Composite oxide for cement adjunct, method for manufacturing composite oxide for cement adjunct

Abstract

The present invention addresses the problem of providing a novel composite oxide for a cement adjunct and a method for manufacturing the composite oxide for a cement adjunct. The composite oxide for a cement adjunct according to the present invention contains CaO, MgO, Al2O3, and SiO2, wherein: a basicity B3, which is a value obtained by dividing the sum of the CaO content and the MgO and Al2O3 content by the SiO2 content, is 1.40 to 3.00; a value X, which is obtained by dividing the sum of the SiO2 content and the Al2O3 content by the CaO content, is 0.79 or greater; a value Y, which is obtained by dividing the sum of the CaO content and the SiO2 content by the Al2O3 content, is 1.37 or greater; and the total iron content is 8.0 mass% or less.

Description

Composite oxide for cement admixture, and method for producing composite oxide for cement admixture

[0001] The present invention relates to a composite oxide for use in a cement admixture, and also to a method for producing the composite oxide for use in a cement admixture.

[0002] Cement is widely used as a civil engineering material. Cement is often produced by mixing various composite oxides for cement admixtures. For example, Patent Document 1 describes the use of pulverized ordinary Portland cement clinker as a composite oxide for cement admixtures.

[0003] Japanese Patent Application Laid-Open No. 2019-131416

[0004] In recent years, there has been a demand for cement admixtures that are different from conventional ones. Therefore, an object of the present invention is to provide a novel composite oxide for a cement admixture. Another object of the present invention is to provide a method for producing the composite oxide for a cement admixture.

[0005] The present inventors have conducted extensive research to solve the above problems and have completed the present invention. That is, they have found that the above problems can be solved by the following configuration.

[0006] [1] CaO, MgO, Al ２ O ３ and SiO ２ Contains CaO content, MgO and Al ２ O ３ The sum of the content and SiO ２ The basicity B3, which is the value obtained by dividing by the content, is 1.40 to 3.00, and SiO ２ Content and Al ２ O ３ The value X obtained by dividing the sum of the CaO content and the SiO content by the CaO content is 0.79 or more, ２ The sum of the Al content ２ O ３A composite oxide for cement admixtures, wherein the value Y divided by the content is 1.37 or more, and the total iron content is 8.0 mass% or less. However, the unit of the content of each component is mass%. [2] The composite oxide for cement admixtures according to [1], wherein the value Y is 8.00 or less. [3] The composite oxide for cement admixtures according to [1] or [2], wherein the total iron content is 3.0 mass% or more. [4] CaO, MgO, Al ２ O ３ and SiO ２ Contains CaO content, MgO and Al ２ O ３ The sum of the content and SiO ２ The basicity B3, which is the value obtained by dividing by the content, is 1.40 to 3.00, and SiO ２ Content and Al ２ O ３ The value X obtained by dividing the sum of the CaO content and the SiO content by the CaO content is 0.79 or more, ２ The sum of the Al content ２ O ３ [5] A method for producing a composite oxide for a cement admixture according to [4], wherein an additive is added to melt reduced iron obtained by a direct reduction method in a submerged arc furnace to produce slag, thereby obtaining the composite oxide for a cement admixture, the method comprising the steps of: obtaining a composite oxide having a composition adjusted, the composition adjusted composite oxide having a value Y divided by the total iron content of 1.37 or more and a total iron content of 8.0 mass% or less; and quenching the molten composite oxide. [5] A method for producing a composite oxide for a cement admixture according to [4], wherein an additive is added to melt reduced iron obtained by a direct reduction method in a submerged arc furnace to produce slag, thereby obtaining the composite oxide having a composition adjusted.

[0007] According to the present invention, a novel composite oxide for a cement admixture can be provided, and also, a method for producing the composite oxide for a cement admixture can be provided.

[0008] The present invention will be described in detail below. The following description of the components may be based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.

[0009] The meaning of each description in this specification is explained below. Hereinafter, an embodiment of the present invention will be described in detail. However, the embodiment described below is an example, and the present invention is not limited to the embodiment described below. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​described before and after "to" as the lower and upper limits.

