METHOD FOR PREPARING CEMENT CLINKER UNDER OXYGEN-RICH COMBUSTION CONDITION AND CEMENT MATERIAL

Abstract

The present application belongs to the technical field of a cement material, and specifically relates to a method for preparing cement clinker and a cement material. The method for preparing cement clinker provided by the present application comprises the following steps: 1) preparing cement raw meal; 2) calcining the cement raw meal under an oxygen-rich atmosphere, the oxygen-rich atmosphere being mixed gas of oxygen and carbon dioxide in a volume ratio of (0.21-0.61):(0.39-0.79). The method for preparing the cement clinker of the present application is not easy to generate the pollutant NO.sub.x, the main component in the flue gas is CO.sub.2, which is more conducive to carbon capture and sequestration, and the cement clinker obtained has a high content of C.sub.3S, and the cement clinker has good performance (hydration effect and stability).

Claims

1. A method for preparing cement clinker, comprising the following steps: 1) preparing cement raw meal; and 2) calcining the cement raw meal under an oxygen-rich atmosphere, the oxygen-rich atmosphere being mixed gas of oxygen and carbon dioxide in a volume ratio of (0.21-0.61):(0.39-0.79).

2. The method of claim 1, wherein the volume percentage of oxygen in the oxygen-rich atmosphere in step 2) is in a range from 21% to 50%.

3. The method of claim 2, wherein the volume percentage of oxygen in the oxygen-rich atmosphere in step 2) is 31% or 41%.

4. The method of claim 1, wherein the calcining in step 2) is performed at a temperature ranging from 1,430 C. to 1,470 C. for a time period ranging from 45 min to 75 min.

5. The method of claim 1, wherein the composition of the raw materials of the cement raw meal in step 1) comprises the following by weight: 75-85 parts of limestone, 5-15 parts of coal-fired slag, 1-5 parts of iron tailings and 5-10 parts of gas ash.

6. The method of claim 5, wherein the composition of the raw materials of the cement raw meal in step 1) further comprises fly ash; and the fly ash is added in an amount of 0.8% to 4% of the total mass of the raw materials of the cement raw meal.

7. Cement clinker prepared by the method for preparing cement clinker as claimed in claim 1.

8. The cement clinker of claim 7, wherein the cement clinker comprises the following mineral phases by mass percentage: 58% to 70% of C.sub.3S, 10% to 17% of C.sub.2S, 2.0% to 2.7% of C.sub.3A, 17% to 23% of C.sub.4AF, and miscellaneous mineral phases as a balance.

9. The cement clinker of claim 8, wherein the cement clinker comprises the following mineral phases by mass percentage: 69.1% of C.sub.3S, 11.4% of C.sub.2S, 2.0% of C.sub.3A, 17.4% of C.sub.4AF, and miscellaneous mineral phases as a balance; or, the cement clinker comprises the following mineral phases by mass percentage: 63.3% of C.sub.3S, 14.2% of C.sub.2S, 2.0% of C.sub.3A, 20.4% of C.sub.4AF and miscellaneous mineral phases as a balance.

10. A cement material comprising the cement clinker as claimed in claim 7.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or prior art, the accompanying drawings need to be used in the description of the specific embodiments or prior art will be briefly introduced below, and it will be obvious that the accompanying drawings in the following description are some of the embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to these drawings without creative labor.

[0028] FIG. 1 shows a comparison of XRD patterns of cement clinker from Examples 1-5 and Comparative Example 1 of the present application;

[0029] FIG. 2 shows a comparison of the mass contents of free calcium oxide (f-CaO) in cement clinker from Examples 1-5 and Comparative Example 1 of the present application;

[0030] FIG. 3 shows a comparison of the compressive strength at day 3 and day 28 of the cement of the present application containing the cement clinker of Examples 1-5 and Comparative Example 1;

[0031] FIG. 4 shows a comparison of cement clinker from Example 1 (A1), Example 2 (A2) and Comparative Example 1 (A0) of the present application under a polarizing microscope (where Alite means Alite crystals, and Belite means Belite crystals);

