JP2018158850A - Method for producing cement clinker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a clinker capable of consuming a large amount of wastes and by-products, calcinable at a low temperature of less than 1400°C, and having both high strength and low f-CaO content. SOLUTION: The C3S amount calculated by the Borg equation is 61% or more, the C4AF amount is 12 to 15%, the total amount of C3A and C4AF is 22% or more, and the iron rate (IM) is 1.40. A clinker having a low f-CaO value of less than 1.0% even when calcined at a low temperature of less than 1400° C. and a good strength development by adjusting the raw material ratio so as to be 1.80. [Selection diagram] None

Description

  The present invention relates to a cement clinker and a method for producing a cement composition. Specifically, the present invention relates to a production method capable of obtaining a clinker having an f-CaO content of less than 1.0% even when fired at a lower temperature than in the past.

  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.

Of major minerals clinker firing temperature reduction of clinker, techniques for increasing the a gap phase _{C 3 A (3CaO · Al 2} O 3) and _{C 4 AF (4CaO · Al 2} O 3 · Fe 2 O 3) Has been developed.

For example, in Patent Document 1, the total amount of C ₃ A and C ₄ AF is 22% or more and the iron ratio (IM) is 1.3 or less, so that the clinker firing temperature is 1300 to 1400 ° C. Making it possible.

Non-Patent Document 1 shows that the firing temperature can be lowered by increasing the amount of C ₃ A.

Further, 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 content of Al ₂ O _3, and a clinker with a large amount of C ₃ A or C ₄ AF is advantageous in that it can use a large amount of such waste (for example, Patent Document 2).

Japanese Patent No. 5656638 JP 2004-352515 A

Yasuko et al., "Development of energy-saving general-purpose cement", Abstracts of the 68th Cement Technology Conference, 2014, p210-211

  However, the clinker described in Patent Document 1 still has room for improvement in terms of strength. Furthermore, since the iron ratio needs to be 1.3 or less, the proportion of aluminum cannot be increased beyond a certain level, and there is room for improvement from the viewpoint of waste use.

When the clinker described in Non-Patent Document 1 is fired at a low temperature of 1400 ° C. or less, f-CaO tends to remain, and if it is attempted to reduce f-CaO to less than 1.0%, the temperature reduction effect is only about 5-15 ° C. There was a problem that it could not be obtained. Further, this clinker has a C ₃ S amount that contributes to strength development of 60%, and a higher C ₃ S amount is required to obtain high strength, but C ₃ S is a mineral that is difficult to be fired. Increasing the amount is expected to make it more difficult to burn (the amount of f-CaO increases or the temperature reduction effect decreases).

Accordingly, an object of the present invention is to provide a method for producing a clinker that can consume a large amount of waste and by-products, can be fired at a low temperature of less than 1400 ° C., and has both high strength and a low amount of f-CaO. To do.

In order to solve the above-mentioned problems, the inventors of the present invention have made extensive studies, and have a composition in which the amount of C ₃ S is increased in order to develop high strength. Even when fired at a low temperature of less than 1400 ° C., f-CaO is not formed. The present inventors have completed the present invention by finding a composition capable of obtaining a cement clinker of less than 1.0%.

That is, the present invention is a method for producing a Portland cement clinker having a C ₃ S amount calculated by the Borg formula of 61% or more and f-CaO of less than 1.0% at a firing temperature of less than 1400 ° C.,
The C ₃ S amount calculated by the Borg formula is 61% or more, the C ₄ AF amount is 12 to 15%, the total amount of C ₃ A and C ₄ AF is 22% or more, and the iron ratio after firing A raw material ratio is adjusted so that (I.M) is 1.40 to 1.80.

  According to this invention, it becomes possible to reduce a calcination temperature to about 1300-1400 degreeC significantly lower than the conventional clinker. Furthermore, a relatively large amount of waste and by-products can be used as raw materials, and good strength development can be obtained.

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 ratio (HM), the siliceous ratio (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 present invention, the raw material is prepared so that the amount of C ₃ S after firing is 61% or more. C ₃ S is a mineral that contributes to the development of long-term strength at an early stage, and as it increases, there is a tendency that higher strength is obtained, but on the other hand, it is difficult to burn (requires a higher firing temperature). Therefore, if this amount is less than 60%, it is easy to make f-CaO less than 1.0% at the time of firing at a low temperature, but the amount of C ₃ A and C ₄ AF and the iron ratio described later are set to a predetermined value. Even if it is within the range, good strength development cannot be obtained.

The amount of C ₃ S is preferably 62% or more, and particularly preferably 63% or more. Since the total amount of C ₃ A and C ₄ AF described later is at least 22%, the upper limit of the C ₃ S amount is 78%. In order to secure a certain time from the start to the end of the setting, it is preferably 70% or less, more preferably 65% or less.

In the present invention, the raw material is prepared so that the amount of C ₄ AF after firing is 12 to 15%. When the amount of C ₄ AF is large, the amount of f-CaO is decreased when the firing temperature is lowered.

In the present invention, the total amount of C ₃ A and C ₄ AF after firing 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 23% or more. On the other hand, if the total amount exceeds 32%, the amount of liquid phase is too large, which affects the kiln operation such as the development of coaching in the rotary kiln. A more preferable total amount is 28% or less.

The cement clinker produced in the present invention may further contain C ₂ S. The amount is 17% or less (C ₃ A is 61% or more and C ₃ A + C ₄ AF is 22% or more, and the total is 83% or more), 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 produced by the present invention is to set the iron ratio (IM) to 1.4 to 1.8. If the iron ratio is less than 1.4, sufficient coagulation properties cannot be obtained, and it becomes difficult to form a cured product, resulting in a decrease in strength development. When the iron ratio exceeds 1.8, firing at a low temperature becomes insufficient, f-CaO becomes high, and fluidity is lowered and condensation is abnormal.