[0010] [Composite oxide for cement admixture] The composite oxide for cement admixture of the present invention (hereinafter also referred to as "composite oxide of the present invention") contains CaO, MgO, Al ２ O ３ and SiO ２ In addition, in the composite oxide of the present invention, the CaO content, MgO and Al ２ O ３ The sum of the content and SiO ２ The basicity B3, which is the value obtained by dividing the content by the amount of SiO, is 1.40 to 3.00. ２ Content and Al ２ O ３ The value X obtained by dividing the sum of the CaO content and the SiO content by the CaO content is 0.79 or more. ２ The sum of the Al content ２ O ３ The value Y obtained by dividing by the content is 1.37 or more. In the composite oxide of the present invention, the total iron content is 8.0 mass% or less. The content of each component is expressed in mass%. The composite oxide of the present invention will be described in detail below.

[0011] The composite oxide of the present invention is composed of CaO, MgO, Al ２ O ３ and SiO ２The content of CaO in the composite oxide of the present invention is not particularly limited as long as it satisfies the requirements of the basicity B3, the value X, and the value Y, but is preferably 15.0 mass% or more, more preferably 18.0 mass% or more, even more preferably 20.0 mass% or more, and particularly preferably 21.0 mass% or more, 24.0 mass% or more, 28.0 mass% or more, and 30.0 mass% or more, in the following order. The content of CaO is also preferably 60.0 mass% or less, more preferably 55.0 mass% or less, even more preferably 53.0 mass% or less, and particularly preferably 50.0 mass% or less, 48.0 mass% or less, 46.0 mass% or less, and 44.0 mass% or less, in the following order.

[0012] The content of MgO in the composite oxide of the present invention is not particularly limited as long as it satisfies the requirement of the basicity B3, but is preferably 2.0% by mass or more, more preferably 3.0% by mass or more, even more preferably 4.5% by mass or more, and particularly preferably 5.0% by mass or more, 5.3% by mass or more, 6.0% by mass or more, and 7.0% by mass or more, in the following order. The content of MgO is preferably 20.0% by mass or less, more preferably 18.0% by mass or less, even more preferably 16.0% by mass or less, and particularly preferably 15.0% by mass or less, 14.0% by mass or less, 13.0% by mass or less, and 12.0% by mass or less, in the following order.

[0013] Al in the composite oxide of the present invention ２ O ３ The content of Al is not particularly limited as long as it satisfies the requirements of the above basicity B3, the above value X, and the above value Y, but is preferably 8.0% by mass or more, more preferably 10.0% by mass or more, even more preferably 12.0% by mass or more, and particularly preferably 13.0% by mass or more, 14.0% by mass or more, 15.0% by mass or more, and 16.0% by mass or more, in that order. ２ O ３ The content is preferably 45.0% by mass or less, more preferably 40.0% by mass or less, even more preferably 36.0% by mass or less, and particularly preferably 35.0% by mass or less, 30.0% by mass or less, 27.0% by mass or less, and 25.0% by mass or less, in that order.

[0014] SiO in the composite oxide of the present invention ２ The content of is not particularly limited as long as the requirements for the basicity B3, the value X, and the value Y are satisfied, but is preferably 18.0% by mass or more, more preferably 20.0% by mass or more, even more preferably 23.0% by mass or more, and particularly preferably 24.0% by mass or more, 25.0% by mass or more, 26.0% by mass or more, and 27.0% by mass or more, in that order. ２ The content is preferably 50.0% by mass or less, more preferably 45.0% by mass or less, even more preferably 42.0% by mass or less, and particularly preferably 41.0% by mass or less, 40.0% by mass or less, 38.0% by mass or less, and 35.0% by mass or less, in the following order.

