JPWO2013114719A1 - Method for producing cement composition - Google Patents

Abstract

  The present invention provides a method for producing a cement composition capable of using a large amount of coal ash having a high carbon content and reducing fuel costs. Specifically, the method for producing a cement composition of the present invention includes a cement clinker firing step of firing cement clinker having a cement mineral composition calculated using the Borg formula within a specific range, and 100 parts by mass of the cement clinker. On the other hand, a molded product obtained by molding a composition containing coal ash, a binder, and water is put into a region of 800 to 1400 ° C. in a cooler at a ratio of 0.2 to 100.0 parts by mass, and cement. In addition to mixing with clinker, removing carbon and the like contained in the coal ash in the molded product by burning and removing it, and the mixture (a) of the cement clinker and the molded product, or the mixture (a) And a mixture crushing step of crushing the mixture (b) to which gypsum is added.

Description

  The present invention relates to a method for producing a cement composition capable of using a large amount of coal ash having a high carbon content.

According to the Coal Energy Center, the amount of coal ash generated in 2009 was 10.95 million tons, of which 89.93 million tons, accounting for 73% of the total. Most of this is coal ash generated at coal-fired power plants. And conventionally, the content rate of unburned carbon in this coal ash was only about several mass%.
However, due to diversification of coal brands, strengthening of environmental measures such as NOx regulations, and priority on power generation efficiency in the summer when power demand increases, coal ash is recovered without completely burning pulverized coal at thermal power stations. Increasing cases. Therefore, at present, the carbon content in coal ash and its fluctuation range are expanded to about 3 to 30% by mass.

If coal ash with a large carbon content and its fluctuation range is used as a concrete admixture, unburned carbon will float on the surface of the concrete and the appearance of the concrete will be impaired, and AE agent will be adsorbed and fine air will not be entrained in the concrete. It becomes difficult to control the quality of concrete. Moreover, since the ignition loss of the fly ash for concrete prescribed | regulated to JISA6201 is prescribed | regulated as 8% or less, the said coal ash is not suitable as an admixture also in this point.
However, the amount of coal ash generated in the electric power business has increased from 5.76 million tons in 1999 to about 1.5 times over the past 10 years, and thermal power plants will continue to operate in the future to supplement nuclear power generation. As coal ash is expected to increase, there is a need for a method that can effectively utilize coal ash with a large amount of unburned carbon without being discarded.

Under such circumstances, methods for utilizing coal ash with a large amount of unburned carbon in cement production have been proposed.
For example, in Patent Document 1, coal ash is put on a cement clinker (hereinafter referred to as “clinker”) in a cooler, and unburned carbon in the coal ash is burned and removed, and then the coal ash is combined with the clinker. A method for producing a cement to be crushed has been proposed. And in this method, it is said that it is preferable to put the coal ash into the cooler after performing heavy processing by mixing with liquid or pressure molding so that the coal ash is not scattered in the cooler. (See paragraph 0016).

  However, even if the coal ash does not scatter until the molded product falls to the cooler, the cohesive force of the molded product is weak in mixing with liquid or molding only by pressure, and therefore easily collapses due to the impact of dropping. The coal ash that has collapsed and becomes finer easily reacts with the clinker, and the cement mineral composition in the clinker varies depending on the degree of the reaction, making it difficult to maintain the clinker quality constant. On the other hand, if the strength of the molded product is too high, pulverization in the subsequent process becomes difficult and the pulverization efficiency decreases, and if the pulverization properties of the molded product and clinker are different, the cement particle size distribution is excessively expanded. May adversely affect the quality of the product.

  Therefore, there is a demand for a method for producing a cement composition that can use a large amount of coal ash having a high carbon content and that can reduce the production cost (raw material cost, fuel cost, etc.) of the clinker, particularly the fuel cost.

JP 2005-104792 A

  Therefore, an object of this invention is to provide the manufacturing method of the cement composition which can reduce the mass use of coal ash with a high carbon content rate, and the manufacturing cost of a clinker, especially fuel cost.

Then, when the present inventors examined the manufacturing method of the cement composition which meets the said objective,
(I) When a coal ash molding formed using a specific binder or the like is introduced into a clinker having a specific cement mineral composition in a specific temperature range of the cooler, the clinker does not react with the coal ash, and the clinker And a mixture of unburnt carbon burned and reduced coal ash, and
(Ii) It is possible to easily produce a cement composition having a stable quality by simply crushing the mixture or mixing gypsum with the mixture and crushing.
(Iii) According to the production method, coal ash having a high carbon content can be used in a large amount, and the production cost of clinker, particularly the fuel cost can be reduced.
And the present invention was completed.

That is, this invention is a manufacturing method of the cement composition which has the following structures. Hereinafter, “%” means “% by mass” unless otherwise specified.
[1] A method for producing a cement composition including the following steps (A) to (C).
Cement mineral composition calculated using (A) Borg formula, 20-80% by _{C 3} S, 5 to 60% for _{C 2} S, 1 to 16% in the _{C 3} A, and at _C 4 AF 6 to 16 The clinker firing step (B) for firing the clinker that is% is 0.2 to 100.0 parts by mass of a molded product obtained by molding a composition containing coal ash, a binder, and water with respect to 100 parts by mass of the clinker. In a ratio, the carbon and the organic matter contained in the molded product are removed by burning and removing carbon and organic substances contained in the molded product while being mixed with the clinker by being charged into the 800-1400 ° C. region of the cooler. Mixture crushing step of crushing mixture (a) of product or mixture (b) obtained by adding gypsum to mixture (a)

