JP2000281399A - Cement clinker and cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a cement clinker which is obtained by using, as a raw material, coal ash in a large amount and which is useful for producing a cement composition having stable quality and excellent in compatibility with a water reducer such as lignin or naphthalene sulfonic acid, or the like, and to provide a cement composition using the same. SOLUTION: The cement clinker is obtained by using coal ash as a raw material and has a hydraulic modulus(H.M.) of 1.8 to 2.0, a silica modulus(S.M.) of 1.8 to 2.0 and an iron modulus (I.M.) of 1.8 to 2.8 and contains water-soluble alkali in an amount of 0.2 to 0.5%. The cement composition is obtained by mixing gypsum and the cement clinker so that the total amount of SO3 becomes 2.0 to 10.0% and pulverizing, or independently pulverizing each raw material and mixing. Further, the cement composition is mixed with at least one inorganic powder selected from blast furnace slag powder, fly ash and limestone powder, and, if necessary, with gypsum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement clinker using coal ash as a raw material and a cement composition using the cement clinker. A cement clinker that is stable and facilitates quality design, and is capable of producing a cement composition having good compatibility with a water reducing agent such as lignin-based and naphthalenesulfonic acid-based,
The present invention relates to a cement composition using the cement clinker.

[0002]

2. Description of the Related Art In recent years, in order to solve problems such as the development of unused resources and the use of industrial waste, coal ash discharged during the combustion of coal in thermal power plants, combustion furnaces of various factories, etc. It is desired to make effective use of. The amount of coal ash used for cement clinker is about 50 to 70 kg per ton of clinker. If you try to increase this amount,
The chemical composition of the cement clinker changes due to the influence of the chemical composition of the coal ash.

[0003] For example, as a method of effectively utilizing coal ash, a method of utilizing coal ash for producing special cement is disclosed in Japanese Patent Publication No. 1-49657. The Tokuhei 1-49657
The publication discloses the use of coal ash as a raw material for cement clinker.Specifically, by firing a crushed mixture of 100 parts by weight of coal ash and 200 to 400 parts by weight of limestone refined during coal combustion. A clinker containing 15-25% 3CaO.Al ₂ O ₃ is formed and then added to the clinker
Gypsum is mixed and pulverized so that the SO ₃ content is ₃ to 21%, or separated and pulverized and then mixed to form a large amount of ettringite of needle-like crystals of calcium sulfoaluminate hydrate when used. This is a method for producing special cement to obtain cement. And, as a target mineral when forming clinker, it is better to define the amount of 3CaO · SiO ₂ (C ₃ S), and it is desirable that the amount be about 50 to 60%.

[0004]

[Problems to be solved by the invention] Japanese Patent Publication No. 1-49657
According to the official gazette, to manufacture 1 ton cement clinker, coal ash
Is the one that uses 300-400kg (No. 1-449657)
Gazette Table 1). However, coal ash is
The chemical composition varies depending on the type of coal used and the combustion temperature.
It is known to differ greatly. For example, currently
In the overseas coal used, the chemical composition of coal ash is SiO_TwoBut
44.6-74.0%, Al_TwoO_Three16.4-38.3%, CaO 0.1-14.3
%, Fe_TwoO_ThreeIs reported to be in the range of 0.6-22.7%
Yes (coal ash issued by Japan Fly Ash Association 1998
Year). A cement clinker is manufactured using such coal ash.
In the case of manufacturing, simply C_ThreeS
Even if the amount is specified, other minerals (2CaO_Two, 3CaO ・ Al
_TwoO _Three, 4CaO ・ Al_TwoO_Three・ Fe_TwoO_Three) The amount of generated coal ash
It is different depending on the composition and has a certain quality
It is not possible to obtain tonklinker and cement compositions
there were.

When the chemical composition of the cement clinker changes, it becomes necessary to change the operating conditions during firing (for example, the amount of fuel used in the NSP kiln, the amount of production, the outlet temperature of the preheater, etc.). Was hard to say.

