γ-2CaO∙SiO2-INCLUDING FIRED PRODUCT AND MANUFACTURING METHOD THEREFOR
A calcined product with optimized composition and particle size distribution accelerates carbonation in concrete, addressing inefficiencies in existing methods by enhancing carbonation in low CO₂ environments and improving durability.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- TOKUYAMA CORP
- Filing Date
- 2025-10-06
- Publication Date
- 2026-06-04
AI Technical Summary
Existing methods for promoting the carbonation of γ-2CaO·SiO₂ in concrete require high carbon dioxide concentrations and specialized equipment, making them inefficient for large-scale applications.
A calcined product with a specific composition and particle size distribution is developed, characterized by a high Blaine specific surface area and controlled content of certain minerals, which enhances carbonation even in low CO₂ environments.
The calcined product accelerates carbonation in concrete, reducing the curing time and increasing durability, while being suitable for large-scale applications without specialized equipment.
Smart Images
Figure JP2025035390_04062026_PF_FP_ABST
Abstract
Description
γ-2CaO・SiO2-containing calcined product and method for producing the same
[0001] This invention relates to γ-2CaO・SiO ２ The present invention relates to a calcined product containing the same and a method for producing the same.
[0002] In recent years, the global trend towards decarbonization has been accelerating, and this movement is also becoming more active in the cement industry, a typical high-consumption industry. In this context, 2CaO·SiO, which does not have hydraulic properties but has high carbonation activity, is being considered. ２ The γ-type has attracted attention in recent years, and many studies are being conducted on its potential uses. For example, γ-2CaO・SiO ２ It is known that by forcibly curing concrete mixed with an admixture through carbonation, a highly durable concrete with a denser surface layer can be obtained, and its usefulness has been discovered in recent years (Patent Document 1).
[0003] Japanese Patent Publication No. 2006-182583
[0004] The above γ-2CaO·SiO ２ Carbonation curing is usually carried out by absorbing carbon dioxide from the atmosphere, but since the concentration of carbon dioxide in the atmosphere is not sufficiently high, there is a problem that carbonation takes a long time. To solve this problem, a method has been proposed in which carbonation proceeds in a short time in a curing tank supplied with high concentration carbon dioxide. However, this method also has problems such as requiring special equipment and being difficult to apply to large concrete products.
[0005] The object of the present invention is to shorten the carbonation curing period of γ-2CaO・SiO ２ The objective is to provide a calcined product containing the same, and a method for producing the same.
[0006] As described above, the inventors used a special apparatus to produce γ-2CaO·SiO ２ Rather than promoting the carbonation of γ-2CaO·SiO ２ In our diligent research to change the properties of the substance itself and promote carbonation, we have discovered γ-2CaO・SiO ２Focusing on the granulation phenomenon and finding conditions that can make its particle size smaller, the present invention has been completed. That is, the γ-2CaO·SiO with a small particle size ２ The calcined product containing it has a large specific surface area, so the contact area with carbon dioxide increases, and carbonation can be promoted.
[0007] That is, the present invention is as follows. [1] γ-2CaO·SiO characterized in that the content of 4CaO·Al ２ O ３ ·Fe ２ O ３ is 6.0 to 65.0% by mass. ２ Calcined product containing.
[0008] [2] The γ-2CaO·SiO according to [1] above, characterized in that the Blaine specific surface area is 2000 cm ２ / g or more. [3] The γ-2CaO·SiO according to [1] or [2] above, characterized in that the content of γ-2CaO·SiO ２ is 20.0% by mass or more. [4] The γ-2CaO·SiO according to any one of [1] to [3] above, characterized in that the content of 2CaO·Al ２ O ２ ·SiO ２ O ３ ·SiO ２ is 3.0% by mass or less. ２ Calcined product containing.
[0009] [5] A method for producing the γ-2CaO·SiO according to any one of [1] to [4] above, comprising using, as a raw material, a raw material mixture containing a CaO raw material and a SiO ２ raw material, and having a total content of Al ２ O ２ and Fe ３ O ２ and Fe ３ of 35.0% by mass or less after heating at 1000°C. [6] The raw material mixture has a content of Fe ２ after heating at 1000°C, in terms of mass, and the content of Fe ２ O ３ is the content of Al ２ O ３The γ-2CaO・SiO2 described in [5] above is characterized by being a raw material mixture in a quantity greater than the content. ２ Method for producing a calcined product containing [7] The γ-2CaO・SiO2 described in [5] or [6] above, characterized by calcining the raw material mixture at 1300 to 1600°C. ２ Method for producing calcined products containing the active ingredient.
[0010] According to the present invention, the carbonation curing period can be shortened for γ-2CaO・SiO ２ We can provide calcined products containing the active ingredients and methods for producing them.