[0032] FIG. 5 shows a comparison of cement clinker from Example 3 (A3), Example 4 (A4) and Example 5 (A5) of the present application under a polarizing microscope (where Alite means Alite crystals, and Belite means Belite crystals);

[0033] FIG. 6 shows a comparison of hydrated cement clinker from Example 1 (A1), Example 2 (A2) and Comparative Example 1 (A0) of the present application under a scanning electron microscope; and

[0034] FIG. 7 shows a comparison of hydrated cement clinker from Example 3 (A3), Example 4 (A4) and Example 5 (A5) of the present application under a scanning electron microscope.

DETAILED DESCRIPTION OF THE INVENTION

[0035] The following examples are provided for a better and further understanding of the present application, and are not limited to the best embodiments described, and do not constitute a limitation on the content and scope of protection of the present application, and any product identical or similar to the present application derived by any person under the inspiration of the present application or by combining the features of the present application with those of other prior art will fall within the scope of protection of the present application.

[0036] Where specific experimental steps or conditions are not indicated in the examples, the operations or conditions of conventional experimental steps described in the literature in the field can be performed. Where no manufacturer is indicated for the reagents or instruments used, the reagents or instruments used are conventional reagent and products that can be obtained through market purchase.

[0037] The composition of the limestone used in the examples and comparative examples of the present application includes: 48.24% of CaO, 5.76% of SiO.sub.2, 1.46% of Al.sub.2O.sub.3, 0.70% of Fe.sub.2O.sub.3, 1.78% of MgO, 0.30% of SO.sub.3, 0.43% of K.sub.2O, 0.08% of Na.sub.2O, and 41.25% of loss-on-ignition.

[0038] The composition of coal-fired slag includes: 5.17% of CaO, 62.01% of SiO.sub.2, 21.87% of Al.sub.2O.sub.3, 4.13% of Fe.sub.2O.sub.3, 0.26% of MgO, 0.03% of SO.sub.3, 2.56% of K.sub.2O, 1.07% of Na.sub.2O, and 2.90% of loss-on-ignition.

[0039] The composition of iron tailings includes: 2.02% of CaO, 79.41% of SiO.sub.2, 3.20% of Al.sub.2O.sub.3, 9.77% of Fe.sub.2O.sub.3, 2.04% of MgO, 0.28% of SO.sub.3, 0.59% of K.sub.2O, 0.23% of Na.sub.2O, and 2.46% of loss-on-ignition; and its source comes from Anshan Jinhe Mining Co., Ltd.

[0040] The composition of gas ash includes: 5.43% of CaO, 10.37% of SiO.sub.2, 5.75% of Al.sub.2O.sub.3, 34.96% of Fe.sub.2O.sub.3, 1.59% of MgO, 0.13% of SO.sub.3, 0.91% of K.sub.2O, 0.39% of Na.sub.2O, and 40.48% of loss-on-ignition.

Example 1

[0041] This example provided a method for preparing cement clinker, comprising the following steps: [0042] 1) preparing cement raw meal by mixing 81.34% of limestone, 7.94% of coal-fired slag, 1.98% of iron tailings, 7.93% of gas ash and 0.81% of fly ash according to the raw material composition of the cement raw meal, wherein the fly ash was obtained by combusting pulverized coal of bituminous coal to 815 C., and the powder of limestone, coal-fired slag, iron tailings, gas ash and fly ash had an 80 m sieve residue of 5%; and [0043] 2) calcining the cement raw meal under an oxygen-rich atmosphere to obtain the cement clinker, wherein the oxygen-rich atmosphere was mixed gas of oxygen and carbon dioxide with a volume ratio of 0.61:0.39, the calcining was performed at a temperature of 1,450 C. for a time period of 75 min.

