Cement manufacturing method, cement manufacturing system, method for manufacturing cement hardened product

Abstract

To provide a cement manufacturing method capable of effectively utilizing a biomass ash, while suppressing an increase of a chlorine content rate of a generated cement hardened material, a cement manufacturing method and a cement manufacturing system.SOLUTION: A cement manufacturing method of the present invention comprises: a step (a) of classifying a biomass ash into coarse powder and fine powder; and a step of charging the coarse powder obtained in the step (a) to at least any one of a cement clinker raw material charged into a cement kiln, a cement clinker obtained from the cement kiln, or a cement after pulverization treatment to the cement clinker.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a cement manufacturing method and a cement manufacturing system, and particularly to a cement manufacturing method and a cement manufacturing system that utilize biomass ash as a cement raw material or the like. The present invention also relates to a method for manufacturing a cement hardened product using biomass ash.

Background Art

[0002] In recent years, incineration ash generated by incinerating municipal waste or the like is desired to be recycled as a cement raw material or the like against the background of the increasing pressure on disposal sites. In addition, due to various efforts towards the spread of renewable energy, the construction and operation of biomass power generation facilities have been progressing, and the amount of incineration ash (biomass ash) generated by biomass power generation is also increasing. For this reason, it is expected that biomass ash will be recycled as a cement raw material or the like, similar to incineration ash of municipal waste or the like.

[0003] In relation to such problems, for example, in Non-Patent Document 1 below, applying biomass ash as a cement admixture has been studied.

Prior Art Documents

Non-Patent Documents

[0004] Takahiro Sagawa et al., "Application of Wood Biomass Incineration Ash to Cement Admixtures", Proceedings of the 70th Cement Technology Conference, 2016

[1307]

Summary of the Invention

Problems to be Solved by the Invention

[0005] In Non-Patent Document 1 above, biomass ash is used as a cement admixture as it is. However, according to this method, since biomass ash contains a large amount of chlorine, the chlorine content of the concrete using the obtained cement may exceed the regulated value, and in some cases, there is a risk of causing rebar corrosion.

[0006] An object of the present invention is to provide a cement manufacturing method and a cement manufacturing system that can effectively utilize biomass ash while suppressing an increase in the chlorine content of the produced hardened cement product.

Means for Solving the Problems

[0007] The cement manufacturing method according to the present invention includes a step (a) of classifying biomass ash into coarse powder and fine powder, and a step (b) of introducing the coarse powder obtained in the step (a) into at least one of a cement clinker raw material to be charged into a cement kiln, a cement clinker obtained from the cement kiln, or cement after pulverization treatment for the cement clinker.

[0008] As described above, since biomass ash has a high chlorine content, if it is directly introduced into a cement clinker raw material, a cement clinker (hereinafter, both may be collectively referred to as "cement raw materials"), or cement, it may exceed the chlorine regulation value in concrete and cause rebar corrosion.

[0009] Among biomass ash, the relatively large-sized coarse powder has lower contents of calcium, sulfur, chlorine, and carbon and is closer to the composition of coal ash than the relatively small-sized fine powder. Therefore, when used as a clinker raw material, the homogeneity with respect to the conventional clinker raw material can be ensured. In particular, since the contents of sulfur and chlorine are low, there is an effect that coating in the cement kiln is less likely to be generated and an increase in the load on chlorine bypass is less likely to occur. Also, even when used as a cement admixture, since the contents of calcium, sulfur, chlorine, and carbon are low, there is an effect that the quality of the cement can be homogenized.

[0010] As specific methods of the above step (b), examples include input into raw material preparation system equipment such as mixers and grinders for preparing raw materials of cement clinker, input into the preheater top or calciner before the cement kiln (rotary kiln), input into the kiln end of the cement kiln, input into the front of the cement kiln, input into the clinker cooler for cooling the cement clinker obtained by firing, input into the grinding device (mill) for grinding the cement clinker, input into the mixer for producing blended cement, input into the concrete mixer, etc. That is, the coarse powder of the biomass ash obtained in step (a) can be input at various stages during cement production and can be suitably used as a cement clinker raw material or a cement admixture.

[0011] Hereinafter, in this specification, when "admixture" is described, it refers to a material that is input to cement clinker or cement regardless of the cement production stage.

[0012] Therefore, by utilizing the differences in characteristics such as the chemical composition of the classified biomass ash (i.e., coarse powder and fine powder) obtained through step (a), considering the influence on clinker characteristics and the clinker manufacturing process and the influence on cement characteristics, all or part of the coarse powder and fine powder can be input into the raw material or admixture of cement clinker. As a result, compared with the case of directly inputting the biomass ash raw powder, the composition and characteristics of the cement clinker and cement will be different.

[0013] Note that at least a part of the coarse powder obtained in step (a) may be input into the cement raw material or cement, and it is not necessarily required that all of the coarse powder be input into the cement raw material or cement. The remaining coarse powder can be used, for example, as fine aggregate.

[0014] This step (a) is preferably carried out on biomass ash (preferably dry ash) in a state where water is not added and the hydration reaction does not proceed. For example, when the biomass ash is wet ash and in a state of aggregation or formation of hydrates, even when classification is performed, there is a possibility that a large amount of chlorine is contained in the coarse powder side.

[0015] In this specification, "dry ash" refers to biomass ash recovered in a dried state, without water being added until classification treatment is carried out, and without aggregation or formation of hydrates. Also, the above dry ash includes cases where water is added before classification treatment, but the water is added in a large amount and dispersed, and no hydrates are formed due to long-term storage. Further, in this specification, "wet ash" refers to, for example, main ash that is incineration residue discharged from the bottom of an incinerator or fly ash recovered by a dust collector, etc., recovered in a state containing moisture by water cooling or sprinkling, or a dried product thereof. Generally, wet ash has a water content of 15% by mass or more.

[0016] The cement manufacturing method has a step (c) of introducing the fine powder obtained in the step (a) into at least one of the cement clinker or the cement after pulverization treatment of the cement clinker. The step (b) may be a step of introducing the coarse powder obtained in the step (a) into the cement clinker raw material to be charged into the cement kiln.

[0017] Further, the cement manufacturing method has a step (c) of introducing the fine powder obtained in the step (a) into the cement clinker raw material. The step (b) may be a step of introducing the coarse powder obtained in the step (a) into the cement clinker raw material to be charged into the cement kiln.

[0018] Although biomass ash has low activity, the finer the ash powder with smaller particle size, the higher the activity and the higher the alkali metal content. Therefore, as in the above method, when the fine powder obtained after classifying the biomass ash is mixed with the cement raw material or cement, the pozzolanic reaction is activated. Accordingly, the strength of the cement hardened product is increased as compared with the case where the biomass ash before classification (hereinafter sometimes referred to as "raw ash") is put into the cement raw material or cement.

[0019] In addition, when all of the fine powder and coarse powder obtained simply in step (a) are put into the cement clinker raw material without performing the water washing step (d) described later, it is the same as putting in the raw ash, so it is excluded from the present invention.

[0020] The cement manufacturing method includes a step (d) of washing the biomass ash. The step (c) may be a step of putting in the fine powder after being washed by the step (d).

[0021] According to the study by the present inventors, biomass ash contains components harmful in cement and concrete, and the quality stability is poor due to the presence of easily reactive calcium components. For this reason, there was a concern of being restricted in resource utilization as a cement raw material or the like. On the other hand, according to the above method, since the biomass ash passed through the water washing step (d) is put into the cement raw material (cement clinker raw material, cement clinker) or cement, the chlorine which is a cement-repellent component in the put-in biomass ash is efficiently removed, and the corrosion of the reinforcing bars of the concrete as the cement hardened product can be suppressed. In addition, heavy metals such as selenium and chromium which may cause environmental pollution, and easily reactive calcium oxide and calcium hydroxide are reduced, and the quality of the cement can be homogenized. When the biomass ash passed through the water washing step (d) is used as the clinker raw material, the blockage due to the adhesion of low melting point substances to the preheater, the kiln end, and the kiln is suppressed.

[0022] This water washing step (d) preferably includes a step (d1) of adding water to the biomass ash to form a slurry, a step (d2) of supplying washing water to the slurry for water washing, and a step (d3) of dehydrating the slurry after water washing. By forming a slurry, performing water washing, and then dehydrating, chlorine and heavy metals can be removed to obtain a dehydrated product.

[0023] Note that the step (b) may be a step of introducing the coarse powder obtained by classifying the biomass ash after the water washing treatment in the step (d) into cement raw materials or cement.

[0024] The step (d) may be configured to wash only the fine powder obtained in the step (a).

[0025] According to the study by the present inventors, when comparing the coarse powder and the fine powder obtained after classifying the biomass ash, it was confirmed that most of the chlorine content in the biomass ash is contained in the fine powder. Therefore, according to the above method, chlorine contained in the biomass ash can be efficiently removed while suppressing the amount of water used for water washing.

[0026] The cement manufacturing method includes a step (e) of pulverizing at least a part of the coarse powder obtained in the step (a). The step (b) may be a step of introducing the coarse powder pulverized in the step (e) into cement clinker obtained from the cement kiln or cement after pulverization treatment of the cement clinker.

[0027] According to this method, since the coarse powder is pulverized and has a finer particle size and is introduced into cement clinker or cement, the strength of the cement can be increased. Note that the pulverization of the coarse powder may be performed simultaneously with the pulverization of the cement clinker.

[0028] The cement manufacturing method may include a step (f) of oxidizing the biomass ash during or after the execution of the step (d).

[0029] According to the above method, since the pH during water washing is adjusted to the acidic side, chlorine can be removed more efficiently. Also, even when a large amount of reactive calcium oxide or calcium hydroxide is contained in the biomass ash, it can be completely replaced with calcium carbonate or calcium sulfate, so the quality such as the fluidity of the cement can be homogenized.

