JP5932478B2 - Cement composition and method for producing the same - Google Patents

Description

  The present invention relates to a cement composition and a method for producing the same. More specifically, the present invention relates to a cement composition that includes cement clinker and gypsum having different compositions calculated by the Borg formula and coefficients and various ratios, and exhibits good physical properties, and a method for producing the same.

  The cement industry is a mass-production / mass-consumption industry, and resource conservation and energy conservation are and will continue to be the most important issues. For example, in order to produce Portland cement, which is produced in the largest amount, it is necessary to sinter the raw material prepared in a predetermined chemical composition at a temperature as high as 1450 ° C. to 1550 ° C. to obtain a clinker. The energy cost to obtain is enormous.

  Further, the clinker obtained by firing at a higher temperature is mixed and pulverized together with gypsum and a mixed material to become cement, but the energy cost for obtaining electric power at the time of clinker pulverization also becomes large.

  Various methods have been tried and implemented to reduce energy costs, but in the category of general-purpose clinker, it is difficult to further reduce energy and power costs as well as further increase in waste usage. Yes. On the other hand, in connection with recent global environmental problems, effective use of waste, by-products, etc. has become an important issue. Taking advantage of the characteristics of the cement industry and cement production facilities, it is considered effective from the viewpoint of safe and mass disposal to effectively use or treat waste as raw material or fuel during cement production. However, with the advancement of cement utilization technology, the required performance for cement is becoming higher and higher.

Among wastes and by-products, municipal waste incineration ash, blast furnace granulated slag, blast furnace slow-cooled slag, etc., particularly coal ash, have a higher Al ₂ O ₃ content than ordinary cement clinker compositions, and Al ₂ When the usage amount of wastes, by-products and the like having a large O ₃ content is increased, the content of 3CaO · Al ₂ O ₃ (hereinafter, C ₃ A) in the cement clinker component is increased.

The C ₃ A is called a gap phase along with 4CaO.Al ₂ O ₃ .Fe ₂ O ₃ (hereinafter referred to as C ₄ AF), and there is an advantage that the calcination temperature of the clinker can be lowered when the amount thereof increases. on the other hand, other minerals constitutes an important clinker relative strength of the cement _{(3CaO · SiO 2 (C 3} S), 2CaO · SiO 2 (C 2 S)) affects the amount of influence on the cement properties Occurs.

In view of these points, compared to conventional cement clinker, it is possible to increase the amount of waste used, and it is possible to reduce the firing temperature during production, and it is as good as the conventional one As a cement clinker exhibiting a strong strength, the total amount of C ₃ A and C ₄ AF calculated by the Borg formula is 22% or more, the C3S amount is 60% or more, and the iron ratio (IM) A cement clinker (hereinafter also referred to as “low-IM clinker”) having a value of 1.3 or less has been proposed (Japanese Patent Application No. 2011-093396).

JP 2004-352515 A

  However, in further studies by the present inventors, it has been found that the cement composition using the low IM clinker is slightly inferior in fluidity as compared with the conventional cement composition using a general-purpose clinker.

  Therefore, according to the present invention, it is possible to increase the amount of waste used as compared with the conventional general-purpose cement composition, and it is possible to reduce the firing temperature during production (energy cost can be reduced). The present invention aims to provide a cement composition that exhibits good strength development as well as conventional ones and is excellent in fluidity.

  As a result of diligent studies to solve the above problems, the present inventors have found that by mixing a conventional general-purpose cement clinker with a low IM clinker, the fluidity is dramatically improved. As a result of the investigation, the present invention was completed.

That is, the present invention relates to A clinker [the amount of C ₄ AF calculated by the Borg formula is 5 to 12%, the total amount of C ₃ A and C ₄ AF is less than 22%, and the amount of C ₃ S is 55% or more. And a cement clinker powder having an iron ratio (IM) of 1.3 to 2.3 and a B clinker [the amount of C ₄ AF calculated by the Borg formula is 15% or more, and C ₃ A and C ₄ the total amount of AF 22% or more, _{C 3} S content of 55% or more, and Tetsuritsu (i.m.) is seen containing a cement clinker] powder and gypsum powder is 1.3 or less, a It is a cement composition whose clinker and B clinker are 80: 20-40: 60 by mass ratio .

  According to the present invention, it is possible to increase the amount of waste used as a whole as compared with the conventional versatile cement composition, and it is possible to reduce the energy as a whole as compared with the conventional versatile cement composition. . Further, excellent fluidity can be obtained as a cement physical property. As a secondary effect, superior grindability can be obtained as compared with the case of producing conventional general-purpose cement.

The amounts of C ₃ A, C ₄ AF, C ₂ S and C ₃ S in the clinker of the present invention are determined by the Bogue equation.

