JP2007290905A - Anti-solidifying agent for granulated blast furnace slag, granulated blast furnace slag, and anti-solidifying method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an anti-solidifying agent and an anti-solidifying method obtaining a sufficient anti-solidifying effect for a long period of time even when there is rainfall in open storage, in the anti-solidification by adding the anti-solidifying agent to the granulated blast furnace slag. <P>SOLUTION: The anti-solidifying agent comprises at least one selected from among an Na-salt of oxycarboxylic acid and an Na-salt of an acrylic acid polymer and at least one selected from among carboxymethylcellulose, hydroxypropylcellulose, hydroxyethylcellulose, methyl cellulose, polyvinyl acetate, and polyvinyl alcohol. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to prevention of caking of blast furnace granulated slag. More specifically, the present invention relates to an anti-caking agent for preventing caking, a blast furnace granulated slag to which the anti-caking agent is added, and an anti-caking method using the anti-caking agent.

  Granulated blast furnace slag is produced directly into sand by injecting high-pressure water into the molten slag discharged from the blast furnace and rapidly solidifying it. Blast furnace granulated slag can be finely pulverized into cement raw materials, used for civil engineering materials with as-manufactured grain size, or used for fine aggregates for concrete by adjusting the particle size and particle shape. Is done. The particle size and particle shape are adjusted by grinding the produced sand.

  By the way, there is a problem that blast furnace granulated slag is piled up for a long time before being used for fine aggregate for concrete, for example, and solidifies at that time. Blast furnace granulated slag, which has been refined by grinding, etc., is easy to consolidate.

  A number of anti-caking technologies have been proposed in the past, but methods using anti-caking agents include aliphatic oxycarboxylic acids and salts thereof (for example, see Patent Document 1), sugar alcohols (for example, patents). Reference 2), a polymer comprising a monoethylenically unsaturated monomer as a constituent (for example, see Patent Document 3), gluconic acid or a salt thereof (for example, see Patent Document 4), acrylic polymer (for example, , See Patent Document 5), and methods using anti-caking agents such as those containing phosphonic acid derivatives (see, for example, Patent Document 6).

Japanese Patent Laid-Open No. 54-130596 JP 58-104050 A JP 54-96493 A Japanese Patent Laid-Open No. 06-127986 JP 2003-160364 A JP 2005-82426 A

  Conventional anti-caking agents as disclosed in Patent Documents 1 to 6 can provide a certain degree of anti-caking effect in an indoor test or outdoors even in a short period of time. However, if there was rain when stored outdoors for a long time, the added anti-caking agent would flow out, and the effectiveness was reduced in a short period of time compared to avoiding rainfall indoors. Even in indoor storage, the anti-caking agent flowed down the slag when it was piled for a long time, and the content of the upper part decreased, and the expected effect could not be obtained.

  As countermeasures for the above problems, for example, it is conceivable to install a rain-proof roof even in outdoor storage, or to add to the extent that the amount of content decrease due to flow is grasped in advance and compensate for it. The rise was a problem.

  Therefore, the present invention has been made in view of such problems, and the purpose of the present invention is to reduce the outflow when there is rainfall during long-term outdoor storage, and to reduce the natural flow. An object of the present invention is to provide an anti-caking agent and an anti-caking method for blast furnace granulated slag capable of preventing caking, and to provide a granulated blast furnace slag that prevents caking for a long time.

In order to solve the above problems, the present invention
(1) at least one of a sodium salt of oxycarboxylic acid or a sodium salt of an acrylic acid polymer, and at least one of carboxymethylcellulose, hydroxypropylcellulose, hydroxyethylcellulose, methylcellulose, polyvinyl acetate or polyvinyl alcohol; An anti-caking agent for granulated blast furnace slag, which contains
(2) Consolidation of granulated blast furnace slag according to (1), wherein the sodium salt of oxycarboxylic acid is sodium gluconate, a sodium salt of a derivative of gluconic acid, or trisodium citrate Inhibitor.
(3) The anti-caking agent for granulated blast furnace slag according to (1), wherein the sodium salt of the acrylic acid polymer is sodium polyacrylate.
(4) A granulated blast furnace slag characterized by adding the anti-caking agent according to any one of (1) to (3).
(5) An anti-caking method using the anti-caking agent according to any one of (1) to (3), wherein a sodium salt of oxycarboxylic acid or a sodium salt of acrylic acid polymer At least one kind is added to the granulated blast furnace slag, and then at least one of carboxymethyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, methyl cellulose, polyvinyl acetate or polyvinyl alcohol is added to the granulated blast furnace slag. , How to prevent consolidation of granulated blast furnace slag.
I will provide a.