Example 2

[0044] This example provided a method for preparing cement clinker, which differed from Example 1 only in that the oxygen-rich atmosphere in step 2) was mixed gas of oxygen and carbon dioxide in a volume ratio of 0.51:0.49.

Example 3

[0045] This example provided a method for preparing cement clinker, which differed from Example 1 only in that the oxygen-rich atmosphere in step 2) was mixed gas of oxygen and carbon dioxide in a volume ratio of 0.41:0.59.

Example 4

[0046] This example provided a method for preparing cement clinker, which differed from Example 1 only in that the oxygen-rich atmosphere in step 2) was mixed gas of oxygen and carbon dioxide in a volume ratio of 0.31:0.69.

Example 5

[0047] This example provided a method for preparing cement clinker, which differed from Example 1 only in that the oxygen-rich atmosphere in step 2) was mixed gas of oxygen and carbon dioxide in a volume ratio of 0.21:0.79.

Example 6

[0048] This example provided a method for preparing cement clinker, which differed from Example 1 only in that the oxygen-rich atmosphere in step 2) was mixed gas of oxygen and carbon dioxide in a volume ratio of 0.41:0.59, and the calcining was performed at 1,430 C. for 75 min.

Example 7

[0049] This example provided a method for preparing cement clinker, which differed from Example 1 only in that the oxygen-rich atmosphere in step 2) was mixed gas of oxygen and carbon dioxide in a volume ratio of 0.31:0.69, and the calcining was performed at 1,430 C. for 60 min.

Example 8

[0050] This example provided a method for preparing cement clinker, which differed from Example 1 only in that the oxygen-rich atmosphere in step 2) was mixed gas of oxygen and carbon dioxide in a volume ratio of 0.21:0.79, and the calcining was performed at 1,430 C. for 75 min.

Example 9

[0051] This example provided a method for preparing cement clinker, which differed from Example 1 only in that the oxygen-rich atmosphere in step 2) was mixed gas of oxygen and carbon dioxide in a volume ratio of 0.41:0.59, and the calcining was performed at 1,450 C. for 45 min.

Example 10

[0052] This example provided a method for preparing cement clinker, which differed from Example 1 only in that the oxygen-rich atmosphere in step 2) was mixed gas of oxygen and carbon dioxide in a volume ratio of 0.21:0.79, and the calcining was performed at 1,450 C. for 45 min.

Example 11

[0053] This example provided a method for preparing cement clinker, which differed from Example 1 only in that the oxygen-rich atmosphere in step 2) was mixed gas of oxygen and carbon dioxide in a volume ratio of 0.61:0.39, and the calcining was performed at 1,450 C. for 60 min.

Example 12

[0054] This example provided a method for preparing cement clinker, which differed from Example 1 only in that the oxygen-rich atmosphere in step 2) was mixed gas of oxygen and carbon dioxide in a volume ratio of 0.51:0.49, and the calcining was performed at 1,450 C. for 60 min.

Example 13

[0055] This example provided a method for preparing cement clinker, which differed from Example 1 only in that the oxygen-rich atmosphere in step 2) was mixed gas of oxygen and carbon dioxide in a volume ratio of 0.31:0.69, and the calcining was performed at 1,470 C. for 45 min.

Example 14

[0056] This example provided a method for preparing cement clinker, which differed from Example 1 only in that the oxygen-rich atmosphere in step 2) was mixed gas of oxygen and carbon dioxide in a volume ratio of 0.41:0.59, and the calcining was performed at 1,470 C. for 60 min.

Comparative Example 1

[0057] This comparative example provided a method for preparing cement clinker, which differed from Example 1 only in that in step 2), the cement raw meal was placed in a silicon-molybdenum furnace in which the atmosphere can be adjusted, and the calcining was performed under an air atmosphere at 1,450 C. for 75 min to obtain the cement clinker.

