Method for producing clinker powder

Abstract

This invention provides a method for producing clinker powder that can be manufactured at a lower firing temperature using cement hydrate-containing materials (e.g., concrete sludge, waste concrete) as raw materials, and can further harden by absorbing carbon dioxide during the curing process to generate carbonates. [Solution] A method for producing clinker powder comprising the steps of: obtaining cement hydrate-containing powder from one or more cement hydrate-containing materials by one or more operations including at least one powdering operation consisting of crushing or grinding; preparing a firing material containing cement hydrate-containing powder; firing the firing material at 950 to 1,100°C; and crushing clinker to obtain clinker powder, wherein the clinker powder has a mineral composition in which the water hardness is 0.2 to 1.5, the silica content is 1.5 to 3.3, the iron content is 1.7 to 3.5, and the total content of aluminum oxide and iron oxide is 7 to 18% by mass.

Description

Technical Field

[0001] The present invention relates to a method for producing clinker powder.

Background Art

[0002] From the viewpoint of volume reduction of waste, etc., techniques for recycling waste concrete are known. For example, Patent Document 1 describes a method for recycling waste concrete, which is characterized in that fine powder obtained by crushing and then sieving waste concrete materials is sintered to form aggregates. Also, Patent Document 2 describes a cement admixture obtained by firing a waste material hardened body containing cement hydrate at 800 to 1200°C and containing gehlenite (CaO - Al2O3 - SiO2 compound). On the other hand, for suppressing global warming, reduction of carbon dioxide emissions has become an important issue. As a concrete mixture capable of absorbing a large amount of carbon dioxide during the curing process, for example, Patent Document 3 describes a concrete mixture containing, as powder components, one or two of γ-C2S (symbol γ), steelmaking slag powder (symbol B), and Portland cement (symbol C), where the total of γ and B in the total content of γ, B, and C is 25 to 95% by mass, and the water-cement ratio W / C is 80 to 250%.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] The object of the present invention is to provide a clinker powder that can be produced at a lower firing temperature using cement hydrate-containing materials (e.g., concrete sludge, waste concrete) as raw materials, and that can harden by absorbing carbon dioxide during the curing process to generate carbonates, as well as a method for producing the same. [Means for solving the problem]

[0005] The inventors of the present invention have diligently studied to solve the above problems and have found that the above objectives can be achieved by using clinker powder made from a calcined product of a calcination material containing cement hydrate powder, having a mineral composition in which the hydraulic modulus (HM) is 1.8 or less, the silicic acid modulus (SM) is 1.5 to 3.3, the iron modulus (IM) is 1.7 to 3.5, and the total content of aluminum oxide (Al2O3) and iron oxide (Fe2O3) is 7 to 18% by mass. In other words, the present invention provides the following [1] to [9]. [1] A clinker powder comprising a calcined product of a calcination material containing cement hydrate powder, characterized in that it has a mineral composition having a hydraulic modulus (HM) of 1.8 or less, a silicate modulus (SM) of 1.5 to 3.3, an iron modulus (IM) of 1.7 to 3.5, and a total content of aluminum oxide (Al2O3) and iron oxide (Fe2O3) of 7 to 18% by mass. [2] The clinker powder according to [1], wherein the total alkali content is 4.0% by mass or less. [3] The clinker powder according to [1] or [2], wherein the free lime (f-CaO) content is 8% by mass or less.

[0006] [4] A method for producing clinker powder according to any of [1] to [3] above, comprising: a powder preparation step of obtaining cement hydrate-containing powder from one or more cement hydrate-containing materials by one or more operations including at least one powdering operation consisting of crushing or grinding, and then preparing a firing material containing the cement hydrate-containing powder; a firing step of firing the firing material at 950 to 1,400°C to obtain clinker; and a grinding step of grinding the clinker to obtain clinker powder. [5] A method for producing clinker powder according to any of [1] to [3] above, comprising: a powder preparation step of obtaining cement hydrate-containing powder from each of two or more cement hydrate-containing materials by one or more operations including at least a pulverization operation consisting of crushing or grinding, and then preparing firing materials containing the cement hydrate-containing powder to obtain two or more firing materials; a firing step of firing each of the two or more firing materials at 950 to 1,400°C (however, the above temperatures for the two or more firing materials may be the same or different from each other) to obtain two or more clinkers; and a crushing and mixing step of crushing the two or more clinkers and then mixing them to obtain clinker powder, or mixing the two or more clinkers and then crushing them to obtain clinker powder. [6] A method for producing clinker powder according to [4] or [5], wherein the cement hydrate-containing material is concrete or mortar, and in the powder preparation step, the cement hydrate-containing material is subjected to at least one of crushing and coarse crushing, and then a portion of the aggregate is recovered to obtain a coarse crushed material from which a portion of the aggregate has been removed, and then the coarse crushed material is subjected to the pulverization operation.

