KR100875447B1 - Method for producing cement with controlled interstitial phase of clinker - Google Patents

Abstract

Cement manufactured by using a gap phase of a controlled clinker is provided to reduce an exhaust of carbon dioxide, to save energy and to protect environment by reducing a fuel-used quantity and using lime stone having lower quality. Cement is manufactured by synthesizing a clinker of which a lime saturation factor(LSF) is 91 and an A/F ratio(aluminate to ferrite) is 0.15~0.30 or the LSF is 90 - 85, a silica modulus is over 2.5, an iron modulus is below 1.5 and the A/F ratio is 0.15~0.30. An SO3 content of the clinker is controlled to 0.5~1.0 weight%.

Description

Method for producing cement with controlled interstitial phase of clinker

The present invention relates to the production of cement, and more particularly, to reducing energy consumption and utilization of low-grade limestone to reduce carbon dioxide emissions and to achieve energy saving and environmental protection, and to manufacturing cement having functions desired by consumers. .

 Due to the highly developed industrialization, changes in the global atmospheric environment are accelerating, and accordingly, damage due to extreme weather is also increasing. Therefore, efforts are being made to reduce greenhouse gas emissions worldwide.

Cement industry is a representative energy consumption, carbon dioxide (CO ₂ ) A large amount of gas generated Industry CO ₂ gas generation process can be divided into CO ₂ generated from the coal and fuel substitutes on the combustion process and CO ₂ generated from raw materials. CO ₂ generation rate in the fuel and raw material in the process is ≒ 36%: the 64% level.

During the firing of raw mixes and the combustion of bituminous coal and alternatives, a large amount of CO ₂ gas is generated, which is closely related to the global warming that is currently emerging.

Therefore, various methods have been proposed to reduce the amount of CO ₂ gas generated in the cement manufacturing process. As a representative method

1) how to lower the firing temperature of cement clinker,

2) There is a method of applying mixed cement which can reduce the amount of clinker and finally reduce the firing.

However, these methods are not easily applied to the cement manufacturing process at present, because of their drawbacks.

Belite cement, which can be fired at low temperature, has a low early strength expression rate and has a long condensation effect (increasing construction air and construction cost), and mixed cement is also mixed material (slag, fly ash and other pozzolanic materials). As a result of the increase in the content of the (or the like), similar disadvantages to the Belite cements appear. Therefore, without the basic physical properties such as strength and the condensation of such a cement it is not resolved can not develop, use a new cement for general purposes can be reduced to CO _2.

Accordingly, the present invention aims to achieve energy saving and environmental protection by manufacturing cement of a new concept that can reduce CO ₂ emissions by reducing fuel consumption and utilizing low-grade limestone while simultaneously manufacturing cement having a function desired by consumers. do.

In addition, the present invention is to enable the low-temperature firing through the research and development of cement and mixed cements that can exhibit the same level of physical properties as Ordinary Portland cement (OPC), that is, to induce plasticity to reduce the amount of unit bituminous coal used. It is aimed at reducing and securing the technology capable of producing high quality clinker.

In addition, the present invention aims to reduce the amount of CO ₂ generated through the use of low-grade limestone and the reduction of limestone input by developing a new concept of cement.

In the study of the present inventors for achieving the above object, by adjusting the content ratio of the aluminate (mineral) and ferrite (mineral) to suit the physical properties, and appropriately adjusting the alkali content that can be contained in the clinker It was found that the cement can be produced to complete the present invention.

According to the present invention, there is provided a method for producing cement, which is prepared by the synthesis of lime saturation factor (LSF) 91 and aluminate / ferrite ratio (A / F) of 0.15 to 0.30.

According to the present invention, the LSF is 90-85, the silica modulus (SM) is 2.5 or more, the iron modulus (Irom Modulus: IM) is 1.5 or less, and the A / F ratio is 0.15-0.30 through the clinker synthesis. Provided is a method for producing cement, which is characterized in that it is manufactured.

In addition, according to the present invention, there is provided a method for producing cement, characterized in that the clinker is controlled by the SO ₃ content of 0.5 to 1.0% by weight.

The cement according to the present invention exhibits very good physical properties such as plasticity, flowability, late-age strength, and low overall carbon dioxide, and maintains a good tendency even at low temperature firing.

Hereinafter, the present invention will be described in detail.

In the present invention, the lime saturation factor (LSF = Lime Saturation Factor) is a ratio indicating that substantially what compound is produced in the Portland cement clinker. When the raw material mixture having a high degree of lime saturation is fired, since SiO ₂ is mostly C ₃ S, a crude steel clinker is obtained. However, since the high temperature is required to fire the raw material mixture having a high degree of lime saturation, the firing process is slower and it is not good because it becomes a clinker containing a lot of uncalcined CaO. In addition, as the degree of lime saturation is lowered, C ₂ S increases, thereby obtaining cement of long-term strength.

