Γ-2 cao∙sio2-containing fired product and method for producing same

Abstract

This γ-2 CaO∙SiO2-containing fired product is characterized by satisfying the following requirements a) and b).　a) C' / S' (molar ratio) represented by {[CaO]-2([Al2O3]+[Fe2O3])} / {[SiO2]-([Al2O3]-[Fe2O3])} is 1.90-2.10.　b) Al2O3 is 25.00 mass% or less.

Description

γ-2CaO·SiO2-containing fired product and its manufacturing method

[0001] The present invention is a γ-2CaO.SiO ２ and a method for producing the same.

[0002] In recent years, the trend towards decarbonization has been accelerating worldwide, and this trend is also gaining momentum in the cement industry, a typical high-consumption industry. In this context, 2CaO・SiO ２ The γ type of γ-2CaO.SiO has been attracting attention in recent years, and many studies have been conducted on its use. For example, γ-2CaO.SiO ２ It is known that by forcibly carbonating and curing concrete containing the above-mentioned mineral admixture, it is possible to obtain highly durable concrete with a densified surface layer, and its usefulness has been discovered in recent years (Patent Document 1).

[0003] On the other hand, in relation to recent global environmental problems, the effective utilization of waste has become an important issue. Taking advantage of the characteristics of the cement industry and cement manufacturing facilities, the effective utilization or treatment of waste as raw materials or thermal energy sources in the production of cement clinker is considered effective from the perspective of safe and large-scale disposal.

[0004] Among waste materials, coal ash, municipal waste incineration ash, granulated blast furnace slag, and slowly cooled blast furnace slag are used. Compared to the composition of ordinary cement clinker, coal ash in particular has a higher Al content. ２ O ３ Therefore, if the amount of such waste material used is increased, the amount of 3CaO·Al, which is the void phase of the cement clinker components, will increase. ２ O ３ The content of Al increases, which affects the physical properties of cement. Therefore, the amount of waste used in cement production is ２ O ３ There is a problem that it cannot be used in large quantities due to the limitations imposed by the amount of components. ２ It is highly likely that effective utilization of waste will be required in the manufacturing of

[0005] However, γ-2CaO.SiO ２In the production of Al ２ O ３ When γ-2CaO.SiO ２ Instead, β-2CaO.SiO ２ It is known that Al is easily produced when the raw material mixture is heated to 1000°C (see, for example, Patent Document 2). ２ O ３ and FeO ３ When the total content of β-2CaO.SiO is 5.0 mass% or more, ２ is produced, and γ-2CaO.SiO ２ It is described that the purity of

[0006] JP 2006-182583 A International Publication No. 2012 / 099254

[0007] γ-2CaO.SiO described in Patent Document 2 ２ The manufacturing method of Al ２ O ３ and FeO ３ The total content of Al is limited to less than 5 mass %. ２ O ３ It is not possible to recycle waste materials such as concrete sludge, waste concrete, and steelmaking slag, which contain large amounts of these metals.

[0008] The object of the present invention is to ２ O ３ A specified amount of γ-2CaO.SiO can be used as raw material from waste with a high content. ２ The present invention provides a fired product containing the above compound and a method for producing the same.

[0009] Conventionally, γ-2CaO.SiO ２ is C / S (CaO / SiO ２ The composition is adjusted so that the molar ratio of Al is 2.0. ２ O ３ When waste materials with a high content of β-2CaO.SiO (including by-products from cement manufacturing, etc.) are used as part of the raw materials, adjusting the C / S ratio to 2.0 results in β-2CaO.SiO. ２ It was found that a large amount of

[0010] Therefore, the present inventors have further studied based on this finding, and as a result, instead of using this C / S index as it is, ２ O ３ , and FeO which reacts with it ３ By using a new index that takes into account ２ The formation of a predetermined amount of γ-2CaO.SiO ２ The present inventors have found that a fired product containing the above compound can be obtained, and have thus completed the present invention.