Test Example 1

[0058] The D8 Advance X-ray diffractometer of Brucker Company of Germany was used to scan the cement clinker of Examples 1-5 and Comparative Example 1, with the following test conditions: accelerating voltage of 40 kV, accelerating current of 40 mA, step size of 0.02, scanning time of 1 second for each step, and scanning angle of 10-70. After the end of the scanning, the software MAUD was used to refine the scanned results of the clinker samples using the Rietveld full-spectrum fitting analysis method, and the XRD patterns and refinement results were obtained to determine the mineral phase content. The results of the analyses of the contents of various mineral phases for different samples were shown in Table 1, and the XRD patterns were shown in FIG. 1.

##STR00001##

were the four main mineral phases of cement clinker, and the rest was a small amount of miscellaneous mineral phases. Under different calcination regimes, the crystal structure and mineral composition of cement clinker can change significantly. The sample numbers corresponding to Examples 1-5 and Comparative Example 1 were shown in Table 1, which were consistent with the sample numbers in the subsequent test examples.

TABLE-US-00001 TABLE 1 Content of main minerals in clinker (wt. %) Sample No. C.sub.3S C.sub.2S C.sub.3A C.sub.4AF Example 1 A1 61.9 13.5 2.5 21.9 Example 2 A2 64.7 12.4 2.7 20.1 Example 3 A3 69.1 11.4 2.0 17.4 Example 4 A4 63.3 14.2 2.0 20.4 Example 5 A5 66.9 11.1 2.3 19.4 Comparative A0 52.2 21.2 2.9 23.5 Example 1

[0059] As can be seen from Table 1, compared with sample A0 which was calcined in an air atmosphere in Comparative Example 1, the samples in Examples 1-5 which were calcined in an oxygen-rich atmosphere of mixed CO.sub.2/O.sub.2 have more significant increase in the content of C.sub.3S, but have more significant decrease in the content of C.sub.2S, C.sub.3A, and C.sub.4AF. The contents of C.sub.3S and C.sub.4AF changed significantly with the change of CO.sub.2 concentration. It can be seen that the calcination under the oxygen-rich atmosphere of mixed CO.sub.2/O.sub.2 of the present application can significantly increase the content of C.sub.3S in cement clinker.

[0060] In addition, when the CO.sub.2 content was relatively low, the content of C.sub.3S in the calcined samples increases gradually with the increase of the CO.sub.2/O.sub.2 ratio. In Example 3, the content of C.sub.3S in sample A3 which was calcined under the atmosphere environment with the CO.sub.2/O.sub.2 ratio reaching 0.59/0.41 reaches the highest (69.1%). Then the content of C.sub.3S begins to show a decreasing trend with the increase of the CO.sub.2/O.sub.2 ratio, and the content of C.sub.3S start to increase again when the CO.sub.2/O.sub.2 ratio reaches 0.79/0.21. Obviously, the effect of CO.sub.2/O.sub.2 atmosphere on the composition of the mineral phase in the calcined samples was relatively complex, which was most likely due to the changes in the temperature of the formation of the mineral phase and the liquid phase caused by the CO.sub.2/O.sub.2 atmosphere during the combustion process. In particular, the content and property of the liquid phase were crucial for the generation of C.sub.3S. The optimal calcining atmosphere was more favorable for the conversion of C.sub.2S to C.sub.3S, resulting in the highest content of C.sub.3S in the clinker. As can be seen from the above results, sample A3 of Example 3 has the highest C.sub.3S content (69.1%), which indicates that when the ratio of CO.sub.2/O.sub.2 is 0.59/0.41, it is the most favorable calcining atmosphere for the growth of C.sub.3S in clinker.

Test Example 2

[0061] A FC-6 Cement Free Calcium Oxide Rapid Tester was used to determine the free calcium oxide mass content of the cement clinker of Examples 1-5 and Comparative Example 1. The results were shown in FIG. 2.