[2] The binder is starch, polyvinyl alcohol, cellulose derivative, polyalkylene oxide, polycarboxylic acid, polyvinyl pyrrolidone, polyvinyl acetate, polyurethane, ethylene / vinyl acetate resin, styrene / butadiene rubber, natural rubber, agar, and The method for producing a cement composition according to [1], wherein the cement composition is one or more organic binders selected from gelatin.
[3] One or more inorganic materials selected from the group consisting of cement, gypsum powder, pozzolanic powder, silica powder, limestone powder, cement kiln dust, expansion material, construction generated soil powder, incinerated ash, slag powder, and clay powder. The method for producing a cement composition according to the above [1], wherein the inorganic binder has a Blaine specific surface area of 2000 to 10000 cm ² / g.
[4] In the step (C), blast furnace slag grains, blast furnace slag powder, fly ash, coal ash, silica powder, limestone, limestone powder, and cement kiln are further added to the mixture (a) or the mixture (b). The manufacturing method of the cement composition in any one of said [1]-[3] which grind | pulverizes the mixture (c) formed by adding 1 or more types chosen from dust.
[5] The method for producing a cement composition according to any one of [1] to [4], wherein the carbon content of the coal ash is 3% or more.

  The method for producing a cement composition of the present invention can use a large amount of coal ash having a high carbon content, and can reduce the production cost of clinker, particularly the fuel cost.

It is a figure for demonstrating the measuring method of the crushing strength of a molded object. It is a schematic diagram which shows an example of the cement manufacturing apparatus for enforcing the manufacturing method of the cement composition of this invention.

As described above, the method for producing a cement composition of the present invention includes (A) a clinker firing step, (B) a carbon removal step, and (C) a mixture pulverization step as an essential step. (D) The raw material preparation step is included before the step (A).
Hereinafter, the present invention will be described by dividing it into a method for producing a cement composition and a molded product.

1. Manufacturing method of cement composition The manufacturing method will be described in detail by dividing it into the steps (A) to (D).
(A) clinker burning step the process, cement mineral composition calculated using the Borg type, 20-80% by _{C 3} S, 5 to 60% for _{C 2} S, 1 to 16% in the _{C 3} A, and It is a step of firing a clinker that is 6 to 16% in C ₄ AF. Examples of clinker having a cement mineral composition within the above range include Portland cement clinker such as ordinary Portland cement clinker and early-strength Portland cement clinker, and eco-cement clinker.
The firing temperature in this step is preferably 1000 to 1450 ° C, more preferably 1200 to 1400 ° C. If this value is 1000-1450 degreeC, there exists a tendency for a cement mineral with high hydraulic property to produce | generate.
Moreover, the baking time in this process becomes like this. Preferably it is 30 to 120 minutes, More preferably, it is 40 to 60 minutes. When the value is less than 30 minutes, firing is not sufficient, and when it exceeds 120 minutes, the production efficiency is lowered.

In addition, if waste is used as part of the raw material, heavy metals may be mixed in the clinker. If the heavy metal content in the clinker exceeds the specified value, the high metal volatilization method, the chloride volatilization method, the chlorine bypass method, or the reduction firing method is used in the clinker firing step to keep the heavy metal content below the specified value. Can be reduced.
Here, the high temperature volatilization method is a method in which a mixed raw material is baked at a high temperature to volatilize and remove heavy metals having a low boiling point contained in the mixed raw material.
The chlorination volatilization method is a method in which heavy metals contained in a mixed raw material are volatilized and removed in the form of chlorides having a low boiling point. Specifically, in the method, when preparing a mixed raw material, a chlorine source such as calcium chloride is mixed, the mixed raw material is baked using a baking furnace, and the generated heavy metal chloride is volatilized and removed. Is the method. When the raw material itself contains enough chlorine for the heavy metal to volatilize, the chlorine source need not be mixed.

The chlorine bypass method is a method utilizing the property that a chlorine source and an alkali source contained in a mixed raw material are volatilized and concentrated in a high-temperature firing furnace. Specifically, in this method, a part of the combustion gas contained in a state where chlorine in the mixed raw material is volatilized is extracted from the flow path of the exhaust gas of the firing furnace, cooled, and generated dust containing chlorine and heavy metals. This is a method of separating and removing the. When the chlorine source or the alkali source is insufficient, it may be adjusted by adding a chlorine source or an alkali source from the outside.
The reduction firing method is a method in which heavy metals in a mixed raw material are reduced and volatilized and removed in the form of a metal having a low boiling point. Specifically, in the method, a mixed raw material containing heavy metal is baked in a reducing atmosphere and / or a reducing agent is added and baked using a baking furnace to reduce the heavy metal, and the reduced heavy metal is volatilized. It is a method to remove.

In addition, the content rate (composition) of the C ₃ S, C ₂ S, C ₃ A, and C ₄ AF is calculated using the following Borg formulas (1) to (4).
C ₃ S (%) = 4.07 × CaO (%) − 7.60 × SiO ₂ (%) − 6.72 × Al ₂ O ₃ (%) − 1.43 × Fe ₂ O ₃ (%) − 2.85 × SO ₃ (%) (1)
C ₂ S (%) = 2.87 × SiO ₂ (%) − 0.754 × C ₃ S (%) (2)
C ₃ A (%) = 2.65 × Al ₂ O ₃ (%) − 1.69 × Fe ₂ O ₃ (%) (3)
C ₄ AF (%) = 3.04 × Fe ₂ O ₃ (%) (4)
However, the chemical formula in the formula represents the content of the compound represented by the chemical formula in the raw material or in the clinker.

(B) Carbon etc. removal process This process is a ratio of 0.2 to 100.0 parts by mass of a molded product obtained by molding a composition containing coal ash, a binder, and water with respect to 100 parts by mass of the clinker. In this step, the mixture is introduced into the region of 800 to 1400 ° C. in the cooler and mixed with the clinker, and the carbon and organic matter contained in the molded product are burned and removed. Note that carbon in the coal ash and organic matter of the binder also serve as a heat energy supply source in the process.
When the amount of the molded product used (input amount) is less than 0.2 parts by mass, the amount of coal ash used is small and fuel cost reduction is insufficient. When the value exceeds 100.0 parts by mass, the cement composition In some cases, the strength development of the resin may decrease. The value is preferably 1 to 80 parts by mass, more preferably 2 to 60 parts by mass with respect to 100 parts by mass of the clinker.

