JP2013224227A - Method for producing cement composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a cement composition having high strength development compared with blast furnace cement, etc., containing blast furnace slag, at a low production cost.SOLUTION: A method for producing a cement composition includes: (A) a clinker burning step to burn a cement clinker having a cement mineral composition of 20-80 mass% as CS, 5-60 mass% as CS, 1-16 mass% as CA and 6-16 mass% as CAF calculated by using a Bogue equation; (B) a slag processing step to charge 2-250 pts.mass of granulated blast furnace slag having a particle diameter of ≥1 mm based on 100 pts.mass of the clinker into a 710-1400°C region of a cooler, mixing it with the clinker, and cooling the clinker and at the same time heating and cooling the granulated blast furnace slag to obtain a mixture of clinker and processed granulated blast furnace slag; and (C) a crushing step to crush the mixture or crush a mixture obtained by adding gypsum to the mixture.

Description

  INDUSTRIAL APPLICABILITY The present invention includes a cement composition that has higher strength development than conventional blast furnace cement and the like, including blast furnace granulated slag (hereinafter referred to as “blast furnace slag”), and can contain a large amount of processed blast furnace slag. It relates to the manufacturing method.

Blast furnace cement has properties such as long-term strength development, durability, waterproofness, and high wear resistance, and low hydration heat generation compared to ordinary Portland cement (hereinafter referred to as “ordinary cement”). There is an advantage that CO ₂ and raw material limestone can be greatly reduced in cement production. These reduction rates are, for example, as high as about 40% in the blast furnace cement type B compared to ordinary cement. Therefore, blast furnace cement is extremely useful as a means for reducing CO ₂ emissions and saving natural resources in cement production.
Moreover, according to the statistics of the Steel Slag Association, the production of blast furnace slag in FY2010 was 1.84 million tons, of which the amount of blast furnace slag used for cement was 15.51 million tons, 78% of the total. In particular, there is sufficient room for expanding the use.

However, blast furnace cement is inferior in initial strength development before the age of 28 days and is not suitable for structures requiring initial strength such as girders, floor slabs, and building frames. The reason for this poor initial strength is that blast furnace slag has a property (latent hydraulic) that gradually hydrates due to the stimulation of calcium hydroxide caused by hydration of the clinker, so compared to hydraulic cement clinker. The point where hydration progresses slowly is mentioned. In fact, as shown in FIG. 2 on page 93 of Non-Patent Document 1, JIS mortar (before the 1997 revision) using a composition in which ordinary cement is gradually replaced with blast furnace slag has a compression strength of 3 days. As the added amount of blast furnace slag increases, it decreases significantly. When the added amount of blast furnace slag is 70%, it is only about 30 to 35% of the strength of the plain (see FIG. 1 of this drawing).
Therefore, if the latent hydraulic property of blast furnace slag can be improved, it is expected that blast furnace cement can be used for applications that require initial strength.

In response to the expectation, a method for increasing the latent hydraulic property of the blast furnace slag has been proposed.
For example, Patent Document 1 proposes a blast furnace water tank in which a blast furnace water tank is rapidly heat-treated at 400 to 700 ° C. for 5 to 30 minutes and rapidly cooled to 100 ° C. or less and a low heat generating cement including the blast furnace water tank. However, in this method, the rapid heat treatment and the rapid cooling treatment of the blast furnace water tank are performed separately, so that the loss of heat energy is large and the energy efficiency is low. Moreover, as described in the examples, the blast furnace water tank was pulverized alone to obtain a pulverized product having a brane value of 4500 cm ² / g. The brane value was a blast furnace slag used for blast furnace cement type B. Is higher than the brane value (about 4100 cm ² / g), the grinding cost is increased. Furthermore, from the viewpoint of pulverization cost, mixed pulverization in which both are mixed and pulverized at the same time is superior to the separate pulverization in which the blast furnace water tank and cement clinker are separately separated and pulverized in the low heat generation cement.
Therefore, there is a demand for a method for producing a cement composition that has higher strength than conventional blast furnace cement containing blast furnace slag, and that can contain a large amount of processed blast furnace slag and has low production costs. Yes.