[0062] The cement clinker of Examples 1-5 and Comparative Example 1 was crushed until all of the cement clinker passed through a 5 mm square-hole sieve, and then pulverized with natural gypsum dihydrate which meets the provisions of GB/T5483 in a standard test mill to form P.Math.I type portland cement, in which the mass content of natural gypsum dihydrate was 5%. The 3-day and 28-day compressive strength of P.Math.I type portland cement was measured according to GB/T 17671-2021 (Test Method of Cement Mortar Strength (ISO Method)), and the results were shown in FIG. 3.

[0063] As can be seen in FIG. 2, the free calcium oxide (f-CaO) content of the samples calcined in air atmosphere was 0.88 wt %, and the f-CaO content of all the samples calcined in CO.sub.2/O.sub.2 atmosphere decreased. This is because the addition of a certain concentration of CO.sub.2 to the atmosphere changed the equilibrium partial pressure of CO.sub.2 in the system and slowed down the decomposition process of carbonate salts. On the other hand, the f-CaO content in the clinker showed an obvious increasing trend as the ratio of CO.sub.2/O.sub.2 increased from 0.39/0.61 to 0.79/0.21. In addition, the f-CaO content of all experimental samples was always lower than 1.0 wt %, which met the f-CaO control requirements for clinker. The increase of free calcium oxide (f-CaO) content in cement clinker will directly affect the stability of cement, so it can be seen that the examples of the present application in which the calcining was performed under CO.sub.2/O.sub.2 atmosphere can ensure the stability of cement and improve the quality of cement.

[0064] As can be seen from FIG. 3, the compressive strength of samples A1 to A3 in the examples was increased, and then the compressive strength of samples A4 and A5 was decreased, indicating that a moderate increase in the ratio of CO.sub.2/O.sub.2 concentration was conducive to improving the compressive strength of cement, i.e., it can also reflect that the compressive strength of cement clinker were increased, and the compressive strength of cement clinker was the highest when the ratio of CO.sub.2/O.sub.2 reaches 0.59/0.41 (sample A3); when the ratio of CO.sub.2/O.sub.2 was further increased, the compressive strength started to decrease instead, but even with a ratio of CO.sub.2/O.sub.2 of 0.79/0.21, the compressive strength of the cement clinker was still comparable to that of sample A0 which was calcined under the conventional air atmosphere. That is, the cement clinker obtained by calcining under atmosphere of CO.sub.2/O.sub.2 with concentration ratios of 0.59/0.41, 0.69/0.31, and 0.79/0.21 in Examples 3-5 has high cement clinker compressive strength, and the quality of the cement clinker was further improved.

[0065] Moreover, it can be observed that sample A4 showed the highest strength growth rate (79.10%) in the age range of 3-28 days, and sample A3 also showed a relatively high strength growth rate (77.32%). Samples A0, A1 and A2 showed similar strength growth rates, which were all 75.10%, while sample A5 showed a relatively low strength growth rate. These results indicate that CO.sub.2-containing calcining atmosphere has an effect on the strength growth rate of clinker, and the highest strength growth rate of cement clinker was observed when ratios of CO.sub.2/O.sub.2 were 0.59/0.41 and 0.69/0.31.

[0066] In summary, it can be seen that the CO.sub.2 calcining atmosphere has an effect on the strength of clinker. When the CO.sub.2/O.sub.2 concentration ratio was in a range from 0.39/0.61 to 0.79/0.21, moderate increase in CO.sub.2/O.sub.2 concentration ratio was conducive to improving the compressive strength of cement clinker. When the ratio of CO.sub.2/O.sub.2 was 0.59/0.41 and 0.69/0.31, the strength of cement clinker was best, and the strength increase rate was greatest over the age range of 3-28 days.

Test Example 3

[0067] The cement clinker of Examples 1-5 and Comparative Example 1 was fixed with phenolic resin and then ground flat and polished, and the flat surface of the samples were corroded using ammonium chloride solution (wt %=1%), and the microstructural observations, measurements and analyses of the cement clinker of Examples 1-5 and Comparative Example 1 were subsequently carried out by using an Olympus BX-51 polarizing microscope. The polarizing microscope images obtained were shown in FIGS. 4 and 5, with two different positions selected for each sample. Observations were made under a polarizing microscope. At this time, the free calcium oxide will be colored, Alite (with the main ingredient of C.sub.3S) crystals were mainly blue or dark brown, with hexagonal or square shapes, and Belite (with the main ingredient of C.sub.2S) crystals were light brown with round shapes.

