Peculiarities of Portland Cement Clinker Synthesis in the Presence of a Significant Amount of SO3 in a Raw Mix

*Oleg Sheshukov and Michael Mikheenkov*

## **Abstract**

Due to the depletion of the raw material base and a technogenic materials addition into a raw mix for the Portland cement clinker synthesis, sulfur and its oxides amount in a raw mix increases. According to literature the Portland cement clinker synthesis in the presence of a sulfur oxides significant amount is difficult. As the content of SO3 in the raw mix increases the amount of C2S increases while C3S and C3A amount decrease. With an equal total content of C2S and C3S in the clinker their ratio C3S/C2S decreases with an increased content of SO3. These factors lead to a deterioration in the Portland cement clinker quality. The clinker formation reactions thermodynamic analysis and some experimental studies allow determining reasons for the Portland cement clinker quality deterioration. It was found that the presence significant amount of a SO3 in the raw mix the synthesis in solid phase of low-basic C4A3 S (ye'elimite) is the thermodynamically preferred rather than highbasic C3A and C4AF. As a result, excess and crystallized free lime inhibits the C3S synthesis through the liquid phase. The experimental studies result helped to develop a methodology for calculating the composition of a raw mix from materials with significant amount of SO3. It allows to reduce the SO3 negative effect on the Portland cement clinker synthesis and to obtain high-quality Portland cement.

**Keywords:** high-sulfate raw material, Portland cement clinker, alite, belite, brownmillerite, ye'elimite, calculation procedure

## **1. Introduction**

Sulfur and its oxides in the form of sulfate and sulfide minerals appear in the raw mixture of Portland cement clinker with the main raw materials for the preparation of clinker, namely clay and carbonate rock as well as additives and fuel. The technogenic origin additives of the metallurgical and heat-power industry, namely slags, fly ashes and oil cokes have especially high concentration of sulfur compounds [1–3]. According to [4] sulfur with calcium oxide forms calcium sulfate CaSO4 under conditions of oxidative burning. Depending on the burning temperature the latter with the alkaline components of the raw mix forms alkaline metal sulfates or with clinker minerals forms sulfospurrit 2(C2S)C S and ye'elimite C4A3 S and participates in the alkali-sulfate cycle of the furnace.

When the SO3 content in the clinker is less than 2.0% it has a positive effect on the synthesis of Portland cement clinker since the alkali metal sulfates formed in its presence are effective melts that reduce the temperature of appearance of the liquid phase and its viscosity providing accelerated synthesis of clinker minerals [5, 6].

The positive role of SO3 in clinker is also evident when using a raw mixture with a significant content of alkalis. When the molar ratio of SO3/(Na2O+K2O) is close to 1, the excess alkali is removed from the raw material mixture due to the removal of alkali metal sulfates during heating [4, 6].

If the SO3 content in the clinker exceeds 2.0%, there are negative phenomena associated with both the quality of Portland cement clinker and its production technology.

According to [7, 8] when the content of SO3 in the raw mixture increases the amount of C2S increases, C3S decreases and when the total content of these phases in the clinker is equal, their C3S/C2S ratio decreases.

The samples were burnt at temperatures from 1100 to 1300 °C. The synthesized clinker was crushed to a residue on the sieve No. 008 no more than 5.0% and the sugar-glycerate method was used to determine the content of CaOfree in it. The phase composition of fully synthesized clinkers was determined by chemical and xray methods. Qualitative x-ray phase analysis was performed using an XRD-7000 diffractometer (Shimadzu). Quantitative x-ray phase analysis was performed using a STADI-P diffractometer (STOE, Germany). The shooting was made under CuKαradiation (40 kV, 30 mA), with graphite monochromator, in the range of scattering angles 2Θ = 10–70 deg., with a step of 0.02 deg. and an excerpt of 2 s. The results were analyzed using the PDF-2 database (Release 2008 RDB 2.0804). Thermal analysis (TA) of hydration products was performed using the DSC method (differential scanning calorimetry) on the STA 449 F3 Jupiter thermal analyzer (Netzsch-Geratebau GmbH). The temperature varied from room temperature (approximately 20°C) to 800°C at a heating rate of 10°C/min. The samples of the hydration products prepared by a grinding of synthesized clinker and on their basis cement paste prepared. The size of cement pastes were 20 x 20 x 20 mm, which were prepared under the condition of water: cement ratio of 0.4. After preparation, all samples were placed in box with water at temperature of 20°C. In a box samples were maintained 28 day before full hydration. Chemical analysis of cement was performed in accordance with the requirements of Russian Standard 5382–91. For reception of micro-photos the optical microscope Olympus GX-51 (Japan) was used. Samples of clinker was polished and their surface was etching by Nital [11]. After this procedure alite was painted in green-violet color, and belite in light

**Material CaO SiO2 Al2O3 Fe2O3 SO3 MgO LOI Total** Limestone (CaCO3) 56.35 0.04 0.06 0.04 0.03 0.37 42.8 99.69 Clay 1.21 50.70 19.90 11.80 0 1.40 14.81 99.90 Quartz sand 0.03 98.80 0.45 0.03 0 0 0.13 99.40 Natural gypsum 32.02 0.80 0.45 0.23 44.50 0 22.0 100.0 Clinker without gypsum 67.17 22.19 6.08 3.59 0.035 0.85 0 99.99 Clinker with gypsum 65.25 21.12 5.80 3.42 2.26 0.80 1.1 99.99

*Peculiarities of Portland Cement Clinker Synthesis in the Presence of a Significant Amount…*

The chemical composition of raw materials and clinker is shown in **Table 1**.

The results of qualitative phase analysis of clinker based on a raw mix with the

The content of free lime in a clinker based on a raw mix with the addition of 5%

Analysis of the data presented in **Figures 1** and **2** and **Table 2** shows that the introduction of 5% gypsum into the raw mix suppresses the alite formation and contributes to the formation of a significant amount of free lime in the clinker. The diffraction peaks which are typical for free lime are present in a clinker based on a raw mix with the addition of 5% gypsum burnt at a temperature of 1300°C and the diffraction peaks which are typical for alite are not fixed at this temperature.

brown color.

**87**

**Table 1.**

**3. Experimental results and discussion**

*The chemical composition of raw materials and clinker, mass %.*

*DOI: http://dx.doi.org/10.5772/intechopen.94915*

addition of 5% gypsum are shown in **Figure 1**. **Figure 2** shows a micrograph of clinker.

gypsum is shown in **Table 2**.

Since alite (C3S) is the most active and refractory component of Portland cement clinker the alite reduction leads to a decrease of the clinker refractoriness and activity. A decrease of the clinker refractoriness appears in the formation of rings in the furnace and incrustation in the calcinators cyclones and a decrease in activity shows in the drop in the strength of Portland cement.

It was found [9, 10] that not only the C3S content but also C3A content decrease in high-sulfate clinker. The reason for the decrease in the C3A content in highsulfate clinker is the isomorphic substitution of silicon for aluminum in silicate phases.

The reasons for the decrease of alite (C3S) content in Portland cement clinker with an increase of SO3 content in it are not found in the literature.

The main purpose of this study is to determine the reasons for the SO3 negative impact on the Portland cement clinker synthesis and to develop a method to prevent it.

To achieve this goal, it is needed to:


## **2. Materials and experiment methods**

Raw mixtures were burnt to produce Portland cement clinker with following modular characteristics: LSF = 0.92, n = 2.3 and p = 1.69. For the preparation of Portland cement clinker a raw mix based on limestone, clay, quartz sand and natural gypsum was used. When preparing the raw mix the composition was modeled by the introduction of gypsum into the raw mix with raw components in the ratio: raw mix/gypsum = 95/5%, to achieve SO3 in the raw mix of more than 2.0%. The raw mix was homogenized in a laboratory mill by joint grinding of raw components and gypsum for 30 minutes. The homogeneous mixture was moistened and pressed at a pressure of 50 MPa.


