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

Abstract

To provide a cement production method and a cement production system capable of effectively utilizing biomass ash while suppressing deterioration in strength of a formed cement hardened material.SOLUTION: A cement production method comprises a step (a) for classifying biomass ash into coarse powders and fine powders, and a step (b) for charging the fine powders obtained in the step (a) to at least any one of cement clinker raw material to be charged to a cement kiln, cement clinker obtained from the cement kiln, or cement after crushing treatment of 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 by various business entities 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. Therefore, it is expected that biomass ash can be recycled as a cement raw material or the like, similar to incineration ash such as municipal waste.

[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]

Non-Patent Document 1

[1307]

Summary of the Invention

Problems to be Solved by the Invention

[0005] In Non-Patent Document 1 above, biomass ash is used as it is as a cement admixture. However, according to this method, there is a problem that the strength of cement hardened products such as concrete and mortar using the obtained cement is significantly reduced.

[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 a decrease in the strength 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 fine powder obtained in the step (a) into at least any 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 on the cement clinker.

[0008] Although biomass ash has low activity, the finer the particle size, the higher the activity and the higher the alkali metal content. Therefore, as in the above method, the fine powder obtained after classifying biomass ash is mixed with a cement clinker raw material, a cement clinker (hereinafter, both may be collectively referred to as "cement raw materials"), or cement, thereby activating the pozzolanic reaction. Therefore, the strength of the hardened cement product is increased as compared with the case where the biomass ash before classification (hereinafter, referred to as "raw ash") is introduced into the cement raw material or cement.

[0009] Specific methods of the step (b) include charging into raw material preparation system equipment such as a mixer or crusher for preparing the raw material of cement clinker, charging into the preheater top or calciner before the cement kiln (rotary kiln), charging into the kiln end of the cement kiln, charging into the front of the cement kiln, charging into the clinker cooler for cooling the cement clinker obtained by firing, charging into a pulverizing device (mill) for pulverizing the cement clinker, charging into a mixer for producing blended cement, charging into a concrete mixer, and the like. That is, the fine powder of biomass ash obtained in the step (a) can be charged at various stages during cement production and can be suitably used as a cement clinker raw material, a cement admixture, or a cement extender.

[0010] In the following, for the purpose of avoiding redundancy by describing "admixture or blending material" in this specification, when simply described as "admixture", it shall refer to the material input to cement clinker or cement regardless of the cement manufacturing stage.

[0011] This step (a) is preferably carried out on biomass ash (preferably dry ash) in a state where water has not been added and the hydration reaction has not proceeded. 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.

[0012] In this specification, "dry ash" refers to the biomass ash recovered in a dried state, to which water has not been added until the classification process is carried out, and which has not aggregated or formed hydrates. Further, even if water is added before the classification process, the dry ash is in a state where a large amount of water is added and dispersed, and includes cases where no hydrates are formed due to long-term storage. Also, in this specification, "wet ash" refers to, for example, the main ash which is the incineration residue discharged from the bottom of the incinerator or the fly ash recovered by a dust collector or the like, which is recovered in a state containing moisture by water cooling or watering, or the dried product thereof. Generally, the wet ash has a moisture content of 15% by mass or more.

[0013] The cement manufacturing method includes a step (c) of washing the biomass ash with water. The step (b) may be a step of inputting the fine powder after being washed with water in the step (c).

[0014] According to the studies by the present inventors, biomass ash contains components that are harmful in cement and concrete, and the presence of highly reactive calcium components results in poor quality stability, so there was a concern that resource utilization as a cement raw material or the like would be restricted. On the other hand, according to the above method, since the biomass ash that has undergone the water washing step (c) is put into a cement raw material (cement clinker raw material, cement clinker) or cement, the chlorine, which is a cement-repellent component, is efficiently removed from the biomass ash to be put in, and the corrosion of the reinforcing bars of the concrete as a cement hardened product can be suppressed. In addition, heavy metals such as selenium and chromium, which may cause environmental pollution, and highly reactive calcium oxide and calcium hydroxide are removed, and the quality of the cement can be homogenized. When the biomass ash that has undergone the water washing step (c) is used as a clinker raw material, clogging due to the adhesion of low-melting substances to the preheater, the kiln end, and the kiln is suppressed.

[0015] This water washing step (c) preferably includes a step (c1) of adding water to the biomass ash to make a slurry, a step (c2) of supplying washing water to the slurry for water washing, and a step (c3) of dehydrating the slurry after water washing. By making a slurry, then washing with water, and then dehydrating, chlorine and heavy metals can be removed to obtain a dehydrated product.

[0016] The step (c) may be such that only the fine powder obtained in the step (a) is washed with water.

[0017] According to the studies 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 contained 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.

[0018] The cement production method may include a step (d) of oxidizing the biomass ash during or after the execution of the step (c).

[0019] According to the above method, since the pH during water washing is adjusted to the acidic side, chlorine can be removed more efficiently. Further, even when a large amount of highly reactive calcium oxide or calcium hydroxide is contained in the biomass ash, it can be completely replaced with calcium carbonate or calcium sulfate, so that the quality such as the fluidity of the cement can be homogenized.

[0020] As step (d), an acid solution may be added during the water washing of the biomass ash, or a carbon dioxide (CO2)-containing gas may be blown in, or a CO2-containing gas may be blown into the biomass ash after the water washing treatment. In particular, by using the combustion exhaust gas of the cement kiln, the extraction gas of the chlorine bypass, or the combustion exhaust gas of the biomass incineration facility or biomass power plant as the CO2-containing gas, the CO2 contained in these gases can be changed to calcium carbonate and fixed in the biomass ash, so that 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 in the biomass ash.

[0021] Further, particularly in step (d), by carbonating the biomass ash during the water washing according to step (c), the calcium content contained in a large amount in the waste liquid after water washing can be precipitated as calcium carbonate, so that the generation of scale is suppressed. Thereby, it is possible to suppress the blockage of pipes and the like for wastewater treatment.

[0022] The cement production method may also have a step (e) of removing unburned carbon contained in the biomass ash during the execution of step (c).

[0023] The biomass ash may contain a lot of unburned carbon. Therefore, when using biomass ash containing a lot of carbon as a cement clinker raw material, there is a risk of increasing the temperature of the preheater, and when using it as a mixing material, there is a risk of blackening of the concrete or a decrease in fluidity due to the adsorption of the water reducing agent to the carbon.