[0015] In the composite oxide of the present invention, the total iron content is 8.0 mass% or less. The total iron content is preferably 7.5 mass% or less, more preferably 7.0 mass% or less, even more preferably 6.5 mass% or less, and particularly preferably 6.0 mass% or less, 5.5 mass% or less, and 5.0 mass% or less, in order of decreasing the color of the composite oxide of the present invention. Furthermore, the total iron content in the composite oxide of the present invention is preferably 0.1 mass% or more, more preferably 0.2 mass% or more, even more preferably 0.3 mass% or more, and particularly preferably 0.5 mass% or more, 1.0 mass% or more, 2.0 mass% or more, and 3.0 mass% or more, in order of decreasing the total iron content. When the total iron content in the composite oxide of the present invention is reduced, it may be necessary to adjust the reaction conditions, etc., to increase the recovery rate of metallic iron in the reactor when melting an iron source such as reduced iron. Adjusting the total iron content to the above range is preferable because it improves the production efficiency of the reactor and reduces the load on the refractories used in the reactor. The total iron content is the amount of oxides (e.g., FeO, Fe ３ O ４ , Fe ２ O ３ The total content of iron (Fe) present in the form of iron, iron alloys, iron carbides ...

[0016] The content of each component in the composite oxide of the present invention is determined by XRF X-ray fluorescence analysis. Specifically, elemental analysis and composition analysis are performed by detecting fluorescent X-rays generated by irradiating X-rays and analyzing them with an energy or spectroscopic crystal. Note that, if the charge ratio when producing the composite oxide of the present invention is known, that value may be used.

[0017] In the composite oxide of the present invention, the CaO content, MgO and Al ２ O ３ The sum of the content and SiO ２ The basicity B3, which is the value obtained by dividing by the content, is 1.40 to 3.00. That is, the basicity B3 value, B3, can be calculated by the following formula (1).

[0018]

[0019] In the above formula (1), [CaO], [MgO], [Al ２ O ３ ] and [SiO ２ ] respectively represent CaO, MgO, and Al in the composite oxide of the present invention. ２ O ３ and SiO ２ The basicity B3 is the content value of Ca and Si, and is expressed in mass%. When the basicity B3 is 1.40 or more, when the components contained in the complex oxide of the present invention dissolve, Ca and Si components are eluted, facilitating the hydration reaction. From the viewpoint of latent hydraulic property, the basicity B3 is preferably 1.45 or more, more preferably 1.50 or more, even more preferably 1.60 or more, and particularly preferably 1.65 or more, 1.70 or more, 1.75 or more, and 1.80 or more, in the following order. Furthermore, when the basicity B3 is 3.00 or less, the complex oxide of the present invention has appropriate latent hydraulic property, and when mixed with cement, concrete formed containing the complex oxide of the present invention can sufficiently exhibit strength. From the viewpoint of vitrification rate, the basicity B3 is preferably 2.95 or less, more preferably 2.90 or less, even more preferably 2.80 or less, and particularly preferably 2.70 or less, 2.60 or less, 2.50 or less, and 2.40 or less, in the following order.

[0020] In the composite oxide of the present invention, SiO ２ Content and Al２ O ３ The value X obtained by dividing the sum of the content of CaO and the content of Cr by the content of CaO is 0.79 or more. That is, the value X can be calculated by the following formula (2).

[0021]

[0022] In the above formula (2), [CaO], [Al ２ O ３ ] and [SiO ２ ] respectively represent the amounts of CaO and Al in the composite oxide of the present invention. ２ O ３ and SiO ２ The value of the content of X is expressed in mass %. When the value X is 0.79 or more, the vitrification rate of the composite oxide of the present invention tends to be high. The value X is preferably 0.80 or more, more preferably 0.85 or more, even more preferably 0.90 or more, and particularly preferably 0.95 or more, 1.00 or more, 1.05 or more, and 1.10 or more, in the following order. There is no particular upper limit for the value X, but examples include 5.00 or less, preferably 4.00 or less, more preferably 3.50 or less, and even more preferably 3.00 or less, 2.80 or less, 2.60 or less, and 2.20 or less, in the following order.