*Peculiarities of Portland Cement Clinker Synthesis in the Presence of a Significant Amount… DOI: http://dx.doi.org/10.5772/intechopen.94915*

#### **Table 1.**

When the SO3 content in the clinker is less than 2.0% it has a positive effect on the synthesis of Portland cement clinker since the alkali metal sulfates formed in its presence are effective melts that reduce the temperature of appearance of the liquid phase and its viscosity providing accelerated synthesis of clinker minerals [5, 6]. The positive role of SO3 in clinker is also evident when using a raw mixture with a significant content of alkalis. When the molar ratio of SO3/(Na2O+K2O) is close to 1, the excess alkali is removed from the raw material mixture due to the removal

*Cement Industry - Optimization, Characterization and Sustainable Application*

If the SO3 content in the clinker exceeds 2.0%, there are negative phenomena associated with both the quality of Portland cement clinker and its production

According to [7, 8] when the content of SO3 in the raw mixture increases the amount of C2S increases, C3S decreases and when the total content of these phases

Since alite (C3S) is the most active and refractory component of Portland cement

It was found [9, 10] that not only the C3S content but also C3A content decrease

The reasons for the decrease of alite (C3S) content in Portland cement clinker

The main purpose of this study is to determine the reasons for the SO3 negative

• determine the reasons for the SO3 negative influence on the Portland cement

Raw mixtures were burnt to produce Portland cement clinker with following modular characteristics: LSF = 0.92, n = 2.3 and p = 1.69. For the preparation of Portland cement clinker a raw mix based on limestone, clay, quartz sand and natural gypsum was used. When preparing the raw mix the composition was modeled by the introduction of gypsum into the raw mix with raw components in the ratio: raw mix/gypsum = 95/5%, to achieve SO3 in the raw mix of more than 2.0%. The raw mix was homogenized in a laboratory mill by joint grinding of raw components and gypsum for 30 minutes. The homogeneous mixture was moistened

clinker the alite reduction leads to a decrease of the clinker refractoriness and activity. A decrease of the clinker refractoriness appears in the formation of rings in the furnace and incrustation in the calcinators cyclones and a decrease in activity

in high-sulfate clinker. The reason for the decrease in the C3A content in highsulfate clinker is the isomorphic substitution of silicon for aluminum in silicate

impact on the Portland cement clinker synthesis and to develop a method to

with an increase of SO3 content in it are not found in the literature.

of alkali metal sulfates during heating [4, 6].

in the clinker is equal, their C3S/C2S ratio decreases.

shows in the drop in the strength of Portland cement.

To achieve this goal, it is needed to:

• perform thermodynamic calculations;

**2. Materials and experiment methods**

and pressed at a pressure of 50 MPa.

**86**

• develop methods to prevent that negative impact.

• conduct experimental research;

• analyze literary sources;

clinker synthesis;

technology.

phases.

prevent it.

*The chemical composition of raw materials and clinker, mass %.*

The samples were burnt at temperatures from 1100 to 1300 °C. The synthesized clinker was crushed to a residue on the sieve No. 008 no more than 5.0% and the sugar-glycerate method was used to determine the content of CaOfree in it. The phase composition of fully synthesized clinkers was determined by chemical and xray methods. Qualitative x-ray phase analysis was performed using an XRD-7000 diffractometer (Shimadzu). Quantitative x-ray phase analysis was performed using a STADI-P diffractometer (STOE, Germany). The shooting was made under CuKαradiation (40 kV, 30 mA), with graphite monochromator, in the range of scattering angles 2Θ = 10–70 deg., with a step of 0.02 deg. and an excerpt of 2 s. The results were analyzed using the PDF-2 database (Release 2008 RDB 2.0804). Thermal analysis (TA) of hydration products was performed using the DSC method (differential scanning calorimetry) on the STA 449 F3 Jupiter thermal analyzer (Netzsch-Geratebau GmbH). The temperature varied from room temperature (approximately 20°C) to 800°C at a heating rate of 10°C/min. The samples of the hydration products prepared by a grinding of synthesized clinker and on their basis cement paste prepared. The size of cement pastes were 20 x 20 x 20 mm, which were prepared under the condition of water: cement ratio of 0.4. After preparation, all samples were placed in box with water at temperature of 20°C. In a box samples were maintained 28 day before full hydration. Chemical analysis of cement was performed in accordance with the requirements of Russian Standard 5382–91. For reception of micro-photos the optical microscope Olympus GX-51 (Japan) was used. Samples of clinker was polished and their surface was etching by Nital [11]. After this procedure alite was painted in green-violet color, and belite in light brown color.

The chemical composition of raw materials and clinker is shown in **Table 1**.

## **3. Experimental results and discussion**

The results of qualitative phase analysis of clinker based on a raw mix with the addition of 5% gypsum are shown in **Figure 1**.

**Figure 2** shows a micrograph of clinker.

The content of free lime in a clinker based on a raw mix with the addition of 5% gypsum is shown in **Table 2**.

Analysis of the data presented in **Figures 1** and **2** and **Table 2** shows that the introduction of 5% gypsum into the raw mix suppresses the alite formation and contributes to the formation of a significant amount of free lime in the clinker. The diffraction peaks which are typical for free lime are present in a clinker based on a raw mix with the addition of 5% gypsum burnt at a temperature of 1300°C and the diffraction peaks which are typical for alite are not fixed at this temperature.

reduces its refractoriness and contributes to the appearance of a melt at tempera-

*Peculiarities of Portland Cement Clinker Synthesis in the Presence of a Significant Amount…*

The formation of a significant amount of free lime in the clinker during the decomposition of gypsum is unlikely because with the stoichiometric ratio of CaO and SO3 in gypsum anhydrite, respectively 41.19% and 58.81%, 2.06% of CaOfree can be formed from the decomposition of 5.0% of gypsum and according to the data presented in **Table 2**, more than 11% of CaOfree is formed at a temperature of 1300°C. To determine the reasons for the appearance of a significant amount of free lime in a high-sulfate clinker a thermodynamic analysis of the reactions of C3A and C4AF formation was performed according to the data of [12] as well the reactions of C4A3 S

tures below the temperatures of Portland cement clinker synthesis.

*DOI: http://dx.doi.org/10.5772/intechopen.94915*

formation presented in [13]. The analysis results are presented in **Table 3**.

solid-phase synthesis but from a melt.

**Table 3.**

**89**

*reaction C4A3* S *according to data of [13].*

minerals, free lime can be formed in the clinker by reactions:

According to the data presented in **Table 4**, the synthesis of C3A and C4AF in a low-sulfate clinker is thermodynamically possible from the simple minerals, namely CaO, Al2O3 and Fe2O3 (reactions No. 1–2). In a high-sulfate clinker, reaction of the formation of ye'elimite C4A3S (reaction No. 3) is thermodynamically preferable since the free Gibbs energy of it is more negative than that of reactions No. 1 and 2. There are different opinions about the formation mechanism of ye'elimite C4A3S in clinker during heating. According to [13] the synthesis of ye'elimite due to an excess of lime at the time of its formation begins with the formation of mayenite according to the scheme C12A7 ! CA ! C3A3CS. According to our data [14] in the pressed raw mix due to its higher reaction ability the synthesis of ye'elimite proceeds according to the scheme CA2 ! CA ! C2A2 ! C3A3 ! C3A3C S with the formation of calcium monoaluminate (CA) at temperatures about 700°C and its presence throughout the burning temperature range up to 1300°C. In the presence of calcium monoaluminate the formation of C3A and C4AF is thermodynamically impossible (reactions No. 4–6). Based on these studies the authors of [12] concluded that in the presence of calcium monoaluminate C3A and C4AF are formed not in

Therefore if the calculation of the raw mix is carried out according to the usual scheme for the formation of C3A and C4AF minerals in a high-sulfate clinker, and in fact in a high-sulfate clinker low-base aluminates and calcium ferrites are formed before the melt appears, then due to the difference in the lime content in these

4CaO þ Al2O3 þ Fe2O3 ! СaO � Al2O3 þ СaO � Fe2O3 þ 2CaO*:* (2)

**No. Reactions The value of ΔGo, kJ/mol at**

1 3CaO + Al2O3 = 3CaO�Al2O3 �17.0 �41.8 �47.0 �52.9 �55.7 2 4CaO + Al2O3 + Fe2O3 = 4CaO�Al2O3�Fe2O3 �49.3 �64.9 �64.1 �60.83 �58.1 3 3CaO + 3Al2O3 + CaSO4 = 3CaO�3Al2O3�CaSO4 �99.1 �445.1 �583.6 �758.9 �853.5 4 CaO�Al2O3 + 2CaO = 3CaO�Al2O3 +33.7 +32.3 +31.7 +33.26 +34.4 5 CaO�Al2O3 + CaO + 2CaO�Fe2O3 = 4CaO�Al2O3�Fe2O3 +10.4 +39.7 +49.0 +60.3 +66.2 6 CaO�Al2O3 + 2CaO + CaO�Fe2O3 = 4CaO�Al2O3�Fe2O3 +42.4 +72.1 +79.77 +79.8 +83.7

*Thermodynamic analysis of formation reactions C3A and C4AF according to data of [12] and formation*

3CaO þ Al2O3 ! СaO � Al2O3 þ 2CaO, (1)

**temperature, K 298 1023 1200 1400 1500**

#### **Figure 1.**

*The results of qualitative phase analysis of clinker based on a raw mix with the addition of 5% gypsum.*

#### **Figure 2.**

*A micrograph of clinker based on a raw mix with the addition of 5% gypsum.*


#### **Table 2.**

*The content of free lime in a clinker.*

Clinker completely melts when it is heated to a temperature of 1350°C. Analysis of the melt heated to a temperature of 1600°C indicates that alite is formed during this overheating but there is 6.2% free lime in the clinker.

The reason for suppressing the alite formation in a high-sulfate clinker is likely the formation of a well-crystallized CaOfree which is not soluble in the liquid phase, does not interact with C2S and does not form C3S. The absence of alite in the clinker

### *Peculiarities of Portland Cement Clinker Synthesis in the Presence of a Significant Amount… DOI: http://dx.doi.org/10.5772/intechopen.94915*

reduces its refractoriness and contributes to the appearance of a melt at temperatures below the temperatures of Portland cement clinker synthesis.

