Method for producing wollastonite-containing calcined products

Abstract

To provide a wollastonite-containing material useful as a material to be blended in a hydraulic composition such as cement and concrete, using waste such as biomass ash and construction waste soil.SOLUTION: A method of producing a wollastonite-containing fired product, comprises: a raw-material mixing step of mixing a Ca source and a Cl source with a siliceous raw material; and a mineral forming step of firing the mixed raw materials obtained by the raw-material mixing step to form wollastonite (CaSiO3). It is preferable to use a raw material composition including alkali metal in a poorly water soluble state, such as biomass ash and construction waste soil.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a wollastonite-containing material used as a compounding material for cement and the like. [Background technology]

[0002] Wollastonite (CaSiO3), known as a silicate mineral, is used in many fields, including resins, paints, building materials, rubber, and ceramics. In particular, it is useful as a hardening agent in cement-based building materials and carbonated cured concrete because it reacts with carbon dioxide to develop strength, and it is also attracting attention from the perspective of CO2 reduction because carbon dioxide is absorbed / fixed during this process (see Non-Patent Literature 1).

[0003] On the other hand, in recent years, various efforts to promote renewable energy have led to a boom in the construction and operation of biomass power generation facilities. The amount of combustion ash (biomass ash) generated by biomass power generation is also increasing, and it is desirable to recycle this ash as a resource, such as a raw material for cement, similar to the incineration ash generated from municipal waste. Furthermore, it is desirable to effectively utilize and process the soil and sand discharged as a result of construction work. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Hyodo et al., "CO2 Absorption and Fixation of Cement-Based Materials by Carbonation," Taiheiyo Cement Research Report No. 179 (2020), pp. 15-30. [Overview of the project] [Problems that the invention aims to solve]

[0005] Traditionally, there has been limited knowledge regarding technologies for artificially producing silicate minerals using waste materials such as biomass ash and construction-generated soil.

[0006] The object of the present invention is to provide a technology for efficiently producing wollastonite-containing materials, which are useful as materials to be blended into cement and the like, using waste materials such as biomass ash and construction-generated soil. [Means for solving the problem]

[0007] In view of the above issues, the inventors of this invention conducted diligent research and discovered that wollastonite (CaSiO3), a silicate mineral, can be efficiently formed by using waste materials such as biomass ash and construction-generated soil as raw materials, blending them with a Ca source and a Cl source, and then subjecting them to a calcination process. This led to the completion of the present invention.

[0008] In other words, the present invention has the following configuration. [1] A method for producing a wollastonite-containing calcined product, comprising a raw material preparation step of preparing a siliceous raw material with a Ca source and a Cl source, and a mineral formation step of calcining the raw material preparation obtained through the raw material preparation step to form wollastonite (CaSiO3). [2] A method for producing a wollastonite-containing calcined product according to [1] above, wherein the siliceous raw material is a raw material composition containing alkali metal in a poorly water-soluble state. [3] A method for producing a wollastonite-containing calcined product according to [1] above, using a raw material composition containing alkali metals as constituent elements of silicate minerals and / or a raw material composition containing alkali metals embedded in amorphous silica as the siliceous raw material. [4] A method for producing a wollastonite-containing calcined product as described in [1] above, wherein one or more selected from the group consisting of papermaking sludge, paper sludge incineration ash, sewage sludge incineration ash, ready-mix concrete sludge, chlorine bypass dust washing residue, by-product slaked lime, limestone, quicklime, and slaked lime are used as the Ca source. [5] A method for producing a wollastonite-containing calcined product according to [1] above, wherein one or more selected from the group consisting of chlorine-containing combustible waste and inorganic chlorine compounds are used as the Cl source. [6] The method for producing a wollastonite-containing fired product according to [1] above, wherein the water-to-cement ratio of the raw material blend is 0.2 to 1.0, and the Cl source is formulated so that the Cl molar amount of the Cl source relative to the K molar amount contained in the siliceous raw material has a Cl / K ratio of 0.5 to 4. [7] The method for producing a wollastonite-containing fired product according to [1] above, wherein the raw material blend is fired at 900°C to 1,300°C. [8] The method for producing a wollastonite-containing fired product according to [1] above, wherein the fired product obtained through the mineral formation step is further washed with water and / or classified to obtain the wollastonite-containing fired product. [9] The method for producing a wollastonite-containing fired product according to [1] above, wherein the siliceous raw material is pulverized and / or classified in advance before being subjected to the raw material blending step, and then subjected to the raw material blending step.

[10] The method for producing a wollastonite-containing fired product according to [1] above, wherein the raw material blend is pulverized and / or classified in advance before being subjected to the firing step, and then subjected to the firing step.

[11] The method for producing a wollastonite-containing fired product according to [1] above, wherein chlorine is recovered from the exhaust gas discharged during firing in the mineral formation step and reused as the Cl source. [Effect of the Invention]

[0009] According to the present invention, a wollastonite-containing material useful as a material to be blended with cement or the like can be efficiently produced by a process using waste materials such as biomass ash and construction-generated soil as raw materials. [Brief Description of the Drawings]

[0010] [Figure 1] It is a flowchart for explaining one embodiment of the present invention. [Figure 2] It is a flowchart for explaining another embodiment of the present invention. [Figure 3] It is a chart showing the results of the wollastonite production amount and potassium (K) removal rate in the form of a graph for the results of level 1, level 2, level 7, and level 9 (heating temperature is unified at 1,200°C, Cl / K ratio is 2) conducted in Test Example 1. [Figure 4] This chart shows the results of wollastonite production and potassium (K) removal rate for levels 5-8 (water hardness (HM) was standardized at 0.54 and Cl / K ratio at 2) in Test Example 1, as graphed. [Figure 5] This chart shows the results for wollastonite production and potassium (K) removal rate for levels 3, 4, and 7 (heating temperature 1,200°C, water hardness (HM) 0.54) conducted in Test Example 1, as graphs. [Figure 6] This chart shows the results of Test Example 1, specifically for Level 7 and Level 10 (heating temperature of 1,200°C and hydraulic hardness (HM) of 0.54), with graphs illustrating the wollastonite production amount and potassium (K) concentration before and after treatment. [Figure 7] This chart shows the results for levels 1, 5, and 8 (heating temperature 1,000°C, Cl / K ratio 2) and levels 2, 7, and 9 (heating temperature 1,200°C, Cl / K ratio 2) conducted in Test Example 2, with graphs showing the amount of wollastonite produced and the potassium (K) removal rate. [Figure 8] This chart shows the results of wollastonite production and potassium (K) removal rate for levels 5-7 (water hardness (HM) was standardized at 0.54 and Cl / K ratio at 2) as performed in Test Example 2. [Figure 9] This chart shows the results for levels 3-5 (heating temperature 1,000°C, water hardness (HM) 0.54) in Test Example 2, with graphs illustrating the amount of wollastonite produced and the potassium (K) removal rate. [Modes for carrying out the invention]

[0011] Figure 1 shows a flowchart illustrating one embodiment of the present invention. As shown in this embodiment, the present invention involves blending a siliceous raw material with a Ca source and a Cl source, and subjecting the raw material mixture to a calcination treatment to form wollastonite (CaSiO3), known as a silicate mineral, and obtaining a calcined product containing the wollastonite thus formed. The siliceous raw material and the raw material mixture before calcination may optionally be subjected to crushing and / or classification. Furthermore, the calcined product after calcination may optionally be subjected to washing and / or classification to obtain the wollastonite-containing calcined product provided by the present invention. Calcination can be carried out using conventional means as appropriate, such as a batch-type electric furnace, an internally heated or externally heated rotary kiln (in this case, continuous processing is possible). For example, in the case of a rotary kiln, it can also serve as a means for blending the Ca source and the Cl source.

[0012] Figure 2 shows a flowchart illustrating another embodiment of the present invention. In this embodiment, the exhaust gas discharged by calcination contains gasified chlorine, and this chlorine is recovered and reused as a Cl source.

[0013] Specifically, in equipment such as calcination kilns, exhaust gas can be extracted through a predetermined extraction device. This exhaust gas is then passed through a solid-gas separation device such as a cyclone-type air separator or a bag filter to separate it into alkaline dust containing KCl, NaCl, etc., and gas. This gas contains chlorine gas such as HCl and Cl2, along with H2O, CO2, and N2. This is reacted with Ca(OH)2, etc., as an exhaust gas treatment agent to detoxify it into CaClOH, CaCl2, etc., and then passed through a solid-gas separation device such as a cyclone-type air separator or a bag filter again to separate it into powder and gas. The detoxified chlorine is recovered in the resulting powder as CaClOH, CaCl2, etc., and can be reused as a Cl source for blending with siliceous raw materials. In addition, some unreacted Ca(OH)2 may remain in the powder, but this can similarly be used as a Ca source for blending with siliceous raw materials. Furthermore, the alkaline dust generated when extracting gas from equipment such as a calcination kiln and separating it into solid and gaseous forms can be separately washed with water and the residue can be used as a raw material.

[0014] The present invention will be described in further detail below. In this specification, unless otherwise specified, the notation "%" refers to the internal percentage in terms of mass within the total mass. Furthermore, unless otherwise specified, the notation "~" in numerical ranges refers to the range from the above, including the values ​​at both ends.

[0015] [1. Raw materials for firing] <Silicate raw materials> In this specification, "silicic raw material" has the same meaning as it is generally understood by those skilled in the art. That is, any raw material containing an SiO2 source for forming wollastonite (CaSiO3) is acceptable.

[0016] As the silicate raw material, it is preferable to use a raw material composition that contains alkali metals in a poorly water-soluble state. Specifically, examples include raw material compositions that contain alkali metals such as K and Na as constituent elements of silicate minerals, such as alkali feldspar, and raw material compositions that contain alkali metals such as K and Na embedded in amorphous silica, such as potassium glass. More specifically, it may be waste materials such as biomass ash or construction-generated soil. Specifically, construction-generated soil can be obtained from soil, sediment, excavated soil, waste soil, and construction sludge that are generated incidentally at construction sites or work sites. In addition, volcanic-derived materials such as volcanic ash, silica, and clay can also be used. Note that containing alkali metals in a poorly water-soluble state means that they are contained in a state that cannot be removed even by washing the silicate raw material with water.