  The Borg formula is used in conjunction with coefficients and various ratios, and is a calculation formula for calculating the approximate main compound composition using the main chemical component values, and is a formula well known to those skilled in the art. Describes how to determine the amount of each mineral in the clinker using the Borg formula.

C ₃ S amount = (4.07 × CaO) − (7.60 × SiO ₂ ) − (6.72 × Al ₂ O ₃ ) − (1.43 × Fe ₂ O ₃ )
C ₂ S amount = (2.87 × SiO ₂ ) − (0.754 × C ₃ S)
C ₃ A amount = (2.65 × Al ₂ O ₃ ) − (1.69 × Fe ₂ O ₃ )
C ₄ AF amount = 3.04 × Fe ₂ O ₃
In addition, the iron ratio (IM) is the hydraulic ratio (HM), silicic acid ratio (SM), activity coefficient (AI), and lime saturation (LSD). ), And is used as one of the coefficients and ratios as characteristic values for clinker production control, and is well known to those skilled in the art. Therefore, the calculation method of the iron ratio is described below together with other coefficient values.

Hydraulic modulus (HM) = CaO / (SiO ₂ + Al ₂ O ₃ + Fe ₂ O ₃ )
Silicic acid ratio (SM) = SiO ₂ / (Al ₂ O ₃ + Fe ₂ O ₃ )
Activity coefficient (AI) = SiO ₂ / Al ₂ O ₃
Iron ratio (IM) = Al ₂ O ₃ / Fe ₂ O ₃
Lime saturation (LSD) = CaO / (2.8 × SiO ₂ + 1.18 × Al ₂ O ₃ + 0.65 × Fe ₂ O ₃ )
In the above formula, “CaO”, “SiO ₂ ”, “Al ₂ O ₃ ” and “Fe ₂ O ₃ ” are JIS R5202 “Chemical analysis method of Portland cement” and JIS R5204 “Fluorescence X-ray analysis method of cement”, respectively. ”And the like.

The A clinker of the present invention has a C ₄ AF amount of 5 to 12%, a total amount of C ₃ A and C ₄ AF of less than 22%, a C ₃ S amount of 55% or more, and an iron ratio (I .. M.) is a clinker of 1.3 to 2.3. The A clinker corresponds to a general-purpose ordinary Portland cement clinker or an early-strength Portland cement clinker. Such a clinker is excellent in various physical properties such as strength development and fluidity, but requires a high temperature of about 1450 ° C. for its production.

On the other hand, the B clinker has a C ₄ AF amount of 15% or more, a total amount of C ₃ A and C ₄ AF of 22% or more, a C ₃ S amount of 55% or more, and an iron ratio (IM .) Is a clinker of 1.3 or less.

In the B clinker, C ₄ AF exists alone at 15% or more in that it can be sufficiently sintered even at a low temperature of 1300 to 1400 ° C. and the amount of f-CaO in the B clinker can be reduced. It is necessary to let Further, a large amount of C ₄ AF in the B clinker has an advantage of improving its grindability.

The total amount of C ₃ A and C ₄ AF must be 22% or more. When these amounts are less than 22%, it becomes difficult to obtain a cement clinker having good physical properties such as strength development by firing at a low temperature. A more preferable total amount is 24% or more. As will be described later, C ₃ S is required to be 55% or more in order to obtain high strength development. Therefore, the upper limit of the total amount of C ₃ A and C ₄ AF is 45%. Preferably it is 35% or less, More preferably, it is 32% or less, Most preferably, it is 28% or less.

If the amount of C ₃ S in the B clinker is less than 55%, good strength development cannot be obtained in the cement composition of the present invention. The lower limit of the amount of C ₃ S is lower than the low IM clinker proposed in the above-mentioned Japanese Patent Application No. 2011-093396 because the B clinker is used in combination with the A clinker in the present invention.

In order to obtain good strength development of the cement composition using the A and B clinker of the present invention, the amount of C ₃ S in the A and B clinker is important. In order to obtain a strength development property equivalent to a general-purpose cement composition, the C ₃ S amount of each of the A clinker and the B clinker should be 55% by mass or more. The amount of C ₃ S in each of the A, B clinker is preferably 60% by mass or more, and more preferably 62% by mass or more.

  The cement composition of the present invention has the greatest feature in that both the A clinker and the B clinker are used. Compared to the case of using the clinker alone as the clinker, the combination of the B clinker has the same or higher fluidity, and the temperature required for the production of the B clinker is low, and it is easy to grind. There is an advantage that the total energy cost for manufacturing can be reduced. Here, the reason why the B clinker is not used alone is that the fluidity tends to be slightly lowered as compared with the case of the A clinker alone.