[0011] Manufactured γ-2CaO·SiO ２ This figure shows the particle size distribution of the calcined products containing the material (Comparative Example 1, Comparative Example 2, Example 2, and Comparative Example 4).
[0012] The present invention γ-2CaO・SiO ２ The calcined product it contains is 4CaO・Al ２ O ３ Fe ２ O ３ It is characterized by having a content of 6 to 65% by mass.
[0013] The present invention γ-2CaO・SiO ２ The calcined product it contains is 4CaO・Al ２ O ３ Fe ２ O ３ Since the content of is within the above range, the particle size is small in the unground state (see Figure 1). That is, the γ-2CaO・SiO of the present invention ２ The calcined material containing the active ingredient has a large specific surface area (Blaine specific surface area), which increases the contact area with carbon dioxide, thus promoting carbonation. Therefore, even in an atmosphere with a low carbon dioxide concentration, carbonation proceeds more rapidly than with conventional methods, shortening the curing period. Although the particle size of the calcined material can be adjusted by grinding, this requires grinding energy, so the calcined material of the present invention, which has a small particle size without grinding, is extremely useful.
[0014] The present invention γ-2CaO・SiO ２ 4CaO·Al in the calcined product containing it ２ O ３ Fe ２ O３ The content is 6.0 to 65.0% by mass as described above, but it is preferably 6.0 to 30.0% by mass, more preferably 6.0 to 25.0% by mass, even more preferably 8.0 to 20.0% by mass, and still more preferably 15.0 to 20.0% by mass, in order to increase the Blaine specific surface area.
[0015] Furthermore, the γ-2CaO・SiO of the present invention ２ For example, the Blaine specific surface area of the calcined product containing the active ingredient is 2000 cm². ２ It is preferable that it be 2500 cm or more per gram. ２ It is more preferable that it be 3000 cm or more per gram. ２ It is even more preferable that it be 3500 cm or more per gram. ２ It is particularly preferable that the amount be 4000 cm or more. ２ It is most preferable that the value be 1 / g or more.
[0016] Furthermore, the γ-2CaO・SiO of the present invention ２ Median diameter D of the calcined product containing the active ingredient ５０ (By volume) it is preferably 15.0 μm or less, more preferably 13.0 μm or less, even more preferably 12.0 μm or less, particularly preferably 10.0 μm or less, and most preferably 8.0 μm or less.
[0017] Furthermore, the γ-2CaO・SiO of the present invention ２ 2CaO・Al in the calcined product ２ O ３ SiO ２ The content is 2CaO・Al ２ O ３ SiO ２ However, it has poor hydraulic properties and carbonation reactivity, and does not exhibit strength development or CO2 ２ From the viewpoint of fixing ability, it is preferable that the amount is 3.0% by mass or less. 2CaO・Al ２ O ３ SiO ２ The content of is more preferably 2.0% by mass or less, and even more preferably 1.0% by mass or less.
[0018] The present invention γ-2CaO・SiO２ γ-2CaO·SiO containing the fired product ２ The content thereof is preferably as large as possible. For example, it is preferably 20% by mass or more, more preferably 30% by mass or more, still more preferably 40% by mass or more, and particularly preferably 50% by mass or more. Further, it is preferable that the content of γ-2CaO·SiO ２ is larger than that of β-2CaO·SiO ２
[0019] The γ-2CaO·SiO ２ containing fired product of the present invention can be used, for example, as a cement admixture. Concrete or mortar using cement containing this fired product is carbonated during its production, so that the surface layer part is rapidly densified and has high durability. Further, in the production of such concrete, etc., since carbon dioxide is absorbed during carbonation curing, it is also possible to reduce the carbon dioxide emission amount in obtaining concrete products.
[0020] As the raw material for obtaining the γ-2CaO·SiO ２ containing fired product of the present invention as described above, a raw material mixture containing a CaO raw material and a SiO ２ raw material and having a total content of Al ２ O ３ and Fe ２ O ３ of 35.0% by mass or less after heating at 1000°C is preferably used. Thereby, the particle size of the γ-2CaO·SiO ２ containing fired product can be reduced and the Blaine specific surface area can be increased. The total content of Al ２ O ３ and Fe ２ O ３ is more preferably 3.0 to 18.0% by mass, still more preferably 4.0 to 15.0% by mass, particularly preferably 5.0 to 12.0% by mass, and most preferably 9.0 to 11.5% by mass.