  According to the present invention, a sufficient anti-caking effect can be obtained without increasing costs by reducing the loss of anti-caking agent of granulated blast furnace slag due to rainfall or natural flow during outdoor long-term storage. .

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  The anti-caking agent for granulated blast furnace slag according to the present invention comprises at least one of an oxycarboxylic acid Na salt or an acrylic acid polymer Na salt, carboxymethylcellulose, hydroxypropylcellulose, hydroxyethylcellulose, methylcellulose, polyacetic acid. Contains at least one of vinyl and polyvinyl alcohol.

  Hereinafter, in the present invention, at least one of Na salt of oxycarboxylic acid or Na salt of acrylic polymer is referred to as “caking retarder”. Further, at least one of carboxymethylcellulose, hydroxypropylcellulose, hydroxyethylcellulose, methylcellulose, polyvinyl acetate or polyvinyl alcohol is referred to as “water-soluble polymer”.

  In the present invention, the caking prevention is mainly performed by a caking retarder. If at least one of an oxycarboxylic acid Na salt or an acrylic acid polymer is contained, the anti-caking property is sufficient. The caking retarder is used as a sodium (Na) salt so as to reduce the interaction with the water-soluble polymer and to exhibit pH buffering properties against slag exhibiting alkalinity.

  In the present invention, a water-soluble polymer prevents a caking retarder corresponding to a conventional caking inhibitor from being washed away by rain or natural flow. The water-soluble polymer adheres to the slag surface in the form of a film and fixes the setting retarder on the slag surface. Furthermore, a water-soluble one is used so that it can be mixed with the caking retarder without separation and can sufficiently penetrate between the slag particles. Although it is more preferable if the water-soluble polymer itself exhibits anti-caking ability, it is not essential in the present invention.

  As water-soluble polymers, natural polymers such as cellulose derivatives and their Na salts are suitable for the purpose of preventing caking retarders from being washed away by rain or natural flow. Among them, carboxymethyl cellulose, hydroxypropyl, and the like. Cellulose, hydroxyethyl cellulose, and methyl cellulose have a great effect of preventing the set retarder from flowing out. Furthermore, it has been found by the present inventors that carboxymethylcellulose has a caking prevention effect although it is weak. Synthetic polymers such as polyvinyl acetate and polyvinyl alcohol are also water-soluble and film-forming, and have an effect of preventing outflow.

  The mixing ratio of the water-soluble polymer in the anti-caking agent in the present invention is preferably 20 to 60% by mass. More preferably, it is about 45-55 mass%. If it is less than 20% by mass, the effect of adhering to the surface of the slag in the form of a film cannot be obtained sufficiently, and the anti-caking effect is comparable to that of conventional anti-caking agents. Even if it exceeds 60% by mass, the outflow prevention effect is not improved so much.

  The Na salt of oxycarboxylic acid, which is the caking retarder of the present invention, is Na gluconate, Na salt of gluconic acid derivative, or TriNa citrate (hereinafter, Na tricitrate is simply referred to as Na citrate). More preferably. Gluconic acid is obtained, for example, by hydrolysis and oxidation of glucose, and is further neutralized and used as a Na salt. Among the derivatives of gluconic acid, optical isomers such as gulonic acid are particularly preferred, but other derivatives can also be used because they have an anti-caking effect. Na salt neutralized with citric acid is also used. This is because the Na salt has a more buffering effect against the increase in pH, which is one of the causes of consolidation. By the way, although these salts are obtained by crystallization from an aqueous solution, it is not particularly necessary to once convert the slag into a solid because it is added as an aqueous solution.

  The concentration of the caking retarder in the prepared aqueous solution is grasped, and when it is added to the slag, it may be diluted to a predetermined concentration (details will be described later).