Further, when the temperature of the region charged in the cooler is less than 800 ° C., carbon and organic matter in the molded product may remain without being burned. When the value exceeds 1400 ° C., the clinker reacts with coal ash in the molded product. This may change the cement mineral composition of the clinker. The value is preferably 1100 to 1400 ° C.
In the present invention, in order to maintain the air entrainment action of the AE agent, the carbon content in the molded article after the carbon removal process is preferably 5% or less, more preferably 4% or less, and still more preferably. It is 3% or less, particularly preferably 2% or less.
In addition, since the cooling rate of the clinker is higher than that in the case where the clinker is simply cooled by a cooler due to heat exchange between the clinker and the molded product in the step, the present invention also has an effect of improving the hydraulic property of the clinker.

(C) Mixture crushing step This step is a step of crushing the mixture (a) of the clinker and the molded product or the mixture (b) in which gypsum is further added to the mixture (a) after the carbon removal step. From the viewpoint of effective utilization of resources, the blast furnace slag grains, blast furnace slag powder, fly ash, coal ash, silica powder, limestone, limestone powder, and cement kiln are further added to the mixture (a) or the mixture (b). You may grind | pulverize the mixture (c) formed by adding 1 or more types chosen from dust. However, when the pulverizability of each component in the mixture is greatly different, in order to suppress excessive expansion of the particle size distribution, after mixing and pulverizing components having similar pulverization properties, It may be mixed into a cement composition.
The cement kiln dust is dust contained in the combustion gas discharged from the cement kiln when the clinker is manufactured. In the present invention, cement kiln dust includes chlorine bypass dust. Chlorine bypass dust refers to dust recovered from the combustion gas by a chlorine bypass device attached to a cement kiln, and includes K ₂ O, Cl, SiO _{2 and the} like.

The type of gypsum is not particularly limited, and for example, at least one or more selected from natural dihydrate gypsum, flue gas desulfurization gypsum, phosphate gypsum, titanium gypsum, hydrofluoric gypsum, refined gypsum, hemihydrate gypsum, and anhydrous gypsum. Is mentioned.
The amount of gypsum added is preferably 1.5 to 4.0 parts by mass, more preferably 2.0 to 3.5 parts by mass, and still more preferably 2 in terms of SO ₃ with respect to 100 parts by mass of the mixture (a). .5 to 3.0 parts by mass. When the value is in the range of 1.5 to 4.0 parts by mass, the cement composition has high strength and high fluidity.
Moreover, the brane specific surface area of the gypsum in a cement composition becomes like this. Preferably it is 2000-10000 cm < ² > / g, More preferably, it is 3000-8000 cm < ² > / g. If the value is out of the range of 2000 to 10000 cm ² / g, strength development may be reduced or heat of hydration may be increased.

In the pulverization in the step (C), the mixture may be pulverized as it is, but is preferably pulverized by adding a pulverization aid in order to increase the pulverization efficiency. Examples of the grinding aid include diethylene glycol, triethanolamine, and triisopropanolamine. Among these, triisopropanolamine is more preferable because strength development of the cement composition is improved. The addition ratio of these grinding aids is preferably 0.01 to 1 part by mass with respect to 100 parts by mass of the mixture. As the pulverizer, a ball mill, a rod mill, or the like can be used.
Fineness of the cement compositions produced according to the present invention, strength development, workability, and in view of cost, preferably by Blaine specific surface area 2000~5000cm ² / g, more preferably 2500~4700cm ² / g More preferably, it is 3000-4000 cm < ² > / g.

Further, at least one selected from blast furnace slag powder, fly ash, coal ash, silica powder, limestone powder, and cement kiln dust is added to the pulverized cement composition as long as the physical properties of the cement composition are not impaired. May be.
The method for producing a cement composition of the present invention including the above steps can be used in large quantities even for coal ash having a high carbon content, and as described below, the production cost of clinker, particularly the fuel cost, can be significantly reduced. .
In addition, the cement composition produced according to the present invention does not react with clinker and coal ash in the carbon removal process, so the quality of the cement mineral composition does not vary and the quality is stable. Can be used.

(D) Raw material preparation step The production method of the present invention further includes, as an optional step, a raw material preparation step (D) for preparing a clinker raw material before the step (A).
In this process, clinker raw materials such as calcium raw material, silicon raw material, aluminum raw material, and iron raw material are blended using the Borg formulas of the formulas (1) to (4) so as to be within the range of the cement mineral composition. To prepare a mixed raw material. Here, examples of the calcium raw material include limestone, quick lime, and slaked lime, the silicon raw material includes silica and clay, the aluminum raw material includes clay, and the iron raw material includes iron cake and iron cake.
Since the chemical composition of the mixed raw material before firing is often almost the same as the chemical composition of the clinker after firing, in order to obtain a clinker having the cement mineral composition, it is usually calculated based on the Borg equation. It is sufficient to prepare the raw materials so as to satisfy the mineral composition. However, for the sake of accuracy, a part of the mixed raw material is fired in an electric furnace or the like, and the correlation between the chemical composition in the raw material and the clinker obtained by firing is grasped in advance. It is preferable to correct the mixing ratio of the raw materials so that the target mineral composition in the clinker is obtained.

