JP2017095300A - Cement clinker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a cement clinker capable of reducing a burning temperature during manufacturing, capable of increasing waste using amount compared to conventional cement clinkers and providing a cement physical properties equal to conventional ones even with higher f-CaO compared to conventional ones.SOLUTION: By setting a clinker with total amount of CA and CAF calculated by a Bogue equation of 22% to 32%, CS amount of 60% to 63% and iron modulus (I.M.) of 0.8 to 1.3, equal coagulation property and strength development are obtained even when f-CaO is 1.0% to 2.0% which is higher than conventional ones.SELECTED DRAWING: None

Description

  The present invention relates to a cement clinker and a cement composition. More specifically, the present invention relates to a cement clinker and a cement composition having a composition that exhibits good physical properties even when fired at a lower temperature than conventional ones.

The cement industry is a mass production and mass consumption type industry, and resource and energy saving are the most important issues. For example, the most manufactured pordoland cement needs to be clinkered by firing a raw material adjusted to a predetermined chemical composition at a high temperature of 1450 ° C. to 1550 ° C. It is. That is, energy can be reduced if the firing temperature of the clinker can be reduced. A technique for increasing C ₄ AF (4CaO.Al ₂ O ₃ .Fe ₂ O ₃ ), which is a main clinker mineral, has been developed to reduce the clinker firing temperature. (Patent Document 1)

On the other hand, in relation to recent global environmental problems, effective use of wastes and by-products has become an important issue. Taking advantage of the characteristics of the cement industry and cement production equipment, it is effective from the viewpoint of safe and mass disposal to effectively use or treat waste as raw material and fuel during cement production. Many wastes and by-products have a high Al ₂ O ₃ content, and in the above-described system in which C ₄ AF is increased, the Al ₂ O ₃ content of the cement clinker is higher than that of the conventional Portland cement clinker. More waste and by-products can be used than conventional Portland cement clinker. Also in this point, the clinker described in Patent Document 1 is excellent.

Japanese Patent No. 5656638

  Even if it can be fired at a lower temperature than in the past, it does not make sense if the physical properties of the cement produced from the clinker obtained are significantly lower than those of conventional cement. There is f-CaO as a firing index in the clinker firing. Conventional cement clinker is generally manufactured so that f-CaO is 1.0% or less, and it is general that no problem is caused in cement physical properties when the content is 1.0% or less. However, in order to surely reduce f-CaO to 1.0% or less, it is necessary to produce with sufficient thermal energy in the firing step, and in some cases, excessive thermal energy may be applied. Since the clinker described in Patent Document 1 can be fired at a lower temperature than before, it can be manufactured with energy saving than before. However, since the f-CaO is attempted to be 1.0% or less than the conventional, excessive heat is required. When energy is applied, the original energy saving effect cannot be obtained sufficiently.

  Therefore, the present invention can reduce the firing temperature during production compared to conventional cement clinker, can increase the amount of waste used, and even if f-CaO is higher than conventional, An object of the present invention is to provide a cement clinker and a cement composition capable of obtaining cement properties equivalent to those of the above.

In order to solve the above-mentioned problems, the present inventors proceeded with intensive studies, and by setting the total amount of C ₃ A and C ₄ AF, the amount of C ₃ S, and IM within a predetermined range, f-CaO is 1.0%. The present inventors have found that sufficient cement physical properties can be obtained even when exceeding the above, and have completed the present invention.

That is, according to the present invention, the total amount of C ₃ A and C ₄ AF calculated by the Borg formula is 22% to 32%, the amount of C ₃ S is 60% to 63%, and the iron ratio (IM) is It is a cement clinker having 0.8 to 1.3 and f-CaO of 1.0% to 2.0%.

  According to the present invention, it is possible to obtain a cement clinker that can be fired at a lower temperature than before and that can increase the amount of waste and by-products used without opening excessive heat energy.

The amounts of C ₃ A, C ₄ AF and C ₃ S in 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 analysis 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 rate (HM), the silicic rate (SM), the activity coefficient (AI), and the lime saturation (LSD). It is obtained by using the main chemical component values, and is used as one of the frequency and ratio as a characteristic value for clinker production management. In the following, the calculation method of the iron ratio is described 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 )
Iron ratio (IM) = Al ₂ O ₃ / Fe ₂ O ₃
Activity coefficient (AI) = SiO ₂ / Al ₂ O ₃
Lime saturation (LSD) = CaO / (2.8 × SiO ₂ + 1.2 × Al ₂ O ₃ + 0.65 × Fe ₂ O ₃ )

“CaO”, “SiO ₂ ”, “Al ₂ O ₃ ” and “Fe ₂ O ₃ ” in the above are JIS R 5202 “Chemical analysis method of Portland cement” and JIS R 5204 “Fluorescence X of cement”, respectively. It can be measured by a method conforming to “line analysis method” or the like.

In the cement clinker of the present invention, 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 at a temperature of 1300 to 1400 ° C. A more preferable total amount is 24% or more. As will be described later, C ₃ S needs to be 60% 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 40%. Preferably it is 35% or less, More preferably, it is 32% or less, Most preferably, it is 28% or less. Of these components, C ₄ AF is preferably present alone at 15% or more in that it can be sufficiently sintered at low temperatures and the amount of f-CaO in the clinker can be reduced.

The cement clinker of the present invention has a C ₃ S content of 60 to 63%. If it is less than 60%, it is difficult to obtain sufficient strength. On the other hand, 63% or less is preferable from the viewpoint of easy firing.

The cement clinker of the present invention may further contain C ₂ S. The amount is 17% or less, and preferably 3% or more. From the viewpoint of obtaining long-term strength, it is particularly preferably an amount such that the total amount with the C ₃ S amount is 69% or more.