  The Na salt of the acrylic acid polymer that is the caking retarder of the present invention is more preferably polyacrylic acid Na. Acrylic acid polymers include acrylic esters, methacrylic acid, and copolymers of these, but the highest anti-caking effect is obtained with only one carboxyl group in the structural unit. The present inventors have found that this is a Na salt of polyacrylic acid.

  In the present invention, as a setting retarder, a compound having a structure in which a carboxyl group and a hydroxyl group are bonded to one carbon as shown in the following chemical structural formula (1), or shown in the following chemical structural formula (2) At least one of the compounds having a structure in which a carboxyl group is bonded to each of two different carbons bonded to one carbon is used. Examples of the compound having the structure shown in the chemical structural formula (1) include oxycarboxylic acids such as gluconic acid and citric acid, and examples of the compound having the structure shown in the chemical structural formula (2) include acrylic. There are acid polymers and citric acid.

  In this invention, it is preferable that the addition amount of a caking retarder is 0.01-0.1 mass% with respect to blast furnace granulated slag. If it is less than 0.01% by mass, a sufficient anti-caking effect cannot be obtained. On the other hand, if 0.1% by mass is added, a sufficient anti-caking effect can be obtained, and addition beyond this is excessive in cost. More preferably, it is 0.03-0.06 mass%.

  As a caking prevention method in the present invention, it is recommended to add a water-soluble polymer to the blast furnace granulated slag after adding a caking retarder to the blast furnace granulated slag. In the present invention, it is possible to obtain a sufficient anti-caking effect by adding an aqueous solution obtained by mixing a caking retarder and a water-soluble polymer to the blast furnace granulated slag at a time. A retarder is added to adhere to the slag surface, and then a water-soluble polymer is added to cover the slag surface to which the caking retarder is adhered so that the caking retarder does not easily flow out of the slag. To do.

  The anti-caking agent can be added by, for example, slag thinly spread on a belt conveyor and continuously flowing, and spraying an aqueous solution in which the anti-caking agent is dissolved onto the slag, or a slag and a predetermined amount of solidification on a rotary mixer. There is no particular limitation as long as it can be sufficiently mixed with the slag, for example, by adding and mixing an aqueous solution in which an anti-caking agent is dissolved. In the method of adding a water-soluble polymer after adding a caking retarder, for example, slag is laid thinly on a belt conveyor and continuously flowed, and an aqueous solution in which the caking retarder is dissolved is sprayed on the slag. Subsequently, an aqueous solution in which the water-soluble polymer is dissolved is sprayed. If the belt conveyor is connected between two sprays, the setting retarder can be adhered more uniformly, which is effective. When mixing with a rotary mixer, first, an aqueous solution in which a slag and a predetermined amount of a set retarder are dissolved is added and mixed, and then an aqueous solution in which a water-soluble polymer is dissolved is added and mixed.

  The amount of the aqueous solution in which the anti-caking agent is dissolved is preferably 1 to 10% by mass with respect to the granulated blast furnace slag. If it is less than 1% by mass, it is difficult to uniformly adhere to the entire slag. On the other hand, when it is more than 10% by mass, the anti-caking agent flows out without being held by the slag. Usually, granulated blast furnace slag has a water content ratio of just over a few percent after production, so the amount of aqueous solution in which the anti-caking agent is dissolved is adjusted so that the water content ratio is 8 to 15% by mass with this water content. It is preferable.

  The concentration of the anti-caking agent in the aqueous solution is preferably adjusted so that 0.01 to 0.1% by mass is added to the blast furnace granulated slag as an anti-caking agent.

  The mass% of water in the present invention is a water content ratio measured by JIS A1203.

  Table 1 shows examples of the present invention, and Table 2 shows comparative examples.

  The sample to which the anti-caking agent of the example was added was rotated while putting a granulated blast furnace slag having a maximum particle size of less than 5 mm and a coarse particle ratio of 2.5 (measured according to JIS A0203) into a rotary mixer, It was prepared by spraying an aqueous solution in which a predetermined amount of anti-caking agent was dissolved. For samples using the method of adding a water-soluble polymer after adding a caking retarder, first add the aqueous solution in which the caking retarder is dissolved while mixing the slag into the mixer, and then mix. An aqueous solution in which a water-soluble polymer was dissolved was added and prepared.

