Method for preparing calcium sulphoaluminate modified Portland cement clinker based on single calcination

Abstract

The invention belongs to the field of material preparation, and particularly relates to a method for preparing calcium sulphoaluminate modified Portland cement clinker based on single calcination. The method comprises the following steps: a) grinding raw materials and sulfur-locking components according to the composition of raw material oxides, and uniformly mixing to obtain a powder cement raw material; and b) tabletting the powdery cement raw material, drying, preserving heat, calcining, taking out, quenching, grinding and sieving to obtain the C4A3 modified Portland cement clinker. The C4A3 modified Portland cement clinker is prepared by adopting a single-time high-temperature calcination method; a certain amount of sulfur locking component is introduced into the raw material, the sulfur locking component and C4A3 compete for SO3 to form sulfate or composite sulfate, and the decomposition temperature of the sulfur locking component is higher than that of C4A3, so that sulfur can be locked, and decomposition escape of the sulfur can be reduced; when the temperature is 1450 DEG C, the series of sulfates or composite sulfates start to release sulfur to form a certain amount of C4A3, namely, the sulfur is released at high temperature to promote the formation of C4A3, and the C4A3 modified Portland cement clinker can be sintered at high temperature with single property.

Description

Technical Field

[0001] The invention belongs to the field of material preparation, and in particular relates to a method for preparing calcium sulfoaluminate (C4A3$) modified silicate cement clinker based on single calcination. Background Art

[0002] C4A3$ has the characteristics of low firing temperature and good early mechanical properties. Therefore, introducing C4A3$ into silicate cement can reduce CO2 emissions, reduce energy consumption, and improve early mechanical properties. The existing preparation of C4A3$ modified silicate cement clinker can introduce trace elements Ba, the decomposition temperature of C4A3$ is increased by about 70°C, and barium calcium sulfoaluminate modified silicate clinker is synthesized at 1380°C. In addition, C4A3$ modified silicate cement clinker can also be successfully synthesized by secondary calcination. Although the existing preparation method synthesizes barium calcium sulfoaluminate modified silicate clinker, it is not efficient and consumes a lot of energy.

[0003] With the continuous development of cement industry, the consumption of high-quality limestone is increasing, and its storage capacity is gradually decreasing. Low-grade limestone has become the norm, among which high-alkali limestone is the most widespread. At the same time, a large amount of industrial solid waste residue is generated in the process of human industrial production. The increasing amount of these waste residues directly endangers human life safety, poses a serious threat to the environment and resources, and has a low utilization rate. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a method for preparing C4A3$ modified silicate cement clinker based on single calcination. The system can efficiently utilize high-alkali limestone and various solid wastes to produce clinker.

[0005] The technical solution adopted by the present invention to achieve the above-mentioned purpose is:

[0006] The present invention provides a method for preparing C4A3$ modified silicate cement clinker based on single calcination, comprising the following steps:

[0007] a) grinding the raw materials and the sulfur-locking component according to the raw material oxide composition, and mixing them uniformly to obtain powdered cement raw material;

[0008] b) Pressing the powdered cement raw material into tablets, drying and calcining at a temperature keeping warm, taking out and quenching, grinding and sieving, and obtaining C4A3$ modified silicate cement clinker.

[0009] Furthermore, in step a), the raw material oxide composition is, by percentage, CaO: 60-67%, SO3: 1-6%, SiO2: 18-26%, Al2O3: 5-10%, and Fe2O3: 3-8%.

[0010] Furthermore, the raw material composition percentage of low-grade / non-traditional raw materials of the cement clinker is: desulfurized gypsum: 2-5%, high-alkali limestone: 62-70%, medium-low-grade bauxite: 11-20%, steel slag tailings: 1-3%, antimony slag: 10-16%, fluorite: 1-2%

[0011] Furthermore, in step a), the sulfur-locking component is one or a combination of alkali metals, alkaline earth metals and transition metal elements, and its introduction amount accounts for 0.6-2.3% of the total amount of raw material oxides.

[0012] Furthermore, the sulfur-locking component is one or both of sodium carbonate and potassium carbonate.

[0013] Furthermore, in step b), the heat preservation calcination is carried out at 1450° C. for 30-45 minutes.

[0014] Furthermore, the system of the C4A3$ modified silicate cement clinker prepared by the present invention is: C3S 50%, C2S 25%, C3A 10%, C4AF 8%, C4A3$ 7%.

[0015] Furthermore, the KH of the C4A3$ modified silicate cement clinker is 0.9±0.1, SM is 1.7±0.3, and IM is 3.0±0.5.

[0016] The present invention provides a method for preparing C4A3$ modified silicate cement clinker by a single calcination process, wherein a certain amount of sulfur-locking component is introduced into the raw material, and the sulfur-locking component competes with C4A3$ for SO3 to form sulfate or composite sulfate, which can lock sulfur and reduce its decomposition and escape, that is, low-temperature sulfur locking forms a series of sulfates or composite sulfates; when the temperature is 1450°C, the series of sulfates or composite sulfates begin to release sulfur to form a certain amount of C4A3$, that is, high-temperature sulfur release promotes the formation of C4A3$, and C4A3$ modified silicate cement clinker can be calcined at a single high temperature.