The formation of a significant amount of free lime in the clinker during the decomposition of gypsum is unlikely because with the stoichiometric ratio of CaO and SO3 in gypsum anhydrite, respectively 41.19% and 58.81%, 2.06% of CaOfree can be formed from the decomposition of 5.0% of gypsum and according to the data presented in **Table 2**, more than 11% of CaOfree is formed at a temperature of 1300°C.

To determine the reasons for the appearance of a significant amount of free lime in a high-sulfate clinker a thermodynamic analysis of the reactions of C3A and C4AF formation was performed according to the data of [12] as well the reactions of C4A3 S formation presented in [13]. The analysis results are presented in **Table 3**.

According to the data presented in **Table 4**, the synthesis of C3A and C4AF in a low-sulfate clinker is thermodynamically possible from the simple minerals, namely CaO, Al2O3 and Fe2O3 (reactions No. 1–2). In a high-sulfate clinker, reaction of the formation of ye'elimite C4A3S (reaction No. 3) is thermodynamically preferable since the free Gibbs energy of it is more negative than that of reactions No. 1 and 2.

There are different opinions about the formation mechanism of ye'elimite C4A3S in clinker during heating. According to [13] the synthesis of ye'elimite due to an excess of lime at the time of its formation begins with the formation of mayenite according to the scheme C12A7 ! CA ! C3A3CS. According to our data [14] in the pressed raw mix due to its higher reaction ability the synthesis of ye'elimite proceeds according to the scheme CA2 ! CA ! C2A2 ! C3A3 ! C3A3C S with the formation of calcium monoaluminate (CA) at temperatures about 700°C and its presence throughout the burning temperature range up to 1300°C. In the presence of calcium monoaluminate the formation of C3A and C4AF is thermodynamically impossible (reactions No. 4–6). Based on these studies the authors of [12] concluded that in the presence of calcium monoaluminate C3A and C4AF are formed not in solid-phase synthesis but from a melt.

Therefore if the calculation of the raw mix is carried out according to the usual scheme for the formation of C3A and C4AF minerals in a high-sulfate clinker, and in fact in a high-sulfate clinker low-base aluminates and calcium ferrites are formed before the melt appears, then due to the difference in the lime content in these minerals, free lime can be formed in the clinker by reactions:

$$\text{\bf{3CaO}} + \text{Al}\_2\text{O}\_3 \rightarrow \text{CaO} \cdot \text{Al}\_2\text{O}\_3 + \text{2CaO},\tag{1}$$

$$\text{4CaO} + \text{Al}\_2\text{O}\_3 + \text{Fe}\_2\text{O}\_3 \rightarrow \text{CaO} \cdot \text{Al}\_2\text{O}\_3 + \text{CaO} \cdot \text{Fe}\_2\text{O}\_3 + 2\text{CaO}.\tag{2}$$


#### **Table 3.**

*Thermodynamic analysis of formation reactions C3A and C4AF according to data of [12] and formation reaction C4A3* S *according to data of [13].*

Clinker completely melts when it is heated to a temperature of 1350°C. Analysis of the melt heated to a temperature of 1600°C indicates that alite is formed during this

**Material The content of free lime in a clinker,**

**mass %, at the burning temperature, <sup>о</sup>**

**1100 1200 1300**

14.0 13.84 11.6

**С**

*The results of qualitative phase analysis of clinker based on a raw mix with the addition of 5% gypsum.*

*Cement Industry - Optimization, Characterization and Sustainable Application*

The reason for suppressing the alite formation in a high-sulfate clinker is likely the formation of a well-crystallized CaOfree which is not soluble in the liquid phase, does not interact with C2S and does not form C3S. The absence of alite in the clinker

overheating but there is 6.2% free lime in the clinker.

Clinker based on a raw mix with the addition of 5%

*A micrograph of clinker based on a raw mix with the addition of 5% gypsum.*

**Figure 1.**

**Figure 2.**

gypsum

*The content of free lime in a clinker.*

**Table 2.**

**88**

Free lime begins to accumulate in the clinker from the decomposition beginning temperature of calcium carbonate to the appearance of the liquid phase due to the difference in the lime content in the tricalcium aluminate C3A accepted in calculation and actually formed calcium monoaluminate CA. Totally because of gypsum decomposition and the difference between the limes content in the calcium aluminates, well-crystallized free lime in an amount of about 5% can be formed in the clinker from the decomposition beginning temperature of calcium carbonate until the appearance of the liquid phase, and this amount is sufficient to suppress the alite formation when the liquid phase appears.

Factors in the given formula are taken from phase diagram CaO-Al2O3-SiO2 and CaO-Al2O3-SiO2-Fe2O3 at optimum relationship oxides providing absence free lime in clinker. If to use Kinda V.A's design procedure [16], that the formula (8) becomes

*Peculiarities of Portland Cement Clinker Synthesis in the Presence of a Significant Amount…*

2, 8SiO2 þ 1, 65Al2O3 þ 0, 35Fe2O3 þ 0, 7SO3

For calculation degree of saturation (DS) of clinker metastable minerals by sulphate in the presence of gypsum Atakuziev T.A.'s formula [18] is used considering that sulfatization C2S, CA in clinker is possible. Taking into account the given

> DS <sup>¼</sup> SO3 � 0, 261Al2O3 0, 667SiO2

At DS = 0 C3A3C S will be formed in the raw mix and at DS = 1 sulfosporite

**4. Example of calculation of high-sulphate raw material mixture No. 1**

**Table 4** shows the calculated composition of the raw mix and the chemical

At the second stage a typical Portland cement clinker with modular characteristics LSF = 0.92, n = 2.3, p = 1.7 is calculated on the basis of clinker after decomposition of gypsum as one of the components of the raw mix and corrective additives:

The calculated composition of the raw mix for obtaining Portland cement clin-

Finally the composition of the raw mix is calculated by multiplying the quantity

CaCO3 ¼ ð Þþ 71*:*31x0*:*633 30*:*7 ¼ 75*:*8%; (11)

Clay ¼ 25*:*71х0*:*633 ¼ 16*:*3%; (12)

of raw components of the clinker shown in **Table 4** by the quantity of clinker shown in **Table 5**, and is summed up with the quantity of raw components shown in

with the modular characteristics LSF = 1 and DS = 0. At DS = 0 calcium sulfoaluminate C3A3C S can be formed in the raw mix based on calcium

composition of clinkers before and after the gypsum decomposition.

ker and it's chemical composition is shown in **Table 5**.

At the first stage on the basis of raw components the chemical composition of which is shown in **Table 1** the raw mix of high-sulphate clinker is calculated for the synthesis of calcium monoaluminate in it according to the formulas (9) and (10)

At the second stage the calculation of the synthesis of alite Portland cement with the required modular characteristics is made. It is assumed that when the liquid phase appears the gypsum is completely decomposed by the reaction 6 and the chemical composition of the clinker formed after gypsum decomposition is considered to be the chemical composition of one of the raw mix components. Other components of the raw mix are limestone and a corrective additive – quartz sand. At the second stage the saturation coefficient (LSF) is calculated using the formula (9) but only for the synthesis of tricalcium aluminate 3CaO�Al2O3 in the clinker (the

*:* (9)

*:* (10)

LSF <sup>¼</sup> CaO

updating the formula DS calculation looks as follows:

full analogue of the formula (7):

*DOI: http://dx.doi.org/10.5772/intechopen.94915*

2(C2S)С S will also be formed.

coefficient for Al2O3 is 1.65).

monoaluminate.

**Table 5**:

**91**

limestone and quartz sand.

Since the alite formation in clinker is suppressed and only belite is formed, so due to the difference in the lime content in these minerals the total content of free lime at the synthesis completion temperatures is already about 11%. When the melt temperature rises up to 1600 <sup>о</sup> С a small amount of alite is formed but the CaOfree however does not dissolve and is remained in an amount of about 6%.

To prevent the formation of CaOfree in high-sulfate clinker it is proposed to calculate the raw mix of Portland cement clinker in accordance with our patent [15] in two stages. At the first stage the calculation of calcium monoaluminate CaO�Al2O3 synthesis in a high-sulphate clinker is made, meanwhile during burning intermediate metastable phase – ye'elimite C4A3 S will form in a high-sulphate clinker. It decays when the liquid phase appears.