[0023] In the composite oxide of the present invention, the CaO content and SiO ２ The sum of the Al content ２ O ３ The value Y divided by the content is 1.37 or more. That is, the value Y can be calculated by the following formula (3).

[0024]

[0025] In the above formula (3), [CaO], [Al ２ O ３ ] and [SiO ２ ] respectively represent the amounts of CaO and Al in the composite oxide of the present invention. ２ O ３ and SiO ２The value of the content of Y is expressed in mass %. If the value Y is 1.37 or more, the composite oxide of the present invention is likely to have a granular shape when obtained. The value Y is preferably 1.40 or more, more preferably 1.50 or more, even more preferably 1.70 or more, and particularly preferably 1.90 or more, 2.10 or more, 2.50 or more, and 2.80 or more, in that order. There is no particular upper limit to the value Y, but examples include 10.00 or less, preferably 8.00 or less, more preferably 7.00 or less, and even more preferably 6.50 or less, 6.00 or less, 5.60 or less, and 5.00 or less, in that order.

[0026] The average particle size of the composite oxide of the present invention is preferably 1 to 100 μm in view of its use as a cement admixture. The specific surface area of ​​the composite oxide of the present invention is preferably 3,000 to 10,000 cm ２ / g or more is preferred. The specific surface area of ​​the composite oxide of the present invention is measured by the Blaine method. The composite oxide of the present invention preferably has a high whiteness. The whiteness of the composite oxide of the present invention is preferably greater than 20, and may be greater than 55. The whiteness refers to ISO whiteness.

[0027] The vitrification rate of the complex oxide of the present invention is preferably 90.0% or more, more preferably 91.0% or more, and even more preferably 92.0% or more. The upper limit of the vitrification rate is 100.0% or less, and in many cases is 99.9% or less. The vitrification rate of the complex oxide of the present invention is measured according to a polarizing microscope observation method. Specifically, a thin sample of the complex oxide is prepared and observed using a polarizing microscope with crossed polars to measure the vitrification rate (%) of the complex oxide.

[0028] The method for producing the composite oxide of the present invention is not particularly limited as long as it satisfies the above-mentioned requirements. For example, the composite oxide of the present invention can be produced by the method for producing the composite oxide of the present invention described below. It is preferable that the composite oxide of the present invention is obtained by the method for producing the composite oxide of the present invention described below.

[0029] [Method for producing a composite oxide for cement admixture] The method for producing a composite oxide for cement admixture of the present invention is to produce a composite oxide containing CaO, MgO, Al ２ O３ and SiO ２ Contains CaO content, MgO and Al ２ O ３ The sum of the content and SiO ２ The basicity B3, which is the value obtained by dividing by the content, is 1.40 to 3.00, and SiO ２ Content and Al ２ O ３ The value X obtained by dividing the sum of the CaO content and the SiO content by the CaO content is 0.79 or more, ２ The sum of the Al content ２ O ３ A composition-adjusted composite oxide is obtained in which the value Y divided by the iron content is 1.37 or more and the total iron content is 8.0 mass% or less, and the molten composition-adjusted composite oxide is quenched. According to the method for producing a composite oxide for a cement admixture of the present invention (hereinafter also referred to as the "production method of the present invention"), the above-mentioned composite oxide of the present invention can be obtained. The production method of the present invention will be described below. Note that, hereinafter, the step of obtaining the composition-adjusted composite oxide will also be referred to as the composition adjustment step, and the step of quenching the molten composition-adjusted composite oxide will also be referred to as the quenching step. Each step will be described below.