Generally, when producing a hydraulic compound (paste, mortar or concrete) using cement as a hydraulic binder, a water reducing agent is used to reduce the unit water volume or increase the softness. It is blended.
Conventionally, lignin-based and naphthalenesulfonic acid-based water reducing agents have been widely used as the water reducing agent. However, in a hydraulic compound using a special cement manufactured by the method described in Japanese Patent Publication No. 1-49657, the amount of a water reducing agent such as a lignin-based or naphthalenesulfonic acid-based is increased, resulting in a high cost. There was also the problem of becoming.

[0007]

Means for Solving the Problems In view of the above problems, the present inventors have conducted intensive studies on a cement clinker using coal ash as a raw material and a cement composition using the cement clinker. hydraulic modulus of the cement clinker, a silicate ratio and iron ratio to a specific range, it is water-soluble alkali in the specified amounts, and gypsum to the cement clinker as total sO ₃ content is within a specific range mixing The present invention has been found to solve the above-mentioned problems by mixing and then pulverizing and / or separating and pulverizing and then mixing one or more inorganic powders selected from blast furnace slag powder, fly ash and limestone powder. Is completed.

[0008] That is, the present invention uses coal ash as a raw material, has a hydraulic hardness (HM) of 1.8 to 2.0, and a silicic acid ratio (SM) of 1.
A cement clinker (claim 1), characterized in that the cement clinker has an iron content (IM) of 1.8 to 2.8 and a water-soluble alkali of 0.2 to 0.5%. Preferably, 100 kg or more of coal ash is used as a raw material per ton of clinker (claim 2), and silicate waste containing alkali is preferably used as a raw material (claim 3). The present invention also provides the cement clinker with a total SO.
₃ weight of cement composition characterized by mixing after gypsum was mixed with either / or separated from each other pulverized pulverized so that 2.0 to 10.0% (claim 4). And furthermore,
A cement composition characterized by mixing the cement composition, one or more inorganic powders selected from blast furnace slag powder, fly ash, and limestone powder, and, if necessary, gypsum (claim 5).

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The cement clinker of the present invention uses coal ash as a raw material, and has a hydraulic modulus (HM), a silicate ratio (SM), and an iron ratio (I.
M.) is within a certain range, and contains a certain amount of a water-soluble alkali. Generally, in the production of cement clinker, the hydraulic hardness (HM) and the silicic acid ratio (S.
M.) and iron rate (IM). Therefore, in order to control the quality of the cement clinker and stabilize the operating conditions, it is indispensable to keep the above coefficients (HM, SM, IM) within a certain range. Clinker coefficients (H.
(M., SM, IM) within a certain range can stabilize the quality of cement clinker and stabilize the operating conditions even when coal ash with a significantly different chemical composition is used as a raw material. Becomes Since the quality of the cement clinker is stable, a cement composition using the cement clinker can also have a stable quality.

[0010] Coal ash is used as an alternative material to clay, but coal ash has a lower alkali content than clay. Therefore, in the cement clinker using the coal ash as a raw material, the content of the water-soluble alkali is reduced. Therefore, by including a certain amount of water-soluble alkali,
Compatibility with water reducing agents such as lignin and naphthalene sulfonic acid (including high performance water reducing agents and high performance AE water reducing agents) is improved. The phrase "compatible with the water reducing agent" in the present invention means that the same amount of the water reducing agent can improve the fluidity and reduce the amount of the same fluidity that can be obtained.