As the raw material, in addition to natural raw materials, industrial waste, general waste, and / or waste such as construction generated soil can be used as part of the raw material.
The industrial waste is, for example, coal ash, slag, ready-mixed concrete sludge, construction sludge, steelmaking sludge, boring waste soil, incineration ash, foundry sand, rock wool, blast furnace secondary ash, construction waste, concrete waste, etc. One or more selected may be mentioned.
Examples of the general waste include one or more selected from purified water sludge, sewage sludge, sewage sludge dry powder, municipal waste incineration ash, shells, sewage sludge incineration ash, and the like.
Examples of the construction-generated soil include soil generated from construction sites and construction sites, residual soil, and the like.
In addition, when it is necessary to adjust the fineness of the mixed raw material, the raw material is pulverized and adjusted to a predetermined fineness with a pulverizer such as a ball mill.

2. Molded Product Next, the molded product charged in the step (B) will be described.
The molded article is obtained by molding a composition containing (a) coal ash, (b) a binder, and (c) water.
Hereinafter, the components will be described in detail according to (1) each component of the composition, (2) the composition of the composition, (3) the shape and strength of the molded product, and (4) the method for producing the molded product. In the present invention, “molding” includes “granulation”.

(1) Each component of composition (a) Coal ash The coal ash used by this invention is not specifically limited, For example, when pulverized coal is burned in a coal-fired power plant, an oil refinery factory, other chemical factories, etc. Examples of the powder collected by the dust collector from the generated combustion gas. The brane specific surface area of the coal ash is not particularly limited, and is, for example, 2500 to 6000 cm ² / g.
The carbon content of coal ash is preferably 3% or more, more preferably 4 to 50%, still more preferably 5 to 45%, and particularly preferably 6 to 40%. If the value is less than 3%, the calorific value is small and the effect of reducing the fuel cost is reduced.

(B) Binder The binder used in the present invention includes the following organic binders and inorganic binders.
(i) Organic binder Organic binders include, for example, starches, polyvinyl alcohol, cellulose derivatives, polyalkylene oxides, polycarboxylic acids, polyvinyl pyrrolidone, polyvinyl acetate, polyurethane, ethylene / vinyl acetate resin, styrene / butadiene rubber, and natural rubber. , Agar, and one or more selected from gelatin.

Examples of the starches include starch, modified starch such as pregelatinized starch, oxidized starch, and starch derivatives, and dextrin.
Examples of the cellulose derivative include carboxymethylcellulose and salts thereof, hydroxypropylmethylcellulose, hydroxypropylcellulose, hydroxyethylcellulose, ethylcellulose, and hydroxymethylcellulose.
Examples of the polyalkylene oxide include polyethylene oxide, polypropylene oxide, and a copolymer of ethylene oxide and propylene oxide.
Examples of the polycarboxylic acids include polyacrylic acid and salts thereof, polyacrylic acid esters, polymethacrylic acid and salts thereof, and polymethacrylic acid esters. Polycarboxylic acids include both homopolymers and copolymers.
Among these organic binders, starches and polyvinyl alcohol are preferable because they impart moderate plasticity to coal ash, have excellent formability, and are easy to mold.

In particular, the content of amylose and amylopectin in the starches is preferably 10% or more and less than 90%, more preferably 13% or more and less than 87%, still more preferably 15% or more and less than 85%, respectively. .
If the content of amylose is 10% or more, the paste is easily aged (crystallized) and the hardness is increased, so that the strength of the molded product is improved. Moreover, if the content rate of amylopectin which raises the viscosity of glue is less than 90%, the viscosity of glue will fall and kneading | mixing of a composition will become easy.
Here, starches having amylose and amylopectin content of 10% or more and less than 90% are, for example, corn starch, wheat starch, rice starch, bean starch, potato starch, glutinous rice starch, sweet potato starch, and tapioca starch. And the modified starch made from these starches as raw materials.
Of the organic binders, the water-soluble binder is mainly used in the form of an aqueous solution (including paste), and the water-insoluble binder is mainly used in the form of an emulsion.

(Ii) Inorganic binder The inorganic binder is selected from, for example, cement, gypsum powder, pozzolanic powder, silica powder, limestone powder, cement kiln dust, expansion material, construction generated soil powder, incinerated ash, slag powder, and clay powder 1 More than species.
The cement is not particularly limited, and is selected from ordinary Portland cement, early strength Portland cement, super early strength Portland cement, medium heat Portland cement, low heat Portland cement, blast furnace cement, silica cement, and ordinary ecocement 1 More than species.
Examples of the gypsum powder include at least one selected from dihydrate gypsum, flue gas desulfurization gypsum, phosphate gypsum, titanium gypsum, hydrofluoric gypsum, refined gypsum, hemihydrate gypsum, and anhydrous gypsum.
The slag powder is selected from blast furnace granulated slag, blast furnace slow-cooled slag, converter slag, secondary refining slag, electric furnace system slag, ferronickel slag, copper slag, electric furnace oxidation slag, and coal gasification molten slag 1 type or more is mentioned. Among these, blast furnace granulated slag is preferable because of its excellent hydraulic potential.
Examples of the pozzolanic powder include one or more selected from volcanic ash, shirasu, volcanic rock powder, silicate clay powder, and the like.

The cement kiln dust preferably has a K ₂ O content of 5 to 40%, a Cl content of 3 to 30%, and an SO ₃ content of from the viewpoint of long-term strength development of the cement composition. It is 5 to 20%, and chlorine bypass dust is particularly preferable.
Examples of the clay powder include one or more selected from bentonite, kaolin, talc, acid clay, attapulgite, sepiolite, diatomaceous earth, sericite, and zeolite.
Examples of the expansion material include calcium sulfoaluminate-based expansion material and lime-based expansion material, and the construction-generated soil powder includes soil and residual soil generated from a construction site, a construction site, etc. Examples include sewage sludge incineration ash, municipal waste incineration ash, and RDF incineration ash.