[0021] Further, Al ２ O ３ and Fe ２ O３ The content of ２ O ３ in terms of mass, from the viewpoint of reducing the firing temperature, the content of Fe ２ O ３ is preferably more than the content of Al ２ O ３ For example, the content of Fe ２ O ３ is preferably 1.1 to 2.0 times, more preferably 1.3 to 1.8 times, that of the content of Al
[0022] That is, the raw materials for obtaining the γ-2CaO·SiO ２ containing fired product of the present invention are CaO raw material, SiO ２ raw material, Al ２ O ３ raw material and Fe ２ O ３ raw material are used.
[0023] As the CaO raw material and SiO ２ raw material, the CaO raw material and SiO ２ raw material known as raw materials for cement clinker production can be used without limitation. Specifically, CaO raw materials such as limestone, quicklime, and slaked lime, and SiO ２ raw materials such as silica stone and silica fume can be mentioned. As the Al ２ O ３ raw material and / or Fe ２ O ３ raw material, from the viewpoint of effectively utilizing waste, it is preferable to use waste containing Al ２ O ３ and / or Fe ２ O ３
[0024] As the Al ２ O ３ raw material and / or Fe ２ O ３Waste containing Al includes waste and by-products used in cement manufacturing, etc. While usable waste is not particularly limited, specific examples include blast furnace slag such as granulated blast furnace slag and slow-cooled blast furnace slag, converter slag, electric furnace slag, steelmaking slag, non-ferrous slag, coal ash, concrete sludge (including returned concrete and leftover concrete), waste concrete, sewage sludge, water treatment sludge, papermaking sludge, construction waste soil, foundry sand, fly ash, incinerator fly ash, molten fly ash, chlorine bypass dust, wood chips, waste clay, spoil, waste tires, seashells, municipal solid waste and its incineration ash, etc. (Note that some of these can also be used as a source of thermal energy). Among these, Al is used in the manufacture of cement clinker. ２ O ３ The amount of Al used is limited by its quantity. ２ O ３ Waste containing Al is preferable because it further promotes the effective utilization of waste. ２ O ３ Typical waste materials containing Al include blast furnace slag, converter slag, electric furnace slag, steelmaking slag, non-ferrous metal slag, coal ash, concrete sludge, waste concrete, sewage sludge, water treatment sludge, papermaking sludge, foundry sand, incinerator fly ash, molten fly ash, municipal solid waste and its incinerator ash, etc. Among these, Al is more abundant compared to the composition of ordinary cement clinker. ２ O ３ It has a high content, and its main components are CaO and SiO ２ Al ２ O ３ From this perspective, the use of coal ash, blast furnace slag, converter slag, electric furnace slag, concrete sludge, waste concrete, incinerator fly ash, and municipal solid waste incineration ash is preferable. Furthermore, Fe ２ O ３ Because they contain a large amount of aluminum, converter slag and electric furnace slag are particularly preferable to use. These waste materials may also be used in combination. If the aluminum and iron content in the raw materials is low, Al may be added separately. ２ O ３ The source is aluminum-containing material, and Fe ２ O ３ The raw material composition can be adjusted by incorporating iron-containing materials as a source.
[0025] γ-2CaO・SiO ２ The method for preparing and mixing the raw material mixture for producing the calcined product can be any known method as appropriate. For example, the raw materials for CaO such as limestone, quicklime, and slaked lime, and SiO such as silica, can be prepared in advance. ２ Al raw materials, waste, etc. ２ O ３ Raw materials and Fe ２ O ３ The composition of the raw materials is measured, and the mixing ratio of each raw material is calculated from the proportion of each component in these raw materials to satisfy the above requirements, and the raw materials are then mixed according to that ratio.
[0026] While a smaller particle size in the raw material mixture increases the calcination reaction rate, it also worsens the power consumption per unit of pulverization of each raw material and / or the raw material mixture. Therefore, it is sufficient to prepare the mixture so that the residue after sieving at 90 μm is 10-30%, with 20-26% being preferable. The pulverization method for each raw material and / or the raw material mixture is not particularly limited and can be done using known methods.
[0027] The calcination temperature of the raw material mixture after preparation and mixing is not particularly limited as long as the amount of free lime (f-CaO) produced is 3.0% or less (preferably 1.0% or less). For example, it is preferably 1300 to 1600°C, more preferably 1300 to 1500°C, and even more preferably 1300 to 1450°C. Lower calcination temperatures tend to result in a higher amount of free lime (f-CaO), but if the raw material composition is Al ２ O ３ and Fe ２ O ３ When a large amount of is contained (for example, 5% or more in total), a sufficient amount of melt is generated during firing, which allows the firing temperature to be lowered, thereby reducing carbon dioxide emissions from fossil fuels during firing. The firing time depends on the firing temperature, but is generally 0.5 to 10 hours, preferably 1 to 5 hours.