[0030] In the manufacturing method of the present invention, the above-mentioned component adjusting step is first carried out. In the component adjusting step, CaO, MgO, Al ２ O ３ and SiO ２A composition-adjusted composite oxide is obtained, in which the basicity B3, the value X, and the value Y are within predetermined ranges. The definitions of the basicity B3, the value X, and the value Y in the composition-adjusted composite oxide are the same as those in the composite oxide of the present invention described above, and therefore will not be described here. The preferred ranges of the content of each component and the preferred ranges of the basicity B3, the value X, and the value Y in the production method of the present invention are the same as those in the composite oxide of the present invention described above, and therefore will not be described here. In the composition adjustment step, the type and amount of additives used in the composition adjustment are adjusted so that the basicity B3, the value X, and the value Y fall within the predetermined ranges. As described above, the total iron content in the composition-adjusted composite oxide is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, even more preferably 0.3% by mass or more, and particularly preferably 0.5% by mass or more, 1.0% by mass or more, 2.0% by mass or more, and 3.0% by mass or more, in that order. In addition, when the total iron content in the composition-adjusted composite oxide is reduced, it may be necessary to adjust the reaction conditions, etc., so as to increase the recovery rate of metallic iron in the reactor when melting an iron source such as reduced iron. Adjusting the total iron content to the above range is preferable, as it improves the production efficiency of the reactor and reduces the load on the refractories used in the reactor.

[0031] The method for carrying out the composition adjustment step is not particularly limited as long as the composition-adjusted composite oxide can be obtained. The composition-adjusted composite oxide may be obtained in a solid state or a molten state. Examples of methods for carrying out the composition adjustment step include a method of mixing and melting the solid components of each of the components, and a method of mixing and melting a composite oxide containing each of the components in solid form. The composition adjustment step may also be carried out by adding the solid components of each of the components or the solid composite oxide containing each of the components to a molten composite oxide or a melt of each of the components.

[0032] Another example of a method for implementing the composition adjustment step is a method using slag generated in a metal smelting or refining process as a raw material. Iron is a preferred example of the metal. That is, steel slag may be used as a raw material. Alternatively, the composition adjustment step may be implemented by adjusting the composition of slag (e.g., steel slag) generated in a metal smelting or refining process. The steel slag is not particularly limited, and examples include blast furnace slag, converter slag, electric furnace slag, slag generated by a direct ironmaking process, and slag generated by a smelting reduction ironmaking process. Examples of composition adjustment methods include a method of mixing the solid simple substance of each of the above components with the steel slag, a method of mixing a composite oxide containing the solid of each of the above components with the steel slag, and a method of mixing another steel slag with the steel slag. In addition, as a method for adjusting the composition, when the components that will become the steel slag are added to produce slag, a simple solid form of each of the components may be added, a composite oxide containing a solid form of each of the components may be added, or one or more types of other steel slag may be added.

[0033] The blast furnace slag includes slag with a lower density than pig iron that is recovered when iron is recovered from iron ore charged into a blast furnace by a reduction process in which coke, limestone, etc. are added to the iron ore. The blast furnace slag also includes slag that is a by-product of the so-called blast furnace-converter process. The electric furnace slag includes slag that is a by-product of the electric furnace steelmaking process. In the electric furnace steelmaking process, a cold iron source (e.g., scrap, reduced iron, etc.) is generally heated and melted using electricity.

[0034] In particular, the method for carrying out the composition adjustment step is preferably a method of adjusting the composition of steel slag and then carrying out the composition adjustment step, and more preferably a method of adding additives to generate slag when melting reduced iron obtained by a direct reduction method in an electric furnace (more preferably a submerged arc furnace), thereby obtaining a composite oxide with the composition adjusted. Examples of the additives include the simple substances of each of the above components and composite oxides containing each of the above components. More specifically, lime (CaO), silica sand (SiO ２), magnesium oxide (MgO), etc., and complex oxide by-products containing these (for example, slag, used brick waste, dust, etc.).

[0035] Although the above description has focused on steel slag as a raw material for the slag produced in the metal smelting or refining process, other slags may also be used, such as non-ferrous metal slags such as ferronickel slag and copper slag, as well as waste melting slag and sewage sludge slag.