  Next, blast furnace granulated slag added with an anti-caking agent was filled into a mold having an inner diameter of 50 mm and a height of 100 mm, and compacted at an absolute pressure of 0.15 MPa to prepare a compact. The purpose of the present invention is to reduce the loss of the anti-caking agent due to rain. Therefore, for some samples, a hole is provided in the bottom of the mold, and pure water with a mass of 20% by mass of slag is added from the top of the slag compact. A sample that was gently and uniformly poured (watered) and was affected by rainfall was created.

  A sample that was affected by rain due to water flow and a sample that did not pass water were both sealed and cured at 60 ° C. so as not to dry. The curing period was 1 week, 2 weeks, 4 weeks, 8 weeks, and 12 weeks. When the predetermined curing period was over, the molded body obtained by opening the mold was sieved with a sieve having an opening of 5 mm, and the degree of consolidation was compared by the ratio of the mass remaining on the sieve.

  The anti-caking agent component column in the examples of Table 1 shows the caking retarder in the upper row and the water-soluble polymer in the lower row. The mixing ratio of the caking retarder and the water-soluble polymer is shown in the right column. The addition amount of the anti-caking agent of the Example was 0.06 mass% with respect to the granulated blast furnace slag. Since the water content ratio of the granulated blast furnace slag used in this test was 7% by mass, an aqueous solution having an anti-caking agent concentration of 1% by mass was added by 6% by mass to the granulated blast furnace slag. , 0.06% by mass of an anti-caking agent was added to the granulated blast furnace slag.

  Furthermore, when the mixing ratio of the caking retarder and the water-soluble polymer is 50% by mass, an aqueous solution mixed and adjusted so that the concentration is 0.5% by mass and 1% by mass in total is added to the granulated blast furnace slag. In an example of adding 6% by mass or adding a water-soluble polymer later, add 1% by mass of each of a caking retarder and a water-soluble polymer to 3% by mass of each granulated blast furnace slag. Thus, 0.06% by mass of an anti-caking agent was added to the granulated blast furnace slag.

  In Example 1, an anti-caking agent containing 50% by mass of Na gluconate and CMC (carboxymethylcellulose) was added, followed by curing after passing 20% by mass of pure water. In the 1st and 2nd weeks, the whole amount passed through the 5mm sieve and no caking occurred. However, 40% by mass in the 4th week and 100% by mass in the 8th week remained on the sieve, and the whole sample was consolidated. Judged that.

  In Example 2, an anti-caking agent containing 50% by mass of Na citrate and CMC was used. In Example 2, since it was determined that caking occurred in the entire sample in the 12th week later than Example 1, Na citrate is considered to have a better anticaking effect than Na gluconate.

  Example 3 is an example in which the water-soluble polymer of Example 1 was replaced with HPC (hydroxypropylcellulose). The anti-caking effect of Example 3 and the period until caking occurred were almost the same as those of Example 1.

  Example 4 is an example in which the water-soluble polymer of Example 2 was replaced with HPC. The anti-caking effect of Example 4 and the period until caking occurred were almost the same as in Example 2.

  Examples 5 and 6 are examples in which the main anti-caking agent is the same as in Examples 1 and 2, and HEC (hydroxyethyl cellulose) is used as the water-soluble polymer. The anti-caking effect of Examples 5 and 6 was almost the same as Examples 1 and 2 or slightly reduced.

  Examples 7 and 8 are examples in which the main anti-caking agent is the same as in Examples 1 and 2, and MC (methyl cellulose) is used as the water-soluble polymer. Examples 7 and 8 had almost the same anti-caking results as Examples 5 and 6.

  In Examples 9 and 10, the main anti-caking agent is the same as in Examples 1 and 2, respectively, and the water-soluble polymer is changed to polyvinyl acetate in Examples 9 and 10, and Examples 11 and 12 are used. In this example, polyvinyl alcohol is used. The caking prevention effects of Examples 9, 10, 11 and 12 were slightly lower than those of Examples 1 and 2, respectively, but practically the same level.

