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

Abstract

Disclosed is γ-2CaO∙SiO2-containing fired product which is characterized by satisfying the requirements (a) to (c) described below.　(a) The ratio C' / S' (molar ratio) expressed by ([CaO] - 4[Fe2O3]) / [SiO2] is 1.90 to 2.10.　(b) The ratio Fe2O3 / Al2O3 (molar ratio) is 0.90 to 1.10.　(c) Fe2O3 is 20.00 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, slowly cooled blast furnace slag, converter slag, electric furnace slag, etc. have a higher Al content than ordinary cement clinker compositions. 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 In the production of aluminum, there is a high possibility that effective utilization of waste materials will be required. In addition, some waste materials, such as converter slag and electric furnace oxidizing slag, contain aluminum. ２ O ３Not only that, but Fe ２ O ３ There is a lot of waste with high content of mercury, and there is a demand for effective utilization of such waste.

[0005] However, γ-2CaO.SiO ２ In the production of Al ２ O ３ and FeO 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 that contain a large amount of Al. ２ O ３ and FeO ３ When the content is low, the amount of melt required for firing is insufficient, and the firing temperature must be increased, which increases the amount of carbon dioxide emitted from fossil fuels during firing.

[0008] The object of the present invention is to ２ O ３ and Fe ２ O ３ A specified amount of γ-2CaO.SiO can be used as raw material from waste with a high content. ２The 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] In particular, the present invention provides Al ２ O ３ together with FeO ３ When the content of Fe is high (Fe ２ O ３ / Al ２ O ３ (molar ratio) is 0.90 to 1.10), specifically, Al ２ O ３ and FeO ３ reacts with CaO to form 4CaO.Al ２ O ３ Fe ２ O ３ (C ４ AF), CaO and SiO ２ By changing the quantitative relationship (C / S) of these C ４ It was found that the composition can be designed taking into consideration the coexistence of AF.

[0012] That is, the present invention is as follows: [1] A γ-2CaO.SiO2 powder characterized by satisfying the following requirements a) to c): ２ a) {[CaO]-4[Fe ２ O ３ ]} / [SiO ２ The C' / S' (molar ratio) represented by the formula: is 1.90 to 2.10. ２ O ３ / Al ２ O ３ (molar ratio) is 0.90 to 1.10. ２ O ３ is 20.00 mass% or less.

[0013] [2] d) 4CaO・Al ２ O ３ Fe ２ O ３ Mineral composition C shown by ４ The γ-2CaO.SiO according to the above [1], characterized in that AF is more than 5.0 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 material is produced by firing a raw material mixture containing raw materials and waste materials at a firing temperature of 1280°C to 1400°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 converter slag and electric furnace slag. ２ Method for producing a fired product containing the compound.

[0015] According to the present invention, conventional CaO raw materials and SiO ２In 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 and FeO ３の 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 and FeO ３ It has a high content of , making 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 fired product is characterized by satisfying the following requirements a) to c):

[0018] a) {[CaO]-4[Fe ２ O ３ ]} / [SiO ２ The C' / S' (molar ratio) represented by the formula: is 1.90 to 2.10. ２ O ３ / Al ２ O ３ (molar ratio) is 0.90 to 1.10. ２ O ３ is 20.00 mass% or less.

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

[0020] First, CaO, SiO ２ , Al ２ O ３ and Fe２ O ３ When a raw material containing the above is used, the reaction is generally considered to occur in the following order (1) and (2). A schematic diagram of this reaction is shown in FIG. 1.

[0021] (1) Fe ２ O ３ But, Al ２ O ３ and reacts with CaO to form C ４ AF is formed. At this time, b) Fe ２ O ３ / Al ２ O ３ (molar ratio) is 0.90 to 1.10, so Al ２ O ３ is almost entirely consumed. (2) C ４ The remaining CaO after forming AF is SiO ２ reacts with 2CaO.SiO ２ (C ２ S).

[0022] CaO and SiO in (2) 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 The amount of CaO and SiO remaining after this consumption is four times the molar amount of the content. ２ The composition is designed so that the molar ratio 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 7 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 Fe, b) ２ O ３ / Al ２ O ３(molar ratio) is 0.90 to 1.10, and Fe ２ O ３ Al ２ O ３ This is effective when using waste that contains as much Fe as ２ O ３ / Al ２ O ３ is preferably 0.93 to 1.07, and more preferably 0.95 to 1.05.

[0028] The gamma-2CaO.SiO of the present invention ２ In the fired product containing Fe, ２ O ３ is 20.00 mass% or less. ２ O ３ If it exceeds 20.00 mass%, a large amount of C ４ FA is produced, and γ-2CaO.SiO ２ It is not possible to obtain a fired product containing a sufficient amount of Fe. ２ O ３ is preferably 18.00 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 Fe can be obtained. ２ O ３ When the content is high, a sufficient amount of melt is present during firing, and the firing temperature can be lowered to a temperature of 1280°C to 1400°C, thereby reducing the amount of carbon dioxide emitted from fossil fuels during firing.