[0024] On the other hand, according to the above method, unburned carbon can be removed during water washing, so that the occurrence of the above-described problems can be suppressed. Specifically, it is possible to reduce the amount of unburned carbon contained by performing flotation by mixing a carbon-removing agent such as oil or surfactant.

[0025] The step (b) may be a step of charging at least one of the cement clinker obtained from the cement kiln or the cement after the grinding treatment of the cement clinker.

[0026] According to this method, since the fine powder obtained after classifying the biomass ash is used as a mixing material, the strength of the cement hardened body becomes higher than when the biomass ash before classification is used as a mixing material.

[0027] The step (b) may also be a step of mixing at least one of a latent hydraulic substance and pozzolan in addition to the fine powder.

[0028] When the fine powder after classifying the biomass ash is charged 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 the alkali metals to generate water-absorbing alkali-silica gel, which may cause cracks in the concrete (alkali-aggregate reaction).

[0029] On the other hand, according to the above method, since a latent hydraulic substance such as blast furnace slag or pozzolan (including natural pozzolan such as silica powder and stone powder, and artificial pozzolan such as fly ash and calcined clay) is charged together with the fine powder, the alkali-aggregate reaction can be suppressed.

[0030] 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.

[0031] 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. Thereby, since chlorine and sulfur are dominantly distributed to the fine powder side in particular, it is efficient.

[0032] The cement production system according to the present invention a classification facility 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 a pulverizing facility for pulverizing the cement clinker obtained from the cement kiln to produce cement, characterized in that the fine powder obtained by the classification device is introduced into at least any one of the cement clinker raw material, the cement clinker obtained from the cement kiln, or the cement obtained from the pulverizing facility.

[0033] According to the above system, since the fine powder obtained after classifying biomass ash is introduced into the cement raw material or cement, the strength of the cement hardened product can be increased as compared with the case where the raw ash is mixed with the cement raw material or cement.

[0034] Also, the method for producing a cement hardened product according to the present invention has a step (a) of classifying biomass ash into coarse powder and fine powder, and a step (b) of introducing the fine powder obtained in the step (a), the cement after pulverization treatment, and water.

[0035] Also by this method, for the same reason as described above, a cement hardened product with higher strength can be obtained than when the raw ash before classification is introduced. Examples of the cement hardened product include concrete and mortar. In any case, in addition to the fine powder, cement, and water, appropriate aggregates may be appropriately introduced. After these are introduced, they may be mixed, for example, in a concrete mixer.

Effects of the Invention

[0036] According to the present invention, it is possible to effectively utilize biomass ash in cement production while suppressing a decrease in the strength of the produced cement hardened body.

Brief Description of the Drawings

[0037]

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Embodiments for Carrying Out the Invention

[0038] [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.

[0039] The biomass ash to which the present invention is applied includes generally incineration ash of biomass widely, 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 an advantage that the proportion of alkali metal sulfates and alkali metal carbonates is larger and the concentration of alkali chlorides is lower than that of municipal solid waste incineration ash and chlorine bypass dust.

[0040] Since biomass ash is incineration ash, it contains a glass component having pozzolanic reactivity similar to coal ash. Among biomass ash, the incineration ash of plants, bamboo has a relatively high content of K2O, and more than half of potassium (K2O) is embedded and contained in its glass phase. Therefore, since biomass ash has high activity when used as a blending material, it is preferably used in cement manufacturing.

[0041] The content of K2O in biomass ash is preferably 2% by mass to 10% by mass, more preferably 3% by mass to 8% by mass, and even more preferably 3% by mass to 5% by mass. If the K2O content of biomass ash is less than 2% by mass, the strength of cement when used as a blending material may be reduced, and there is also a possibility that the required amount as a material to be added to 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 when used as a blending material may increase.

[0042] The total alkali concentration contained in the biomass ash is preferably 2% to 11% by mass, more preferably 3% to 6% by mass, in terms of R2O conversion (R2O = Na2O + 0.658 × K2O). Further, the sulfur oxide (SO3) concentration contained in the biomass ash is preferably 0.5% to 6% by mass, more preferably 1% to 5% by mass.

[0043] In biomass power plants, co-firing of biomass and coal may be carried out. However, the biomass ash to which the present invention is applied includes ash generated when such co-firing is carried out. Generally, coal ash from burning coal has a low K2O content, so the activity of the biomass ash varies depending on the amount of coal used during co-firing. Therefore, from the perspective of recycling as an admixture in cement production, when it is co-firing with coal, it is preferable that the ash is obtained from those with a biomass ratio of 50% by mass or more in the fuel.

[0044] As the biomass ash to which the present invention is applied, palm kernel shell ash (PKS ash) obtained using palm kernel shells as fuel among the incineration ashes of grass, wood, and bamboo is also preferably exemplified. Palm kernel shells are by-products of palm oil production and are mainly used in the natural biomass energy industry. Palm kernel shells are yellowish-brown fibrous substances with little ash content, having a particle size of about 5 mm to 40 mm and a calorific value of about 4000 Kcal / kg. Therefore, in energy production using renewable resources, the use of palm kernel shells as fuel for biomass power generation has been increasing in recent years.

[0045] 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 components and sulfur components. For example, the CaO content rate is generally 5% to 45% by mass. Further, 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.

[0046] The CaO content of the biomass ash to which the present invention is applied is preferably 10% by mass to 40% by mass, more preferably 15% by mass to 30% by mass, from the viewpoint of the strength of cement when it is recycled as an admixture.

[0047] As the type of ash of the biomass ash to which the present invention is applied, it may be the main ash remaining at the bottom of a combustion furnace for biomass power generation or the like, or fly ash obtained by collecting dust floating as a gas in the combustion exhaust gas with a dust collector. Among these, fly ash is preferable because it has a higher concentration of alkali metals and chlorine and chlorine is more easily separated by washing with water, which is efficient.

[0048] Also, the biomass ash is preferably dry ash. Biomass ash that has been sprayed with water once may become granular, or chlorine may be incorporated into the generated hydrate, making it difficult to separate chlorine by classification or washing with water. As dry ash, for example, it is preferable that Friedel's salt or ettringite, which are hydrates, are 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.