  Examples 13 to 18 are examples in which polyacrylic acid Na was used as a main anti-caking agent, and CMC, HPC, HEC, MC, polyvinyl acetate, and polyvinyl alcohol were mixed as water-soluble polymers, respectively. The main anti-caking agent had a slightly lower anti-caking effect than Na gluconate and Na citrate, but was practically usable.

  In Example 19, an anti-caking agent having a CMC mixing ratio of 30% by mass with respect to Example 1 was used. When the amount of the water-soluble polymer is decreased, the coating effect is reduced, but the effect of preventing caking is improved by the amount of caking retarder, so the result was almost the same as in Example 1 when water was passed.

  In Example 20, an anti-caking agent having a CMC mixing ratio of 60% by mass with respect to Example 2 was used. When the amount of the water-soluble polymer is increased, the anti-runoff effect is improved. However, since the anti-caking effect is reduced by the amount of the caking retarder, the result is almost the same as in Example 2 when water is passed.

  Examples 21, 22, and 23 are examples in which a water-soluble polymer was added later to Examples 1, 2, and 17, respectively. By adding it later, the film effect of the water-soluble polymer worked effectively, and in each of Examples 21, 22, and 23, the anti-caking effect continued for a longer period.

  On the other hand, Examples 24 and 25 are cases where water was not passed through Examples 1 and 2, respectively. Since there was no outflow of the anti-caking agent due to water flow, it was possible to prevent caking for a longer period than in Examples 1 and 2.

  Next, the comparative example of Table 2 is an example in which only the main caking retarder in the examples was added. The water content of the granulated blast furnace slag used in the test was 5% by mass, the same as in the example. In order to make the addition amount of the main anti-caking agent the same as in the example, an aqueous solution having a main anti-caking agent concentration of 0.5 mass% was added to the blast furnace granulated slag at 6 mass%.

  In Comparative Example 1, 0.03% by mass of Na gluconate was added to granulated blast furnace slag, and 20% by mass of pure water was passed through. It is thought that Na gluconate flowed out by passing water, and the caking is remarkably compared with Examples 1, 3, 5, 7, 9, 11, 19, 21, 24 where the main anti-caking agent is Na gluconate. Proceeded quickly. Comparative Example 2 is an example using Na polyacrylate, but although it is thought that it is less likely to flow out than Comparative Example 1, it is harder than the case where Na polyacrylate in Examples 13-18 and 23 is used. The progress was fast.

  On the other hand, Comparative Examples 3 and 4 are examples when water was not passed through Comparative Examples 1 and 2, respectively. In the absence of water flow, that is, in the absence of rain, any anti-caking agent had a long-term anti-caking effect. On the other hand, when the anti-caking agent of Comparative Example 5 was not added, caking occurred very quickly. In addition, as in Comparative Example 1, if there was an outflow due to rain at an early stage when the anti-caking agent was added, the caking was facilitated to the same extent as when no anti-caking agent was added.

As mentioned above, although preferred embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to this example. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

Claims (5)

At least one of a sodium salt of an oxycarboxylic acid or a sodium salt of an acrylic acid polymer;
At least one of carboxymethylcellulose, hydroxypropylcellulose, hydroxyethylcellulose, methylcellulose, polyvinyl acetate or polyvinyl alcohol;
An anti-caking agent for granulated blast furnace slag, which contains   The anti-caking agent for granulated blast furnace slag according to claim 1, wherein the sodium salt of oxycarboxylic acid is sodium gluconate, a sodium salt of a derivative of gluconic acid, or trisodium citrate.   The anti-caking agent for granulated blast furnace slag according to claim 1 or 2, wherein the sodium salt of the acrylic acid polymer is sodium polyacrylate.   Blast furnace granulated slag, characterized in that the anti-caking agent according to any one of claims 1 to 3 is added. A caking prevention method using the caking inhibitor according to any one of claims 1 to 3, wherein at least one of a sodium salt of an oxycarboxylic acid or a sodium salt of an acrylic acid polymer is a blast furnace. After adding to the granulated slag, blast furnace granulated slag is characterized in that at least one of carboxymethylcellulose, hydroxypropylcellulose, hydroxyethylcellulose, methylcellulose, polyvinyl acetate or polyvinyl alcohol is added to the granulated blast furnace slag. How to prevent caking.