CN104058617B - A kind of Portland clinker and preparation method thereof - Google Patents

Abstract

The invention discloses a Portland cement clinker, which contains trace amounts of magnesium and phosphorus, and R-type alite with a weight percentage of 52% to 64%. Also disclosed is a preparation method of Portland cement clinker, comprising the following steps: step 1, selecting raw meal components according to the composition of the required cement clinker and determining the weight ratio of each raw meal component, the raw meal composition Include at least one magnesium-containing raw material, including at least one phosphorus-containing raw material; step 2, fully mix the above-mentioned raw material components, then calcinate at high temperature, and quickly cool to room temperature to prepare cement clinker; In the material, the phosphorus content is calculated as the oxide _P2O5 , and the mass percentage is _0.5 % to 1.2%; the magnesium content is calculated as the oxide MgO, and the mass percentage is 1% to 5%. The tricalcium silicate in the cement clinker prepared by the method of the present invention is R-type, and the compressive strength of the clinker can be greatly improved compared with the clinker without implementing the technology.

Description

A kind of Portland cement clinker and preparation method thereof

technical field

The invention relates to the technical field of building materials, in particular to a Portland cement clinker and a preparation method of the Portland cement clinker.

Background technique

Portland cement has been used since its invention and is the most widely used inorganic cementitious material. my country's cement output has ranked first in the world for more than 20 consecutive years. In 2013, it reached 2.41 billion tons, accounting for about 60% of the world's total cement output, of which Portland cement accounted for more than 98%. The huge quantity meets the needs of national construction, but the overall quality is still far from the world's advanced level: low intensity and high energy consumption restrict the sustainable development of the industry.

Portland cement is prepared by mixing Portland cement clinker with a small amount of gypsum and admixtures. Good quality cement mainly depends on clinker. The mineral composition characteristics of Portland cement clinker are mainly Alite minerals (solid solution of tricalcium silicate 3CaO·SiO ₂ =C ₃ S), and other minerals are Belite minerals (dicalcium silicate 2CaO·SiO ₂ = solid solution of C ₂ S), tricalcium aluminate (3CaO·Al ₂ O ₃ =C ₃ A), tetracalcium aluminoferrite (4CaO·Al ₂ O ₃ ·Fe ₂ O ₃ =C ₄ AF) and other minerals . Alite has the best comprehensive physical and chemical properties and the highest content among several minerals, which determines a series of basic properties such as the setting and strength of cement. Therefore, the key to improving the quality of Portland cement is to increase the content of alite or increase the activity of alite. However, raising the content of alite inevitably caused problems such as difficulty in clinker firing. Alite has 7 crystal forms in 3 crystal systems, namely triclinic (T includes T1, T2, T3), monoclinic (M includes M1, M2, M3), and tripartite (R), which can be produced in different temperature ranges. Transform each other. The symmetry of these seven crystal forms increases successively from T1 to R, and the activity also increases successively. Therefore, it is the most fundamental problem to improve the quality of clinker to obtain R-type C ₃ S with high activity and high metastable stability. Changing the clinker sintering process can also adjust the C ₃ S crystal form through heat treatment, etc., but the preparation process requires natural cooling or heat preservation during cooling, which not only conforms to the existing clinker production process, but also causes great energy waste . It can be seen that without changing the existing sintering process and without increasing the energy consumption of clinker sintering, stabilizing the highly active alite crystal form by doping ions, and exerting the role of doping ions to optimize the strength of alite is to improve the clinker. The fundamental way of strength. Different crystal forms of C ₃ S can be prepared by ion doping. It has been reported in the literature that the introduction of high doped Zn, Cu or Ti into pure C ₃ S can stabilize the R-type. However, these technical solutions are not only limited by the source of raw materials, but the heavy metal Zn introduced And Cu will also cause certain damage or safety hazards in the process of preparation or application. In particular, clinker is a Ca-Si-Al-Fe multi-component system with a complex composition and structure, which makes it difficult to break through the controllability of the crystal form. The efficient, reliable and stable R-type C ₃ S suitable for clinker to improve clinker strength has not yet been obtained. method.