[0017] The siliceous raw material may be optionally crushed and / or classified to adjust it to a predetermined particle size before use. For example, its Blaine specific surface area may be 1,000 cm². 2 / g~8,000cm 2 It could be / g, 2,000cm 2 / g~5,000cm 2 It may be / g. Such particle size adjustment enhances the reactivity for forming wollastonite (CaSiO3). The grinding means are not particularly limited, and conventional devices such as ball mills can be used. The classification means are not particularly limited, and conventional devices such as centrifugal air classifiers with rotating blades can be used.

[0018] The biomass ash used as a silicate raw material in the present invention will be described in more detail below.

[0019] <Biomass ash> In this specification, "biomass ash" has the same meaning as it is generally understood by those skilled in the art. That is, it is the ash remaining after incineration or combustion of biomass, which consists of organic materials derived from plants and animals (excluding fossil resources). Typical examples include incinerated ash from plants, trees, and bamboo, and incinerated ash from food waste. It may also be combustion ash obtained by burning a mixture of biomass and coal. From the viewpoint of promoting the effective utilization of biomass, the proportion of ash derived from biomass contained in the biomass ash is preferably 50% to 100% by mass, more preferably 60% to 95% by mass, and particularly preferably 70% to 90% by mass.

[0020] As a biomass ash, among the combustion ash of plants, trees, and bamboo, palm kernel shell ash (PKS ash), obtained by using palm kernel shells as fuel, is a particularly suitable example. Palm kernel shells are a by-product of palm oil production and are mainly used in the natural biomass energy industry. Palm kernel shells are a yellowish-brown fibrous material with a low ash content, and their particle size is approximately 5 mm to 40 mm. With a calorific value of approximately 4,000 kcal / kg, their use as fuel for biomass power generation in energy production using renewable resources has been increasing in recent years.

[0021] The method of incinerating or burning biomass is not particularly limited and may include, for example, a method using a stoker-type combustion furnace or a method using a fluidized bed combustion furnace. In particular, in a fluidized bed combustion furnace, limestone is added in the furnace for the purpose of desulfurization, so it contains calcium and sulfur, which are mainly present in the form of gypsum (CaSO4·2H2O) in the biomass ash. When wollastonite (CaSiO3) is formed by calcination, this also acts as a source of Ca. Furthermore, fly ash from a fluidized bed combustion furnace has a fine particle size, making it easy to crush and mix, and it is highly calcinable. Therefore, it is preferable to use fly ash from a fluidized bed combustion furnace as biomass ash. Examples of fluidized bed combustion furnaces include circulating fluidized bed combustion furnaces and pressurized fluidized bed combustion furnaces.

[0022] <Pretreatment of biomass ash> The biomass ash can be obtained from a biomass power generation facility equipped with equipment such as a fluidized bed combustion furnace, and can be used as it is, or can be used after being subjected to pretreatment such as classification or washing as necessary.

[0023] · Classification In the present invention, for the following reasons, it is preferable to classify the raw material biomass ash and use its fine powder.

[0024] In the equipment of a fluidized bed combustion furnace, sand mainly composed of quartz is introduced as a fluidizing medium. Therefore, the biomass ash contains molten and solidified or agglomerated glass, particles derived from sand (relatively coarse particles), and particles derived from the aforementioned limestone or biomass and containing alkali metals and chlorine (relatively fine particles). Thus, in the biomass ash obtained from a biomass power generation facility equipped with equipment such as a fluidized bed combustion furnace, there are peaks on the side with a smaller particle size and a peak on the side with a larger particle size in its particle size distribution. By using an arbitrarily selected particle size as the classification point between them, the biomass ash can be separated and collected into a coarse fraction and a fine fraction.

[0025] Generally, the Blaine specific surface area of biomass ash recovered from equipment such as a fluidized bed combustion furnace is typically, for example, 1,000 cm 2 / g to 4,000 cm 2 / g, more typically 1,500 cm 2 / g to 3,500 cm 2 / g, and even more typically 2,000 cm 2 / g to 3,000 cm 2 / g. When this raw material biomass ash is classified and the fine powder fraction is collected, its Blaine specific surface area is typically, for example, 2,500 cm 2 / g to 7,000 cm 2 / g, more typically 3,000 cm 2 / g to 6,000 cm 2 / g, and even more typically 4,000 cm 2 / g to 5,000 cm 2It is / g. On the other hand, the Blaine specific surface area of ​​the coarse powder remaining after the fine powder has been extracted is typically, for example, 250 cm². 2 / g~2,000cm 2 It is / g, and more typically 500cm 2 / g~1,500cm 2 It is / g, and more typically 750cm 2 / g~1,250cm 2 It is / g.

[0026] The fine powder obtained by classifying the raw material biomass ash contains a relatively large amount of CaO, and has a good balance of Ca and SiO2 sources necessary for the formation of wollastonite (CaSiO3). Furthermore, its high fineness and ease of calcination without the need for grinding allow wollastonite to be produced at relatively low calcination temperatures or short calcination times. On the other hand, it contains relatively high amounts of chlorine and sulfur, but these can be removed by washing with water as described later, or they can be removed by volatilization during calcination depending on their content.

[0027] On the other hand, the coarse powder obtained by classifying the raw material biomass ash has a high silicon content and low chlorine and sulfur content, making it suitable for use as a general cement clinker raw material, especially as a substitute for clay and coal ash. When used as a cement admixture, concrete admixture, or siliceous material in ALC / calcium silicate boards, it is preferable to crush it to increase its reactivity. The coarse powder can also be used as fine aggregate (sand) in concrete, mortar, and carbonated hardened materials without crushing.

[0028] As described above, biomass ash can be recycled more rationally by taking advantage of the characteristics of the components separated by classification. Specifically, the fine powder obtained by classifying the raw biomass ash is suitable for use as a raw material for forming wollastonite by calcination, and the coarse powder obtained by the same classification is suitable for use as a material for hardened bodies made of hydraulic compositions, such as concrete aggregate, concrete admixture, cement mix, and cement clinker raw material. Furthermore, the calcined product obtained by forming wollastonite from the fine powder can be used as a material for hardened bodies made of hydraulic compositions, such as concrete aggregate, concrete admixture, and cement mix, after adjusting the particle size and removing chlorine and sulfur as needed. In this case, using both the material from the fine powder and the material from the coarse powder as materials for a common hardened body increases the resource recovery rate from the raw biomass ash per hardened body produced, making it more efficient. For example, a calcined product obtained from fine powder can be used as a material for a hydraulic composition, and a hardened body can be obtained using this, while coarse powder can be used as aggregate for the hardened body or crushed and used as a mixed material (admixture).

[0029] When classifying raw biomass ash to separate it into fine powder and coarse powder, the classification point can be arbitrarily selected from within the range of preferably 10 μm to 100 μm, more preferably 30 μm to 90 μm, and particularly preferably 38 μm to 75 μm, from the viewpoint of separating the components as described above.

[0030] The classification method can be any method that can classify biomass ash at classification points on the order of μm as described above, and is not particularly limited, but examples include sieves, gravity sedimentation, inertial classifiers, centrifugal classifiers, and gravity classifiers. Among these, cyclone-type air separators, vortex-type centrifugal classifiers, and sieving devices are preferred from the viewpoint of classification accuracy.

[0031] Furthermore, when classification is performed using a wet process, chlorine dissolves in water, so even fine particles with a relatively high chlorine content will have most of the chlorine removed.

[0032] Furthermore, fluidized bed incinerators may be equipped with boilers, air preheaters, high-temperature gas flow paths, and other facilities for recovering settled incinerated ash, such as cyclone-based ash recovery equipment and bag filter-based ash recovery equipment. The particle size of the recovered incinerated ash varies depending on the recovery equipment, and specific biomass ash of a specific particle size can be recovered from specific recovery equipment. Therefore, instead of classifying the raw biomass ash, it may be possible to prepare biomass ash with a desired particle size by appropriately selecting the above equipment to recover the biomass ash.

[0033] ·Washing In any non-limiting embodiment of the present invention, the biomass ash used as a raw material may be subjected to a water washing treatment before use. This water washing treatment can remove components such as chlorine, sulfur, and potassium, which are undesirable as materials to be incorporated into hydraulic compositions such as cement and concrete.

[0034] The method of washing is not particularly limited and any conventional method may be used. For example, the method of treating biomass ash described in International Publication No. 2021 / 193668 may be referred to as appropriate, as described below. However, it goes without saying that the method of washing is not limited to the specific examples described below.

[0035] The processing method includes, for example, a slurrying step of adding water to biomass ash to form a slurry, a washing step of washing the slurry with water, and a dewatering step of dewatering the slurry after washing. Slurrying can be performed using a powder dissolution tank that has at least a container for holding biomass ash and water, and a stirring means for mixing them to form a slurry. Washing is performed by letting the slurry stand or stirring for a predetermined time. This results in a slurry in which the soluble components of the biomass ash have dissolved into the liquid phase of the slurry. The slurry in this state is discharged from the powder dissolution tank and dewatered using a solid-liquid separation device such as a filter press.

[0036] In the slurrying process described above, the mass ratio (W1 / M1) of biomass ash (M1) to water (W1) is preferably 4 to 10, more preferably 4 to 7, and particularly preferably 4 to 5. If the mass ratio (W1 / M1) is less than 4, the elution of cement-repellent components such as chlorine from the biomass ash may be insufficient, resulting in an insufficient modification effect. Conversely, if the mass ratio (W1 / M1) is greater than 10, the amount of wastewater will be excessive.

[0037] The washing process should preferably take 30 minutes or more, and more preferably 45 minutes or more, to allow the biomass ash to be thoroughly treated with water. Furthermore, while higher temperatures improve the efficiency of leaching repellent components such as chlorine from the biomass ash, from the viewpoint of treatment costs, a temperature of 5°C to 50°C is preferable, and more preferably 25°C to 50°C.

