JP7769564B2 - Cement composition and method for producing cement composition - Google Patents

Description

The present disclosure relates to a cement composition and a method for producing a cement composition.

As part of efforts to promote low-carbon society, cement compositions are being used in which a portion of ordinary Portland cement, which has a large _CO2 emission associated with its production, is replaced with admixtures. Limestone is widely used as an admixture to be added to cement because it is readily available and inexpensive. Currently, the amount of admixture to be added to ordinary Portland cement is stipulated by JIS standards as 5% by mass or less.

However, from the perspective of preventing global warming and achieving low carbon emissions, it is desirable to further increase the proportion of cement clinker replaced with admixtures in order to reduce the amount of cement clinker used. For example, Non-Patent Document 1 investigates the mixing of admixture amounts in excess of the 5% by mass specified by the JIS standard. However, it has been shown that increasing the amount of limestone added to 10% by mass results in a decrease in both early and long-term compressive strength.

Furthermore, attempts have been made to reduce the total _CO2 emissions during the production of cement compositions by using components that can be used from waste materials and industrial by-products in addition to limestone, a natural resource. Such components include industrial by-products such as fly ash, blast furnace slag, and silica fume.

Fly ash is a by-product emitted from coal-fired power plants and is known to have pozzolanic activity. Cement compositions incorporating fly ash are widely used because they can provide hardened bodies that exhibit excellent durability and strength upon hardening.

In addition to the industrial by-products already in use, as mentioned above, new materials that can be used as admixtures are being explored. If other waste materials could be used as admixtures in cement compositions, it would be possible to further reduce the environmental impact and expand the range of admixture options depending on the intended use of the cement composition, thereby contributing to the creation of a recycling-oriented society. An example of waste that has not yet seen much practical use as an admixture is waste FCC catalyst. While waste FCC catalyst has been used as a fine aggregate with a relatively large particle size, its use as an admixture has not been fully investigated (see, for example, Patent Document 1).

JP 2017-122550 A

Ayuka Nakaguchi et al., "Quality Evaluation of Cement with Increased Amounts of Minor Mixture Components," Abstracts of the Cement Technology Conference, 2018, pp. 270-271

According to the inventors' investigations, when limestone is partially replaced with spent FCC catalyst, the compressive strength of the hardened body obtained by hardening the cement composition may not be sufficient.

The purpose of this disclosure is to provide a cement composition and a method for producing the same that can contribute to reducing environmental impact by using waste FCC catalyst as an admixture and exhibit excellent early compressive strength.

One aspect of the present disclosure provides a cement composition comprising cement clinker, gypsum, and a spent FCC catalyst, wherein the spent FCC catalyst has a Blaine specific surface area of 4000 cm ² /g or more.

The above cement composition uses waste FCC catalyst as an admixture, which can contribute to reducing the environmental impact, and by using waste FCC catalyst with a specified Blaine specific surface area, it can exhibit excellent early compressive strength.

The spent FCC catalyst may have an insoluble residue in hydrochloric acid of 85% by mass or less and an R ₂ O content of 0.70% by mass or less.

The above-mentioned waste FCC catalyst may be acid-treated, alkali-treated, or heat-treated. When the waste FCC catalyst has undergone acid or alkali treatment, metals that inhibit the pozzolanic reaction are reduced, and the initial compressive strength can be further improved. Furthermore, when the waste FCC catalyst is heat-treated, the crystalline state of any clay minerals that may remain in the waste FCC catalyst is changed to an amorphous state, which contributes to promoting the pozzolanic reaction and can further improve the initial compressive strength.

The cement composition further contains limestone, and the total amount of the spent FCC catalyst and the limestone is more than 5.0 mass% and not more than 30.0 mass%, and the content of the spent FCC catalyst may be 0.1 to 90 mass% based on the total amount of the spent FCC catalyst and the limestone. By including limestone (calcium carbonate) in the cement composition, it is possible to further increase the cement clinker replacement rate, which is preferable from the perspective of reducing the environmental load. Furthermore, by including a specified amount of limestone, the reactivity of the cement clinker can be improved, and the initial compressive strength can be further improved.

One aspect of the present disclosure provides a method for producing a cement composition, comprising: a step of adjusting the particle size of a spent FCC catalyst to make the Blaine specific surface area of the spent FCC catalyst 4000 cm ² /g or more; and a step of mixing the spent FCC catalyst with cement clinker and gypsum.

The above-mentioned cement composition manufacturing method, which incorporates a waste FCC catalyst, can produce a cement composition that can contribute to reducing environmental impact. Furthermore, since the above-mentioned manufacturing method includes a step of adjusting the particle size of the waste FCC catalyst so that the Blaine specific surface area is equal to or greater than a predetermined value, the resulting cement composition can exhibit excellent early compressive strength.

The method may further include a step of subjecting the waste FCC catalyst to at least one treatment selected from the group consisting of acid treatment, alkali treatment, and heat treatment.

This disclosure provides a cement composition and a method for producing the same that can contribute to reducing environmental impact by using waste materials as admixtures and exhibit excellent early compressive strength.