[0007] [7] A cement for carbonation curing characterized by containing clinker powder and gypsum as described in any of [1] to [3] above. [8] The carbonation-curing cement according to [7], comprising Portland cement clinker powder, wherein the amount of clinker powder in 100 parts by mass of the total amount of clinker powder and Portland cement clinker powder is 50 parts by mass or more. [9] A method for producing a cement-containing hardened body containing cement for carbonation curing, comprising carbonation curing a cement composition containing the cement for carbonation curing described in [7] or [8] and water. [Effects of the Invention]

[0008] According to the present invention, cement hydrate-containing materials (for example, concrete sludge, waste concrete) can be used as raw materials, thereby promoting the utilization of waste. Furthermore, because clinker can be produced at lower firing temperatures, the energy costs required for firing can be reduced, and the amount of carbon dioxide generated during firing can be reduced. Furthermore, the cement composition containing the clinker powder of the present invention hardens by absorbing carbon dioxide and generating carbonates during the curing process, thus reducing carbon dioxide emissions. [Modes for carrying out the invention]

[0009] The clinker powder of the present invention is a clinker powder made from a calcined product of a calcination material containing cement hydrate powder, and has a mineral composition in which the hydraulic modulus (HM) is 1.8 or less, the silicic acid modulus (SM) is 1.5 to 3.3, the iron modulus (IM) is 1.7 to 3.5, and the total content of aluminum oxide (Al2O3) and iron oxide (Fe2O3) is 7 to 18% by mass.

[0010] Cement hydrate-containing powder refers to a powdered substance containing cement hydrate. Examples of materials containing cement hydrate include cement paste, mortar, concrete, concrete sludge (sludge generated when cleaning agitator trucks or concrete manufacturing equipment), returned concrete, and leftover concrete (concrete that was not used up on site). In particular, from the viewpoint of promoting the effective utilization of waste, cementitious hardened materials such as waste cement paste, waste mortar, and waste concrete generated during the demolition of buildings (cement hydrate-containing materials in which the hydration reaction of cement has proceeded sufficiently and most of the cement clinker minerals have been converted into cement hydrates) are preferred. These may be used individually or in combination of two or more types.

[0011] If the cement hydrate-containing material is in a fluid state (i.e., the hydration reaction of the cement has not progressed sufficiently and is in the setting stage), the water contained in the cement hydrate-containing material may be removed by solid-liquid separation, or the cement hydrate-containing material may be dried. A calcination material containing cement hydrate powder can be obtained by crushing or grinding the cement hydrate-containing material in the powder preparation process described later. Furthermore, crushing or coarse grinding may be performed before crushing or grinding. Furthermore, when using concrete sludge or returned concrete, the aggregate contained in the cement hydrate-containing powder may be separated and removed beforehand.

[0012] In order to bring the hydraulic content, silica content, iron content, and total content of aluminum oxide and iron oxide in the resulting clinker powder to a desired range, the firing material may contain other materials different from the cement hydrate-containing powder. Other materials include calcium-containing raw materials (CaO sources) such as limestone, quicklime, and slaked lime; silicon-containing raw materials (SiO2 sources) such as silica and clay; aluminum-containing raw materials (Al2O3 sources) such as clay; and iron-containing raw materials (Fe2O3 sources) such as iron slag and iron cake, which are common raw materials used in the manufacture of cement clinker. These raw materials may be used individually or in combination of two or more.

[0013] As another material, one or more selected from industrial waste, general waste, and construction-generated soil may be used (however, excluding the cement hydrate-containing powder described above). Here, industrial waste refers to waste generated along with business activities (however, excluding "construction-generated soil" described later). Examples of industrial waste include various sludges (e.g., sewage sludge, purified water sludge, iron-making sludge, etc.), construction waste materials, various incineration ashes (e.g., coal ash, chicken manure ash, livestock manure ash, biomass ash, sludge incineration ash), foundry sand, rock wool, waste glass, blast furnace secondary ash, various by-products, unused resources (materials remaining without being used, etc.), and the like. General waste refers to waste other than industrial waste (however, excluding "construction-generated soil" described later). Examples of general waste include dried sewage sludge powder, municipal waste incineration ash, shells, and the like. Examples of construction-generated soil include soil and earth and sand that are secondarily generated at construction sites and work sites, etc. (e.g., boring waste soil generated by excavation of the ground), surplus soil, waste soil, sludge (construction sludge; e.g., a mixture of cement milk and excavated soil generated in ground improvement work), and the like. These may be used alone or in combination of two or more.