[0036] In the production method of the present invention, a quenching step is carried out in which the molten composite oxide with its composition adjusted is rapidly cooled. The composite oxide with its composition adjusted is as described above. The quenching step can be carried out by a known method, for example, a method in which a refrigerant is sprayed onto the molten composite oxide with its composition adjusted to cool it. The refrigerant may be a liquid or a gas. Examples of the liquid include water. Examples of the gas include inert gases such as argon gas and nitrogen gas, and air. The flow rate when spraying the refrigerant can be adjusted as appropriate.

[0037] The rapid cooling step makes it easy to obtain a complex oxide with a high vitrification rate. The preferred range of the vitrification rate of the complex oxide is as described above. Furthermore, by using the above-mentioned composite oxide with adjusted composition, a granular complex oxide is easily obtained after the rapid cooling step. Granular means that the composite oxide is not fibrous, and specifically means that the ratio of the major axis to the minor axis (major axis / minor axis) is 10.0 or less.

[0038] In addition, when a solid composite oxide with composition adjustment is obtained in the composition adjustment step, the composition adjusted composite oxide is melted and then subjected to the rapid cooling step.

[0039] The manufacturing method of the present invention may include other steps in addition to the component adjusting step and the quenching step. For example, it may include a particle size adjusting step for adjusting the particle size of the composite oxide obtained in the quenching step. The method for performing the particle size adjusting step is not particularly limited, and examples thereof include a method in which the composite oxide obtained by a known pulverizing method is pulverized. The preferred particle size of the composite oxide after pulverization is as described above. Examples of pulverizing methods include a ball mill, a pin mill, and a jet mill. Furthermore, after pulverizing the composite oxide, it may be classified by a known classification method. Examples of classification methods include dry classification, and more specifically, sieving and air classification.

[0040] [Use of the composite oxide for cement admixture] The composite oxide for cement admixture (composite oxide) of the present invention is used as a cement admixture. Hereinafter, cement containing the composite oxide of the present invention will be described.

[0041] The composite oxide of the present invention is preferably used, for example, as an admixture for blended cement. The blended cement contains the composite oxide of the present invention and other components. Examples of the other components include Portland cement. The Portland cement may be ordinary Portland cement, which may contain cement clinker. Other components include high-early-strength Portland cement, which develops strength in a shorter period of time, moderate-heat Portland cement, which has a low calorific value, and low-heat Portland cement.

[0042] In the mixed cement, the content of the composite oxide is preferably 10 to 90% based on the total mass of the composite oxide and other compositional components.

[0043] The present invention will be described in more detail below with reference to examples. The materials, amounts used, ratios, treatment details, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the examples shown below.

[0044] [Example 1] <Production of composite oxide> Remelted blast furnace slag was treated with a CaO reagent, SiO ２ Reagents, Al ２ O ３ reagent, MgO reagent, and Fe ３ O ４ The amounts of the reagents were adjusted to the ratios shown in Table 1 below, and a composite oxide with adjusted composition was obtained. Water was sprayed onto the molten composite oxide with adjusted composition to rapidly cool and solidify it, yielding a composite oxide. The composite oxide obtained had a specific surface area of ​​3000 to 5000 cm. ２ The composite oxide was finely pulverized to a basicity B3 of 0.01g / g. The basicity B3, value X, and value Y of the obtained composite oxide were calculated using the above-mentioned formulas (1) to (3). The results are shown in Table 1 below.

[0045] <Measurement> The vitrification rate of the obtained composite oxide of Example 1 was measured by the method described above. The results are shown in Table 1 below.

[0046] The activity index of the composite oxide obtained in Example 1 was also measured at ages of 7, 28, and 91 days. The activity index of the composite oxide at ages of 7, 28, and 91 days was measured in accordance with JIS A 6206-2:2010, "Ground granulated blast furnace slag for concrete." Specifically, the activity index was calculated by dividing the compressive strength of a 40 mm x 40 mm x 160 mm prismatic mortar made by substituting 50% by mass of ordinary cement with the composite oxide by the compressive strength of a mortar made using only ordinary cement. Specifically, the compressive strength of the mortar made by substituting 50% by mass of cement with the composite oxide and the compressive strength of a mortar made using only cement were measured, and the activity index of the composite oxide was measured. The activity index results are shown in Table 1 below.