[0030] As step (f), an acid solution may be added during the water washing of the biomass ash, or a gas containing carbon dioxide (CO2) may be blown in, or a gas containing CO2 may be blown in against the biomass ash after the water washing treatment. In particular, by using the combustion exhaust gas of a cement kiln, the extraction gas of a chlorine bypass, or the combustion exhaust gas of a biomass incineration facility or a biomass power plant as the gas containing CO2, the CO2 contained in these gases can be changed to calcium carbonate and fixed to the biomass ash, so an effect of reducing the CO2 emission amount can also be expected. In addition, harmful gases such as sulfur oxides (SO x ) contained in the exhaust gas can also be changed to calcium sulfate and immobilized to the biomass ash.

[0031] Also, particularly in step (f), by carbonating the biomass ash during the water washing according to step (d), the calcium content contained in a large amount in the waste liquid after water washing can be precipitated as calcium carbonate, so the generation of scale is suppressed. Thereby, it is possible to suppress the blockage of pipes and the like for wastewater treatment.

[0032] The cement manufacturing method may also have a step (g) of removing unburned carbon contained in the biomass ash during the execution of step (d).

[0033] Biomass ash (raw ash) may contain a lot of unburned carbon. Therefore, when using biomass ash rich in carbon as a cement clinker raw material, it may cause the preheater temperature to rise. When used as a blending material, it may cause the concrete to turn black or the fluidity to decrease due to the adsorption of the water reducer by carbon.

[0034] On the other hand, according to the above method, since unburned carbon can be removed during washing, the occurrence of the above-mentioned problems can be suppressed. Specifically, it is possible to reduce the amount of unburned carbon contained by performing flotation by mixing a carbon removal agent such as oil or surfactant.

[0035] The step (c) may also be a step of mixing at least one of latent hydraulic substances and pozzolan in addition to the fine powder.

[0036] When the fine powder after classification of biomass ash is input during cement production, cement with a high alkali metal content can be produced. When this cement is mixed with aggregates to produce concrete, the alkali-reactive minerals (such as amorphous silica) in the aggregates react with alkali metals to generate water-absorbing alkali-silica gel, which may cause cracks in the concrete (alkali-aggregate reaction).

[0037] On the other hand, according to the above method, since latent hydraulic substances such as blast furnace slag and pozzolan (including natural pozzolan such as silica powder and stone powder, and artificial pozzolan such as fly ash and calcined clay) are input together with the fine powder, the alkali-aggregate reaction can be suppressed.

[0038] However, by using aggregates that are less likely to cause alkali-aggregate reaction as the aggregates mixed during concrete production, it is possible to suppress the alkali-aggregate reaction without mixing latent hydraulic substances or pozzolan.

[0039] It is preferable that the step (a) is a step of classifying with a classification point of 20 μm or more and 100 μm or less. As a result, especially chlorine and sulfur are dominantly distributed to the fine powder side, which is efficient.

[0040] The cement manufacturing system according to the present invention classification equipment for classifying biomass ash into coarse powder and fine powder, a cement kiln for firing a cement clinker raw material to produce a cement clinker, and first pulverization equipment for pulverizing the cement clinker obtained from the cement kiln to produce cement, characterized in that the coarse powder obtained by the classification device is introduced into at least one of the cement clinker raw material, the cement clinker obtained from the cement kiln, or the cement obtained from the first pulverization equipment.

[0041] According to the above system, since the coarse powder obtained after classifying the biomass ash is introduced into the cement raw material or the cement, the chlorine content is reduced compared to the case where the raw ash is mixed with the cement raw material or the cement, and the induction of rebar corrosion can be suppressed.

[0042] At this time, the coarse powder obtained by the classification device may be introduced into the first pulverization equipment.

[0043] According to this, a step of pulverizing the coarse powder can be performed in parallel with the step of pulverizing the cement clinker. Thereby, the strength of the cement can be increased without providing separate pulverization equipment.

[0044] Further, the cement manufacturing system includes second pulverization equipment for pulverizing the coarse powder classified by the classification equipment, and the coarse powder after being pulverized by the second pulverization equipment may be introduced into at least one of the cement clinker obtained from the cement kiln or the cement obtained from the first pulverization equipment.

[0045] In addition, the method for manufacturing a cement hardened product according to the present invention comprises: a step (a) of classifying biomass ash into coarse powder and fine powder; a step (e) of pulverizing the coarse powder obtained in the step (a); and a step (b) of charging the pulverized coarse powder obtained in the step (e), cement after the pulverization treatment, and water, and is characterized by this.

[0046] Also by this method, for the same reason as described above, a cement hardened product having a lower chlorine content and higher strength can be obtained compared to the case where raw ash before classification is charged. Examples of the cement hardened product include concrete and mortar. In any case, appropriate aggregates may be appropriately charged in addition to the pulverized coarse powder, cement, and water. After charging these, they may be mixed as a concrete admixture in a concrete mixer, for example.

Advantages of the Invention

[0047] According to the present invention, it becomes possible to effectively utilize biomass ash in cement production while suppressing an increase in the chlorine content of the generated cement hardened product.

Brief Description of the Drawings

[0048]

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Mode for Carrying Out the Invention

[0049] [Biomass Ash] The present invention relates to a technique of using biomass ash in cement manufacturing. First, the biomass ash to which the present invention is applied will be described.

[0050] The biomass ash to which the present invention is applied widely includes generally incineration ash of biomass, for example, incineration ash of plants, bamboo, and food residues. Biomass ash contains water-soluble alkali metal chlorides, alkali metal sulfates, and alkali metal carbonates. Biomass ash has the advantage that the proportion of alkali metal sulfates and alkali metal carbonates is larger and the alkali chloride concentration is lower than that of municipal solid waste incineration ash and chlorine bypass dust.

[0051] Since biomass ash is incineration ash, it contains glass components with pozzolanic reactivity similar to coal ash. Among biomass ashes, the incineration ashes of plants, trees, and bamboo have a relatively high K2O content, and in some cases, potassium (K2O) is embedded in the glass phase and contained therein. Therefore, since biomass ash has high activity when used as a blending material, it is preferably used during cement production.

[0052] The K2O content of biomass ash is preferably 2% to 10% by mass, more preferably 3% to 8% by mass, and even more preferably 3% to 5% by mass. If the K2O content of biomass ash is less than 2% by mass, the strength of the cement when used as a blending material may decrease, and there is also a possibility that the required amount as a material to be added to the cement cannot be ensured. On the other hand, if the K2O content of biomass ash exceeds 10% by mass, the amount used when used as a raw material for cement clinker may be limited, or the occurrence of alkali-aggregate reaction may increase when used as a blending material.

[0053] The total alkali concentration contained in biomass ash is preferably 2% to 11% by mass in terms of R2O conversion (R2O = Na2O + 0.658×K2O), and more preferably 3% to 6% by mass. Also, the concentration of sulfur oxides (SO3) contained in biomass ash is preferably 0.5% to 6% by mass, and more preferably 1% to 5% by mass.

[0054] In biomass power plants, co-firing of biomass and coal may be carried out, but the biomass ash to which the present invention is applied also includes ash generated when such co-firing is performed. However, generally, coal ash obtained by burning coal has a low K2O content, so the activity of biomass ash varies depending on the amount of coal used during co-firing. Therefore, from the perspective of resource utilization as a blending material during cement production, in the case of co-firing with coal, it is preferably ash obtained from those with a biomass ratio of 50% by mass or more in the fuel.

[0055] As the biomass ash to which the present invention is applied, palm coconut shell ash (PKS ash) obtained by using palm coconut shell as fuel among the incineration ashes of grass, trees and bamboo is preferably exemplified. Palm coconut shell is a by-product of palm oil production and is mainly used in the natural biomass energy industry. Palm coconut shell is a yellowish-brown fibrous substance with little ash content, its particle size is about 5 mm to 40 mm, and its calorific value is about 4000 Kcal / kg. Therefore, in energy production using renewable resources, the use of palm coconut shell as fuel for biomass power generation has been increasing in recent years.

[0056] Generally, combustion furnaces for biomass power generation include stoker type and fluidized bed type. In fluidized bed type combustion furnaces such as circulating fluidized bed type and pressurized fluidized bed type, limestone is introduced to perform desulfurization in the furnace. Therefore, the biomass ash from such combustion furnaces contains a large amount of calcium component and sulfur component. For example, the CaO content rate is generally 5% by mass to 45% by mass. In addition, as the form of Ca compounds derived from the introduced limestone, forms such as CaO (quicklime), Ca(OH)2 (slaked lime), CaCO3 (limestone), CaSO4 (gypsum), etc. are included.

[0057] The CaO content rate of the biomass ash to which the present invention is applied is preferably 10% by mass to 40% by mass, and more preferably 15% by mass to 30% by mass, from the viewpoint of the strength of cement when it is recycled as a admixture.

[0058] As the ash type of the biomass ash to which the present invention is applied, it may be the main ash remaining unburned at the furnace bottom in a combustion furnace for biomass power generation or the like, or it may be fly ash obtained by collecting the dust floating as a gas contained in the combustion exhaust gas by a dust collector. Among these, fly ash is preferable because it has a higher alkali metal and chlorine concentration and chlorine is more easily separated by classification or water washing, which is efficient.

[0059] Also, the biomass ash is preferably dry ash. Biomass ash that has been once sprayed with water may become granular, or chlorine may be incorporated into the generated hydrate, making it difficult to separate chlorine by classification or water washing. As the dry ash, for example, it is preferable that Friedel's salt or ettringite, which is a hydrate, is not detected by powder X-ray diffraction method. Or, the water content is preferably 10% by mass or less, more preferably 5% by mass or less. Or, the loss on ignition is preferably 10% or less. The water content can be determined as the mass reduction rate when dried at 105°C. Also, the loss on ignition can be determined as the mass reduction rate when the object dried at 105°C is heated at 975°C.

[0060] Also, the structural water amount of the hydrate in the biomass ash may be determined as the hydrate generation amount by subtracting the decarbonation amount due to calcium carbonate from the loss on ignition. The hydrate generation amount is preferably 5% or less, more preferably 3% or less.