Among these inorganic binders, cement is preferable, and more preferably, since it is excellent in early strength development and can increase the production efficiency of the granulated product, ordinary Portland cement, early strong Portland cement, ultra early strong Portland cement And ordinary eco-cement.
The Blaine specific surface area of the inorganic binder is preferably 2000 to 10000 cm ² / g, from the viewpoint of cost, availability, ease of molding and strength of the molded product, and strength development of the cement composition. Preferably it is 2500-9000 cm < ² > / g, More preferably, it is 3000-8000 cm < ² > / g.
The organic binder and inorganic binder may be used together in addition to being used alone.

(C) Water Water is not particularly limited, and examples thereof include tap water, reclaimed water, sewage treated water, and water separated from fresh concrete sludge.

(2) Composition Blending Next, the composition blending will be described.
The composition containing an organic binder preferably contains 95 to 99.5% coal ash and 0.5 to 5% organic binder, and 2 to 35 water with respect to 100 parts by mass of the coal ash and the organic binder in total. Includes mass parts.
The reason why the blending ratio of the composition is specified in the above range and the more preferable blending ratio ranges are as follows (i) to (iii).
(I) When the blending ratio of coal ash is less than 95%, the amount of coal ash input to the cooler is relatively small, and when it exceeds 99.5%, the amount of organic binder is relatively small and the strength of the molded product is reduced. There is a case. The blending ratio of coal ash is more preferably 96 to 99%. Therefore,
(Ii) If the blending ratio of the organic binder is less than 0.5%, the strength of the molded product may decrease. In addition, if it exceeds 5%, the amount of coal ash input to the cooler decreases, the strength of the molded product becomes excessive, and pulverization may be difficult in the (C) mixture pulverization step, which is a subsequent step. Accordingly, the manufacturing cost (crushing cost) of the cement composition increases. The blending ratio of the organic binder is more preferably 1 to 4%.
(Iii) If the mixing ratio of water is less than 2 parts by mass, molding may be difficult, and if it exceeds 35 parts by mass, problems such as adhesion of the composition (kneaded material) to a molding apparatus or the like tend to occur during molding. The blending ratio of water is more preferably 3 to 30 parts by mass, further preferably 5 to 25 parts by mass, and particularly preferably 10 to 20 parts by mass with respect to 100 parts by mass in total of the coal ash and the organic binder.

  The composition containing an inorganic binder preferably contains 60 to 99.5% coal ash and 0.5 to 40% inorganic binder, and water is added to 100 parts by mass of the coal ash and the inorganic binder in total. Including ~ 35 parts by mass.

The reason why the blending ratio of the composition is specified in the above range and the more preferable blending ratio ranges are as follows (a) to (e).
(A) When the blending ratio of coal ash is less than 60%, the amount of coal ash input to the cooler is relatively small, and when it exceeds 99.5%, the amount of inorganic binder is relatively small and the strength of the molded product is reduced. There is a case. The blending ratio of coal ash is more preferably 70 to 96%, still more preferably 78 to 94%. Therefore,
(B) If the blending ratio of the inorganic binder is less than 0.5%, the strength of the molded product may decrease. On the other hand, if it exceeds 40%, the input amount of coal ash is reduced, and the strength of the molded product becomes excessive, which may make pulverization difficult in the subsequent (C) mixture pulverization step. Further, the manufacturing cost (grinding cost) of the cement composition increases. The blending amount of the inorganic binder is more preferably 3 to 15%, and further preferably 4 to 12%.
(C) When the mixing ratio of water is less than 2 parts by mass, it may be difficult to knead the powder, and when it exceeds 35 parts by mass, the composition (kneaded material) may adhere to a granulator or the like during molding Is likely to occur. As for water content, 3-30 mass parts is more preferable with respect to 100 mass parts of total amounts of powder, 5-25 mass parts is more preferable, 10-20 mass parts is especially preferable.

  Moreover, in order to increase the usage-amount of coal ash, the content rate of CaO in the mixture of coal ash and a binder becomes like this. Preferably it is less than 10%, More preferably, it is 1-9%, More preferably, it is 2-8%. If the value is 10% or more, the amount of quicklime produced increases as the amount of the molded product increases, and the concrete using the cement composition containing the quicklime may be cracked due to expansion due to the hydration of quicklime. is there.

(3) Form and strength of molded product The shape of the molded product is not particularly limited, and examples thereof include a spherical shape, an ellipsoidal shape, a cylindrical shape, a plate shape, a rectangular parallelepiped shape, and a cubic shape.
The size of the molded product is preferably 1 to 60 mm, more preferably 3 to 50 mm, and still more preferably 5 to 40 mm. When the value is in the range of 1 to 60 mm, the molding can be easily put into the cooler. The “size of the molded product” refers to the maximum dimension of the molded product (for example, the length of the long axis when the cross section is elliptical).
In order to prevent the reaction with the clinker, it is preferable that the molded product does not collapse due to an impact when charged into the cooler, and the characteristic value of the molded product can be shown by using the crushing strength and the drop strength.

The method for measuring the crushing strength and preferred values of the strength are as follows.
(I) A spherical granulated product having the same composition as that of the molded product is prepared with a pan pelletizer, and then granulated with a particle size of 4.75 to 9.5 mm (size of sieve openings) from the granulated product. Choose 10 items.
(Ii) As shown in FIG. 1, the crushing strength is measured by applying pressure from both sides of the granulated product, and the crushing strength is averaged to obtain an average value of crushing strength.
The crushing strength is preferably 4N or more, more preferably 5N or more, further preferably 6N or more, and particularly preferably 7N or more. A molded product having a value of 4N or more is unlikely to collapse due to an impact when charged into a cooler. On the other hand, since crushing becomes difficult when the crushing strength is too high, the upper limit value of the strength is preferably 2000 N, more preferably 1500 N, still more preferably 1000 N, particularly preferably 800 N, and most preferably 500 N.