[0049] 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.

[0050] The particle size of the biomass ash is, for example, such that 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 particle size distribution measuring device. For example, it can be measured by using ethanol as a dispersion medium with a Microtrac Bell MW3300EXII and measuring after 1 minute of ultrasonic dispersion. Note that D 50 The value means the particle size at 50% cumulative volume in the volume-based particle size distribution.

[0051] [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.

[0052] The cement manufacturing system 1 shown in FIG. 2 includes a raw material tank 3 in which the cement clinker raw material Y1 is stored, a powder storage tank 5 in which the biomass ash B1 is stored, a clinker manufacturing facility 10, a classification facility 20, and a pulverization facility 30. The clinker manufacturing facility 10 is a facility for firing the cement clinker raw material Y1 to generate the 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 fired cement clinker Cn1.

[0053] As shown in FIG. 1, the cement manufacturing method of this embodiment has a step S10 of classifying the biomass ash B1 and a step S20 of charging or adding the classified biomass ash B1 to the cement raw material or the like. Hereinafter, the charging or adding step will be collectively referred to as the "charging" step.

[0054] (Classification Step S10) The biomass ash B1 stored in the powder storage tank 5 is classified by the classification equipment 20 into coarse powder B1C with a coarse particle size and fine powder B1F with 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.

[0055] The classification equipment 20 is not particularly limited as long as it can classify the biomass ash B1 at a classification point on the order of μm as described above. For example, sieves, inertial classification devices, centrifugal classification devices, gravity classification devices, etc. can be preferably used. From the viewpoint of classification accuracy in particular, the use of a cyclone type air separator, a sieving device, etc. is preferable. When performing water washing, it is efficient to perform it wet.

[0056] In the incinerator of the fluidized bed type, sand mainly composed of quartz as a fluidizing medium and limestone for desulfurization are charged. Therefore, the fly ash of the biomass ash from such an incinerator contains relatively coarse molten and solidified or agglomerated glass and sand-derived substances, and relatively fine volatile alkali metal salts and the aforementioned limestone-derived substances. Therefore, when the classification point is set between the peak on the fine particle side and the peak on the coarse particle side when the particle size distribution of the biomass ash is represented by frequency, chlorine, sulfur, and calcium components can be efficiently separated.

[0057] 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 with the particle size in the region (valley region) between these peaks as the classification point, chlorine, sulfur, and calcium components can be efficiently separated.

[0058] The classification equipment 20 may be provided with a storage tank for biomass ash B1. Further, a supply device for quantitatively supplying the biomass ash B1 from such a storage tank to the classification equipment 20 may be provided. These storage tanks and supply devices may be appropriately used according to the state of the received biomass ash B1.

[0059] 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, calcium oxide concentration, etc. of the fine powder B1F and the coarse powder B1C.

[0060] 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 at 7 days and 65% or more at 28 days, and more typically 75% or more at 7 days and 70% or more at 28 days.

[0061] 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 JIS A 6201:2015 "Fly ash for concrete" is preferably exemplified.

[0062] The yield of the fine powder B1F is preferably 10% to 80%, more preferably 20% to 70%, and even more preferably 30% to 60%. The yield of the fine powder B1F may be 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.

[0063] 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 even more preferably 12 or more. The chlorine concentration of the fine powder B1F typically becomes, for example, 0.2 mass% to 2 mass%, and more typically 0.3 mass% to 1.5 mass%. On the other hand, the chlorine concentration of the coarse powder B1C is typically reduced to 0.01 mass% to 0.2 mass%, and more typically reduced to 0.02 mass% to 0.1 mass%.

[0064] The chlorine concentration contained in biomass ash B1 (B1C, B1F, etc.) can be measured by well-known methods. For example, after acid decomposition treatment, a method of measuring by potentiometric titration is preferably exemplified.

[0065] The total alkali concentration ratio of fine powder B1F to 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 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 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.

[0066] The total alkali concentration contained in biomass ash B1 (B1C, B1F, etc.) can be measured by well-known methods. For example, a method in accordance with JIS R 5204 "Fluorescent X-ray Analysis Method for Cement" is preferably exemplified.

[0067] The sulfur oxide concentration ratio of fine powder B1F to 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 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 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.

[0068] The sulfur oxide concentration contained in biomass ash B1 (B1C, B1F, etc.) can be measured by well-known methods. For example, a calibration curve method using a fluorescent X-ray apparatus is preferably exemplified.

[0069] 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 even more preferably 3 or more. The calcium oxide concentration of the fine powder B1F typically ranges from 8% to 40% by mass, and more typically from 15% to 35% by mass. On the other hand, the calcium oxide concentration of the coarse powder B1C is typically reduced to 3% to 15% by mass, and more typically to 5% to 10% by mass.

[0070] The calcium oxide concentration contained in the biomass ash B1 (such as B1C, B1F, etc.) can be measured by a well-known method. For example, the calibration curve method using a fluorescent X-ray apparatus is preferably exemplified.

[0071] This classification step S10 corresponds to step (a).

[0072] (Input step S20) The fine powder B1F obtained in the classification step S10 is introduced (added) as a raw material for the cement clinker or as a mixing material to the cement clinker or cement. In the example of FIG. 2, an example is illustrated where the fine powder B1F is mixed with the cement clinker Cn1 obtained from the clinker production facility 10 and, if necessary, gypsum in the grinding facility 30 and subjected to a grinding process to produce a blended cement. At that time, watering or a grinding aid is added as necessary.

[0073] Since the fine powder B1F has a finer particle size than the coarse powder B1C, it exhibits high reactivity. Therefore, it is preferable to recover the fine powder B1F obtained after the classification step S10 and use it as a cement mixing material. Thereby, the pozzolanic reaction is activated and the strength of the cement hardened product is increased.

[0074] As the pulverizing equipment 30, a general mill used in the finishing process such as a tube mill can be used. The mill is also called a finishing pulverizer, 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 pulverized. When using gypsum, the gypsum is not particularly limited, and examples thereof include natural dihydrate gypsum, flue gas desulfurization gypsum, phosphogypsum, titanium gypsum, and fluoro gypsum. These may be used alone or in combination of two or more.