[0061] The particle size of the biomass ash is, for example, such that the strength of the cement is higher, and the median diameter (D 50 ) is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 90 μm or less. The particle size can be measured using a laser diffraction / scattering type particle size distribution measuring device. For example, it can be measured using MW3300EXII manufactured by Microtrac Bell Co., Ltd. with ethanol as the dispersion medium and measuring after 1 minute of ultrasonic dispersion. Note that the D 50 value means the particle size at 50% cumulative in the volume-based particle size distribution.

[0062] [First Embodiment] The first embodiment of the cement manufacturing method and the cement manufacturing system will be described. FIG. 1 is a drawing schematically showing the processing flow of the cement manufacturing method in this embodiment. FIG. 2 is a block diagram schematically showing the structure of the cement manufacturing system in this embodiment.

[0063] The cement manufacturing system 1 shown in FIG. 2 includes a raw material tank 3 in which a cement clinker raw material Y1 is stored, a powder storage tank 5 in which biomass ash B1 is stored, a clinker manufacturing facility 10, a classification facility 20, and a first pulverization facility 30. The clinker manufacturing facility 10 is a facility that fires the cement clinker raw material Y1 to generate cement clinker Cn1, and includes a cement kiln 12 for firing, a preheater 11 for preheating the cement clinker raw material Y1 before being charged into the cement kiln 12, and a clinker cooler 13 for cooling the cement clinker Cn1 after firing.

[0064] As shown in FIG. 1, the cement manufacturing method of the present embodiment includes a step S10 of classifying the biomass ash B1 and a step S20 of charging or adding the classified biomass ash B1 to cement raw materials or the like. Hereinafter, the charging or adding step is collectively referred to as the "charging" step.

[0065] (Classification step S10) The biomass ash B1 stored in the powder storage tank 5 is classified by the classification facility 20 into a coarse powder B1C having a coarse particle size and a fine powder B1F having a fine particle size based on a predetermined classification point. The classification point determined in the classification step S10 is preferably 20 μm or more and 100 μm or less, more preferably 30 μm or more and 90 μm or less, and particularly preferably 38 μm or more and 75 μm or less.

[0066] The classification facility 20 is not particularly limited as long as it can classify the biomass ash B1 at a classification point on the μm order as described above. For example, a sieve, gravity sedimentation, inertial classification device, centrifugal classification device, gravity type classification device, etc. can be preferably used. From the viewpoint of classification accuracy in particular, the use of a cyclone type air separator, a vortex type centrifugal classification device, a sieving device, etc. is preferable. When performing water washing, it is efficient to perform it wet.

[0067] In a fluidized bed incinerator, sand mainly composed of quartz as a fluid medium and limestone for desulfurization are introduced. Therefore, the fly ash of biomass ash from such an incinerator contains relatively coarse molten solidified or aggregated glass and sand-derived substances, and relatively fine volatile alkali metal salts and the aforementioned limestone-derived substances. Therefore, when the particle size distribution of biomass ash is represented by frequency, if the classification point is set between the peak on the fine particle side and the peak on the coarse particle side, chlorine, sulfur, and calcium can be efficiently separated.

[0068] Figure 3 is a graph showing the particle size distribution of incineration fly ash from the biomass power generation facility P1 of Example 1 described later. According to the graph of Figure 3, it is confirmed that peaks appear on the fine particle side and the coarse particle side, respectively. It is considered that the fine particle side is derived from lime and alkali metal salts, and the coarse particle side is derived from quartz and glass. Therefore, it can be seen that by classifying using the particle size in the region (valley region) between these peaks as the classification point, chlorine, sulfur, and calcium can be efficiently separated. A fluidized bed incinerator may be equipped with equipment for recovering incineration ash deposited in a boiler, an air preheater, a high-temperature gas flow path, etc., incineration ash recovery equipment using a cyclone, and incineration ash recovery equipment using a bag filter. Since the particle sizes of the incineration ash recovered by these recovery facilities are different, they can be separately recovered and used instead of a classification device.

[0069] The classification equipment 20 may be attached with a storage tank for biomass ash B1. Furthermore, a supply device for quantitatively supplying biomass ash B1 from such a storage tank to the classification equipment 20 may be attached. These storage tanks and supply devices may be appropriately used according to the state of the received biomass ash B1.

[0070] Examples of the classification criteria in the classification step S10 include the activity index of the fine powder B1F, the yield of the fine powder B1F, the chlorine concentration, sulfur oxide concentration, and calcium oxide concentration of the fine powder B1F and the coarse powder B1C.

[0071] The activity index of the fine powder B1F obtained in the classification step S10 is higher than that of the biomass ash (raw ash) B1, typically 70% or more in 7 days and 65% or more in 28 days, and more typically 75% or more in 7 days and 70% or more in 28 days.

[0072] The activity index contained in the biomass ash B1 (B1C, B1F, etc.) can be measured by a well-known method. For example, a method conforming to JISA 6201:2015 "Fly Ash for Concrete" is preferably exemplified.

[0073] The yield of the fine powder B1F is preferably 10% by mass to 80% by mass, more preferably 20% by mass to 70% by mass, and still more preferably 30% by mass to 60% by mass. The yield of the fine powder B1F may be defined as the ratio of the total mass of the obtained fine powder B1F to the total mass of the biomass ash B1 before the execution of the classification step S10. On the other hand, the yield of the coarse powder B1C is preferably 20% by mass to 90% by mass, more preferably 30% by mass to 80% by mass, and still more preferably 40% by mass to 70% by mass.

[0074] The chlorine concentration ratio of the fine powder B1F to the coarse powder B1C is preferably 4 or more, more preferably 8 or more, and still more preferably 12 or more. The chlorine concentration of the fine powder B1F typically becomes, for example, 0.2% by mass to 2% by mass, and more typically 0.3% by mass to 1.5% by mass. On the other hand, the chlorine concentration of the coarse powder B1C is typically reduced to 0.01% by mass to 0.2% by mass, and more typically reduced to 0.02% by mass to 0.1% by mass.

[0075] The chlorine concentration contained in the biomass ash B1 (B1C, B1F, etc.) can be measured by a well-known method. For example, a method of measuring by potentiometric titration after acid decomposition treatment is preferably exemplified.

[0076] The total alkali concentration ratio of the fine powder B1F to the coarse powder B1C is preferably 1.05 or more, more preferably 1.1 or more, and still more preferably 1.2 or more in terms of R2O conversion (R2O = Na2O + 0.658 × K2O). The total alkali concentration of the fine powder B1F typically becomes, for example, 2% by mass to 10% by mass, and more typically 3% by mass to 8% by mass. On the other hand, the total alkali concentration of the coarse powder B1C is typically reduced to 0.5% by mass to 6% by mass, and more typically reduced to 2% by mass to 5% by mass.

[0077] The total alkali concentration contained in the biomass ash B1 (such as B1C, B1F, etc.) can be measured by a well-known method. For example, a method conforming to JIS R 5204 "Fluorescent X-ray Analysis Method for Cement" is preferably exemplified.

[0078] The sulfur oxide concentration ratio of the fine powder B1F to the coarse powder B1C is preferably 5 or more, more preferably 10 or more, and still more preferably 20 or more. The sulfur oxide concentration of the fine powder B1F typically becomes, for example, 1% by mass to 6% by mass, and more typically 2% by mass to 5% by mass. On the other hand, the sulfur oxide concentration of the coarse powder B1C is typically reduced to 0.01% by mass to 2% by mass, and more typically reduced to 0.05% by mass to 1% by mass.

[0079] The sulfur oxide concentration contained in the biomass ash B1 (such as B1C, B1F, etc.) can be measured by a well-known method. For example, a calibration curve method using a fluorescent X-ray apparatus is preferably exemplified.

[0080] The calcium oxide concentration ratio of the fine powder B1F to the coarse powder B1C is preferably 1.5 or more, more preferably 2 or more, and still more preferably 3 or more. The calcium oxide concentration of the fine powder B1F typically becomes, for example, 8% by mass to 40% by mass, and more typically 15% by mass to 35% by mass. On the other hand, the calcium oxide concentration of the coarse powder B1C is typically reduced to 3% by mass to 15% by mass, and more typically reduced to 5% by mass to 10% by mass.

[0081] The calcium oxide concentration contained in biomass ash B1 (B1C, B1F, etc.) can be measured by a well-known method. For example, the calibration curve method using a fluorescent X-ray device is preferably exemplified.

[0082] This classification step S10 corresponds to step (a).

[0083] (Input step S20) The coarse powder B1C obtained in the classification step S10 is put (added) as a raw material for cement clinker or as a mixing material to cement clinker or cement. In the example of FIG. 2, the case where the coarse powder B1C is put into the clinker production facility 10 and the case where it is put into the first grinding facility 30 that mixes and grinds the cement clinker Cn1 obtained from the clinker production facility 10 with gypsum as necessary are illustrated. In the latter case, by performing a grinding process on the coarse powder B1C together with the cement clinker Cn1, a blended cement is produced. At that time, watering or a grinding aid is added as necessary. However, the coarse powder B1C may be put into either one of the clinker production facility 10 and the first grinding facility 30.

[0084] As the first grinding facility 30, a general mill used in a finishing process such as a tube mill can be used. The mill is also called a finishing grinder, and in a cylindrical drum, steel balls, cement clinker Cn1, and gypsum added as necessary collide with each other by the rotation of the drum and are ground. When using gypsum, the gypsum is not particularly limited, and examples include natural dihydrate gypsum, flue gas desulfurization gypsum, phosphogypsum, titanium gypsum, fluoro gypsum, etc. These may be used alone or in combination of two or more.

[0085] The coarse powder B1C replaces a part of the cement raw material, and it is preferably added in an amount of 0.5% by mass to 30% by mass based on the mass of the cement raw material. Also, it is preferable to add gypsum in an amount of preferably 1.5% by mass to 5.0% by mass in terms of SO3 in order to improve the strength development and fluidity of the cement.

