A high-strength slow-setting portland cement clinker and a method for preparing the same

Abstract

The application discloses a kind of high-strength slow-setting silicate cement clinker and preparation method thereof, its mineral composition includes C3S>63%, C2S 1.09%‑13.39%, C3A<4.7%, C4AF 13.73%‑14.36%, free calcium oxide content in clinker is below 1.5%.The application reduces aluminum rate from the angle of mineral composition design, improves limestone saturation coefficient, and prepares a kind of low alumina tricalcium (C3A<4.7%), high silicate tricalcium (C3S>63%) clinker using industrial solid waste coal gangue, which can be prepared under existing cement production process, and has the characteristics of high strength, stable expansion and shrinkage performance, low early hydration heat release, long setting time and easy to control, etc.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of civil engineering materials, and particularly relates to a high-strength slow-setting Portland cement clinker and a preparation method thereof. BACKGROUND

[0002] Tricalcium aluminate has high reactivity, and when the content of tricalcium aluminate in the clinker is high, the clinker is easy to react with moisture in the air, so that the storage and transportation conditions are more harsh. The content of tricalcium aluminate in the existing ordinary Portland clinker is generally in the range of 6%-8%, and instant setting phenomenon generally occurs when the clinker is mixed, which is not conducive to transportation and construction. Although the setting time can be prolonged by adding gypsum or retarder, the transportation time is still insufficient for remote areas where the distance between the mixing station and the construction site is too large. On the other hand, existing studies have shown that the clinker with high tricalcium aluminate has poor adaptability to additives, resulting in low adjustment efficiency of the additives and high input cost, while the clinker with low tricalcium aluminate has low early strength, which is not conducive to construction. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a low-tricalcium-aluminate high-Portland-clinker, which can be prepared under the existing cement production process and has the characteristics of high strength, stable expansion and shrinkage performance, low early hydration heat, long setting time, easy to control, and the like, while avoiding the poor adaptability of the additive to the clinker and the resulting engineering application problems.

[0004] In order to achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows:

[0005] A high-strength slow-setting Portland cement clinker, which has a mineral composition comprising the following components in terms of mass percentage:

[0006] C3S>63%, C2S 1.09%-13.39%, C3A <4.7%, C4AF 13.73%-14.36%, and the content of free calcium oxide in the clinker is below 1.5%.

[0007] Preferably, the mineral composition of the high-strength slow-setting Portland cement clinker of the present application comprises the following components in terms of mass percentage:

[0008] C3S 63.49%-76.36%, C2S 1.09%-13.39%, C3A 4.64%-4.68%, C4AF 13.73%-14.36%, and the content of free calcium oxide in the clinker is below 1.5%.

[0009] Further, the high-strength slow-setting silicate cement clinker of the present application is prepared by calcining raw materials, which include the following components in the following mass percentages: limestone in an amount of 80.11%-81.04%, sandstone in an amount of 10.58%-9.79%, coal gangue in an amount of 7.75%-7.73%, and non-ferrous metal slag in an amount of 1.56%-1.44%.

[0010] Further, the lime saturation factor of the clinker is between 0.934 and 0.999, the silicon ratio is between 2.23 and 2.26, and the aluminum ratio is between 1.01 and 1.04.

[0011] Further, the present application also provides a preparation method of the high-strength slow-setting silicate cement clinker, which includes the following steps:

[0012] (1) preparing raw materials: taking limestone in an amount of 80.11%-81.04% of the total mass of the raw materials, sandstone in an amount of 10.58%-9.79% of the total mass of the raw materials, coal gangue in an amount of 7.75%-7.73% of the total mass of the raw materials, and non-ferrous metal slag in an amount of 1.56%-1.44% of the total mass of the raw materials, and fully mixing them uniformly; the lime saturation factor is between 0.934 and 0.999, the silicon ratio is between 2.23 and 2.26, and the aluminum ratio is between 1.01 and 1.04;

[0013] (2) clinker calcination: calcining the raw materials prepared in step (1) at 1450°C to obtain the clinker.

[0014] Preferably, in step (1), the content of titanium element in the raw materials is in the range of 0.33%-0.35% in terms of TiO2, which promotes the formation of belite minerals in the calcination process.

[0015] Preferably, in step (1), the content of magnesium element in the raw materials is in the range of 1.19%-1.24% in terms of MgO, which promotes the combination of C2S and f-CaO to generate C3S in the calcination process.

[0016] Preferably, in step (1), the content of sulfur element in the raw materials is in the range of 0.44%-0.46% in terms of SO3, which promotes the formation of alite minerals in the calcination process.

[0017] Further, in step (2), the calcination system is as follows: heating at a rate of 5-15°C / min, heating to 900°C and keeping for 30-60 min, then heating to 1450°C at a rate of 5-15°C / min and keeping for 30-60 min, and finally cooling to room temperature at a rate of 60-100°C / min.