[0075] The fine powder B1F 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. Further, 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.

[0076] As another method, the fine powder B1F obtained in the classification step S10 may be directly charged into the clinker cooler 13. Examples of the charging method include 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. The charging amount is preferably set to be about 0.5% by mass to 20% by mass based on the mass of the cement. If an air quenching cooler is used as the clinker cooler 13, it is suitable because the fine powder B1F can be charged into a predetermined position inside the clinker cooler 13.

[0077] When the fine powder B1F is charged into the clinker cooler 13, it is convenient that 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 fine powder B1F preferably has a moisture content of 50% by mass or less and is preferably charged in a lump or granular form.

[0078] Although not shown in Fig. 2, the recovered fine powder B1F may be mixed with the cement obtained after the cement clinker Cn1 is pulverized in the pulverizing equipment 30. The timing of this mixing may be on the path up to the cement silo where the cement is stored in the latter stage of the pulverizing equipment 30, or it may be inside the cement silo, or further, it may be during the concrete mixing process when using the cement. Since the fine powder B1F exhibits high reactivity, regardless of the timing of mixing the fine powder B1F, the effect of increasing the strength of the cement hardened product can be obtained. However, more precisely speaking, it is more preferable to put the fine powder B1F into the cement clinker Cn1 or the pulverizing equipment 30 than to mix it with the cement obtained after the cement clinker Cn1 is pulverized in the pulverizing equipment 30, because the particle size is finer and the reactivity is higher.

[0079] On the other hand, the coarse powder B1C obtained after the classification step S10 has lower reactivity than the fine powder B1F, and the alkali metal concentration, calcium concentration, chlorine concentration, and sulfur concentration are also reduced compared to the fine powder B1F. Therefore, as shown in Fig. 2, it can be used in the clinker production equipment 10 together with the cement clinker raw material Y1. For example, it can be charged into the mixer for preparing the cement clinker raw material Y1 in the clinker production equipment 10, charged into the preheater 11 and the calciner, charged into the kiln end and the 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 into various cement production stages.

[0080] Also, as described above, the chlorine concentration of the coarse powder B1C is greatly reduced by the classification step S10. Furthermore, since the sulfur content is also greatly reduced, the blockage due to the adhesion of low-melting substances to the preheater, kiln end, and kiln is suppressed. Separately, after pulverizing to increase the reactivity, it may be used as a cement admixture in the same manner as the fine powder B1F.

[0081] This charging step S20 corresponds to step (b).

[0082] [Second Embodiment] The second embodiment of the cement manufacturing method and the cement manufacturing system will be described focusing on the differences from the first embodiment. FIG. 4 is a drawing schematically showing the processing flow of the cement manufacturing method in this embodiment. FIG. 5 is a drawing schematically showing an example of the detailed processing flow of the water washing step S30 described later. FIG. 6 is a block diagram schematically showing the structure of the cement manufacturing system in this embodiment.

[0083] The cement manufacturing system 1 of this embodiment shown in FIG. 6 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. 7.

[0084] (Water washing step S30) The biomass ash B1 is subjected to a water washing treatment by the water washing facility 40. More specifically, as shown in FIG. 5, a step S31 of slurrying the biomass ash B1, a step S32 of washing the slurry, and a step S33 of dehydrating are executed.

[0085] As an example, the water washing facility 40 shown in FIG. 7 includes a powder dissolution tank 43 for adding water W1 to the accommodated biomass ash B1 to form a slurry Lr1 and washing it, a solid-liquid separation device 46 for dehydrating the slurry Lr2 discharged from the powder dissolution tank 43 after water washing, and a conveying device 47 for conveying the dehydrated product Ck1 separated by the solid-liquid separation device 46.

[0086] Furthermore, in the example of the water washing facility 40 shown in FIG. 7, a powder supply device 41 for supplying the biomass ash B1 and a liquid supply device 42 for supplying water W1 are attached to the powder dissolution tank 43. Also, a slurry stirring device 44 equipped with stirring blades is attached for mixing the biomass ash B1 and water W1 and for stirring the slurry Lr1 generated by the mixing.

[0087] 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.

[0088] 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. If 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, if the mass ratio (W1 / B1) is greater than 10, the amount of drainage W3 will increase.

[0089] 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.

[0090] 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 water W1. Also, the temperature condition is preferably 5°C to 50°C, more preferably 25°C to 50°C, from the viewpoint of the cost involved in the treatment, although the higher the temperature, the better the elution efficiency of water-soluble components such as chlorine from the biomass ash B1.

[0091] 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 centrifugal pump, a piston pump, or a mono pump can be used.

[0092] In the solid-liquid separator 46, the slurry Lr2 is separated into solid and liquid to obtain a dehydrated product Ck1 (dehydration step S33). As the solid-liquid separator 46, a typical filtration device such as a filter press, a pressurized leaf filter, a screw press, a belt press, a belt filter, or a sedimentation separator can be used.

[0093] 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 moisture content of the dehydrated product is preferably 20% by mass to 90% by mass, and more preferably 30% by mass to 70% by mass.

[0094] The components dissolved in the liquid phase of the slurry Lr2 are removed into the wastewater W3, so the amount of cement-repellent components such as chlorine in the resulting dehydrated product Ck1 is reduced compared to the raw ash. On the other hand, the heavy metals and other substances contained in the raw ash are also dissolved into the wastewater W3, so it may be discharged into the environment after undergoing appropriate water purification treatment.

[0095] 7, a water washing device 49 may be provided to the solid-liquid separator 46, and water W2 may be added to the dehydrated product Ck1, followed by dehydration again. In this way, most of the liquid phase of the slurry Lr2 is replaced with water, so that the eluted components can be removed more reliably.

[0096] This water washing step S30 corresponds to step (c).

[0097] The dehydrated product Ck1 obtained through the water washing step S30 is in a modified state of biomass ash B1 (modified biomass ash B2), in which the amount of cement-repellent components such as chlorine has been reduced, and the amount of easily reactive calcium oxide and calcium hydroxide that affect the strength development and fluidity of cement has been sufficiently reduced. Therefore, by using this modified biomass ash B2 and carrying out the classification and mixing steps as in the first embodiment, it is easy to maintain the quality of the cement admixture at a uniform level. In particular, by using biomass ash B1 discharged from a fluidized bed combustion furnace into which limestone containing calcium components has been added, the above effect can be significantly achieved.