[0011] Specifically, Al ２ O ３ CaO, SiO ２ and Fe ２ O ３ It reacts with 4CaO.Al ２ O ３ Fe ２ O ３ (C ４ AF) and 2CaO·Al ２ O ３ SiO ２ (C ２ AS), CaO and SiO ２ By changing the quantitative relationship (C / S) of these C ４ AF and C ２ We found that the composition can be designed taking into account the coexistence of AS.

[0012] That is, the present invention is as follows: [1] A γ-2CaO.SiO2 powder characterized by satisfying the following requirements a) and b): ２ a) {[CaO]-2([Al ２ O ３ ]+[Fe ２ O ３ ]))} / {[SiO ２ ]-([Al ２ O ３ ]-[Fe ２ O ３ ]))) is 1.90 to 2.10. ２ O ３ is 25.00 mass% or less.

[0013] [2] b) Al２ O ３ is more than 5.00 mass% and not more than 25.00 mass%. ２ Containing fired product. [3] γ-2CaO・SiO ２ The γ-2CaO.SiO according to the above [1] or [2], characterized in that the content of ２ [4] The γ-2CaO.SiO2-containing fired product according to any one of [1] to [3] above, which is a cement admixture. ２ Containing fired product.

[0014] [5] The γ-2CaO.SiO according to any one of [1] to [4] above. ２ A method for producing a calcined product containing CaO, SiO ２ A γ-2CaO.SiO2 composite is produced by firing a raw material mixture containing raw materials and waste materials at a firing temperature of 1280°C to 1600°C. ２ [6] A method for producing a γ-2CaO.SiO-containing fired product according to the above [5], characterized in that the waste is at least one waste selected from coal ash, blast furnace slag, steelmaking slag, concrete sludge, waste concrete, incineration fly ash, and municipal waste incineration ash. ２ Method for producing a fired product containing the compound.

[0015] According to the present invention, conventional CaO raw materials and SiO ２ In addition to the raw materials, γ-2CaO・SiO ２ It is possible to use waste as part of the raw material for producing Al ２ O ３ Even when waste with a high content is used as raw material, β-2CaO.SiO ２ By suppressing the generation of γ-2CaO.SiO ２ Therefore, according to the present invention, it is possible to more effectively utilize waste materials. In particular, compared to the cement clinker composition, the Al content of the burned product is much lower. ２ O ３ Its high content makes it effective for utilizing waste materials that are subject to restrictions on the amount that can be used in cement production.

[0016] FIG. 1 is a diagram showing the concept underlying condition a) in the present invention.

[0017] The gamma-2CaO.SiO of the present invention ２ The calcined product is characterized by satisfying the following requirements a) and b).

[0018] a) {[CaO]-2([Al ２ O ３ ]+[Fe ２ O ３ ]))} / {[SiO ２ ]-([Al ２ O ３ ]-[Fe ２ O ３ ]))) is 1.90 to 2.10. ２ O ３ is 25.00 mass% or less.

[0019] The gamma-2CaO.SiO of the present invention ２ In the fired product containing Al ２ O ３、 and FeO which reacts with it ３ The significance of the indicator shown in a) above will be explained below.

[0020] First, CaO, SiO ２ , Al ２ O ３ and Fe ２ O ３ When a raw material containing the above is used, the reaction is generally thought to occur in the following order (1) to (3). A schematic diagram of this reaction is shown in Figure 1.

[0021] (1) Fe ２ O ３ But, Al ２ O ３ and reacts with CaO to form C ４ Form AF. (2) C ４ The remaining Al after forming AF ２ O ３ is CaO and SiO ２ reacts with C ２ Form AS. (3) C ４ AF and C ２The remaining CaO after forming AS is SiO ２ reacts with 2CaO.SiO ２ (C ２ S).

[0022] CaO and SiO in (3) ２ The molar ratio (C / S) is adjusted to about 2.00.