[0086] Alternatively, the crude powder B1C obtained in the classification step S10 may be directly charged into the clinker cooler 13. As a charging method, a method of dropping from the upper part of the clinker cooler 13 to a position at a desired temperature inside the clinker cooler 13 can be mentioned. The charging amount is preferably set to be about 0.5% by mass to 20% by mass with respect to the mass of the cement. In addition, if an air quenching cooler is used as the clinker cooler 13, it is preferable because the crude powder B1C can be charged to a predetermined position inside the clinker cooler 13.

[0087] When the crude powder B1C is washed with water and then charged into the clinker cooler 13, it is convenient because the moisture can be evaporated and removed by using thermal energy that has no direct relation to the production of the cement clinker Cn1. Further, from the meaning of preventing a large amount of dust from being generated inside the clinker cooler 13, the crude powder B1C preferably has a water content of 50% by mass or less, and is preferably charged in a lump or granular form.

[0088] The crude powder B1C obtained after the classification step S10 is also reduced in terms of the alkali metal concentration, calcium concentration, chlorine concentration, and sulfur concentration compared to the fine powder B1F. Therefore, as shown in FIG. 2, it can be used in the clinker production facility 10 together with the cement clinker raw material Y1. For example, it can be charged into a mixer for preparing the cement clinker raw material Y1 in the clinker production facility 10, charged into the preheater 11 or the calciner, charged into the kiln end or the kiln front of the cement kiln 12, etc., and can be suitably used as a raw material for the cement clinker Cn1 that can be charged at various cement production stages.

[0089] As another example, as shown in FIG. 4, the cement production system 1 may be provided with a grinding facility (second grinding facility 35) different from the first grinding facility 30 for grinding the cement clinker Cn1. The crude powder B1C classified in the classification facility 20 may be ground in the second grinding facility 35 and then charged into the clinker cooler 13 or the first grinding facility 30. The second grinding facility 35 can be realized by the same facility as the first grinding facility 30.

[0090] Furthermore, the coarsely ground powder B1C after pulverization may be mixed with respect to the cement obtained after the cement clinker Cn1 is pulverized in the first pulverization facility 30. The timing of this mixing may be on the path up to the cement silo where the cement is stored after the first pulverization facility 30, may be inside the cement silo, or may even be during the concrete mixing process when using the cement. Since the coarsely ground powder B1C has a low chlorine content, regardless of the timing of mixing the coarsely ground powder B1C, an effect of suppressing an increase in the chlorine content of the cement hardened product can be obtained while using the biomass ash B1.

[0091] The coarsely ground powder B1C is preferably pulverized so that the Blaine specific surface area is 4000 cm 2 / g or more, and particularly preferably pulverized so that it is 4500 cm 2 / g or more. Also, the activity index of the coarsely ground powder B1C after pulverization becomes higher than that of the biomass ash (raw ash) B1, typically 65% or more at 7 days and 70% or more at 28 days, and more typically 68% or more at 7 days and 70% or more at 28 days.

[0092] Also, as described above, in the classification step S10, the chlorine concentration of the coarsely ground powder B1C is greatly reduced, and furthermore, the sulfur content is also greatly reduced. Therefore, clogging due to adhesion of low-melting substances to the preheater, the kiln tail, and the kiln is suppressed. Also, the coarsely ground powder B1C in a state where its reactivity is enhanced by being pulverized in the second pulverization facility 35 may be used as a cement admixture.

[0093] This charging step S20 corresponds to step (b).

[0094] In the cement manufacturing system 1 of this embodiment, the utilization of the fine powder B1F classified in the classification facility 20 is not restricted. For example, as will be described later, similar to the coarse powder B1C, it may be used as a raw material for cement clinker or added (mixed) as a mixing material to cement clinker or cement, or it may be used as fertilizer or fine aggregate. In particular, since the fine powder B1F has a finer particle size and higher reactivity compared to the coarse powder B1C, by recovering this fine powder B1F and using it as a cement admixture, the pozzolanic reaction is activated and the strength of the cement hardened body is expected to be increased.

[0095] [Second Embodiment] The second embodiment of the cement manufacturing method and the cement manufacturing system will be described centering on the differences from the first embodiment. FIG. 5 is a drawing schematically showing the processing flow of the cement manufacturing method in this embodiment. FIG. 6 is a drawing schematically showing an example of the detailed processing flow of the water washing step S30 described later. FIG. 7 is a block diagram schematically showing the structure of the cement manufacturing system in this embodiment.

[0096] The cement manufacturing system 1 of this embodiment shown in FIG. 7 is different from that of the first embodiment in that it is provided with a water washing facility 40. The water washing facility 40 is a facility for washing the biomass ash B1 and is provided for the purpose of reducing the concentration of cement-repellent components such as chlorine contained in the biomass ash B1. An example of the detailed structure of the water washing facility 40 will be described later with reference to FIG. 8.

[0097] In the cement manufacturing system 1 of the present embodiment shown in FIG. 7, after the biomass ash (modified biomass ash B2) is washed with water and classified in the classification facility 20, the obtained coarse powder B2C is input into the cement manufacturing facility 10, and an example is illustrated in which the fine powder B2F is input into the first grinding facility 30 together with the cement clinker Cn1. However, similar to what was described above in the first embodiment, the coarse powder B2C may be input into the first grinding facility 30, or may be input into the cement obtained after the cement clinker Cn1 is ground in the first grinding facility 30. In particular, in the latter case, similar to what was described above with reference to FIG. 4, it is preferable that the coarse powder B2C is ground in the second grinding facility 35 and then mixed into the cement in a state where its reactivity is enhanced.

[0098] (Washing step S30) The biomass ash B1 is washed with water by the water washing facility 40. More specifically, as shown in FIG. 6, a step S31 of slurrying the biomass ash B1, a step S32 of washing the slurry with water, and a step S33 of dehydrating are executed.

[0099] As an example, the water washing facility 40 shown in FIG. 8 includes a powder dissolution tank 43 for adding water W1 to the accommodated biomass ash B1 to make it into a slurry Lr1 for washing with water, a solid-liquid separation device 46 for dehydrating the slurry Lr2 discharged from the powder dissolution tank 43 after washing with water, and a conveying device 47 for conveying the dehydrated product Ck1 separated by the solid-liquid separation device 46.

[0100] Furthermore, in the example of the water washing facility 40 shown in FIG. 8, the powder dissolution tank 43 is attached with a powder supply device 41 for supplying the biomass ash B1 and a liquid supply device 42 for supplying water W1. Also, for mixing the biomass ash B1 and water W1 and stirring the slurry Lr1 generated by the mixing, a slurry stirring device 44 equipped with stirring blades is attached.

[0101] In the powder dissolution tank 43, a slurrying step S31 of mixing and stirring the biomass ash B1 and water W1 to generate a slurry Lr1, and a water washing step S32 of eluting cement-repellent components such as chlorine into the liquid phase in the slurry Lr1 are performed. As a slurry stirring device 44 for this purpose, for example, a general stirring device such as a paddle type or a screw type can be used.

[0102] In the slurrying step S31, the mass ratio (W1 / B1) of the biomass ash B1 to the water W1 is preferably 2 to 10, more preferably 3 to 7, and particularly preferably 4 to 5. When the mass ratio (W1 / B1) is less than 2, the reforming effect may be insufficient, such as insufficient elution of water-soluble components such as chlorine from the biomass ash B1. Also, when the mass ratio (W1 / B1) is greater than 10, the amount of the drainage W3 increases.

[0103] The water washing step S32 is performed by allowing the slurry Lr1 to stand or stir for a predetermined time. Thereby, a slurry Lr2 in a state where the soluble components of the biomass ash B1 are eluted into the liquid phase of the slurry is obtained.

[0104] The required time for the water washing step S32 is preferably 30 minutes or more, more preferably 45 minutes or more, in order to sufficiently reform the biomass ash B1 with the water W1. Also, as for the temperature condition, the higher the temperature, the better the elution efficiency of water-soluble components such as chlorine from the biomass ash B1, but from the viewpoint of the cost related to the treatment, it is preferably 5°C to 50°C, more preferably 25°C to 50°C.

[0105] After the water washing step S32, the slurry Lr2 in a state where cement-repellent components such as chlorine are eluted into the liquid phase in the slurry is discharged from the powder dissolution tank 43 and transferred to the solid-liquid separation device 46. For the transfer of the slurry Lr2, a normal slurry liquid transport device (not shown) such as a slurry volute pump, a piston pump, or a mono pump may be used.

[0106] In the solid-liquid separation device 46, the slurry Lr2 is subjected to solid-liquid separation to obtain a dehydrated product Ck1 (dehydration step S33). As the solid-liquid separation device 46, ordinary filtration devices such as a filter press, a pressure leaf filter, a screw press, a belt press, a belt filter, sedimentation separation, etc. can be used.

[0107] In the dehydration step S33, in order to prevent water-soluble components such as chlorine contained in the slurry Lr2 from remaining together with the liquid phase, the water content of the dehydrated product is preferably 20% by mass to 90% by mass, and more preferably 30% by mass to 70% by mass.

[0108] Since the components eluted into the liquid phase of the slurry Lr2 are removed to the drainage W3, the obtained dehydrated product Ck1 has a reduced amount of cement-repellent components such as chlorine compared to the raw ash (biomass ash B1). On the other hand, since heavy metals and the like originally contained in the raw ash are also eluted in the drainage W3, it may be discharged into the environment after appropriately performing water purification treatment.

[0109] As shown in FIG. 8, a water washing device 49 may be attached to the solid-liquid separation device 46, and after adding water W2 to the dehydrated product Ck1, dehydration may be performed again. According to this, since the liquid phase of the slurry Lr2 is almost replaced with water, the eluted components can be more reliably removed.

[0110] This water washing step S30 corresponds to step (d).