[0029] The gamma-2CaO.SiO of the present invention ２ In the calcined product containing d) 4CaO.Al ２ O ３ Fe ２ O ３ Mineral composition C shown by ４ It is preferable that the AF content is more than 5.0% by mass. Those satisfying the above requirements a) to c) usually satisfy requirement d). ４ The upper limit of AF is not particularly limited, but γ-2CaO.SiO２ In order to obtain a fired product containing a sufficient amount of , it is preferably 50.0 mass % or less.

[0030] 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.

[0031] The gamma-2CaO.SiO of the present invention 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.

[0032] 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

[0033] 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 and FeO 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 ２A fired product containing a high proportion of

[0034] 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.SiO ２ Carbon dioxide emissions during production can be reduced.

[0035] 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, converter slag, electric 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, converter slag, electric furnace slag, steelmaking slag, non-ferrous slag, coal ash, concrete sludge, waste concrete, sewage sludge, water purification sludge, papermaking 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 O３ Its content is high, and its main components are CaO and SiO ２ , Al ２ O ３ From the viewpoint of the above, it is preferable to use coal ash, blast furnace slag, converter slag, electric furnace slag, concrete sludge, waste concrete, incineration fly ash, and municipal waste incineration ash. ２ O ３ The use of converter slag and electric furnace slag is particularly preferred because they contain a large amount of slag. These waste materials may also be used in combination.

[0036] 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. ２ The composition of the raw materials and waste materials is measured, and the blending ratio of each raw material is calculated from the ratio of each component in these raw materials so as to satisfy the requirements a) to c) of the present invention, and the raw materials are blended in that ratio. ２ O ３ The raw material composition can be adjusted by blending iron-containing sources.

[0037] 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.

[0038] In the present invention, the firing temperature of the raw material mixture after preparation and mixing is preferably 1280 to 1400°C, more preferably 1280 to 1350°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, it is not preferable from the viewpoint of the amount of thermal energy used. In the composition of the present invention, Al ２ O ３and Fe ２ O ３ When a large amount of fluorine-containing cellulose is contained (for example, when the total amount exceeds 5%), a sufficient amount of melt is generated during firing, so that the temperature can be lowered to the low level described above, thereby reducing the amount of carbon dioxide emitted from fossil fuels during firing. The firing time varies depending on the firing temperature, but is generally 0.5 to 10 hours, preferably 1 to 5 hours.

[0039] 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.

[0040] 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).

[0041] The configuration and effects of the present invention will be explained below using examples, but the present invention is not limited to these examples.

[0042] Industrial raw materials and special grade reagent Al ２ O ３ , Fe ２ O ３ The raw material mixture was prepared using the above and fired in an electric furnace at 1250 to 1350°C for 60 minutes to obtain γ-2CaO.SiO of the specified composition. ２ Table 3 shows the chemical composition, mineral composition, and f-CaO content of the obtained fired product.

[0043] 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. ２The mineral composition of the fired material was determined by X-ray diffraction analysis and Rietveld analysis. f-CaO was measured in accordance with the Cement Association Standard Test Method I-01, Quantitative Analysis of Free Calcium Oxide.

[0044]

[0045] (Firing temperature 1250°C) The composition of Comparative Example 1 contains Fe ２ O ３ is more than 20.00 mass% and γ-2CaO.SiO ２ In addition, the firing process has not progressed sufficiently, and the content of f-CaO is very high.

[0046] (Firing temperature: 1300°C) The compositions of Examples 1 to 5 according to the present invention (C' / S' = 1.90 to 2.10) ４ AF is suppressed to 50.0% or less, and γ-2CaO.SiO ２ On the other hand, the composition of Comparative Example 2 has a C' / S' ratio of 1.90 to 2.10, but the content of Fe ２ O ３ is more than 20.00% by mass, and C ４ A large amount of AF is produced, and γ-2CaO.SiO ２ The content is low.

[0047] (Firing temperature: 1350°C) The compositions of Examples 6 to 9 according to the present invention (C' / S' = 1.90 to 2.10) ４ AF is suppressed to 50.0% or less, and γ-2CaO.SiO ２ On the other hand, the compositions of Comparative Examples 3 and 4 have a C' / S' ratio of 1.90 to 2.10, but the content of Fe is high. ２ O ３ is more than 20.00% by mass, and C ４ A large amount of AF is generated, and γ-2CaO.SiO ２ The content is low.

[0048] 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) to c): ２ a) {[CaO]-4[Fe ２ O ３ ]} / [SiO ２ The C' / S' (molar ratio) represented by the formula: is 1.90 to 2.

10. ２ O ３ / Al ２ O ３ (molar ratio) is 0.90 to 1.

10. ２ O ３ is 20.00 mass% or less.

2. d) 4CaO・Al ２ O ３ Fe ２ O ３ Mineral composition C shown by ４ 2. The γ-2CaO.SiO according to claim 1, wherein AF is more than 5.0 mass%. 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 1400°C. ２ Method for producing a fired product containing the compound.

6. The gamma-2CaO.SiO2 according to claim 5, wherein the waste is at least one waste selected from converter slag and electric furnace slag. ２ Method for producing a fired product containing the compound.

Images