JP2016008159A - Method for producing blast furnace slag fine powder, and method for producing blast furnace cement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for precisely predicting an activity index and sorting excellent blast furnace slag even if quality of the blast furnace slag varies widely.SOLUTION: A method for producing blast furnace slag fine powder having the Cl content of 450-800 mg/kg comprises a step of simultaneously mixing/pulverizing the blast furnace slag, gypsum, limestone and an inorganic substance containing chlorine. The blast furnace slag fine powder contains 90-98 mass% of the blast furnace slag, 0.5-5.0 mass% of the gypsum and 0.5-5 mass% of the limestone.

Description

  The present invention relates to a method for producing fine blast furnace slag powder, which can efficiently obtain the strength expression of blast furnace cement by adding an inorganic substance containing chlorine at the time of producing the blast furnace cement. Moreover, it is related with the manufacturing method of the blast furnace cement which uses this blast furnace slag fine powder.

Blast furnace granulated slag produced from steelworks is approximately 20 million tons in 2012, of which approximately 90% is used as cement raw material. Among them, the quality of the slag used for the blast furnace cement greatly affects the quality of the blast furnace cement, and the basicity ((CaO + MgO + Al ₂ O ₃ ) defined in JIS (JIS A 6206 “Blast furnace slag fine powder for concrete”). ) / SiO ₂ ) is treated as a quality control index value of blast furnace slag.

  In addition, it has been found that the manufacturing conditions such as the hot metal temperature and cooling rate of the blast furnace slag affect the quality of the blast furnace slag (for example, Non-Patent Document 1).

  Thus, due to variations in chemical components and manufacturing conditions of the blast furnace slag, the activity of the slag may be reduced, and the strength development of the blast furnace cement may be reduced. In this case, it is necessary to take various actions as a strength complementation measure.

  Meanwhile, the cement industry uses chlorine-rich waste (such as municipal waste incineration ash and waste plastic) as a raw material for cement. However, in the production of clinker, chlorine induces coating troubles in the cement raw material firing system and increases the chlorine content in the cement clinker. For this reason, for the purpose of reducing the content of alkali chloride and the like in the cement raw material firing system, for example, a chlorine bypass device as shown in Patent Document 1 is additionally installed in the cement kiln. Chlorine bypass dust contains chlorides such as KCl, calcined cement raw materials, and sulfates thereof.

  Conventionally, various methods have been proposed for effective use of chlorine bypass dust. For example, Patent Document 2 proposes a method for improving the strength of cement by adding chlorine bypass dust to blast furnace cement. Patent Document 3 proposes a method of reducing chlorine leaching amount by adding chlorine bypass dust to blast furnace cement.

Mitsuo Hanada, Hidehiko Miyairi, Satoshi Kawauchi, Research on Blast Furnace Cement, Annual Report of Cement Technology, pp.171-175, Vol.20 (1966)

Japanese Patent Laid-Open No. 10-330136 JP-A-10-218657 JP 2008-174409 A

  However, the addition of chlorine bypass dust as in Patent Document 2 increases the amount of chlorine in the cement and may cause corrosion of reinforcing bars in the concrete structure.

  Therefore, an object of the present invention is to provide a blast furnace slag powder and a method for producing a blast furnace cement capable of efficiently obtaining the strength expression of the blast furnace cement with a small amount of chlorine at the time of producing the blast furnace cement and suppressing corrosion of the reinforcing bars.

  As a result of intensive studies to achieve the above object, the present inventors have obtained a method for producing blast furnace slag powder and a method for producing blast furnace cement that can efficiently obtain the strength expression of blast furnace cement by adding a small amount of chlorine during the production of blast furnace cement. The method has been found and the present invention has been completed.

  That is, the present invention provides a blast furnace slag fine powder that simultaneously mixes and pulverizes blast furnace slag, gypsum, limestone, and chlorine-containing inorganic substance to produce a blast furnace slag fine powder having a Cl content of 450 to 800 mg / kg. It relates to the manufacturing method.

  According to the production method of the present invention, it is possible to provide a method for producing blast furnace slag fine powder that can efficiently obtain the strength expression of blast furnace cement with the addition of a small amount of chlorine.

  Moreover, this invention relates to the manufacturing method of blast furnace cement which mixes 30-60 mass% of blast furnace slag fine powder, and 40-70 mass% of cement.

  According to the production method of the present invention, it is possible to provide a method for producing blast furnace cement, which can efficiently obtain the strength expression of blast furnace cement with the addition of a small amount of chlorine.

  According to the method for producing blast furnace slag fine powder according to the present invention, it is possible to provide a method for producing blast furnace slag fine powder, which can efficiently obtain the strength expression of blast furnace cement with the addition of a small amount of chlorine. Moreover, according to the method for producing a blast furnace cement according to the present invention, it is possible to provide a method for producing a blast furnace cement capable of efficiently obtaining the strength of the blast furnace cement with the addition of a small amount of chlorine.