[0068] The sub-microstructures of clinker minerals obtained from different calcining atmospheres can be seen in FIGS. 4 and 5. Comparison of the mineral morphology of the six groups of samples under the reflected light microscope shows that when the calcining atmosphere was changed from air to CO.sub.2/O.sub.2, the number of Alite crystals in the clinker becomes larger, the size becomes larger, and the boundaries become clearer. With the change of the ratio of CO.sub.2/O.sub.2 in the calcining atmosphere, Alite crystals in clinker become larger in size and have clearer and more complete outlines, while Belite crystals become smaller in size and have blurrier outlines. Among all the samples, sample A3 shows the best crystal morphology. Most of the Alite crystals in sample A3 were relatively regular and complete in shape, mostly were hexagonal plates and short columns, with uniform size, more quantity (about 60%-70%), and more inclusions. Belite crystals were fewer in number, with moderate size, most of them were ellipsoidal and egg-shaped, with smooth edges, and a few of them have grain lines and crossbands. On the other hand, A0 sample of the comparative example has less Alite crystals, irregular shape, uneven size, blurred edges, and more adhesion among the minerals; Belite crystals can be seen in the field of view with higher content, basically rounded shape, smooth edges, and C.sub.3S scattered among them.

Test Example 4

[0069] The cement clinker of Examples 1-5 and Comparative Example 1 were hydrated for 3 days respectively, and the specific hydration steps included: in accordance with the water-cement ratio of 0.4:1, the cement clinker samples were made into 20 mm20 mm20 mm cement paste test blocks, and then demolded after 1 day of maintenance under the condition of standard constant temperature and constant humidity (temperature of 201 C., humidity of 951%), and further placed in deionized water at 201 C. for immersion for 2 days, then the test blocks were removed and cracked, and anhydrous ethanol was used to terminate hydration for subsequent testing and analysis. The hydrated samples of cement clinker of Examples 1-5 and Comparative Example 1 were characterized using field emission scanning electron microscopy (UltraPlus, Zeiss), to observe the size and morphology of crystals formed after the hydration of cement clinker, and the obtained scanning electron micrographs were shown in FIGS. 6 and 7, with two different positions selected for each sample.

[0070] FIGS. 6 and 7 show the surface microscopic morphology of clinker after hydration (for 3 days) obtained from different calcining atmospheres. From the images, it can be seen that the hydrated products on the surface of the samples with different calcining atmospheres were basically the same, i.e., the early product of hydration, type I hydrated calcium silicate (CSH), which was an elongated substance that grows radially outward from the cement particles. However, the distribution of hydrated products on the surface of A0 and A1 was more dispersed and the difference in mineral sizes was larger; sample A2 showed slat-like and tubular CSH; the mineral distribution of A3 and A4 was homogeneous and denser, and the cogwheel and fibrous CSH gels were distributed in staggered agglomerates, which were in the form of interlocking mesh, which suggested that the hydration degree of cement clinker in samples A3 and A4 was high, and that the hydration rate was fast, and also indirectly indicated that the compressive strength of the cements of A3 and A4 performed excellently under the CO.sub.2/O.sub.2 atmosphere ratios in Examples 3 and 4. The distribution of hydrated minerals on the surface of A5 was dispersed, with an increase in the number of inter-mineral grooves and cracks clearly visible, the minerals were small in size and basically completed hydration, and the elongated stripes of particles lap on spherical granular minerals which have already been hydrated, interspersed and distributed within them. On the other hand, sample A0 corresponding to Comparative Example 1 has a low degree of hydration, and there were still more hexagonal plates and short columns.

