JP6919264B2 - Cement composition and its manufacturing method - Google Patents

Description

The present invention contains cement clinker, gypsum, a mixture, and dust, and contains at least one of limestone and blast furnace slag as the mixture, and the total amount of limestone and blast furnace slag is more than 40% by mass and 70 mass. Percentage or less of the cement composition and the method for producing the same.

The cement industry is an industry that emits carbon dioxide, which is a greenhouse gas, and reducing its emissions is an important issue. In the cement industry, when the raw material is fired in the process of manufacturing cement clinker, which is an intermediate product of cement, carbon dioxide is generated by the chemical reaction of the raw material limestone, so carbon dioxide is emitted as long as the cement clinker is manufactured. ..

Ordinary Portland cement contains about 95% by mass of clinker in the cement composition. On the other hand, since mixed cement uses a mixed material such as blast furnace slag and coal ash (fly ash), the ratio of clinker contained in the cement composition can be reduced, which contributes to reduction of carbon dioxide emissions. .. Patent Documents 1 to 4 disclose cement compositions containing blast furnace slag. Patent Documents 3 and 4 disclose a cement composition using blast furnace slag and chlorine bypass dust in combination and a method for producing the same, and Patent Document 5 discloses a cement composition using blast furnace slag and desalted dust in combination and a method for producing the same. Is disclosed.

Japanese Unexamined Patent Publication No. 2004-137318 JP-A-2002-265241 Japanese Unexamined Patent Publication No. 10-218657 Japanese Unexamined Patent Publication No. 2016-5997 Japanese Unexamined Patent Publication No. 2009-62260

INDUSTRIAL APPLICABILITY The present invention can effectively utilize dust that has been a waste in the past, can sufficiently reduce the amount of carbon dioxide generated in the manufacturing process, and develop the strength of a hardened body such as mortar or concrete as compared with the conventional mixed cement. An object of the present invention is to provide a cement composition capable of maintaining or improving properties (compressive strength) and a method for producing the same.

As a result of diligent studies to achieve the above problems, the present inventors have compared with conventional mixed cement by using a specific dust or a specific combination of dust in the process of producing a cement composition. We have found that a cement composition that maintains or improves the strength development of the cured product can be obtained, and has completed the present invention.

That is, the cement composition according to the present invention contains cement clinker, gypsum, a mixing material, and dust, and contains at least one of limestone and blast furnace slag as the mixing material, and limestone based on the total mass of the cement composition. And the total amount of blast furnace slag is more than 40% by mass and 70% by mass or less, and the dust includes one selected from the group consisting of the following dusts 1 to 6.
・ Dust 1: Electrostatic dust ・ Dust 2: Desalted dust ・ Dust 3: Mixed dust of electrostatically collected dust and chlorine bypass dust ・ Dust 4: Mixed dust of electrostatically collected dust and desalted dust ・ Dust 5 : Mixed dust of chlorine bypass dust and desalted dust ・ Dust 6: Mixed dust of electrostatic collection dust, chlorine bypass dust and desalted dust

The present invention provides a method for producing a cement composition. That is, this production method includes a step of obtaining a cement composition by mixing cement clinker, gypsum, a mixture, and dust, and the cement composition contains at least one of limestone and blast furnace slag as a mixture. Including, the total amount of limestone and blast furnace slag is more than 40% by mass and 70% by mass or less based on the total mass of the cement composition, and includes one selected from the group consisting of dusts 1 to 6 as dust.
・ Dust 1: Electrostatic dust ・ Dust 2: Desalted dust ・ Dust 3: Mixed dust of electrostatically collected dust and chlorine bypass dust ・ Dust 4: Mixed dust of electrostatically collected dust and desalted dust ・ Dust 5 : Mixed dust of chlorine bypass dust and desalted dust ・ Dust 6: Mixed dust of electrostatic collection dust, chlorine bypass dust and desalted dust

According to the cement composition, the electrostatic precipitator dust, chlorine bypass dust, and desalted dust contained in the dusts 1 to 6 can be effectively used. Further, according to the study by the present inventors, sufficient strength development can be obtained even if the ratio of any one of the above dusts 1 to 6 in the cement composition is sufficiently increased. Therefore, according to the present invention, the ratio of clinker contained in the cement composition can be reduced, whereby the amount of carbon dioxide generated during the production of the cement composition per unit mass can be sufficiently reduced.