[0098] Incidentally, 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 a well-known method such as an ion exchange resin, membrane separation, or precipitation formation by silver or lead ions. Thereby, while removing chlorine that causes rebar corrosion, the alkali metals showing an effect of enhancing the 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 a reduced activity due to water washing, the weakness of the reduced activity of the modified biomass ash B2 can be compensated by adding the drainage water W3 after water washing as a cement additive.

[0099] In particular, since the biomass ash B1 has a lower chlorine concentration than the 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 pulverizing equipment 30, more alkali metals can be utilized as a cement additive.

[0100] By introducing the drainage water W3 between the clinker cooler 13 and the pulverizing equipment 30, it can be used as a cement additive while serving as watering for cooling the cement clinker Cn1 and adjusting the temperature in the pulverizing equipment 30 without drying or solidifying. More specific injection locations include the clinker cooler 13 at 400 °C or lower, and subsequent conveyors and pulverizing equipment 30 in the cement manufacturing equipment. If the temperature exceeds 400 °C, it will evaporate instantly and will not be easily contained in the cement. If it is downstream of the pulverizing equipment 30, there is a risk that moisture will remain in the cement and the quality will deteriorate due to weathering and hydration.

[0101] Incidentally, the drainage water W3 may be introduced between the clinker cooler 13 and the pulverizing equipment 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 pulverized cement or concrete kneading, and any amount can be easily added.

[0102] As a means for reducing chloride ions, those using an amphoteric ion exchange resin or a nanofiltration membrane are particularly preferred. According to this, sulfate ions, carbonate ions, and chloride ions can be selectively separated, and water with a high sulfate ion and carbonate ion concentration and a low chloride ion concentration, and water with a low sulfate ion and carbonate ion concentration and a high chloride ion concentration can be obtained.

[0103] The wastewater W3 obtained after washing the biomass ash B1 often contains selenium and hexavalent chromium. By using the above amphoteric ion exchange resin or nanofiltration membrane, selenium and hexavalent chromium, which exhibit the same form as sulfate ions, are separated to the water side 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. Also, 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 pulverizing equipment 30, more alkali metals can be utilized as a cement additive with the same amount of water sprayed.

[0104] As described above, since the wastewater W3 (cement additive) obtained from the washing water and the washed modified biomass ash B2 can be used simultaneously as a cement admixture, the biomass ash B1 can be utilized without any waste. Thereby, an effect of reducing the amount of wastewater to be disposed of and the load of its wastewater treatment can also be expected.

[0105] 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. 8A and 8B). 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.

[0106] FIG. 8A 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. 8B is a drawing schematically showing the structure of the water washing facility 40 in this case according to FIG. 7. Note that in FIG. 8B, the gas supply device 51 and the flotation device 53 are also shown together with the water washing facility 40.

[0107] (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.

[0108] By adjusting the pH during water washing to the acidic side, chlorine contained in the biomass ash B1 can be more efficiently dissolved in water compared to the case where the pH is not adjusted. In addition, the calcium component contained in the biomass ash B1 is easily stabilized in 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 little quality variation.

[0109] 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.

[0110] The pH adjuster is not particularly limited as long as it can adjust the pH of the slurry Lr1 to the acidic side. For example, acid solutions such as sulfuric acid and CO2-containing gases can be mentioned. 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 more easily carbonated and stabilized in the form of calcium carbonate.

[0111] In FIG. 8B, as an example, a case is illustrated where the CO2-containing gas G1 is supplied from the gas supply device 51 to the slurry Lr1 in the powder dissolution tank 43. 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.

[0112] 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, 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.

[0113] 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 the spot 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 the spot, 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.

[0114] 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 the 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.

[0115] 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 grinding aids when grinding cement clinker Cn1 in the grinding equipment 30. Amines have an amino group and a hydroxyl group in the molecule. In particular, examples of amines used as grinding aids 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 have functionality as a grinding aid in subsequent processes, making it suitable as a cement admixture.

[0116] It should be noted that it is also 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 is useful for drying the moisture contained in the dehydrated product Ck1.

[0117] As the gas blowing means (gas supply device 51), it is only necessary 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, it is also possible to blow the combustion exhaust gas of the cement kiln 12, the combustion exhaust gas of the biomass incineration facility or the biomass power plant into the dehydrated product Ck1.

[0118] This oxidation step S41 corresponds to step (d).

[0119] (Unburned carbon removal step S42) The unburned carbon removal step S42 is a step for removing unburned carbon contained in the biomass ash B1. Since a large amount of unburned carbon is contained in the biomass ash B1, 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 a blending material, it may cause the concrete to turn black or the fluidity to decrease.

[0120] Specifically, when the water washing step S30 is executed, a method can be adopted in which a treatment such as stirring is performed while adding an unburned carbon removing agent D1 such as oil or a surfactant from the unburned carbon removing agent supply device 52 into the powder dissolution tank 43. The obtained slurry Lr2a is subjected to a flotation separation treatment 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.

[0121] As a result, the water washing step S30 and the unburned carbon removal step S42 are performed in parallel and continuously.

[0122] This unburned carbon removal step S42 corresponds to step (e).

[0123] (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 a coarse powder B2C and a fine powder B2F.

[0124] Note that the water washing step S30 and the classification step S10 may be performed simultaneously. Specifically, methods such as a sieve, a liquid cyclone, and centrifugation can be mentioned.

[0125] The activity index of the fine powder B2F obtained through the water washing step S30 and the classification step 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.

[0126] The chlorine concentration of this fine powder B2F is reduced, for example, typically to 0.01% to 0.2% by mass, more typically to 0.02% to 0.1% by mass.

[0127] The total alkali metal concentration of this fine powder B2F is reduced, for example, typically to 1% to 8% by mass, more typically to 3% to 6% by mass.

[0128] The sulfur oxide concentration of this fine powder B2F is reduced, for example, typically to 0.5% to 4% by mass, more typically to 1% to 3% by mass.

[0129] 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, more typically to 0.005 mg / L to 0.01 mg / L.

[0130] 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, more typically to 0.02 mg / L to 0.05 mg / L.