  In the cement composition of the present invention, the higher the ratio of B clinker, the lower the manufacturing cost for firing and pulverization. In consideration of this point, the ratio of A clinker to B clinker can be set within an arbitrary range. The mass ratio is preferably 99: 1 to 1:99, more preferably 80:20 to 10:80. It is preferably 80:20 to 40:60 from the standpoint that better fluidity can be obtained than when A clinker or B clinker is used alone.

  The method for producing the A and B clinkers used in the present invention is not particularly limited, and known clinker (cement) raw materials are prepared and mixed at a predetermined ratio so as to have the above-mentioned mineral ratios and coefficients. (E.g., SP kiln or NSP kiln).

A known method may be appropriately adopted as a method for preparing and mixing each clinker raw material. For example, waste, by-products and other raw materials in advance (CaO sources such as limestone, quicklime and slaked lime, SiO ₂ sources such as silica, Al ₂ O ₃ sources such as clay, Fe ₂ O ₃ sources such as iron sources, etc.) Is measured, the blending ratio of each raw material is calculated so as to be within the above range from the ratio of each component in these raw materials, and the raw material is blended at that ratio.

  In addition, the raw material used with the manufacturing method of this invention can use the same thing as the raw material conventionally used in manufacture of a cement clinker without a restriction | limiting in particular. Of course, it is possible to use waste and by-products.

  In the production method of the present invention, it is preferable to use one or more kinds of wastes from wastes, by-products and the like from the viewpoint of promoting effective utilization of wastes, by-products and the like. Specific examples of usable waste and by-products include blast furnace slag, steelmaking slag, non-ferrous iron slag, coal ash, sewage sludge, purified water sludge, papermaking sludge, construction generated soil, foundry sand, dust, incineration fly ash, melting Examples include fly ash, chlorine bypass dust, wood waste, waste white clay, waste, tires, shells, municipal waste and incinerated ash (including clinker raw materials (components) and thermal energy. Some are sources).

In particular, the B clinker in the present invention contains a large amount of C ₃ A and C ₄ AF minerals whose constituent elements are aluminum. Therefore, it has the advantage that it can be manufactured using more waste and by-products containing a large amount of aluminum, compared to a cement clinker that has been conventionally used for general purposes.

In the cement composition of the present invention, gypsum is blended in the same manner as conventionally known cement compositions. That is, it is used to adjust the setting time when the cement composition of the present invention is mixed with water. In the present invention, the amount of gypsum is not particularly limited, but generally 1.0 to 5.0% by mass, preferably 1.8 to 3.0% in terms of SO _{3 in the} cement composition. % By mass.

  As the type of gypsum to be used, gypsum known as gypsum for cement composition can be adopted, and specifically, by-product gypsum, such as flue gas desulfurization gypsum and phosphate gypsum, and natural gypsum gypsum. , Semi-water gypsum, type II anhydrous gypsum and the like.

In the cement composition of the present invention, the above A clinker, B clinker and gypsum are all contained in powder. As the fineness, Blaine specific surface area of the cement composition, preferably 2000~8000cm ² / g, more preferably from 2800~4500cm ² / g.

  The method for producing a cement composition having a fineness as in the above example is not particularly limited. For obtaining a final cement composition powder, for example, (1) A clinker, B clinker and gypsum (2) A method of pulverizing a mixture of A clinker and B clinker and mixing separately crushed gypsum, (3) A mixture of A clinker and gypsum Thereafter, a method of pulverizing, separately mixing B clinker and gypsum, and then mixing the pulverized material may be used. For the pulverization itself, a known pulverizer such as a ball mill or a vertical pulverizer can be used.

  The cement composition of the present invention can be used as ordinary Portland cement, early-strength Portland cement, ultra-early-strength Portland cement and the like. In addition to Portland cement, it can also be used as a constituent of various mixed cements and solidifying materials such as soil solidifying materials.

  In addition, the cement composition is appropriately mixed with a blast furnace slag, siliceous mixed material, fly ash, calcium carbonate, limestone, or a grinding aid and mixed or pulverized, or mixed with the mixed material after pulverization. Also good. Further, chlorine bypass dust or the like may be mixed.

  Further, if necessary, blast furnace slag, fly ash or the like can be mixed after pulverization to obtain blast furnace slag cement, fly ash cement or the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to these Examples.

  Using industrial raw materials containing waste, the raw materials were adjusted to obtain a general-purpose cement clinker composition corresponding to A clinker and a clinker having a composition corresponding to B clinker on a calcined basis, and 1450 ° C. and 1350 ° C., respectively. The cement clinker was obtained by baking at 90 ° C. for 90 minutes. Table 1 shows the mineral composition and coefficient values of the clinker obtained after firing the A clinker and the B clinker according to the Borg formula.