It is a graph which shows the relationship between the amount of chlorine of blast furnace cement, the amount of chlorine in blast furnace slag fine powder, and compressive strength ratio.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  <Manufacturing method of blast furnace slag fine powder>

  In the method for producing a blast furnace slag fine powder according to this embodiment, a blast furnace slag fine powder is produced by simultaneously mixing and pulverizing blast furnace slag, gypsum, limestone, and an inorganic substance containing chlorine. Here, mixing and pulverizing at the same time means that the respective materials are charged almost simultaneously into a pulverizer such as a vertical pulverizing mill or a tube mill and pulverized. By pulverizing at the same time, it is estimated that the blast furnace slag powder is covered with an inorganic substance containing chlorine and the hydration activity is increased.

The inorganic substance containing chlorine is preferably at least one selected from chlorine bypass dust, NaCl, KCl, CaCl _{2 and the} like. Especially when chlorine bypass dust is used, it leads to effective utilization of industrial by-products.

Chlorine bypass dust is dust collected from the exhaust gas extracted by the chlorine bypass device. The solid substance of this chlorine bypass dust consists of chlorides such as KCl, NaCl, CaCl ₂ , calcined cement raw materials, sulfates thereof, and the like.

  The amount of the inorganic substance containing chlorine is such that the Cl content in the produced blast furnace slag fine powder is 450 to 800 mg / kg, more preferably 550 to 790 mg / kg, still more preferably 600 to 780 mg / kg, particularly preferably. Adjust to 630-770. If it is 450 mg / kg or less, it is not sufficient to supplement the strength of blast furnace cement, and if it is 800 mg / kg or more, it is preferable because the setting time of cement may be shortened or rebar corrosion in concrete structures may be caused. Absent.

  The limestone desirably satisfies the quality specified in JIS R 5210 “Portland cement”. The amount of limestone added is 0.5 to 5% by mass, preferably 0.7 to 4% by mass, based on the blast furnace slag fine powder. If it is this range, sufficient intensity | strength expressiveness can be acquired.

  It is desirable that the gypsum satisfies the quality specified in JIS R 9151 “natural gypsum for cement”. Specifically, dihydrate gypsum, hemihydrate gypsum, and insoluble anhydrous gypsum are suitably used for the cement composition.

The blast furnace slag is composed of 30 to 40% by mass of SiO ₂ , 10 to 20% by mass of Al ₂ O ₃ , 30 to 50% by mass of CaO, ₃ to 10% by mass of MgO, 0.1 to Fe ₂ O ₃ . 5.0 wt%, a Na ₂ O 0.1 to 0.4 wt%, the _{K 2} O 0.2 to 0.6 wt%, the TiO ₂ 0.2 to 0.6 wt%, the MnO 0 It is preferable to contain 0.1-0.3 mass% and Cl 0.001-0.010 mass%.

The SiO ₂ 31 to 39 wt%, the _Al 2 _{O 3} 11 to 19 wt%, the CaO 31 to 49 wt%, the MgO from 3.5 to 9.5 mass%, the _Fe 2 _{O 3} 0.2 to 4 .5 wt%, a Na ₂ O 0.15 to 0.35 wt%, the _{K 2} O 0.25 to 0.55 wt%, the TiO ₂ 0.25 to 0.55 wt%, the MnO 0. It is more preferable to contain 15-0.28 mass% and 0.0015-0.0095 mass% of Cl.

The SiO ₂ 32 to 38 wt%, the _Al 2 _{O 3} 12 to 18 wt%, the CaO 32-48 wt%, the MgO 4.0 to 9.0 wt%, the _Fe 2 _{O 3} 0.3 to 4 .0 wt%, a Na ₂ O 0.20 to 0.30 wt%, the _{K 2} O 0.27-.50 wt%, the TiO ₂ from 0.30 to .53 wt%, and MnO 0. More preferably, it contains 17 to 0.26% by mass and 0.0020 to 0.0090% by mass of Cl.

The SO ₃ content of the blast furnace slag fine powder is preferably 1.0 to 2.5% by mass, more preferably 1.1.0 to 2.4% by mass, and still more preferably 1.2 to 2.3% by mass. The amount of gypsum added is adjusted so that If it is less than 1.0% by mass, it will adversely affect the setting and fluidity of the blast furnace cement, and if it is more than 2.5% by mass, the amount of slag used will decrease and the performance as a blast furnace cement will be unfavorable.

The fineness of the blast furnace slag fine powder according to the present invention is preferably 3500 to 4500 cm ² / g, more preferably 3600 to 4400 cm ² / g, and further preferably 3700 to 4300 cm ² / g. Is less than the fineness is 3500 cm ² / g of ground granulated blast furnace slag, and reduced strength development of blast furnace cement, greater than 4500cm ² / g, increases the manufacturing cost of the ground granulated blast furnace slag.