Moreover, the measurement method of drop strength and the preferable value of this strength are as follows.
(I) A spherical granulated product having the same composition as that of the molded product is prepared with a pan pelletizer, and then granulated with a particle size of 4.75 to 9.5 mm (size of sieve openings) from the granulated product. About 1 kg of a sample is collected and the mass (a) is measured.
(Ii) After allowing the granulated material to fall freely from a height of 1 m with respect to the iron plate surface, collect the entire amount of the granulated material (falling material) on the iron plate, drop this whole amount again, Repeat the operation four times in total.
(Iii) After all four free drops have been completed, the total amount of the granulated material (falling material) is screened with a 2.5 mm sieve, and the remaining mass (b) remaining on the screen is measured.
(Iv) The drop strength is calculated by substituting the masses (a) and (b) into the following formula.
Drop strength (%) = b / a × 100
The drop strength is preferably 70% or more, more preferably 75% or more, still more preferably 80% or more, and particularly preferably 85% or more. Molded articles having a value of 70% or more are less likely to collapse due to impact upon charging into the cooler.

(4) Manufacturing method of molded product This method is to mold the kneaded product after kneading the composition.
For kneading the composition, for example, a general-purpose kneader for preparing a paste is used. In this case, each component of the composition is charged all at once into the kneader or separately. When charging separately, the order of adding each component is not particularly limited. For example, after mixing the powder components, water may be added thereto and kneaded. The kneading of the composition may be performed simultaneously with the molding in the molding apparatus.
The molding apparatus is not particularly limited, and examples thereof include a pan pelletizer, a briquette machine, a roll press, an extrusion molding machine, and a pug mill. Further, after molding, the molded product may be sized using a rotating drum, a mixer, a sieve or the like. The fine powder generated during molding can be screened and recovered, and then used again as a raw material for the molded product.

In the case of a molded product containing cement as a binder, the curing period of the molded product is not particularly limited, but in order to obtain sufficient strength, it is preferably 1 hour, more preferably 3 hours or more, and even more preferably 6 hours or more. It is. Moreover, although the upper limit of a curing period is not specifically limited, From the point of manufacturing efficiency, Preferably it is 30 days or less, More preferably, it is 10 days or less, More preferably, it is 5 days or less.
The curing method is not particularly limited, and examples thereof include one or more selected from sealed drying curing, air drying curing (air drying curing), wet air curing, steam curing, heat drying curing, and carbon dioxide curing. Among these, from the viewpoint of promoting strength, sealed dry curing, wet air curing at a relative humidity of 80% or more, carbon dioxide gas curing, and the like are preferable, and steam curing and heating curing are preferable when it is desired to develop strength at an early stage. . Here, the temperature of sealed dry curing, air drying curing, or the like is, for example, 5 to 40 ° C., and the temperature of steam curing or heat drying curing is, for example, 30 to 400 ° C.

When the surface of the molded product is carbonated, the surface of the molded product becomes dense due to the generated calcium carbonate, and the surface hardness is increased. The increase in strength due to carbonation inside the object is small compared to the surface. Therefore, the molded product whose surface is carbonated is difficult to be pulverized by the impact during transportation and the friction between the molded products, but it is relatively easy to pulverize in the pulverization process of cement production.
The degree of carbonation in the carbon dioxide curing is preferably sufficient if the phenolphthalein solution fades colorless on a part of the surface of the molded product. Since the phenolphthalein solution fades from reddish purple to colorless in a neutral range of pH 8.3 or less, the carbonation (neutralization) of the surface proceeds by a simple operation of spraying the solution onto a molded product. The degree can be easily determined.
The method of curing carbon dioxide is a method of exposing a molded product to air, a method of exposing to a carbon dioxide gas, a method of immersing in an aqueous solution of carbonate (salt) such as carbonated water, ammonium hydrogen carbonate or ammonium carbonate, and applying the aqueous solution to the molded product. The method of spraying etc. are mentioned. The carbon dioxide used for the carbon dioxide curing may be an exhaust gas containing carbon dioxide recovered from a cement production facility in addition to industrial carbon dioxide or carbon dioxide in the air.
In addition to performing the carbon dioxide curing alone, it may be used in combination with the other curing described above.
The molded article may be cured as necessary, and is unnecessary when the desired strength is obtained at an early stage.

3. Fuel Cost Reduction Effect Next, the fuel cost (fuel cost) reduction effect in the present invention will be described.
Using the production method of the present invention, for example, as shown in the examples below, a molded product containing coal ash having a carbon content of 10% is converted to 2% in terms of coal ash with respect to 100 parts by mass of cement clinker. When mass parts, 12 parts by mass, and 49 parts by mass are used, the fuel cost reduction per ton of cement clinker is 52 yen, 288 to 354 yen, and 864 yen, respectively.
By the way, if the reduction amount (864 yen / 1 ton of cement clinker) is applied to 1,4330,000 tons, which is the production amount of blast furnace cement B type in 2009, the reduction of fuel cost will be about 11 billion yen per year. As a result, coal resources used as fuel can be saved.