Test Example 5

[0071] The free calcium oxide content in cement clinker of Examples 6-14 was determined using FC-6 Cement Free Calcium Oxide Rapid Determiner. The test results were shown in Table 4.

[0072] The cement clinker of Examples 6-14 was scanned with a D8 Advance X-ray diffractometer from Brucker, Germany, under the following test conditions: accelerating voltage of 40 kV, accelerating current of 40 mA, step size of 0.02, scanning time of 1 second per step, and scanning angle of 10-70. At the end of the scanning, the clinker samples scanned results were refined using the software MAUD using the Rietveld full-spectrum fitting analysis method to determine the mineral phase content. The test results were shown in Table 4.

[0073] The cement clinker of Examples 6-14 was crushed until all of the cement clinker passed a 5 mm square-hole sieve, and then pulverized with natural gypsum dihydrate which meets the provisions of GB/T5483 in a standard test mill to form P.Math.I type portland cement, in which the mass content of natural gypsum dihydrate was 5%. The 3-day and 28-day compressive strength of P.Math.I type portland cement was measured according to GB/T 17671-2021 (Test Method of Cement Mortar Strength (ISO Method)), and the results were shown in FIG. 4.

[0074] Lithofacies scoring was carried out on the cement clinker obtained in Example 4 and Examples 6-14, and the lithofacies scoring was carried out by using Olympus BX-51 polarizing microscope to observe the microstructure of the clinker. The scores were determined on the basis of: the porosity, the size of the holes as well as their dimensions; the mineral content, the degree of erosion and the degree of uniformity of distribution; and the shapes and dimensions of crystals as well as their sizes, etc. The lithofacies scoring criteria were shown in Table 3, and the test results were shown in Table 4.

TABLE-US-00002 TABLE 3 Appearance Score (Total 9) Pore Small porosity, dense structure, without 3 obvious hole Smaller porosity, observed the existence 2 of holes, the diameter of the holes being basically less than 50 m Relatively large porosity, observed the 1 existence of more holes, the diameter of the holes being greater than 50 m but less than 100 m Large porosity, observed the existence 0 of many holes, the diameter of the holes being greater than 100 m Mineral High C.sub.3S content, uniform distribution, 3 content only sporadic f-CaO can be observed Relatively high C.sub.3S content, relatively 2 uniform distribution, scattered f-CaO can be observed Relatively low C.sub.3S content with 1 relatively uniform distribution, high C.sub.2S content with relatively uniform distribution, scattered f-CaO can be observed Low C.sub.3S content, high C.sub.2S content, 0 non-uniform distribution, a large number of agglomerated f-CaO can be observed Crystal Alite crystals are large in size, with 3 clear and complete outlines; Belite crystals are small in size, with blurred outlines Alite crystals are relatively large in 2 size, with clear and relatively complete outlines; Belite crystals are relatively small in size, with relatively blurred outlines Alite crystals are relatively small in 1 size, with relatively blurred outlines; Belite crystals are relatively small in size, with clear outlines Alite crystals are small in size, with 0 blurred outlines; Belite crystals are large in size, with clear outlines

TABLE-US-00003 TABLE 4 C.sub.3S content (wt %) f-CaO (wt %) Lithofacies scoring Example 4 60.4 0.66 8 Example 6 58.2 0.71 6 Example 7 59.3 0.77 5 Example 8 60.5 0.65 8 Example 9 60.3 0.71 6 Example 10 61.9 0.8 6 Example 11 61.8 0.57 5 Example 12 63.9 0.55 6 Example 13 61.4 0.54 7 Example 14 63.7 0.62 8 Comparative 52.2 0.88 4 Example1

[0075] Obviously, the above examples are merely examples for the purpose of clear illustration and are not a limitation of the embodiments. To those skilled ordinary in the art, other variations or changes in different forms may be made on the basis of the above description. It is neither necessary nor possible to exhaust all of the embodiments herein. The obvious variations or changes derived therefrom remain within the scope of protection of the present application.