[0023] Specifically, CaO reacts with Fe in the reaction (1) above. ２ O ３ In reaction (2), the unreacted Al in (1) is consumed in a molar amount four times the amount of Al contained in (1). ２ O ３ Amount ([Al ２ O ３ ]-[FeO ３ ]) is consumed in a molar amount twice as large as that of SiO ２ is the unreacted Al in the reaction (1) in the reaction (2). ２ O ３ Amount ([Al ２ O ３ ]-[FeO ３ ]) are consumed in equimolar amounts. After this consumption, the remaining CaO and SiO ２ The composition is designed so that the molar ratio of C' / S' is about 2.00 (1.90 to 2.10, preferably 1.93 to 2.07, more preferably 1.95 to 2.05). The balance of the above is shown in Table 1 below.

[0024]

[0025] The results of Example 5 described later can be applied to Table 1 as follows.

[0026]

[0027] The gamma-2CaO.SiO of the present invention ２ In the fired product containing Al, b) ２ O ３ is 25.00 mass% or less. ２ O ３ If the content of C exceeds 25.00 mass%, a large amount of C ２ AS and C ４ AF is generated, and γ-2CaO.SiO ２It is not possible to obtain a fired product containing a sufficient amount of Al. ２ O ３ is preferably 22.00 mass% or less. ２ O ３ There is no particular lower limit to the content, but it is, for example, 2.00 mass% or more, and even if the content is as high as more than 5.00 mass%, γ-2CaO.SiO ２ A fired product containing a sufficient amount of

[0028] The gamma-2CaO.SiO of the present invention ２ In the fired product containing Fe, ２ O ３ / Al ２ O ３ (molar ratio) is preferably 0.05 to 1.10. ２ O ３ / Al ２ O ３ If the value exceeds 1.1, depending on other requirements, a large amount of β-2CaO.SiO ２ is produced, and γ-2CaO.SiO ２ In some cases, it may not be possible to obtain a fired product containing a sufficient amount of Fe. ２ O ３ / Al ２ O ３ The molar ratio is more preferably 0.05 to 0.90, and even more preferably 0.25 to 0.90. ２ O ３ / Al ２ O ３ When the molar ratio is high, a melt is generated during firing, which allows the firing temperature to be lowered.

[0029] The gamma-2CaO.SiO of the present invention ２ The contained fired material is γ-2CaO.SiO ２ The content of β-2CaO.SiO is preferably 25.0% by mass or more, more preferably 30.0% by mass or more, even more preferably 40.0% by mass or more, and particularly preferably 50.0% by mass or more. ２ From γ-2CaO.SiO ２ It is preferable that the content is high.

[0030] The γ-2CaO.SiO of the present invention produced as described above ２ The calcined product containing the carbon dioxide can be used, for example, as an admixture for cement. Concrete or mortar using cement containing the calcined product undergoes carbonation curing during production, which densifies the surface layer and improves durability. Furthermore, in the production of this concrete, carbon dioxide is absorbed into the concrete during carbonation curing, which makes it possible to reduce carbon dioxide emissions when obtaining concrete products.

[0031] The gamma-2CaO.SiO of the present invention ２ The raw materials for obtaining the calcined product include CaO raw material, SiO ２ Raw materials and Al ２ O ３ and Fe ２ O ３ Waste containing

[0032] In the present invention, waste materials are used as raw materials, and therefore waste materials can be effectively utilized. ２ The Al-containing fired product allows for the use of a larger amount of waste as a raw material. ２ O ３ Even when waste with a high content of β-2CaO.SiO is used as the raw material, ２ By suppressing the formation of γ-2CaO.SiO ２ A fired product containing a high proportion of

[0033] CaO raw material and SiO ２ The raw materials are CaO raw material and SiO ２ The raw materials can be used without any restrictions, specifically, CaO raw materials such as limestone, quicklime, and slaked lime, SiO raw materials such as silica stone and silica fume, ２ Limestone (calcium carbonate) used as a CaO raw material emits carbon dioxide when burned, but in the present invention, by using waste materials such as concrete sludge and blast furnace slag containing calcium oxide that can be used as a CaO raw material, the amount of limestone used, which causes carbon dioxide emissions, can be reduced, and γ-2CaO.SiO２ Carbon dioxide emissions during production can be reduced.