[0014] The proportion of the cement hydrate-containing powder in the firing material is preferably 30% by mass or more, more preferably 40 - 90% by mass, and particularly preferably 50 - 80% by mass. If the above proportion is 30% by mass or more, the effective utilization of waste can be further promoted, clinker can be produced at a lower firing temperature, and the carbonation curing cement containing clinker powder can be made to absorb more carbon dioxide during the curing process.

[0015] The hydraulicity (H.M.) of the clinker powder is 1.8 or less, preferably 0.2 - 1.7, more preferably 0.3 - 1.5, still more preferably 0.4 - 1.2, and particularly preferably 0.5 - 1.0. When the hydraulicity exceeds 1.8, the easy burnability of the clinker decreases, and free lime (f·CaO) tends to remain, and it is necessary to raise the firing temperature when manufacturing the clinker. The silicate ratio (S.M.) of the clinker powder is 1.5 - 3.3, preferably 1.6 - 3.1, more preferably 1.7 - 3.0, still more preferably 1.8 - 2.95, still more preferably 2.4 - 2.9, still more preferably 2.5 - 2.9, still more preferably 2.6 - 2.9, and particularly preferably 2.75 - 2.9. When the silicate ratio is less than 1.5, the fluidity of the carbonation curing cement containing the clinker powder decreases. When the silicate ratio exceeds 3.3, the easy burnability of the clinker decreases, and unreacted silica (SiO2) tends to remain, and it is necessary to raise the firing temperature when manufacturing the clinker. The iron ratio (I.M) of the clinker powder is 1.7 - 3.5, preferably 1.8 - 3.4, more preferably 1.9 - 3.35, still more preferably 2.0 - 3.3, still more preferably 2.1 - 2.5, still more preferably 2.1 - 2.4, still more preferably 2.1 - 2.35, and particularly preferably 2.1 - 2.3. When the iron ratio is less than 1.7, the strength development of the carbonation curing cement containing the clinker powder decreases. When the iron ratio exceeds 3.5, the fluidity of the carbonation curing cement containing the clinker powder decreases.

[0016] Note that the hydraulicity, silicate ratio, and iron ratio can be calculated using the following formulas, respectively. Hydraulicity = CaO / (SiO2 + Al2O3 + Fe2O3) Silicate ratio = SiO2 / (Al2O3 + Fe2O3) Iron ratio = Al2O3 / Fe2O3 (The chemical formulas in the above formulas represent the content rates (mass%) of the compounds represented by the above chemical formulas in the clinker powder.)

[0017] The total content of aluminum oxide (Al2O3) and iron oxide (Fe2O3) in 100% by mass of clinker powder is 7 to 18% by mass, preferably 8 to 17% by mass, more preferably 9 to 17.5% by mass, and particularly preferably 11 to 17% by mass. If the above content is less than 7% by mass, the ease of firing of the clinker decreases, free lime (f·CaO) tends to remain, and it becomes necessary to raise the firing temperature when producing the clinker. If the above content exceeds 18% by mass, the amount of carbon dioxide absorbed during the curing process of the carbonation-cured cement containing the above clinker powder decreases.

[0018] The total alkali content in the clinker powder is preferably 4.0% by mass or less, more preferably 0.7 to 3.0% by mass, even more preferably 1.0 to 2.8% by mass, and particularly preferably 1.4 to 2.5% by mass. If the above amount is 4.0% by mass or less, alkali-aggregate reaction can be further suppressed. The total alkalinity is calculated using the following formula (1). Total alkali content (R2O) = Na2O + 0.658K2O ... (1) (In formula (1), Na2O represents the content (mass%) of sodium oxide in the clinker powder, and K2O represents the content (mass%) of potassium oxide in the clinker powder.)

[0019] The free lime (f-CaO) content in the clinker powder is preferably 8% by mass or less, more preferably 7.5% by mass or less, even more preferably 5% by mass or less, even more preferably 2% by mass or less, and particularly preferably 1% by mass or less. If the above content is 8% by mass or less, the strength development of the carbonation-cured cement containing clinker powder will improve.