Akihiko Yoda et al. “Strength of mortar and concrete using pulverized blast furnace slag as an admixture”, Cement Technology Annual Report, Vol.42, pp.92-95, 1988

Japanese Patent Publication No. 07-106929

  Therefore, the present invention provides a method for producing a cement composition that has higher strength than conventional blast furnace cement containing blast furnace slag, can contain a large amount of treated blast furnace slag, and has low production costs. The purpose is to provide.

Therefore, the present inventors have examined a method for producing a cement composition that meets the above-mentioned purpose,
(I) When a blast furnace slag having a specific particle size is introduced into and mixed with a clinker having a specific cement mineral composition in a specific temperature range of the cooler, heat exchange between the clinker and the blast furnace slag is performed in the mixing process. The clinker has a higher cooling rate than if it is simply cooled by a cooler, and at the same time, the blast furnace slag is heated and cooled to obtain a mixture of clinker with improved hydraulic properties and blast furnace slag with improved latent hydraulic properties,
(Ii) By simply mixing and grinding the mixture, a cement composition having a high initial strength can be easily produced;
(Iii) According to this production method, it was found that a large amount of blast furnace slag can be used, and that the energy efficiency and grinding efficiency are high and the production cost can be reduced, thereby completing the present invention.

That is, the present invention provides the following [1] to [3]. “%” Is “% by mass” unless otherwise specified.
[1] A method for producing a cement composition including the following steps (A) to (C).
Cement mineral composition calculated using (A) Borg formula, 20-80% by _{C 3} S, 5 to 60% for _{C 2} S, 1 to 16% in the _{C 3} A, and at _C 4 AF 6 to 16 The clinker firing step (B) for firing the cement clinker that is 100% by mass of blast furnace slag having a particle diameter of 1 mm or more in a ratio of 2 to 250 parts by mass with respect to 100 parts by mass of the clinker. The slag treatment step of mixing the clinker with the clinker and simultaneously heating and cooling the blast furnace slag to obtain a mixture of the clinker and a treated product of the blast furnace slag (hereinafter referred to as “slag treated product”). (C) A pulverization step of pulverizing the mixture or pulverizing a mixture obtained by adding gypsum to the mixture

[2] The amount of gypsum added in the step (C) is 0.5 to 4.0 parts by mass in terms of SO ₃ with respect to 100 parts by mass of the mixture of the clinker and the slag-treated product. The manufacturing method of the cement composition as described in any one of.
[3] The method for producing a cement composition according to [1] or [2], wherein the slag-treated product after cooling has a vitrification rate of 85% or less.

  According to the method for producing a cement composition of the present invention, strength development is higher than conventional blast furnace cement containing untreated blast furnace slag, and a large amount of treated blast furnace slag can be included. A cement composition having a low production cost can be provided.

It is a figure which shows the compressive strength of the mortar by JISR5201 published on page 93 of the nonpatent literature 1. It is a schematic diagram which shows one example of the manufacturing apparatus for enforcing the manufacturing method of this invention.

1. Clinker manufacturing process As described above, the clinker manufacturing method of the present invention includes (A) a clinker baking process, (B) a slag treatment process, and (C) a pulverization process as an essential process, and further, as an optional process (D) The raw material preparation process is included.
Hereinafter, the present invention will be described separately for each step.

(A) clinker burning step the process, cement mineral composition calculated using the Borg type, 20-80% by _{C 3} S, 5 to 60% for _{C 2} S, 1 to 16% in the _{C 3} A, and , which is then burned cement clinker is 6-16% in the _C 4 AF. Examples of the clinker having a cement mineral composition within this range include ordinary Portland cement clinker, Portland cement clinker such as early-strength Portland cement clinker, and eco-cement clinker.
1000-1450 degreeC is preferable and the baking temperature of this process has more preferable 1200-1400 degreeC. When the temperature is in the range of 1000 to 1450 ° C., cement minerals having high hydraulic properties tend to be generated. Moreover, 30-120 minutes are preferable and, as for the baking time of this process, 40-60 minutes are more preferable. When the time is less than 30 minutes, firing is not sufficient, and when it exceeds 120 minutes, productivity is lowered.