Specific examples of electrostatic precipitators, chlorine bypass dusts and desalted dusts include those in which the content of a specific oxide and the amount of chloride ions are in the following ranges.
・ Electrostatic dust collection (mass standard of electrostatic precipitator)
SiO ₂ content: 5 to 20% by mass
Al ₂ O ₃ content: 2-8% by mass
Fe ₂ O ₃ content: 0.1 to 5% by mass
CaO content: 30-50% by mass
Chloride ion amount: 0.05 to 2% by mass
・ Chlorine bypass dust (mass standard of chlorine bypass dust)
SiO ₂ content: 1 to 30% by mass
Al ₂ O ₃ content: 0.1 to 10% by mass
Fe ₂ O ₃ content: 0.1 to 5% by mass
CaO content: 1-65% by mass
Chloride ion amount: 4-35% by mass
・ Desalted dust (mass standard of desalted dust)
SiO ₂ content: 5 to 30% by mass
Al ₂ O ₃ content: 1 to 15% by mass
Fe ₂ O ₃ content: 0.1 to 5% by mass
CaO content: 15-65% by mass
Chloride ion amount: 0.1 to 2% by mass

From the viewpoint of strength development, the cement composition contains 0.1 to 20% by mass of electrostatic precipitators, 0.05 to 5% by mass of chlorine bypass dust, and / or, based on the total mass of the cement composition. Alternatively, it preferably contains 0.1 to 20% by mass of desalted dust. From the same viewpoint, the total amount of electrostatic precipitator dust, chlorine bypass dust, and desalted dust in the cement composition is preferably 0.1 to 20% by mass based on the total mass of the cement composition.

In the present invention, the amount of chloride ion preferably satisfies the following conditions from the viewpoint of strength development.
-The amount of chloride ions is 0.01 to 0.2% by mass based on the total mass of the cement composition.
-The amount of chloride ions brought into the cement composition from dust is 0.01 to 0.2% by mass based on the total mass of the cement composition.

According to the present invention, it is possible to effectively utilize dust that has been a waste in the past, _{and while reducing carbon dioxide (CO 2} ) emissions in the manufacturing process, the strength of the cured product is exhibited as compared with the conventional mixed cement. A cement composition capable of maintaining or improving properties and a method for producing the same are provided.

FIG. 1 is a diagram showing the relationship between the amount of clinker and the compressive strength of mortar in the cement composition in Examples, Comparative Examples and Reference Examples.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments.

<Cement composition>
The cement composition according to the present embodiment contains cement clinker, gypsum, a mixing material, and dust, contains at least one of limestone and blast furnace slag as the mixing material, and is a group consisting of the following dusts 1 to 6 as dust. Including one selected from.
・ Dust 1: Electrostatic dust ・ Dust 2: Desalted dust ・ Dust 3: Mixed dust of electrostatically collected dust and chlorine bypass dust ・ Dust 4: Mixed dust of electrostatically collected dust and desalted dust ・ Dust 5 : Mixed dust of chlorine bypass dust and desalted dust ・ Dust 6: Mixed dust of electrostatic collection dust, chlorine bypass dust and desalted dust

The mineral composition of cement clinker is as follows: C ₃ S content is 45 to 70% by mass, C ₂ S content is 5 to 25% by mass, C ₃ A content is 6 to 15% by mass, and C ₄ AF is contained. The amount is preferably 7 to 15% by mass. The mineral composition of the cement clinker is more preferably C ₃ S content of 48 to 65% by mass, C ₂ S content of 10 to 25% by mass, C ₃ A content of 8 to 13% by mass and C ₄ AF content. The amount is 8 to 12% by mass, more preferably the C ₃ S content is 50 to 64% by mass, the C ₂ S content is 11 to 20% by mass, the C ₃ A content is 9 to 12% by mass and C. ₄ AF content is 8 to 11% by mass, particularly preferably C ₃ S content is 53 to 60% by mass, C ₂ S content is 11 to 19% by mass, and C ₃ A content is 9 to 11% by mass. % And C ₄ AF content is 8-10% by weight. The cement clinker can be manufactured by using an existing cement manufacturing facility such as an SP method (multi-stage cyclone preheating method) or an NSP method (multi-stage cyclone preheating method equipped with a calcining furnace).