[0131] The elution amounts of the above-mentioned selenium (Se) and hexavalent chromium (Cr 6+ ) can be measured by well-known methods. As a preferred 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 Appearance", for selenium (Se), it is measured by ICP mass spectrometry, and for hexavalent chromium (Cr 6+ ), it is measured by diphenylcarbazide absorption photometry.

[0132] Also, as shown in the examples described later, the content of easily reactive calcium oxide and calcium hydroxide that affect 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, and quality fluctuations can be suppressed.

[0133] For example, the calcium hydroxide content of 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.

[0134] Also, for example, the calcium sulfate (gypsum) content of 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.

[0135] The above-described 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.

[0136] Also, the above-described calcium hydroxide content can be measured by a well-known method. For example, a method of obtaining by measuring the heat of dehydration near 400 °C by DSC (differential scanning calorimeter) is preferably exemplified.

[0137] Also, the above-described calcium sulfate (gypsum) content 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.

[0138] (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 fine powder B1F obtained through the water washing step S30 in the first embodiment may be replaced with the fine powder B2F obtained through the water washing step S30, and the coarse powder B1C obtained through the water washing step S30 may be replaced with the coarse powder B2C.

[0139] In particular, in this embodiment, since the water washing step S30 is executed before the feeding 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 used for temperature control in the grinding equipment 30 for preventing the alteration of gypsum and the like. If the moisture contained in the fine powder B2F is excessive, it can be simply dehydrated by sedimentation separation or the like. Conversely, if the moisture is insufficient, an appropriate amount may be sprayed onto the grinding equipment 30.

[0140] Similar to what was described above in the first embodiment, the fine powder B2F obtained after classification can also be directly fed into the clinker cooler 13. The temperature inside the clinker cooler 13 is usually 200 to 1200 °C, and the heating temperature can be selected according to the feeding 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 feed it into the low-temperature part of 200 °C to 800 °C inside 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.

[0141] In addition, although the alkali metal content of the modified biomass ash B2 obtained by the method of this embodiment is reduced by performing 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 concrete, there is a possibility of causing an alkali-aggregate reaction depending on the aggregate.

[0142] Therefore, in order to reduce the possibility of alkali-aggregate reaction, it is also possible to add (add) latent hydraulic substances such as blast furnace slag, pozzolanic substances such as fly ash, volcanic ash, volcanic rock, and calcined clay together with the modified biomass ash B2. Note that the addition (addition) of such latent hydraulic substances and pozzolanic substances is also applicable when using the fine powder B1F in the case where the water washing step S30 is not performed as in the first embodiment.

[0143] [Third Embodiment] Regarding the third embodiment of the cement manufacturing method and the cement manufacturing system, the description will focus on the differences from the first and second embodiments. FIG. 9 is a drawing schematically showing the processing flow of the cement manufacturing method in this embodiment. FIG. 10 is a block diagram schematically showing the structure of the cement manufacturing system in this embodiment.

[0144] In this embodiment, compared with the second embodiment, the only difference is that the water washing step S30 is performed after the classification step S10, and the rest is the same as the second embodiment. In this embodiment, the water washing step S30 is performed only on the fine powder B1F classified by the classification step S10.

[0145] 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 this 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 the implementation of the water washing step S30.

[0146] In this embodiment as well, similar to the second embodiment, the oxidation step S41 and the unburned carbon removal step S42 may be executed. Since the rest is the same as the above-described embodiments, the description is omitted.

[0147] [Alternative Embodiment] Hereinafter, an alternative embodiment will be described.

[0148] 〈1〉 As shown in FIG. 11, among the coarse powder B1C and the fine powder B1F obtained by classifying the biomass ash B1 in the classification equipment 20, the coarse powder B1C may be washed by the water washing equipment 40. The content concentrations of chlorine and sulfur in the coarse powder B1C are reduced by the classification step S10, and further reduced by the water washing step S30. Therefore, it can be utilized as a raw material for the cement clinker Cn1.

[0149] In this case, since the drainage W3 obtained in the water washing step S30 is obtained after washing the coarse powder B1C with little chlorine originally, the content chlorine concentration is in a low state. Therefore, the drainage W3 may be mixed with the cement clinker Cn1 without taking measures to reduce the contained chlorine ions as described in the second embodiment.

[0150] On the other hand, for the fine powder B1F, after separately performing a water washing process as needed, it may be mixed with the cement clinker Cn1 or cement.

[0151] 〈2〉 As shown in Fig. 12, for the fine powder B1F obtained by classifying the biomass ash B1 in the classification equipment 20, after being washed with water by the water washing equipment 40, the obtained modified biomass ash B2F may be used as a raw material for the cement clinker Cn1. Specifically, it includes feeding into the raw material preparation system equipment such as a mixer or crusher for preparing the raw materials of the cement clinker, feeding into the preheater top or calciner before the cement kiln, feeding into the cement kiln kiln end, and feeding into the high-temperature part in front of the cement kiln (rotary kiln). Although the fine powder B1F contains chlorine and sulfur at a higher concentration compared to the coarse powder B1C, the content concentration of chlorine and sulfur contained in the biomass ash B1 is reduced by being washed with water, so it can be utilized as a raw material for the cement clinker Cn1.

[0152] Thereby, compared with the case without water washing, blockage due to adhesion of low melting point substances to the preheater, kiln end, and kiln is suppressed, 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 used as a cement admixture, or when potential 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.

[0153] On the other hand, for the coarse powder B1C obtained in the classification step S10, since the chlorine content ratio can be reduced compared to the biomass ash B1, it can be used as an admixture for the cement clinker Cn1 or cement. Fig. 12 illustrates the case where the coarse powder B1C is mixed after being pulverized by the pulverizing equipment 30.

[0154] <3>In the above third embodiment (see FIGS. 9 and 10), the fine powder (modified biomass) B2F after washing obtained through the classification step S10 and the washing step S30 may also be used in the clinker production facility 10 as a raw material for the cement clinker Cn1, just like the coarse powder B1C (see FIG. 13).

[0155] <4>In each of the above embodiments, the process until cement is produced by grinding the cement clinker Cn1 in the grinding facility 30 has been described. However, as the charging step S20, the fine powders (B1F, B2F) of the biomass ash obtained in each embodiment may be charged and kneaded with cement and water, and used in a method for producing a cement hardened product such as concrete or mortar.