[0034] The waste material in this invention refers to waste materials and by-products used in cement production, etc. Usable waste materials are not particularly limited, but specific examples include blast furnace slag such as granulated blast furnace slag and slowly cooled blast furnace slag, steelmaking slag, non-ferrous slag, coal ash, concrete sludge (including returned concrete and remaining concrete), waste concrete, sewage sludge, water purification sludge, papermaking sludge, construction soil, foundry sand, soot and dust, incineration fly ash, molten fly ash, chlorine bypass dust, wood chips, waste clay, slag, waste tires, shells, municipal waste and its incineration ash (some of these can also be used as a thermal energy source). Among these, Al, which is used in the production of cement clinker, is particularly preferred. ２ O ３ The amount of Al used is limited by the amount of ２ O ３ Waste containing Al is preferred in that it further promotes the effective utilization of waste. ２ O ３ Typical wastes containing Al include blast furnace slag, steelmaking slag, non-ferrous slag, coal ash, concrete sludge, waste concrete, sewage sludge, water purification sludge, paper sludge, foundry sand, incineration fly ash, molten fly ash, municipal waste and its incineration ash, etc. Among these, compared to ordinary cement clinker compositions, Al ２ O ３ Its content is high, and its main components are CaO and SiO ２ , Al ２ O ３ From this viewpoint, it is preferable to use coal ash, blast furnace slag, steelmaking slag, concrete sludge, waste concrete, incineration fly ash, and municipal waste incineration ash. These wastes may also be used in combination.

[0035] γ-2CaO.SiO ２ The raw material mixture for producing the calcined product may be prepared by any known method. For example, a CaO raw material such as limestone, quicklime, or slaked lime, a SiO raw material such as silica stone, or the like may be prepared in advance. ２The compositions of the raw materials and waste materials are measured, and the blending ratio of each raw material is calculated from the proportion of each component in these raw materials so as to satisfy the requirements a) and b) of the present invention, and the raw materials are blended in that ratio.

[0036] CaO raw material, SiO ２ The smaller the particle size of the raw material mixture containing raw materials and waste materials, the faster the firing reaction rate, but since the power consumption rate generated during pulverization of each raw material and / or raw material mixture increases, the 90 μm sieve residue should be adjusted to 10 to 30%, preferably 20 to 26%. The pulverization method for each raw material and / or raw material mixture is not particularly limited, and pulverization can be performed by a known method.

[0037] In the present invention, the firing temperature of the raw material mixture after preparation and mixing is preferably 1280 to 1600°C, more preferably 1350 to 1500°C. If the firing temperature is low, the amount of free lime (f-CaO) tends to increase. The free lime content is preferably less than 3.0 mass%, more preferably 1.5 mass% or less. Conversely, if the firing temperature is too high, the raw materials will melt and vitrify, making operation difficult and also undesirable from the viewpoint of thermal energy consumption. The firing time, although depending on the firing temperature, is generally 0.5 to 10 hours, preferably 1 to 5 hours.

[0038] The calcination method is not particularly limited, and rotary kilns, shaft kilns, electric furnaces, tunnel kilns, fluidized bed incinerators, etc. can be used, but from the viewpoint of being able to use existing Portland cement manufacturing equipment, devices capable of high temperature heating, such as cement kilns represented by NSP kilns and SP kilns, are preferably used. Furthermore, from the viewpoint of mass production, it is preferable to use such cement manufacturing equipment.

[0039] In the present invention, a cooling operation is carried out after firing, but the cooling conditions are not particularly limited. For example, in existing Portland cement manufacturing facilities, after firing in a rotary kiln, cooling can be carried out immediately using a cooling device called a clinker cooler (including a blower and a water sprinkler).

[0040] The configuration and effects of the present invention will be explained below using examples, but the present invention is not limited to these examples.

[0041] [Examples 1 to 6 and Comparative Examples 1 to 12] Limestone and SiO ２ A raw material mixture was prepared using silica stone as the raw material and concrete sludge as the waste material, and fired in an electric furnace at 1450°C for 60 minutes to obtain γ-2CaO.SiO of the specified composition. ２ Table 3 shows the chemical compositions of the raw materials, and Table 4 shows the chemical and mineral compositions of the resulting fired products.