Contents of the invention

The purpose of this invention is to propose a preparation method of Portland cement clinker, so that Alite in the prepared Portland cement clinker is a highly active R-type, and the strength of the clinker is improved to solve the need to change the existing technology. The clinker sintering process may need to be mixed with heavy metals such as Zn, Cu or F to cause environmental pollution.

In order to solve the problems of the technologies described above, the present invention adopts the following technical solutions:

A preparation method of Portland cement clinker, comprising the following steps:

Step 1, selecting raw meal components according to the composition of the required cement clinker and determining the weight ratio of each raw meal component, the raw meal components include at least one magnesium-containing raw material, and include at least one phosphorus-containing raw material;

Step 2, fully mixing the above raw meal components, then calcining at high temperature, and rapidly cooling to room temperature to prepare cement clinker;

In the cement clinker, the phosphorus content is calculated as the oxide P ₂ O ₅ , and the mass percentage is 0.5% to 1.2%; the magnesium content is calculated as the oxide MgO, and the mass percentage is 1% to 5%.

According to the preparation method of Portland cement clinker described above, further, the temperature range of high-temperature calcination is 1400°C to 1500°C.

According to the preparation method of Portland cement clinker as described above, further, the obtained cement clinker is ground, and the fineness of the sample is controlled to grind to a specific surface area of 320-360 m ² /kg.

There is Portland cement clinker prepared by the above method, which contains trace amounts of magnesium and phosphorus, and 52%-64% by weight of R-type alite.

Portland cement clinker as described above, comprising the following components, by weight percentage,

R-type Alite C ₃ S: 52% to 64%;

Belite C ₂ S: 14% to 26%;

Tricalcium aluminate C ₃ A: 6% to 11%;

Tetracalcium aluminoferrite C ₄ AF: 9-15%;

Free calcium oxide f-CaO: 0~1.5%;

The balance is other phases, wherein the trace amount of magnesium is 1%-5% as MgO; the trace amount of phosphorus is 0.5%-1.2% as P ₂ O ₅ .

For the Portland cement clinker mentioned above, further, the weight percentage of R-type Alite is 54%-60%.

Compared with prior art, the beneficial effect of the present invention is:

1. The preparation method of the present invention achieves the purpose of stabilizing R-type C ₃ S and improving the strength of the clinker by ensuring the content of magnesium and phosphorus in the clinker, without adding additional components that pollute the environment such as fluorine and sulfur, which is environmentally friendly, safe and reliable, and The raw materials used have a wide range of sources and strong applicability.

2. The preparation method of the present invention does not change the existing production process, does not increase the energy consumption of clinker firing, and greatly improves the clinker strength.

3. The clinker prepared by the present invention has high strength. When preparing cement of the same strength grade, the amount of clinker can be reduced, the amount of mixed materials can be increased, the application efficiency of clinker can be improved, energy saving can be achieved, waste can be reduced.

4. The tricalcium silicate in the cement clinker prepared by the method of the present invention is R-type, and the compressive strength of the clinker can be greatly improved compared with the clinker that has not implemented the technology.

Description of drawings

Figure 1a is a schematic diagram of the Alite local characteristic fingerprint area of sample A in Example 1 of the present invention;

Figure 1b is a schematic diagram of the Alite local characteristic fingerprint area of sample B in Example 1 of the present invention;

Figure 1c is a schematic diagram of the Alite local characteristic fingerprint area of sample C in Example 1 of the present invention;

Figure 1d is a schematic diagram of the Alite local characteristic fingerprint area of sample D in Example 1 of the present invention;

Fig. 2 is a schematic diagram of the Alite local characteristic fingerprint area of samples C0 and C1 in Example 2 of the present invention;

3 is a schematic diagram of the Alite local characteristic fingerprint area of sample E in Example 4 of the present invention;

4 is a schematic diagram of the Alite local characteristic fingerprint area of sample F in Example 4 of the present invention;

5 is a schematic diagram of the Alite local characteristic fingerprint area of sample G in Example 4 of the present invention;

Fig. 6 is a schematic diagram of the Alite local characteristic fingerprint area of sample H in Example 4 of the present invention.

detailed description

The present invention will be described in further detail below in conjunction with specific examples, but not as a limitation of the present invention.