[0011] Each coefficient of the cement clinker is determined by the existence of coal ash.
Promotion of effective use of cement clinker and cement composition
Productivity (firing temperature, ease of firing, crushability, etc.), cement
Quality of the composition (amount of water reducing agent added, calorific value, coagulation, strength
Considering the actuality, etc.), the hydraulic coefficient (H.M.) is 1.8 to 2.0,
The acid ratio (S.M.) is 1.8-2.3 and the iron ratio (I.M.) is 1.8-2.8.
Preferably. In addition, each coefficient of cement clinker is
The raw material for cement clinker described below is in the above range.
Can be adjusted by mixing. Hydraulic modulus (H.
M.) becomes smaller, the pore phase (3C
aO ・ Al_TwoO_Three, 4CaO ・ Al_TwoO_Three・ Fe_TwoO_Three) High content
In the cement composition using the cement clinker,
The amount of water reducing agent used tends to increase. In addition, the gap phase
If the production is too large, the liquid phase in the kiln will increase,
Stable baking of the clinker becomes difficult. On the other hand, hydraulic
(H.M.) tends to increase the initial calorific value
It is in. Therefore, the hydraulic setting (H.M.) is preferably 1.8 to 2.0.
No. When the silicic acid ratio (S.M.) decreases, cement clean
Interstitial phase in mosquito (3CaO ・ Al_TwoO _Three, 4CaO ・ Al_TwoO_Three・ Fe_TwoO_Three)of
Content is increased, cement cement using the cement clinker
In the composition, the amount of the water reducing agent used tends to increase.
Also, if the amount of generated interstitial phase becomes too large,
The liquid phase increases, making it difficult to sinter the clinker stably.
On the other hand, when the silicic acid ratio (S.M.) increases, coal ash is cleared.
It becomes difficult to use in large quantities as a raw material for coal,
Achieved the purpose of the present invention to promote the effective use of coal ash
It is difficult to achieve. Therefore, the silicic acid rate (S.M.)
Is preferably 1.8 to 2.3. When the iron ratio (I.M.) increases,
3CaO ・ Al in cement clinker_TwoO_ThreeHigh content of
In the cement composition using the cement clinker,
Use of water reducing agent increases. Also, the initial calorific value increases
I do. On the other hand, when the iron ratio (I.M.)
The crushability of the linker is reduced, and the productivity of the cement composition is poor.
It becomes. Therefore, the iron ratio (I.M.) is preferably 1.8 to 2.8.
No.

The amount of the water-soluble alkali is preferably from 0.2 to 0.5%, more preferably from 0.25 to 0.40%. When the amount of the water-soluble alkali is other than 0.2 to 0.5%, the amount of the lignin-based or naphthalenesulfonic acid-based water reducing agent increases.

As coal ash as a raw material for cement clinker
Means when coal is burned in thermal power plants, various factories, etc.
Coal ash generated in, for example, fly ash, cinder
Ash, bottom ash, clinker ash, etc.
Can be used. In the present invention,
In order to adjust the chemical composition of coal to the above range,
Outside, CaO raw material, SiO_TwoRaw materials and Fe_TwoO_ThreeNeed to use raw materials
There is. Here, limestone, quicklime,
Slaked lime or the like can be used. In addition, SiO_TwoAs raw material
For example, silica stone, clay or the like can be used. further,
Fe_TwoO _ThreeUse iron slag, iron cake, etc. as raw materials
Can be.

Since each of the above-mentioned raw materials has a low alkali content, the amount of the water-soluble alkali in the clinker can be reduced only by the above-mentioned raw materials.
It is difficult to adjust to 0.2-0.5%. Therefore, in the present invention, it is necessary to further add an alkali source.
Most of the water-soluble alkali in conventional Portland cement is sodium sulfate, potassium sulfate or a solid solution thereof.
It is preferable to add ₂ O feed and / or K ₂ O feed. Examples of the alkali source include Na ₂ CO ₃ and K ₂ CO ₃ ,
It is preferable to use silicate-based waste containing alkali such as waste glass and pearlite waste, because this also leads to further effective use of industrial waste. In the present invention, the content of the water-soluble alkali is `` ASTM C-114 S17.
2 ".