[0038] In the dewatering process, to prevent undesirable components such as chlorine contained in the slurry from remaining with the liquid phase, the moisture content of the dewatered material is preferably 20% to 90% by mass, and more preferably 30% to 70% by mass. Furthermore, if necessary, water is added to the dewatered material and dewatered again. This is more preferable because it almost completely replaces the liquid phase of the slurry with water.

[0039] In the above processing method, it is preferable to adjust the pH during rinsing from strongly alkaline to weakly alkaline to acidic. That is, by lowering the pH, chlorine can be removed more efficiently compared to when the pH is not adjusted. There are no particular restrictions on the pH adjusting agent as long as it can lower the pH of the slurry. Examples include acid solutions and CO2-containing gases. For example, since the combustion exhaust gas of rotary kilns in cement manufacturing facilities, biomass incineration facilities, and biomass power plants contains carbon dioxide (CO2), the pH can be reduced to weakly alkaline by blowing this combustion exhaust gas into the slurry. Any CO2-containing gas will suffice, but to promote efficient carbonation, a carbon dioxide concentration of 10% by volume or more is preferable, and 20% by volume is more preferable. Furthermore, among combustion exhaust gases, the gas after chlorine bypass dust collection in cement manufacturing facilities in particular contains harmful gases such as sulfur oxides (SOx), so the effect of immobilizing these gases can also be expected.

[0040] The pH conditions for washing the slurry are preferably between 4 and 12.5, and more preferably between 5 and 12.

[0041] ·Dried ash In any non-limiting embodiment of the present invention, dry ash may be used as the raw material biomass ash. Dry ash refers to ash that has never been sprayed with water, is not granular, and has not produced hydrates. In contrast, if water is sprayed on the ash, it becomes granular, or chlorine is incorporated into the hydrates produced, it may become difficult to separate characteristic components by classification or washing as described above. Therefore, when using dry ash as the raw material biomass ash and performing washing along with the classification process described above, it is preferable to perform the classification process before the washing process to obtain, for example, fine powder, and then wash it with water.

[0042] Preferably, the dried ash is free from the detection of hydrated Friedel salts or ettringite by powder X-ray diffraction, for example. Furthermore, the moisture content is preferably 10% or less, and more preferably 5% or less. Additionally, the ignition loss is preferably 10% or less. Here, the moisture content can be determined as the mass loss rate when dried at 105°C. The ignition loss can be determined as the mass loss rate when the object dried at 105°C is heated at 975°C.

[0043] <Compositional characteristics of biomass ash> The following describes the typical compositional characteristics of biomass ash, which is considered a silicate raw material, although this description is not limited to these examples.

[0044] The proportion of CaO in the biomass ash used as a silicate raw material (based on ignition raw material) is preferably 10% to 40% by mass, more preferably 15% to 35% by mass. If the proportion of CaO is within the above range, the amount of Ca source required for the formation of wollastonite (CaSiO3) will be reduced, or it will not be necessary after classification, thus keeping the additional equipment for addition and the cost of chemicals used for addition low.

[0045] The silicic acid content (SM) of the biomass ash used as a silicic raw material is preferably 3.0 to 20.0, more preferably 4.0 to 18.0, even more preferably 5.0 to 16.0, and particularly preferably 8.0 to 13.0. If the silicic acid content (SM) is within the above range, the total amount of Al2O3 and Fe2O3 relative to SiO2 can be kept low, so the amount of wollastonite produced can be increased. Therefore, when the calcined material is used as a material for a hydraulic composition, its strength development can be further improved. Here, the silicic acid content (SM) is the ratio of the total amount of Al2O3 and Fe2O3 to the amount of SiO2.

[0046] The proportion of Al2O3 in biomass ash, which is used as a siliceous raw material (based on ignition raw material), is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 3% by mass or less. If the proportion of Al2O3 exceeds the above range, a large amount of unreactive melilite may be produced during calcination. Biomass ash is preferable because it has a lower proportion of Al2O3 compared to general coal ash.

[0047] The amorphous mass (amount of amorphous material) in the biomass ash used as a siliceous raw material is preferably 30% by mass or more, more preferably 35% by mass or more, and particularly preferably 40% by mass or more, from the viewpoint of the rate of wollastonite formation.

[0048] The proportion of alkali metals in biomass ash, which is used as a silicate raw material (based on ignition raw material), is preferably 1.0% to 5.0% by mass, and more preferably 1.5% to 4.0% by mass, in terms of oxide (R2O). If the proportion of alkali metals is below the above range, the rate of wollastonite formation may be slow. On the other hand, if the proportion of alkali metals exceeds the above range, a large amount of unreactive feldspar may be formed during the calcination process, or it may melt during calcination, or large chunks may be generated, making calcination in the kiln difficult. In addition, when the calcined material is used as a cement admixture, concrete admixture, or concrete aggregate, alkali-aggregate reaction may occur.

[0049] The proportion of alkali metal (R) oxides (R2O) can be calculated from the respective proportions (mass%) of Na2O and K2O in the sample using the following formula (1). R2O = Na2O + 0.658K2O ... (1)

[0050] <Ingredients for firing> In this invention, the above-mentioned siliceous raw material is combined with a Ca source and a Cl source to form a raw material mixture for firing. The raw materials may be added to a stirring and mixing tank in a batch manner and stirred and mixed, or, if a firing kiln or similar apparatus is used, the raw materials can be added continuously, and the mixing and firing processes can be carried out in the same apparatus.

[0051] As a source of calcium, preferred examples include waste materials such as paper milling sludge, paper sludge incineration ash, sewage sludge incineration ash, ready-mix concrete sludge, chlorine bypass dust washing residue, and by-product slaked lime. Industrial raw materials such as limestone, quicklime, and slaked lime may also be used. These may be used individually or in combination of two or more.

[0052] Furthermore, as a source of chlorine, chlorine-containing combustible waste such as waste plastics (e.g., polyvinyl chloride) is a preferred example. Industrial raw materials such as inorganic chlorine compounds (CaCl2, MgCl2) may also be used. These may be used individually or in combination of two or more.

[0053] Other ingredients Other siliceous raw materials that can be used as an SiO2 source include, for example, construction waste soil (soil, sand, excavated soil, waste soil, and construction sludge generated as by-products at construction sites and other work sites), volcanic ash and other volcanic-derived materials, silica, and clay. These may be used individually or in combination of two or more. Alternatively, in some cases, these construction waste soils may be used alone without incorporating the biomass ash mentioned above.

[0054] Other raw materials that can be used as a source of calcium include, for example, limestone, quicklime, slaked lime, seashells, and industrial or general waste containing calcium. Examples of industrial waste containing calcium include ready-mix concrete sludge, various types of sludge (e.g., sewage sludge, water treatment sludge, steelmaking sludge, etc.), construction waste, concrete waste, various types of incineration ash (e.g., biomass ash, coal ash, chicken manure ash, livestock manure ash, sludge incineration ash), foundry sand, rock wool, waste glass, blast furnace secondary ash, various by-products, and unused resources (materials remaining without being used, etc.). Examples of general waste containing calcium include dry sewage sludge powder and municipal solid waste incineration ash. These may be used individually or in combination of two or more types.

[0055] The calcination raw material mixture may appropriately contain common raw materials used in the manufacture of cement clinker, to the extent that they do not impair the effects of the present invention. Examples include aluminum-containing raw materials such as clay (Al2O3 source), and iron-containing raw materials such as iron slag and iron cake (Fe2O3 source).

[0056] The calcination raw material mixture can be prepared by mixing the aforementioned biomass ash, Ca source, SiO2 source, and other raw materials in appropriate amounts. The raw materials may also be crushed as needed. The means of mixing the raw materials are not particularly limited; for example, conventional equipment such as a mixer may be used. For crushing, conventional equipment such as a ball mill may be used.

[0057] <Compositional characteristics of the raw material mixture for firing> The following describes typical compositional characteristics of raw material formulations for calcination, although these are not limited to those listed above.

[0058] The hydraulic coefficient (HM) of the calcination raw material mixture is preferably 0.2 to 1.0, more preferably 0.3 to 0.8, and even more preferably 0.5 to 0.7. If the hydraulic coefficient (HM) is within the above range, the Ca source necessary for the formation of wollastonite can be secured, thereby increasing the amount of wollastonite produced. Furthermore, when the calcined material is used as a material for a hydraulic composition, its strength development can be further improved. Here, the hydraulic coefficient (HM) is the ratio of the amount of CaO to the total amount of SiO2, Al2O3, and Fe2O3.

[0059] For the calcination raw material formulation, it is preferable to prepare the above-mentioned Cl source such that the amount of Cl molars relative to the amount of K molars contained in the siliceous raw material is a Cl / K ratio of 0.5 to 4. The Cl / K ratio is preferably 1 to 3, more preferably 2 to 3. If the Cl / K ratio is within the above range, alkali metals contained in the siliceous raw material in a poorly water-soluble state can be removed, and in the process, a readily reactive SiO2 source can be generated, thereby increasing the amount of wollastonite produced. On the other hand, if the Cl / K ratio exceeds the above range, an excess of chlorine will be introduced into the system, which may result in disadvantages such as chlorine remaining as a solid solution in the calcined product, excessive generation of chlorine gas causing corrosion of equipment, increased chlorine gas treatment costs, and excessive generation of low-melting-point deposits inside the equipment causing blockage.

[0060] The calcination raw material mixture may be optionally crushed and / or classified to adjust to a predetermined particle size before use. For example, its Blaine specific surface area may be 1,000 cm². 2 / g~8,000cm 2 It could be / g, 2,000cm 2 / g~5,000cm 2 It may be / g. Such particle size adjustment enhances the reactivity for forming wollastonite (CaSiO3). The grinding means are not particularly limited, and conventional devices such as ball mills can be used. The classification means are not particularly limited, and conventional devices such as centrifugal air classifiers with rotating blades can be used.

[0061] Furthermore, the mass ratio of CaO to SiO2 (CaO / SiO2) in the calcination raw material mixture is preferably 0.5 to 1.2, more preferably 0.5 to 1.1, even more preferably 0.6 to 1.0, and particularly preferably 0.7 to 0.9, from the viewpoint of the amount of wollastonite produced.