Since the formation of high-base phases is thermodynamically more likely when a liquid phase occurs, and C3A and C4AF can only be formed from low-base phases if free lime is present by reactions:

$$\text{CaO} \cdot \text{Al}\_2\text{O}\_3 + 2\text{CaO} \rightarrow \text{3CaO} \cdot \text{Al}\_2\text{O}\_3,\tag{3}$$

$$\text{CaO} \cdot \text{Al}\_2\text{O}\_3 + \text{CaO} \cdot \text{Fe}\_2\text{O}\_3 + 2\text{CaO} \rightarrow 4\text{CaO} \cdot \text{Al}\_2\text{O}\_3 \cdot \text{Fe}\_2\text{O}\_3. \tag{4}$$

At a burning temperature of about 1300°C in the absence of CaOfree its source can only be the reaction of converting alite to belite and the decomposition of calcium sulfate by reactions:

$$\text{\color{red}{3}C \text{a}O} \cdot \text{SiO}\_2 \to \text{2CaO} \cdot \text{SiO}\_2 + \text{CaO},\tag{5}$$

$$\text{2CaSO}\_4 \rightarrow \text{2CaO} + \text{2SO}\_2\uparrow + \text{O}\_2\uparrow. \tag{6}$$

Since it is possible to convert alite to belite in a high-sulphate clinker by reaction 5, the calculation of the raw mix at the first stage is made for the formation of the maximum amount of alite in it which is possible at SC = 1. The calculation of the saturation coefficient of the raw mix by lime at the first stage is made using the well-known formula of Kinda V.A. [16] with SC = 1 for the formation of CA in the clinker (the coefficient for Al2O3 is 0.55):

$$\text{SC} = \frac{\text{CaO} - 0, \text{55Al}\_2\text{O}\_3 - 0, \text{35Fe}\_2\text{O}\_3 - 0, \text{7SO}\_3}{2, \text{8SiO}\_2}. \tag{7}$$

At a conclusion of this formula are used molar parities CaO, Al2O3, Fe2O3 and SiO2 at formation in clinker the basic clinker minerals C3S, C2S, C3A and C4AF.

English analogue of the formula given is the formula for calculation LSF [17]:

$$\text{LSF} = \frac{\text{CaO}}{\text{2, 8SiO}\_2 + \text{1, 2Al}\_2\text{O}\_3 + \text{0, 65Fe}\_2\text{O}\_3}. \tag{8}$$

*Peculiarities of Portland Cement Clinker Synthesis in the Presence of a Significant Amount… DOI: http://dx.doi.org/10.5772/intechopen.94915*

Factors in the given formula are taken from phase diagram CaO-Al2O3-SiO2 and CaO-Al2O3-SiO2-Fe2O3 at optimum relationship oxides providing absence free lime in clinker. If to use Kinda V.A's design procedure [16], that the formula (8) becomes full analogue of the formula (7):

$$\text{LSF} = \frac{\text{CaO}}{2,8\text{SiO}\_2 + 1,65\text{Al}\_2\text{O}\_3 + 0,35\text{Fe}\_2\text{O}\_3 + 0,7\text{SO}\_3}.\tag{9}$$

For calculation degree of saturation (DS) of clinker metastable minerals by sulphate in the presence of gypsum Atakuziev T.A.'s formula [18] is used considering that sulfatization C2S, CA in clinker is possible. Taking into account the given updating the formula DS calculation looks as follows:

$$\text{DS} = \frac{\text{SO}\_3 - 0, 2\text{61}\text{Al}\_2\text{O}\_3}{0, 667 \text{SiO}\_2}. \tag{10}$$

At DS = 0 C3A3C S will be formed in the raw mix and at DS = 1 sulfosporite 2(C2S)С S will also be formed.

At the second stage the calculation of the synthesis of alite Portland cement with the required modular characteristics is made. It is assumed that when the liquid phase appears the gypsum is completely decomposed by the reaction 6 and the chemical composition of the clinker formed after gypsum decomposition is considered to be the chemical composition of one of the raw mix components. Other components of the raw mix are limestone and a corrective additive – quartz sand. At the second stage the saturation coefficient (LSF) is calculated using the formula (9) but only for the synthesis of tricalcium aluminate 3CaO�Al2O3 in the clinker (the coefficient for Al2O3 is 1.65).

## **4. Example of calculation of high-sulphate raw material mixture No. 1**

At the first stage on the basis of raw components the chemical composition of which is shown in **Table 1** the raw mix of high-sulphate clinker is calculated for the synthesis of calcium monoaluminate in it according to the formulas (9) and (10) with the modular characteristics LSF = 1 and DS = 0. At DS = 0 calcium sulfoaluminate C3A3C S can be formed in the raw mix based on calcium monoaluminate.

**Table 4** shows the calculated composition of the raw mix and the chemical composition of clinkers before and after the gypsum decomposition.

At the second stage a typical Portland cement clinker with modular characteristics LSF = 0.92, n = 2.3, p = 1.7 is calculated on the basis of clinker after decomposition of gypsum as one of the components of the raw mix and corrective additives: limestone and quartz sand.

The calculated composition of the raw mix for obtaining Portland cement clinker and it's chemical composition is shown in **Table 5**.

Finally the composition of the raw mix is calculated by multiplying the quantity of raw components of the clinker shown in **Table 4** by the quantity of clinker shown in **Table 5**, and is summed up with the quantity of raw components shown in **Table 5**:

$$\text{CaCO}\_3 = (71.31 \text{x}0.63 \text{\AA}) + \text{30.7} = 75.89 \text{\AA};\tag{11}$$

$$\text{Clay} = \text{25.71x0.633} = \text{16.396};\tag{12}$$

Free lime begins to accumulate in the clinker from the decomposition beginning temperature of calcium carbonate to the appearance of the liquid phase due to the

Since the alite formation in clinker is suppressed and only belite is formed, so due to the difference in the lime content in these minerals the total content of free lime at the synthesis completion temperatures is already about 11%. When the melt

To prevent the formation of CaOfree in high-sulfate clinker it is proposed to calculate the raw mix of Portland cement clinker in accordance with our patent [15]

CaO�Al2O3 synthesis in a high-sulphate clinker is made, meanwhile during burning intermediate metastable phase – ye'elimite C4A3 S will form in a high-sulphate

Since the formation of high-base phases is thermodynamically more likely when a liquid phase occurs, and C3A and C4AF can only be formed from low-base phases

CaO � Al2O3 þ CaO � Fe2O3 þ 2CaO ! 4CaO � Al2O3 � Fe2O3*:* (4)

At a burning temperature of about 1300°C in the absence of CaOfree its source can only be the reaction of converting alite to belite and the decomposition of

Since it is possible to convert alite to belite in a high-sulphate clinker by reaction 5, the calculation of the raw mix at the first stage is made for the formation of the maximum amount of alite in it which is possible at SC = 1. The calculation of the saturation coefficient of the raw mix by lime at the first stage is made using the well-known formula of Kinda V.A. [16] with SC = 1 for the formation of CA in the

> SC <sup>¼</sup> CaO � 0, 55Al2O3 � 0, 35Fe2O3 � 0, 7SO3 2, 8SiO2

English analogue of the formula given is the formula for calculation LSF [17]:

2, 8SiO2 þ 1, 2Al2O3 þ 0, 65Fe2O3

At a conclusion of this formula are used molar parities CaO, Al2O3, Fe2O3 and SiO2 at formation in clinker the basic clinker minerals C3S, C2S, C3A

LSF <sup>¼</sup> CaO

С a small amount of alite is formed but the CaOfree

CaO � Al2O3 þ 2CaO ! 3CaO � Al2O3, (3)

3CaO � SiO2 ! 2CaO � SiO2 þ CaO, (5) 2CaSO4 ! 2CaO þ 2SO2↑ þ O2↑*:* (6)

*:* (7)

*:* (8)

difference in the lime content in the tricalcium aluminate C3A accepted in calculation and actually formed calcium monoaluminate CA. Totally because of gypsum decomposition and the difference between the limes content in the calcium aluminates, well-crystallized free lime in an amount of about 5% can be formed in the clinker from the decomposition beginning temperature of calcium carbonate until the appearance of the liquid phase, and this amount is sufficient to suppress

*Cement Industry - Optimization, Characterization and Sustainable Application*

however does not dissolve and is remained in an amount of about 6%.

in two stages. At the first stage the calculation of calcium monoaluminate

the alite formation when the liquid phase appears.

clinker. It decays when the liquid phase appears.

temperature rises up to 1600 <sup>о</sup>

if free lime is present by reactions:

calcium sulfate by reactions:

and C4AF.

**90**

clinker (the coefficient for Al2O3 is 0.55):


#### **Table 4.**

*The calculated composition of the raw mix and the chemical composition of clinkers before and after the gypsum decomposition.*


**Table 5.**

*The calculated composition of the raw mix for obtaining alite Portland cement clinker and its chemical composition.*

$$\text{SiO}\_2 = \text{€}\,\text{0@t};\tag{13}$$

$$\text{Gypsum} = 2,98x0,633 = 1,9796. \tag{14}$$

The actual gypsum content after the introduction of corrective additives will decrease by:

$$\text{Gypsum} = 2.98 - 1,97 = 1.0196. \tag{15}$$

Then the quantity of corrective additives is calculated. The quantity of corrective additives is equal to the difference between the quantity of raw components calculated using the formulas (11)–(14) and the quantity of raw components calculated at the first stage and shown in **Table 4**.

