JP3817698B2 - Anti-caking agent for granulated blast furnace slag - Google Patents

Description

The present invention relates to an anticaking agent for blast furnace slag.

  Blast furnace water granulated slag is one that has been subjected to rapid cooling and granulation by injecting pressurized water into blast furnace slag produced as a by-product in the ironmaking process, and in some cases re-pulverized to adjust the particle size.In recent years, as an alternative to natural sand, Used as civil engineering materials and concrete fine aggregates.

Such blast furnace granulated slag is generally stored outdoors for a long time because it is awaiting shipment or use, but if stored as it is, it will solidify and serve as a substitute for natural sand. I can't do that. Such slag consolidation is caused by the dissolution of CaO, Al ₂ O ₃ , MgO, and the like dissolved in the slag, and the increase in pH breaks the chain bonds of SiO ₂ and Al ₂ O ₃ in the slag. By forming and curing calcium silicate hydrate (C—S—H gel) and calcium aluminate hydrate (C—A—H gel).

  Conventionally, various anti-caking agents have been proposed in order to prevent caking during storage of such blast furnace granulated slag.

For example, Patent Document 1 below discloses an aliphatic oxycarboxylic acid, an aliphatic oxycarboxylate salt, or an aliphatic oxycarboxylate alkylene oxide adduct as an important component. Discloses an alkylene oxide adduct of an aliphatic oxycarboxylic acid and / or a salt thereof. Patent Document 3 listed below discloses a saccharide or a sugar alcohol that is a reduced derivative thereof as a main component, and Patent Document 4 discloses a component containing sorbitol as a main component. Furthermore, the following Patent Document 5 discloses a chemical for producing granulated blast furnace slag containing a polymer or copolymer which is a water-soluble monoethylenically unsaturated monomer (for example, sodium acrylate) as an essential constituent. Is disclosed, and it is described that the effect of preventing caking during storage is exhibited by the use of the drug. Patent Document 6 below discloses an anti-caking agent made of an acrylic acid polymer.
Japanese Patent Laid-Open No. 54-130596 JP 2001-58855 A JP 58-104050 A JP 59-116156 JP 54-96493 A JP 2003-160364 A

  Although the above conventional anti-caking agent can provide a certain level of anti-caking effect, it cannot be said to be sufficient, and is not satisfactory particularly in terms of the anti-caking effect during long-term storage.

This invention is made | formed in view of the above point, and it aims at providing the anti-caking agent of granulated blast furnace slag which can exhibit the anti-caking effect excellent over a long period of time.

  As a result of diligent research to solve the above problems, the present inventors have found that it is effective to use a carboxyl group-containing polymer and sorbitol together as an anti-caking agent for blast furnace granulated slag, and completed the present invention. It came to do.

That is, the present invention provides an anti-caking agent for granulated blast furnace slag containing a carboxyl group-containing polymer and sorbitol. Here, the blending amount of the carboxyl group-containing polymer is A, and the blending amount of sorbitol is B, so that A / B = 5/95 to 95/5.

The carboxyl group-containing polymer is a polymer of at least one monomer selected from the group consisting of acrylic acid, methacrylic acid and maleic acid, and has a mass average molecular weight of 1,000 to 500,000. Is preferred .

  According to the present invention, an excellent anti-caking effect can be obtained over a long period of time. Therefore, blast furnace granulated slag used as a substitute for natural sand can be stored safely for a long period of time. The number of uses can be reduced.

  Hereinafter, the present invention will be described in detail.

  The carboxyl group-containing polymer used in the anti-caking agent of the present invention is a polymer having a monomer (monomer) unit having a carboxyl group, and the carboxyl group may be in an acid state or a salt state.

  Specific examples include polymers such as acrylic acid, methacrylic acid, (anhydrous) maleic acid, (anhydrous) fumaric acid, itaconic acid, citraconic acid, and metaconic acid, and more preferably acrylic acid, Examples include homopolymers of methacrylic acid and maleic acid (polyacrylic acid, polymethacrylic acid, polymaleic acid and salts thereof), and copolymers obtained by appropriately combining these monomers. Two or more of these polymers can be used in combination. Examples of the salt when the carboxyl group is in a salt state include alkali metal salts such as sodium salt and potassium salt, alkaline earth metal salts such as calcium salt, and ammonium salt.

  The weight average molecular weight of the carboxyl group-containing polymer is preferably 1,000 to 500,000, more preferably 2,000 to 60,000. If the mass average molecular weight is less than 1,000, the persistence of the anti-caking effect is inferior (long-term effect is inferior), and if it exceeds 500,000, it cannot be supplied in liquid form and dissolved separately. This is not realistic because it requires a tank and increases costs.

  In addition, although the said patent document 1 describes that polyacrylic acid soda which is an anti-caking agent of urea is not effective as an anti-caking agent of granulated slag (Patent 2 page upper left column and page 3). In Comparative Example 1) and the present invention, as shown in the examples described later, by using in combination with sorbitol, an excellent anti-caking effect for granulated slag was found.

  Sorbitol used with the carboxyl group-containing polymer in the anti-caking agent of the present invention is a sugar alcohol having 6 carbon atoms.

  In the anti-caking agent of the present invention, the blending ratio of the carboxyl group-containing polymer and sorbitol is A / B = 5 by mass ratio, where A is the blending amount of the carboxyl group-containing polymer and B is the blending amount of sorbitol. / 95 to 95/5 is preferable. If the blending ratio of the carboxyl group-containing polymer is less than the above range, the initial caking prevention effect is particularly poor. Conversely, if the blending ratio of the carboxyl group-containing polymer is greater than the above range, the long-term effect is sustained. become weak.