[0062] The silica content (SM) of the calcination raw material mixture is preferably 3.0 to 20.0, more preferably 4.0 to 19.0, even more preferably 5.0 to 18.0, even more preferably 8.0 to 17.0, particularly preferably 10.0 to 17.0, and most preferably 12.0 to 17.0. If the silica content (SM) is within the above range, the total amount of Al2O3 and Fe2O3 relative to SiO2 can be kept low, so the amount of wollastonite produced can be increased. Therefore, when the calcined material is used as a material for a hydraulic composition, its strength development can be further improved.

[0063] The proportion of Al2O3 in the calcination raw material formulation (based on ignition raw materials) is preferably 1.0% to 7.0% by mass, more preferably 1.5% to 5.0% by mass, and particularly preferably 2.0% to 3.0% by mass. If the proportion of Al2O3 is within the above range, the amount of wollastonite produced can be increased. However, if the proportion of Al2O3 exceeds the above range, a large amount of unreactive melilite may be produced during calcination.

[0064] The proportion of alkali metals in the calcination raw material mixture (based on ignition raw materials) is preferably 0.3% to 4.0% by mass, more preferably 1.1% to 3.0% by mass, and particularly preferably 1.2% to 2.5% by mass, in terms of oxide (R2O). If the proportion of alkali metals is below the above range, the rate of wollastonite formation may be slow. On the other hand, if the proportion of alkali metals exceeds the above range, a large amount of unreactive feldspar may be formed during the calcination process, or it may melt during calcination, or large lumps may be generated, making calcination in the kiln difficult. Furthermore, when the calcined material is used as a cement admixture, concrete admixture, or concrete aggregate, alkali-aggregate reaction may occur.

[0065] The proportion of alkali metals (R) converted to oxides (R2O) can be calculated using the formula (1) described above. Furthermore, if the proportion of alkali metals (R2O) in the calcination raw material mixture is high, or if it is desired to reduce the alkali metal content in the calcined product, chlorine may be added and the calcination process described later may be carried out to chlorinate the alkali metals, which can then be removed by volatilization or washing of the product with water.

[0066] [2. Firing] In the present invention, a calcined product containing wollastonite (CaSiO3), known as a silicate mineral, is obtained by subjecting the raw material mixture prepared as described above to a calcination treatment.

[0067] <Firing process> The firing process is not particularly limited, as long as it can form wollastonite, but it can preferably be carried out at a temperature of 900°C to 1300°C, more preferably 1000°C to 1250°C, and even more preferably 1100°C to 1200°C.

[0068] The firing method is not particularly limited, and conventional equipment such as a rotary kiln can be used. When firing using a rotary kiln, waste materials such as waste oil, waste tires, and waste plastics may be used as fuel substitutes.

[0069] <Wollastonite-containing calcined material> The calcined product after the above-mentioned firing process contains wollastonite (CaSiO3), which is known as a silicate mineral. Wollastonite is known to exist in the forms of wollastonite (α-type, low-temperature type) and pseudowollastonite (β-type, high-temperature type). The wollastonite-containing calcined product provided by the present invention may contain only one of these forms, or it may contain a combination of multiple forms. The wollastonite content (total if multiple forms are included in combination) is preferably 10% by mass or more, more preferably 20% by mass or more, and particularly preferably 30% by mass or more. The pseudowollastonite (β-type, high-temperature type) form has higher carbon dioxide absorption activity. Therefore, when the wollastonite-containing calcined product provided by the present invention is used for the purpose of carbon dioxide absorption, it is preferable that the pseudowollastonite form accounts for a large proportion of the wollastonite, and more preferably, for example, that it accounts for more than half of the wollastonite form.

[0070] The calcined product after the above-mentioned firing process may contain other mineral components besides wollastonite. For example, lanquinite (3CaO·2SiO2) is one such component. Lanquinite is reactive with carbon dioxide and exhibits strength development through this reaction. However, from the viewpoint of ensuring wollastonite content, the lanquinite content in the wollastonite-containing calcined product provided by the present invention is preferably 20% by mass or less, and more preferably 10% by mass or less. Merilites are another example. These include okermanite components (Ca2MgSi2O7), ferrookermanite components (Ca2FeSi2O7), gehlenite components (Ca2Al2SiO7), sodamerylite components (CaNaAlSi2O7), hardistonite components (Ca2ZnSi2O7), gougiaite components (Ca2BeSi2O7), Okayamaite components (Ca2B2SiO7), ferrighehlenite components (Ca2Fe3+2SiO7), and ferrialumineghehlenite components (Ca2Fe3+AlSiO7). Here, melilites have poor reactivity with carbon dioxide and therefore do not exhibit strong strength development through this reaction. For this reason, in the wollastonite-containing calcined product provided by the present invention, the melilite content is preferably 20% by mass or less, and more preferably 10% by mass or less.

[0071] The calcined product after the above-mentioned firing may contain lanite (2CaO·SiO2) as an intermediate reaction mineral component. Alternatively, it may contain quicklime, quartz, feldspar, amorphous phase, etc., as unreacted mineral components. Here, from the viewpoint of ensuring wollastonite content, in the wollastonite-containing calcined product provided by the present invention, the quicklime content is preferably 8% by mass or less, the quartz content is preferably 40% by mass or less, and the feldspar content is preferably 30% by mass or less. Furthermore, the amorphous mass is preferably 45% by mass or less, more preferably 35% by mass or less, and most preferably 25% by mass or less.

[0072] In this specification, "mineral" includes not only minerals formed as natural products geologically, but also artificial minerals that have a similar chemical composition and crystal structure to natural minerals, formed by processes such as the calcination described above. The morphology of mineral components can be measured according to conventional methods, such as powder X-ray diffraction, microscopic observation, and electron backscatter diffraction (EBSD). Furthermore, the mineral content can be measured by the Rietveld method in the case of powder X-ray diffraction, or by point counting in the case of microscopic observation or electron backscatter diffraction.

[0073] <Post-processing of fired products> The calcined product obtained by the above calcination process can be used as is for various purposes as described later. Alternatively, if necessary, post-processing such as washing and classification may be performed, and the resulting product may be the wollastonite-containing calcined product provided by the present invention. In this case, multiple post-processing treatments may be performed in combination. For example, the product may be washed and then classified to adjust to a predetermined particle size, or the product with a predetermined particle size after classification may be subjected to further washing.

[0074] ·Washing Water washing can remove components that are undesirable as materials to be incorporated into hydraulic compositions such as cement and concrete, such as chlorine, sulfur, and potassium. In particular, in the present invention, chlorine added as a Cl source and readily water-soluble alkali metals (KCl, NaCl) may remain in the calcined product after the above-mentioned calcination without volatilizing, so these can be effectively removed by water washing. There are no particular restrictions on the means of water washing, and it can be carried out using well-known means such as a powder dissolution tank for mixing powder and water, similar to the pretreatment of biomass ash described above. For example, the powder can be mixed with water and left to stand or stirred for a predetermined time, thereby dissolving the soluble components into the liquid phase of the slurry, and then discharged from the powder dissolution tank and dewatered using a solid-liquid separation device such as a filter press.

[0075] ·Classification Classification allows for the removal of components undesirable for use in hydraulic compositions such as cement and concrete, such as sulfur and alkali, which are unevenly distributed in the dust recovered as fine powder. Furthermore, since the dust recovered as fine powder also contains wollastonite-containing calcined material, by subjecting only the dust recovered as fine powder to water washing, readily water-soluble alkali metals can be removed (treated), and the residue after water washing can be used as calcined product. This significantly reduces the amount of calcined product subjected to water washing and also reduces the amount of undesirable components in the calcined product. There are no particular restrictions on the means of classification, and examples include sieving, gravity sedimentation, inertial classifiers, centrifugal classifiers, and gravity classifiers, similar to the pretreatment of biomass ash described above. Among these, cyclone-type air separators, vortex-type centrifugal classifiers, and sieving devices are preferred from the viewpoint of classification accuracy.

[0076] [3. Uses of fired products] The wollastonite-containing calcined material provided by the present invention can be used as civil engineering material such as roadbed material and backfill material after adjusting the particle size, such as by crushing, as needed. Alternatively, it can be used as aggregate for mortar and concrete. In other words, while sand is usually used as fine aggregate and gravel as coarse aggregate, this material can be used as a substitute for them.

[0077] The wollastonite-containing calcined product provided by the present invention can also be used as a filler for resin reinforcement, a cement admixture, a concrete admixture, and a siliceous material for ALC / calcium silicate boards. In this case, it is preferable to crush or classify the material as needed to adjust the particle size appropriately. For example, the Blaine specific surface area is preferably 2,500 cm². 2 / g~10,000cm 2 / g, more preferably 3,000cm 2 / g~9,000cm 2The weight is / g. During the grinding process, conventional gypsum or grinding aids may be added. The grinding method is not particularly limited, and conventional devices such as ball mills can be used. The classification method is not particularly limited, and conventional devices such as centrifugal air classifiers with rotating blades can be used.

[0078] When the wollastonite-containing calcined product provided by the present invention is used as a cement mixer, concrete admixture, etc., after adjusting the particle size as described above, effects such as reduced bleeding, improved fluidity, and reduced heat of hydration can be expected when it is mixed with water and hardened.

[0079] Furthermore, by adjusting the particle size of the wollastonite-containing calcined material provided by the present invention as described above, and then mixing it with existing cements such as rapid-hardening Portland cement, rapid-hardening Portland cement clinker, C3A-high content cement (e.g., C3A content of 10% to 15% by mass), or C3A-high content cement clinker (e.g., C3A content of 10% to 15% by mass), in an amount of 5 to 25 parts by mass per 100 parts by mass of cement, cement of equivalent quality to ordinary Portland cement can be obtained.

[0080] The wollastonite-containing calcined product provided by the present invention, compared to conventional cements such as Portland cement, for example, can use less limestone as a raw material and can be manufactured at a lower calcination temperature. Therefore, as described later, by using it as a material for hydraulic compositions instead of cement, the overall carbon dioxide emissions related to cement production can be reduced.