_{Here, the C 3} S amount, C ₂ S amount, C ₃ A amount, and C ₄ AF amount calculated by the Borg formula are calculated by the following formulas [1], [2], [3], and [4], respectively. The value.
C ₃ S amount (mass%) = 4.07 x CaO (%) -7.60 x SiO ₂ (%) -6.72 x Al ₂ O ₃ (%) -1.43 x Fe ₂ O ₃ ( %) -2.85 x SO ₃ (%) ... [1]
C ₂ S amount (mass%) = 2.87 × SiO ₂ (%) −0.754 × C ₃ S (%)… [2]
-C ₃ A amount (mass%) = 2.65 x Al ₂ O ₃ (%) -1.69 x Fe ₂ O ₃ (%) ... [3]
・ C ₄ AF amount = 3.04 × Fe ₂ O ₃ (%)… [4]

The chloride ion content of the cement composition is preferably 0.01 to 0.2% by mass, more preferably 0.015 to 0.16% by mass, and further preferably 0.02 to 0.12% by mass. %, Especially preferably 0.025 to 0.085% by mass. The amount of chloride ions in the cement composition can be measured by the method of JIS R 5202: 1999 "Chemical analysis method of cement".

The brain specific surface area of the cement composition is preferably 2800 to 8500 cm ² / g, more preferably 3000 to 8000 cm ² / g, ^{still more preferably 3500 to 7500 cm 2} / g, and particularly preferably 4000 to 7000 cm. ^{It is 2} / g. When the brain specific surface area is within the above range, mortar or concrete having excellent strength development can be produced.

The amount of cement clinker contained in the cement composition is preferably 8 to 57% by mass, more preferably 8 to 40% by mass, and further preferably 10 to 35% by mass based on the total mass of the cement composition. Yes, particularly preferably 10 to 30% by mass. As long as the amount of cement clinker contained in the cement composition is within the above range, even if the cement composition contains the above dust, it exhibits strength development equal to or higher than that of the cement composition not containing the dust. Cheap.

As the gypsum, it is preferable to use one that satisfies the quality specified in JIS R 9151: 1979 "Natural Anhydrite for Cement", and specifically, dihydrate gypsum, semi-hydrated gypsum and insoluble anhydrous gypsum are preferably used. Be done. These may be used alone or in combination of two or more.

The _{amount of SO 3} contained in the cement composition is preferably 1.7 to 2.9% by mass, more preferably 1.9 to 2.7% by mass, and further, based on the total mass of the cement composition. It is preferably 2.1 to 2.5% by mass. When SO ₃ content of the cement composition is within the above range, it is possible to maintain or improve the strength development. The SO ₃ content of the cement composition (ratio (%) to the total mass of the cement composition) can be measured according to JIS R 5202: 1999 “Cement Chemical Analysis Method”.

The cement composition according to the present embodiment contains at least one of limestone and blast furnace slag as a mixed material, and the total amount of limestone and blast furnace slag is more than 40% by mass and 70% by mass based on the total mass of the cement composition. It is more preferably 45 to 70% by mass, further preferably 50 to 70% by mass, still more preferably 55 to 70% by mass. When these total amounts exceed 40% by mass, the ratio of clinker contained in the cement composition can be reduced, and the amount of carbon dioxide generated by the production of the cement composition per unit mass can be sufficiently reduced. On the other hand, when the total amount thereof is 70% by mass or less, the strength development of the cured product can be maintained or improved as compared with the conventional mixed cement.

As the limestone, a limestone containing 90% or more of _{CaCO 3} specified in JIS R 5210: 2009 "Portland cement" may be used. The particle size of the limestone is preferably 50 mm or less, more preferably 30 mm or less, still more preferably 20 mm or less. As the limestone, those having a particle size outside the above range, that is, those having a low degree of powder (large particle size) may be used or used in combination.

The amount of limestone contained in the cement composition is preferably 1 to 8% by mass, more preferably 2 to 8% by mass, and further preferably 2 to 6% by mass based on the total mass of the cement composition. .. When the amount of limestone in the cement composition is within the above range, the strength development can be maintained or improved.

As the blast furnace slag, the blast furnace slag specified in JIS R 5211: 2003 “Blast furnace cement” may be used. The particle size of the blast furnace slag is preferably 5 mm or less, more preferably 3 mm or less, and further preferably 2 mm or less. As the blast furnace slag, slag having a particle size outside the above range, that is, slag having a low degree of powder (large particle size) may be used or used in combination.