Embodiments of the present disclosure are described below. However, the following embodiments are merely examples for explaining the present disclosure, and are not intended to limit the present disclosure to the following content. In the following description, when it is stated as "X to Y" (X and Y are arbitrary numbers), it means "X or greater and Y or less" unless otherwise specified.

Unless otherwise specified, the materials exemplified in this specification can be used alone or in combination of two or more. When multiple substances corresponding to each component are present in the composition, the content of each component in the composition refers to the total amount of those multiple substances present in the composition, unless otherwise specified.

One embodiment of the cement composition according to the present disclosure comprises cement clinker, gypsum, and a spent FCC catalyst. In this way, the cement composition uses a spent FCC catalyst as a partial substitute for cement clinker, making it beneficial as a cement composition that reduces environmental impact.

Examples of cement clinker include ordinary cement clinker, early-strength cement clinker, moderate-heat cement clinker, low-heat cement clinker, and oil-well cement clinker. From the standpoint of ease of availability and further improving early-age strength, the cement preferably contains at least one of ordinary Portland cement and early-strength Portland cement, more preferably ordinary Portland cement, and may be ordinary Portland cement.

Cement clinker contains _C3S , _C2S , _C3A , and _C4AF . The contents of _C3S , _C2S , _C3A , and _C4AF can be calculated using the Bogue formula. The Bogue formula is a widely used formula for calculating the contents of major minerals in cement clinker from the content ratios of their chemical compositions. The Bogue formula shown below can be used to calculate the contents of tricalcium silicate ( _3CaO ·SiO2 _, C3S), dicalcium silicate (2CaO·SiO2 _{, C2S} ), tricalcium aluminate (3CaO· _{Al2O3 , C3A} ), tricalcium aluminate (3CaO· _Al2O3 , _C3A ), and tetracalcium aluminoferrate (4CaO· _Al2O3 · _{Fe2O3 , C4AF )} in cement clinker. The chemical formulas represent the content ratios (mass _% ) of each compound indicated by chemical analysis values according to JIS R 5204:2019 "Method for X-ray fluorescence analysis of cement."

<Bogue style>
C ₃ S [mass %] = (4.07 x CaO [mass %]) - (7.60 x SiO ₂ [mass %]) - (6.72 x Al ₂ O ₃ [mass %]) - (1.43 x Fe ₂ O ₃ [mass %]) - (2.85 x SO ₃ [mass %])
C ₂ S [mass %] = (2.87 x SiO ₂ [mass %]) - (0.754 x C ₃ S [mass %])
C ₃ A [mass %] = (2.65 x Al ₂ O ₃ [mass %]) - (1.69 x Fe ₂ O ₃ [mass %])
C ₄ AF [mass%] = 3.04 x Fe ₂ O ₃ [mass%]

The _C3S content in cement clinker is preferably 30.0 to 70.0 mass%, more preferably 40.0 to 65.0 mass%, even more preferably 45.0 to 60.0 mass%, even more preferably 50.0 to 55.0 mass%, and particularly preferably 52.0 to 53.0 mass%. By setting the lower limit of the _C3S content within the above range, the early strength of the cement composition upon hardening can be further improved. Furthermore, by setting the upper limit of the _C3S content within the above range, heat generation upon hardening of the cement composition can be suppressed.

The _C2S content in cement clinker is preferably 5.0 to 65.0 mass%, more preferably 10.0 to 50.0 mass%, even more preferably 15.0 to 40.0 mass%, even more preferably 20.0 to 30.0 mass%, and particularly preferably 23.0 to 25.0 mass%. By setting the lower limit of the _C2S content within the above range, the long-term strength of the cement composition upon hardening can be further improved. Also, by setting the upper limit of the _C2S content within the above range, the early strength of the cement composition upon hardening can be further improved.

The lower limit of the _C3A content in the cement clinker is preferably 7.0% by mass or more, more preferably 8.0% by mass or more, even more preferably 9.0% by mass or more, even more preferably 10.0% by mass or more, and particularly preferably 10.3% by mass or more. By setting the lower limit of the _C3A content within the above range, a cement composition can be produced in which the amount of waste and by-products such as coal ash used as the cement clinker raw material is increased. The upper limit of the _C3A content in the cement clinker is preferably 13.0% by mass or less, more preferably 12.0% by mass or less, even more preferably 11.0% by mass _or less, even more preferably 10.8% by mass, and particularly preferably 10.5% by _mass or _less . Setting the upper limit of the _C3A content within the above range can suppress the regeneration of ettringite (a compound represented by _{3CaO.Al2O3.3CaSO4.32H2O} ) and further reduce the increase in adiabatic temperature rise during hardening of the cement composition.

The lower limit of the _C4AF content in the cement clinker is preferably 7.0% by mass or more, more preferably 8.0% by mass or more, even more preferably 9.0% by mass or more, even more preferably 9.5% by mass or more, and particularly preferably 9.8% by mass or more. By setting the lower limit of the _C4AF content within the above range, it is possible to produce a cement composition that increases the amount of waste and by-products, such as coal ash, used as the cement clinker raw material. The upper limit of the _C4AF content in the cement clinker is preferably 14.0% by mass or less, more preferably 12.0% by mass or less, even more preferably 11.0% by mass or less, even more preferably 10.5% by mass or less, and particularly preferably 10.0% by mass or less. Setting the upper limit of the _C4AF content within the above range can further reduce the increase in adiabatic temperature rise during hardening of the cement composition.

