JP2010235383A - Method for producing modified granulated blast furnace slag and method for producing blast furnace cement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing modified granulated blast furnace slag by modifying the granulated blast furnace slag that is stored in an outdoor yard and deteriorated, and to provide a method for producing blast furnace cement, which is a new use of the modified water-granulated blast furnace slag and with which blast furnace cement is produced by using the deteriorated granulated blast furnace slag. <P>SOLUTION: The method for producing modified granulated blast furnace slag comprises a step of bringing the deteriorated component-stuck granulated blast furnace slag into contact with dilute sulfuric acid. The method for producing blast furnace cement comprises the steps of: preparing the modified granulated blast furnace slag by bringing the deteriorated component-stuck granulated blast furnace slag into contact with dilute sulfuric acid; and producing the blast furnace cement by using the modified granulated blast furnace slag. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a modified blast furnace granulated slag and a method for producing a blast furnace cement, and in particular, a modified blast furnace granulated slag for reforming a deteriorated blast furnace granulated slag to obtain a modified blast furnace granulated slag. The present invention relates to a production method and a method for producing a blast furnace cement in which blast furnace cement is produced using degraded blast furnace granulated slag.

Cement is widely used for concrete such as civil engineering structures and buildings, and soil reinforcement. This is because, by pouring mortar or concrete in which a mixture of cement and aggregate with water is poured into a mold, various shapes of structures can be manufactured, and the structures have high compressive strength. This is because there are advantages such as.
In addition, cement can be produced by calcining limestone and clay produced in large quantities, and can be used by mixing by-products from other industries such as blast furnace slag and fly ash.
These advantages make cement one of the most used industrial products.

  Among them, blast furnace cement (also called blast furnace slag cement) is a mixture of fine blast furnace slag powder obtained by grinding blast furnace granulated slag with a high vitrification rate, Portland cement, a small amount of gypsum powder, etc. It is a thing.

Granulated blast furnace slag is a multi-component inorganic substance produced as a by-product when producing pig iron in an iron blast furnace, and was manufactured by rapid cooling by water cooling the blast furnace slag in a molten state at 1300-1500 ° C. Is. In general, the SiO ₂ 30 to 35 wt%, the CaO 40 to 45 wt%, the MgO 2 to 9 wt%, the Al ₂ O ₃ containing 5 to 18 wt%, and as a minor component, TiO ₂ , CaS, FeO and the like.
The high furnace slag is a particulate material containing a large amount of glassy (diameter of several millimeters), the blast furnace slag in the grinding mill specific surface area 3500 cm ² / g or more, the high activity of the products 4000~6000cm ² / By crushing to g, it is used as a raw material for blast furnace cement.

  Moreover, it is said that the blast furnace cement of the outstanding performance can be manufactured by using the granulated blast furnace slag whose vitrification rate is 95% or more.

  When the blast furnace granulated slag is in an alkaline state where moisture is present, an alkaline substance such as CaO contained in the blast furnace granulated slag elutes in water and causes a hydration reaction while corroding its own glass structure. This is why it has a latent hydraulic property, which causes a hydration reaction similar to cement and hardens, and this is why blast furnace cement exhibits hydraulic properties similar to cement.

When producing blast furnace cement, calcium sulfate dihydrate (gypsum) is appropriately added to the above granulated blast furnace slag and finely pulverized to a predetermined fineness, or added to Portland cement or unground. Particulate slag and gypsum are added to the cement clinker and pulverized to a predetermined fineness.
The reason for adding gypsum during the production of Portland cement is to suppress rapid settling due to a rapid hydration reaction immediately after the injection of cement derived from tricalcium aluminate present in the cement. It is manufactured by adding about 5% gypsum. As a kind of gypsum to be added, chemical gypsum generated as a by-product from a chemical factory in addition to those produced naturally is mentioned, but both are expensive for cement clinker and blast furnace slag.

  By the way, the granulated blast furnace granulated slag obtained as a by-product as described above is generally stored in an outdoor yard, and often becomes wet due to rainwater or moisture in the air. However, since granulated blast furnace slag powder is an alkaline substance containing calcium as described above, when it is stored in a wet state, alkaline substances such as calcium eluted from itself are hydrated as the storage is prolonged. It becomes an initiator, invades the glassy structure constituting the slag, raises the pH, and at the same time causes a neutralization reaction with carbon dioxide in the air to produce a carbonate such as calcium carbonate. The deteriorated slag portion has already lost hydraulic properties, and when mixed with cement, it no longer works as an active ingredient for hardening. In addition, the deteriorated part is more easily pulverized than the slag sound part, and when the slag fine powder is managed with the same fineness, the sound part becomes virtually rougher than usual, and the hardening performance of the blast furnace cement is improved. There is a problem of lowering.