[0020] The clinker powder preferably contains wollastonite (CaO·SiO2), lanquinite (3CaO·2SiO2), or β-belite (β-2CaO·SiO2). Wollastonite (CaO·SiO2), lanquinite (3CaO·2SiO2), and β-belite (β-2CaO·SiO2) are all carbonate-curing minerals. When clinker powder contains the above minerals, it can absorb more carbon dioxide during the curing process of the carbonation-curing cement containing the clinker powder, and the strength of the hardened body containing the carbonation-curing cement can be further increased. Furthermore, because the amount of alite (3CaO·SiO2) with a high Ca / Si ratio is kept low, carbon dioxide can be efficiently absorbed during the curing process of carbonation-cured cement containing the above-mentioned clinker powder.

[0021] 1: First manufacturing method One example of a method for producing clinker powder using cement hydrate-containing powder is a production method that includes a powder preparation step of preparing a calcination material containing cement hydrate-containing powder by obtaining cement hydrate-containing powder from one or more cement hydrate-containing materials through one or more operations including at least one powdering operation consisting of crushing or grinding, a calcination step of calcining the calcination material at 950 to 1,400°C to obtain clinker, and a grinding step of grinding the clinker to obtain clinker powder. The following explains each step in detail.

[0022] [Powder preparation process] This process involves obtaining cement hydrate-containing powder from one or more cement hydrate-containing materials through one or more operations, including at least one operation of pulverization consisting of crushing or grinding, and then preparing a firing material containing the cement hydrate-containing powder. Cement hydrate-containing powder can be obtained by performing one or more operations on a cement hydrate-containing material, including at least one pulverization operation consisting of crushing or grinding. The pulverization operation, consisting of crushing or grinding, is not particularly limited as long as it can pulverize the cement hydrate-containing material. Examples include crushing using a ball mill or disc mill, or grinding using a commercially available grinding machine with a diamond grinding wheel. The cement hydrate-containing material may be one type or two or more types. When using two or more types of cement hydrate-containing materials, the above operation should be performed simultaneously on the two or more types of cement hydrate-containing materials.

[0023] The cement hydrate-containing powder may be used as is in the firing process as a firing material containing cement hydrate-containing powder. However, in order to bring the water hardness, silica content, iron content, and the total content of aluminum oxide and iron oxide in the clinker powder obtained in the grinding process described later into a desired range, other materials different from the cement hydrate-containing powder mentioned above may be included. A firing material containing cement hydrate powder can be prepared by appropriately mixing the cement hydrate-containing powder with other materials so that the hydraulic content, silica content, iron content, and total content of aluminum oxide and iron oxide in the resulting clinker powder are within a desired range.

[0024] In this process, if the cement hydrate-containing material is mortar or concrete containing aggregate (fine aggregate, coarse aggregate), from the viewpoint of facilitating the powdering operation, at least one of crushing and coarse crushing may be performed on the cement hydrate-containing material, and then a portion of the aggregate may be recovered using a sieve or the like to remove a portion of the aggregate to obtain a coarsely crushed material, after which the powdering operation described above may be performed on the coarsely crushed material. Furthermore, when using two or more cement hydrate-containing materials, the two or more cement hydrate-containing materials may be crushed simultaneously, and then a portion of the aggregate may be recovered using a sieve or the like. Alternatively, each of the two or more cement hydrate-containing materials may be crushed separately, and then a portion of the aggregate may be recovered using a sieve or the like. Furthermore, if the cement hydrate-containing material is a slurry such as concrete sludge, drying may be performed before crushing or sieving.

[0025] [Firing process] This process involves firing a firing material containing cement hydrate powder at 950 to 1,400°C to obtain clinker. From the viewpoint of reducing the amount of free lime in the clinker powder and further improving the strength development of the carbonation-cured cement containing the clinker powder, the firing temperature in the firing process is 950°C or higher, preferably 975°C or higher, and more preferably 1,000°C or higher. Furthermore, from the viewpoint of reducing the energy cost required for firing and further reducing the amount of carbon dioxide generated during firing, the firing temperature is 1,400°C or lower, preferably 1,300°C or lower, more preferably 1,250°C or lower, even more preferably 1,100°C or lower, and particularly preferably 1,050°C or lower. [Grinding process] This process involves grinding clinker to obtain clinker powder. The method of grinding the clinker is not particularly limited and can be carried out using a general method, such as using a ball mill.