[0081] <Hydraulic composition> As described above, the wollastonite-containing calcined product provided by the present invention can be used as a material for hydraulic compositions such as cement, mortar, and concrete. Here, in this specification, "hydraulic composition" has the same meaning as it is usually understood by those skilled in the art. That is, it is a composition that hardens when mixed with water. Typically, such compositions are prepared in powder form before being mixed with water.

[0082] When using the wollastonite-containing calcined material provided by the present invention as a material for a hydraulic composition, it is preferable to adjust the particle size appropriately by crushing or classifying it as needed. For example, the Blaine specific surface area is preferably 2,500 cm². 2 / g~10,000cm 2 / g, more preferably 3,000cm 2 / g~9,000cm 2 The value is / g. The above Brain specific surface area is 2,500 cm². 2 If the amount is greater than or equal to / g, the strength of the resulting cured material will be greater. On the other hand, if the Blaine specific surface area is 10,000 cm² 2 If the value is less than / g, the energy required for grinding can be kept lower from a manufacturing cost perspective.

[0083] The grinding means are not particularly limited, and conventional devices such as ball mills can be used. The classification means are not particularly limited, and conventional devices such as centrifugal air classifiers with rotating blades can be used.

[0084] ·cement When the wollastonite-containing calcined product provided by the present invention is used as a material for a hydraulic composition, it is preferable that the hydraulic composition contains conventional cement from the viewpoint of increasing the strength of the resulting hardened body. Such cement is not particularly limited and examples include various Portland cements such as ordinary Portland cement, rapid-hardening Portland cement, moderate-heat Portland cement, and low-heat Portland cement, as well as eco-cement, fast-hardening cement, and ultra-fast-hardening cement. These may be used individually or in combination of two or more. Among these, at least one of ordinary Portland cement and rapid-hardening Portland cement is preferred from the viewpoint of strength development and cost. When the wollastonite-containing calcined product is used as a material for a hydraulic composition, for example, in 100 parts by mass of the cement composition, it may be 5 to 50 parts by mass, 10 to 35 parts by mass, or 15 to 25 parts by mass. Furthermore, when producing a carbonated hardened body from a hydraulic composition, the proportion of the above-mentioned calcined material contained in the hydraulic composition may, from the viewpoint of increasing the amount of carbon dioxide absorbed and increasing the strength of the resulting hardened body, be set at a lower limit of, for example, 20 parts by mass or more, 30 parts by mass or more, 50 parts by mass or more, or 75 parts by mass or more, in 100 parts by mass of the cement composition. On the other hand, from the viewpoint of increasing the strength of the hardened body when demolding is performed, or performing demolding earlier, and thereby improving the production efficiency of products made from the hardened body, the upper limit of the above proportion may, for example, 95 parts by mass or less, 90 parts by mass or less, more preferably 75 parts by mass or less, 60 parts by mass or less, or 50 parts by mass or less, in 100 parts by mass of the cement composition.

[0085] Furthermore, the above-mentioned hydraulic composition may be in a form that does not contain conventional cement, and for example, the wollastonite-containing calcined product provided by the present invention may be used as is. That is, for example, the hydraulic composition may contain 100% by mass of the wollastonite-containing calcined product provided by the present invention. However, when used in a form that does not contain conventional cement or contains only a small amount thereof, from the viewpoint of strength development, the Blaine specific surface area should be increased, for example, to 8,000 cm². 2 / g~12,000cm 2 It is preferable to perform at least one of the following: grinding the material to a weight of / g, or heating and curing it when mixing it with water and kneading it to harden.

[0086] ·plaster The above-mentioned hydraulic composition may contain gypsum as an ingredient, from the viewpoint of fluidity and workability of the mixture before hardening. The gypsum is not particularly limited and examples include natural dihydrate gypsum, flue gas desulfurization gypsum, phosphate gypsum, titanium gypsum, and hydrofluoric acid gypsum. Examples of gypsum forms include dihydrate gypsum, hemihydrate gypsum, and anhydrous gypsum. These may be used individually or in combination of two or more types.

[0087] The amount of gypsum to be added is preferably 1 to 6 parts by mass, more preferably 3 to 5 parts by mass, per 100 parts by mass of the hydraulic composition (powder), from the viewpoint of the fluidity and workability of the mixture before hardening.

[0088] Furthermore, while gypsum powder that has been pre-ground may be used as the gypsum to be incorporated into the above-mentioned hydraulic composition, when the wollastonite-containing calcined product provided by the present invention is ground to an appropriate particle size, the gypsum may also be ground together so that the gypsum is included in the above-mentioned hydraulic composition.

[0089] • Amines The above-mentioned hydraulic composition may contain amines as an ingredient. Amines are known to react with carbon dioxide to promote the generation of carbonate ions, and when the hydraulic composition contains amines, the carbonation of the calcium component contained in the hydraulic composition proceeds more efficiently, thereby increasing the strength of the carbonated hardened product described later.

[0090] The amines used can be any amine having an amino group and a hydroxyl group in their molecule, and are not particularly limited. Examples include monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), diglycolamine (DGA), diisopropanolamine (DIPA), methyldiethanolamine (MDEA), and triisopropanolamine (TIPA). These amines are generally known as grinding aids. Alternatively, waste liquid containing used amines recovered from amine-based carbon dioxide recovery equipment used to recover carbon dioxide from exhaust gases of factories, etc., may be used as the amines. In other words, such used amines are usually disposed of as waste liquid, but they can be effectively reused by using them as the amines mentioned above.

[0091] The amount of amines added is preferably 0.002 parts by mass to 1 part by mass, more preferably 0.01 parts by mass to 0.1 parts by mass, per 100 parts by mass of the hydraulic composition (powder), from the viewpoint of accelerating the carbonation of the hardened body or, for example, enhancing its strength development when carbonation curing is performed.

[0092] Furthermore, the amines may be used as grinding aids when grinding the wollastonite-containing calcined product provided by the present invention to an appropriate particle size, so that the amines are included in the hydraulic composition.

[0093] Other materials Other materials may be added to the above hydraulic composition as appropriate and as needed. Examples of other materials include various additives such as water-reducing agents, defoaming agents, and shrinkage-reducing agents, as well as various admixtures such as fly ash, silica fume, blast furnace slag powder, and limestone powder. In addition, hardening agents and hardening accelerators may be added to increase initial strength and improve handling. The proportion of other materials in the above hydraulic composition varies depending on the type of material, but is typically, for example, 20% by mass or less, preferably 10% by mass or less.

[0094] • Gypsum and free lime content The gypsum content in the above hydraulic composition is preferably 5.0% by mass or less, and more preferably 1.0% to 4.0% by mass, in terms of SO3. When the gypsum content is within the above range, the fluidity of the mixture before hardening is further improved.

[0095] The proportion of free lime in the above hydraulic composition is preferably 2.0% by mass or less, and more preferably 0.2 to 1.5% by mass, from the viewpoint of strength development in the carbonation curing process described later.

[0096] Furthermore, if the hydraulic composition described above is made by blending materials other than the wollastonite-containing calcined product provided by the present invention, the gypsum and free lime content described above shall include gypsum and free lime derived from those materials.

[0097] <Cured body> By mixing the above hydraulic composition with water and kneading it to harden it, a hardened body using a wollastonite-containing calcined product can be obtained.

[0098] ·water The water used to obtain the hardened body is not particularly limited, and examples include tap water and sludge water. The mass ratio of water to the hydraulic composition (powdered) (water / powdered hydraulic material) is preferably 0.3 to 1.0, more preferably 0.4 to 0.7. If the above ratio is 0.3 or higher, permeability is ensured and the carbon dioxide absorption effect is greater. In addition, the workability of the kneaded hydraulic composition is improved. If the above ratio is 1.0 or lower, the strength of the hardened body can be ensured.

[0099] ·aggregate When hardening the above hydraulic composition, aggregate may be used to form the body of the resulting hardened material. Examples of fine aggregates include river sand, mountain sand, land sand, sea sand, crushed sand, silica sand, slag, lightweight fine aggregate, recycled aggregate, artificially calcined aggregate, or mixtures thereof. Examples of coarse aggregates include river gravel, mountain gravel, land gravel, crushed stone, slag, lightweight coarse aggregate, recycled aggregate, artificially calcined aggregate, or mixtures thereof.

[0100] When hardening the above-mentioned hydraulic composition, the aggregate used may be a wollastonite-containing calcined product provided by the present invention (hereinafter, when the wollastonite-containing calcined product provided by the present invention is used as the aggregate, it may be referred to as "calcined aggregate"). In this case, the majority of the surface of the calcined aggregate contains wollastonite, and the carbonation of wollastonite can increase the total amount of carbon dioxide absorbed into the hardened body. Furthermore, the interface between the cement paste and the aggregate becomes denser due to the carbonation reaction, thereby increasing the strength of the hardened body.

[0101] When the above-mentioned calcined aggregate is used in the above-mentioned hydraulic composition, it can be used as at least one of either fine aggregate or coarse aggregate. In this case, the wollastonite-containing calcined material provided by the present invention may be crushed or its particle size adjusted as appropriate to achieve a particle size suitable for use as a desired aggregate (fine aggregate or coarse aggregate, etc.), and the calcined aggregate prepared in this manner may be used.

[0102] When the above-mentioned calcined aggregate is used in the above-mentioned hydraulic composition, for example, if the hardened body of the hydraulic composition is similar to conventional mortar, it may be included as a substitute for the fine aggregate normally used in such mortar, or if the hardened body of the hydraulic composition is similar to conventional concrete, it may be included as a substitute for at least one of the fine aggregate and coarse aggregate normally used in such concrete. However, from the viewpoint of increasing the total amount of carbon dioxide absorbed by the hardened body, it is preferable that it be included as a substitute for the fine aggregate normally used.