The amount of blast furnace slag in the cement composition is preferably 38 to 69% by mass, more preferably 45 to 69% by mass, still more preferably 50 to 68% by mass, based on the total mass of the cement composition. Particularly preferably, it is 55 to 68% by mass. When the amount of blast furnace slag in the cement composition is within the above range, the strength development can be maintained or improved.

As the blast furnace slag, it is preferable to use a blast furnace slag having a basicity in a predetermined range. There are a plurality of calculation methods for the basicity of blast furnace slag, and for example, the following calculation formula is known. From the viewpoint of strength development, the basicity (JIS) of the blast furnace slag is preferably 1.3 to 2.3, more preferably 1.6 to 2.1, and the basicity of the blast furnace slag (TiO ₂ conversion). ) Is preferably 1.2 to 2.3, more preferably 1.5 to 2.1, and the basicity (Bm) of the blast furnace slag is preferably 1.05 to 2.00, more preferably. Is 1.35 to 1.80.
-Basicity (JIS) = (CaO + MgO + Al ₂ O ₃ ) / SiO ₂
-Basicity (TIO ₂ conversion) = (CaO + MgO + Al ₂ O ₃ ) / SiO _2- (0.13 x TiO ₂ )
-Basicity (Bm) = (CaO + MgO + Al ₂ O ₃ ) / SiO _2- (0.13 x TiO ₂ ) -MnO

As described above, the cement composition according to the present embodiment contains as dust one selected from the group consisting of the following dusts 1 to 6.
・ Dust 1: Electrostatic dust ・ Dust 2: Desalted dust ・ Dust 3: Mixed dust of electrostatically collected dust and chlorine bypass dust ・ Dust 4: Mixed dust of electrostatically collected dust and desalted dust ・ Dust 5 : Mixed dust of chlorine bypass dust and desalted dust ・ Dust 6: Mixed dust of electrostatic collection dust, chlorine bypass dust and desalted dust

The electrostatic precipitator is dust collected by the electrostatic precipitator (EP: Electrostatic Precipitator), and the dust contained in the cement kiln exhaust gas or the residual heat of the cement kiln exhaust gas is used in the raw material mill and the raw material dryer. It means the dust contained in the later exhaust gas. Electrostatic precipitator dust (hereinafter, referred to as. "EP dust") are based on the weight of the EP dust, the SiO ₂ 5 to 20 wt%, the _Al 2 _{O 3} 2 to 8 wt%, a _Fe 2 _{O 3} 0. It may contain 1 to 5% by mass and 30 to 50% by mass of CaO. The amount of chloride ion of EP dust is preferably 0.05 to 2% by mass, more preferably 0.1 to 1.5% by mass, still more preferably 0.1 to 0, based on the mass of EP dust. It is 0.6% by mass.

The EP dust may be fine powder (average particle size of about 1 to 10 μm) containing _{calcium carbonate (CaCO 3) as a main component.}

When EP dust is used as the dust (dusts 1, 3, 4, 6 above), the amount of EP dust in the cement composition is preferably 0.1 to 30% by mass based on the total mass of the cement composition. It is more preferably 0.1 to 25% by mass, further preferably 0.5 to 25% by mass, even more preferably 0.5 to 20% by mass, and particularly preferably 1 to 20% by mass. ..

Chlorine bypass dust means dust generated from chlorine bypass extracted from the NSP (New Suspension Preheater) tower of a cement kiln. Chlorine bypass dust contains 1 to 30% by mass of _{SiO 2} , 0.1 to 10% by mass of _{Al 2} O ₃ , 0.1 to 5% by mass of _{Fe 2} O ₃ , and CaO based on the mass of chlorine bypass dust. It may contain 1 to 65% by mass. The chloride ion amount of the chlorine bypass dust is preferably 4 to 35% by mass, more preferably 5 to 33% by mass, and further preferably 6 to 31% by mass based on the mass of the chlorine bypass dust.

When chlorine bypass dust is used as the dust (dusts 3, 5 and 6 above), the amount of chlorine bypass dust in the cement composition is preferably 0.05 to 5% by mass based on the total mass of the cement composition. It is more preferably 0.1 to 3% by mass, further preferably 0.1 to 2% by mass, and particularly preferably 0.1 to 1% by mass.