The present invention is aimed at Alite, the main provider of cement clinker strength, by introducing control components into the complex multi-system clinker, so that Alite retains the highly active R crystal form, and prepares R-type Alite portland cement Clinker, to achieve the purpose of improving the strength of cement clinker. In a clinker system with a typical composition, Alite inevitably has Na ⁺ , K ⁺ , Mg ²⁺ , Al ³⁺ , Fe ³⁺ and other ions in solid solution at the same time, and the clinker often does not contain phosphorus or contains There is a very small amount of phosphorus (usually 0-0.3wt% calculated as phosphorus oxide), and Alite is mainly in the monoclinic M3 crystal form. The invention can prepare the cement clinker containing high activity R type alite by adjusting the Mg content in the clinker and introducing a certain content of phosphorus into the clinker.

Example 1:

The mineral composition of the designed clinker is C ₃ S: 61%, C ₂ S: 20%, C ₃ A: 7% and C ₄ AF: 12%, and the raw meal rate values are KH=0.898, n=2.5, p= 1.31, the content of MgO in the clinker is 2%, the phosphorus-containing raw material mainly in the form of minerals containing CaHPO ₄ 2H ₂ O is the phosphorus source (the following examples are the same), and the amount of phosphorus introduced in the clinker is 1% P ₂ O ₅ . As a comparison A does not contain magnesium and phosphorus in the clinker; as a comparison B contains magnesium but does not contain phosphorus in the clinker; as a comparison C does not contain magnesium but contains phosphorus in the clinker. The chemical composition of the obtained cement clinker is shown in Table 1. According to the calculated ratio of raw materials, the raw materials are mixed and mixed evenly. The mixed raw materials are calcined in a high-temperature furnace at 1450°C and then quenched. The cooled clinker is crushed and ground, and the specific surface area of the clinker fineness is controlled to (340±20) m ² /kg by using Blaine specific surface area measuring instrument.

Table 1 Chemical composition of clinker

Figure 1 shows the diffraction peaks in the ranges of 32°-33° and 51°-52° of Alite's local characteristic fingerprints in the prepared clinker samples (Cu K _α2 diffraction has been deducted). Sample A does not contain Mg and P, due to the solid solution of other impurities The crystal plane spacing is close to that of ₍₂₂₄₎ , resulting in the merger of the diffraction peaks of the two crystal planes. There are two shoulder peaks around the ₍₆₂₀₎ diffraction peak between 51° and 52°, corresponding to the monoclinic M1 crystal form and the monoclinic M3 crystal form, respectively. The ₍₀₄₀₎ diffraction peak of type A indicates that alitide in sample A is a mixed crystal form of M1 and M3. Sample B contains 2% MgO and does not contain P. There are 3 small branched peaks between 32°-33°, and 2 small branched peaks at 51°-52°, showing a typical M3 crystal form. The presence of MgO can promote firing and affect the solid solution reaction, sample C contains ₁ % _P2O5 but does not contain Mg, resulting in a relatively large amount of _C2S in the clinker, Alite’s Although the crystal plane diffraction of (224) and ₍₂₂₄₎ merges, there are still two crystal plane diffraction peaks ₍₆₂₀₎ and ₍₀₄₀₎ between 51-52°, indicating that it is the M3 crystal form. Example 1 (sample D) contains 2% MgO and 1% P ₂ O ₅ at the same time, there are only two diffraction peaks at 32°-33°, and there is only one R-type ₍₂₂₀₎ between 51-52° Diffraction peaks of the crystal plane indicate that Alite in D clinker is R type.

The clinker prepared above was mixed with 5% gypsum, and the compressive strength test was carried out on the clinker sample according to GB/T17671-1999. The water-cement ratio is 0.5, mixed with water to make a 40mm×40mm×40mm mortar test block, cured according to the standard, and its compressive strength was measured for 3 days, 7 days, 28 days and 90 days, see Table 2.