Gypsum is added to a cement clinker mixed with each of these cement clinker individually or in a predetermined ratio so as to be 2 ± 0.2% in terms of SO ₃ , and the specific surface area by the Blaine method becomes 3200 ± 100 cm ² / g. Each cement was crushed in the manner described above and each cement was trial manufactured.

Various measurement methods are as follows.
(1) Measurement of chemical composition of raw material and cement clinker: Measured by a fluorescent X-ray analysis method according to JIS R 5204.
(2) Measurement of mortar compressive strength: It was measured by a method based on JIS R 5201.
(3) Setting time: measured by a method based on JIS R 5201.
(4) Paste flow measurement: Measured according to JASS 15 M-103, mixing time with Hobart mixer is 3 minutes, water-solid ratio 0.5 (mass ratio), no admixture added, test temperature The paste flow was measured immediately after tempering at 20 ° C.
(5) Grindability: Portland clinker (hereinafter, also simply referred to as clinker) was coarsely pulverized to less than about 5 mm by a jaw crusher to obtain a coarse powder clinker. A predetermined 2 water gypsum (2% by mass in terms of SO _{3 with} respect to the clinker) was added to 2 kg of the coarse powder clinker to prepare a mixture.

Was added grinding aid to the mixture, Blaine specific surface area in a pot mill having an inner volume of 10L was obtained Shisei cement ground to ^{3200cm 2 / g (± 100cm 2} / g). The confirmation of pulverization was performed by measuring the time from the start of pulverization by the pot mill until the brane specific surface area of the cement reached 3100 cm ² / g. The grindability is shown as a relative ratio when the time required for grinding in Comparative Example 1 is 100.

Comparative Examples 1 and 2
Table 2 shows the measurement results of mortar compressive strength, coagulation, paste flow and grindability when A clinker and B clinker are used alone.

Examples 1 to 3, Comparative Example 3
Table 2 shows the measurement results of mortar compressive strength, coagulation, paste flow and grindability for the mixture of A clinker and B clinker in the proportions shown in Table 2.

Comparative Example 1 is an example showing the results of a physical property test of a cement composition made by trial production from a clinker obtained by firing a raw material having a general composition corresponding to clinker A at a standard firing temperature of 1450 ° C. Comparative Example 2, to the general composition corresponding to clinker B is increased to C ₄ AF amount is an example showing the results of physical property tests of the cement composition Shisei from clinker fired at 1350 ° C.. That is, the quality of the results of each example will be discussed as the results and criteria of Comparative Examples 1 and 2.

Examples 1 to 3 relate to the present invention, and are the results of physical property tests of the respective cement compositions produced from a mixed clinker obtained by mixing clinker corresponding to clinker A and clinker corresponding to clinker B in a predetermined ratio. It is an example which shows.

As the amount of clinker B mixed with clinker A increases, the amount of waste used as a whole cement composition increases and the effect of reducing the firing energy increases. Furthermore, the grindability is good and the energy reduction effect by grinding is increased. In addition to these, in Examples 1 to 3, particularly good fluidity is obtained. Comparative Example 3 tends to be somewhat inferior in fluidity.

Claims (5)

A clinker (the amount of C ₄ AF calculated by the Borg formula is 5 to 12%, the total amount of C ₃ A and C ₄ AF is less than 22%, the amount of C ₃ S is 55% or more, and the iron ratio Cement clinker (I.M.) is 1.3 to 2.3] powder and B clinker [the amount of C ₄ AF calculated by the Borg formula is 15% or more, and the total of C ₃ A and C ₄ AF the amount is more than 22%, _{C 3} S content is 55% or more, and Tetsuritsu (i.m.) is seen containing a cement clinker] powder and gypsum powder is 1.3 or less, a clinker and B clinker Is a cement composition having a mass ratio of 80:20 to 40:60 . After mixed-and crushed the A clinker and B clinker, or mixing gypsum powder, or A clinker process according to claim 1 cement composition according B to clinker and simultaneously mixing and grinding gypsum.   The method for producing a cement composition according to claim 1, comprising a step of mixing and pulverizing A clinker and gypsum, a step of mixing and pulverizing B clinker and gypsum, and a step of mixing both pulverized products.   The cement composition according to claim 1, further comprising at least one mixed material selected from the group consisting of blast furnace slag, siliceous mixed material, fly ash and limestone.   Furthermore, the manufacturing method of the cement composition of Claim 2 or 3 including the process of mixing any 1 or more types of mixed materials chosen from the group which consists of blast furnace slag, a siliceous mixed material, fly ash, and limestone.