In addition, when waste is used as part of the cement raw material in the production method of the present invention, heavy metals may be mixed in the clinker. When the heavy metal content in the clinker exceeds the specified value, the heavy metal content can be adjusted within the specified value range using a chlorination volatilization method or a reduction baking method in the clinker baking step.
Here, the chlorination volatilization method is a method in which heavy metals contained in the cement raw material are volatilized and removed in the form of chlorides having a low boiling point. Specifically, in this method, a chlorine source such as calcium chloride is added to a cement raw material containing heavy metal, and is fired using a firing furnace such as a rotary kiln, and the generated heavy metal chloride is volatilized and removed. It is.
The reduction firing method is a method in which heavy metals contained in a cement raw material are reduced and volatilized and removed in the form of a metal having a low boiling point. Specifically, in this method, a cement raw material containing heavy metal is reduced in a reducing atmosphere and / or added with a reducing agent, and baked using a baking kiln such as a rotary kiln to reduce heavy metal and reduce this. Heavy metals are volatilized and removed.

The content (composition) of the C ₃ S, C ₂ S, C ₃ A, and C ₄ AF is calculated using the following Borg formulas (i) to (iv).
C ₃ S (%) = 4.07 × CaO (%) − 7.60 × SiO ₂ (%) − 6.72 × Al ₂ O ₃ (%) − 1.43 × Fe ₂ O ₃ (%) − 2.85 × SO ₃ (%) (i)
C ₂ S (%) = 2.87 × SiO ₂ (%) − 0.754 × C ₃ S (%) (ii)
C ₃ A (%) = 2.65 × Al ₂ O ₃ (%) − 1.69 × Fe ₂ O ₃ (%) (iii)
C ₄ AF (%) = 3.04 × Fe ₂ O ₃ (%) (iv)
(The chemical formula in the formula represents the content of the compound represented by the chemical formula in the preparation raw material or in the clinker.)

(B) Slag treatment step This step is performed by adding blast furnace slag having a particle diameter of 1 mm or more to a 710 to 1400 ° C region in a cooler at a ratio of 2 to 250 parts by mass with respect to 100 parts by mass of the clinker. The mixture is mixed and the clinker is cooled, and at the same time, the blast furnace slag is heated and cooled to obtain a mixture of the clinker and the processed slag. In this step, the clinker has a higher cooling rate than when it is simply cooled by a cooler, resulting in improved hydraulic properties. Moreover, as a result of heating and cooling the blast furnace slag, the latent hydraulic property is improved.
If the input amount (use amount) of the blast furnace slag is less than 2 parts by mass, the use amount of the blast furnace slag is small, and it becomes difficult to increase the cooling rate of the clinker, and the effect of improving the strength expression of the clinker itself is reduced. If the value exceeds 250 parts by mass, the strength development of the cement composition may be reduced. The lower limit of the value is preferably 5 parts by mass with respect to 100 parts by mass of the clinker, and more preferably 10 parts by mass. The upper limit of the value is preferably 200 parts by mass with respect to 100 parts by mass of the clinker, and 150 parts by mass. Is more preferable.

The particle size of the blast furnace slag is 1 mm or more. If the particle size is less than 1 mm, the clinker and blast furnace slag are likely to react, and the (initial) strength development of the clinker may be reduced. The particle size of the blast furnace slag is preferably 2 mm or more, and more preferably 3 mm or more from the viewpoint of strength development of the cement composition. In addition, the particle size of blast furnace slag is 150 mm or less because it is difficult to obtain a blast furnace slag having a particle diameter of more than 150 mm, it takes time to put into a cooler, and the pulverization efficiency is lowered. It is preferable that
The temperature of the region in the cooler where the blast furnace slag is charged is 710 to 1400 ° C. If the temperature is lower than 710 ° C, the strength development of the cement composition may be reduced. If the temperature is higher than 1400 ° C, the clinker and blast furnace slag are likely to react, and the (initial) strength development of the clinker may be reduced. . In addition, this temperature has preferable 750-1350 degreeC, and 800-1300 degreeC is more preferable.

