JP2015009998A - Method for producing cement composition having suppressed variation of setting time - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a cement composition capable of suppressing variation of setting time by adding water washing dust even if an MgO content in a clinker changes and the setting time of a cement composition is varied.SOLUTION: Provided is a method for producing a cement composition having suppressed variation of setting time, including: a first step of measuring an MgO content in a plurality of cement clinkers; a second step of measuring an f-CaO content in water-washed dust obtained by subjecting a plurality of chlorine bypass dust to a water washing treatment; a third step of mixing the plurality of cement clinkers, the plurality of water-washed dust and gypsum, pulverizing the mixture to prepare a plurality of cement compositions, and measuring setting time thereof; a fourth step of obtaining a relational formula from the MgO content, the f-CaO content and the setting time and determining an amount of addition of the water-washed dust; and a fifth step of adding water-washed dust of an amount of addition based on the relational formula and pulverizing a mixture to prepare a cement composition.

Description

  The present invention relates to a method for producing a cement composition that can suppress fluctuations in setting time by adding washing dust even if the amount of MgO in the clinker changes and the setting time of the cement composition changes.

  The cement industry uses waste and by-products with high MgO content such as blast furnace slag as raw materials for cement clinker. However, the MgO content in the clinker fluctuates due to the difference in the raw material procurement situation between cement factories, and the setting time of the cement varies among factories (Non-patent Document 1).

  In order to suppress the fluctuation of the setting time, there is a method using a setting / curing modifier, which leads to an increase in production cost.

  On the other hand, the cement industry uses waste containing a large amount of chlorine (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 amount 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 cement. Further, as in Patent Document 3, a method has been proposed in which chlorine bypass dust is washed with water and sludge from which chlorine has been removed is added as a cement raw material.

  For this reason, it is considered that adding washing dust having a low chlorine content in the cement grinding process is an effective means. Patent Document 4 discloses that the elution of Se from cement can be reduced by adding washing dust to cement.

JP 10-330136 A JP-A-10-218657 JP2002-338312 JP2009-23903

Takayasu Ito, Yoshihiro Yamakoshi, Yuki Yumi, Relationship between the amount of alite obtained by the Rietveld method and the crystal structure and cement quality, Papers on cement and concrete, 57, pp. 2-9 (2003)

However, in the methods of Patent Documents 2 and 3, since the chlorine bypass dust has a high chlorine content, the amount added to the cement must be limited. In addition, when washing dust is added to the clinker raw material, it is necessary to reduce or change other waste unit values.
Accordingly, an object of the present invention is to provide a method for producing a cement composition that can suppress fluctuations in the setting time even if the MgO content in the clinker changes and the setting time of the cement composition changes. To do.

  As a result of intensive studies to achieve the above object, the present inventors have found that the MgO content in the clinker and the f. It has been found that there is a correlation between the CaO content and the setting time, and the present invention has been completed.

That is, the present invention relates to a first step (preliminary experiment step 1) for measuring the MgO content of a plurality of cement clinker, and f. The second step (preliminary experiment step 2) for measuring the CaO content, the plurality of cement clinker, the plurality of washing dust and gypsum are mixed and pulverized, a plurality of cement compositions are prepared, and the setting time is measured. A third step (preliminary experiment step 3), the MgO content and the f. From the CaO content and the setting time, a relational expression is obtained, and the fourth step (preliminary experiment step 4) for determining the addition amount of the washing dust to the clinker, and the cement clinker and gypsum are the first to fourth steps. The present invention relates to a method for producing a cement composition in which fluctuations in setting time are suppressed, including a fifth step (manufacturing step) in which an amount of water washing dust based on the obtained relational expression is added and pulverized to prepare a cement composition.
Moreover, the said relational expression in the said 4th process is related with the manufacturing method of the cement composition which is following formula (1) and (2).
(Starting time) = A × (f.CaO content (mass%) derived from washing dust) + B × (clinker MgO content (mass%)) + C Formula (1)
A = -60 to -10, B = 10 to 60, C = 70 to 110

(Termination time) = D × (f.CaO content (mass%) derived from washing dust) + E × (clinker MgO content (mass%)) + F Formula (2)
D = −60 to −10, E = 10 to 60, F120 to 170
However, f. CaO content = f. CaO content (mass%) × added amount of washing dust (mass%) during clinker grinding.