EXAMPLES Hereinafter, although this invention is demonstrated using an Example and drawing, this invention is not limited to these Examples.
1. Materials used (1) Coal ash Coal ash (a): Carbon content 10%, CaO content 9.0%
Coal ash (b): Carbon content 2.3%, CaO content 9.0%
(2) Starch Sanwa Corn Alpha Y (trade name, manufactured by Sanwa Starch Kogyo Co., Ltd.), amylose content: 25%, amylopectin content: 75%
(3) Polyvinyl alcohol (PVA)
POVAL laundry paste SANNOL (registered trademark, manufactured by Sanwa Yushi Kogyo Co., Ltd.)
(4) Cement Normal Portland cement (manufactured by Taiheiyo Cement)
(5) cement kiln dust chemical _{composition: K 2 O; 6.5%,} Cl; 4.0%, SO 3; 10.0%, CaO; 51.0%
Blaine specific surface area: 5000 cm ² / g
(6) Sand Standard sand specified in JIS R 5201 (7) Water reducing agent Polycarboxylic acid-based high performance AE water reducing agent Leo build SP8N (registered trademark, manufactured by BASF Pozzolith)
(8) Gypsum Dihydrate gypsum: Grade 1 reagent, manufactured by Kanto Chemical Co. Hemihydrate gypsum: Grade 1 reagent, manufactured by Kanto Chemical Co., Ltd. (9) Blast furnace slag powder Slag (a): Blaine specific surface area: 4000 cm ² / g (Esment Kanto) (Made by company)
Slag (b): Blaine specific surface area: 12000 cm ² / g (crushed product of slag (a))
(10) Silica powder Blaine specific surface area: 7000 cm ² / g
(11) Silica fume BET specific surface area: 20 m ² / g

2. Preparation of molded product (granulated product) After using the coal ash (a) to prepare a composition by mixing various components in accordance with the composition of the composition shown in Table 1, the composition was prepared using a Hobart mixer. Various kneaded materials were obtained by kneading. Next, the kneaded product was put into a pan pelletizer to prepare wet molded products (Examples 1 to 14 and Comparative Examples 1 to 4) having a particle size of 2 to 25 mm. Further, among these, the molded products containing cement as a binder (Examples 6 to 8) were sealed and cured at 20 ° C. for 1 day, and then air-dried at 20 ° C. for 3 days.
Further, for comparison, in accordance with the heavy processing by mixing coal ash and liquid, which is preferable in Patent Document 1, 20 parts by mass of water is added to 100 parts by mass of coal ash and kneaded. In the same manner as above, a molded product containing only coal ash and water (Comparative Example 5) was produced.

3. Production of cement composition Ordinary Portland cement clinker containing 59.1% C ₃ S, 16.9% C ₂ S, 9.9% C ₃ A, and 10.2% C ₄ AF, rotary kiln 5 The molded products (Examples 1 to 14 and Comparative Examples 1 to 4) in amounts shown in Table 1 with respect to 100 parts by mass of the clinker (Examples 1 to 14 and Comparative Examples 1 to 4) are clinkered from 8 before the kiln. The mixture was added to the dropping point 10 (temperature is 1400 ° C.) to obtain a mixture of clinker and molded product. When the molded products in these mixtures were visually observed, the molded products of Examples 1 to 14 remained in their original shapes without collapsing.
Next, after adding 1.3 parts by mass of dihydrate gypsum in terms of SO ₃ and 1.3 parts by mass of hemihydrate gypsum in terms of SO ₃ to 100 parts by mass of the mixture of the clinker and the molded product, a small mill To produce cement compositions (Examples 1 to 14 and Comparative Examples 1 to 4) having a Blaine specific surface area of 3300 cm ² / g.

  For comparison with Example 8, a powder mixture containing 90% coal ash (b), 9% ordinary Portland cement, and 1% cement kiln dust was added to 33 parts by mass of 100 parts by mass of the ordinary Portland cement clinker. After mixing by mass and pulverizing, gypsum was mixed in the same manner as in the above example to produce a cement composition (Comparative Example 6) containing coal ash (carbon content 2.3%).

Furthermore, in order to confirm the effect of removing carbon in the carbon removal process of the present invention, the heat treated coal ash having a carbon content of 1% or less by heat-treating the coal ash (a) at 800 ° C. ² / g) is mixed with 49 parts by mass (however, in terms of coal ash before heat treatment) with respect to 100 parts by mass of the ordinary Portland cement clinker, and then gypsum is mixed in the same manner as in the above-described examples, A cement composition (Comparative Example 7) was prepared.

4). Measurement of Crushing Strength According to the method for measuring crushing strength, the crushing strength was measured using the molded products (granulated products) of Examples 1 to 14 and Comparative Example 5.
As a result, for the molded products of Examples 1 to 14, the average value of the crushing strength was obtained by averaging 10 crushing strength values obtained in each case, but 10 molded products of Comparative Example 5 were obtained. Since the crushing strength was too low for four of the molded products, the remaining six values were averaged to obtain the average crushing strength. The measurement result of the crushing strength is shown in Table 1. The crushing strength was measured at the stage when the granulated product was put into a cooler.

5. Measurement of drop strength According to the method for measuring drop strength, the drop strength was measured using the molded products (granulated products) of Examples 1 to 14 and Comparative Examples 1 to 5. The results are shown in Table 1.
In addition, the said drop strength was also measured in the step which throws a granulated material into a cooler.

6). Measurement of Cement Composition Flow, etc. The fluidity of the cement compositions of Examples 1, 6, 9, 10, 13 and Reference Examples was determined by measuring flow values according to the following (i) and (ii).
(I) Using the cement composition, a mortar of fine aggregate / cement = 2, water / cement = 0.35, and water reducing agent (solid content) /cement=0.007 in terms of mass ratio Using a mixer, mortar was prepared by kneading at low speed for 2.5 minutes and then at high speed for 3 minutes.
(Ii) The mortar immediately after kneading and 30 minutes after kneading is put into a mini slump cone (steel slump cone as defined in JIS A 1171: 2000 “Testing method for polymer cement mortar”). The fluidity was determined by measuring the spread (flow value) of the mortar when the was removed upward.
The setting time of the cement composition and the compressive strength of the mortar were measured according to JIS R 5201. The results are shown in Table 1.