  In the present invention, since the iron ratio is 1.4 to higher than the clinker described in Patent Document 1, waste and by-products containing aluminum can be used in a relatively large amount as a raw material.

  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 produced in the present invention is less than 1.0%. If it exceeds 1.0%, the initial heat of hydration increases, resulting in decreased fluidity and abnormal condensation. In order to make f-CaO less than 1.0%, raw materials may be prepared and fired so as to satisfy the total amount of C ₃ A and C ₄ AF and the iron ratio.

  In the present invention, the clinker is fired at a temperature of less than 1400 ° C. Moreover, in order to make baking sufficient, Preferably it is 1300 degreeC or more, More preferably, you may be 1350 degreeC or more.

  Firing is preferably performed in a rotary kiln (for example, an SP kiln or an NSP kiln) in consideration of industrial production.

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.
(1) Using industrial raw materials containing waste, the raw materials were adjusted to have each mineral composition on a firing base, and fired 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.
(2) Measurement of chemical composition of raw material and cement clinker: Measured by fluorescent X-ray analysis in accordance with JIS R 5204.
(3) Measurement of f-CaO: Cement Association Standard Test Method I-01 Measured according to the method for quantifying free calcium oxide.
(4) Measurement of mortar compressive strength: It was measured by a method based on JIS R 5201.

Example 1
The raw materials are calculated so that C ₃ S after firing is 64.4%, C ₂ S is 6.2%, C ₃ A is 13.3%, and C ₄ AF is 13.2% by calculation according to the Borg formula. Prepared. At this time, the iron ratio is 1.80, the hydraulic ratio is 2.11, and the silicic acid ratio is 1.57.

  This raw material was baked in an electric furnace at 1395 ° C. for 90 minutes. The amount of f-CaO of the obtained clinker was 0.55%. Table 1 shows the results of producing cement and measuring the mortar compressive strength.

Example 2
The raw materials are calculated so that C ₃ S after firing is 61.8%, C ₂ S is 12.6%, C ₃ A is 9.6%, and C ₄ AF is 13.4% according to the calculation by the Borg formula. Prepared. At this time, the iron ratio is 1.46, the hydraulic ratio is 2.09, and the silicic acid ratio is 1.90.

  This raw material was baked in an electric furnace at 1395 ° C. for 90 minutes. The amount of f-CaO of the obtained clinker was 0.50%. Table 1 shows the results of producing cement and measuring the mortar compressive strength.

Comparative Example 1
The raw materials are calculated so that C ₃ S after firing is 62.6%, C ₂ S is 11.6%, C ₃ A is 13.5%, and C ₄ AF is 9.5% according to the calculation by the Borg formula. Prepared. At this time, the iron ratio is 2.26, the hydraulic ratio is 2.16, and the silicic acid ratio is 2.00.

  This raw material was baked in an electric furnace at 1350 ° C. for 90 minutes. The amount of f-CaO of the obtained clinker was 3.24%. Table 1 shows the results of producing cement and measuring the mortar compressive strength.

Comparative Example 2
The raw materials are calculated so that C ₃ S after firing is 62.8%, C ₂ S is 7.2%, C ₃ A is 17.3%, and C ₄ AF is 9.7% according to the calculation by the Borg formula. Prepared. At this time, the iron ratio is 2.86, the hydraulic ratio is 2.15, and the silicic acid ratio is 1.61.

  This raw material was baked at 1350 ° C. for 90 minutes in an electric furnace. The amount of f-CaO of the obtained clinker was 3.53%. Table 1 shows the results of producing cement and measuring the mortar compressive strength.

Comparative Example 3
The raw materials were calculated so that C ₃ S after firing was 63.6%, C ₂ S was 6.7%, C ₃ A was 9.4%, and C ₄ AF was 17.4%. Prepared. At this time, the iron ratio is 1.26, the hydraulic ratio is 2.04, and the silicic acid ratio is 1.47.

  This raw material was baked at 1350 ° C. for 90 minutes in an electric furnace. The amount of f-CaO of the obtained clinker was 0.63%. Table 1 shows the results of producing cement and measuring the mortar compressive strength.

  Examples 1 and 2 relate to the present invention, and even when calcination is performed at a temperature lower than 1400 ° C., the f-CaO is sufficiently calcinated at 1.0% or less. Moreover, the mortar compressive strength of each age is favorable in any case.

Comparative Examples 1 and 2 correspond to those obtained by increasing the amount of C ₃ S in order to further improve the strength from the clinker composition described in Non-Patent Document 1. In any case, f-CaO has a high value exceeding 3.0%, and the mortar compressive strength is low as compared with the examples at each age.

  Comparative Example 3 corresponds to the clinker composition described in Patent Document 1. Although f-CaO is sufficiently fired to be less than 1.0%, the mortar compressive strength is lower than that of Examples in each material age.

Claims (3)

A method for producing a Portland cement clinker having a C ₃ S amount calculated by the Borg formula of 61% or more and f-CaO of less than 1.0% at a firing temperature of less than 1400 ° C.,
The composition after firing is such that the C ₃ S amount calculated by the Borg formula is 61% or more, the C ₄ AF amount is 12 to 15%, the total amount of C ₃ A and C ₄ AF is 22% or more, and iron A method for producing a Portland cement clinker, wherein the raw material ratio is adjusted so that the rate (IM) is 1.40 to 1.80.   A method for producing a Portland cement composition, wherein Portland cement clinker is obtained by the production method according to claim 1 and gypsum is added thereto.   Furthermore, the manufacturing method of the Portland cement composition of Claim 2 which adds 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.