The cement clinker content may be, for example, 70 to 95 mass%, 75 to 93 mass%, or 85 to 90 mass%, with the total amount of the cement composition being 100 mass%.

Examples of gypsum that can be used include gypsum dihydrate, gypsum hemihydrate, and anhydrous gypsum. One type of gypsum may be used alone, or multiple types may be used in combination. The gypsum content in the cement composition may be the same as the gypsum content in general Portland cement.

The content of gypsum in the cement composition may be, for example, 0.5 to 3.5 mass%, 0.7 to 2.5 mass%, or 0.9 to 1.2 mass%, calculated as SO ₃ , with the total amount of the cement composition being 100 mass%.

The term "spent FCC catalyst" used in this specification refers to a catalyst that has been used as an FCC catalyst, a catalyst used in fluid catalytic cracking (FCC) in petroleum refining, and can be referred to as a used FCC catalyst. The FCC catalyst may be, for example, a spherical powder composed of a substrate made of alumina, silica, kaolin, etc., and zeolite on the substrate. The zeolite contained in the FCC catalyst performs ion exchange functions. The distribution of the zeolite on the substrate may be adjusted as appropriate. The spherical powder of the FCC catalyst may be adjusted to a relatively small particle size to improve catalytic activity. The spent FCC catalyst may be, for example, an FCC catalyst used for cracking large molecular weight residual oil or as a metal trapping agent for V, Ni, etc., during the process of fractionating low-grade heavy feedstock oil into gasoline and LCO.

The lower limit of the Blaine specific surface area of the spent FCC catalyst is 4000 cm ² /g or more, but may be, for example, 5000 cm ² /g or more, 8000 cm ² /g or more, or 10000 cm ² /g or more. When the lower limit of the Blaine specific surface area is within the above range, excellent early compressive strength can be exhibited. The upper limit of the Blaine specific surface area of the spent FCC catalyst may be, for example, 50000 cm ² /g or less, 30000 cm ² /g or less, 20000 cm ² /g or less, or 15000 cm ² /g or less. When the upper limit of the Blaine specific surface area is within the above range, energy consumption associated with particle size adjustment and CO ₂ emissions during production of the cement composition can be further reduced. The Blaine specific surface area of the spent FCC catalyst may be adjusted within the above range, and may be, for example, 4000 to 30000 cm ² /g. The Blaine specific surface area of commonly available spent FCC catalysts is about 1000 to 3000 cm ² /g, and can be controlled by adjusting the particle size by pulverization, classification, or the like.

In this specification, "Blaine specific surface area" refers to a value measured in accordance with the method described in JIS R 5201:2015, "Physical Testing Methods for Cement." Here, the density value used when measuring the Blaine specific surface area of spent FCC catalyst is a value measured using an automatic wet true density measuring device using the liquid-phase displacement method (pycnometer method) in ethanol.

The lower limit of the average particle size of the spent FCC catalyst may be, for example, 3 μm or more, 8 μm or more, 10 μm or more, or 13 μm or more. When the lower limit of the average particle size is within the above range, energy consumption associated with particle size adjustment and _CO2 emissions during production of the cement composition can be further reduced. The upper limit of the average particle size of the spent FCC catalyst may be, for example, 50 μm or less, 40 μm or less, 30 μm or less, 26 μm or less, or 18 μm or less. When the upper limit of the average particle size is within the above range, excellent early compressive strength can be exhibited. The average particle size of the spent FCC catalyst may be adjusted within the above range, and may be, for example, 3 to 50 μm or 8 to 18 μm.

In this specification, "average particle size" refers to a value measured using a laser diffraction/scattering method. Ethanol is used as the dispersion medium, and the measurement is performed with the spent FCC catalyst dispersed in the ethanol.

The lower the amount of insoluble residue (insol) in hydrochloric acid in the spent FCC catalyst, the lower the amount of crystalline material (such as quartz) that does not contribute to the reaction of the spent FCC catalyst in the cement composition, resulting in superior reactivity. The upper limit of the insol content of the spent FCC catalyst may be, for example, 90% by mass or less, 85% by mass or less, 83% by mass or less, 80% by mass or less, or 76% by mass or less. By ensuring that the upper limit of the insol content of the spent FCC catalyst is within the above range, the spent FCC catalyst will have superior reactivity, and the initial compressive strength of the cement composition when hardened will be better. The lower limit of the insol content of the spent FCC catalyst is not particularly limited, but may be, for example, 20% by mass or more, 40% by mass or more, or 60% by mass or more.

In this specification, the amount of acid-insoluble residue in spent FCC catalyst refers to the value measured in accordance with the method specified in JIS R 5202:2010 "Methods for Chemical Analysis of Cement."