[0018] Preferably, in step (2), the firing system is to heat up to 900℃ at a rate of 10℃ / min, keep for 30min, then heat up to 1450℃ at a rate of 10℃ / min, keep for 60min, and then cool down to room temperature at a rate of 80℃ / min.

[0019] Advantages:

[0020] (1) The present application reduces the aluminum rate and improves the limestone saturation coefficient from the perspective of mineral composition design, and a low aluminate tricalcium (C3A <4.7%) and high silicate tricalcium (C3S >63%) clinker is prepared from industrial solid waste coal gangue. This clinker can be prepared under existing cement production process conditions and has the characteristics of high strength, stable expansion and shrinkage performance, low early hydration heat, long setting time, etc. The clinker has the characteristics of large degree of freedom in setting time adjustment and setting time adjustment by adding desulfurization gypsum only, low adjustment cost and avoidance of poor adaptability of additives and clinker and other problems caused thereby, and is suitable for scenarios where the distance between the mixing station and the construction site is too long.

[0021] (2) The present application is aimed at the main provider of early strength and heat release of alite and aluminate tricalcium cement clinker, and by adjusting the proportion of clinker minerals, the fired clinker has the advantages of low early hydration heat, good volume stability, and high 28d strength.

[0022] (3) The raw materials for the high alite content portland cement clinker of the present application are easy to obtain, the method is simple and has strong universality. In actual production, coal gangue can be used as the source of aluminum, increasing the comprehensive utilization value of industrial byproducts. The source of magnesium can be taken from limestone, without additional addition of ingredients, convenient operation, and without increasing the production cost. The present application uses coal gangue, non-ferrous metal slag and other solid wastes to prepare raw materials, and introduces a certain amount of impurity ions such as titanium, sodium and potassium, so that the high alite clinker can be fired under conventional industrial conditions.

[0023] (4) The high alite portland cement clinker prepared by the present application has a long initial setting time, and after mixing with water, there is no phenomenon of rapid setting, flash setting, etc., which is convenient for construction and long-distance transportation. After adding gypsum, the hydration reaction of minerals in the clinker system can be accelerated, the generation of hydration products can be promoted, and a significant setting accelerating effect can be achieved. BRIEF DESCRIPTION OF DRAWINGS

[0024] The above and / or other aspects of the present application will become apparent and more readily appreciated from the following description, taken in conjunction with the accompanying drawings, in which:

[0025] Figure 1 is the XRD diffraction pattern of the clinker of each embodiment and the clinker of the comparative example.

[0026] Figure 2is a graph showing the strength comparison of each example clinker and comparative clinker.

[0027] Figure 3 is a graph showing the linear shrinkage and expansion rate comparison of each example clinker and comparative clinker.

[0028] Figure 4 is a graph showing the cumulative heat release of each example clinker and comparative clinker.

[0029] Figure 5 is a graph showing the cumulative heat release of each example clinker and comparative clinker after adding gypsum.

[0030] Figure 6 is a graph showing the initial setting time of each example clinker and cement.

[0031] Figure 7 is a graph showing the initial setting time and final setting time of each example clinker and cement.

[0032] Figure 8 is a graph showing the influence of the amount of different gypsum on the initial setting time of the example clinker and comparative clinker. DETAILED DESCRIPTION

[0033] The present application can be better understood according to the following examples.

[0034] In the following examples, the test methods used include:

[0035] The hydration heat release data was tested by TAM Air 8 channel measuring instrument using internal stirring method, and the test conditions were w / c = 0.4 and temperature of 20℃.

[0036] The mineral content in the clinker was calculated using Bogue method.

[0037] The clinker strength test was performed according to national standard GB / T 17671-1999.

[0038] The specific surface area determination was performed according to national standard GB / T 8074-2008.

[0039] The setting time was referred to GB / T 1346-2011, and the fixed water-cement ratio w / c = 0.4.

[0040] The shrinkage and expansion rate was performed according to JC / T 313-2009.

[0041] In the following examples, the chemical composition of the raw material is shown in Table 1.

[0042] Table 1 Chemical composition of raw material (wt / %)

[0043]

[0044] Example 1

[0045] The raw meal was prepared by using limestone, sandstone, coal gangue and non-ferrous metal slag, and the raw meal was proportioned and mixed uniformly according to the raw material ratio. The raw meal chemical analysis table is shown in Table 1.