[0103] When using the above-mentioned calcined aggregate in the hydraulic composition, other aggregates may be used in addition to the calcined aggregate. As mentioned above, examples of fine aggregates include river sand, mountain sand, land sand, sea sand, crushed sand, silica sand, slag, lightweight fine aggregate, recycled aggregate, artificially calcined aggregate, or mixtures thereof. Examples of coarse aggregates include river gravel, mountain gravel, land gravel, crushed stone, slag, lightweight coarse aggregate, recycled aggregate, artificially calcined aggregate, or mixtures thereof.

[0104] When using the above-mentioned calcined aggregate in the above-mentioned hydraulic composition, the proportion of the calcined aggregate in the total amount of aggregate used is preferably, as a lower limit, 20% by mass or more, 25% by mass or more, 30% by mass or more, 50% by mass or more, 70% by mass or more, 90% by mass or more, or 100% by mass. If the proportion of the calcined aggregate in the total amount of aggregate used is within or above the above range, the total amount of carbon dioxide that can be absorbed by the resulting hardened body can be increased compared to when general aggregate is used, and the strength of the resulting hardened body can be increased.

[0105] Furthermore, when the above-mentioned fired aggregate is fine aggregate, the proportion of the above-mentioned fired aggregate in the total amount of fine aggregate is preferably, as a lower limit, 20% by mass or more, 25% by mass or more, 30% by mass or more, 50% by mass or more, 70% by mass or more, 90% by mass or more, or 100% by mass. If the proportion of the above-mentioned fired aggregate in the total amount of fine aggregate used is within or above the above range, the total amount of carbon dioxide that can be absorbed by the resulting hardened body can be increased compared to when general aggregate is used, and the strength of the resulting hardened body can be increased.

[0106] When aggregate is used in the above hydraulic composition, the amount of aggregate (total amount if fine aggregate and coarse aggregate are used in combination) is preferably 200 to 700 parts by mass, more preferably 200 to 600 parts by mass, per 100 parts by mass of the hydraulic composition (powder). If the amount of aggregate is within the above range, the strength of the resulting hardened body will be good, while the shrinkage rate will be kept low.

[0107] When fine aggregate and coarse aggregate are used in combination in the above hydraulic composition, the fine aggregate ratio (percentage of the mass of fine aggregate to the total amount of aggregate) is preferably 5% to 60%. If the fine aggregate ratio is within the above range, the workability and ease of molding of the mixture will be improved. The coarse particle ratio is preferably 1.0 to 7.0, more preferably 1.5 to 6.5.

[0108] <Carbonated hardened material> By mixing and kneading the above hydraulic composition with water and allowing it to harden, a hardened body using a wollastonite-containing calcined product can be obtained. Furthermore, by subjecting it to a carbonation treatment during hardening, a carbonated hardened body that has absorbed carbon dioxide can be obtained. Herein, in this specification, "carbonation" refers to the reaction of an alkaline component in the hardened body made from the above hydraulic composition with carbon dioxide, thereby lowering the pH of the alkaline component.

[0109] The following describes, as an example, a method for obtaining a carbonated hardened body by mixing (A) a hydraulic composition (in powder form), (B) water, and (C) aggregate to prepare a mixture of the hydraulic composition, casting it into a formwork, and curing it.

[0110] [Preparation process for kneaded products] This process involves mixing the above-mentioned (A) hydraulic composition (in powder form), (B) water, and (C) aggregate to prepare a compound.

[0111] The method of mixing each ingredient is not particularly limited. Furthermore, the equipment used for mixing is also not particularly limited; for example, conventional mixers such as omni mixers, pan mixers, twin-shaft mixers, and tilting-drum mixers can be used.

[0112] [Concrete pouring process] This step involves pouring the mixture obtained in the above step into a formwork.

[0113] The concrete placement method is not particularly limited, and conventional methods such as pour molding can be used.

[0114] The curing method after pouring the mixed material into the formwork until demolding is not particularly limited, and general curing methods such as air curing, humid air curing, underwater curing, and steam curing can be employed.

[0115] [Demolding process] This process involves demolding the hardened hydraulic composition, which is formed from the hardened mixture inside the mold, from the mold after the mixture has hardened.

[0116] [High strength curing process] This process is an optional step that can be set between the demolding process and the carbonation curing process, and is a process for increasing the strength of the hardened body of the hydraulic composition.

[0117] In this process, the hardened body of the hydraulic composition demolded from the mold has a compressive strength of preferably 3 N / mm². 2More preferably 5 N / mm 2 The above is particularly preferably 10 N / mm 2 By allowing the material to cure to this extent, the strength of the carbonated cured material after carbonation curing (for example, the compressive strength of mortar or concrete) can be increased.

[0118] The curing method is not particularly limited; for example, general curing methods such as air curing, humid air curing, underwater curing, and steam curing can be used. However, "curing" in the high-strength curing process does not include carbonation curing.

[0119] [Carbonation curing process] This process involves carbonizing the hardened hydraulic composition that has been demolded from the mold, in order to obtain a carbonated hardened body obtained by carbonizing the hardened hydraulic composition.

[0120] In this process, the concentration of carbon dioxide gas used for carbonation curing is preferably 1% by volume or more, more preferably 3% by volume or more, even more preferably 10% by volume or more, even more preferably 50% by volume or more, and particularly preferably 60% by volume or more. If the above concentration is 1% by volume or more, the amount of carbon dioxide absorbed in the carbonation curing process can be increased.

[0121] The upper limit of the carbon dioxide gas concentration is not particularly limited; a higher concentration of carbon dioxide gas can increase the amount of carbon dioxide absorbed. However, from the viewpoint of reducing the cost of curing equipment, etc., it is preferably 90% by volume or less, more preferably 70% by volume or less, and particularly preferably 50% by volume or less.

[0122] Furthermore, while the temperature in the carbonation curing process is not particularly limited, it is preferably 5°C to 100°C, more preferably 10°C to 50°C, and most preferably 15°C to 35°C. If the temperature in the carbonation curing process is within the above range, the strength of the carbonized cured product can be increased. In addition, the productivity of products made from the carbonized cured product is improved.

[0123] Furthermore, the carbonized hardened body using the wollastonite-containing calcined product provided by the present invention exhibits a significant reduction in carbon dioxide emissions even when carbonization curing is performed at relatively low temperatures (for example, 5°C to 30°C).

[0124] The relative humidity in this process is not particularly limited, but is preferably 20% to 90%, more preferably 30% to 80%, and most preferably 40% to 70%. If the relative humidity is 20% or higher, the productivity of the carbonated cured product will be further improved and the strength of the carbonated cured product will be greater. It is difficult to achieve a relative humidity exceeding 90%, and the costs associated with equipment, etc., will be excessive.

[0125] In the carbonation curing process, it is preferable to perform the carbonation curing so that the carbonation depth from the surface of the carbonized cured body is preferably 2 mm or more, more preferably 5 mm or more, even more preferably 8 mm or more, and particularly preferably 10 mm or more. By performing the carbonation curing so that the carbonation depth is 2 mm or more, a larger amount of carbon dioxide can be absorbed by the carbonized cured body. Specifically, the carbonation depth can be made 2 mm or more by appropriately adjusting the carbon dioxide gas concentration, temperature, relative humidity, and curing time in the carbonation curing process described above.

[0126] Furthermore, from the viewpoint of absorbing carbon dioxide in a short time, it is preferable to perform carbonation curing so that the carbonation depth is 2 mm or more, preferably at 1 day after demolding, and more preferably at 3 days after demolding.

[0127] Furthermore, the "carbonation depth from the surface of the carbonated hardened material" can be measured in accordance with "JIS A 1152:2018 (Method for measuring the carbonation depth of concrete)."

[0128] The resulting carbonated hardened material can be used as roadbed material, interlocking blocks, etc. Furthermore, even after being installed as roadbed material, it can continue to absorb and fix carbon dioxide.

[0129] Furthermore, if the hydraulic composition contains calcined aggregate (aggregate made from the calcined material described above), a carbonation treatment may be performed on the calcined aggregate before the compound preparation step, from the viewpoint of densifying it and increasing the aggregate strength. The carbonation treatment can be performed, for example, by wetting the aggregate and leaving it to stand in the presence of carbon dioxide gas. However, if the calcined aggregate is excessively carbonated at this time, the carbonation reaction will not occur during the carbonation curing process, and an improvement in the strength of the carbonized hardened body after carbonation curing may not be obtained.

[0130] The carbonized hardened body obtained by the above manufacturing method exhibits a reduction in carbon dioxide emissions during its production by preferably 15% or more, more preferably 20% or more, even more preferably 30% or more, and particularly preferably 40% or more, compared to cases where general Portland cement is used instead of the calcined aggregate (the calcined aggregate mentioned above), or where general aggregate is used instead of the calcined aggregate. Furthermore, the reduction in the strength (e.g., compressive strength) of the carbonized hardened body is preferably 50% or less, more preferably 40% or less. [Examples]

[0131] The present invention will be described in more detail below with reference to test examples. However, the scope of the present invention is not limited by these test examples.

[0132] [Test Example 1] We conducted heat treatments on masado soil, which is commonly found in construction waste and whose main mineral is alkali feldspar, at various temperature levels, and analyzed the mineral and chemical composition of the resulting heat-treated samples. In addition, we performed some control tests using silica sand, which is known to have a relatively low alkali content in its chemical composition.

[0133] [1. Test materials] • Decomposed granite: Obtained from a building materials supplier. • Silica sand: Kashima No. 6 silica sand, obtained from a sand manufacturer. • Calcium carbonate: Special grade reagent (manufactured by Kanto Chemical Co., Ltd., powder, purity 99.5% or higher) • Calcium chloride: Special grade reagent (manufactured by Kanto Chemical Co., Ltd., powder, purity 95.0% or higher)

[0134] [2. Analysis method] • Powder X-ray diffractometer: Bruker / D8 advanced (qualitative analysis, XRD / Rietveld analysis) • X-ray fluorescence analyzer: Rigaku / ZSX Primus II (analysis using the fundamental parameter method (FP method)) • Potassium (K) concentration analysis: SII Nanotechnology / SPECTRO BLUE EOP (wet analysis: acid hydrolysis-ICP emission spectroscopy)

[0135] [3. Characteristics of the test sample] Table 1 shows the results obtained by XRD qualitative analysis of the mineral composition of the masado soil or silica sand used in the test.