[0028] The firing method is not particularly limited, and rotary kilns, shaft kilns, electric furnaces, tunnel furnaces, fluidized bed incinerators, etc., can be used. However, from the perspective of being able to use existing Portland cement manufacturing equipment, high-temperature heating equipment such as cement kilns represented by NSP kilns and SP kilns is preferably used. Furthermore, from the viewpoint of mass production, it is preferable to use such cement manufacturing equipment.
[0029] In this invention, a cooling operation is performed after firing, but the cooling conditions are not particularly limited. For example, when using existing Portland cement manufacturing equipment, the material can be immediately cooled after firing in a rotary kiln using a cooling device called a clinker cooler (a blower and a water sprayer).
[0030] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.
[0031] Raw material mixtures were prepared using reagent raw materials: calcium carbonate, silicon dioxide, aluminum oxide, and iron oxide. Each mixture was fired for 60 minutes at a firing temperature that resulted in a f-CaO content of 1.0% or less to obtain a fired product. Specifically, Comparative Example 1 was fired at 1450°C, Comparative Example 2 at 1400°C, Examples 1 and 2 at 1375°C, and Examples 3 to 6 and Comparative Examples 3 and 4 at 1350°C.
[0032] Table 1 shows the chemical composition of the raw material mixture after heating at 1000°C, as well as the mineral composition, Blaine specific surface area, and median diameter D of the resulting calcined product. ５０ This is shown. Note that in the table, γ-C ２ S is γ-2CaO·SiO ２ This represents β-C ２ S is β-2CaO·SiO ２ Represents C ２ AS is 2CaO·Al ２ O ３ SiO ２ Represents C ４ AF is 4CaO・Al ２ O ３ Fe ２ O ３ This represents the particle size distribution of the manufactured calcined products (Comparative Example 1, Comparative Example 2, Example 2, and Comparative Example 4).
[0033] The various measurement methods were as follows: (1) The chemical composition of the raw material mixture after heating to 1000°C was measured by X-ray fluorescence analysis in accordance with JIS R 5204. (2) The mineral composition of the calcined product was determined by X-ray diffraction analysis of the obtained calcined product and Rietveld analysis. (3) The Blaine specific surface area of the calcined product was measured by air permeation method. (4) The particle size distribution and median diameter D of the calcined product were measured. ５０ This was measured using a laser diffraction particle size distribution analyzer.
[0034]
[0035] γ-2CaO·SiO2 from Examples 1-7 ２ The calcined product containing C ４ The AF is 6.1 to 63.4 mass%, the Blaine specific surface area is large at 2000 or more, and the median diameter D ５０ The amount was also small. Therefore, the fired products of these examples have a carbonation-promoting effect and can shorten the carbonation curing period.
[0036] On the other hand, C ４ Comparative Examples 1 and 2, in which AF is less than 6% by mass, and C ４ Comparative Examples 3 and 4 with AF exceeding 65% by mass: γ-2CaO·SiO ２ The calcined material contains a small Blaine specific surface area of less than 2000, and a median diameter D ５０ The particles were also large, and therefore could not be expected to have a carbonation-promoting effect.
[0037] The present invention γ-2CaO・SiO ２ The calcined product containing this substance is useful as a cement admixture and is therefore industrially valuable.
Claims
1. 4CaO・Al ２ O ３ Fe ２ O ３ γ-2CaO・SiO is characterized by having a content of 6.0 to 65.0% by mass. ２ Containing fired product.
2. Brain specific surface area is 2000 cm² ２ The γ-2CaO・SiO2 described in claim 1 is characterized by being 1g or more. ２ Containing fired product.
3. γ-2CaO·SiO ２ The γ-2CaO·SiO according to claim 1, characterized in that the content of ２ is 20.0% by mass or more. ２ Containing calcined product.
4. 2CaO・Al ２ O ３ SiO ２ The γ-2CaO・SiO₂ according to claim 1 is characterized in that the content of is 3.0% by mass or less. ２ Containing fired product.
5. γ-2CaO・SiO2 according to any one of claims 1 to 4 ２ A method for producing a calcined product containing CaO and SiO as raw materials. ２ Al after heating to 1000°C, including the raw materials. ２ O ３ and Fe ２ O ３ The γ-2CaO・SiO is characterized by using a raw material mixture in which the total content of is 35.0% by mass or less. ２ Method for producing calcined products containing the active ingredient.
6. The above raw material mixture, on a mass basis, is equivalent to Fe after heating at 1000°C. ２ O ３ Al content ２ O ３ The γ-2CaO・SiO2 mixture according to claim 5 is characterized by being a raw material mixture in a quantity greater than the content. ２ Method for producing calcined products containing the active ingredient.
7. The γ-2CaO・SiO2 according to claim 5, characterized in that the raw material mixture is calcined at 1300 to 1600°C. ２ Method for producing calcined products containing the active ingredient.