[0111] The dehydrated product Ck1 obtained through the water washing step S30 is in a state where the biomass ash B1 is reformed (reformed biomass ash B2), the cement-repellent components such as chlorine are reduced, and the contents of easily reactive calcium oxide and calcium hydroxide that affect the strength development and fluidity of cement are sufficiently reduced. Therefore, by using this reformed biomass ash B2 and performing the classification and mixing steps in the same manner as in the first embodiment, it becomes easy to maintain the quality as a cement admixture uniformly. In particular, by using the biomass ash B1 discharged from a fluidized bed combustion furnace into which limestone containing a calcium component is introduced, the above effects can be significantly realized.

[0112] Note that the drainage water W3 obtained in the dehydration step S33 may be mixed with the cement clinker Cn1 in a state where the contained chloride ions are reduced by well-known methods such as ion exchange resin, membrane separation, and precipitation formation by silver or lead ions. Thereby, while removing chlorine that causes rebar corrosion, the alkali metals showing an effect of enhancing strength contained in the drainage water W3 can be effectively utilized. As in this embodiment, since the modified biomass ash B2 obtained by performing the water washing step S30 has low activity due to water washing, the weakness of the decrease in the activity of the modified biomass ash B2 can be compensated by adding the drainage water W3 after water washing as a cement additive.

[0113] In particular, since the biomass ash B1 has a lower chlorine concentration than municipal waste incineration ash, it is easy to separate the chlorine contained in the drainage water W3, and a large amount of alkali metal sulfates and carbonates can be obtained in the drainage water W3. Therefore, by introducing the drainage water W3 on the path from the clinker cooler 13 to the first grinding facility 30, more alkali metals can be utilized as a cement additive.

[0114] By introducing the drainage water W3 between the clinker cooler 13 and the first grinding facility 30, it can be used as a cement additive while serving as sprinkling water for cooling the cement clinker Cn1 and adjusting the temperature in the grinding facility 30 without drying or solidifying. More specific injection locations include the clinker cooler 13 at 400 °C or lower, the subsequent conveyor, and the first grinding facility 30 in the cement manufacturing facility. If the temperature exceeds 400 °C, it will evaporate instantaneously and will not be easily contained in the cement. If it is downstream of the first grinding facility 30, there is a risk that moisture will remain in the cement and the quality will deteriorate due to weathering and hydration.

[0115] Note that the drainage water W3 may be introduced between the clinker cooler 13 and the first grinding facility 30 in a state where moisture has been reduced by drying or the like. According to this, more alkali metals can be utilized as a cement additive without weathering the cement. In particular, if the drainage water W3 is dried and solidified, it can also be introduced during grinding of cement or concrete kneading, and any amount can be easily added.

[0116] As a means for reducing chlorine ions, those using an amphoteric ion exchange resin or a nanofiltration membrane are particularly preferable. According to this, sulfate ions, carbonate ions, and chlorine ions can be selectively separated, and water with a high sulfate ion and carbonate ion concentration and a low chlorine ion concentration, and water with a low sulfate ion and carbonate ion concentration and a high chlorine ion concentration can be obtained.

[0117] The wastewater W3 obtained after washing the biomass ash B1 often contains selenium and hexavalent chromium. By using the above-mentioned amphoteric ion exchange resin or nanofiltration membrane, selenium and hexavalent chromium, which exhibit the same form as sulfate ions, are separated to the side of water with a low chlorine concentration. The water with a high chlorine concentration is disposed of, but this water also has a low selenium and hexavalent chromium concentration, facilitating wastewater treatment. In addition, the amount of water can be reduced (the concentration of alkali metals can be increased) without drying, and when it is introduced between the clinker cooler 13 and the first grinding facility 30, more alkali metals can be utilized as a cement additive with the same amount of water sprayed.

[0118] As described above, since the wastewater W3 (cement additive) obtained from the washing water and the washed modified biomass ash B2 can be used as a cement admixture at the same time, the biomass ash B1 can be utilized without remainder. Thereby, an effect of reducing the amount of wastewater to be disposed of and the wastewater treatment load thereof can also be expected.

[0119] In addition, in the present embodiment, it is also possible to execute an oxidation step S41 and an unburned carbon removal step S42 together with the washing step S30 (see FIGS. 9A and 9B). These steps may be performed in parallel with the execution of the washing step S30, or may be performed after the execution of the washing step S30. Note that only one of the oxidation step S41 and the unburned carbon removal step S42 may be performed.

[0120] FIG. 9A is a drawing schematically showing a processing flow when both the oxidation step S41 and the unburned carbon removal step S42 are executed in the present embodiment, and FIG. 9B is a drawing schematically showing the structure of the water washing facility 40 in this case according to FIG. 8. In FIG. 9B, the gas supply device 51 and the flotation device 53 are also shown together with the water washing facility 40.

[0121] (Oxidation step S41) The oxidation step S41 is a step of oxidizing the biomass ash B1. As an example, in the water washing step S30, it can be executed by adding a pH adjuster into the powder dissolution tank 43 and performing water washing. Thereby, the water washing step S30 and the oxidation step S41 are performed in parallel.

[0122] By adjusting the pH during water washing to the acidic side, chlorine contained in the biomass ash B1 can be dissolved in water more efficiently compared to the case where the pH is not adjusted. In addition, the calcium component contained in the biomass ash B1 is easily reacted into the form of slowly reactive calcium carbonate or calcium sulfate added to the cement clinker Cn1 during cement production, and the modified biomass ash B2 obtained after the water washing step S30 is suitable as a cement admixture with small quality fluctuations.

[0123] As the pH condition of the slurry Lr1 in the oxidation step S41, it is preferably pH 4 to 13, and more preferably pH 5 to 12.

[0124] The pH adjuster is not particularly limited as long as it can adjust the pH of the slurry Lr1 to the acidic side, and examples thereof include acid solutions such as sulfuric acid and CO2-containing gases. As the CO2-containing gas, the combustion exhaust gas of the cement kiln 12, the combustion exhaust gas of the biomass incineration facility or the biomass power plant can be used. Since these exhaust gases contain carbon dioxide (CO2), the pH can be adjusted to the acidic side by blowing the combustion exhaust gas into the slurry Lr1. According to this, the calcium component contained in the biomass ash B1 is carbonated and more easily reacted into the form of calcium carbonate.

[0125] In FIG. 9B, as an example, the case where the CO2-containing gas G1 is supplied from the gas supply device 51 to the slurry Lr1 in the powder dissolution tank 43 is illustrated. In this case, the gas supply device 51 corresponds to the device for supplying the combustion exhaust gas of the cement kiln 12, the combustion exhaust gas of the biomass incineration facility or the biomass power plant, etc. to the powder dissolution tank 43, as described above.

[0126] The CO2-containing gas G1 only needs to contain carbon dioxide, but in order to promote efficient carbonation, the carbon dioxide concentration is preferably 10% or more, and more preferably 20% or more. Among the combustion exhaust gases, especially in the gas after collecting the chlorine bypass dust of the clinker production facility 10, harmful gases such as sulfur oxides (SO x ) are contained. Therefore, by blowing this gas into the slurry Lr1, the effect of immobilizing sulfur oxides can also be expected.

[0127] If the combustion exhaust gas of the clinker production facility 10 is used in this way, combustion exhaust gas containing carbon dioxide can be obtained on-site and used for the reforming of the biomass ash B1, and the reformed biomass ash B2 can be used as a cement admixture. Also, if the combustion exhaust gas of the biomass incineration facility or the biomass power plant is used, the biomass ash B1 can be reformed using the combustion exhaust gas containing carbon dioxide obtained on-site, and if this is transported to cement production facilities such as the clinker production facility 10 and the grinding facility 30, it can be immediately used as a cement admixture.

[0128] Furthermore, in the water washing step S30, waste liquid obtained from the amine-based carbon dioxide recovery device may be added to the powder dissolution tank 43 for water washing. In an amine carbon dioxide recovery device for recovering carbon dioxide from exhaust gas of a factory or the like, usually, the liquid containing deteriorated amines is discarded, but according to this method, the waste liquid can be effectively utilized.

[0129] Amines are known to react with carbon dioxide to promote the formation of carbonate ions, and can efficiently promote the carbonation of calcium components. Also, amines are known to function as a grinding aid when grinding cement clinker Cn1 in the primary grinding facility 30. Amines have an amino group and a hydroxyl group in the molecule. In particular, examples of amines used as a grinding aid include monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), diglycolamine (DGA), diisopropanolamine (DIPA), methyldiethanolamine (MDEA), and the like. Therefore, the modified biomass ash B2 incorporating amines brought in from the added waste liquid can be expected to be imparted with functionality as a grinding aid in the subsequent process, and thus is suitable as a cement admixture.

[0130] Note that it may be possible to blow the CO2-containing gas G1 into the dehydrated product Ck1 obtained through the dehydration step S33. According to this, the readily reactive calcium components remaining in the dehydrated product Ck1 are carbonated, and further homogenization of the quality of the obtained modified biomass ash B2 can be achieved, making it suitable as a cement admixture. Also, it helps in drying the moisture contained in the dehydrated product Ck1.

[0131] As the gas blowing means (gas supply device 51), it suffices that the dehydrated product Ck1 can be brought into contact with the CO2-containing gas, and the method is not limited. For example, means such as passing the CO2-containing gas through a container filled with the dehydrated product Ck1 or passing the dehydrated product Ck1 through the exhaust gas flue can be used. Also, similar to the blowing into the slurry Lr1 described above, the combustion exhaust gas of the cement kiln 12, the combustion exhaust gas of the biomass incineration facility or the biomass power plant can be blown into the dehydrated product Ck1.

[0132] This oxidation step S41 corresponds to step (f).

[0133] (Unburned carbon removal step S42) The unburned carbon removal step S42 is a step of removing unburned carbon contained in the biomass ash B1. Since the biomass ash B1 contains a large amount of unburned carbon, if it is used as a raw material for the cement clinker Cn1, it may cause the preheater 11 to become hotter, and if it is used as an admixture, it may cause the concrete to darken and the fluidity to decrease.