Table 2 Free calcium content, specific surface area and strength properties of clinker samples

Example 2:

According to the current chemical composition and mineral composition of China's benchmark clinker for cement (hereinafter referred to as benchmark clinker), the mineral composition of the designed clinker is C ₃ S: 60%, C ₂ S: 23%, C ₃ A: 7% and C ₄ AF: 10%, raw meal rate values are KH=0.887, n=2.95, p=1.44, MgO content in clinker is 2.57%, phosphorus introduction in clinker is 0.6% P ₂ O ₅ , chemical composition of clinker See Table 3. According to the calculated ratio of raw materials, the raw materials are mixed and mixed evenly. The mixed raw materials are calcined in a high-temperature furnace at 1450°C and then quenched. The cooled clinker is crushed and ground, and the specific surface area of the clinker fineness is controlled to (340±20) m ² /kg by using Blaine specific surface area measuring instrument.

Table 3 Chemical composition of clinker

Figure 2 shows the diffraction peaks in the ranges of 32° to 33° and 51° to 52° of the local characteristic fingerprint of the prepared clinker sample Alite (the Cu K _α2 diffraction has been deducted). In the reference clinker sample C0, Alite has 3 branched small peaks between 32°-33°, and 2 branched small peaks at 51°-52°, which is the M3 crystal form. When 0.6% P ₂ O ₅ is introduced into the clinker, the position of the M3 crystal form corresponds to and ₍₂₂₄₎ crystal plane diffraction peaks disappear, only the R crystal form Crystal plane diffraction, the ₍₆₂₀₎ and ₍₀₄₀₎ crystal plane diffraction peaks that originally existed between 51-52° in the M3 crystal form also disappeared, and only the R-type ₍₂₂₀₎ crystal plane diffraction appeared, indicating that the C1 of Example 2 Alite in clinker is highly active R type.

According to GB/T17671-1999, the compressive strength test was carried out on the clinker samples. The water-cement ratio is 0.5, mixed with water to make a 40mm×40mm×40mm mortar test block, cured according to the standard, and its compressive strength was measured for 3 days, 7 days, 28 days and 90 days, see Table 4.

Table 4 Free calcium content, specific surface area and strength properties of clinker samples

Example 3:

According to the current chemical composition and mineral composition of China's benchmark clinker for cement, the design clinker mineral composition is C ₃ S: 60%, C ₂ S: 23%, C ₃ A: 7% and C ₄ AF: 10%, The ratio of raw material is KH=0.887, n=2.95, p=1.44, the content of MgO in the clinker is 2.56%, the amount of phosphorus introduced in the clinker is 1% P ₂ O ₅ ingredients, and the chemical composition of the clinker is shown in Table 5. According to the calculated ratio of raw materials, the raw materials are mixed and mixed evenly. The raw materials are calcined in a high-temperature furnace at 1450°C and then quenched. The cooled clinker is crushed and ground, and the specific surface area of the clinker fineness is controlled to (340±20) m ² /kg by using Blaine specific surface area measuring instrument.

Table 5 Chemical composition of clinker

According to GB/T17671-1999, the compressive strength test was carried out on the clinker samples. The water-cement ratio is 0.5, mixed with water to make a 40mm×40mm×40mm mortar test block, cured according to the standard, and its compressive strength was measured for 3 days, 7 days, 28 days and 90 days, see Table 6.

Table 6 Free calcium content, specific surface area and strength properties of clinker samples

Example 4:

According to the current chemical composition and mineral composition of China's benchmark clinker for cement, the design clinker mineral composition is C ₃ S: 60%, C ₂ S: 23%, C ₃ A: 7% and C ₄ AF: 10%, The ratio of raw meal is KH=0.887, n=2.95, p=1.44, the content of MgO in clinker is set to 2.59%, 2.58%, 2.55%, 0.50% and 1%, respectively, and the amount of phosphorus introduced in clinker is 0% P ₂ O ₅ , 0.3% P ₂ O ₅ , 1.5% P ₂ O ₅ , 1.0% P ₂ O ₅ and 0.6% P ₂ O ₅ , see Table 7 for the chemical composition of the clinker. According to the calculated ratio of raw materials, the raw materials are mixed and mixed evenly. The mixed raw materials are calcined in a high-temperature furnace at 1450°C and then quenched. The cooled clinker is crushed and ground, and the specific surface area of the clinker fineness is controlled to (340±20) m ² /kg by using Blaine specific surface area measuring instrument.