[0026] 2: Second manufacturing method Furthermore, as a method for producing the clinker powder of the present invention, clinker powder may be produced by mixing two or more types of clinker powder. Specifically, the manufacturing method includes a powder preparation step of obtaining cement hydrate-containing powder from each of two or more cement hydrate-containing materials by one or more operations including at least one powdering operation consisting of crushing or grinding, and then preparing firing materials containing the cement hydrate-containing powder to obtain two or more of the above firing materials; a firing step of firing each of the two or more of the above firing materials at 950 to 1,400°C to obtain two or more types of clinker; and a crushing and mixing step of crushing and mixing the two or more types of clinker and then mixing them to obtain clinker powder, or mixing the two or more types of clinker and then crushing them to obtain clinker powder. The following explains each step in detail.

[0027] [Powder preparation process] This process involves obtaining cement hydrate-containing powder from each of two or more cement hydrate-containing materials by one or more operations including at least one powdering operation consisting of crushing or grinding, and then preparing a firing material containing the above cement hydrate-containing powder to obtain two or more firing materials. The "pulverization operation consisting of crushing or grinding" is the same as the pulverization operation consisting of crushing or grinding in the powder preparation step of the first manufacturing method described above. The cement hydrate-containing powder may be used as is in the firing process as a firing material containing cement hydrate-containing powder. However, in order to bring the water hardness, silica content, iron content, and the total content of aluminum oxide and iron oxide in the clinker powder obtained in the grinding process described later to a desired range, the firing material may contain other materials different from the cement hydrate-containing powder described above. When the firing material contains other materials, the proportion of cement hydrate-containing powder in the firing material is preferably 30% by mass or more, more preferably 40-90% by mass, and particularly preferably 50-80% by mass.

[0028] In this process, if the cement hydrate-containing material is mortar or concrete containing aggregate (fine aggregate, coarse aggregate), the cement hydrate-containing material may be coarsely crushed to facilitate the pulverization process, and then a portion of the aggregate may be recovered using a sieve or the like to obtain a coarsely crushed material from which a portion of the aggregate has been removed. After that, the pulverization process described above may be performed on the coarsely crushed material.

[0029] [Firing process] This process involves firing each of the two or more firing materials prepared in the previous process at 950 to 1,400°C to obtain two or more types of clinker. The firing temperature is the same as the firing temperature in the firing step of the first manufacturing method. However, the above temperatures for each of the two or more firing materials may be the same or different from each other. [Grinding and mixing process] This process involves grinding two or more types of clinker and then mixing them to obtain clinker powder, or mixing two or more types of clinker and then grinding them to obtain clinker powder. The method for grinding the clinker is the same as the grinding method in the grinding step of the first manufacturing method described above.

[0030] The carbonicated cured cement of the present invention contains the above-mentioned clinker powder and gypsum. Examples of gypsum include anhydrous gypsum, dihydrate gypsum, hemihydrate gypsum, or mixtures thereof. The proportion of gypsum in the carbonated cured cement is preferably 0.1 to 5.0% by mass, more preferably 0.5 to 4.0% by mass, and particularly preferably 1.0 to 3.0% by mass, in terms of SO3. If the above proportion is 0.1% by mass or more, the usable time before hardening of the carbonated cured cement (the time during which good fluidity can be maintained) increases. If the amount is 5.0% by mass or less, the strength development of the carbonated cured cement improves.

[0031] The water used in this invention is not particularly limited, and examples include tap water and sludge water. The amount of water used is not particularly limited and can be any amount that is typical for pastes, mortars, or concrete. For example, the amount of water used is such that the mass ratio of water to carbonated curing cement (water / carbonated curing cement) is preferably 0.20 to 0.60, more preferably 0.23 to 0.50, and particularly preferably 0.23 to 0.40. If the above ratio is 0.20 or higher, workability is further improved. If the above ratio is 0.60 or lower, the strength development of the carbonated curing cement is further improved.

[0032] Carbonated cured cement may contain Portland cement clinker powder, for reasons such as ease of availability and improved strength development. The Portland cement clinker powder is not particularly limited, and various types of Portland cement clinker powders can be used, such as ordinary Portland cement clinker, rapid-strength Portland cement clinker, moderate-heat Portland cement clinker, and low-heat Portland cement clinker. The amount of the clinker powder of the present invention in a total of 100 parts by mass of the clinker powder of the present invention and Portland cement clinker powder is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, and particularly preferably 70 parts by mass or more. If the above amount is 50 parts by mass or more, more carbon dioxide can be absorbed during the curing process.

[0033] The carbonated cured cement of the present invention may contain other materials as needed. Other materials that may be added as needed include fine aggregate, coarse aggregate, various admixtures such as AE agents, water-reducing agents, high-performance water-reducing agents, and high-performance water-reducing agents, as well as various admixtures such as fly ash, silica fume, blast furnace slag fine powder, and siliceous mixtures (excluding silica fume).