The waste FCC catalyst used in the above manufacturing method may be, for example, a water-washed product, an acid-treated product, an alkali-treated product, or a heat-treated product. Because waste FCC catalysts are used in petroleum refining, they may contain residues (e.g., alkali metals, alkaline earth metals, heavy metals other than alkali metals and alkaline earth metals, and clay mineral residues). Therefore, water washing, acid treatment, and alkali treatment can reduce the content of these residues. This reduces factors that inhibit the reaction of the waste FCC catalyst, thereby accelerating the hardening reaction of the cement composition and improving the compressive strength of the resulting hardened body. Furthermore, the reactivity of clay minerals and other residues varies depending on their crystalline state. Therefore, heat treatment can change the crystalline state of the clay minerals, converting them to an amorphous state that is more conducive to reaction, thereby accelerating the hardening reaction of the cement composition and improving the compressive strength of the resulting hardened body.

The spent FCC catalyst may contain an alkali metal. Examples of alkali metals contained in the spent FCC catalyst include sodium (Na) and potassium (K). The upper limit of the total alkali content (R ₂ O content) in the spent FCC catalyst may be, for example, 1.50 mass% or less, 1.00 mass% or less, 0.70 mass% or less, 0.60 mass% or less, 0.50 mass% or less, or 0.30 mass% or less. When the upper limit of the R ₂ O content is within the above range, the initial compressive strength when the cement composition is hardened can be further improved. The lower limit of the total alkali content in the spent FCC catalyst is not particularly limited, but may be, for example, 0.10 mass% or more, or 0.20 mass% or more.

The total alkali amount (R ₂ O amount) in this specification means the total amount of sodium and potassium contained in the spent FCC catalyst in terms of oxides. More specifically, it is a value calculated by the following formula (1).
R ₂ O [mass %] = Na ₂ O [mass %] + 0.658×K ₂ O amount [mass %] ... Formula (1)

The spent FCC catalyst may have an insoluble residue in hydrochloric acid of 90% by mass or less and an R ₂ O content of 1.50% by mass or less, or may have an insoluble residue in hydrochloric acid of 85% by mass or less and an R ₂ O content of 0.70% by mass or less.

The spent FCC catalyst may contain heavy metals other than alkali metals and alkaline earth metals. Examples of heavy metals in the spent FCC catalyst include vanadium (V), chromium (Cr), molybdenum (Mo), nickel (Ni), copper (Cu), zinc (Zn), cadmium (Cd), mercury (Hg), lead (Pb), arsenic (As), bismuth (Bi), and selenium (Se).

The upper limit of the total content of heavy metals other than alkali metals and alkaline earth metals in the spent FCC catalyst may be, for example, 8000 ppm or less, 3000 ppm or less, 1000 ppm or less, or 500 ppm or less. By ensuring that the upper limit of the total content of the above-mentioned heavy metals is within the above range, the initial compressive strength of the cement composition when hardened can be further improved. The lower limit of the total content of heavy metals other than alkali metals and alkaline earth metals in the spent FCC catalyst is not particularly limited, but may be, for example, 50 ppm or more, or 200 ppm or more. The total content of heavy metals other than alkali metals and alkaline earth metals in the spent FCC catalyst may be adjusted within the above range, and may be, for example, 50 to 3000 ppm, or 200 to 1000 ppm.

The spent FCC catalyst may contain crystalline minerals in the substrate, and the crystalline state can be confirmed by X-ray diffraction. Specific examples of crystalline minerals include zeolite, alumina (Al ₂ O ₃ ), quartz (SiO ₂ ), anorthite (CaAl ₂ Si ₂ O ₈ ), kaolin (Al ₄ Si ₄ O ₁₀ (OH) ₈ ), muscovite (KAl ₂ AlSi ₃ O ₁₀ (OH,F) ₂ ), and titanium dioxide (TiO ₂ ). Furthermore, the mass ratio of the amorphous and crystalline minerals can be quantified by adding an internal standard substance and performing X-ray measurement and Rietveld analysis. The zeolite content in the spent FCC catalyst may be, for example, about 10 to 90 mass%, about 20 to 80 mass%, or about 40 to 70 mass%.

From the viewpoint of strength development, it is preferable to use a spent FCC catalyst adjusted to have a low silicon dioxide content (SiO ₂ content). The upper limit of the SiO ₂ content in the spent FCC catalyst may be, for example, 85 mass% or less, 75 mass% or less, 65 mass% or less, or 55 mass% or less. From the viewpoint of effective utilization of waste and by-products, particularly effective utilization of spent FCC catalyst, it is preferable to use a powder with a high silicon dioxide content (SiO ₂ content). The lower limit of the SiO ₂ content in the spent FCC catalyst may be, for example, 25 mass% or more, 35 mass% or more, or 45 mass% or more.

From the viewpoint of strength development, it is preferable to use a spent FCC catalyst whose aluminum oxide content (Al ₂ O ₃ content) is adjusted to be low. The upper limit of the Al ₂ O ₃ content in the spent FCC catalyst may be, for example, 65 mass% or less, 55 mass% or less, or 45 mass% or less. From the viewpoint of effective utilization of waste and by-products, it is preferable to use a powder whose aluminum oxide content (Al ₂ O ₃ content) is high. The lower limit of the Al ₂ O ₃ content in the spent FCC catalyst may be 5 mass% or more, 15 mass% or more, 25 mass% or more, or 35 mass% or more.

The spent FCC catalyst may be composed solely of inorganic components, or may contain organic components to the extent that the effects of the present disclosure are not impaired. Examples of such organic components include unburned carbon.