[0134] Specifically, when the water washing step S30 is executed, a method can be adopted in which a treatment such as stirring is performed in the powder dissolution tank 43 with the unburned carbon remover D1 such as oil or surfactant added from the unburned carbon remover supply device 52. The obtained slurry Lr2a is subjected to a flotation separation process in the flotation separation device 53 by adding, for example, a predetermined foaming agent, and is separated into a froth containing unburned carbon and a tail in which the unburned carbon is removed or reduced. Then, the slurry Lr2b as the tail is sent to the solid-liquid separation device 46 for solid-liquid separation.

[0135] Thereby, the water washing step S30 and the unburned carbon removal step S42 are performed in parallel and continuously.

[0136] This unburned carbon removal step S42 corresponds to step (g).

[0137] Note that the above-described oxidation step S41 and unburned carbon removal step S42 may be performed only on the fine powder B2F containing more calcium components and unburned carbon.

[0138] (Classification step S10) By adopting the same method as the method described above in the first embodiment, the modified biomass ash B2 is classified into the coarse powder B2C and the fine powder B2F.

[0139] Note that the water washing step S30 and the classification step S10 may be performed simultaneously with a wet classifier. Specifically, methods such as a sieve, a hydrocyclone, and centrifugation can be mentioned.

[0140] The activity index of the fine powder B2F obtained through the water washing process S30 and the classification process S10 is higher than that of the biomass ash (raw ash) B1, typically 70% or more at 7 days and 65% or more at 28 days, and more typically 73% or more at 7 days and 68% or more at 28 days.

[0141] The chlorine concentration of this fine powder B2F is reduced, for example, typically to 0.01% by mass to 0.2% by mass, and more typically to 0.02% by mass to 0.1% by mass.

[0142] The total alkali metal concentration of this fine powder B2F is reduced, for example, typically to 1% by mass to 8% by mass, and more typically to 3% by mass to 6% by mass.

[0143] The sulfur oxide concentration of this fine powder B2F is reduced, for example, typically to 0.5% by mass to 4% by mass, and more typically to 1% by mass to 3% by mass.

[0144] The elution amount of selenium in this fine powder B2F is reduced, for example, typically to 0.002 mg / L to 0.02 mg / L, and more typically to 0.005 mg / L to 0.01 mg / L.

[0145] The elution amount of hexavalent chromium in this fine powder B2F is reduced, for example, typically to 0.01 mg / L to 0.1 mg / L, and more typically to 0.02 mg / L to 0.05 mg / L.

[0146] The elution amounts of the above-mentioned selenium (Se) and hexavalent chromium (Cr 6+ ) can be measured by well-known methods. As a suitable example of the measurement method, after preparing a test solution in accordance with JIS K 0058-1 "Chemical Substance Test Method for Slags - Part 1: Elution Test Method 5. Test by Utilization Form", for selenium (Se), it is measured by ICP mass spectrometry, and for hexavalent chromium (Cr 6+ ), it is measured by diphenylcarbazide absorption photometry.

[0147] In addition, as shown in the embodiments described below, the content of calcium oxide and calcium hydroxide with high reactivity that affects the strength development and fluidity of cement is sufficiently reduced by the water washing step S30, and the calcium component is stabilized in the form of calcium carbonate, so that quality fluctuations can be suppressed.

[0148] For example, the content of calcium hydroxide in the modified biomass ash B2 after the water washing step S30 is typically 0.5% by mass or less, more typically 0.1% by mass or less.

[0149] In addition, for example, the content of calcium sulfate (gypsum) in the modified biomass ash B2 is typically 0.5% by mass or more in terms of SO3 conversion, more typically 3% by mass or more.

[0150] The above-mentioned chlorine concentration can be measured by a well-known method. For example, after acid decomposition treatment, a method of measuring by potentiometric titration is preferably exemplified.

[0151] In addition, the content of the above-mentioned calcium hydroxide can be measured by a well-known method. For example, a method of obtaining by measuring the heat quantity of dehydration near 400 °C by DSC (differential scanning calorimeter) is preferably exemplified.

[0152] In addition, the content of the above-mentioned calcium sulfate (gypsum) can be measured by a well-known method. For example, a method of quantifying by the Rietveld method from the X-ray powder diffraction pattern is preferably exemplified.

[0153] (Feeding step S20) The same method as the method described above in the first embodiment can be adopted. That is, for the feeding procedure, the coarse powder B1C in the first embodiment may be replaced with the coarse powder B2C obtained by performing the water washing step S30. In addition, in the present embodiment, in the feeding step S20, the fine powder B2F obtained through the water washing step S30 is also fed into the first grinding equipment 30.

[0154] In particular, in the present embodiment, since the water washing step S30 is executed before the charging step S20, the fine powder B2F obtained after classification may contain moisture as compared with the fine powder B1F obtained in the first embodiment. Therefore, the moisture contained in the fine powder B2F can be utilized for temperature control in the first grinding facility 30 for preventing the alteration of gypsum or the like. If the moisture contained in the fine powder B2F is excessive, it can be easily dehydrated by sedimentation separation or the like. Conversely, if the moisture is insufficient, an appropriate amount of water may be sprayed onto the grinding facility 30. The same applies to the coarse powder B2C.

[0155] Similar to what was described above in the first embodiment, the coarse powder B2C obtained after classification can also be directly charged into the clinker cooler 13. The temperature in the clinker cooler 13 is usually 200 to 1200 °C, and the heating temperature can be selected according to the charging position. However, when the above oxidation step S41 is executed, especially the modified biomass ash B2 contains a large amount of CaCO3 obtained by fixing CO2. In this case, it is preferable to charge it into the low-temperature part of 200 °C to 800 °C in the clinker cooler 13 so that the CaCO3 contained in the modified biomass ash B2 does not decompose to generate quicklime (CaO) or release carbon dioxide. As described above with reference to FIG. 4, it is also possible to charge the coarse powder B2C into the clinker cooler 13 after grinding it in the second grinding facility 35.

[0156] Note that although the alkali metal content of the modified biomass ash B2 obtained by the method of the present embodiment is reduced by executing the water washing step S30, it is still assumed that the alkali metal content is higher than that of coal ash. Therefore, when this modified biomass ash B2 is used as a raw material for the cement clinker Cn1, cement with a high alkali metal content may be produced. Also, the main component of the cement additive obtained from the waste water W3 is an alkali metal salt. Therefore, if these are contained in a large amount in the concrete, there is a possibility of causing an alkali-aggregate reaction depending on the aggregate.

[0157] Therefore, in order to reduce the possibility of alkali-aggregate reaction, it is also possible to add (introduce) latent hydraulic substances such as blast furnace slag, fly ash, pozzolanic substances such as volcanic ash, volcanic rock, and calcined clay together with the modified biomass ash B2. Note that the addition (introduction) of such latent hydraulic substances and pozzolanic substances is also applicable when using the coarse powder B1C in the case where the water washing step S30 is not performed as in the first embodiment. However, since the coarse powder B1C has a lower alkali metal content compared to the fine powder B1F, particularly when the fine powder B1F (B2F) is mixed with the cement raw material or cement, a high effect can be obtained by adding latent hydraulic substances and pozzolanic substances.

[0158] Further, the modified biomass ash B2 and a chlorine-containing substance are mixed, and the mixture is heated to form a chloride of an alkali metal. Further heating at a high temperature volatilizes and removes the chloride, or water is added to dissolve the alkali metal chloride, which is then removed by solid-liquid separation, thereby reducing the alkali metal concentration when used as a cement raw material.

[0159] [Third Embodiment] Regarding the third embodiment of the cement manufacturing method and the cement manufacturing system, the differences from the first and second embodiments will be mainly described. FIG. 10 is a drawing schematically showing the processing flow of the cement manufacturing method in this embodiment. FIG. 11A is a block diagram schematically showing the structure of the cement manufacturing system in this embodiment.

[0160] In this embodiment, compared with the second embodiment, the difference is that the water washing step S30 is performed after the classification step S10. In this embodiment, the water washing step S30 is performed only on the fine powder B1F classified by the classification step S10. In the example of FIG. 11A, the case where the fine powder B2F after the water washing treatment is input into the cement manufacturing facility 10 is shown. Also, in the example of FIG. 11A, the coarse powder B1C obtained after the classification treatment is input into the cement manufacturing facility 10 or the first pulverizing facility 30 without being washed with water.

[0161] When comparing the coarse powder B1C and the fine powder B1F obtained by classifying the biomass ash B1 in the classification step S10, more chlorine is contained in the fine powder B1F than in the coarse powder B1C. Therefore, according to the present embodiment, cement-repellent components such as chlorine contained in the biomass ash B1 can be efficiently reduced while reducing the amount of water required for carrying out the water washing step S30.

[0162] As a specific method for introducing the washed fine powder B2F into the cement production facility 10, as in the case of the coarse powder B1C, it can be introduced into the raw material preparation system equipment such as a mixer or crusher for preparing the raw materials of the cement clinker, into the preheater top or calciner before the cement kiln, into the cement kiln kiln end, into the high-temperature part before the cement kiln (rotary kiln), and the like. Although the fine powder B1F contains chlorine and sulfur at a higher concentration than the coarse powder B1C, since the content concentrations of chlorine and sulfur contained in the biomass ash B1 are reduced by water washing, it can be utilized as a raw material for the cement clinker Cn1.

[0163] As a result, clogging due to the adhesion of low-melting substances to the preheater, kiln end, and kiln is suppressed compared to the case where no water washing is performed, and the chlorine content of the cement clinker Cn1 is also reduced. In addition, the alkali metal content of the cement clinker Cn1 increases, and high-strength cement can be obtained. In particular, when the coarse powder B1C is introduced as a cement admixture, or when latent hydraulic substances such as blast furnace slag, pozzolanic substances such as fly ash, volcanic ash, volcanic rock, and calcined clay are added, the reaction of these admixtures is activated by the alkali metal supplied from the cement clinker.