  In addition, blast furnace cement using slag containing a pulverized deteriorated part may cause member shrinkage due to the increased finely divided part in mortar and concrete after hardening, which is also a problem.

  Conventionally, blast furnace granulated slag that has deteriorated due to being left unattended for a long period of time is not used as a cement raw material because it cannot exhibit sufficient hydraulic properties, and after processing such as caking prevention has been performed It has only been used for civil engineering applications such as sand mats, embankments, or backfills, or for fine aggregate applications of concrete (see Patent Documents 1 and 2).

JP 54-71793 A JP 2002-179441 A

  The present invention relates to a method for reforming degraded blast furnace granulated slag, and a new application of the modified blast furnace granulated slag, specifically, a method for producing blast furnace cement using degraded blast furnace granulated slag. One purpose is to provide it.

As a result of earnest research to solve the above-mentioned problems, the present inventors have treated a deteriorated blast furnace slag with dilute sulfuric acid, thereby providing a blast furnace cement slag that can be suitably used as a raw material for blast furnace cement. As a result, the present invention was completed.
That is, the present invention provides a method for producing a modified blast furnace granulated slag, which is obtained by bringing a granulated blast furnace slag to which a deteriorated component is adhered into contact with dilute sulfuric acid. In addition, the present invention prepares a modified blast furnace granulated slag by contacting a granulated blast furnace slag having dilute sulfuric acid with calcium salt adhered to the particle surface, and produces a blast furnace cement using the modified blast furnace granulated slag. A method for producing a blast furnace cement is provided.

  According to the method for producing a blast furnace cement according to the present invention, the deteriorated blast furnace water is brought into contact with a granulated blast furnace slag having a deteriorated component adhered to the particle surface, that is, a deteriorated blast furnace granulated slag and dilute sulfuric acid. Deteriorated components adhering to the surface of the crushed slag particles react with dilute sulfuric acid to produce gypsum as a calcium salt, silica gel as a silicate, and alumina gel as an aluminum salt. And by using the modified blast furnace granulated slag newly produced by such gypsum, silica gel, and alumina gel as a cement raw material, the produced gypsum functions as a substitute for the gypsum component that has been added conventionally. The amount of gypsum to be added can be reduced. The produced silica gel or alumina gel reacts with the calcium salt eluted from the cement when the blast furnace cement is hydrated, and exhibits hydration activity.

  Therefore, by using the modified blast furnace granulated slag obtained by bringing dilute sulfuric acid into contact with the degraded blast furnace granulated slag as a blast furnace cement raw material, not only the main components of the slag but also the deterioration adhered to the blast furnace granulated slag The components also function as active components of the blast furnace cement, and all the components are effectively used in the blast furnace cement.

  As described above, according to the present invention, a new application of degraded blast furnace granulated slag, specifically, a method of producing blast furnace cement using degraded blast furnace granulated slag and reducing the amount of gypsum used is provided. Will be.

The graph which showed the measurement result of the mortar length change regarding the blast furnace cement of an example, a comparative example, and a reference example.

  The method for producing a blast furnace cement according to the present invention produces a modified blast furnace granulated slag by contacting so-called deteriorated blast furnace granulated slag and dilute sulfuric acid, and produces the blast furnace cement using the modified blast furnace granulated slag. To do.

Degraded blast furnace granulated slag usually means that when the blast furnace granulated slag is left outdoors, the granulated blast furnace slag wets with rain water or moisture in the air, and the calcium components and air eluted from the blast furnace granulated slag. It is in a state in which a deteriorated component adheres due to a neutralization reaction with carbon dioxide in the inside.
Examples of the deterioration component include calcium hydroxide (Ca (OH) ₂ formula amount 72), calcium carbonate (CaCO ₃ formula amount 100) and the like as crystalline ones, and aluminate as amorphous ones. Calcium hydrate (4CaO.Al ₂ O ₃ .13H ₂ O formula amount 560 as an average composition) and calcium silicate hydrate (3CaO.2SiO ₂ .4H ₂ O formula amount 360 as an average composition) Etc.

Degraded blast furnace granulated slag can be determined by measuring ignition loss (ig.loss). That is, the ignition loss of the blast furnace granulated slag that has not deteriorated increases in weight due to oxidation of the sulfide contained in the blast furnace granulated slag, and thus the ignition loss becomes a negative value. On the other hand, in the deteriorated slag, deteriorated components such as calcium hydroxide, calcium carbonate, calcium aluminate hydrate, and calcium silicate hydrate generated by deterioration are reduced by decarboxylation, decomposition of hydroxide, and dehydration. However, it occurs simultaneously with the increase due to sulfide oxidation, and the ignition loss is zero or a positive value.
The loss on ignition means the weight loss when the sample is heated for 30 minutes at 700 ± 25 ° C.