Desalted dust means a water-washed residue obtained by washing chlorine bypass dust with water and then solid-liquid separation by filtration treatment. If the desalted dust has a large amount of water, it may be dried using the exhaust gas from the kiln. Desalting dust is based on the mass of desalted dust, SiO ₂ is 5 to 30% by mass, Al ₂ O ₃ is 1 to 15% by mass, Fe ₂ O ₃ is 0.1 to 5% by mass, and CaO is 15 to 15% by mass. It may contain 65% by mass. The amount of chloride ions in the desalted dust is 0.1 to 2.0% by mass, more preferably 0.3 to 1.8% by mass, still more preferably 0.5 to 1. It is 6% by mass.

When desalted dust is used as the dust (dusts 2, 4 to 6 above), the amount of desalted dust in the cement composition is preferably 0.1 to 20% by mass based on the total mass of the cement composition. It is more preferably 0.3 to 18% by mass, further preferably 0.5 to 15% by mass, and particularly preferably 0.5 to 8% by mass.

The total amount of EP dust, chlorine bypass dust and desalted dust in the cement composition is preferably 0.1 to 30% by mass, more preferably 0.1 to 25% by mass, based on the total mass of the cement composition. Yes, more preferably 0.5 to 20% by mass, and particularly preferably 1.0 to 15% by mass. When the amount of dust (the total amount of EP dust, chlorine bypass dust and desalted dust) is within the above range, the strength development can be maintained or increased. The mechanism by which the strength development of the hardened product using the cement composition containing limestone and blast furnace slag is increased by adding the above dust to the cement composition is not clear, but the main cause is the free lime contained in each dust. It is considered that (f. CaO) acts as a stimulant for cement or blast furnace slag and the hydration reaction gradually proceeds, or the strength development is increased by the action of chloride ions or the filler effect of dust. Be done.

The total amount of chloride ions brought into the cement composition from EP dust, chlorine bypass dust and desalted dust (based on the total mass of the cement composition) is preferably 0.01 to 0.2% by mass, more preferably. Is 0.015 to 0.16% by mass, more preferably 0.02 to 0.12% by mass, and particularly preferably 0.02 to 0.085% by mass.

<Manufacturing method of cement composition>
The method for producing the cement composition is by mixing cement clinker, gypsum, a specific mixture (at least one of limestone and blast furnace slag), and specific dust (any one of dusts 1 to 6). Includes the step of obtaining a cement composition. For these mixing, for example, a ball mill may be used, and more specifically, the ball mill may be used for pulverizing and mixing so as to obtain a desired brain specific surface area. The order in which each component is charged into the ball mill is not particularly limited, and the cement composition may be obtained by adding specific dust to the cement composition previously pulverized using the ball mill. Other types of crushers may be used instead of the ball mill.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

Table 1 shows the ratios, mineral composition and chemical composition of the cement clinker used. These data were obtained by the above-mentioned Borg formula or the like from the analysis results quantified according to JIS R 5202: 1999 “Chemical analysis method for cement”. In addition, among the chemical components, f. CaO was measured according to JCASI-01-1997 "Method for quantifying free calcium oxide".

Table 2 shows the quality (chemical composition) of the gypsum used (exhausted dihydrate gypsum). The chemical composition of gypsum was measured according to JIS R 9101: 1995 "Chemical analysis method of gypsum".

Table 3 shows the quality (chemical composition) of the limestone used. The chemical composition of limestone was measured according to JIS M 8850: 1994 "Limestone analysis method".

The blast furnace slag used was crushed to about 5 mm or less by a crusher. Among the blast furnace slag qualities used, the chemical composition is shown in Table 4, and the basicity, brain specific surface area and activity index are shown in Table 5. The chemical composition of the blast furnace slag was quantified according to JIS R 5202: 1999 “Chemical analysis method for cement”. The basicity of the blast furnace slag was calculated by a calculation formula. The activity index was measured according to JIS A 6206: 2013 “Blast furnace slag fine powder for concrete”.
-Basicity (JIS) = (CaO + MgO + Al ₂ O ₃ ) / SiO ₂
-Basicity (TIO ₂ conversion) = (CaO + MgO + Al ₂ O ₃ ) / SiO _2- (0.13 x TiO ₂ )
-Basicity (Bm) = (CaO + MgO + Al ₂ O ₃ ) / SiO _2- (0.13 x TiO ₂ ) -MnO

The chemical composition of the EP dust used is shown in Table 6, and the particle size distribution and average particle size are shown in Table 7. The chemical composition of EP dust (SiO ₂ to SO _{3 in} Table 6 and the amount of chloride ion (Cl)) was measured according to JIS R 5202: 1999 “Cement Chemical Analysis Method”. f. CaO was measured according to JIS M 8853: 1998 "Chemical analysis method for aluminosilicate raw materials for ceramics". The particle size distribution and average particle size were measured by mixing and stirring EP dust with ethanol and using a laser particle size analyzer LMS-30 manufactured by Seishin Enterprise Co., Ltd.