The vitrification rate of the slag-treated product after cooling is preferably 85% or less, more preferably 80% or less, and further preferably 75% or less. If the vitrification rate exceeds 85%, as shown in Comparative Examples 1 and 2 in Table 1 below, the strength development of the cement composition tends to be reduced.
Conventionally, the vitrification rate is widely used as an evaluation index for quality control of blast furnace slag, and it is a well-known fact that the latent hydraulic property of blast furnace slag is low when the vitrification rate is low. However, in the present invention, even if the vitrification rate of the slag-treated product is low, the phenomenon that the strength development of the cement composition containing the treated product is improved is contrary to the conventional experience fact, and even a person skilled in the art can expect it. It is something that cannot be done. Incidentally, crystal products such as C ₂ S and a small amount of gehlenite have been confirmed in the treated product.
The vitrification rate is usually expressed by the ratio of the number of points of the vitrified portion to the total number of points by counting points of the crystallized portion and vitrified portion in the thermally denatured product using a polarizing microscope.

(C) Grinding step This step is to obtain a cement composition by pulverizing the mixture of the clinker and slag-treated product after passing through the cooler, or pulverizing the mixture obtained by adding gypsum to the mixture. is there. The mixture to which gypsum is added is preferably pulverized because the pulverization is only once.
However, if the mixture of the clinker and the slag-treated product is significantly different from the pulverization property of the gypsum, the mixture and the gypsum are separately pulverized separately in order to suppress excessive expansion of the particle size distribution. May be. In this case, the Blaine specific surface area of the gypsum is preferably ^{2000~5000cm 2 / g, 3000~4000cm 2 /} g is more preferable. When the value is out of the range of 2000 to 5000 cm ² / g, there is a possibility that strength development property is lowered or heat of hydration is increased.

The amount of gypsum added is preferably 0.5 to 4.0 parts by mass, more preferably 1.0 to 3.5 parts by mass in terms of SO ₃ with respect to 100 parts by mass of the mixture of the clinker and slag processed product. 5-3.0 mass parts is more preferable. When the value is in the range of 0.5 to 4.0 parts by mass, the cement composition has high strength and good fluidity.
The type of gypsum is not particularly limited, and for example, at least one selected from natural dihydrate gypsum, flue gas desulfurization gypsum, phosphate gypsum, titanium gypsum, hydrofluoric gypsum, smelted gypsum, hemihydrate gypsum, anhydrous gypsum, and the like. More than species.

  In the pulverization, the mixture of the clinker and the slag-treated product may be pulverized as it is, but is preferably pulverized by adding a pulverization aid in order to increase the pulverization efficiency. Examples of the grinding aid include diethylene glycol, triethanolamine, and triisopropanolamine. Among these, triisopropanolamine is more preferable because strength development of the cement composition is improved. The addition ratio of these grinding aids is preferably 0.01 to 1 part by mass with respect to 100 parts by mass of the mixture. As the pulverizer, a ball mill, a rod mill, or the like can be used.

Fineness of the cement compositions produced according to the present invention, strength development, workability, and in view of manufacturing cost, it is preferable 2000~5000cm ² / g in Blaine specific surface area, 2500~4700cm ² / g Gayori Preferably, 3000 to 4000 cm ² / g is more preferable.
The cement composition may further contain fly ash, coal ash, silica fume, silica powder, limestone powder, and the like as long as the physical properties of the cement composition are not impaired.
The manufacturing method of the present invention including the above steps can use a large amount of blast furnace slag, and can reduce manufacturing costs. In addition, as shown in Table 2 below, the cement composition produced according to the present invention has improved initial and long-term strength development and can be used for applications that require initial strength.

(D) Raw material preparation process Furthermore, the manufacturing method of this invention can include the raw material preparation process for preparing a cement raw material before the said (A) process as arbitrary processes.
In this step, a cement raw material such as a calcium raw material, a silicon raw material, an aluminum raw material, and an iron raw material is prepared so as to be included in the range of the cement mineral composition by using the Borg formulas of the formulas (i) to (iv). Prepare the ingredients. Here, limestone, quicklime, slaked lime, and the like are used as the calcium material, silica and clay are used as the silicon material, clay is used as the aluminum material, and iron cake and iron cake are used as the iron material.
In addition, since the chemical composition of the compounded raw material before firing is almost the same as the chemical composition of the clinker after firing, in order to obtain a clinker having the cement mineral composition, it is usually calculated based on the Borg equation. It is sufficient to prepare raw materials that satisfy the mineral composition. However, for the sake of accuracy, a part of the raw material is fired in an electric furnace or the like, and the correlation between the raw material and the mineral composition in the clinker obtained by firing is known in advance. It is preferable to correct the mixing ratio of the raw materials so that the mineral composition in the target clinker is obtained.