The lower limit of the content of the spent FCC catalyst in the above-described cement composition may be, for example, 0.1% by mass or more, 0.5% by mass or more, 1.0% by mass or more, 1.5% by mass or more, or 3.0% by mass or more, relative to the total amount of the cement composition. By ensuring that the lower limit of the spent FCC catalyst content is within the above range, the cement composition can exhibit better early strength when hardened. The upper limit of the spent FCC catalyst content in the above-described cement composition may be, for example, 30% by mass or less, 20% by mass or less, 15% by mass or less, or 10% by mass or less, relative to the total amount of the cement composition. By ensuring that the upper limit of the spent FCC catalyst content is within the above range, the setting of the cement composition is not delayed when hardened, and more appropriate early hardening characteristics are obtained. The content of the spent FCC catalyst may be adjusted within the above-described range, and may be, for example, 0.5 to 15% by mass, 1.0 to 20% by mass, or 3.0 to 10% by mass, relative to the total amount of the cement composition.

The content of spent FCC catalyst is an estimated value determined using the following method. For a cement composition to which an internal standard has been added, the peak profile is measured by X-ray diffraction, and Rietveld analysis is performed to quantify the mass ratio of amorphous and crystalline minerals. The cement clinker, gypsum, and other crystalline components (limestone, etc.) not derived from the spent FCC catalyst in the cement composition are subtracted to calculate the amount of crystalline and amorphous components derived from the spent FCC catalyst, and the estimated content is determined. Note that if you prepare your own cement composition, the content of spent FCC catalyst will match the blending amount, so the analysis described above is not required.

The cement composition according to the present disclosure may further contain limestone. In this case, the cement composition contains the above-mentioned waste FCC catalyst and limestone as the main components of the admixture. For example, commonly available limestone, limestone powder, and limestone powder, which are primarily composed of calcium carbonate, can be used as the limestone. The limestone preferably conforms to the minor admixture components specified in JIS R 5210:2019 "Portland Cement."

The lower limit of the total amount (total content) of the limestone and the spent FCC catalyst may be, for example, more than 5.0 mass%, 7.0 mass% or more, 8.0 mass% or more, or 9.0 mass% or more, based on the total amount of the cement composition. When the lower limit of the total amount of the limestone and the spent FCC catalyst is within the above range, _CO2 emissions during production of the cement composition can be further reduced. The upper limit of the total content of the limestone and the spent FCC catalyst may be, for example, 30.0 mass% or less, 20.0 mass% or less, 15.0 mass% or less, 12.0 mass% or less, or 10.0 mass% or less, based on the total amount of the cement composition. When the upper limit of the total amount of the limestone and the spent FCC catalyst is within the above range, the cement composition can exhibit better compressive strength when hardened. The total amount of the limestone and the spent FCC catalyst may be adjusted within the above-mentioned range, and may be, for example, more than 5.0 mass% and not more than 30.0 mass%, or 7.0 to 15.0 mass%, based on the total amount of the cement composition.

In the above-described cement composition, the content of the spent FCC catalyst is 0.1 to 90% by mass, based on the total amount of the limestone and the spent FCC catalyst. The lower limit of the spent FCC catalyst content may be, for example, 5.0% by mass or more, 15.0% by mass or more, 25.0% by mass or more, 30.0% by mass or more, or 40.0% by mass or more, based on the total amount of the limestone and the spent FCC catalyst. The upper limit of the spent FCC catalyst content may be, for example, 80.0% by mass or less, 70.0% by mass or less, or 60.0% by mass or less, based on the total amount of the limestone and the spent FCC catalyst.

In addition to cement clinker, gypsum, and spent FCC catalyst, the cement composition may contain other components in addition to the limestone described above, as long as the scope of the present disclosure is not impaired. Examples of other components include calcium hydroxide, silica powder, other calcium-containing powders (excluding gypsum, limestone, and the spent FCC catalyst described above), concrete water reducers, accelerators, and retarders.

The above-mentioned cement composition can be produced, for example, by the following method: One embodiment of the method for producing a cement composition includes a step of adjusting the particle size of a spent FCC catalyst to make the Blaine specific surface area of the spent FCC catalyst 4000 cm ² /g or more (particle size adjusting step), and a step of mixing the spent FCC catalyst with cement clinker and gypsum (mixing step).

The particle size adjusting step is a step of adjusting the particle size of the spent FCC catalyst. The particle size of the spent FCC catalyst can be adjusted, for example, by pulverization using a ball mill, a vertical roller mill, a roller press, etc., or by classification using a classifier, a sieve, etc. Note that, when a spent FCC catalyst that has been separately adjusted to have a Blaine specific surface area of 4000 cm ² /g or more is available as the spent FCC catalyst, the particle size adjusting step may be omitted by using this.

In the mixing process, cement clinker and cement are mixed with the above-mentioned spent FCC catalyst. In addition to mixing the various components, the various components may also be crushed during the mixing process. The order of mixing and crushing is not particularly limited. That is, the various components may be mixed and then crushed, or they may be crushed and then mixed, or the various components may be mixed and crushed simultaneously. The various components may be mixed in the mixing process using a mixer such as a pan mixer, tilting mixer, or ribbon mixer. They may also be mixed and crushed using a crusher such as a ball mill, vertical roller mill, or roller press. Alternatively, each main component may be crushed separately and then mixed using a mixer such as a mechanical mixer.