The chemical composition of the chlorine bypass dust used is shown in Table 8, and the particle size distribution and average particle size are shown in Table 9. The chemical components of chlorine bypass dust (SiO ₂ to SO _{3 in} Table 8 and f. CaO) were measured according to JIS M 8853: 1998 "Chemical analysis method for aluminosilicate raw materials for ceramics". The amount of chloride ion (Cl) was measured according to JIS R 5202: 1999 “Chemical analysis method for cement”. The particle size distribution and average particle size were measured by mixing and stirring chlorine bypass dust with ethanol and using a laser particle size analyzer LMS-30 manufactured by Seishin Enterprise Co., Ltd.

The chemical composition of the desalted dust used is shown in Table 10. The desalted dust used was crushed with a disc mill for 1 minute. The chemical components of the desalted dust (SiO ₂ to SO _{3 in} Table 10 and f. CaO) were measured according to JIS M 8853: 1998 “Chemical analysis method for aluminosilicate raw materials for ceramics”. The amount of chloride ion (Cl) was measured according to JIS R 5202: 1999 “Chemical analysis method for cement”.

[Preparation of cement composition]
Table 11 shows the composition of the cement composition (based on the total mass of the cement composition). As the first step, each material (cement clinker, waste desulfurization dihydrate gypsum (smoke exhaust desulfurization dihydrate gypsum), limestone and blast furnace slag) is coarsely crushed to a diameter of 5 mm or less, and the brain specific surface area is 4500 ± 100 cm ^{2 with a test ball mill.} The mixture was pulverized to / g to obtain a cement composition before adding each dust. As the second step, a predetermined amount of dust was added to the cement composition obtained in the first step, and the mixture was mixed with a locking mixer for 20 minutes to obtain a cement composition having the formulation shown in Table 11.

Table 12 shows the physical characteristics and chemical components of the obtained cement composition. Further, FIG. 1 shows the relationship between the amount of clinker and the compressive strength of mortar in the cement compositions in Reference Examples 1, Comparative Examples 1 to 4, and Examples 1 to 9.

The "brain specific surface area (before and after dust addition)" in Table 12 was measured according to JIS R 5201: 1997 "Physical test method for cement".

The "f. CaO amount" of the cement composition in Table 12 was measured according to JCAS I-01: 1997 "Method for quantifying free calcium oxide in cement" (based on the total mass of the cement composition). The "chloride ion amount" of the cement composition in Table 12 was measured according to JIS R 5202: 1999 "Chemical analysis method of cement".

The "water amount" in Table 12 is the amount of water (standard softness water amount) required to keep the softness (softness) of the cement paste constant, and the larger the amount, the worse the fluidity of the cement. do. The measuring method is as follows: 500 g of the cement composition is put into a kneading pot, water is added and kneaded, the cement paste is put into a container, the surface is smoothed, the standard rod is lowered, and 30 seconds later, the standard rod is measured. The distance between the tip and the bottom plate is measured, and the amount of water at which this is 6 ± 1 mm (standard softness) is measured and used as the standard soft water amount.

“Condensation (starting and ending)” and “mortar compressive strength” (hereinafter referred to as “compressive strength”) in Table 12 are based on JIS R 5201: 1997 “Cement” using the obtained cement composition. It was measured according to "Physical test method". For example, when the "first train (h: m)" in Reference Example 1 in Table 12 is "2:27", it means that the first train time of condensation is 2 hours and 27 minutes, and the "end train (h: m)". However, "3:27" means that the final time of condensation is 3 hours and 27 minutes.

“Clinker reduction rate” in Table 12 indicates the reduction rate from Reference Example 1 corresponding to ordinary Portland cement. For example, from Table 11, the amount of clinker in Reference Example 1 is 91.95% by mass, and the amount of clinker in Comparative Example 1 is 25.27%. From these values, the clinker reduction rate of Comparative Example 1 is calculated to be 72.52% (= (91.95-25.27) /91.95 × 100).