Iron modulus (IM = Iron Modulus) is a ratio indicating the quantitative relationship between aluminate and ferrite, and low ferrous material mixtures facilitate the formation of clinker even at low firing temperatures. When the iron ratio is low, the cement has a low C ₃ A and a high C ₄ AF, so that the initial strength is low, but the heat of hydration is small and the chemical resistance is large. On the contrary, the raw material mixture having a high iron ratio increases fuel consumption because it is difficult to fire, and hard hard clinker is generated, resulting in high energy consumption during grinding in a cement mill, resulting in higher production costs.

The silicic acid rate (SM = Silica Modulus) is used to express the quantitative relationship between acid groups, and the silicic acid rate is an important value that affects the mixture behavior and clinker quality in rotary kilns firing clinker. When the silicic acid ratio is increased, the firing of the raw material mixture becomes difficult, so that high temperature heat is required for firing, and fuel consumption increases. In addition, the strength expression is delayed because the cement which erodes the kiln's refractory material and calcined has a lot of C ₂ S.

The characteristics of clinker minerals are as follows.

Alite (C ₃ S) is used to decompose CaCO ₃ in the raw material to CaO and to maintain its firing temperature at 1450 ℃. In particular, C ₃ S is synthesized. CaO demand is the highest and synthesis temperature is the highest. Therefore, reducing the C ₃ S content by adjusting the raw modulus (Modulus) may have a CO ₂ reduction effect by reducing the cement production energy.

As the interstitial phase, the aluminate phase (C ₃ A) and the ferrite phase (C ₄ AF) are produced early in the clinkerization reaction and the hydration rate is fast and high but does not contribute significantly to the strength increase.

Belite (C ₂ S) has a slow hydration reaction rate, so the higher the strength of C ₂ S, the higher the late strength enhancement rate.Reducing the amount of CaCO _{3 in} the raw material decreases C ₃ S in the clinker and C ₂ S Increases.

Table 1 shows the production of cement clinker compounds.

Table 2 compares the properties of the major cement clinker minerals.

The cement according to the present invention is an improved cement to give more functionality to the currently produced one kind of ordinary portland cement, which is classified into one category if classified by the existing classification method. As a functional feature of cement, it is possible to increase the use of low-temperature calcined and low-grade limestone by increasing the content of belite (C ₂ S), a clinker component mineral, and to reduce CO ₂ gas generation by actively utilizing low-temperature calcined and low-grade limestone. have.

Hereinafter, the method of the present invention will be described.

EXAMPLE

Grinded sampled limestone (86% high-CaCO ₃ , 77% low-CaCO ₃ ) and other raw materials for basic experiments, the mixture is prepared according to the plain and 21 experimental combinations examined and each firing temperature (1450 ° C: 22 formulations, 1400 and 1350 ° C: 11 formulations), the plasticity and mineral composition content (C ₂ S) prepared by synthesizing clinker in a laboratory (LAB.) Were primarily analyzed.

※ Plain: Limestone CaCO ₃ 83.5%, LSF 94, SM 2.5

Experimental formulation: Limestone CaCO ₃ 82.5-80.5%, LSF 93-89, SM 2.4-3.0

Of the 22 blending groups, we selected the blending group that showed the best results through basic experiments and examined the effect of each element on the change of clinker and cement properties by arbitrarily adjusting the alkali content and aluminate / ferrite ratio.

Starting materials and subsidiary materials

 The sampled raw materials and subsidiary materials were pulverized based on 12% of 88㎛ residue through LAB.Ball Mill, and the chemical composition of each raw material and subsidiary materials was analyzed. The results are shown in Table 3.

A basic experiment

Prior to the comparison of cement properties, the mixing of possible mixtures by adjusting limestone grade and mixing modulus was carried out to compare and analyze the plasticity and mineral composition contents of LAB. The experiment was conducted primarily.

Raw material formulation and Clinker  synthesis

Limestone Grace (CaCO ₃ 82.5-80.5%) and IM (1.2-1.5) and clinker C ₂ S content based on pumice and F / A at 2% in the mixed modulus range (LSF 93-89, SM 2.4-3.0), respectively (25- Twenty-one combinations satisfying 35%, Bogue's equation) were obtained, and LAB. The high temperature Box Furnace (Lindberg Model 5124) was synthesized for 10 minutes at the maximum firing temperature of 1450 ° C for 10 minutes, and then quenched at 1350 ° C and quenched at room temperature. As a result of comparative analysis of 21 compound groups, limestone quality and mixing modulus of the selected optimal compound group were derived. The results are shown in Table 4.

Experiment result

The clinker characteristics of the selected formulations (SB-11, SB-15) were compared with plain. Table 5 and Table 6 show the raw material blending ratios and chemical composition analysis results for the plain and the experimental blending groups.

 In order to grasp the plasticity according to the change of A / F ratio, the plasticity according to IM change was identified while fixing SM and LSF affecting plasticity. (LSF 91, SM 2.6 fixed)

Table 7 shows the firing results (XRD quantitative analysis results) according to the change in the A / F ratio.