The above-described manufacturing method may include other processes in addition to the particle size adjustment process and the mixing process. Such other processes may include at least one process of treating the waste FCC catalyst with water, acid, alkali, and heat. The water, acid, alkali, and heat treatment processes are also referred to as the water treatment process, acid treatment process, alkali treatment process, and heat treatment process, respectively, and the waste FCC catalysts that have undergone these processes are also referred to as the water-treated product, acid-treated product, alkali-treated product, and heat-treated product, respectively. The process of treating the waste FCC catalyst with at least one process of treating the waste FCC catalyst with acid, alkali, and heat may be performed before or after the particle size adjustment process.

The acid treatment step is carried out by bringing the spent FCC catalyst into contact with a solution containing an acid. The contact method is not particularly limited, and may be, for example, by immersing the spent FCC catalyst in the solution. Examples of acids that can be used include inorganic acids such as hydrochloric acid or hydrogen chloride (HCl), sulfuric acid, nitric acid, phosphoric acid, acetic acid, and formic acid. The solution may be an aqueous solution. When an aqueous solution is used, the pH of the aqueous solution may be, for example, 0.1 to 6.0, 0.5 to 4.0, or 1.0 to 3.0. The concentration of the solution may be, for example, 1.0×10 ⁻⁶ mol/L to 10.0 mol/L, or 1.0×10 ⁻³ mol/L to 1.0 mol/L.

The acid treatment step is carried out by blending, for example, 5 to 10,000 parts by mass, 10 to 1,000 parts by mass, or 25 to 100 parts by mass of the acid-containing solution per 100 parts by mass of the spent FCC catalyst. The acid-containing solution used in the acid treatment step may be heated, for example, to 30 to 90°C or 50 to 70°C. The acid treatment time in the acid treatment step may be, for example, 30 minutes to 3 days, or 1 hour to 1 day.

The alkali treatment step is carried out by bringing the spent FCC catalyst into contact with a solution containing an alkali. The contact method is not particularly limited, and may be, for example, by immersing the spent FCC catalyst in the solution. Examples of alkali that can be used include sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, magnesium hydroxide, sodium carbonate, and potassium carbonate. The solution may be an aqueous solution. When an aqueous solution is used, the pH of the aqueous solution may be, for example, 8.0 to 15.0, 9.0 to 14.0, or 10.0 to 13.0. The concentration of the solution may be, for example, 1.0 × 10 ^-6 mol/L to 10.0 mol/L, or 1.0 × 10 ^-3 mol/L to 1.0 mol/L.

The alkali treatment step is carried out by blending, for example, 5 to 10,000 parts by mass, 10 to 1,000 parts by mass, or 25 to 100 parts by mass of the alkali-containing solution per 100 parts by mass of the spent FCC catalyst. The alkali-containing solution used in the alkali treatment step may be heated, for example, to 30 to 90°C or 50 to 70°C. The alkali treatment time in the alkali treatment step may be, for example, 30 minutes to 3 days, or 1 hour to 1 day.

When the acid treatment process and alkali treatment process are performed, washing with water and drying can also be carried out after the treatment in order to remove the acid and alkali from the spent FCC catalyst.

The heat treatment process is a process in which the spent FCC catalyst is heat-treated at a temperature of 200°C or higher. The heating temperature may be, for example, 200 to 1500°C, 300 to 1200°C, or 500 to 1000°C. The heating time of the spent FCC catalyst in the heat treatment process may be, for example, 5 minutes to 3 hours, 10 minutes to 2 hours, or 30 minutes to 1 hour. In this specification, the heating time refers to the retention time during which the environmental temperature around the spent FCC catalyst is maintained at the desired heating temperature after it has reached that temperature.

The cement composition produced by the above-mentioned production method can be used by mixing it with, for example, fine aggregate, coarse aggregate, water, and admixtures, and can also be used to produce a mortar composition or concrete composition that gives a hardened product (mortar or concrete).

The fine aggregate specified in JIS A 5005:2020 "Crushed Stone and Crushed Sand for Concrete" can be used. Examples of fine aggregate include river sand, land sand, sea sand, crushed sand, silica sand, copper slag fine aggregate, and electric furnace oxidizing slag fine aggregate. When fine aggregate is used, the amount of fine aggregate used may be, for example, 50 to 500 parts by mass, 100 to 300 parts by mass, or 200 to 250 parts by mass per 100 parts by mass of the above-mentioned cement composition.

The coarse aggregate specified in JIS A 5005:2020 "Crushed stone and crushed sand for concrete" can be used. Examples of coarse aggregate include gravel and crushed stone. When using coarse aggregate, the amount of coarse aggregate used may be, for example, 50 to 500 parts by mass, 100 to 300 parts by mass, or 200 to 250 parts by mass per 100 parts by mass of the above-mentioned cement composition.

Fine aggregate and coarse aggregate can also be used in combination. In this case, the total amount of fine aggregate and coarse aggregate used may be 100 to 300 parts by mass, or 200 to 250 parts by mass, per 100 parts by mass of the above-mentioned cement composition.