[0042] In addition, γ-2CaO.SiO ２ The chemical composition of the fired material was measured by fluorescent X-ray analysis in accordance with JIS R 5204. ２ The mineral composition of the fired material was determined by subjecting the fired material to X-ray diffraction analysis and Rietveld analysis.

[0043]

[0044]

[0045] (Sludge blending ratio: 30%) The compositions of Examples 1 to 3 according to the present invention (C' / S' = 1.90 to 2.10) contain β-2CaO.SiO ２ The content of γ-2CaO.SiO ２ On the other hand, the compositions of Comparative Examples 1 to 4 (C' / S' less than 1.90 or more than 2.10) contain a large amount of β-2CaO.SiO ２ is produced in large amounts, and γ-2CaO.SiO ２ The content is low.

[0046] (Sludge blending ratio: 40%) The compositions of Examples 4 to 6 according to the present invention (C' / S' = 1.90 to 2.10) contain β-2CaO.SiO ２ The content of γ-2CaO.SiO ２ On the other hand, the compositions of Comparative Examples 5 to 8 (C' / S' less than 1.90 or more than 2.10) contain a large amount of β-2CaO.SiO ２ is produced in large amounts, and γ-2CaO.SiO ２ The content is low.

[0047] [Examples 7 to 18] Special grade reagent Al was used instead of concrete sludge. ２ O ３ and FeO ３ The raw material mixture was prepared using the above and fired in an electric furnace at 1450°C for 60 minutes to obtain γ-2CaO.SiO ２ Tables 5 and 6 show the chemical and mineral compositions of the obtained fired products. Examples 7 to 12 shown in Table 5 contain Al ２ O ３ The contents of FeO were changed, and Examples 13 to 18 shown in Table 6 ３ / Al ２ O ３ The molar ratio was changed.

[0048]

[0049]

[0050] As shown in Table 5, the compositions of Examples 7 to 12 according to the present invention (C' / S' = 1.90 to 2.10) contained Al ２ O ３ Even if the amount of β-2CaO.SiO increases, ２ The content of γ-2CaO.SiO ２ It has a high content of

[0051] As shown in Table 6, the compositions of Examples 13 to 18 according to the present invention (C' / S' = 1.90 to 2.10) contained FeO ３ / Al ２ O ３ Even if the molar ratio increases, β-2CaO.SiO ２ The content of γ-2CaO.SiO ２ It has a high content of

[0052] The gamma-2CaO.SiO of the present invention ２ The calcined product containing the sintered material can be used as a cement admixture, and is therefore industrially useful.

Claims

1. γ-2CaO.SiO2 characterized by satisfying the following requirements a) and b): ２ a) {[CaO]-2([Al ２ O ３ ]+[Fe ２ O ３ ]))} / {[SiO ２ ]-([Al ２ O ３ ]-[Fe ２ O ３ ]))) is 1.90 to 2.

10. ２ O ３ is 25.00 mass% or less.

2. Above b) Al ２ O ３ is more than 5.00 mass% and not more than 25.00 mass% of the γ-2CaO.SiO ２ Containing fired product.

3. γ-2CaO・SiO ２ 2. The γ-2CaO.SiO according to claim 1, wherein the content of ２ Containing fired product.

4. The gamma-2CaO.SiO2 composition according to claim 1, which is a cement admixture. ２ Containing fired product.

5. γ-2CaO.SiO according to any one of claims 1 to 4 ２ A method for producing a calcined product containing CaO, SiO ２ A γ-2CaO.SiO2 composite is produced by firing a raw material mixture containing raw materials and waste materials at a firing temperature of 1280°C to 1600°C. ２ Method for producing a fired product containing the compound.

6. The gamma-2CaO.SiO2 composition according to claim 5, wherein the waste is at least one waste selected from coal ash, blast furnace slag, steelmaking slag, concrete sludge, waste concrete, incineration fly ash, and municipal waste incineration ash. ２ Method for producing a fired product containing the compound.

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