[0046] The calcination stage was heated at 10 ℃ / min to 900 ℃, and then kept for 30 min. Then it was heated at 10 ℃ / min to 1450 ℃, and kept for 60 min. Then it was cooled to room temperature at a cooling rate of 60-100 ℃ / min. The sintered clinker was ground to a powder with a specific surface area of 350-370 m 2 / kg. The sintered clinker chemical composition is shown in Table 2, the clinker mineral composition and rate value is shown in Table 3, and the sintered clinker XRD pattern is shown in Figure 1 The MgO content of the clinker in Example 1 was 1.73%, the SO3 content of the clinker was 0.51%, and the TiO2 content of the clinker was 0.53%.

[0047] Example 2

[0048] The raw meal was prepared by using limestone, sandstone, coal gangue and non-ferrous metal slag, and the raw meal was proportioned and mixed uniformly according to the raw material ratio. The raw meal chemical analysis table is shown in Table 1. Then the mixed raw meal was calcined, sintered and ground under the same conditions as in Example 1. The sintered clinker chemical composition is shown in Table 2, the clinker mineral composition and rate value is shown in Table 3, and the sintered clinker XRD pattern is shown in Figure 1 The MgO content of the clinker in Example 2 was 1.75%, the SO3 content of the clinker was 0.50%, and the TiO2 content of the clinker was 0.53%.

[0049] Example 3

[0050] The raw meal was prepared by using limestone, sandstone, coal gangue and non-ferrous metal slag, and the raw meal was proportioned and mixed uniformly according to the raw material ratio. The raw meal chemical analysis table is shown in Table 1. Then the mixed raw meal was calcined, sintered and ground under the same conditions as in Example 1. The sintered clinker chemical composition is shown in Table 2, the clinker mineral composition and rate value is shown in Table 2, and the sintered clinker XRD pattern is shown in Figure 1 The MgO content of the clinker in Example 3 was 1.72%, the SO3 content of the clinker was 0.42%, and the TiO2 content of the clinker was 0.53%.

[0051] Comparative Example

[0052] The ordinary Portland cement clinker (OPC) of a certain enterprise in Jiangsu was used as a comparative example. The blocky clinker was ground to a powder with a specific surface area of 350-370 m 2 / kg. The clinker chemical composition is shown in Table 2, the clinker mineral composition and rate value is shown in Table 3, and the clinker XRD pattern is shown in Figure 1 .

[0053] Table 2. Chemical composition of clinker (wt / %)

[0054]

[0055] Table 3. Clinker mineral content (wt / %) and rate values

[0056]

[0057] Figure 1 These are the XRD diffraction patterns of the clinker and OPC clinker of each embodiment. It can be seen from the patterns that the C3A diffraction peak of Examples 1-3 is much lower than that of the OPC clinker sample.

[0058] Figure 2 The chart shows a comparison of the strength of clinker and OPC in each embodiment. It can be seen that the 3d strength of each embodiment is higher than 20MPa, and the 28d strength of embodiment 3 is higher than that of the comparative OPC, reaching more than 80MPa.

[0059] Figure 3 The graph shows a comparison of the linear shrinkage and expansion rates of clinker and OPC in each embodiment. It can be seen that the linear expansion rates of embodiments 1-3 within 28 days are all lower than those of the comparative embodiment. This indicates that the volume change of the clinker in the embodiments is more stable and less prone to cracking compared to ordinary silicate clinker.

[0060] Figure 4 and Figure 5 These are hydration exothermic curves of clinker and OPC in each embodiment. From Figure 4 The cumulative heat release graph of clinker shows that in the early stage of hydration (before 30 hours), the cumulative heat release of Examples 1-3 is much lower than that of the comparative example. This indicates that the early reaction of the examples is relatively slow. The experimental phenomena such as the amount of bubbles generated after adding water and mixing in the examples being much lower than that of the comparative sample also prove this point, indicating that the clinker slurry of each example is denser and has better volume stability.

[0061] Depend on Figure 5 The cumulative heat release graph of cement shows that after adding 5% desulfurized gypsum, the heat release in the early stage (20 hours ago) of the example is significantly increased, which leads to a significant change in the setting time of the example. However, compared with the comparative example, the cumulative heat release within 3 days is lower, indicating that the cement paste of each example is denser and has better volume stability.

[0062] Depend on Figure 6The cement initial setting time column chart of clinker can be seen that, under the same water-cement ratio condition (w / c = 0.4), the time of the slurry of the clinker of the examples to reach the initial setting state is more than 600 min, and the example 2 is even close to 800 min, which shows that the slurry of the clinker of the examples has several times of transportation and construction time compared with the comparative examples. In addition, the cement prepared by adding the desulfurization gypsum to the ordinary portland clinker (OPC) shows the slow setting, while the clinkers of the examples 1-3 show the obvious acceleration of setting after adding the gypsum. The difference of the initial setting time of the comparative examples and the examples 1-3 is within 100 min after adding the gypsum, which shows that the setting time of the slurry of the clinker of the examples can be regulated by the gypsum, and the effect is obvious.