  ADVANTAGE OF THE INVENTION According to this invention, even if MgO content in a clinker is fluctuate | varied according to the raw material situation of a cement composition, the cement composition of the quality with the constant setting time can be provided.

F. It is the relationship between the first time calculated from the multiple regression equation which calculated | required CaO content and MgO content as an independent variable, and the first time of the measured value. F. It is the relationship between the termination time calculated from the multiple regression equation which calculated | required CaO content and MgO content as an independent variable, and the termination time of a measured value.

  The present invention is described in detail below.

In the production method according to the present invention, first, a preliminary experiment step, that is, a first step of measuring the MgO content of a plurality of cement clinker (preliminary experiment step 1), and a water washing dust obtained by washing a plurality of chlorine bypass dusts with water F. The second step (preliminary experiment step 2) for measuring the CaO content, the plurality of cement clinker, the plurality of washing dust and gypsum are mixed and pulverized, a plurality of cement compositions are prepared, and the setting time is measured. A third step (preliminary experiment step 3), the MgO content and the f. A relational expression is obtained from the CaO content and the setting time, and a fourth step (preliminary experiment step 4) for determining the addition amount of the washing dust to the clinker is performed.
Next, based on the knowledge obtained in this preliminary experimental process, the cement clinker and gypsum to be actually produced are added and pulverized with an amount of water-washing dust based on the relational expressions obtained in the first to fourth processes, and then cemented. The 5th process (manufacturing process) which prepares a composition is performed.

In the first step, the MgO content of a plurality of arbitrarily selected cement clinker is measured.
In the second step, f. In the washing dust obtained by washing with water a plurality of arbitrarily selected chlorine bypass dusts. The CaO content is measured.

In the third step, a plurality of cement clinker, a plurality of water washing dusts and gypsum are mixed and pulverized to prepare a plurality of cement compositions and the setting time is measured. That is, cement clinker with various MgO contents, gypsum and various f. Various amounts of CaO-containing washing dust are added and pulverized to prepare various cement compositions. Next, the cement composition is subjected to a setting test according to “Physical Test Method for Cement” defined in JIS R5201: 1997.
In the fourth step, the MgO content and f. The relational expression is obtained from the CaO content and the setting time, and the amount of washing dust added to the clinker is determined. The relational expression preferably takes a multiple regression analysis.

In the fifth step, the cement clinker and gypsum to be actually produced are added and pulverized with an amount of water-washing dust based on the relational expressions obtained in the first to fourth steps to produce a cement composition.
The relational expression in the fourth step is preferably the following expressions (1) and (2).
(Starting time) = A × (f.CaO content (mass%) derived from washing dust) + B × (MgO content (mass%) of clinker) + C Formula (1)
The coefficient A is −60 to −10, more preferably −55 to −15, and further preferably −50 to −20. The coefficient B is 10 to 60, more preferably 15 to 55, and still more preferably 20 to 50. The coefficient C is 70 to 110, more preferably 73 to 107, still more preferably 75 to 105.

(Termination time) = D × (f.CaO content (mass%) derived from washing dust) + E × (MgO content (mass%) of clinker) + F (2)
The coefficient D is −60 to −10, more preferably −55 to −15, and still more preferably −50 to −20. The coefficient E is 10 to 60, more preferably 15 to 55, and still more preferably 20 to 50. The coefficient F is 120 to 170, more preferably 123 to 167, and still more preferably 125 to 165.
However, f. CaO content = f. CaO content (mass%) x addition amount of washing dust during clinker grinding (mass%)

The cement clinker used in the present invention is made of limestone, quartzite, coal ash, clay using existing cement manufacturing equipment such as SP system (multistage cyclone preheating system) or NSP system (multistage cyclone preheating system equipped with a calcining furnace). A raw material selected from the group consisting of blast furnace slag, construction generated soil, sewage sludge, blast furnace dust, copper, deiron slag and incinerated ash can be mixed and fired. By using relatively large amounts of industrial waste and by-products such as coal ash and blast furnace slag, it is possible to reduce the consumption of natural resources, such as limestone and silica, and reduce energy consumption. CO ₂ emissions resulting from thermal decomposition of the fuel and combustion of the fuel can be reduced.