As the raw material, in addition to natural raw materials, industrial waste, general waste, and / or waste such as construction generated soil can be used as part of the raw material.
Examples of the industrial waste include various sludges such as coal ash, ready-mixed concrete sludge, construction sludge, iron sludge, boring waste soil, various incineration ash, foundry sand, rock wool, blast furnace secondary ash, construction waste, and concrete waste Etc.
Examples of the general waste include purified water sludge, sewage sludge, sewage sludge dry powder, municipal waste incineration ash, shells, and sewage sludge incineration ash.
Examples of the construction generated soil include soil and residual soil generated from a construction site and a construction site.
In addition, when it is necessary to adjust the fineness of a preparation raw material, it grind | pulverizes and adjusts to a predetermined fineness with raw material grinders, such as a ball mill.

Hereinafter, although an example and a drawing explain the present invention, the present invention is not limited to these examples and drawings.
1. Production of Cement Composition A normal cement clinker (hereinafter referred to as “clinker”) having 59% C ₃ S, 16% C ₂ S, 9% C ₃ A, and 9% C ₄ AF is referred to as rotary kiln 1. Was fired at 1400 ° C. and dropped onto the cooler 3.
Next, blast furnace slag having a particle size in the range of 1 to 106 mm and a vitrification rate of 99% was charged at the temperature position shown in Table 1 of the cooler at the charging rate shown in Table 1. The blast furnace slag and the clinker were mixed while moving in the cooler 3 to obtain a mixture of the clinker and the slag processed product cooled at the outlet of the cooler 3. The particle size composition of the blast furnace slag used was 45% when the particle size is 1 to 9.5 mm, 35% when it exceeds 9.5 mm and 53 mm or less, and 20% when it exceeds 53 mm and 106 mm or less. .
Next, a part of the mixture was mixed and pulverized as it was to obtain a mixed pulverized powder (Pm ₁ ). On the other hand, after the clinker and the slag-treated product are visually separated based on the color difference between the clinker and the slag-treated product, the clinker powder (Pc) and the slag-treated product powder ( Ph) was obtained, and both powders were further mixed to obtain separated pulverized powder (Ps).
Further, the blast furnace slag was mixed with the clinker as it was without being put into a cooler and pulverized to obtain a mixed pulverized powder (Pm ₂ ).

Thereafter, dihydrate gypsum (reagent 1) in terms of SO _{3 with} respect to 100 parts by mass of each of the mixed pulverized powder (Pm ₁ ), the separated pulverized powder (Ps), the mixed pulverized powder (Pm ₂ ), and the clinker powder (Pc). Grade 1.3; manufactured by Kanto Chemical Co., Ltd.) and 1.3 parts by mass of hemihydrate gypsum (reagent grade 1, manufactured by Kanto Chemical Co., Ltd.), and then pulverized again with a small mill, respectively. Cm ₁ (Examples 1 to 3, Comparative Example 2), cement composition Cs (Comparative Example 1, Reference Examples 1 and 2), cement composition Cm ₂ (Comparative Examples 3 and 4), and ordinary cement Cn (Reference Example) 3, 4) was produced. Further, as Reference Example 5, commercially available ordinary cement (manufactured by Taiheiyo Cement Co., Ltd.), as Reference Example 6, a commercially available blast furnace cement type B (manufactured by Taiheiyo Cement Co., Ltd., blast furnace slag content 40%, Blaine specific surface area 3850 cm ² / g). Using.
Table shows the cooler temperature, the slag charge ratio (in the case of Comparative Examples 3, 4 and Reference Example 6, “mixing ratio”), the pulverization method of the mixture, the Blaine specific surface area of the cement composition, and the vitrification ratio of the slag-treated product It is shown in 1.

2. Measurement of compressive strength of mortar According to JIS R 5201 “Physical testing method of cement”, a mortar was prepared using the cement composition and cement, and the compressive strength of the mortar from 3 days to 91 days was measured. .
Table 1 shows the measurement results of the compressive strength of the mortar, and Table 2 shows the ratio of these compressive strengths.