  The most important thing in the cement clinker of the present invention is to set the iron ratio (IM) to 0.8 to 1.3 or less. When the iron ratio is less than 0.8, sufficient coagulation properties cannot be obtained, it becomes difficult to form a cured product, and strength development cannot be obtained. When the iron ratio exceeds 1.3, sufficient strength development (more specifically, for example, mortar strength development) cannot be obtained even if the other requirements in the cement clinker of the present invention are satisfied. Further, when the iron ratio exceeds 1.3, the time from the start to the end of the setting tends to be too long. From this point, the iron ratio is set to 0.8 to 1.3. A more preferable range of the iron ratio is 1.0 to 1.3.

  The hydraulic modulus and silicic acid rate are not particularly limited, but the hydraulic modulus is preferably 1.8 to 2.2, particularly preferably 1.9, in order to achieve an excellent balance of various physical properties. The silicic acid ratio is preferably 1.0 to 2.0, and particularly preferably 1.1 to 1.7.

  The f-CaO of the cement clinker of the present invention is 1.0 to 2.0%. That is, since f-CaO is 1.0% or more, it is not necessary to perform excessive firing at the time of firing with a cement kiln, which is advantageous in terms of energy. On the other hand, if it exceeds 2.0%, the strength development is markedly reduced and abnormal condensation occurs, so the content is made 2.0% or less.

  The method for producing the cement clinker of the present invention is not particularly limited, and a known cement raw material is prepared and mixed at a predetermined ratio so as to have the above-mentioned mineral ratios and coefficients, and a known method (for example, SP kiln). Or an NSP kiln or the like). The amount of f-CaO usually decreases as the firing temperature is higher or the firing time is longer.

As a method for preparing and mixing the cement raw material, a known method may be adopted as appropriate. 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 scrap, waste white clay, waste, tires, shells, municipal waste and incinerated ash. is there).

In particular, the cement clinker of the present invention contains many minerals such as C ₃ A and C ₄ AF whose constituent elements are Al ₂ O ₃ . Therefore, with the advantage that as compared with the conventional cement clinker, Al ₂ O ₃ content of more waste and by-products can be prepared using more of.

  The cement clinker produced by the production method of the present invention can be made into a cement by pulverizing or separately pulverizing with gypsum and mixing after mixing with the gypsum. Examples of the cement include ordinary Portland cement, early-strength Portland cement, and ultra-early-strength Portland cement. 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.

When gypsum is added to make cement, gypsum to be used can be used without particular limitation as a gypsum known as a raw material for producing cement such as dihydrate gypsum, semi-water gypsum, and anhydrous gypsum. In the case of Portland cement, the amount of gypsum added is preferably so that the amount of SO ₃ is 1.5 to 5.0% by mass, such that the amount is 1.8 to ₃ % by mass. Is more preferable. As for the above-mentioned cement clinker and gypsum grinding method, known techniques can be used without any particular limitation.

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

The fineness of the cement is not particularly limited, but is preferably adjusted to 2800 to 4500 cm ² / g in terms of the specific surface area of branes.

  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.

The raw materials were adjusted using industrial raw materials including waste, and fired at 1450 ° C. and 1350 ° C. in an electric furnace to obtain a cement clinker. Gypsum was added to this cement clinker so that it would be 2 ± 0.2% in terms of SO ₃ , and mixed and ground so that the specific surface area by the Blaine method would be 3200 ± 50 cm ² / g to produce each cement. Table 1 shows the firing temperature at the time of firing in each Example / Comparative Example, and the mineral composition and various ratios / coefficients of the clinker obtained after firing according to the Borg formula. Table 2 shows the measurement results of the mortar compressive strength and the time required from the start to the end of setting after the cement clinkers obtained in these Examples and Comparative Examples were made into cement by the above-described method.
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 f-CaO: Cement Association Standard Test Method I-01 Measured according to a method for quantifying free calcium oxide.
(3) Measurement of mortar compressive strength: It was measured by a method based on JIS R 5201.
(4) Setting time: measured by a method according to JIS R 5201.

  The reference example is an example showing the result of firing a cement clinker having a conventional standard composition at a standard temperature. That is, the quality of each example / comparative example is discussed as the result and reference of this reference example.

  Examples 1 to 3 relate to the present invention, and the raw materials are fired at 1350 ° C. and 100 ° C. lower than the clinker of the composition of the reference example, and the f-CaO is 1.0 to 2.0%. It has become. In any case, the mortar compressive strength up to the age of 3 days is equal to or higher than that of the reference example, and the time from the start to the end of the setting is substantially equal to that of the reference example.

  Comparative Example 1 is an example in which the raw material is fired at 1350 ° C. and f-CaO is 1.0% or less. The mortar compressive strength up to the age of 3 days is equivalent to the reference example, but the time from the first start to the end is longer.

  In Comparative Example 2, the raw material is fired at 1350 ° C., and f-CaO is 2.0% or more. The mortar compressive strength until the age of 3 days is significantly reduced, and the initial setting time is also accelerated.

Claims (5)

The total amount of C ₃ A and C ₄ AF calculated by the Borg formula is 22% to 32%, the amount of C ₃ S is 60% to 63%, and the iron ratio (IM) is 0.8 to 1. 3 and a cement clinker having f-CaO of 1.0% to 2.0%. The cement clinker according to claim 1, wherein the amount of C ₄ AF is 15% or more. The cement clinker according to claim 1 or 2, wherein the total amount of C ₃ S and C ₂ S is 69% or more.   A cement composition comprising gypsum added to the cement clinker according to claim 1, 2 or 3.   The cement composition according to claim 4, further comprising at least one mixed material selected from the group consisting of blast furnace slag, siliceous mixed material, fly ash and limestone.