The quantity of corrective additives is equal to:

$$\text{CaCO}\_3 = 75.8 - 71.31 = 4.49\%;\tag{16}$$

$$\text{Clay} = \text{16.3} - 25.71 = -9.496; \tag{17}$$

$$\text{SiO}\_2 = \text{€}\,\text{.0} - \text{0} = \text{€}\,\text{.0}\%.\tag{18}$$

Diffraction peak with d = 1.76 Å which is typical for C3S, increases up to a temperature of 1250°C and decreases starting from a temperature of 1250°C. The diffraction peak with d = 2.28 Å which is typical for C2S on the contrary decreases to a temperature of 1250°C and increases at temperatures above of 1250°C which indicates the transformation of alite part into belite according to Eq. (5). The intensity of the diffraction maximum with d = 3.72 Å which is typical for C3A3CS, decreases above the temperature of 1150°C, which indicates the decomposition of

*The change in the intensity of the diffraction maxima of the main phases of the clinker prepared in accordance with the correction calculation No. 1 and burnt at temperatures of 1150, 1200, 1250 and 1300°C.*

*The data of qualitative phase analysis of clinker prepared in accordance with correction calculation No. 1 and*

*Peculiarities of Portland Cement Clinker Synthesis in the Presence of a Significant Amount…*

CaSO4 in accordance with the reaction (6) and decay as a result.

**Figure 3.**

**Figure 4.**

**93**

*burnt at temperatures of 1150, 1200, 1250 and 1300°C.*

*DOI: http://dx.doi.org/10.5772/intechopen.94915*

A negative value for the clay amount means that it should be reduced.

**Figure 3** shows the data of qualitative phase analysis of clinker prepared in accordance with correction calculation No. 1 and burnt at temperatures of 1150, 1200, 1250 and 1300°C.

X-ray analysis indicates the absence of CaOfree in a clinker prepared in accordance with corrective calculations No. 1, at a burning temperature of 1200°C or higher. Stable alite in such clinker is formed already at the burning temperature of 1250°C as evidenced by the appearance of diffraction maxima with d = 1.76 Å and d = 3.04 Å which are typical for alite at this temperature. The change in the intensity of the diffraction maxima of the main phases of the clinker prepared in accordance with the correction calculation No. 1 and burnt at temperatures of 1150, 1200, 1250 and 1300°C is shown in **Figure 4**.

*Peculiarities of Portland Cement Clinker Synthesis in the Presence of a Significant Amount… DOI: http://dx.doi.org/10.5772/intechopen.94915*

#### **Figure 3.**

SiO2 ¼ 6*:*0%; (13)

**SiO2 CaO SiO2 Al2O3 Fe2O3 SO3 Total**

**CaO SiO2 Al2O3 Fe2O3 SO3 Total**

71.31 25.71 2.98 64.66 20.39 8.06 4.79 2.1 100

71.31 25.71 2.98 66.05 20.83 8.23 4.89 0 100

Gypsum ¼ 2, 98х0, 633 ¼ 1, 97%*:* (14)

30.7 63.3 6.0 68.2 22.1 6.1 3.6 0 100

Gypsum ¼ 2*:*98 � 1, 97 ¼ 1*:*01%*:* (15)

CaCO3 ¼ 75*:*8 � 71*:*31 ¼ 4*:*49%; (16) Clay ¼ 16*:*3 � 25*:*71 ¼ �9*:*4%; (17) SiO2 ¼ 6*:*0 � 0 ¼ 6*:*0%*:* (18)

The actual gypsum content after the introduction of corrective additives will

*The calculated composition of the raw mix for obtaining alite Portland cement clinker and its chemical*

**Clinker Raw mix composition Chemical composition of clinker, mass %**

**Сlay Gypsum**

*The calculated composition of the raw mix and the chemical composition of clinkers before and after the*

**Clinker Raw mix composition Chemical composition of clinker, mass %**

**The first stage clinker**

**Limestone**

*Cement Industry - Optimization, Characterization and Sustainable Application*

Clinkers before the gypsum

Clinkers after the gypsum

decomposition

decomposition

*gypsum decomposition.*

Portland cement clinker

**Table 4.**

**Table 5.**

*composition.*

Then the quantity of corrective additives is calculated. The quantity of corrective additives is equal to the difference between the quantity of raw components calculated using the formulas (11)–(14) and the quantity of raw components calcu-

A negative value for the clay amount means that it should be reduced. **Figure 3** shows the data of qualitative phase analysis of clinker prepared in accordance with correction calculation No. 1 and burnt at temperatures of 1150,

X-ray analysis indicates the absence of CaOfree in a clinker prepared in accordance with corrective calculations No. 1, at a burning temperature of 1200°C or higher. Stable alite in such clinker is formed already at the burning temperature of 1250°C as evidenced by the appearance of diffraction maxima with d = 1.76 Å and d = 3.04 Å which are typical for alite at this temperature. The change in the intensity of the diffraction maxima of the main phases of the clinker prepared in accordance with the correction calculation No. 1 and burnt at temperatures of 1150, 1200, 1250

decrease by:

1200, 1250 and 1300°C.

**92**

and 1300°C is shown in **Figure 4**.

lated at the first stage and shown in **Table 4**.

**Limestone**

The quantity of corrective additives is equal to:

*The data of qualitative phase analysis of clinker prepared in accordance with correction calculation No. 1 and burnt at temperatures of 1150, 1200, 1250 and 1300°C.*

#### **Figure 4.**

*The change in the intensity of the diffraction maxima of the main phases of the clinker prepared in accordance with the correction calculation No. 1 and burnt at temperatures of 1150, 1200, 1250 and 1300°C.*

Diffraction peak with d = 1.76 Å which is typical for C3S, increases up to a temperature of 1250°C and decreases starting from a temperature of 1250°C. The diffraction peak with d = 2.28 Å which is typical for C2S on the contrary decreases to a temperature of 1250°C and increases at temperatures above of 1250°C which indicates the transformation of alite part into belite according to Eq. (5). The intensity of the diffraction maximum with d = 3.72 Å which is typical for C3A3CS, decreases above the temperature of 1150°C, which indicates the decomposition of CaSO4 in accordance with the reaction (6) and decay as a result.

To determine the actual phase composition of the clinker prepared in accordance with the correction calculation No. 1 and synthesized at a temperature of 1300°C a quantitative x-ray phase analysis was performed and it is shown in **Figure 5**.

**Table 6** shows the phase composition of clinker synthesized in accordance with correction calculation No. 1 based on quantitative phase analysis.

On the basis of clinker prepared in accordance with corrective calculation No. 1 and synthesized at a temperature of 1300°C Portland cement was prepared by joint grinding of clinker with gypsum dihydrate (**Figure 6**). The cement activity was

determined on cubes with a size of 2x2x2 cm prepared from cement paste of normal density. The physical and mechanical properties of cement are shown in

Clinker No. 1 21.8 31.1 42.5 67.3

**%**

*\*S – Blaine's specific surface; R008 – residue on the sieve No. 008; ND – normal density.*

**Clinker type Compressive strength, MPa, after, days**

**S\*, m2/kg**

*Peculiarities of Portland Cement Clinker Synthesis in the Presence of a Significant Amount…*

Clinker No. 1 96 4 3.96 348 12.7 25.2 2–50 4–15

**R008, %**

**2 7 14 28**

**Clinker Gypsum Initial Final**

**ND, %**

**Setting time, hour-minute**

**5. Example of calculation of high-sulphate raw material mixture No. 2**

with the modular characteristics LSF = 1 and DS = 1. At DS = 1 calcium sulfoaluminate C3A3C S can be formed in the raw mix based on calcium

composition of clinkers before and after the gypsum decomposition.

clinker and its chemical composition is shown in **Table 10**.

**Limestone**

gypsum as one of the components of the raw mix and corrective additives:

of raw components of the clinker shown in **Table 9** by the quantity of clinker

At the first stage on the basis of raw components the chemical composition of which is shown in **Table 2** the raw mix of high-sulphate clinker is calculated for the synthesis of calcium monoaluminate in it according to the formulas (9) and (10)

monoaluminate and sulfospurrit 2(C2S)С S can be formed in the raw mix based on

**Table 9** shows the calculated composition of the raw mix and the chemical

At the second stage a alite Portland cement clinker with modular characteristics LSF = 0.92, n = 2.3, p = 1.7 is calculated on the basis of clinker after decomposition of

The calculated composition of the raw mix for obtaining alite Portland cement

Finally the composition of the raw mix is calculated by multiplying the quantity

**Clinker Raw mix composition Chemical composition of clinker, mass %**

*The calculated composition of the raw mix and the chemical composition of clinkers before and after the*

**Сlay Gypsum CaO SiO2 Al2O3 Fe2O3 SO3 Total**

59.8 21.3 18.9 60.3 16.5 6.6 3.9 12.7 100

59.8 21.3 18.0 69.1 18.9 7.5 4.5 0 100

**Tables 7** and **8**.

*Portland cement compressive strength.*

**Table 7.**

**Table 8.**

**Clinker type Composition, % SO3,**

*DOI: http://dx.doi.org/10.5772/intechopen.94915*

*The physical and mechanical properties of Portland cement.*

belite.

limestone and quartz sand.