The cement clinker of the present invention is obtained by mixing the above-mentioned raw materials so as to have predetermined HM, SM, IM and water-soluble alkali amounts, and firing the mixture. If the amount of alkali in the raw material is approximately 0.6 to 1.0%, a predetermined amount of water-soluble alkali can be obtained. In the present invention, the method of mixing the respective raw materials is not particularly limited, and may be performed using a conventional apparatus or the like. Also, the firing of the cement clinker may be performed by a conventional apparatus (NSP kiln, SP kiln, etc. used for firing Portland cement clinker).

In the present invention, from the viewpoint of promoting the effective use of coal ash, it is preferable to use 100 kg or more of coal ash as a raw material per 1 ton of the cement clinker, and more preferably 150 to 350 kg. If the amount of coal ash used exceeds 350 kg, it becomes difficult to adjust the hydraulic modulus (HM), the silicate ratio (SM) and the iron ratio (IM) of the cement clinker to predetermined ranges.

Next, the cement composition of the present invention will be described. The cement composition of the present invention is obtained by mixing gypsum with the above-mentioned cement clinker so that the total SO ₃ content is 2.0 to 10.0%, and then pulverizing the mixture, or after mutually separating and pulverizing, mixing. From the viewpoint of the productivity of the cement composition, it is preferable to mix gypsum with the cement clinker and grind it. Total SO
_{If the} amount is less than 2.0%, abnormal setting such as rapid setting may occur, which is not preferable. On the other hand, if the total SO ₃ amount exceeds 10.0%, the setting is undesirably delayed. 2 for plaster
Water, hemihydrate, anhydrous gypsum and mixtures thereof. The apparatus used for pulverization is not particularly limited, and a ball mill or the like conventionally used for pulverizing Portland cement clinker can be used. The cement composition preferably has a Blaine specific surface area of 3000 to 4500 cm ² / g.

The cement composition of the present invention is a mixture of the cement composition, one or more inorganic powders selected from blast furnace slag powder, fly ash, and limestone powder, and, if necessary, gypsum. . In this case, the fineness and mixing ratio of the inorganic powder to be mixed differ depending on the performance of the intended cement and the type of the inorganic powder. For example, if the blast furnace slag powder, the specific surface area of the brane 2500 ~
10000 cm ² / g, preferably those of 3500~8000cm ² / g, 80
It is preferable to mix them in percentages of not more than%. Also, if limestone powder, the Blaine specific surface area 2500~20000cm ² / g, preferably those 3000~10000cm ² / g, preferably be mixed in an inner split 50% or less. Also, in the cement composition containing the inorganic powder, since the total SO ₃ amount is preferably 2.0 to 10.0%, when the total SO ₃ amount is less than 2.0% by mixing with the inorganic powder, Gypsum also needs to be added. Gypsum includes dihydrate, hemihydrate, anhydrous gypsum and mixtures thereof, with a Blaine specific surface area of 3000-45.
It is preferred to use one of 00 cm ² / g. The method of mixing the inorganic powder (and gypsum as necessary) is not particularly limited.

The cement composition of the present invention is used in the form of paste, mortar or concrete. As the water reducing agent, it is preferable to use a lignin-based or naphthalenesulfonic acid-based water reducing agent (including a high-performance water reducing agent and a high-performance AE water reducing agent). When used in the form of mortar or concrete, mortar, fine and coarse aggregate used in the production of concrete, namely river sand, mountain sand, sea sand,
Crushed sand, river gravel, mountain gravel, sea gravel, crushed stone, etc. can be used. If necessary, an air entraining agent, an antifoaming agent, and the like can be added within a range that does not cause any trouble.

[0020]

The present invention will be described below with reference to examples. 1. Raw materials for cement clinker As raw materials for cement clinker, coal ash (two types), limestone, silica stone, iron cake, and waste glass having the chemical components shown in Table 1 were used.