Example

[0156] [Example 1] Incineration fly ash BA-1 (particle size D 50 (frequency) is 47.2 μm, and the ignition loss (ig.loss) at 975 °C is 4.17%) was obtained from the biomass power generation facility P1 that uses palm coconut shells as fuel and conducts power generation using a circulating fluidized bed furnace, and the influence on the component composition of the 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·BEL) is as shown in FIG. 3.

[0157] 《Test method》 The test method will be described below.

[0158] 〈1. Classification〉 Using a sieve with an aperture size set to the classification points 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, while coarse powder B1C was obtained as the residue on the sieve. This process corresponds to the classification step S10. The classification points were 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".

[0159] The particle size distribution of the biomass ash after classification is as shown in Table 1. Table 1 also shows 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 at a classification point of 45 μm. The particle size distribution was measured by a laser diffraction particle size distribution analyzer (MT3300EX II manufactured by Microtrac Bell).

[0160]

Table 1

[0161] 〈2. Chemical composition analysis〉 For raw ash B1 (#1) derived from incineration fly ash BA-1, each coarse powder B1C (#2, #4), and each fine powder B1F (#3, #5), raw ash B1 wet-ashed by the following method (#1W), and coarse powder B1C (#2W) obtained by classifying wet-ashed raw ash B1 (#1W) at 45 μm, the chemical components were measured. Also, coarse powder B1C (#9) and fine powder B1F (#10) obtained by classifying raw ash B1 at a classification point of 20 μm were obtained, and the chemical components were measured in the same way for these. Furthermore, for raw ash B1 (#1) and fine powder B1F (#3) classified at 45 μm, samples prepared by subjecting them to a water washing treatment by the following method (#1Wp, #3Wp) were prepared, and the chemical components were measured in the same way.

[0162] The method of wet ashing is as follows. To the raw ash B1 (reference #1), 20% by mass of water (16.7% by mass of water content) was added by external division, and then it was 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 "reference #1W", and the coarse powder B1C obtained by classifying this wet-ashed raw ash #1W corresponds to "reference #2W". When classifying the wet-ashed raw ash B1 (#1W), an air jet sieve (manufactured by Hosokawa Micron Corporation, e200LS) was used.

[0163] 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 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.

[0164] Also, the obtained coarse powder was pulverized using a ball mill.

[0165] 《Analysis》 The measurement of chemical components was carried out 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 (manufactured by Rigaku Corporation, ZSX Primus II). The results are shown in Table 2. In addition, the loss on ignition of each was measured by a method in accordance with JIS R 5202 "Chemical Analysis Method of Cement".

[0166] In addition, the amount of calcium carbonate in the incineration fly ash and the obtained sample was determined by finding the mass reduction amount near 600°C to 700°C when heating approximately 50 mg of the sample at a heating rate of 20°C / min to 1000°C in a nitrogen atmosphere, and calculating the ratio with the weight reduction with the reagent (using TG-DTA 2000SR manufactured by NETZSCH). As a result, the amount of calcium carbonate in the original ash B1 was 5.5%, and that of the wet-ashed sample (#1W) was 5.6%. The amount of hydrate formed was obtained by subtracting the decarbonation component volatilized from the amount of calcium carbonate from the above-mentioned ignition loss. As a result, the amount of hydrate formed in the original ash B1 was 1.8%, and that of the wet-ashed sample (#1W) was 6.0%.

[0167]

Table 2

[0168] According to Table 2, when classifying the original ash B1, which is dry ash, with the point between the peak on the fine particle side and the peak on the coarse particle side when the particle size distribution is represented by frequency as the classification point, most of the chlorine component and sulfur component (SO3) were contained on the side of the fine powder (B1F). Also, it was confirmed that the chlorine component could be efficiently removed by washing this (B2F) with water. Therefore, it can be seen that especially the fine powder after washing is suitable as a cement admixture.

[0169] On the other hand, although the reduction amount of alkali metals on the side of the coarse powder (B1C) obtained by classifying the original ash is small, it contains almost no chlorine component and sulfur component, and compared with the original ash, CaO has decreased and SiO2 has increased. Therefore, it can be seen that the coarse powder is close to the chemical composition of coal ash and is suitable as a raw material for cement clinker.

[0170] Also, when comparing the wet-ashed original ash B1 (#1W) with the coarse powder B1C (#2W) obtained by classifying it at 45 μm, it is confirmed that the degree of decrease in chlorine concentration due to classification is low. This is presumably because agglomeration and hydration reactions occurred due to the wet-ashing of the original ash B1, and chlorine (Cl) components were incorporated into the generated hydrates, resulting in a decrease in the removal rate by classification. The wet-ashed original ash B1 (#1W) had a hydration reaction, and the loss on ignition was increased compared to the original ash B1 which is dry ash.

[0171] 〈3. Physical Tests〉 For the original ash B1 (#1) derived from the incineration fly ash BA-1, the coarse powder B1C (#2) and the fine powder B1F (#3) obtained with a classification point of 45 μm, the Blaine specific surface area, the flow value ratio, and the activity index were measured by a method conforming to Appendix C of JIS A 6201 "Fly Ash for Concrete". Furthermore, the coarse powder B1C (#2) was ground with a mill to have a particle size comparable to that of the fine powder B1F, and the Blaine specific surface area, the flow value ratio, and the activity index were similarly measured. Note that the ground material (#2C) obtained by grinding the coarse powder B1C is, for example, in Fig. 12, a simulation of the material obtained by grinding the classified coarse powder B1C with the grinding equipment 30 (conveniently referred to by the symbol "B1Cp"). The measurement results are shown in Table 3.

[0172]

Table 3

[0173] According to Table 3, when the fine powder B1F obtained by classifying the original ash B1 was used as a admixture, it was confirmed that the activity index was higher than that of the original ash B1. Note that the coarse powder B1C does not contain chlorine, and it became clear that if it is ground until the Blaine specific surface area becomes 4000 cm 2 / g or more (B1Cp), it can be used as a pozzolanic admixture with higher reactivity than the original ash.