[0136] [Table 1]

[0137] Table 2 shows the results obtained from XRF (FP method) analysis of the chemical composition of the masado soil or silica sand used in the test, or the chemical composition of samples prepared by adding calcium carbonate (Ca source) to masado soil or silica sand.

[0138] [Table 2]

[0139] The water hardness modulus (HM) was calculated using the mass percentage of the chemical composition obtained from XRF analysis, according to the following formula. HM[-]=(CaO[%]) / {(SiO2[%])+(Al2O3[%])+(Fe2O3[%])}

[0140] [4. Examination Level] Table 3 shows the test levels.

[0141] [Table 3]

[0142] [5. Heat treatment] Test samples of levels 1 to 10 were subjected to heat treatment according to the following processing conditions. • Furnace used for heating: Box-type electric furnace (Motoyama Co., Ltd. S7-2035D-OP) • Heating temperature: As per test standards • Heating time: 60 minutes

[0143] [6.Results] Table 4 shows the XRD / Rietveld analysis results of the heat-treated samples, along with information on the composition of the pre-treatment samples and the potassium (K) removal rate obtained by wet analysis.

[0144] [Table 4]

[0145] Table 5 shows the results of XRF (FP method) analysis of the heat-treated samples, along with information on the composition of the pre-treatment samples and the potassium (K) removal rate obtained by wet analysis, similar to Table 4.

[0146] [Table 5]

[0147] Figure 3 shows graphs of the wollastonite production amount and potassium (K) removal rate for levels 1, 2, 7, and 9 (heating temperature was standardized at 1,200°C and Cl / K ratio was 2).

[0148] As shown in Figure 3, the amount of wollastonite produced increased with increasing water hardness (HM) of the raw material mixture, and the potassium (K) removal rate also increased.

[0149] Figure 4 shows the results of wollastonite production and potassium (K) removal rate for levels 5 to 8 (with a water hardness (HM) of 0.54 and a Cl / K ratio of 2).

[0150] As shown in Figure 4, the amount of wollastonite produced increased with increasing heat treatment temperature, and the potassium (K) removal rate also increased.

[0151] Figure 5 shows graphs of the wollastonite production amount and potassium (K) removal rate for levels 3, 4, and 7 (heating temperature standardized at 1,200°C and hydraulic hardness (HM) of 0.54).

[0152] As shown in Figure 5, the amount of wollastonite produced increased with increasing Cl / K ratio, and the potassium (K) removal rate also increased.

[0153] Figure 6 shows graphs of the wollastonite production amount and potassium (K) concentration before and after treatment for Level 7 and Level 10 (heating temperature standardized at 1,200°C and hydraulic hardness (HM) of 0.54).

[0154] As shown in Figure 6, under the heat treatment conditions in this test example, using decomposed granite as the silicate raw material resulted in a greater amount of wollastonite being produced than using silica sand as the silicate raw material.

[0155] From the above results, it became clear that by adjusting the hydraulic coefficient (HM) and Cl / K ratio using a raw material blend containing masado (decomposed granite) as a siliceous raw material, wollastonite-containing calcined products can be obtained more efficiently.

[0156] Furthermore, when any of the parameters—hydraulic hardness (HM), heating temperature, and Cl / K ratio—were changed across all levels, the amount of wollastonite produced and the potassium (K) removal rate showed a good correlation. This was thought to be due to a mechanism in which the removal of alkali (K,Na) from alkali feldspar (KAlSi3O8,NaAlSi3O8) contained in the decomposed granite soil caused the more reactive SiO2 to react with a Ca source, resulting in favorable wollastonite formation. It was also thought that increasing the hydraulic hardness (HM) favorably replenished the Ca source necessary for wollastonite formation, increasing the heating temperature favorably increased the reaction rate of wollastonite formation, and increasing the Cl / K ratio promoted the removal of alkali metals such as potassium (K), which are present in a poorly water-soluble state as constituent elements of silicate minerals such as alkali feldspar. In all cases, the amount of wollastonite produced was thought to be higher.

[0157] On the other hand, silica sand produced less wollastonite than masado soil under conditions where the hydraulic hardness (HM) and heating temperature were the same. This was thought to be because silica sand has a higher crystallinity of siliceous material, resulting in lower reactivity with the Ca source compared to masado soil.

[0158] [Test Example 2] Biomass ash generated from a biomass power plant was subjected to heat treatment at various levels, and the mineral and chemical compositions of the resulting heat-treated products were analyzed.

[0159] [1. Test materials] • Biomass ash: Fly ash generated from a biomass power plant (furnace type: circulating fluidized bed boiler (CFB), fuel: 100% coconut shells (PKS)) • Calcium carbonate: Special grade reagent (manufactured by Kanto Chemical Co., Ltd., powder, purity 99.5% or higher) • Calcium chloride: Special grade reagent (manufactured by Kanto Chemical Co., Ltd., powder, purity 95.0% or higher) Analysis method

[0160] [2. Analysis method] • Powder X-ray diffractometer: Bruker / D8 advanced (qualitative analysis, XRD / Rietveld analysis) • X-ray fluorescence analyzer: Rigaku / ZSX Primus II (analysis using the fundamental parameter method (FP method)) • Potassium (K) concentration analysis: SII Nanotechnology / SPECTRO BLUE EOP (wet analysis: acid hydrolysis-ICP emission spectroscopy)

[0161] [3. Characteristics of the test sample] Table 6 shows the results obtained by XRD qualitative analysis of the mineral composition of the biomass ash used in the experiment.

[0162] [Table 6]

[0163] Table 7 shows the results obtained from XRF (FP method) analysis of the chemical composition of the biomass ash used in the test, or the chemical composition of samples prepared by adding calcium carbonate (Ca source) to biomass ash.

[0164] [Table 7]

[0165] The hydraulic hardness modulus (HM) was calculated using the mass percentage of the chemical composition obtained from XRF analysis, in the same manner as in Test Example 1.

[0166] [4. Examination Level] Table 8 shows the test levels.

[0167] [Table 8]

[0168] [5. Heat treatment] Test samples of levels 1 to 9 were subjected to heat treatment according to the following processing conditions. • Furnace used for heating: Box-type electric furnace (Motoyama Co., Ltd. S7-2035D-OP) • Heating temperature: As per test standards • Heating time: 60 minutes

[0169] [6.Results] Table 9 shows the XRD / Rietveld analysis results of the heat-treated samples, along with information on the composition of the pre-treatment samples and the potassium (K) removal rate obtained by wet analysis.

[0170] [Table 9]

[0171] Table 10 shows the results of XRF (FP method) analysis of the heat-treated samples, along with information on the composition of the pre-treatment samples and the potassium (K) removal rate obtained by wet analysis, similar to Table 4.

[0172] [Table 10]

[0173] Figure 7 shows graphs of the wollastonite production amount and potassium (K) removal rate for levels 1, 5, and 8 (heating temperature 1,000°C, Cl / K ratio 2), as well as levels 2, 7, and 9 (heating temperature 1,200°C, Cl / K ratio 2).

[0174] As shown in Figure 7, the amount of wollastonite produced increased with increasing water hardness (HM) of the raw material mixture. Furthermore, under heating conditions of 1,200°C, the potassium (K) removal rate also increased.

[0175] Figure 8 shows a graph of the wollastonite production amount and potassium (K) removal rate for levels 5 to 7 (with a water hardness (HM) of 0.54 and a Cl / K ratio of 2).

[0176] As shown in Figure 8, the amount of wollastonite produced increased with increasing heat treatment temperature, and the potassium (K) removal rate also increased.

[0177] Figure 9 shows the results of wollastonite production and potassium (K) removal rate for levels 3 to 5 (heating temperature standardized at 1,000°C and water hardness (HM) standardized at 0.54) in graph form.

[0178] As shown in Figure 9, the amount of wollastonite produced increased with increasing Cl / K ratio, and the potassium (K) removal rate also increased.

[0179] From the above results, it became clear that, in a raw material formulation containing biomass ash as a silicate raw material, wollastonite-containing calcined products can be obtained more efficiently by adjusting the hydraulic coefficient (HM) and Cl / K ratio by adjusting the Ca source and / or Cl source added to it.

[0180] Furthermore, when any of the parameters—hydraulic hardness (HM), heating temperature, and Cl / K ratio—were changed across all levels, the amount of wollastonite produced and the potassium (K) removal rate showed a good correlation. This suggests that the removal of alkali (K,Na) from amorphous components such as potassium glass (K2O-4SiO2), which is abundant in biomass ash, and other alkali feldspars (KAlSi3O8,NaAlSi3O8), increased the reactivity of SiO2, which then reacted with a Ca source to produce wollastonite. It is also thought that increasing the hydraulic hardness (HM) effectively replenished the Ca source necessary for wollastonite formation, increasing the heating temperature effectively increased the reaction rate of wollastonite formation, and increasing the Cl / K ratio promoted the removal of alkali metals such as potassium (K), which are present in a poorly water-soluble state, either embedded in amorphous silica such as potassium glass or as constituent elements of silicate minerals such as alkali feldspar. In all cases, the amount of wollastonite produced was thus increased.

Claims

1. A raw material preparation process involves blending a Ca source and a Cl source with a siliceous raw material, and then calcining the raw material preparation obtained through the raw material preparation process to produce wollastonite (CaSiO ３ A method for producing a wollastonite-containing calcined product, comprising a mineral formation step that causes the formation of a wollastonite-containing product, The siliceous raw material is derived from at least one selected from the group consisting of biomass ash and construction-generated soil. The aforementioned raw material mixture has a hydraulic coefficient (H.M.) of 0.2 to 1.0, a Cl / K ratio of 0.5 to 4 for the amount of Cl molars in the siliceous raw material containing the Cl source, and a silicicity (S.M.) of 3.0 to 20.