<Manufacturing method of blast furnace cement>
Next, the manufacturing method of the blast furnace cement concerning this invention is demonstrated.

  The blast furnace cement production method uses the blast furnace slag fine powder obtained in the above-described production process of the blast furnace slag fine powder.

  The said blast furnace cement mixes 30-60 mass% of blast furnace slag fine powder, and 40-70 mass% of Portland cement. Preferably 40-50 mass% of blast furnace slag fine powder and 50-60 mass% of Portland cement are mixed. More preferably, blast furnace slag fine powder 42-48 mass% and Portland cement 52-58 mass% are mixed. Within this range, the chlorine added to the blast furnace slag powder can efficiently enhance the strength of the blast furnace cement.

  The manufacturing method of the Portland cement composition used for the blast furnace cement of the present invention comprises mixing raw materials selected from the group consisting of limestone, meteorite, coal ash, clay, blast furnace slag, construction generated soil, sewage sludge, copper squeeze and incineration ash. And firing to produce a cement clinker, and mixing the cement clinker and gypsum.

  The cement clinker can be manufactured using an existing cement manufacturing facility such as an SP system (multistage cyclone preheating system) or an NSP system (multistage cyclone preheating system provided with a calcining furnace).

  Portland cement contains cement clinker and gypsum, but a smaller amount of admixture may be added. The mixed material is a blast furnace slag defined in JIS R 5211 “Blast Furnace Cement”, a siliceous mixed material defined in JIS R 5212 “Silica Cement”, fly ash defined in JIS A 6201 “Fly Ash for Concrete”, Limestone as defined in JIS R 5210 “Portland cement” can be used.

The Portland cement has a C ₃ S content of 55 to 65% by mass, a C ₂ S content of 10 to 20% by mass, a C ₃ A content of 5 to 12% by mass, and a C ₄ AF content of 5 to 12%. It is preferable that it is mass%. Also, _{C 3} S content of 57 to 60 mass%, C ₂ S content of 12 to 15 mass%, in _{C 3} A content of 8-11% by weight and _C 4 AF content of 6-10 wt% More preferably. If it is in these ranges, the manufacturing method of the blast furnace slag fine powder which can obtain the strength expression of a blast furnace cement efficiently by addition of a small amount of chlorine can be provided.

The fineness of Portland cement is preferably 2800 to 5000 cm ² / g, more preferably 3000 to 4800 cm ² / g, and further preferably 3100 to 4700. If fineness is 2800cm less than ² / g of Portland cement, it reduces the strength development of blast furnace cement, is greater than 5000 cm ² / g, increases the cost of manufacture Portland cement.

  The contents of the present invention will be described in detail below with reference to examples and comparative examples. Note that the present invention is not limited to these examples.

  In this study, the blast furnace slag is pulverized to produce fine powder of blast furnace slag, and then mixed with Portland cement to produce blast furnace cement (separated pulverization). The production method (simultaneous grinding) was used for evaluation. Tables 1 to 4 show the material characters used. Table 1 shows the chemical composition of blast furnace slag, Table 2 shows the chemical composition of chlorine bypass dust, Table 3 shows the mineral composition, chlorine content and Blaine specific surface area of Portland cement used in the separation and grinding. The mineral composition and chlorine content of the clinker used in the mixed grinding are shown. Two types of blast furnace slag with different basicities (JIS) were used, and Portland cement was manufactured by an actual machine.

The chemical component was measured using a fluorescent X-ray calibration curve obtained from an analysis result according to JIS R 5202 “Cement Chemical Analysis Method”. f. CaO was measured according to JCAS I-01: 1997 “Method for Quantifying Free Calcium Oxide” of Cement Association Standard Test Method. In addition, the mineral composition of Portland cement and Portland cement clinker is calculated from the quantified chemical components using the formulas (1) to (4) based on the C ₃ S content, C ₂ S content, C ₃ A content, and C ₄ AF content. ).

_{C 3 S = 4.07 × CaO-} 7.60 × SiO 2 -6.72 × Al 2 O 3 -1.43 × Fe 2 O 3 ··· Equation (1)
However, in the case of cement, add −2.85 × SO ₃ to the right side.

_{C 2 S = 2.87 × SiO 2} -0.75 × C 3 S ··· Equation (2)
C ₃ A = 2.65 × Al ₂ O ₃ −1.69 × Fe ₂ O ₃ Formula (3)
C ₄ AF = 3.04 × Fe ₂ O ₃ Formula (4)

Table 5 shows the materials used for the production of blast furnace slag fine powder (separation and pulverization), and Table 6 shows the composition of the blast furnace slag fine powder.
That is, the circles in Table 5 are the materials used, 95.1% by mass of blast furnace slag fine powder, 3.9% by mass of dihydrate gypsum (1.8% by mass on the basis of SO ₃ ), 1.0% by mass of limestone The chlorine bypass dust was 0 to 0.90% by mass based on 100% by mass of the total of these materials. A pulverization aid was added to these materials and pulverized with a ball mill so that the Blaine specific surface area was 4000 ± 50 cm ² / g.