The amount of carbon dioxide generated in cement production is generally indicated by the sum of non-energy (limestone decarboxylation) origin, fossil energy origin, (fossil origin) combustible origin such as waste, and reduction amount due to no incineration. _{The "approximate value of CO 2} reduction amount" in Table 12 is calculated from Reference Example 1 only for the reduction amount of non-energy-derived carbon dioxide generation amount by reducing the amount of clinker used. Here, the amount of non-energy-derived carbon dioxide in Reference Example 1 was set to 468.5 g / kg described in the inventory data list by cement type announced by the Cement Association, and this was calculated by multiplying this by the clinker reduction rate. For example, the amount of carbon dioxide reduced in Comparative Example 1 is calculated to be 339.7 g / kg (= 468.5 × 72.52 / 100).

Reference Example 1 shown in Table 12 and FIG. 1 is a formulation of ordinary Portland cement (cement clinker 91.95%, mixture 5% [limestone: slag = 4: 1], brain specific surface area 3250 cm ² / g).

As shown in Comparative Example 1 (cement clinker 25.27%, mixture 70% [limestone: slag = 2:68], brain specific surface area 4460 cm ² / g), carbon dioxide generation in cement production is higher than that in Reference Example 1. When the amount of the mixed material added is increased by 65% in order to reduce the amount, the amount of carbon dioxide generated can be reduced as compared with Reference Example 1, but the compressive strength at each material age is reduced.

As shown in Comparative Example 2 (cement clinker 22.74%, mixed material 72.5% (limestone: slag = 2.5: 70), the amount of the mixed material added while maintaining the brain specific surface area of Comparative Example 1 as it is. When limestone was increased by 0.5% and blast furnace slag was increased by 2%, the compressive strength at each material age was lower than that of Comparative Example 1.

As shown in Comparative Example 3 (cement clinker 10.29%, mixed material 85% (limestone: slag = 2: 83), the blast furnace slag of the mixed material addition amount was used while maintaining the brain specific surface area of Comparative Example 1. In the case of an increase of 15%, the compressive strength at each material age is lower than that of Comparative Examples 1 and 2.

Here, as shown in Comparative Example 4 (0.141% by mass of chlorine bypass dust was added to Comparative Example 1), by adding chlorine bypass dust, the compressive strength of each material age was compared with that of Comparative Example 1. Is rising. That is, it is known that the addition of chlorine bypass dust is effective as a method for suppressing a decrease in the compressive strength of the mixed cement shown in Comparative Examples 1 to 3 and improving the strength development.

In this example, Examples 1 to 9 in which all or a part of the chlorine bypass dust in Comparative Example 4 is replaced with EP dust and / or desalted dust and dusts 1 to 6 are added are referred to the above Comparative Example. The effect of each dust on the compressive strength of the mixed cement was evaluated in comparison with 1 to 3. Here, the amount of each dust added in Examples 1 to 9 was adjusted so that the chloride ion in the cement composition was about 0.03 to 0.04% by mass. The effects of each dust added on the compressive strength obtained by the evaluation are described below.

The straight lines connecting Comparative Examples 1 to 3 in FIG. 1 indicate a decrease in strength development due to a decrease in the amount of clinker in the cement composition due to an increase in blast furnace slag. Examples 1 to 9 to which any of dusts 1 to 6 was added are plotted above the straight line connecting Comparative Examples 1 to 3 at each age, and in the cement composition in which the amount of clinker was reduced by adding dust, It shows that the compressive strength at each material age is higher than when no dust is added. That is, it was confirmed that dusts 1 to 6 are also effective in improving the strength development, similar to the effect of adding chlorine bypass dust shown in Comparative Example 4.

Although the mechanism for maintaining or improving the strength development by adding various kinds of dust is not clear, chloride ions in the dust or f. It is considered that CaO became a stimulant for cement or blast furnace slag and the hydration reaction gradually proceeded, or due to the filler effect of dust.

Further, as shown in Table 12, the clinker reduction rate from Reference Example 1 in Examples 1 to 9 and the _{estimated CO 2} reduction amount achieved by the clinker reduction rate both exceed Comparative Example 4. That is, in Examples 1 to 9, a part or all of the chlorine bypass dust in Comparative Example 4 is dust 1 to 6 using EP dust or desalted dust having a lower chloride ion amount than chlorine bypass dust. _{, CO 2} can be reduced more than in Comparative Example 4, and each has sufficient strength development as described above.