Clinkers before the gypsum

Clinkers after the gypsum

decomposition

decomposition

*gypsum decomposition.*

**Table 9.**

**95**

#### **Figure 5.**

*The phase analysis data of clinker synthesized on the basis of raw mix in accordance with correction calculation No. 1.*


#### **Table 6.**

*The phase composition of clinker synthesized in accordance with correction calculation No. 1.*

#### **Figure 6.** *A micrograph of clinker synthesized in accordance with correction calculation No. 1.*

*Peculiarities of Portland Cement Clinker Synthesis in the Presence of a Significant Amount… DOI: http://dx.doi.org/10.5772/intechopen.94915*


**Table 7.**

To determine the actual phase composition of the clinker prepared in accordance with the correction calculation No. 1 and synthesized at a temperature of 1300°C a quantitative x-ray phase analysis was performed and it is shown in **Figure 5**.

**Table 6** shows the phase composition of clinker synthesized in accordance with

On the basis of clinker prepared in accordance with corrective calculation No. 1 and synthesized at a temperature of 1300°C Portland cement was prepared by joint grinding of clinker with gypsum dihydrate (**Figure 6**). The cement activity was

*The phase analysis data of clinker synthesized on the basis of raw mix in accordance with correction*

Three calcium silicate (alite) C3S 77.8 Two calcium silicate (belit) C2S 6.9 Brownmillerit C4AF 15.3

*The phase composition of clinker synthesized in accordance with correction calculation No. 1.*

*A micrograph of clinker synthesized in accordance with correction calculation No. 1.*

**Name of mineral phase Guantity in clinker, mas. %**

correction calculation No. 1 based on quantitative phase analysis.

*Cement Industry - Optimization, Characterization and Sustainable Application*

**Figure 5.**

**Table 6.**

**Figure 6.**

**94**

*calculation No. 1.*

*The physical and mechanical properties of Portland cement.*


#### **Table 8.**

*Portland cement compressive strength.*

determined on cubes with a size of 2x2x2 cm prepared from cement paste of normal density. The physical and mechanical properties of cement are shown in **Tables 7** and **8**.

## **5. Example of calculation of high-sulphate raw material mixture No. 2**

At the first stage on the basis of raw components the chemical composition of which is shown in **Table 2** the raw mix of high-sulphate clinker is calculated for the synthesis of calcium monoaluminate in it according to the formulas (9) and (10) with the modular characteristics LSF = 1 and DS = 1. At DS = 1 calcium sulfoaluminate C3A3C S can be formed in the raw mix based on calcium monoaluminate and sulfospurrit 2(C2S)С S can be formed in the raw mix based on belite.

**Table 9** shows the calculated composition of the raw mix and the chemical composition of clinkers before and after the gypsum decomposition.

At the second stage a alite Portland cement clinker with modular characteristics LSF = 0.92, n = 2.3, p = 1.7 is calculated on the basis of clinker after decomposition of gypsum as one of the components of the raw mix and corrective additives: limestone and quartz sand.

The calculated composition of the raw mix for obtaining alite Portland cement clinker and its chemical composition is shown in **Table 10**.

Finally the composition of the raw mix is calculated by multiplying the quantity of raw components of the clinker shown in **Table 9** by the quantity of clinker


**Table 9.**

*The calculated composition of the raw mix and the chemical composition of clinkers before and after the gypsum decomposition.*


#### **Table 10.**

*The calculated composition of the raw mix for obtaining alite Portland cement clinker and its chemical composition.*

shown in **Table 10**, and is summed up with the quantity of raw components shown in **Table 10**:

$$\text{CaCO}\_3 = (\text{59}, \text{8x0}, \text{729}) + 20, \text{8} = \text{64}, \text{396};\tag{19}$$

$$\text{Clay} = \text{21, 3x0, 729} = \text{15, 596};\tag{20}$$

$$\text{SiO}\_2 = \text{€}, 4\text{\%};\tag{21}$$

To determine the actual phase composition of the clinker prepared in accordance with the correction calculation No. 2 and synthesized at a temperature of 1350°C a quantitative x-ray phase analysis was performed. Its results shown in **Figure 8**. **Table 11** summarizes the results of quantitative x-ray phase analysis of

*The data of qualitative phase analysis of clinker prepared in accordance with calculation No. 2 and burnt at*

*Peculiarities of Portland Cement Clinker Synthesis in the Presence of a Significant Amount…*

The test results show that in accordance with corrective calculation No. 2 a significant amount of C3S is retained when preparing clinker based on a high-

On the basis of clinker prepared at temperature of 1350°С Portland cement was prepared by joint grinding of clinker with natural gypsum. The cement activity was determined on cubes with a size of 2x2x2 cm prepared from cement paste of normal

The physical and mechanical properties of cement are shown in **Tables 12** and **13**.

*The phase analysis data of clinker synthesized on the basis of raw mix in accordance with correction calculation*

Examples data of corrective calculations show that using the proposed calculation method it is possible to save a significant amount of C3S in a clinker

sulphate raw mix that initially contains 12.7% SO3 (**Figure 9**).

synthesized on the basis of a high-sulphate raw mix.

synthesized clinker.

*temperatures of 1100, 1200, 1300 and 1350°C.*

*DOI: http://dx.doi.org/10.5772/intechopen.94915*

density.

**Figure 8.**

*No. 2.*

**97**

**Figure 7.**

$$\text{Gypsum} = (\mathbf{18}, \mathbf{9x0}, \mathbf{729}) = \mathbf{13}, \mathbf{89}.\tag{22}$$

Then the quantity of corrective additives is calculated. The quantity of corrective additives is equal to the difference between the quantity of raw components calculated using the formulas (19) and (20) and the quantity of raw components calculated at the first stage and shown in **Table 9**.

The quantity of corrective additives is equal to:

$$\text{CaCO}\_3 = 64, 3-59, 8, \,= 4, 496; \tag{23}$$

$$\text{Clay} = \mathbf{15}, \mathbf{5} - \mathbf{21}, \mathbf{3} = -\mathbf{5}, \mathbf{896};\tag{24}$$

$$\text{SiO}\_2 = \text{€}, 4-\text{O} = \text{€}, 4\text{@};\tag{25}$$

A negative value for the clay amount means that it should be reduced the same as in the calculation example No. 1.

The actual gypsum content after the introduction of corrective additives will decrease by:

$$\text{CaSO}\_4 = \text{18,9} - \text{13,8} = \text{5,1} \tag{26}$$

**Figure 7** shows the data of qualitative x-ray phase analysis of clinker prepared in accordance with calculation mentioned above and burnt at temperatures of 1100, 1200, 1300 and 1350°C.

X-ray analysis indicates the absence of CaOfree in a clinker prepared in accordance with corrective calculations No. 2 at a burning temperature above 1300°C. Stable alite C3S is formed at the burning temperature of 1350°C as evidenced by the appearance of diffraction maxima with d = 1.76 Å and d = 3.04 Å which are typical for alite at this temperature.

The intensity of the diffraction maximum with d = 3.72 Å which is typical for C3A3C S increases to a temperature of 1300°C but above this temperature it is not fixed which indicates the decomposition of CaSO4 in accordance with the reaction (No. 6) and decay as a result.

According to the qualitative phase analysis data a significant amount of gypsum is released up to the burning temperature of 1300°C which is fixed by the diffraction maximum with d = 3.47 Å. Gypsum remains are fixed even at a temperature of 1350°C.

*Peculiarities of Portland Cement Clinker Synthesis in the Presence of a Significant Amount… DOI: http://dx.doi.org/10.5772/intechopen.94915*

**Figure 7.**

shown in **Table 10**, and is summed up with the quantity of raw components shown

*The calculated composition of the raw mix for obtaining alite Portland cement clinker and its chemical*

**Clinker Raw mix composition Chemical composition of clinker, mass %**

**The first stage clinker**

*Cement Industry - Optimization, Characterization and Sustainable Application*

Then the quantity of corrective additives is calculated. The quantity of corrective additives is equal to the difference between the quantity of raw components calculated using the formulas (19) and (20) and the quantity of raw components

A negative value for the clay amount means that it should be reduced the same

**Figure 7** shows the data of qualitative x-ray phase analysis of clinker prepared in accordance with calculation mentioned above and burnt at temperatures of 1100,

X-ray analysis indicates the absence of CaOfree in a clinker prepared in accordance with corrective calculations No. 2 at a burning temperature above 1300°C. Stable alite C3S is formed at the burning temperature of 1350°C as evidenced by the appearance of diffraction maxima with d = 1.76 Å and d = 3.04 Å which are typical

The intensity of the diffraction maximum with d = 3.72 Å which is typical for C3A3C S increases to a temperature of 1300°C but above this temperature it is not fixed which indicates the decomposition of CaSO4 in accordance with the reaction

According to the qualitative phase analysis data a significant amount of gypsum is released up to the burning temperature of 1300°C which is fixed by the

diffraction maximum with d = 3.47 Å. Gypsum remains are fixed even at a

The actual gypsum content after the introduction of corrective additives will

calculated at the first stage and shown in **Table 9**. The quantity of corrective additives is equal to:

**Limestone**

as in the calculation example No. 1.