0. CaO and SiO in the aforementioned raw material blend ２ The mass ratio (CaO / SiO ２ ) is 0.5 to 1.2, Al ２ O ３ The proportion (based on ignition raw materials) is 1.0% by mass to 7.0% by mass, and the proportion of alkali metals (based on ignition raw materials) is oxide (R ２ In terms of O) conversion, this is 0.3% by mass to 4.0% by mass. The manufacturing method, wherein the siliceous raw material is a raw material composition containing an alkali metal in a poorly water-soluble state.

2. A raw material preparation process involves blending a Ca source and a Cl source with a siliceous raw material, and then calcining the raw material preparation obtained through the raw material preparation process to produce wollastonite (CaSiO ３ A method for producing a wollastonite-containing calcined product, comprising a mineral formation step that causes the formation of a wollastonite-containing product, The siliceous raw material is derived from at least one selected from the group consisting of biomass ash and construction-generated soil. The aforementioned raw material mixture has a hydraulic coefficient (H.M.) of 0.2 to 1.0, a Cl / K ratio of 0.5 to 4 for the amount of Cl molars in the siliceous raw material containing the Cl source, and a silicicity (S.M.) of 3.0 to 20.

0. The mass ratio of CaO to SiO in the raw material blend ２ is 0.5 to 1.2, the proportion of Al ２ O (based on the calcined raw material) is 1.0% by mass to 7.0% by mass, and the proportion of alkali metals (based on the calcined raw material) is 0.3% by mass to 4.0% by mass in terms of oxide (R ２ O) conversion, ３ ２ ​​ The manufacturing method, wherein the siliceous raw material is a raw material composition containing alkali metals as constituent elements of silicate minerals and / or a raw material composition containing alkali metals embedded in amorphous silica.

3. A raw material preparation process involves blending a Ca source and a Cl source with a siliceous raw material, and then calcining the raw material preparation obtained through the raw material preparation process to produce wollastonite (CaSiO ３ A method for producing a wollastonite-containing calcined product, comprising a mineral formation step that causes the formation of a wollastonite-containing product, The siliceous raw material is derived from at least one selected from the group consisting of biomass ash and construction-generated soil. The aforementioned raw material mixture has a hydraulic coefficient (H.M.) of 0.2 to 1.0, a Cl / K ratio of 0.5 to 4 for the amount of Cl molars in the siliceous raw material containing the Cl source, and a silicicity (S.M.) of 3.0 to 20.

0. CaO and SiO in the aforementioned raw material blend ２ The mass ratio (CaO / SiO ２ ) is 0.5 to 1.2, Al ２ O ３ The proportion (based on ignition raw materials) is 1.0% by mass to 7.0% by mass, and the proportion of alkali metals (based on ignition raw materials) is oxide (R ２ In terms of O) conversion, this is 0.3% by mass to 4.0% by mass. The manufacturing method, wherein the Ca source is one or more selected from the group consisting of papermaking sludge, paper sludge incineration ash, sewage sludge incineration ash, ready-mix concrete sludge, chlorine bypass dust washing residue, by-product slaked lime, limestone, quicklime, and slaked lime.

4. A raw material preparation process involves blending a Ca source and a Cl source with a siliceous raw material, and then calcining the raw material preparation obtained through the raw material preparation process to produce wollastonite (CaSiO ３ A method for producing a wollastonite-containing calcined product, comprising a mineral formation step that causes the formation of a wollastonite-containing product, The siliceous raw material is derived from at least one selected from the group consisting of biomass ash and construction-generated soil. The aforementioned raw material mixture has a hydraulic coefficient (H.M.) of 0.2 to 1.0, a Cl / K ratio of 0.5 to 4 for the amount of Cl molars in the siliceous raw material containing the Cl source, and a silicicity (S.M.) of 3.0 to 20.

0. CaO and SiO in the aforementioned raw material blend ２ The mass ratio (CaO / SiO ２ ) is 0.5 to 1.2, Al ２ O ３ The proportion (based on ignition raw materials) is 1.0% by mass to 7.0% by mass, and the proportion of alkali metals (based on ignition raw materials) is oxide (R ２ In terms of O) conversion, this is 0.3% by mass to 4.0% by mass. The manufacturing method, wherein the Cl source is one or more selected from the group consisting of chlorine-containing combustible waste and inorganic chlorine compounds.

5. A raw material preparation process involves blending a Ca source and a Cl source with a siliceous raw material, and then calcining the raw material preparation obtained through the raw material preparation process to produce wollastonite (CaSiO ３ A method for producing a wollastonite-containing calcined product, comprising a mineral formation step that causes the formation of a wollastonite-containing product, The siliceous raw material is derived from at least one selected from the group consisting of biomass ash and construction-generated soil. The aforementioned raw material mixture has a hydraulic coefficient (H.M.) of 0.2 to 1.0, a Cl / K ratio of 0.5 to 4 for the amount of Cl molars in the siliceous raw material containing the Cl source, and a silicicity (S.M.) of 3.0 to 20.

0. CaO and SiO in the aforementioned raw material blend ２ The mass ratio (CaO / SiO ２ ) is 0.5 to 1.2, Al ２ O ３ The proportion (based on ignition raw materials) is 1.0% by mass to 7.0% by mass, and the proportion of alkali metals (based on ignition raw materials) is oxide (R ２ In terms of O) conversion, this is 0.3% by mass to 4.0% by mass. The manufacturing method comprising further washing and / or classifying the calcined product obtained through the mineral formation process to obtain the wollastonite-containing calcined product.

6. A raw material preparation process involves blending a Ca source and a Cl source with a siliceous raw material, and then calcining the raw material preparation obtained through the raw material preparation process to produce wollastonite (CaSiO ３ A method for producing a wollastonite-containing calcined product, comprising a mineral formation step that causes the formation of a wollastonite-containing product, The siliceous raw material is derived from at least one selected from the group consisting of biomass ash and construction-generated soil. The aforementioned raw material mixture has a hydraulic coefficient (H.M.) of 0.2 to 1.0, a Cl / K ratio of 0.5 to 4 for the amount of Cl molars in the siliceous raw material containing the Cl source, and a silicicity (S.M.) of 3.0 to 20.

0. CaO and SiO in the aforementioned raw material blend ２ The mass ratio (CaO / SiO ２ ) is 0.5 to 1.2, Al ２ O ３ The proportion (based on ignition raw materials) is 1.0% by mass to 7.0% by mass, and the proportion of alkali metals (based on ignition raw materials) is oxide (R ２ In terms of O) conversion, this is 0.3% by mass to 4.0% by mass. The manufacturing method comprising crushing and / or classifying the siliceous raw material in advance before using it in the raw material blending process, and then using it in the raw material blending process.

7. A raw material preparation process involves blending a Ca source and a Cl source with a siliceous raw material, and then calcining the raw material preparation obtained through the raw material preparation process to produce wollastonite (CaSiO ３ A method for producing a wollastonite-containing calcined product, comprising a mineral formation step that causes the formation of a wollastonite-containing product, The siliceous raw material is derived from at least one selected from the group consisting of biomass ash and construction-generated soil. The aforementioned raw material mixture has a hydraulic coefficient (H.M.) of 0.2 to 1.0, a Cl / K ratio of 0.5 to 4 for the amount of Cl molars in the siliceous raw material containing the Cl source, and a silicicity (S.M.) of 3.0 to 20.

0. CaO and SiO in the aforementioned raw material blend ２ The mass ratio (CaO / SiO ２ ) is 0.5 to 1.2, Al ２ O ３ The proportion (based on ignition raw materials) is 1.0% by mass to 7.0% by mass, and the proportion of alkali metals (based on ignition raw materials) is oxide (R ２ In terms of O) conversion, this is 0.3% by mass to 4.0% by mass. The manufacturing method comprising crushing and / or classifying the raw material mixture in advance before subjecting it to the mineral formation process, and then subjecting it to the mineral formation process.

8. A raw material preparation process involves blending a Ca source and a Cl source with a siliceous raw material, and then calcining the raw material preparation obtained through the raw material preparation process to produce wollastonite (CaSiO ３ A method for producing a wollastonite-containing calcined product, comprising a mineral formation step that causes the formation of a wollastonite-containing product, The siliceous raw material is derived from at least one selected from the group consisting of biomass ash and construction-generated soil. The aforementioned raw material mixture has a hydraulic coefficient (H.M.) of 0.2 to 1.0, a Cl / K ratio of 0.5 to 4 for the amount of Cl molars in the siliceous raw material containing the Cl source, and a silicicity (S.M.) of 3.0 to 20.

0. CaO and SiO in the aforementioned raw material blend ２ The mass ratio (CaO / SiO ２ ) is 0.5 to 1.2, Al ２ O ３ The proportion (based on ignition raw materials) is 1.0% by mass to 7.0% by mass, and the proportion of alkali metals (based on ignition raw materials) is oxide (R ２ In terms of O) conversion, this is 0.3% by mass to 4.0% by mass. The manufacturing method comprising recovering chlorine from the exhaust gas discharged by calcination in the mineral formation process and reusing it as the Cl source.

9. A method for producing a wollastonite-containing calcined product according to claim 1, comprising calcining the raw material mixture at 900°C to 1,300°C.

10. A method for producing a wollastonite-containing calcined product according to claim 2, wherein the raw material mixture is calcined at 900°C to 1,300°C.

11. A method for producing a wollastonite-containing calcined product according to claim 3, comprising calcining the aforementioned raw material mixture at 900°C to 1,300°C.

12. A method for producing a wollastonite-containing calcined product according to claim 4, comprising calcining the aforementioned raw material mixture at 900°C to 1,300°C.

13. A method for producing a wollastonite-containing calcined product according to claim 5, comprising calcining the aforementioned raw material mixture at 900°C to 1,300°C.

14. A method for producing a wollastonite-containing calcined product according to claim 6, comprising calcining the raw material mixture at 900°C to 1,300°C.

15. A method for producing a wollastonite-containing calcined product according to claim 7, wherein the raw material mixture is calcined at 900°C to 1,300°C.

16. A method for producing a wollastonite-containing calcined product according to claim 8, comprising calcining the aforementioned raw material mixture at 900°C to 1,300°C.

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