In addition, by performing thermogravimetric analysis of degraded blast furnace granulated slag, the amount of each deteriorated component (mass% with respect to the total amount A of degraded blast furnace granulated slag, hereinafter simply referred to as “%”) is measured. Can do. Specifically, the amount of calcium hydroxide (Ca (OH) ₂ ) production a (%) is the value obtained by multiplying the weight loss (%) at 450 ± 10 ° C by 72/18, and the production of calcium carbonate (CaCO ₃ ). the amount b (%) is weight loss in 700 ± 10 ℃ (%) to a value obtained by multiplying the 100/44, calcium aluminate hydrate production amount c (%) of _{(4CaO.Al 2 O 3 .13H 2 O} ) Is the value obtained by multiplying the weight loss (%) between 80 and 150 ° C. by 560/234, and the production amount d (%) of calcium silicate hydrate (3CaO.2SiO ₂ .4H ₂ O) is 150 to 400 It can be obtained as a value obtained by multiplying the weight loss (%) between ° C and 360/72 respectively.

  The deteriorated blast furnace granulated slag that can be treated in the present invention does not limit the content of the deteriorated component, but among them, the deteriorated component amount is preferably 5% or less. If the deteriorated component is 5% or less, the amount of gypsum produced by the contact between the deteriorated blast furnace granulated slag and dilute sulfuric acid can be set to a preferable range, and the obtained modified blast furnace granulated slag is used as a blast furnace. When manufacturing cement, there exists an effect that it becomes easy to satisfy the sulfur trioxide amount of the blast furnace cement prescribed | regulated to JISR5211.

  When dilute sulfuric acid is brought into contact with the degraded blast furnace granulated slag as described above, the deteriorated component and dilute sulfuric acid react to produce calcium salt as a calcium salt, silica gel as a silicate, and alumina gel as an aluminum salt. To do.

  When these components are blended as blast furnace cement, they are all active in the hydration hardening reaction of the cement component or blast furnace slag component, and can function as a part of the hydraulic material.

  The contact method between the deteriorated blast furnace granulated slag and dilute sulfuric acid is not particularly limited, and a conventionally known method can be appropriately employed as a solid-liquid contact method. When the deteriorated blast furnace granulated slag is a granular material, for example, a method of spraying dilute sulfuric acid on the granular material, a method of immersing the granular material in dilute sulfuric acid, and the like can be mentioned.

  The modified blast furnace granulated slag obtained by contact with dilute sulfuric acid is used by mixing with other cement compositions in the production process of blast furnace cement. Specifically, blast furnace cement can be produced by adding gypsum to the modified blast furnace granulated slag, pulverizing it to a predetermined fineness, and adding it to Portland cement. Moreover, a blast furnace cement can be manufactured by adding the refined granulated blast furnace granulated slag and gypsum, which are granular materials, to a non-ground cement clinker and finely pulverizing the powder to a predetermined fineness.

  The blending amount of the modified blast furnace granulated slag with respect to the cement is equivalent to the blending amount of the conventional blast furnace slag component according to the remaining amount B (%) of the undegraded slag component. What should I do? Specifically, if the production amount (%) of each deteriorated component is obtained as described above, the remaining slag amount B (%) is calculated from the deteriorated blast furnace granulated slag amount (100%), and the total amount of each deteriorated component. The amount is obtained by subtracting (a + b + c + d) (%) B (%) = 100− (a + b + c + d).

  That is, by determining the blending amount based on the residual slag component in the modified blast furnace granulated slag, the same blast furnace cement as conventional (for example, Class A, Class B, Class C) can be produced. It can be used for applications suitable for the properties.

The amount of gypsum added separately may be an amount obtained by subtracting the amount of gypsum contained in the reformed blast furnace granulated slag. Specifically, if the amount of each deteriorated component produced is determined as described above, the amount of gypsum C (%) produced when the deteriorated blast furnace granulated slag is brought into contact with dilute sulfuric acid is expressed by the following equation: Desired.
C (%) = a × (156/72) + b × (156/100) + c × (4 × 156/560) + d × (3 × 156/360)
Therefore, the amount of gypsum added separately can be reduced by the amount of gypsum derived from the modified blast furnace granulated slag (A × C (%)).

  The blast furnace cement obtained by the present invention can exhibit the same performance as conventional blast furnace cement. In addition, since silica gel and alumina gel that are not included in the conventional blast furnace cement are included, these silica gel and alumina gel react with calcium salts eluted from the cement when the blast furnace cement hydrates, Calcium silicate hydrate and calcium aluminate hydrate are produced, and the strength development is further enhanced.