Examples of water include tap water, distilled water, and deionized water. The amount of water used may be 20 to 100 parts by weight, or 40 to 70 parts by weight, per 100 parts by weight of the above-mentioned cement composition.

Examples of admixtures include air-entraining agents, water-reducing agents, air-entraining and water-reducing agents, high-performance water-reducing agents, superplasticizers, antifoaming agents, shrinkage-reducing agents, set accelerators, set retarders, and thickeners. The amount of admixture used may be, for example, 0.01 to 2 parts by mass per 100 parts by mass of the above-mentioned cement composition.

Although several embodiments have been described above, the present disclosure is in no way limited to the above embodiments. Furthermore, the descriptions of the above embodiments can be mutually applied.

The present disclosure will be explained in more detail below with reference to examples, comparative examples, and reference examples. However, the present disclosure is not limited to the following examples.

[Raw materials for cement composition]
The following materials were used as raw materials for the cement composition.

(cement clinker)
The cement clinker used was ordinary Portland cement clinker whose mineral composition according to the Bogue formula is shown in the following Table 1. The chemical composition of the cement used in the calculations according to the Bogue formula was measured in accordance with the method described in JIS R 5204 "Method for X-ray fluorescence analysis of cement."

(plaster)
The gypsum used was gypsum that satisfied the requirements described in JIS R 9151:2009 "Natural gypsum for cement."

(mixed material)
The admixtures used were limestone, waste FCC catalyst, and fly ash, as described below. Table 2 shows the chemical composition, average particle size, and Blaine specific surface area of the admixtures.

Limestone (LS) has a calcium carbonate content of 90% by mass or more and an aluminum oxide content of 1.0% by mass or less, and is a fine powder of limestone obtained by pulverizing limestone that satisfies the requirements for minor mixed components described in JIS R 5210:2019 "Portland cement".

Waste FCC Catalysts: Four types of untreated waste FCC catalysts (FC1 to FC4) with different chemical components and catalysts that had undergone any of the treatments (A) to (D) described below were used as waste FCC catalysts. The average particle diameters of the untreated waste FCC catalysts FC1 to FC4 were 67 μm, 70 μm, 59 μm, and 63 μm, respectively. The average particle diameters were measured using a laser diffraction/scattering particle size distribution analyzer (manufactured by Horiba, Ltd., product name: LA-950V2). Specifically, particles were dispersed in ethanol in advance by ultrasonic treatment, and then the particle diameters in ethanol were measured. Measurements were performed twice for each sample, and the median diameter was calculated on a volume basis for each. The arithmetic mean of the calculated median diameters was taken as the average particle diameter.

(A) Pulverization step The waste FCC catalysts FC1-A and FC2-A were prepared by pulverizing the waste FCC catalysts FC1 and FC2 in a ball mill for 15 minutes to increase the Blaine specific surface area. The average particle diameters of the waste FCC catalysts FC1-A and FC2-A were 31 μm and 25 μm, respectively.

(B) Acid Treatment Step Waste FCC catalysts FC1-B and FC2-B are acid-treated products of the waste FCC catalysts FC1 to FC2, respectively. In the acid treatment, first, 59 parts by mass of an aqueous HCl solution (concentration: 1 mol/L) was added to 100 parts by mass of the waste FCC catalyst, and the mixture was stirred for 3 minutes using a Hobart mixer, and then allowed to stand in a sealed polyethylene bag for 1 day. The mixture was then removed from the bag and dried at 105°C for 1 day to evaporate the water. After drying, the mixture was pulverized for 15 minutes using a ball mill. The average particle sizes of the waste FCC catalysts FC1-B and FC2-B were 23 μm and 22 μm, respectively.

(C) Alkali Treatment Step The waste FCC catalysts FC1-C to FC3-C are alkali-treated products of the waste FCC catalysts FC1 to FC3, respectively. The alkali treatment was carried out by first adding 50 parts by mass of an aqueous NaOH solution (concentration: 1 mol/L) to 100 parts by mass of the waste FCC catalyst, stirring for 3 minutes in a Hobart mixer, and then allowing the mixture to stand in a sealed polyethylene bag for 1 day. The mixture was then removed from the bag and dried at 105°C for 1 day to evaporate the water. After drying, the mixture was pulverized for 15 minutes in a ball mill. The average particle sizes of the waste FCC catalysts FC1-C to FC3-C were 14 μm, 14 μm, and 28 μm, respectively.

(D) Heat Treatment Step The waste FCC catalysts FC1-D and FC3-D are heat-treated products of the waste FCC catalysts FC1 and FC3, respectively. The heat treatment was carried out by first pulverizing the waste FCC catalyst in a ball mill for 15 minutes. The pulverized waste FCC catalyst was heated in an electric furnace at 900°C for 1 hour. The average particle diameters of the waste FCC catalysts FC1-D and FC3-D were 25 μm and 31 μm, respectively.

The chemical composition of the various components in Table 2 was quantified using a scanning X-ray fluorescence analyzer with the fundamental parameter method. For the X-ray fluorescence analysis, a "ZSX-100e" (product name) manufactured by Rigaku Corporation was used.