Table 7 Chemical composition of clinker samples

Fig. 3, Fig. 4, Fig. 5 and Fig. 6 respectively provide the diffraction peaks in the range of 32°～33° and 51°～52° of Alite’s local characteristic fingerprint in the prepared clinker samples (Cu K _α2 has been deducted diffraction). Sample E contains 2.58% MgO and a small amount of 0.3% P ₂ O ₅ , although The diffraction peaks of the two crystal planes of (224) and ₍₂₂₄₎ merge, but the dwarf shoulder peak on the right side of the ₍₆₂₀₎ diffraction peak between 51° and 52° corresponds to the ₍₀₄₀₎ diffraction peak of the monoclinic crystal form, indicating that in the E sample It is especially a mixed crystal form of monoclinic and R crystal forms. Sample F contains 2.55% MgO and high content of P ₂ O ₅ (1.5%), there are only two diffraction peaks at 32°-33°, and there is only one R-type ₍₂₂₀₎ crystal between 51-52° surface diffraction peaks, indicating that the Alite in the clinker is R-type, but because the content of P is too high, it is difficult to burn the clinker, and there is a certain amount of C ₂ S in the clinker, which leads to the existence of unsolidified Dissolved phosphate makes the early performance of clinker decline (see Table 8). Sample G contains a small amount of MgO (0.5%) and 1% P ₂ O ₅ , due to the solid solution of impurities such as Mg and P, the The crystal plane spacing is close to that of ₍₂₂₄₎ , resulting in the merger of the two crystal plane diffraction peaks, but the dwarf shoulder peak on the right side of the ₍₆₂₀₎ diffraction peak between 51° and 52° corresponds to the ₍₀₄₀₎ diffraction peak of the monoclinic crystal form , indicating that alite in the G sample is a mixed crystal form of monoclinic and R crystal forms. Example 4 (sample H) contains 1% MgO and 0.6% P ₂ O ₅ , there are only two diffraction peaks at 32°-33°, and there is only one R-type ⁽²²⁰⁾ crystal between 51-52° The surface diffraction peaks indicate that Alite in the clinker is R type.

According to GB/T17671-1999, the compressive strength test was carried out on the clinker samples. The water-cement ratio is 0.5, mixed with water to make a 40mm×40mm×40mm mortar test block, cured according to the standard, and its compressive strength was measured for 3 days, 7 days, 28 days and 90 days, see Table 8.

Table 8 Free calcium content, specific surface area and strength properties of clinker samples

The above embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and the protection scope of the present invention is defined by the claims. Those skilled in the art can make various modifications or equivalent replacements to the present invention within the spirit and protection scope of the present invention, and such modifications or equivalent replacements should also be deemed to fall within the protection scope of the present invention.

Claims (6)

1. A Portland cement clinker, characterized in that it contains trace amounts of magnesium and trace phosphorus, and R-type alite of 52% to 64% by weight, magnesium is 2.01% to 5% in terms of MgO, and phosphorus is in the amount of P ₂ O ₅ is calculated as 0.5% to 1.2%. 2. Portland cement clinker according to claim 1, is characterized in that, comprises following component, by weight percentage, Type R Alite: 52% to 64%; Belite: 14% to 26%; Tricalcium aluminate: 6% to 11%; Tetracalcium aluminoferrite: 9-15%; Free calcium oxide: 0~1.5%; The balance is other phases. 3. Portland cement clinker according to claim 1, characterized in that the weight percentage of R-type Alite is 54%-60%. 4. the preparation method of Portland cement clinker according to claim 1, is characterized in that, described method comprises the following steps: Step 1, selecting raw meal components according to the composition of the required cement clinker and determining the weight ratio of each raw meal component, the raw meal components include at least one magnesium-containing raw material, including at least one phosphorus-containing raw material; Step 2, fully mixing the above raw meal components, then calcining at high temperature, and rapidly cooling to room temperature to prepare cement clinker; In the cement clinker, the phosphorus content is calculated as the oxide P ₂ O ₅ , and the mass percentage is 0.5% to 1.2%. 5. The preparation method of Portland cement clinker according to claim 4, characterized in that the temperature range of high-temperature calcination is 1400°C-1500°C. The preparation method of Portland cement clinker according to claim 4, characterized in that the obtained cement clinker is ground, and the fineness of the sample is controlled until the specific surface area is 320-360 m ² /kg.