The test was conducted using three types of blast furnace granulated slags A, B and C having different deterioration levels as shown in Table 1 below. As shown in Table 1, blast furnace granulated slag A is a healthy blast furnace granulated slag that has not deteriorated since the loss on ignition (Ig.loss) is a negative value. B and C are deteriorated blast furnace granulated slag because the loss on ignition is a positive value.

  Moreover, the thermogravimetric analysis about the said deterioration blast furnace granulated slag B and C was performed, and the production amount (%) for every deterioration component was measured. Furthermore, based on the measurement result, the amount of dihydrate gypsum produced that would be produced after the treatment with dilute sulfuric acid was calculated according to the calculation formula as described above. The results are shown in Table 2 below.

(Sulfuric acid treatment of degraded blast furnace granulated slag)
1 kg of granulated granulated blast furnace slag B and C is immersed in 1 liter of sulfuric acid with B of 0.82 mol / l and C of 0.035 mol / l for 10 minutes, then taken out and dried at 100 ° C. Quality blast furnace granulated slag B 'and C' were obtained. Thereafter, the modified blast furnace granulated slags B ′ and C ′ were pulverized, and the amount of gypsum produced by differential scanning calorimetry was determined. The results are also shown in Table 2.

  As shown in Table 2 above, the predicted value of the amount of gypsum production obtained by calculation from the amount of degradation component produced, and the amount of gypsum produced by actual treatment with dilute sulfuric acid, It was found that there was a general agreement.

(Production of blast furnace cement)
Blast furnace cement was prepared using a total of five types of slag, namely, healthy blast furnace granulated slag A, degraded blast furnace granulated slags B and C, and modified blast furnace granulated slags B ′ and C ′.

(Reference example)
After pulverizing healthy granulated blast furnace slag A to a Blaine specific surface area of 4400 ± 100 cm ² / g, 3.83 kg of the slag A, 172 g of dihydrate gypsum and 6 kg of ordinary Portland cement were mixed to prepare a blast furnace cement.

(Comparative Example 1)
A blast furnace cement was produced in the same manner as the reference example except that the deteriorated blast furnace granulated slag B was replaced with 3.83 kg of the degraded blast furnace granulated slag A.

(Comparative Example 2)
A blast furnace cement was produced in the same manner as in the reference example except that the deteriorated blast furnace granulated slag C was replaced with 3.83 kg of deteriorated blast furnace granulated slag C.

Example 1
The modified blast furnace granulated slag B ′ was pulverized to a Blaine specific surface area of 4400 ± 100 cm ² / g, and then 3.83 kg of the slag B ′, 123 g of dihydrated gypsum and 6 kg of ordinary Portland cement were mixed to prepare a blast furnace cement.

(Example 2)
After the modified blast furnace granulated slag B ′ was pulverized to a Blaine specific surface area of 4400 ± 100 cm ² / g, 3.83 kg of the slag B ′, 152 g of dihydrate gypsum and 6 kg of ordinary Portland cement were mixed to prepare a blast furnace cement.

The composition of the above Examples, Comparative Examples and Reference Examples is shown in Table 3 below.

(Evaluation)
Using each of the produced blast furnace cements, a mortar was molded according to JIS R 5202, the mortar strength at the age of 3, 7 and 28 days was measured, and the change in length was measured according to JIS A 1129. The results are shown in Tables 4 and 5 below and FIG.

As shown in Table 4, in Examples 1 and 2 using the modified blast furnace granulated slag, it is recognized that the compressive strength equivalent to that of the reference example using the sound blast furnace granulated slag is obtained.
Moreover, as shown in Table 5 and FIG. 1, in Examples 1 and 2 using the modified blast furnace granulated slag, the drying shrinkage is reduced to the same level as the reference example using the sound blast furnace granulated slag. It is recognized that

  Moreover, as shown in Table 3, in Examples 1 and 2, the amount of gypsum added separately was reduced by 28% and 12%, respectively, and the effect that blast furnace cement can be produced while reducing the amount of gypsum used. There is also.

Claims (3)

  A method for producing a reformed blast furnace granulated slag, which is obtained by contacting a granulated blast furnace slag with a deteriorated component and dilute sulfuric acid.   A modified blast furnace granulated slag is prepared by contacting a blast furnace granulated slag with a deteriorated component and dilute sulfuric acid, and a blast furnace cement is produced using the modified blast furnace granulated slag. Production method.   The blast furnace cement according to claim 1, wherein the deterioration component includes at least one selected from the group consisting of calcium hydroxide, calcium carbonate, calcium aluminate hydrate, and calcium silicate hydrate. Manufacturing method.

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