The mineral composition of the cement clinker has a C ₃ S content of 45 to 65% by mass, preferably 48 to 63% by mass, more preferably 50 to 60% by mass, and a C ₂ S content of 14 to 24% by mass, preferably 15-23% by mass, more preferably 16-23% by mass, C ₃ A content is 8-13% by mass, preferably 9-12% by mass, more preferably 9-11% by mass, and C ₄ AF content. It is preferable that it is 8-13 mass%, Preferably it is 9-12 mass%, More preferably, it is 9.5-11 mass%. If it is such a composition range, the fluctuation | variation of the setting time of the cement composition of this invention can be suppressed.
The MgO content in the cement clinker is 0.5 to 3% by mass, preferably 0.6 to 2.9% by mass, and more preferably 0.7 to 2.8% by mass. If the MgO content is less than 0.5% by mass, it will not be possible to contribute to the effective use of waste and by-products as clinker raw materials. If the MgO content is more than 3% by mass, strength development is reduced.

Chlorine bypass dust is dust collected from the exhaust gas extracted by the chlorine bypass device. The solid chlorine bypass dust, KCl, NaCl, consists chlorides CaCl _2, etc. and cement composition material of precalcination, their sulfates or the like. By washing the chlorine bypass dust with water, water washing dust having a low chlorine concentration can be obtained.

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 preferably used.
In the preliminary experiment process, the amount of gypsum is added so that the SO ₃ content of the cement becomes 3.5% by mass in accordance with “Cement physical test method” defined in JIS R5201: 1997.
In the fifth step of actually producing cement, the cement SO ₃ content is 1.0 to 3.5% by mass, preferably 1.5 to 3.0% by mass, more preferably 1.8 to 2.5% by mass. % Is preferred. If it is such a composition range, the fluctuation | variation of the setting time of the cement composition of this invention can be suppressed.

  In this invention, you may add a mixing material as needed. 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 fine powder can be used.

  In the present invention, chlorine bypass dust that has not been washed with water can be further added.

As a method of mixing washing dust, cement clinker, gypsum, mixed material and chlorine bypass dust, after washing water washing dust and cement clinker at the same time, mixing gypsum, mixing material, chlorine bypass dust, etc. all at the same time The method of doing is mentioned.
F. The CaO content is 1.0 to 50.0% by mass, preferably 1.5 to 47.0% by mass, and more preferably 2.0 to 45.0% by mass. If it is such a composition range, the fluctuation | variation of the setting time of the cement composition of this invention can be suppressed.
F. The CaO content is preferably 0 to 0.60 mass%, preferably 0 to 0.50 mass%, more preferably 0 to 0.45 mass%. f. If the CaO content is within this range, it is possible to suppress fluctuations in the setting time of the cement composition of the present invention. If it is such a composition range, the fluctuation | variation of the setting time of the cement composition of this invention can be suppressed.
The range in which the fluctuation of the setting time of the production method according to the present invention is more easily controlled is preferably 60 to 180 minutes for the first start, 120 to 240 minutes for the end, more preferably 80 to 160 minutes for the first start, and 140 to 140 minutes. 220 minutes. If it is these ranges, the fluctuation | variation of setting time can be suppressed more accurately.

  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.

[Preparation of cement composition]
For the preparation of the cement composition, a test ball mill was used, and the clinker, gypsum and water-washed dust after drying were ground at the same time. The amount of gypsum added was such that the SO ₃ content in the cement was 1.9% by mass, and the amount of water-washing dust added was 1.2% by mass relative to the total pulverized product. The brane specific surface area of the cement composition was 3200 ± 100 cm ² / g. For reference, a dust-free cement composition was also prepared.

Here, characters of various materials are shown. The types of clinker shown in Table 1 were used. The mineral composition of the Portland cement clinker is determined by quantifying chemical components according to JIS R 5202: 2010 “Chemical chemical analysis method”, C ₃ S content, C ₂ S content, C ₃ A content, C ₄ AF content was calculated by the following Borg equation.