From the results of Table 7, the tendency of ovarianity according to the increase of IM was almost insignificant. As the firing temperature was decreased, the content of C ₃ A increased and the content of C ₄ AF decreased .

The contents of C ₃ A and C ₄ AF according to the firing temperature of the compound SB-11,15 determined in consideration of the C ₂ S content and the plasticity were compared.

Comparing the contents of the interstitial phases (C ₃ A, C ₄ AF), the contents of the total interstitial phases are almost similar (15-17%), and SB-15 has the highest C ₄ AF content while the C ₃ A content is This is due to the fact that clay input costs are the lowest and iron ore input costs are the highest in the mix of raw materials for modulus adjustment.

Table 8 shows the firing results according to the firing temperature change.

In the change of the interstitial phase in the clinker mineral phase with the firing temperature and residence time, it is generally known that as the firing temperature decreases and the residence time of the raw material in the kiln decreases, C ₃ A increases and C ₄ AF decreases. In this experiment, only the effects of the firing temperature (remaining time due to the synthesis of lab clinker is the same condition, excluding the effect of this part), the C ₃ A content increases and the C ₄ AF content decreases as the firing temperature decreases. It could be confirmed. The content of C ₃ A (aluminate) is generally one of the important factors influencing condensation and flowability rather than strength in cement.

Considering alkali content Raw Mix Modulus

Generally, in cement, alkali is present in the form of alkali sulphate (K ₂ SO ₄ ) in combination with sulfate ions (SO ₃ ) during clinker firing process or in the form of solid solution in clinker crystal to change the crystal structure of C ₃ A (Aluminate). do.

The alkali sulfate (K ₂ SO ₄ ) content has a significant effect on the cement paste fluidity. In general, as the cooling condition of the clinker increases to slow cooling, the amount of alkali dissolved in the clinker increases, indicating that the alkali sulfate content decreases.

Therefore, the fluidity was measured while changing the total alkali and SO ₃ content to determine the proper alkali content.

① Fluidity by changing alkali and SO ₃ content

㉮ Experimental method

The experimental mixture SB-11, 15 is different from the alkali content of the actual process because the raw materials were mixed and fired in the lab.

There is no fuel and no circulation of volatiles, resulting in lower K ₂ O and SO ₃ content than process clinkers. Thus LAB. Replacement of K ₂ O and SO ₃ won in consideration of the volatilization of scarce K ₂ O and SO ₃ won to similarly prepared K ₂ O and SO ₃ in the synthesis of clinker from the original process clinker so need to artificially supplemented with in Formulation procedure K ₂ SO ₄ reagent was used as a circle.

LAB. Considering the volatilization during firing, K ₂ O and SO ₃ of the actual process clinker To find a formulation similar to the content, K ₂ SO ₄ reagent was added in the range of 0.4-0.8%. As a result of the firing test, the K ₂ SO ₄ reagent when added to 0.6% to oehal actual process clinker of SO ₃ (0.7%), and K ₂ O as the closest appear to (0.91%) content of K ₂ SO ₄ reagent It was decided to add 0.6% by exhalation.

Table 9 shows changes in the amount of K ₂ SO ₄ addition suitable for alkali and SO ₃ of the actual process clinker.

㉯ Experimental results

The results of measuring the condensation of the blended group through the experimental blending are shown in Table 10. The settling time of the experimental group was found to be later than both plain and final. As the low temperature firing occurs, the initialization and termination are shortened, which is analyzed to have a different effect on the increase of C ₃ A content due to low temperature firing.

Lab that produces one kind of normal cement closer to two kinds of medium heat cement through the change of clinker mineral composition (C ₂ S content of 30-35%) according to the mixing modulus adjustment (LSF 86-90, SM 2.6-2.7). As a result of the experiment, the following conclusions were obtained.

First, the result of the measurement of the experimental formulation, clinker with a similar F-CaO content, that is, the level of LSF 91 and the ratio of Aluminate / Ferrite between 0.15 and 0.30.

Second, clinker which controlled Aluminate and Ferriteql to 0.15 ~ 0.30 when LSF is lowered to 90 ~ 85 and SM is set to 2.5 or more and IM is below 1.5.

Third, the cement developed by producing clinker with controlled SO ₃ content of 0.5 ~ 1.0 wt% in this clinker is excellent in most of physical properties such as plasticity, fluidity, and late age strength, and maintains overall good tendency even at low temperature firing. It was. It also showed better fluidity and similar settling time levels than regular OPC.

Claims (4)

Lime saturation factor (LSF) 91, alumina / ferrite ratio (A / F) is 0.15 ~ 0.30 by a clinker synthesis method characterized in that the manufacturing method of the cement. LSF is 90 ~ 85, silica modulus (SM) is more than 2.5, iron modulus (Irom Modulus: IM) is less than 1.5, A / F ratio of 0.15 ~ 0.30 characterized in that it is produced by clinker synthesis Method of manufacturing cement. delete The method for producing cement according to claim 1 or 2, wherein the SO ₃ content of the clinker is controlled to 0.5 to 1.0% by weight.