[0164] Also in the present embodiment, similar to the second embodiment, the oxidation step S41 and the unburned carbon removal step S42 may be executed. Since the others are common to the above-described embodiments, the description thereof is omitted.

[0165] Note that, as shown in FIG. 11B, the washed fine powder B2F may be introduced into the first pulverizing facility 30 and pulverized and mixed together with the cement clinker Cn1.

[0166] [Alternative Embodiment] The following describes an alternative embodiment.

[0167] 〈1〉 As shown in FIG. 12, among the coarse powder B1C and the fine powder B1F obtained by classifying the biomass ash B1 in the classification facility 20, the coarse powder B1C may be washed by the washing facility 40. Although the concentration of chlorine and sulfur in the coarse powder B1C is reduced by the classification step S10, the concentration of these is further reduced by performing the washing step S30. Therefore, it can be used as a raw material for the cement clinker Cn1. As shown in FIG. 12, the washed coarse powder B2C after this washing treatment may be put into the first grinding facility 30 in addition to the cement manufacturing facility 10. Also, as in the example shown in FIG. 4, after the washed coarse powder B2C is ground by the second grinding facility 35, it may be put into the cement manufacturing facility 10.

[0168] Since the waste water W3 obtained in the washing step S30 is obtained after washing the coarse powder B1C with little chlorine, the content chlorine concentration is in a low state. Therefore, the waste water W3 may be mixed with the cement clinker Cn1 without taking measures to reduce the contained chlorine ions as described in the second embodiment.

[0169] On the other hand, for the fine powder B1F, after separately performing a washing treatment as necessary, it may be mixed with the cement clinker Cn1 or cement, or may be used as a fertilizer or fine aggregate.

[0170] 〈2〉 In each of the above embodiments, the process until cement is manufactured by grinding the cement clinker Cn1 in the grinding facility 30 has been described. However, as the charging step S20, the coarse powders (B1C, B2C) of the biomass ash obtained in each embodiment may be used in a method for manufacturing a cement hardened product such as concrete or mortar by charging and kneading them with cement and water. [Example]

[0171] [Example 1] Incineration fly ash BA-1 (particle size D 50 (frequency) is 47.2 μm, and the ignition loss at 975 °C is 4.17%) was obtained from the biomass power generation facility P1 that uses palm coconut shells as fuel and generates electricity by a circulating fluidized bed furnace, and the effect on the component composition of biomass ash by classifying this was examined. The coal content in the mixed fuel of palm coconut shells and coal was 10% by mass. The particle size distribution of this incineration fly ash (using a laser diffraction particle size distribution measuring device: MT3300EX II manufactured by Microtrac Bell) is as shown in Fig. 3.

[0172] 《Test method》 The test method will be described below.

[0173] 〈1. Classification〉 Using a sieve with an aperture size set to be the classification point shown in Table 1 (spin air sieve: SAR-75 / 200 manufactured by Seishin Enterprise Co., Ltd.), the sample was sieved, and fine powder B1F was obtained as the fraction passing through the sieve, and coarse powder B1C was obtained as the residue on the sieve. This process corresponds to the classification step S10. This classification point was set based on the particle size distribution shown in Fig. 3. In the test, biomass ash B1 was classified at three classification points of 32 μm, 45 μm, and 90 μm, respectively. In the following, in order to clarify that biomass ash B1 is before classification, it may be denoted as "raw ash B1".

[0174] The particle size distribution of the biomass ash after classification is as shown in Table 1. In Table 1, the coarse powder B1C obtained after classifying incineration fly ash BA-2 obtained from a biomass power generation facility P2 different from the biomass power generation facility P1 with 45 μm as the classification point is also shown. The particle size distribution was measured by a laser diffraction particle size distribution measuring device (MT3300EX II manufactured by Microtrac Bell).

[0175]

Table 1

[0176] 〈2. Chemical Composition Analysis〉 For the raw ash B1 (#1) derived from incineration fly ash BA-1, each coarse powder B1C (#2, #4), and each fine powder B1F (#3, #5), and the raw ash B1 wet-ashed by the following method (#1W), and the coarse powder B1C (#2W) obtained by classifying the wet-ashed raw ash B1 (#1W) at 45 μm, the chemical components were measured. Also, the coarse powder B1C (#9) and the fine powder B1F (#10) obtained by classifying the raw ash B1 with a classification point of 20 μm were obtained, and the chemical components were measured in the same way for these. Furthermore, for the raw ash B1 (#1) and the fine powder B1F (#3) classified at 45 μm, those subjected to a water washing treatment by the following method were prepared (#1Wp, #3Wp), and the chemical components were measured in the same way.

[0177] The method of wet-ashing is as follows. For the raw ash B1 (symbol #1), 20% by mass (water content 16.7% by mass) of water was added by external division, then stored at 20 °C for 3 days, and dried at 105 °C to obtain wet ash. The raw ash B1 wet-ashed by this method corresponds to "symbol #1W", and the coarse powder B1C obtained by classifying this wet-ashed raw ash #1W corresponds to "symbol #2W". When classifying the wet-ashed raw ash B1 (#1W), an air jet sieve (manufactured by Hosokawa Micron Corporation, e200LS) was used.

[0178] The method of water washing treatment is as follows. This treatment corresponds to the water washing step S30. (Procedure 1) 100 g of biomass ash (B1, B1F) and 400 g of tap water were put into a beaker to make a slurry, and stirred at 400 rpm for 30 minutes with a stirrer. At this time, when adjusting the pH by flowing CO2 gas during water washing, the flow rate was adjusted while monitoring the pH in the liquid with a pH meter. (Procedure 2) After stopping the stirring, filtration was carried out using a Buchner funnel, 400 g of tap water was further added to the cake on the obtained filter paper to wash the slurry, and then it was recovered. (Procedure 3) The recovered cake was naturally dried, its mass was measured, and various analyses were carried out.

[0179] In addition, the obtained coarse powder was pulverized using a ball mill.

[0180] 《Analysis》 The chemical components were measured by the following method. For each of the prepared samples (#1 to #5, #9 to #10, #1W, #2W, #1Wp, #3Wp), the chemical components were measured by the calibration curve (coal ash) method using a fluorescent X-ray apparatus (ZSX Primus II manufactured by Rigaku Corporation). The results are shown in Table 2. The loss on ignition of each sample was measured by a method conforming to JIS R 5202 "Chemical Analysis Method of Cement". In addition, the amount of calcium carbonate in the incineration fly ash and the obtained sample was determined by obtaining the mass reduction amount in the vicinity of 600°C to 700°C when heating about 50 mg of the sample at a heating rate of 20°C / min to 1000°C in a nitrogen atmosphere, and calculating the ratio to the weight reduction with the reagent (using TG-DTA 2000SR manufactured by NETZSCH). The amount of calcium hydroxide in the incineration fly ash and the obtained sample was determined by obtaining the endothermic amount near 400°C when heating about 50 mg of the sample at a heating rate of 10°C / min to 1000°C in a nitrogen atmosphere, and calculating the ratio to the weight reduction with the reagent (using DSC404F3 manufactured by NETZSCH).

[0181] The amount of hydrate formed was obtained by subtracting the decarbonation component volatilized from the amount of calcium carbonate from the loss on ignition. The amount of hydrate formed in the raw ash B1 was 1.8%, and that in the wet-ashed sample (#1W) was 6.0%.

[0182]

Table 2

[0183] According to Table 2, when the raw ash B1, which is dry ash, is classified with the point between the peak on the fine-grain side and the peak on the coarse-grain side when the particle size distribution is represented by frequency as the classification point, most of the chlorine component and sulfur component (SO3) are contained on the fine powder (B1F) side. Also, it was confirmed that the chlorine component could be efficiently removed by washing this (B2F). Therefore, it can be seen that the fine powder after washing is particularly suitable as a cement admixture.

[0184] On the one hand, the reduction amount of alkali metals on the side of the coarsely ground powder (B1C) obtained by classifying the raw ash is small, and it contains almost no chlorine component and sulfur component. Moreover, compared with the raw ash, CaO has decreased and SiO2 has increased. Therefore, it can be seen that the coarsely ground powder is close to the chemical composition of coal ash and is suitable as a raw material for cement clinker.

[0185] Also, when comparing the raw ash B1 wet-ashed (#1W) with the coarsely ground powder B1C (#2W) obtained by classifying this at 45 μm, it is confirmed that the degree of reduction in chlorine concentration due to classification is low. This is presumably because agglomeration and hydration reactions occurred due to the wet-ashing of the raw ash B1, and the chlorine (Cl) component was incorporated into the generated hydrate, resulting in a decrease in the removal rate by classification. The raw ash B1 wet-ashed (#1W) had a hydration reaction, and the loss on ignition was increased compared to the dry raw ash B1.

[0186] 〈3. Physical Tests〉 For the raw ash B1 (#1), coarsely ground powder B1C (#2), and finely ground powder B1F (#3) derived from the incineration fly ash BA-1, with a classification point of 45 μm, the Blaine specific surface area, flow value ratio, and activity index were measured by a method conforming to Appendix C of JIS A 6201 "Fly Ash for Concrete". Furthermore, the coarsely ground powder B1C (#2) was ground with a mill to have a particle size comparable to that of the finely ground powder B1F, and the Blaine specific surface area, flow value ratio, and activity index were measured in the same way. Note that the ground product (#2C) obtained by grinding the coarsely ground powder B1C is, for example, in Fig. 12, a simulation of the coarsely ground powder B1C after classification being ground by the grinding equipment 30 (conveniently referred to by the symbol "B1Cp"). The measurement results are shown in Table 3.