_{C 3 S = 4.07 × (CaO} -f.CaO) -7.60 × SiO 2 -6.72 × Al 2 O 3 -1.43 × Fe 2 O 3
_{C 2 S = 2.87 × SiO 2} -0.75 × C 3 S
C ₃ A = 2.65 × Al ₂ O ₃ −1.69 × Fe ₂ O ₃
C ₄ AF = 3.04 × Fe ₂ O ₃

  Washing dust having f.CaO content shown in Table 2 was used. f. The CaO content was measured according to JCAS I-01: 1997 “Quantitative determination method of free calcium oxide” of the Cement Association standard test method. In addition, f.CaO content is the value of what was vacuum-dried at 20 degreeC for 6 hours, after wash-cleaning dust with acetone.

  The chemical composition of gypsum is as shown in Table 3. These chemical components were determined according to JIS R 5202: 2010 “Chemical chemical analysis method”.

  Next, a setting test was performed according to “Physical Test Method for Cement” defined in JIS R5201: 1997.

  Table 4 shows the results. F. The CaO content, the clinker MgO content and the setting time of the cement composition are shown. Based on this result, setting time as a dependent variable, f. Multiple regression analysis was performed with CaO content and MgO content as independent variables. The regression equation was obtained from equations (2) and (3).

(First departure time) = − 24.50 × (f.CaO content (mass%) derived from washing dust) + 29.09 × (clinker MgO content (mass%)) + 91.45 Formula (2)
(Termination time) = − 28.06 × (f.CaO content (mass%) derived from washing dust) + 27.55 × (clinker MgO content (mass%)) + 148.44 Formula (3)

  FIGS. 1 and 2 show the relationship between the actual setting time and the setting time (observed value) obtained using the relational expressions (2) and (3). As a result, it was found that there is a certain degree of correlation between the two. Fluctuation of condensation caused by change in MgO content is grasped and f. By calculating the CaO content, the amount of washing dust added can be calculated.

Claims (6)

A first step (preliminary experiment step 1) for measuring the MgO content of a plurality of cement clinker;
F. In washing dust obtained by washing a plurality of chlorine bypass dusts with water. A second step of measuring the CaO content (preliminary experiment step 2);
Mixing and pulverizing the plurality of cement clinker, the plurality of washing dust and gypsum, preparing a plurality of cement compositions and measuring the setting time (preliminary experiment step 3);
The MgO content and the f. A fourth step (preliminary experiment step 4) for obtaining a relational expression from the CaO content and the setting time, and determining the addition amount of the washing dust to the clinker;
Including a fifth step (manufacturing step) for preparing cement composition by adding and pulverizing the cement clinker and gypsum with an amount of water washing dust based on the relational formula obtained in the first to fourth steps. A method for producing a cement composition characterized by suppressing fluctuations in setting time. The said relational expression in the said 4th process is a manufacturing method of the cement composition which suppressed the fluctuation | variation of the setting time of Claim 1 which is following formula (1) and (2).
(Starting time) = A × (f.CaO content (mass%) derived from washing dust) + B × (clinker MgO content (mass%)) + C Formula (1)
A = -60 to -10, B = 10 to 60, C = 70 to 110
(Termination time) = D × (f.CaO content (mass%) derived from washing dust) + E × (clinker MgO content (mass%)) + F Formula (2)
D = −60 to −10, E = 10 to 60, F120 to 170
However, f. CaO content = f. CaO content (% by mass) × addition amount of washing dust (% by mass). The cement clinker has a C ₃ S content of 45 to 65% by mass, a C ₂ S content of 14 to 24% by mass, a C ₃ A content of 8 to 13% by mass, and a C ₄ AF content of 8 to 13%. The manufacturing method of the cement composition which suppressed the fluctuation | variation of the setting time of Claim 1 or 2 which is the mass%.   The manufacturing method of the cement composition which suppressed the fluctuation | variation of the setting time of any one of Claims 1-3 whose MgO content of the said cement clinker is 0.5-3 mass%.   F. From the washing dust in the cement clinker. The manufacturing method of the cement composition which suppressed the fluctuation | variation of the setting time of any one of Claims 1-4 whose CaO content is 0.6 mass% or less.   F. The manufacturing method of the cement composition which suppressed the fluctuation | variation of the setting time of any one of Claims 1-5 whose CaO content is 1-50 mass%.

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