7). About flowability and setting As shown in Table 1, the flow value of the mortar of the cement composition of Example 10 in which the amount of the molded product is as large as 43 parts by mass is 320 mm immediately after kneading and 180 mm after 30 minutes, These are higher than the flow value of normal Portland cement mortar (270 mm immediately after kneading, 160 mm after 30 minutes).
In addition, the setting in Example 10 has an initial time of 2 hours and 55 minutes and an end time of 5 hours, and is equivalent to the normal Portland cement setting (initial time is 2 hours and 20 minutes, and the end time is 3 hours and 30 minutes). Termination is within a range that does not cause a problem in practice.

8). About compressive strength Comparing the compressive strengths of Example 8 and Comparative Example 6 containing the same binder and containing the same amount (33 parts by mass) of coal ash, 33.2 N / mm ² at a material age of 7 days, respectively. and ^{33.5N / mm 2, 51.5N / mm} 2 and 52.8N / mm ² at the age of 28 days, an age of June 76.0N / mm ² and 69.5N / mm ^2, age of 1 year 78.7 N / mm ² and 71.5 N / mm ² . Therefore, compared with the powder composition of Comparative Example 6, the cement composition according to the present invention is equivalent in strength development in the early and middle age of the material 7 days and 28 days, and after the age of 6 months. The strength development at a long age is higher.
Further, the same amount when comparing Example 3 with compressive strength of Comparative Example 7 containing a coal ash (49 parts by mass), respectively, 33.4N / mm ² and 31.8N / ^mm 2 at an age of 7 days, 52.0N / mm ² and 50.1N / mm ² at the age of 28 days, 75.4N / mm ² and 69.8N / mm ² at the age of June, and 79.2N / mm ² in one year age of 70.5 N / mm ² . Therefore, the cement composition according to the present invention is superior in strength development at all ages as compared with a cement composition (powder composition) containing heat-treated coal ash.
From the above results, the cement composition according to the production method of the present invention has a higher cooling rate of the clinker than when the clinker is simply cooled by a cooler by heat exchange between the clinker and the molded article in the carbon removal step. Therefore, it is estimated that the hydraulic property of the clinker is improved.
Further, the compressive strength of Example 13 using a blast furnace slag (inorganic binder) having a Blaine specific surface area of 4000 cm ² / g was particularly higher than that of Comparative Example 3 using a blast furnace slag of 12000 cm ² / g. High at day and age 7 days.

9. About reduction effect of fuel cost As above-mentioned, 2 mass parts (Example 1) and 12 masses of the moldings using coal ash with a carbon content of 10% with respect to 100 mass parts of clinker, respectively, in terms of coal ash Parts (Examples 2 and 4) and 43 parts by mass (Example 12), the fuel cost reduction per ton of cement clinker is 52 yen, 288 to 354 yen, and 965 yen, respectively. .
In Examples 2 and 4, although the same amount (12 parts by mass) of the molded product was introduced, the fuel cost reduction was different from 288 yen and 354 yen because of the organic binder that is also the fuel Based on the difference in content (2% and 5%).

10. Others The amount of air in the mortar of the cement compositions of Examples 1 to 14 was equivalent to the amount of air in the mortar of ordinary Portland cement. Further, darkening (carbon) was observed on the surface of the mortar of Comparative Example 5, but no darkening was observed on the surfaces of the mortars of the cement compositions of Examples 1-14.

  From the above, the method for producing a cement composition of the present invention can use a large amount of coal ash having a high carbon content, and the effect of reducing the production cost of clinker, particularly the fuel cost, is extremely high. Further, the cement composition obtained by the production method of the present invention has high quality and is stable.

1 Molded product (specimen)
2 Compression tester (autograph)
3 Upper member 4 Lower member 5 Rotary kiln 6 Pre-heater 7 Cooler 8 Front of kiln 9 Main burner 10 Clinker drop point

Claims (5)

The manufacturing method of the cement composition including the following (A)-(C) process.
Cement mineral composition calculated using (A) Borg formula, 20-80% by _{C 3} S, 5 to 60% for _{C 2} S, 1 to 16% in the _{C 3} A, and at _C 4 AF 6 to 16 Cement clinker firing step (B) for firing cement clinker that is 100% by weight 0.2 to 100.0 of a molded product obtained by molding a composition containing coal ash, a binder, and water with respect to 100 parts by mass of the cement clinker. A carbon removal step (C) in which the carbon and organic matter contained in the molded product are burned and removed while being mixed with a cement clinker at a ratio of part by mass in an area of 800 to 1400 ° C. in the cooler. Mixture crushing step of crushing mixture (a) of cement clinker and molded product, or mixture (b) obtained by adding gypsum to mixture (a)   The binder is selected from starches, polyvinyl alcohol, cellulose derivatives, polyalkylene oxides, polycarboxylic acids, polyvinyl pyrrolidone, polyvinyl acetate, polyurethane, ethylene / vinyl acetate resin, styrene / butadiene rubber, natural rubber, agar, and gelatin. The manufacturing method of the cement composition of Claim 1 which is 1 or more types of organic binders. The binder is one or more inorganic binders selected from cement, gypsum powder, pozzolanic powder, silica powder, limestone powder, cement kiln dust, expansion material, construction generated soil powder, incinerated ash, slag powder, and clay powder. The method for producing a cement composition according to claim 1, wherein the inorganic binder has a specific surface area of 2000 to 10,000 cm ² / g.   In the step (C), the mixture (a) or the mixture (b) is further selected from blast furnace slag grains, blast furnace slag powder, fly ash, coal ash, silica powder, limestone, limestone powder, and cement kiln dust. The manufacturing method of the cement composition of any one of Claims 1-3 which grind | pulverizes the mixture (c) formed by adding 1 or more types.   The manufacturing method of the cement composition of any one of Claims 1-4 whose carbon content rate of the said coal ash is 3 mass% or more.

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