From the above results, according to the cement composition according to the present embodiment, wastes such as chlorine bypass dust, desalted dust, and EP dust can be effectively used, and the _{amount of CO 2} generated in the manufacturing process can be sufficiently reduced. , It is possible to maintain or improve the strength development as compared with the conventional mixed cement.

Claims (8)

A cement composition containing cement clinker, gypsum, a mixture, and dust.
The mixture contains at least one of limestone and blast furnace slag, and the total amount of limestone and blast furnace slag is more than 40% by mass and 70% by mass or less based on the total mass of the cement composition.
Look including the one selected from the group consisting of dust 1-6 as the dust, based on the total mass of the cement composition, and electrostatic precipitator dust and chlorine bypass dust, is the total amount of the desalination dust 1 .0 to 30% by mass,
Based on the total mass of the cement composition, 0.1 to 20% by mass of the electrostatic precipitator, 0.05 to 5% by mass of the chlorine bypass dust and / or 0.1 to 20% by mass of the desalting. A cement composition containing dust.
・ Dust 1: Electrostatic dust ・ Dust 2: Desalted dust ・ Dust 3: Mixed dust of electrostatically collected dust and chlorine bypass dust ・ Dust 4: Mixed dust of electrostatically collected dust and desalted dust ・ Dust 5 : Mixed dust of chlorine bypass dust and desalted dust ・ Dust 6: Mixed dust of electrostatic collection dust, chlorine bypass dust and desalted dust The cement composition according to claim 1, wherein the amount of chloride ions is 0.01 to 0.2% by mass based on the total mass of the cement composition. The cement composition according to claim 1 or 2, wherein the total amount of chloride ions brought into the cement composition from the dust is 0.01 to 0.2% by mass based on the total mass of the cement composition. _{The electrostatic precipitator has a SiO 2} content of 5 to 20 mass%, an Al ₂ O ₃ content of 2 to 8 mass%, and a Fe ₂ O ₃ content based on the mass of the electrostatic precipitator. The amount is 0.1 to 5% by mass, the CaO content is 30 to 50% by mass, and the chloride ion content is 0.05 to 2% by mass, according to any one of claims 1 to 3. The cement composition described. _{The chlorine bypass dust has a SiO 2} content of 1 to 30% by mass, an Al ₂ O ₃ content of 0.1 to 10% by mass, and a Fe ₂ O ₃ content based on the mass of the chlorine bypass dust. The invention according to any one of claims 1 to 4, wherein the amount is 0.1 to 5% by mass, the CaO content is 1 to 65% by mass, and the chloride ion content is 4 to 35% by mass. Cement composition. _{The desalted dust has a SiO 2} content of 5 to 30 mass%, an Al ₂ O ₃ content of 1 to 15 mass%, and a Fe ₂ O ₃ content based on the mass of the desalted dust. 10. Cement composition. Any of claims 1 to 6, wherein the total amount of the electrostatic precipitator dust, the chlorine bypass dust, and the desalted dust is 0.1 to 20 mass% based on the total mass of the cement composition. The cement composition according to item 1. A method for producing a cement composition, which comprises a step of obtaining a cement composition by mixing a cement clinker, gypsum, a mixing material, and dust.
The cement composition contains at least one of limestone and blast furnace slag as the mixture, and the total amount of limestone and blast furnace slag is more than 40% by mass and 70% by mass or less based on the total mass of the cement composition. ,
Look including the one selected from the group consisting of dust 1-6 as the dust, based on the total mass of the cement composition, and electrostatic precipitator dust and chlorine bypass dust, is the total amount of the desalination dust 1 .0 to 30% by mass,
The cement composition is 0.1 to 20% by mass of the electrostatic precipitator, 0.05 to 5% by mass of the chlorine bypass dust and / or 0.1 to 20% by mass based on the total mass of the cement composition. A method for producing a cement composition, which comprises mass% of the desalted dust.
・ Dust 1: Electrostatic dust ・ Dust 2: Desalted dust ・ Dust 3: Mixed dust of electrostatically collected dust and chlorine bypass dust ・ Dust 4: Mixed dust of electrostatically collected dust and desalted dust ・ Dust 5 : Mixed dust of chlorine bypass dust and desalted dust ・ Dust 6: Mixed dust of electrostatic collection dust, chlorine bypass dust and desalted dust

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