CaCO3 ¼ ð Þþ 59, 8х0, 729 20, 8 ¼ 64, 3%; (19)

20.8 72.9 6.4 68.3 22.1 6.0 3.6 0 100

Clay ¼ 21, 3х0, 729 ¼ 15, 5%; (20)

Gypsum ¼ ð Þ¼ 18, 9х0, 729 13, 8%*:* (22)

CaCO3 ¼ 64, 3 � 59, 8, ¼ 4, 4%; (23) Clay ¼ 15, 5 � 21, 3 ¼ �5, 8%; (24) SiO2 ¼ 6, 4 � 0 ¼ 6, 4%; (25)

CaSO4 ¼ 18, 9 � 13, 8 ¼ 5, 1*:* (26)

SiO2 ¼ 6, 4%; (21)

**SiO2 CaO SiO2 Al2O3 Fe2O3 SO3**

P

in **Table 10**:

**Table 10.**

*composition.*

Portland cement clinker

decrease by:

1200, 1300 and 1350°C.

for alite at this temperature.

(No. 6) and decay as a result.

temperature of 1350°C.

**96**

*The data of qualitative phase analysis of clinker prepared in accordance with calculation No. 2 and burnt at temperatures of 1100, 1200, 1300 and 1350°C.*

To determine the actual phase composition of the clinker prepared in accordance with the correction calculation No. 2 and synthesized at a temperature of 1350°C a quantitative x-ray phase analysis was performed. Its results shown in **Figure 8**.

**Table 11** summarizes the results of quantitative x-ray phase analysis of synthesized clinker.

The test results show that in accordance with corrective calculation No. 2 a significant amount of C3S is retained when preparing clinker based on a highsulphate raw mix that initially contains 12.7% SO3 (**Figure 9**).

On the basis of clinker prepared at temperature of 1350°С Portland cement was prepared by joint grinding of clinker with natural gypsum. The cement activity was determined on cubes with a size of 2x2x2 cm prepared from cement paste of normal density.

The physical and mechanical properties of cement are shown in **Tables 12** and **13**.

Examples data of corrective calculations show that using the proposed calculation method it is possible to save a significant amount of C3S in a clinker synthesized on the basis of a high-sulphate raw mix.

**Figure 8.**

*The phase analysis data of clinker synthesized on the basis of raw mix in accordance with correction calculation No. 2.*

## *Cement Industry - Optimization, Characterization and Sustainable Application*


**Table 11.**

*The phase composition of clinker synthesized in accordance with correction calculation No. 2.*

#### **Figure 9.**

*A micrograph of clinker synthesized in accordance with correction calculation No. 2.*


The quantity of clay removed from the raw mix correlates with the amount of mix additives put in the raw mix, i.e. with the same modular characteristics of the clinker the minimum quantity of clay removed corresponds to a minimum quantity

**Clinker type The value of the endo effect, J/g Mass loss, %** Clinker 0 148.2 17.9 Clinker 1 167.0 19.2 Clinker 2 180.5 17.5 CEM I 42.5 155.0 18.3

*Peculiarities of Portland Cement Clinker Synthesis in the Presence of a Significant Amount…*

The **Table 14** shows the values of the first endo-effect and the total mass loss of

The present study revealed that the SO3 negative impact on the Portland cement clinker synthesis, resulted in a C3S content reduction and the C2S and С3А content increasing in the final product. It leads to lowering clinker fire resistance and cement quality due to the thermodynamic preference of the ye'elimite C4A3

synthesis in the presence SO3 and, consequently, the presence of low-basic calcium

A method for elimination of the SO3 negative impact on the Portland cement quality by calculating the raw material mixture composition with a significant

monoaluminate CA in the synthesized clinker. In the presence of calcium monoaluminate, solid-phase synthesis of high-base C3A and C4AF is thermodynamically impossible. As a result, free lime accumulates in the synthesized clinker,

S

At hydration alite attaches 5 molecules of water, but belite only 2. Due to this

of additives and the maximum quantity of clay removed corresponds to the

At the final stage of investigation сomparative thermal analysis (TA) of hydration products was conducted. Results of tests are resulted on **Figure 10**.

maximum quantity of additives.

difference, the clinker 0 has smallest first endo effect.

*Results of сomparative thermal analysis (TA) of hydration products.*

*DOI: http://dx.doi.org/10.5772/intechopen.94915*

*Values of the first endo-effect and the total mass loss of samples.*

which prevents the liquid-phase synthesis of C3S.

amount of SO3 has been developed and patented.

samples.

**99**

**Figure 10.**

**Table 14.**

**6. Сonclusion**

#### **Table 12.**

*The physical and mechanical properties of Portland cement.*


#### **Table 13.**

*Portland cement compressive strength.*

The quantity of corrective additives depends on the modular characteristics of the synthesized clinker. When limiting the modular characteristics of Portland cement clinker LSF = 0.92–0.98; n = 2.0–3.0; p = 1.7–4.0 the minimum amount of additives equal to 4.0% is introduced with the minimum values of modular characteristics, i.e. LSF = 0.92; n = 2.0; p = 1.7; and with the minimum amount of gypsum introduced, i.e. DS =0. The maximum amount of corrective additives equal to 23.0% is introduced with the maximum values of modular characteristics, i.e. LSF = 0.98; n = 3.0; p = 4.0 and with the maximum amount of gypsum introduced, i.e. DS =1.

*Peculiarities of Portland Cement Clinker Synthesis in the Presence of a Significant Amount… DOI: http://dx.doi.org/10.5772/intechopen.94915*

**Figure 10.**

*Results of сomparative thermal analysis (TA) of hydration products.*


#### **Table 14.**

*Values of the first endo-effect and the total mass loss of samples.*

The quantity of clay removed from the raw mix correlates with the amount of mix additives put in the raw mix, i.e. with the same modular characteristics of the clinker the minimum quantity of clay removed corresponds to a minimum quantity of additives and the maximum quantity of clay removed corresponds to the maximum quantity of additives.

At the final stage of investigation сomparative thermal analysis (TA) of hydration products was conducted. Results of tests are resulted on **Figure 10**.

The **Table 14** shows the values of the first endo-effect and the total mass loss of samples.

At hydration alite attaches 5 molecules of water, but belite only 2. Due to this difference, the clinker 0 has smallest first endo effect.

## **6. Сonclusion**

The present study revealed that the SO3 negative impact on the Portland cement clinker synthesis, resulted in a C3S content reduction and the C2S and С3А content increasing in the final product. It leads to lowering clinker fire resistance and cement quality due to the thermodynamic preference of the ye'elimite C4A3 S synthesis in the presence SO3 and, consequently, the presence of low-basic calcium monoaluminate CA in the synthesized clinker. In the presence of calcium monoaluminate, solid-phase synthesis of high-base C3A and C4AF is thermodynamically impossible. As a result, free lime accumulates in the synthesized clinker, which prevents the liquid-phase synthesis of C3S.

A method for elimination of the SO3 negative impact on the Portland cement quality by calculating the raw material mixture composition with a significant amount of SO3 has been developed and patented.

The quantity of corrective additives depends on the modular characteristics of the synthesized clinker. When limiting the modular characteristics of Portland cement clinker LSF = 0.92–0.98; n = 2.0–3.0; p = 1.7–4.0 the minimum amount of additives equal to 4.0% is introduced with the minimum values of modular characteristics, i.e. LSF = 0.92; n = 2.0; p = 1.7; and with the minimum amount of gypsum introduced, i.e. DS =0. The maximum amount of corrective additives equal to 23.0% is introduced with the maximum values of modular characteristics, i.e. LSF = 0.98; n = 3.0; p = 4.0 and with the maximum amount of gypsum

Clinker No. 2 10.1 14.7 20.0 44.7

**Name of mineral phase Guantity in clinker, mas. %**

Three calcium silicate (alite) C3S 65.9 Two calcium silicate (belit) C2S 22.5 Brownmillerit C4AF 11.7

*Cement Industry - Optimization, Characterization and Sustainable Application*

*The phase composition of clinker synthesized in accordance with correction calculation No. 2.*

*A micrograph of clinker synthesized in accordance with correction calculation No. 2.*

*\*S – Blaine's specific surface; R008 – residue on the sieve No. 008; ND – normal density.*

**Clinker type Compressive strength, MPa, after, days**

*The physical and mechanical properties of Portland cement.*

**Clinker type Composition, % SO3, % S\*, m2/kg R008, % ND, % Setting time,**

Clinker No. 2 100 0 12.7 378 3.1 28.3 1–50 2–15

**Clinker Gypsum Initial Final**

**2 7 14 28**

**hour-minute**

introduced, i.e. DS =1.

*Portland cement compressive strength.*

**Table 11.**

**Figure 9.**

**Table 12.**

**Table 13.**

**98**

**References**

p.1–14.