The acid-insoluble residue (insol) of each component in Table 2 was measured in accordance with JIS R 5202:2015 "Methods for Chemical Analysis of Cement."

The Blaine specific surface area of each component in Table 2 was measured in accordance with JIS R 5201:2015, "Physical Measurement Methods for Cement." The density value used to measure the Blaine specific surface area of the spent FCC catalyst was measured using an automatic wet true density measuring device (manufactured by Seishin Enterprise Co., Ltd., product name: MAT-7000) using the liquid-phase displacement method (pycnometer method) in ethanol.

(Examples 1 to 8, Reference Example 1, and Comparative Examples 1 to 5)
Mixed cement compositions were prepared by mixing and pulverizing cement clinker, gypsum, limestone, and admixtures in the proportions (mass%) shown in Table 3. Specifically, cement clinker and gypsum were first mixed and pulverized in a ball mill to obtain a base cement. The Blaine specific surface area of the base cement was 3130 ^cm2 /g. The gypsum content in the base cement was 1.0 mass% in terms of _SO3 . Next, the admixtures were mixed in the types and proportions shown in Table 3 to prepare the cement compositions of the Examples, Reference Examples, and Comparative Examples. The cement composition of Reference Example 1 is an example based on common ordinary Portland cement, and Comparative Example 1 is an example based on a cement composition in which part of the cement clinker was replaced with fly ash.

<Measurement of compressive strength>
Using each of the cement compositions prepared in Examples 1 to 8, Reference Example 1, and Comparative Examples 1 to 5, compressive strength was measured in accordance with the description of JIS R 5201:2015 "Physical Testing Methods for Cement." The results are shown in Table 3. The compressive strengths shown in Table 3 are relative values, with the compressive strength of the cement composition of Reference Example 1 taken as 100.

Specifically, a mortar composition was prepared by mixing 100 parts by mass of the above cement composition with 300 parts by mass of standard sand for cement strength tests obtained from the Cement Association as fine aggregate and 50 parts by mass of water. The mortar composition was then kneaded and molded. The formwork was then placed in a humidity chamber with a relative humidity of 90% or higher and cured at 20°C for 24 hours. The formwork was then demolded to obtain a hardened mortar.

The prepared hardened mortar was then underwater cured in a thermostatic chamber at 20°C. On the seventh day after underwater curing, the hardened mortar was removed from the water and its compressive strength was measured. The relative value of the compressive strength to that of the reference mortar (Reference Example 1) was calculated ((compressive strength of test mortar at a specified age / compressive strength of reference mortar at a specified age) x 100).

As shown in Table 3, compared to the case where a cement composition consisting of cement clinker, gypsum, and limestone was used (Reference Example 1), the cement composition (Comparative Example 1) in which fly ash was further added and the cement clinker substitution ratio was increased was confirmed to result in a reduction in _CO2 emissions related to production, but also in a decrease in compressive strength.

Furthermore, it was confirmed that cement compositions (Comparative Examples 2 to 5) using waste FCC catalyst, which has little track record of use, as an admixture in place of fly ash were able to exhibit compressive strength equal to or greater than that of cement compositions using fly ash, but that the compressive strength did not exceed that of conventional ordinary Portland cement (Reference Example 1).

On the other hand, it was confirmed that cement compositions (Examples 1 to 9) using waste FCC catalysts with Blaine specific surface areas within the range specified in this application can exhibit excellent early strength that exceeds the compressive strength of conventional ordinary Portland cement (Reference Example 1).

Furthermore, it was confirmed that the cement compositions (Examples 5, 6, and 8) using a waste FCC catalyst with a lower insol content and _R2O content as an admixture can exhibit superior compressive strength compared to the cement compositions (Examples 7 and 9) using a waste FCC catalyst with a higher insol content as an admixture.

This disclosure provides a cement composition and a method for producing the same that can contribute to reducing environmental impact by using waste materials as admixtures and exhibit excellent early compressive strength.

Claims (5)

cement clinker, gypsum, and spent FCC catalyst;
The Blaine specific surface area of the spent FCC catalyst is 4000 cm ² /g or more ;
The cement composition , wherein the residue of the waste FCC catalyst insoluble in hydrochloric acid is 85% by mass or less, and the amount of R ₂ O is 0.70% by mass or less . 2. The cement composition according to claim 1 , wherein the spent FCC catalyst is any one of an acid-treated product, an alkali-treated product, and a heat-treated product. Further containing limestone,
The total amount of the spent FCC catalyst and the limestone is more than 5.0 mass% and 30.0 mass% or less,
3. The cement composition according to claim 1 , wherein the content of the spent FCC catalyst is 0.1 to 90 mass% based on the total amount of the spent FCC catalyst and the limestone. A step of adjusting the particle size of the spent FCC catalyst so that the Blaine specific surface area of the spent FCC catalyst is 4000 cm ² /g or more;
mixing the spent FCC catalyst with cement clinker and gypsum ;
The method for producing a cement composition , wherein the waste FCC catalyst has an insoluble residue in hydrochloric acid of 85% by mass or less and an R ₂ O content of 0.70% by mass or less . The method according to claim 4 , further comprising a step of subjecting the spent FCC catalyst to at least one treatment selected from the group consisting of an acid treatment, an alkali treatment, and a heat treatment.