[0174] [Example 2] Fly ash (particle size D from the biomass power generation facility P2 that uses woody biomass (thinned wood) as fuel and conducts power generation by a circulating fluidized bed furnace50 Obtained a (frequency) of 45.3 μm and a loss on ignition (ig.loss) of 2.3% at 750 °C, washed this, and examined the influence of the presence or absence of an oxidation process (particularly a carbonation process) during this washing on the component composition.

[0175] 《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 form a slurry, and stirred at 400 rpm for 30 minutes with a stirrer. At this time, when adjusting the pH by flowing in CO2 gas during 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. After adding 400 g of tap water to the cake on the obtained filter paper to wash the slurry, it was recovered. (Procedure 3) The recovered cake was naturally dried, its mass was measured, and various analyses were performed.

[0176] Table 4 below shows the levels of each washing condition.

[0177]

Table 4

[0178] 《Analysis》 The obtained samples were analyzed by the following methods respectively. Quantification of Cl: After decomposing the sample with nitric acid, it was measured by potentiometric titration. Quantification of K and Na: After decomposing the sample with acid, it was measured by ICP emission spectrometry. Se, Cr 6+ Elution test: After preparing a test solution by a method compliant with JIS K 0058-1 "Test method for chemical substances in slags - Part 1: Elution test method 5. Test by the form of use", 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: Samples subjected to a drying treatment at 40°C were measured using a fluorescent X-ray apparatus (FP method: Fundamental Parameter method). The measurement results are shown in Tables 5 and 6.

[0179]

Table 5

[0180]

Table 6

[0181] According to Table 5, by washing the raw ash with water, most of the chlorine is effectively removed. When used as a blending material, after the cement is water-hardened, it is confirmed that it meets the acceptance criteria of 0.035 mass% or less, indicating that there is no risk of corrosion to steel bars and the like. That is, when the biomass ash after washing is classified, it can be seen that almost no chlorine is contained in both the fine powder side and the coarse powder side.

[0182] Also, according to Table 5, the water-soluble selenium and hexavalent chromium contained in the raw ash are also effectively removed by washing with water, and it is clarified that the risk of elution of heavy metals when used as a blending material is reduced.

[0183] 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.

[0184] According to the results of Level 2-2, it was clarified that by performing water washing while blowing CO2 gas, the CO2 content of the biomass ash after washing increases. Therefore, at least a part of the components for pH adjustment is considered to be immobilized in the ash and calcium carbonate is generated after the water washing operation. Also, by performing water washing while blowing CO2 gas, calcium hydroxide has disappeared. In Table 6, the calcium hydroxide content being less than 0.01% means that it is below the detection limit.

[0185] Table 7 below shows the results of examining the forms of calcium components in ash by the XRD method (X-ray diffraction method).

[0186]

Table 7

[0187] According to Table 6 and Table 7, in the raw ash, the presence of each Ca compound such as CaO (quicklime), Ca(OH)2 (slaked lime), CaCO3 (limestone), and CaSO4 (gypsum) was confirmed as the form of calcium components. In contrast, at 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, at Level 2-2 where water washing was performed under the condition of pH 9 while blowing CO2 gas, it was confirmed that the presence of CaO (quicklime) and Ca(OH)2 (slaked lime) disappeared.

[0188] [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 wood pellets and palm coconut shells as fuel in a stoker furnace, and the same test as in Example 2 was conducted. The results are shown in Table 8 and Table 9. Note that at Level 3-2, sulfuric acid for pH adjustment is added during water washing.

[0189]

Table 8

[0190]

Table 9

[0191] According to Table 8, by washing the raw ash with water, almost all chlorine is effectively removed, and after the cement used as a blending material is water-cured, it is confirmed that the allowable standard of less than 0.035% by mass, which indicates 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.

[0192] Also, according to Table 8, 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 a blending material is reduced.

[0193] 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 pozzolanic blending material. Furthermore, it has been clarified that the SO3 content rate increases by adding sulfuric acid and performing washing with water. Therefore, it is considered that at least a part of the sulfuric acid component for pH adjustment is immobilized in the ash after the washing operation.

Explanation of symbols

[0194] 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: 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: Conveying device 49: Washing and cleaning device 51: Gas supply device 52: Unburned carbon removal agent supply device 53: Floatation 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 Removing Agent G1: CO₂-Containing Gas Lr1: Slurry Lr2(Lr2a,Lr2b): Slurry W1,W2: Water W3: Drainage Water Y1: Cement Clinker Raw Material

Claims

1. a step (a) of classifying biomass ash into coarse powder and fine powder with a classification point of 20 μm or more and 100 μm or less; a step (b) of introducing the fine powder obtained in the step (a) into at least one of a cement clinker raw material fed into a cement kiln, a cement clinker obtained from the cement kiln, or cement after pulverization treatment of the cement clinker; a step (c) of washing the biomass ash with water; A cement manufacturing method, wherein the step (b) is a step of introducing the fine powder after being washed with water by the step (c).

2. The cement manufacturing method according to claim 1, wherein the step (c) is a step of washing only the fine powder obtained in the step (a) with water.

3. The cement manufacturing method according to claim 1 or 2, further comprising a step (d) of oxidizing the biomass ash during or after the execution of the step (c).

4. The cement manufacturing method according to any one of claims 1 to 3, further comprising a step (e) of removing unburned carbon contained in the biomass ash during the execution of the step (c).

5. The cement manufacturing method according to any one of claims 1 to 4, wherein the step (b) is a step of introducing the fine powder into at least one of a cement clinker obtained from the cement kiln or cement after pulverization treatment of the cement clinker.

6. The cement manufacturing method according to any one of claims 1 to 4, wherein the step (b) is a step of introducing the fine powder into a cement clinker raw material fed into the cement kiln.

7. The cement manufacturing method according to any one of claims 1 to 6, wherein the step (b) is a step of introducing at least one of latent hydraulic substances and pozzolan in addition to the fine powder.

8. The cement manufacturing 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. a classification facility for classifying biomass ash into coarse powder and fine powder with a classification point of 20 μm or more and 100 μm or less; a cement kiln for firing a cement clinker raw material to produce a cement clinker; A grinding facility that grinds the cement clinker obtained from the cement kiln to produce cement, and a water washing facility that washes the biomass ash, wherein the fine powder after being washed by the water washing facility 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 grinding facility. A cement manufacturing system characterized by this.

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