable.

  Although the test result performed in order to confirm the effect of this invention is demonstrated below, the invention example shown below does not limit the content of this invention.

  Tables 1 and 2 below show the test conditions of the invention examples, and Table 3 below shows the test results of the invention examples. The steelmaking slag used in this test was subjected to pressure-type steam aging treatment, and the particle size was adjusted. The kneaded product was poured into a mold to produce a cured body.

  The water expansion coefficient of the steelmaking slag hydrated cured body was measured in accordance with JIS A 5015. That is, the amount of strain obtained by immersing steelmaking slag in warm water at 80 ° C. and holding it in that state for 6 hours a day and measuring the amount of slag expansion with a strain gauge for 10 days. The compressive strength of the steelmaking slag hydrated cured product was measured according to JIS A 1108 when 28 days had passed after the production.

  The conditions for the comparative test are shown in Tables 4 and 5 below, and the test results are shown in Table 6 below. The same operations as in the inventive examples were performed except that the aging treatment method and the blending ratio of each raw material were changed.

As the evaluation methods shown in Tables 3 and 6, the compressive strength is 20 ° C. × 28 days after 20 N / mm ² or less x, 20 N / mm ² is exceeded, 30 N / mm ² or less is Δ, 30 N / A case of exceeding mm ² was evaluated as ◯, and if the water expansion coefficient was not less than 1.0%, it was evaluated as x even if the compression strength was achieved.

As is clear from Table 3 above, the compression strength after 20 ° C. × 28 days of the obtained cured product of the invention example was much higher than the target strength of 20 N / mm ² . Moreover, the water immersion expansion rate of the hardened body obtained in the present invention was far below the standard value of 1.5%, which is the standard value for road steel slag roadbed materials.

On the other hand, the compressive strength after 20 days at 20 ° C. of the cured body of the comparative example is 20 N / mm ² or less, which is the target strength, as is clear from Table 6 (Comparative Examples 9 to 17), or 20 N / mm ^2. The water immersion expansion rate exceeded 1.0% (Comparative Examples 1-8, 18-20).

  The present invention is not limited to the above example, and it goes without saying that the embodiments may be changed as appropriate within the scope of the technical idea described in each claim.

  For example, the steelmaking slag hydrated and cured product of the present invention may be produced by being crushed and granulated after being poured into a block having a predetermined size and cured.

3 Steelmaking slag 4 Pressure vessel 5 Pressurized steam supply piping system

Claims (9)

A steelmaking slag having a particle size of less than 5 mm, which has been subjected to steam aging treatment in a steam atmosphere at a pressure of 0.2 to 1.0 MPa,
Or
A particle size obtained by mixing the steelmaking slag with a blast furnace slag having a particle size of less than 5 mm as a fine aggregate and subjected to an aging treatment in a steam atmosphere at a pressure of 40 to 60% by mass and a pressure of 0.2 to 1.0 MPa. A steelmaking slag of 5 mm or more and less than 40 mm is used as a coarse aggregate with 20 to 40% by mass and solidification aid 10 to 30% by mass, with admixture and alkali stimulant added as necessary ,
A hydrated and hardened steelmaking slag characterized by being molded and solidified.   The steelmaking slag hydrated cured product according to claim 1, wherein an atmospheric pressure steam aging process or a natural aging process is performed after the pressurized steam aging process.   The steelmaking slag hydrated and hardened body according to claim 1 or 2, wherein the steelmaking slag is obtained by crushing and sizing a material formed in a refining vessel for melting molten steel.   The steelmaking slag hydration hardening according to any one of claims 1 to 3, wherein the blast furnace slag is one of blast furnace slow-cooled slag or granulated blast furnace slag, or a mixture of two kinds. body.   The steelmaking slag hydrated cured product according to any one of claims 1 to 4, wherein the solidification aid is a silica-containing material and a material having pozzolanic reactivity, or gypsum or Portland cement.   The admixture contains a surfactant, and is added in an amount of 0.1 to 5% by mass with respect to a total of 100% by mass of the fine aggregate, the coarse aggregate, and the solidification aid. The steelmaking slag hydration hardening body in any one of Claims 1-5.   The alkali stimulating material includes one or more of alkaline earth metal hydroxides, carbonates, sulfates, chlorides, amines, quaternary ammonium salts, and the like. The steelmaking slag hydrated cured product according to any one of claims 1 to 6, wherein 0.1 to 5 mass% is added to 100 mass% of the total of the coarse aggregate and the solidification aid. A steelmaking slag having a particle size of less than 5 mm, which has been subjected to a steam aging treatment in a steam atmosphere at a pressure of 0.2 to 1.0 MPa;
Or
A particle size obtained by subjecting the steel slag and blast furnace slag having a particle size of less than 5 mm to a fine aggregate to a steam aging treatment in a steam atmosphere of 40-60 mass% and a pressure of 0.2-1.0 MPa. A steelmaking slag of 5 mm or more and less than 40 mm is used as a coarse aggregate with 20 to 40% by mass and solidification aid 10 to 30% by mass, with admixture and alkali stimulant added as necessary ,
A method for producing a hydrated and hardened steelmaking slag, wherein the steelmaking slag is hardened by being poured into a block having a predetermined size.   It crushes and granulates after the said curing, The manufacturing method of the steel-making slag hydration hardening body of Claim 1 characterized by the above-mentioned.

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