[0063] From the above data, it can be seen that the clinker of the examples has the slow setting property, and the setting time can be regulated by the gypsum. Figure 7 The cement initial setting-ultimate setting floating column chart of clinker can be seen that, the difference of the time of the slurry of the clinker of the examples 1-3 to reach the initial setting and the ultimate setting state is much larger than that of the comparative examples, which may have a certain influence on the construction, but the difference of the time of the cement slurry prepared by adding the gypsum to the clinkers of the examples 1-3 to reach the initial setting and the ultimate setting state is smaller than that of the comparative examples. Combined with the hydration heat release chart, it shows that the clinker of each example can effectively regulate the setting time with the addition of the gypsum, which is very beneficial to the construction.

[0064] From the above data, it can be seen that the clinker of the examples has the slow setting property, and the setting time can be regulated by the gypsum. Figure 8 The influence relationship chart of the amount of different gypsum on the initial setting time of the clinker of the examples and the comparative examples can be seen that, the initial setting time of the comparative examples is prolonged when adding different amounts of gypsum, but there is no obvious change rule, while under the same gypsum addition amount, the initial setting time of the examples 1-3 has an obvious change rule when adding different amounts of gypsum, which specifically shows that the initial setting time is gradually shortened with the increase of the gypsum addition amount, and even under a certain gypsum addition amount (7wt%), the initial setting time of the example 3 is smaller than that of the comparative examples.

[0065] The present application provides a kind of high-strength slow-setting portland cement clinker and its preparation method, and the method and approach for realizing the technical scheme are many, the above-mentioned is only preferred embodiment of the present application, it should be pointed out that, for the ordinary skilled person in the art, without departing from the principle of the present application, can make a number of improvements and refinements, these improvements and refinements should be regarded as the protection scope of the present application. The components not specified in the embodiment can be realized by the prior art.

Claims

1. A high-strength, slow-setting Portland cement clinker, characterized in that, The mineral composition thereof comprises the following components in percentage by mass: C3S >63%, C2S 1.09%-13.39%, C3A <4.7%, C4AF 13.73%-14.36%, the free lime content in the clinker is below 1.5%; The raw material comprises the following components in percentage by mass: limestone 80.11%, sandstone 10.58%, coal gangue 7.75%, non-ferrous metal ash residue 1.56%; The lime saturation factor for clinker firing is between 0.934-0.999, the silicon ratio is between 2.23-2.26, and the aluminum ratio is between 1.01-1.

04.

2. The high-strength, slow-setting Portland cement clinker according to claim 1, characterized in that, The mineral composition thereof comprises the following components in percentage by mass: C3S 63.49%-76.36%, C2S 1.09%-13.39%, C3A 4.64%-4.68%, C4AF 13.73%-14.36%, the free lime content in the clinker is below 1.5%.

3. The process for the production of high strength slow setting Portland cement clinker as claimed in claim 1, wherein, The method comprises the following steps: (1) preparing raw material: taking limestone of 80.11% of the total mass of the raw material, sandstone of 10.58% of the total mass of the raw material, coal gangue of 7.75% of the total mass of the raw material, and non-ferrous metal ash residue of 1.56% of the total mass of the raw material, and fully mixing them uniformly; the lime saturation factor is between 0.934-0.999, the silicon ratio is between 2.23-2.26, and the aluminum ratio is between 1.01-1.04; (2) clinker calcination: calcining the raw material prepared in step (1) at 1450℃, and obtaining the clinker.

4. The method of producing a high-strength slow-setting Portland cement clinker according to claim 3, characterized by, In step (1), the titanium element content in the raw material is 0.33%-0.35% in percentage by mass as TiO2.

5. The method of producing a high-strength slow-setting Portland cement clinker according to claim 3, characterized by, In step (1), the magnesium element content in the raw material is 1.19%-1.24% in percentage by mass as MgO.

6. The method of producing a high-strength slow-setting Portland cement clinker according to claim 3, characterized by, In step (1), the sulfur element content in the raw material is 0.44%-0.46% in percentage by mass as SO3.

7. The method of producing high-strength slow-setting Portland cement clinker according to claim 3, characterized by, In step (2), the firing system is as follows: heating at a rate of 5-15℃ / min, heating to 900℃ and keeping for 30-60min, then heating to 1450℃ at a rate of 5-15℃ / min, keeping for 30-60min, and finally cooling to room temperature.

8. The method of producing high-strength slow-setting Portland cement clinker according to claim 3, characterized by, In step (2), the firing system is as follows: heating at a rate of 10℃ / min, heating to 900℃ and keeping for 30min, then heating to 1450℃ at a rate of 10℃ / min, keeping for 60min, and finally cooling to room temperature at a rate of 80℃ / min.

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