[0047] [Examples 2 to 22] Composite oxides were obtained in the same manner as in Example 1, except that the amounts of the above-mentioned reagents added were adjusted so that the contents of the respective components constituting the composite oxides were the values ​​shown in Table 1 below. Furthermore, the vitrification rate and activity index were measured in the same manner as in Example 1.

[0048] [Examples 23 to 33] Composite oxides were obtained in the same manner as in Example 1, except that the amounts of the above-mentioned reagents added were adjusted so that the contents of the components constituting the composite oxides were the values ​​shown in Table 1 below, and the composite oxides were rapidly cooled and solidified by blowing air. Furthermore, the vitrification rate and activity index were measured in the same manner as in Example 1.

[0049] Comparative Examples 1 to 12 Composite oxides were obtained in the same manner as in Example 1, except that the amounts of the above-mentioned reagents added were adjusted so that the contents of the respective components constituting the composite oxides were the values ​​shown in Table 1 below. Furthermore, the vitrification rate and activity index were measured in the same manner as in Example 1.

[0050] [Results] The compositions and measurement results of the composite oxides of the examples and comparative examples are shown in Table 1 (parts 1 and 2). In Table 1, the "T.Fe" column represents the total iron content. In Table 1, the "Properties of composite oxide after quenching" column represents the properties of the composite oxide immediately after quenching each of the composite oxides. The "Appearance" column indicates the shape of the composite oxide, and when the ratio of the major axis to the minor axis of the composite oxide is greater than 10.0, it is described as "fibrous," and when the ratio is 10.0 or less, it is described as "granular." In addition, in Table 1, the "Color" column indicates that an ISO whiteness index of more than 55 is white, when it is greater than 20 and less than or equal to 55, it is "gray-white to blue," and when it is 20 or less, it is "black."

[0051]

[0052]

[0053] From the results shown in Table 1, it was confirmed that the composite oxides of Examples 1 to 33 had a higher vitrification rate and a superior activity index at a material age of 91 days compared to the composite oxides of Comparative Examples 1 to 12.

[0054] The composite oxide for a cement admixture of the present invention is suitable as a cement raw material and is expected to be used in a variety of industrial fields.

Claims

1. CaO, MgO, Al ２ O ３ and SiO ２ Contains CaO content, MgO and Al ２ O ３ The sum of the content and SiO ２ The basicity B3, which is the value obtained by dividing by the content, is 1.40 to 3.00, and SiO ２ Content and Al ２ O ３ The value X obtained by dividing the sum of the CaO content and the SiO content by the CaO content is 0.79 or more, ２ The sum of the Al content ２ O ３ A composite oxide for cement admixture, wherein the value Y divided by the iron content is 1.37 or more, and the total iron content is 8.0 mass% or less, where the unit of the content of each component is mass%.

2. The composite oxide for cement admixture according to claim 1, wherein the value Y is 8.00 or less.

3. The composite oxide for cement admixture according to claim 1 or 2, wherein the total iron content is 3.0 mass % or more.

4. CaO, MgO, Al ２ O ３ and SiO ２ Contains CaO content, MgO and Al ２ O ３ The sum of the content and SiO ２ The basicity B3, which is the value obtained by dividing by the content, is 1.40 to 3.00, and SiO ２ Content and Al ２ O ３ The value X obtained by dividing the sum of the CaO content and the SiO content by the CaO content is 0.79 or more, ２ The sum of the Al content ２ O ３ A method for producing a composite oxide for a cement admixture, comprising: obtaining a composition-adjusted composite oxide in which a value Y divided by the iron content is 1.37 or more and a total iron content is 8.0 mass% or less; and quenching the composition-adjusted composite oxide in a molten state.

5. A method for producing a composite oxide for a cement admixture according to claim 4, wherein when reduced iron obtained by a direct reduction method is melted in a submerged arc furnace, an additive is added to produce slag, thereby obtaining the composite oxide with adjusted composition.

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