[0034] The method for producing a hardened body containing carbon dioxide-cured cement using the carbon dioxide-cured cement of the present invention is not particularly limited, and any general method for producing paste, mortar, or concrete may be used. However, from the viewpoint of absorbing more carbon dioxide, a method of producing a hardened body containing carbon dioxide-cured cement by carbon dioxide-curing a cement composition containing carbon dioxide-cured cement and water is preferred. The above cement composition is, for example, poured into formwork or the like after the individual materials constituting the cement composition are mixed using a conventional mixer before the carbonation curing process. The concentration of carbon dioxide gas in the carbonation curing process is preferably 1% by volume or more, 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 concentration is 1% by volume or more, the amount of carbon dioxide absorbed in the carbonation curing process can be increased. 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 costs associated with curing equipment, etc., it is preferably 90% by volume, more preferably 85% by volume, and particularly preferably 80% by volume.

[0035] Furthermore, the temperature in the carbonation curing process is not particularly limited, but is preferably 5 to 100°C, more preferably 10 to 70°C, even more preferably 15 to 50°C, and most preferably 20 to 35°C. If the above temperature is 5°C or higher, the productivity of the cement-containing hardened material for carbonation curing is further improved, and the strength of the cement-containing hardened material for carbonation curing is further increased. If the above temperature exceeds 100°C, the energy cost of carbonation curing becomes excessive. Furthermore, while the relative humidity in the carbonation curing process is not particularly limited, it is preferably 20-90%, more preferably 30-80%, and most preferably 40-70%. If the relative humidity is 20% or higher, the productivity of the cement-containing hardened material for carbonation curing is further improved, and the strength of the cement-containing hardened material for carbonation curing is increased. It is difficult to raise the relative humidity above 90%, and the costs associated with equipment, etc., become excessive. [Examples]

[0036] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. [Production of powders A-D derived from cement hydrate-containing materials] A cement paste was prepared by mixing ordinary Portland cement having the chemical composition shown in Table 1 with water in a ratio of water to ordinary Portland cement (water / ordinary Portland cement) of 0.3 in a mixer (manufactured by Hobart). The mixture was then placed in a plastic container and cured for 7 days at 60°C and 80% relative humidity to produce a hardened cement paste. The hardened paste was then coarsely crushed until it was small enough to pass through a sieve with a mesh size of 5.0 mm. Next, the coarsely ground hardened material (indicated as "coarsely ground paste hardened material" in Table 2) and various special grade reagents (manufactured by Kanto Chemical Co., Ltd.: SiO2, Al2O3, Fe2O3, CaCO3, MgO, CaSO4·2H2O, Na2CO3, K2CO3) were mixed in the proportions shown in Table 2. The powder that passed through a sieve with a mesh size of 1.0 mm was further finely ground using a vibrating disc mill until it reached a particle size suitable for granulation, thereby obtaining powders A to D derived from cement hydrate-containing material (indicated as "powder" in Table 2).

[0037] [Table 1]

[0038] [Table 2]

[0039] [Production of powder E derived from cement hydrate-containing material] Ordinary Portland cement and water were added to a tank in a ratio of 0.5 (water / ordinary Portland cement) and mixed using a hand mixer to prepare a cement slurry. After mixing the cement slurry for 5 hours, it was filtered, and then dried at 60°C for 4 days to obtain a hardened paste (containing cement hydrate). The obtained hardened paste was coarsely crushed to a size that could pass through a 5.0 mm sieve to obtain a powder derived from the cement hydrate containing cement having the chemical composition shown in Table 3. The obtained powder was passed through a sieve with a mesh size of 1.0 mm, and then finely ground using a vibrating disc mill until it reached a particle size suitable for granulation, thereby obtaining a cement hydrate-derived powder (indicated as "powder" in Table 3) E.

[0040] [Table 3]

[0041] [Production of Powder F] Various special grade reagents (manufactured by Kanto Chemical Co., Ltd.: SiO2, Al2O3, Fe2O3, CaCO3, MgO, CaSO4·2H2O, Na2CO3, K2CO3) were mixed so that the chemical composition of the clinker powder matched the proportions shown in Table 4. The mixture was then finely ground using a vibrating disc mill to obtain powder F (which does not contain powder derived from cement hydrate-containing materials).