*塩素バイパスダストは、高炉スラグ微粉末と二水石膏の合計量１００質量％に対して外割で添加した。

* Chlorine bypass dust was added in an external ratio with respect to 100% by mass of the total amount of blast furnace slag fine powder and dihydrate gypsum.

  Table 7 shows materials used for manufacturing (separating and grinding) blast furnace cement. That is, the ◯ marks in the table are the materials used, and were used in the blast furnace cement so that the blast furnace slag fine powder was 44.5% by mass and the Portland cement was 55.5% by mass.

  Table 8 shows materials used for manufacturing (mixing and grinding) blast furnace cement, and Table 9 shows the composition. That is, the circles in Table 8 are the materials used, 43.0% by mass of blast furnace slag fine powder, 51.8% by mass of clinker, 3.2% by mass of dihydrate gypsum, 2.0% by mass of limestone, chlorine bypass dust 0.20 to 1.00% by mass was used.

^*塩素バイパスダストは、高炉スラグ微粉末とクリンカーと石膏と石灰石の合計量１００質量％に対して外割で添加した。

^* Chlorine bypass dust was added in an external ratio with respect to 100% by mass of the total amount of blast furnace slag fine powder, clinker, gypsum and limestone.

  The mortar compressive strength was investigated using the blast furnace cement produced above. The test method was based on JIS R 5201: 1997 “Cement physical test method”, and a mortar specimen was prepared and its compressive strength was measured. In the case of separation and pulverization, no. 4 (reference) is No. in the case of mixed grinding. 8 (reference) as a reference, No. 1-3 are No.1. No. 4 compression strength ratio (%) 5-7 are No. It was expressed as a compressive strength ratio (%) to 8. Table 10 shows the results of the compression strength ratio at 7 days of age.

  FIG. 1 shows the relationship between the amount of chlorine and the compressive strength ratio of a blast furnace cement with an age of 7 days. The amount of chlorine in the blast furnace cement required to improve the strength ratio of the blast furnace cement to 100% is about 350 ppm for the separation pulverization and about 500 ppm for the mixed pulverization. The separation pulverization can improve the strength more efficiently with a small amount of chlorine. I understood.

  Therefore, according to the method for producing blast furnace slag fine powder and blast furnace cement of the present invention, it is possible to efficiently increase the strength with a small amount of added chlorine, and to produce a cement with stable quality.

Claims (7)

  Blast furnace slag fine powder, characterized in that blast furnace slag fine powder having a Cl content of 450 to 800 mg / kg is produced by simultaneously mixing and grinding blast furnace slag, gypsum, limestone, and chlorine-containing inorganic substance. Production method.   The blast furnace slag fine powder according to claim 1, wherein the blast furnace slag fine powder contains 90 to 98 mass% of the blast furnace slag, 0.5 to 5.0 mass% of the gypsum, and 0.5 to 5 mass% of the limestone. Manufacturing method. The blast furnace slag is composed of 30 to 40% by mass of SiO ₂ , 10 to 20% by mass of Al ₂ O ₃ , 30 to 50% by mass of CaO, ₃ to 10% by mass of MgO, 0.1 to Fe ₂ O ₃ . 5.0 wt%, a Na ₂ O 0.1 to 0.4 wt%, the _{K 2} O 0.2 to 0.6 wt%, the TiO ₂ 0.2 to 0.6 wt%, the MnO 0 The manufacturing method of the blast furnace slag fine powder of Claim 1 or 2 containing 0.1-0.3 mass% and 0.001-0.010 mass% of Cl. The inorganic substance containing chlorine, chlorine bypass dust is NaCl, 1 or more selected from KCl and CaCl _2, any one method of manufacturing the ground granulated blast furnace slag according to claims 1-3. SO ₃ content of blast furnace slag powder is added the plaster so that 1.0 to 2.5 wt%, any one method of manufacturing blast furnace slag as claimed in claims 1-4.   A method for producing blast furnace cement, comprising mixing 30 to 60 mass% of blast furnace slag fine powder according to any one of claims 1 to 5 and 40 to 70 mass% of Portland cement. The Portland cement has a C ₃ S content of 55 to 65% by mass, a C ₂ S content of 10 to 20% by mass, a C ₃ A content of 5 to 12% by mass, and a C ₄ AF content of 5 to 12% by mass. The method for producing a blast furnace cement according to claim 6, wherein

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