  The anti-caking agent of the present invention is generally prepared in the form of an aqueous solution by dissolving the above components in water. Although the density | concentration of this aqueous solution is not specifically limited, Usually, 10-60 mass% is prepared by solid content concentration. In use, it is preferable to dilute the aqueous solution appropriately and apply it to the blast furnace granulated slag. In addition to the above components, additives such as preservatives can be added to the anti-caking agent within a range not impairing the effects of the present invention.

  The method for treating ground granulated blast furnace slag using the anti-caking agent of the present invention is not particularly limited. For example, a method of spraying an aqueous solution of anti-caking agent onto blast furnace granulated slag, a method of kneading an aqueous solution of anti-caking agent with blast furnace granulated slag, a method of immersing blast furnace granulated slag in an aqueous solution of anti-caking agent, etc. Is mentioned.

  The anti-caking agent of the present invention can also be added to pressurized water used at the time of crushing when producing granulated blast furnace slag to exert an anti-caking effect. That is, blast furnace granulated slag is manufactured by first crushing molten slag with pressurized water and dropping it into a stirring tank or a pit water tank, and then subjecting it to secondary crushing and cooling solidification to cause water granulation. . At this time, the pressurized water is normally circulated and used. However, the anti-caking agent of the present invention is added to the circulating water to give the anti-caking agent to the slag, thereby allowing the slag to be stored during subsequent storage. You may make it prevent caking.

  The amount of the anti-caking agent used for the granulated blast furnace slag is preferably 0.001 to 0.5% by mass, more preferably 0.01%, based on the dry mass of the granulated blast furnace slag. It is -0.1 mass%. By using such a use amount, a stable anti-caking effect can be exhibited over a long period of time, and when the treated blast furnace granulated slag is used as an aggregate for concrete, The strength can be prevented from being adversely affected.

  According to the present invention, the combined use of the carboxyl group-containing polymer and sorbitol can exert an excellent anti-caking effect over a long period of time against blast furnace granulated slag. It is thought that it is possible to suppress the increase in pH of the slag by acting on the eluted CaO, MgO, etc., and to slow down the hardening rate of the slag. It is done.

  Hereinafter, the present invention will be specifically described by way of examples, but the scope of the present invention is not limited thereto.

  According to the composition shown in Table 1 below, aqueous solutions (solid content concentration = 20 mass%) of the anti-caking agents of Examples and Comparative Examples were prepared. Here, Examples 1 to 9 are examples in which the carboxyl group-containing polymer and sorbitol are used in combination, Comparative Example 1 is an example in which no anti-caking agent is used, and Comparative Example 2 is an example in which sodium gluconate is used alone. Comparative Example 3 is an example of using sorbitol alone, and Comparative Example 4 is an example of using the carboxyl group-containing polymer alone.

  Polymers 1 to 6 and sorbitol in Table 1 are as follows.

Polymer 1: Polyacrylic acid Na having a mass average molecular weight of 5,000 (“AQUALIC DL365” manufactured by Nippon Shokubai Co., Ltd.)
Polymer 2: Polyacrylic acid Na having a weight average molecular weight of 10,000 (“Charol AN103P” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
Polymer 3: Na salt of acrylic acid and maleic acid copolymer having a weight average molecular weight of 5,000 (“AQUALIC TL-37” manufactured by Nippon Shokubai Co., Ltd.)
Polymer 4: Na salt of acrylic acid and maleic acid copolymer having a weight average molecular weight of 60,000 (“AQUALIC TL-300” manufactured by Nippon Shokubai Co., Ltd.)
Sorbitol: “Sorbit L-70” manufactured by Towa Kasei Kogyo Co., Ltd.

Polymer 5: Polyacrylic acid Na having a mass average molecular weight of 2,000 (“Aron A200U” manufactured by Toagosei Co., Ltd.)
Polymer 6: Polyacrylic acid Na having a mass average molecular weight of 500,000 (“Charol AN304P” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
Blast furnace granulated slag (coarse grain ratio = 2.59) adjusted to a water content of 5% by mass and a specific surface area of 0.040 m ² / kg is charged into the mixing kettle, and the addition rate of anti-caking agent is based on the dry slag mass. The mixture was stirred with a hand shovel while spraying an aqueous solution of each anti-caking agent to 0.02 mass%, and then mixed at a low speed for 5 minutes with a mortar mixer. The coarse particle ratio of slag was calculated according to JIS A1102 “Aggregate Screening Test Method”: coarse particle ratio = (sum of mass percentages of samples remaining in each sieve) / 100.

100 g of the treated slag was placed in an 80 mL aluminum bag, sealed and stored at 60 ° C. The specific surface area of each sample after 5 days, 10 days, 20 days, and 30 days from the start of storage was measured using “ATOSORB series 1” manufactured by Cantachrome. The results are shown in Table 1. As slag hardens, crystals such as calcium silicate or aluminum silicate grow from the surface of the slag, which increases the specific surface area of the slag. Means excellent.

  As shown in Table 1, in Examples 1 to 9 in which a carboxyl group-containing polymer and sorbitol are used in combination, an increase in the slag specific surface area after long-term storage can be suppressed as compared with the anti-caking agent of the comparative example, Therefore, the anti-caking effect in long-term storage was excellent.

Claims (2)

Carboxyl group-containing polymer and sorbitol Ri Na contain, the amount of the carboxyl group-containing polymer A, the amount of sorbitol as B, formulated at a weight ratio of A / B = 5 / 95~95 / 5 Anti-caking agent for granulated blast furnace slag. The carboxyl group-containing polymer is a polymer of at least one monomer selected from the group consisting of acrylic acid, methacrylic acid and maleic acid, and has a mass average molecular weight of 1,000 to 500,000. The anti-caking agent for granulated blast furnace slag according to claim 1.