[0042] [Table 4]

[0043] [Example 1] A mixture consisting solely of powder A derived from cement hydrate was designated as firing material mixture 1. The firing material mixture 1 was compacted into cylindrical pellets with a diameter of 20 mm. Next, the pelletized firing material mixture 1 was placed on a platinum container and heated in a box-type electric furnace at a heating rate of 20°C / min until it reached 1,000°C, and then maintained at 1,000°C for 30 minutes for firing. Then, the platinum container was removed from the box-type electric furnace and rapidly cooled to room temperature. The calcined material (clinker) was coarsely ground in a stainless steel mortar to a size that could pass through a sieve with a mesh size of 5.0 mm, and then finely ground using a vibrating disc mill to obtain clinker powder. The chemical composition of the clinker powder, the total content of Al2O3 and Fe2O3 (indicated as "Al+Fe" in Table 5), the hydraulic ratio, the silica ratio, the iron ratio, and the total alkali content are shown in Table 5.

[0044] [Measuring the free lime content] The free lime content (in mass %) in the clinker powder was measured in accordance with the "Standard Test Method of the Cement Association of Japan (JCAS I-01-1997) (Method A for the Quantitative Determination of Free Calcium Oxide)". [Powder X-ray analysis] Qualitative analysis was performed on the clinker powder using a powder X-ray diffractometer.

[0045] [Example 2] In a box-type electric furnace, the temperature was raised at a rate of 20°C / min until it reached 1,000°C, which was then maintained for 30 minutes. After that, the temperature was raised at a rate of 20°C / min until it reached 1,200°C, which was then maintained for 30 minutes for firing. Subsequently, the platinum container was removed from the box-type electric furnace and rapidly cooled to room temperature in a room temperature environment. Except for these steps, the procedure was the same as in Example 1 to obtain clinker powder, after which free lime measurement and powder X-ray diffraction were performed.

[0046] [Example 3] A mixture consisting solely of powder B derived from cement hydrate was designated as the firing material mixture 2. Clinker powder was obtained in the same manner as in Example 1, except that calcination material mixture 2 was used instead of calcination material mixture 1. After that, free lime measurement and powder X-ray diffraction were performed. [Example 4] Clinker powder was obtained in the same manner as in Example 2, except that calcination material mixture 2 was used instead of calcination material mixture 1. After that, free lime measurement and powder X-ray diffraction were performed.

[0047] [Example 5] A mixture of firing materials 3 was prepared by mixing powder A derived from a cement hydrate-containing substance and powder C derived from a cement hydrate-containing substance in amounts such that powder A accounted for 50% by mass and powder C accounted for 50% by mass in the mixture of powder A and powder C. Clinker powder was obtained in the same manner as in Example 1, except that calcination material mixture 3 was used instead of calcination material mixture 1. After that, free lime measurement and powder X-ray diffraction were performed. [Example 6] Clinker powder was obtained in the same manner as in Example 2, except that calcination material mixture 3 was used instead of calcination material mixture 1, and the temperature was maintained at 1,000°C for 30 minutes in a box-type electric furnace, then the temperature was increased at a heating rate of 20°C / min to 1,250°C, and then maintained at 1,250°C for 30 minutes. After that, free lime measurement and powder X-ray diffraction were performed.

[0048] [Example 7] A mixture of firing materials 4 was prepared by mixing powder B derived from a cement hydrate-containing substance and powder D derived from a cement hydrate-containing substance in amounts such that powder B accounted for 50% by mass and powder D accounted for 50% by mass in the mixture of powder B and powder D. Clinker powder was obtained in the same manner as in Example 1, except that calcination material mixture 4 was used instead of calcination material mixture 1. After that, free lime measurement and powder X-ray diffraction were performed. [Example 8] Clinker powder was obtained in the same manner as in Example 2, except that calcination material mixture 4 was used instead of calcination material mixture 1, and the temperature was maintained at 1,000°C for 30 minutes in a box-type electric furnace, then the temperature was raised at a heating rate of 20°C / min to 1,250°C, and then maintained at 1,250°C for 30 minutes. After that, free lime measurement and powder X-ray diffraction were performed.

[0049] [Example 9] The firing material mixture 5 consisted solely of powder E derived from cement hydrate-containing material. Clinker powder was obtained in the same manner as in Example 1, except that calcination material mixture 5 was used instead of calcination material mixture 1. After that, free lime measurement and powder X-ray diffraction were performed. [Example 10] Clinker powder was obtained in the same manner as in Example 2, except that calcination material mixture 5 was used instead of calcination material mixture 1, and the temperature was maintained at 1,000°C for 30 minutes in a box-type electric furnace, then the temperature was increased at a heating rate of 20°C / min to 1,300°C, and then maintained at 1,300°C for 30 minutes. After that, free lime measurement and powder X-ray diffraction were performed.