[0017] Compared with the prior art, the C4A3$ modified silicate cement clinker and the preparation method thereof of the present invention have the following beneficial effects:

[0018] (1) The present invention adopts a single high-temperature calcination method to successfully prepare C4A3$ modified silicate cement clinker at 1450°C; the method provided by the present invention solves the technical problem of large energy consumption caused by secondary calcination in the prior art;

[0019] (2) The present invention introduces a certain amount of sulfur-locking components into the raw material. The sulfur-locking components compete with C4A3$ for SO3 to form sulfate or composite sulfate. Since the decomposition temperature of the sulfur-locking components is higher than that of C4A3$, the sulfur can be locked to reduce its decomposition and escape, that is, low-temperature sulfur locking forms a series of sulfates; when the temperature reaches 1450°C, the series of sulfates or composite sulfates begin to release sulfur to form a certain amount of C4A3$, that is, high-temperature sulfur release promotes the formation of C4A3$, and the C4A3$ modified silicate cement clinker can be calcined at high temperature;

[0020] (3) The present invention utilizes multiple solid wastes to prepare C4A3$ modified silicate cement clinker. The production of this type of clinker can not only reduce resource consumption, reduce production costs, and reduce environmental pollution, but also improve the utilization rate of solid wastes, generate benefits, and has great potential. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments.

[0022] The experimental raw materials used in the present invention include desulfurized gypsum, high-alkali limestone, medium-low-grade bauxite, steel slag tailings and antimony slag. The compositions of the raw materials used in Examples 1, 2 and 3 are shown in Table 1.

[0023] Table 1 Chemical composition of experimental raw materials (%)

[0024]

[0025] Example 1

[0026] An alite sulphoaluminate cement clinker mineral has KH=0.90, SM=1.96, and IM=2.56.

[0027] The specific preparation method is as follows:

[0028] Calculate and weigh the raw materials according to the rate value, grind the raw material and 0.6% sulfur-locking component (sodium carbonate) into fine powder, mix them evenly, and obtain cement raw material powder. Press the raw material into a size of The round cake sample pieces are dried, then calcined in a high-temperature furnace, kept at 1420℃ for 45 minutes, taken out and quenched, and ground to obtain cement clinker.

[0029] Example 2

[0030] A kind of alite sulphoaluminate cement clinker mineral has KH=0.88, SM=1.68, IM=3.04

[0031] The specific preparation method is as follows:

[0032] Calculate and weigh the raw materials according to the rate value, grind the raw material and 1.2% sulfur-locking component (sodium carbonate) into fine powder, mix them evenly, and obtain cement raw material powder. Press the raw material into a size of The round cake sample pieces are dried, then calcined in a high-temperature furnace, kept at 1430°C for 30 minutes, taken out and quenched, and ground to obtain cement clinker.

[0033] Example 3

[0034] A kind of alite sulphoaluminate cement clinker mineral has KH=0.86, SM=1.53, IM=3.43

[0035] The specific preparation method is as follows:

[0036] Calculate and weigh the raw materials according to the rate value, grind the raw material and 2.3% sulfur-locking component (potassium carbonate) into fine powder, mix them evenly, and obtain cement raw material powder. Press the raw material into a size of The round cake sample pieces are dried, then calcined in a high-temperature furnace, kept at 1450°C for 45 minutes, taken out and quenched, and ground to obtain cement clinker.

[0037] It is worth noting that when the raw material composition provided in Examples 1-3 is calcined, if the sulfur-locking component is not added to the raw material, sulphoaluminate-modified silicate clinker cannot be prepared at a temperature of 1420°C-1450°C.

[0038] Effect Example

[0039] The above-obtained clinker was fully ground on a planetary ball mill to a certain fineness, passed through a 200-mesh sieve, and the residue on the sieve was controlled at 0.2%-5%. According to a water-cement ratio of 0.3-0.35, 8% of dihydrate gypsum was added, and cement paste was prepared using a cement paste mixer. 3 The mold was formed and the samples were cured in a room at room temperature for 24 hours before demolding. Then, the samples prepared in each embodiment were placed in a curing box and cured for 3 days, 7 days, and 28 days under standard conditions of constant temperature and humidity. The compressive strength tests were performed respectively. The specific results are shown in Table 2.

[0040] Table 2 Mechanical properties of samples at different ages

[0041]

Claims

1. A method for preparing C4A3$ modified silicate cement clinker based on single calcination, characterized in that: The following steps are involved: a) grinding the raw materials and the sulfur-locking component according to the raw material oxide composition, and mixing them uniformly to obtain powdered cement raw material; b) Pressing the powdered cement raw material into tablets, drying and calcining at a temperature keeping warm, taking out and quenching, grinding and sieving, and obtaining C4A3$ modified silicate cement clinker.

2. The method according to claim 1, characterized in that In step a), the raw material oxide composition is as follows, by percentage: CaO: 60-67%, SO3: 1-6%, SiO2: 18-26%, Al2O3: 5-10%, Fe2O3: 3-8%.

3. The method according to claim 2, characterized in that The raw materials of the cement clinker are composed of low-grade / non-traditional raw materials in percentages: desulfurized gypsum: 2-5%, high-alkali limestone: 62-70%, medium-low-grade bauxite: 11-20%, steel slag tailings: 1-3%, antimony slag: 10-16%, and fluorite: 1-2%.

4. The method according to claim 1 or 2, characterized in that: In step a), the sulfur-locking component is one or a combination of alkali metals, alkaline earth metals and transition metal elements, and its introduction amount accounts for 0.6-2.3% of the total amount of raw material oxides.

5. The method according to claim 1 or 4, characterized in that: The sulfur-locking component is one or two of sodium carbonate and potassium carbonate.

6. The method according to any one of claims 1 to 5, characterized in that: In step b), the heat preservation calcination is carried out at 1450° C. for 30-45 minutes.

7. The method according to any one of claims 1 to 6, characterized in that: The system of the C4A3$ modified silicate cement clinker is: C3S 50%, C2S 25%, C3A 10%, C4AF 8%, C4A3$ 7%.

8. The method according to any one of claims 1 to 7, characterized in that: The KH of the C4A3$ modified silicate cement clinker is 0.9±0.1, SM is 1.7±0.3, and IM is 3.0±0.5.

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