[0021]

[Table 1]

The above raw materials were subjected to hydraulic set (HM) shown in Table 2;
The silica content (SM), iron content (IM), and water-soluble alkali content were blended and mixed by a conventional method, and the mixture was fired at 1400 ° C. using an NSP kiln to prepare a cement clinker. Table 2 also shows the water-soluble alkali content in each cement clinker measured according to “ASTM C-114 S17.2”.

[0023]

[Table 2]

Gypsum was added to each cement clinker so that the total SO ₃ amount was 3.7%, and mixed and pulverized to produce a cement composition having a Blaine specific surface area of about 3300 cm ² / g. In addition, the cement composition may be treated with a cement (Daiichi Cement Co., Ltd.,
Was added 50% inner dividing the blast furnace slag powder), further total SO ₃
A cement composition to which anhydrous gypsum was added so that the amount was 3.5% was also produced.

The following properties 1) and 2) were measured using each of the cement compositions. 1) Fluidity Water / cement = 0.33, fine aggregate / cement = 3.0, high performance water reducing agent / cement = 0.012, mortar is kneaded, and the mortar flow immediately after kneading is defined by JIS R 5201 (Physics of Portland Cement). Test method) ".
The kneading method conformed to "JIS R 5201 (physical test method for Portland cement)" (the high-performance water reducing agent was previously mixed with water). 2) Compression strength Water / cement = 0.5, fine aggregate / cement = 3.0 (without adding a high performance water reducing agent), 4 × 4 × according to “JIS R 5201 (Physical test method of Portland cement)” A 16 cm specimen was prepared, and the compressive strength was measured. The material age was 1, 7, and 28 days. Table 3 shows the results. The following were used as the high-performance water reducing agent, fine aggregate and water. High performance water reducing agent; "Mighty 150" (Kao Corporation, naphthalene sulfonic acid type) Fine aggregate; Ome ground sand Water; Tap water

[0026]

[Table 3]

Table 3 shows that even when coal ash having a significantly different chemical composition was used as a raw material, a cement composition of stable quality was obtained. In addition, a cement composition using a cement clinker containing 0.3% of a water-soluble alkali has a higher water-reduction performance than a cement composition using a cement clinker having a smaller water-soluble alkali content than the amount specified in the present invention. The flow was large even with the same amount of agent added.

[0028]

As described above, the cement clinker of the present invention has a hydraulic composition (HM), a silicic acid rate (SM) and an iron rate (IM) which are adjusted to a certain range. Stabilizes the quality of cement clinker without changing operating conditions during firing (for example, NSP kiln fuel consumption, production, preheater outlet temperature, etc.) It is possible and practical. Since the quality of the cement clinker is stable, a cement composition using the cement clinker can also have a stable quality.

Further, in the present invention, since 100 kg or more of coal ash is used as a raw material per 1 ton of the cement clinker, the effective use of coal ash can be promoted. Furthermore, the cement clinker of the present invention also contains a specific amount of a water-soluble alkali, and a cement composition using the cement clinker has excellent compatibility with a lignin-based or naphthalenesulfonic acid-based water reducing agent. It is.

Claims (5)

[Claims] (1) Coal ash is used as a raw material and has a hydraulic coefficient (H.
M.) is 1.8 to 2.0, silicic acid ratio (SM) is 1.8 to 2.3, iron ratio (IM) is 1.8 to 2.8, and water-soluble alkali is 0.2
A cement clinker characterized by containing 0.5% to 0.5%. 2. The cement clinker according to claim 1, wherein 100 kg or more of coal ash is used as a raw material per ton of clinker. 3. The cement clinker according to claim 1, wherein a silicate waste containing alkali is used as a raw material. 4. The cement clinker according to claim 1, wherein gypsum is mixed and pulverized so as to have a total SO ₃ content of 2.0 to 10.0% and / or separated and pulverized and then mixed. Cement composition. 5. A cement composition comprising the cement composition according to claim 4, and one or more inorganic powders selected from blast furnace slag powder, fly ash, and limestone powder, and, if necessary, gypsum. object.