3. About the meaning of an Example, a comparative example, and a reference example The significance of the Example etc. in Table 1 is described below.
(I) Examples 1-3 are the manufacture examples by the method of Claim 1.
(Ii) In Comparative Examples 1 and 2, the cooler temperature at the position where the blast furnace slag was charged is as low as 600 ° C., which corresponds to the production example of the low heat generation cement described in Patent Document 1.
(Iii) Comparative examples 3 and 4 are examples in which the blast furnace slag is mixed with the pulverized clinker as it is, and corresponds to a production example of ordinary blast furnace cement and the like.
(Iv) Reference examples 1 and 2 are production examples of a cement composition in which a separated and pulverized clinker and a slag-treated product are mixed, and are for comparison with a cement composition comprising a mixed and crushed clinker and a slag-treated product.
(V) Reference examples 3 and 4 are examples in which gypsum is mixed with the separated and pulverized clinker, and correspond to examples of production of ordinary ordinary cement.
(Vi) Reference Example 5 is an example using a commercially available ordinary cement, and Reference Example 6 is an example using a commercially available blast furnace cement type B.

4). About compressive strength, such as an Example From Table 1 and Table 2, the following can be said about compressive strength.
(1) Example 1 is about 10% higher at all ages compared to Comparative Example 3, and Example 2 is about 16-20% higher at all ages than Comparative Example 4. Further, Example 3 is higher than Comparative Example 4 by about 20% at the maximum in all ages, although the amount of blast furnace slag used is large. Furthermore, even if Example 2 and 3 are compared with the reference example 6, although the usage-amount of blast furnace slag is large and the brane specific surface area of a cement composition is small, it is equivalent or more. Therefore, the cement composition according to the present invention is more excellent in initial and long-term strength development than conventional blast furnace cement containing untreated blast furnace slag.
(2) Example 1 is almost the same as Reference Example 1, and Example 2 is almost the same as Reference Example 2. Accordingly, the influence of the mixed pulverization in the present invention on the strength development is equivalent to that of the separation pulverization. Therefore, since the mixed pulverization usually has higher pulverization efficiency than the separation pulverization, the production method of the present invention has an advantage that the pulverization cost is low.
(3) Example 1 is equal to or greater than Reference Example 5. Therefore, the initial strength development of the cement composition of Example 1 is improved to be equal to or higher than that of ordinary cement.
(4) Example 2 is about 10 to 20% higher than Comparative Examples 1 and 2. Therefore, the cement composition of Example 2 has higher strength development than the low heat-generating cement described in Patent Document 1 even though the cement composition contains 50% of the slag-treated product.
(5) Reference examples 3 and 4 are about 3 to 10% higher than reference example 5.
As described above, the reason why the initial strength development property of the cement composition according to the production method of the present invention is improved is that the hydraulic property of the clinker itself is improved and the latent hydraulic property of the slag-treated product is also improved. The
Therefore, the method for producing a cement composition of the present invention can provide a cement composition having higher strength development and lower production cost than conventional blast furnace cement using untreated blast furnace slag.

1 Rotary kiln 2 Preheater 3 Cooler 4 Front of kiln 5 Main burner 6 Clinker

Claims (3)

The manufacturing method of the cement composition including the following (A)-(C) processes.
(A) The cement mineral composition calculated using the Borg formula is 20 to 80% by mass for C ₃ S, 5 to 60% by mass for C ₂ S, 1 to 16% by mass for C ₃ A, and C ₄ AF. Clinker firing step for firing cement clinker having a mass of 6 to 16% (B) With respect to 100 parts by mass of the clinker, a granulated blast furnace slag having a particle size of 1 mm or more in a proportion of 2 to 250 parts by mass in the cooler A slag treatment process in which a mixture of clinker and granulated blast furnace slag is obtained by charging the 710 to 1400 ° C. region and mixing with the clinker, cooling the clinker and simultaneously heating and cooling the blast furnace granulated slag. (C) A pulverization step of pulverizing the mixture or pulverizing a mixture obtained by further adding gypsum to the mixture The addition amount of gypsum in the step (C) is 0.5 to 4.0 parts by mass in terms of SO ₃ with respect to 100 parts by mass of the mixture of the clinker and the processed product of the granulated blast furnace slag. 2. A method for producing a cement composition according to 1.   The manufacturing method of the cement composition of Claim 1 or 2 whose vitrification rate of the processed material of the said granulated blast furnace slag after cooling is 85% or less.

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