[0187]

Table 3

[0188] According to Table 3, when the fine powder B1F obtained by classifying the raw ash B1 was used as a blending material, it was confirmed that the activity index was higher than that of the raw ash B1. Note that the coarse powder B1C does not contain chlorine, and it has been clarified that if it is pulverized until the Blaine specific surface area becomes 4000 cm 2 / g or more (B1Cp), it can be used as a pozzolanic blending material with higher reactivity than the raw ash.

[0189] [Example 2] Fly ash (particle size D 50 (frequency) of 45.3 μm and ignition loss (ig.loss) of 2.3% at 750 °C) was obtained from the biomass power generation facility P2 that performs power generation using woody biomass (thinned wood) as fuel in a circulating fluidized bed furnace, and this was washed with water, and the influence of the presence or absence of an oxidation process (particularly a carbonation process) during this water washing on the component composition was examined.

[0190] 《Test method》 The test was conducted according to the following procedure. (Procedure 1) 100 g of biomass ash and 400 g of tap water were put into a beaker to make a slurry, and it was stirred at 400 rpm for 30 minutes with a stirrer. At this time, when adjusting the pH by flowing CO2 gas during water washing, the flow rate was adjusted while monitoring the pH in the liquid with a pH meter. (Procedure 2) After stopping the stirring, filtration was carried out using a Buchner funnel, and 400 g of tap water was further added to the cake on the obtained filter paper to wash the slurry, and then it was recovered. (Procedure 3) The recovered cake was naturally dried, its mass was measured, and various analyses were performed.

[0191] Table 4 below shows the levels of each water washing condition.

[0192]

Table 4

[0193] 《Analysis》 For the obtained samples, analysis was performed by the following methods respectively. Quantification of Cl: After subjecting the sample to nitric acid decomposition treatment, it was measured by potentiometric titration. Quantification of K and Na: After subjecting the sample to acid decomposition treatment, it was measured by ICP emission spectrometry. Elution test of Se and Cr 6+ : After preparing the test solution by a method compliant with JIS K 0058-1 "Test Methods for Chemical Substances in Slags - Part 1: Elution Test Method 5. Test by Utilization Form", for Se, it was measured by ICP mass spectrometry, and for Cr 6+ was measured by diphenylcarbazide absorptiometry respectively. Quantification of C, Mg, Al, Si, P, S, Ca, and Fe: The sample subjected to drying treatment at 40 °C was measured by a fluorescent X-ray apparatus (FP method: fundamental parameter method). The measurement results are shown in Tables 5 and 6.

[0194]

Table 5

[0195]

Table 6

[0196] According to Table 5, it was confirmed that most of the chlorine was effectively removed by washing the raw ash with water, and when used as a blending material, after the cement was water-hardened, it satisfied the allowable standard of 0.035 mass% or less, which was evaluated as having no risk of corrosion to steel bars, etc. That is, when the biomass ash after washing was classified, it was found that almost no chlorine was contained in both the fine powder side and the coarse powder side.

[0197] Also, according to Table 5, it was clarified that the water-soluble selenium and hexavalent chromium contained in the raw ash were also effectively removed by washing with water, and the risk of elution of heavy metals when used as a blending material was reduced.

[0198] As shown in Table 6, it was clarified that this biomass ash has SiO2 and CaO as the main components and is useful as a highly reactive pozzolanic blending material.

[0199] According to the results of Level 2-2, it was revealed that by performing water washing while blowing CO2 gas, the CO2 content rate of the biomass ash after water washing increased. Therefore, it is considered that at least a part of the components for pH adjustment was immobilized in the ash after the water washing operation, and calcium carbonate was generated. Also, by performing water washing while blowing CO2 gas, calcium hydroxide disappeared. In Table 5, the calcium hydroxide content being less than 0.01% means that it is below the detection limit.

[0200] Table 7 below shows the results of examining the existing form of calcium components in the ash by the XRD method (X-ray diffraction method).

[0201]

Table 7

[0202] According to Tables 6 and 7, in the raw ash, the presence of each Ca compound of CaO (quicklime), Ca(OH)2 (slaked lime), CaCO3 (limestone), and CaSO4 (gypsum) was confirmed as the form of calcium components. In contrast, in Level 2-1 where water washing was performed without pH adjustment, the presence of CaO (quicklime) disappeared, and a decrease in the presence of Ca(OH)2 (slaked lime) was confirmed. Also, in Level 2-2 where water washing was performed at pH 9 while blowing CO2 gas, it was confirmed that the presence of CaO (quicklime) and Ca(OH)2 (slaked lime) disappeared and calcium carbonate increased.

[0203] [Example 3] Incineration fly ash (particle size D 50 (frequency) of 20.0 μm, ignition loss (ig.loss) of 6.1% at 750 °C) was obtained from the biomass power generation facility P3 that performs power generation using a stoker furnace with wood pellets and palm coconut shells as fuel, and the same test as in Example 2 was conducted. The results are shown in Tables 8 and 9. Note that in Level 3-2, sulfuric acid for pH adjustment was added during water washing.

[0204]

Table 8

[0205]

Table 9

[0206] According to Table 8, most of the chlorine is effectively removed by washing the raw ash with water. After the cement used as a admixture is water-hardened, it is confirmed that the allowable standard of less than 0.035% by mass, which is evaluated as having no risk of corrosion to steel bars etc., is satisfied. That is, when the biomass ash after washing with water is classified, it can be seen that almost no chlorine is contained in both the fine powder side and the coarse powder side.

[0207] Also, according to Table 8, the water-soluble selenium and hexavalent chromium contained in the raw ash are also effectively removed by washing with water, and it has become clear that the risk of elution of heavy metals when used as an admixture is reduced.

[0208] As shown in Table 9, it has become clear that this biomass ash has SiO2 and CaO as main components and is useful as a highly reactive pozzolan admixture.

Explanation of Signs

[0209] 1: Cement manufacturing system 3: Raw material tank 5: Powder storage tank 10: Clinker manufacturing equipment 11: Preheater 12: Cement kiln 13: Clinker cooler 20: Classification equipment 30: First grinding equipment 35: Second grinding equipment 40: Washing equipment 41: Powder supply device 42: Liquid supply device 43: Powder dissolution tank 44: Slurry stirring device 46: Solid-liquid separation device 47: Conveyor device 49: Water washing device 51: Gas supply device 52: Unburned carbon agent supply device 53: Flotation separation device B1: Biomass ash B1C: Coarse powder B1F: Fine powder B2: (Modified) biomass ash B2C: (Modified) coarse powder B2F: (Modified) fine powder Ck1: Dewatered product Cn1: Cement clinker D1: Unburned carbon agent G1: CO2-containing gas Lr1: Slurry Lr2(Lr2a, Lr2b): Slurry W1, W2: Water W3: Drainage water Y1: Cement clinker raw material

Claims

1. Biomass ash stored in a powder storage tank, with a K 2 content rate of 2% to 10% by mass, is classified into coarse powder and fine powder with a classification point of 20 µm or more and 100 µm or less (step (a)); The cement production method is characterized by having a step (b) of charging the coarse powder obtained in the step (a) into at least one of a cement clinker raw material charged into a cement kiln, the cement clinker obtained from the cement kiln, or cement after being pulverized with respect to the cement clinker.

2. It has a step (c) of charging the fine powder obtained in the step (a) into at least one of the cement clinker or cement after being pulverized with respect to the cement clinker. The cement production method according to claim 1, wherein the step (b) is a step of charging the coarse powder obtained in the step (a) into a cement clinker raw material charged into a cement kiln.

3. It has a step (c) of charging the fine powder obtained in the step (a) into the cement clinker raw material. The cement production method according to claim 1, wherein the step (b) is a step of charging the coarse powder obtained in the step (a) into a cement clinker raw material charged into a cement kiln.

4. It has a step (d) of washing the biomass ash with water. The cement production method according to claim 2 or 3, wherein the step (c) is a step of charging the fine powder after being washed with water by the step (d).

5. The cement production method according to claim 4, wherein the step (d) is a step of washing only the fine powder obtained in the step (a) with water.

6. During the execution of the step (d) or after the execution of the step (d), the biomass ash is subjected to an oxidation treatment The cement production method according to claim 4 or 5, characterized by having a step (f).

7. It has a step (e) of pulverizing at least a part of the coarse powder obtained in the step (a). The cement production method according to any one of claims 1 to 6, wherein the step (b) is a step of charging the coarse powder after being pulverized by the step (e) into the cement clinker obtained from the cement kiln or cement after being pulverized with respect to the cement clinker.

8. The cement production method according to any one of claims 1 to 7, wherein the biomass ash is fly ash generated from a fluidized bed combustion furnace and is dry ash.

9. K 2 A powder storage tank for storing biomass ash with a K content of 2% to 10% by mass, A classification facility for classifying the biomass ash into coarse powder and fine powder using 20 μm or more and 100 μm or less as the classification point. A cement kiln for firing cement clinker raw materials to produce cement clinker, and a first pulverizing facility for pulverizing the cement clinker obtained from the cement kiln to produce cement, comprising: A cement manufacturing system, wherein the coarse powder obtained by the classification facility is introduced into at least one of the cement clinker raw materials, the cement clinker obtained from the cement kiln, or the cement obtained from the first pulverizing facility.

10. The cement manufacturing system according to claim 9, wherein the coarse powder obtained by the classification facility is introduced into the first pulverizing facility.

11. A second pulverizing facility for pulverizing the coarse powder classified by the classification facility, The cement manufacturing system according to claim 9, wherein the coarse powder after being pulverized by the second pulverizing facility is introduced into at least one of the cement clinker obtained from the cement kiln or the cement obtained from the first pulverizing facility.

12. Biomass ash stored in a powder storage tank, with a K 2 content of 2% to 10% by mass, is classified into coarse powder and fine powder with a classification point of 20 µm or more and 100 µm or less in a step (a); A step (e) of pulverizing the coarse powder obtained in the step (a); A method for manufacturing a hardened cement product, comprising: a step (b) of introducing the pulverized coarse powder obtained in the step (e), the cement after the pulverization treatment, and water.

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