[1] Factors el Mar Cortada Mut, Linda Kaare Norskov, Peter Glarborg, Kim Dam-Johansen Sulphur release from alternative fuel firing / Maria del Mar Cortada Mut & other//Global Cement

*DOI: http://dx.doi.org/10.5772/intechopen.94915*

and Building Materials 137 (2017)

[9] Sayed Horkoss, Roger Lteif, and Toufic Rizk Calculation of the C3A Percentage in High Sulfur Clinker / Horcoss Sayed & other // International Journal of Analytical Chemistry

Volume 2010, Article ID 102146, p. 1–5.

[11] Donald H. Campbell. Microscopical Examination and Interpretation of Portland Cement and Clinker Second Edition/ Published by:Portland Cement

Association – USA, 1999. 214 p.

Mchedlov-Petrosjan, O.M.

Stroyizdat, 1986.408 p.

– p. 131–142

[12] Babushkin, V.I., Matveev G.M.,

Thermodynamics Of Silicates - М:

[13] Kuznezova T.V. Aluminate and sulfoaluminate cements/ - М.: Stroyizdat, 1986., 208 p.

[14] Michael A. Miheenkov Compacting as a way of reception sulfated hydraulic binders/Vestnik MGSU.- – 2011. – № 1 .

[15] Patent 2527430 Russian Federation: MPK C04B 7/36. Method for Correcting Composition of Portland Cement Clincer Based on Highe-Sulphate Crude

Miheenkov., Patent Holder: Michael A. Miheenkov. – 2013112990/03; Date of declare. 22.03.2013 ; Date of publication.

Mixture. Author: Michael A.

27.08.2014. Bulletin. № 24.

[10] Laure Pelletier-Chaignat, Frank Winnefeld, Barbara Lothenbach, Gwenn Le Saout Influence of the calcium sulphate source on the hydration mechanism of Portland cement–calcium sulphoaluminate clinker–calcium sulphate binders/ Pelletier-Chaignat Laure & other // Cement & Concrete Composites 33

p. 300–306.

*Peculiarities of Portland Cement Clinker Synthesis in the Presence of a Significant Amount…*

(2011) p. 551–561.

Magazine 9 (2014) p. 36–41.

[2] Július Strigáč Effect of Selected Alternative Fuels and Raw Materials on the Cement Clinker Quality/ Strigáč Július // Journal Of Civil Engineering Vol. 10, Issue 2, 2015 p. 81–92.

[3] Ying-Liang Chen, Juu-En Chang , Ming-Sheng Ko Reusing Desulfurization Slag in Cement Clinker Production and the Influence on the Formation of Clinker Phases/ Chen Ying-Liang & other// Sustainability 9, 1585 (2017)

[4] Javed I. Bhatty.; Role of Minor Elements in Cement Manufacture and Use, Portland Cement Association, Skokie, Illinois 1995, p.24–25.

[5] M. Yamashita, H. Tanaka Low Temperature Burnt Portland Cement

Yamashita M., Tanaka H. // Cement Science and Concrete Technology № 65

[6] H.F.W. Taylor, Cement Chemistry, Academic Press, London, 1990.

[7] Sayed Horcoss Influence of the

characteristics / Horcoss Sayed, Ltief Roger, RizkToufic//Cement And Concrete Research 41 (2011). p. 913– 919. Available from: http://www.scie ncedirect.com/science/article/pii/

[8] Mieke De Schepper, Philip Van den Heede, Eleni C. Arvaniti, Klaartje De Buysser Sulfates in Completely Recyclable Concrete and the effect of CaSO4 on the clinker mineralogy/ Schepper De & other //Construction

clinker SO3 on the cement

S0008884611001268

**101**

Clinker Using Mineralizer/

(2011) p. 82–87.

## **Abbreviations**


## **Author details**

Oleg Sheshukov\* and Michael Mikheenkov Ural Federal University Named after the First President of Russia B.N. Yeltsin, Institute of Metallurgy of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russian Federation

\*Address all correspondence to: o.j.sheshukov@urfu.ru

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Peculiarities of Portland Cement Clinker Synthesis in the Presence of a Significant Amount… DOI: http://dx.doi.org/10.5772/intechopen.94915*

## **References**

**Abbreviations**

C3A3C

2(C2S)С

**Author details**

**100**

Oleg Sheshukov\* and Michael Mikheenkov

provided the original work is properly cited.

\*Address all correspondence to: o.j.sheshukov@urfu.ru

Ekaterinburg, Russian Federation

Ural Federal University Named after the First President of Russia B.N. Yeltsin, Institute of Metallurgy of the Ural Branch of the Russian Academy of Sciences,

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

C3S 3CaOSiO2; C2S 2CaOSiO2; C3A 3CaOAl2O3; C4AF 4CaOAl2O3Fe2O3;

C12A7 12CaO7Al2O3; CaOfree free CaO;

LOI Loss On Ignition.

The following abbreviations are used in this manuscript:

*Cement Industry - Optimization, Characterization and Sustainable Application*

S 3CaO3Al2O3CaSO4;

SC Saturation Coefficient; LSF Lime Saturation Factor;

S 2(2CaOSiO2)CaSO4;

DS Degree of Saturation by Sulfate;

[1] Factors el Mar Cortada Mut, Linda Kaare Norskov, Peter Glarborg, Kim Dam-Johansen Sulphur release from alternative fuel firing / Maria del Mar Cortada Mut & other//Global Cement Magazine 9 (2014) p. 36–41.

[2] Július Strigáč Effect of Selected Alternative Fuels and Raw Materials on the Cement Clinker Quality/ Strigáč Július // Journal Of Civil Engineering Vol. 10, Issue 2, 2015 p. 81–92.

[3] Ying-Liang Chen, Juu-En Chang , Ming-Sheng Ko Reusing Desulfurization Slag in Cement Clinker Production and the Influence on the Formation of Clinker Phases/ Chen Ying-Liang & other// Sustainability 9, 1585 (2017) p.1–14.

[4] Javed I. Bhatty.; Role of Minor Elements in Cement Manufacture and Use, Portland Cement Association, Skokie, Illinois 1995, p.24–25.

[5] M. Yamashita, H. Tanaka Low Temperature Burnt Portland Cement Clinker Using Mineralizer/ Yamashita M., Tanaka H. // Cement Science and Concrete Technology № 65 (2011) p. 82–87.

[6] H.F.W. Taylor, Cement Chemistry, Academic Press, London, 1990.

[7] Sayed Horcoss Influence of the clinker SO3 on the cement characteristics / Horcoss Sayed, Ltief Roger, RizkToufic//Cement And Concrete Research 41 (2011). p. 913– 919. Available from: http://www.scie ncedirect.com/science/article/pii/ S0008884611001268

[8] Mieke De Schepper, Philip Van den Heede, Eleni C. Arvaniti, Klaartje De Buysser Sulfates in Completely Recyclable Concrete and the effect of CaSO4 on the clinker mineralogy/ Schepper De & other //Construction

and Building Materials 137 (2017) p. 300–306.

[9] Sayed Horkoss, Roger Lteif, and Toufic Rizk Calculation of the C3A Percentage in High Sulfur Clinker / Horcoss Sayed & other // International Journal of Analytical Chemistry Volume 2010, Article ID 102146, p. 1–5.

[10] Laure Pelletier-Chaignat, Frank Winnefeld, Barbara Lothenbach, Gwenn Le Saout Influence of the calcium sulphate source on the hydration mechanism of Portland cement–calcium sulphoaluminate clinker–calcium sulphate binders/ Pelletier-Chaignat Laure & other // Cement & Concrete Composites 33 (2011) p. 551–561.

[11] Donald H. Campbell. Microscopical Examination and Interpretation of Portland Cement and Clinker Second Edition/ Published by:Portland Cement Association – USA, 1999. 214 p.

[12] Babushkin, V.I., Matveev G.M., Mchedlov-Petrosjan, O.M. Thermodynamics Of Silicates - М: Stroyizdat, 1986.408 p.

[13] Kuznezova T.V. Aluminate and sulfoaluminate cements/ - М.: Stroyizdat, 1986., 208 p.

[14] Michael A. Miheenkov Compacting as a way of reception sulfated hydraulic binders/Vestnik MGSU.- – 2011. – № 1 . – p. 131–142

[15] Patent 2527430 Russian Federation: MPK C04B 7/36. Method for Correcting Composition of Portland Cement Clincer Based on Highe-Sulphate Crude Mixture. Author: Michael A. Miheenkov., Patent Holder: Michael A. Miheenkov. – 2013112990/03; Date of declare. 22.03.2013 ; Date of publication. 27.08.2014. Bulletin. № 24.

Section 3

Comparative Parameters

of Cement Production

**103**

[16] Kind V.A. Chemical characteristics of Portland cement/ L.-М. Gosstroyizdat, 1932..

[17] Walter H. Duda Cement.; Data-Book /Internationale Verfahrenstechniken der Zementindustrie 2., Auflage Bauverlag GmbH Wfmbaden and Berlin, 1981, 484 p.

[18] Atakuziev, T.A. Sulfomineral cements on a basis of phosphogypsum/ T.A.Atakuziev, F.M.Mirzoev.: "FAN", 1979. – 152 p.

Section 3