[0050] [Comparative Example 1] A mixture consisting solely of powder F was designated as the calcination material mixture 6. Clinker powder was obtained in the same manner as in Example 2, except that calcination material mixture 6 was used instead of calcination material mixture 1. After that, free lime measurement and powder X-ray diffraction were performed. [Comparative Example 2] Clinker powder was obtained in the same manner as in Example 2, except that calcination material mixture 6 was used instead of calcination material mixture 1, and the temperature was maintained at 1,000°C for 30 minutes in a box-type electric furnace, then the temperature was raised at a heating rate of 20°C / min to 1,250°C, and then maintained at 1,250°C for 30 minutes. After that, free lime measurement and powder X-ray diffraction were performed. [Comparative Example 3] Clinker powder was obtained in the same manner as in Example 2, except that calcination material mixture 6 was used instead of calcination material mixture 1, and the temperature was maintained at 1,000°C for 30 minutes in a box-type electric furnace, then the temperature was increased at a heating rate of 20°C / min to 1,300°C, and then maintained at 1,300°C for 30 minutes. After that, free lime measurement and powder X-ray diffraction were performed. Table 5 shows the chemical composition of each clinker powder. Table 6 shows the measurement results for free lime.

[0051] [Table 5]

[0052] [Table 6]

[0053] Table 4 shows that while the free lime content of the clinker powder in Comparative Example 1 (fired at a firing temperature of 1,200°C) was 9.5% by mass, in Examples 1, 3, 5, 7, and 9, the free lime content of the clinker powder was 0-7.0% by mass, even though the firing temperature (1,000°C) was lower than that of Comparative Example 1. In particular, the free lime content in Examples 1 and 3 was 0% by mass, which is extremely low. From this, it can be seen that the clinker powder of the present invention has a low free lime content (excellent strength development) even at lower firing temperatures.

Claims

1. A method for producing clinker powder consisting of a calcined product of a calcination material containing cement hydrate powder, A powder preparation step involves obtaining a cement hydrate-containing powder from one or more cement hydrate-containing materials by one or more operations including at least one powdering operation consisting of crushing or grinding, and then preparing a firing material containing the above cement hydrate-containing powder. A firing process in which the above firing material is fired at 950 to 1,100°C to obtain clinker, A grinding step to obtain the above clinker powder by grinding the above clinker, Includes, The above clinker powder has a water hardness (H.M.) of 0.2 to 1.5, a silicate content (S.M.) of 1.5 to 3.3, an iron content (I.M.) of 1.7 to 3.5, and aluminum oxide (Al ２ O ３ ) and iron oxide (Fe ２ O ３ A method for producing clinker powder, characterized by having a mineral composition in which the total content of ) is 7 to 18% by mass.

2. A method for producing clinker powder consisting of a calcined product of a calcination material containing cement hydrate powder, A powder preparation step to obtain two or more types of firing materials by obtaining cement hydrate-containing powder from each of two or more types of cement hydrate-containing materials through one or more operations including at least one operation of pulverization consisting of crushing or grinding, and then preparing firing materials containing the above cement hydrate-containing powder, A firing process to obtain two or more clinkers by firing each of the two or more of the above firing materials at 950 to 1,100°C (however, the firing temperatures of the two or more of the above firing materials may be the same or different from each other), The above two or more types of clinker are crushed and then mixed to obtain the above clinker powder, or the above two or more types of clinker are mixed and then crushed to obtain the above clinker powder, crushing and mixing process, Includes, The above clinker powder has a water hardness (H.M.) of 0.2 to 1.5, a silicate content (S.M.) of 1.5 to 3.3, an iron content (I.M.) of 1.7 to 3.5, and aluminum oxide (Al ２ O ３ ) and iron oxide (Fe ２ O ３ A method for producing clinker powder, characterized by having a mineral composition in which the total content of ) is 7 to 18% by mass.

3. A method for producing clinker powder according to claim 1 or 2, wherein the total alkali content of the above-mentioned clinker powder is 4.0% by mass or less.

4. A method for producing clinker powder according to claim 1 or 2, wherein the free lime (f-CaO) content of the above clinker powder is 8% by mass or less.

5. A method for producing clinker powder according to claim 1 or 2, wherein the cement hydrate-containing material is concrete or mortar, and in the powder preparation step, at least one of crushing and coarse crushing is performed on the cement hydrate-containing material, and then a portion of the aggregate is recovered to obtain a coarse crushed material from which a portion of the aggregate has been removed, and then the powdering operation is performed on the coarse crushed material.

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