JP2011042543A - Method for producing cement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing cement, when a cement clinker fired in a firing furnace is mixed with gypsum, and cement is pulverized by using a pulverization assistant, which can be safely used, and also, can efficiently perform the pulverization of the cement. <P>SOLUTION: When a mixture of cement clinker and gypsum is pulverized so as to produce cement, as a pulverization assistant, water-containing glycerol with concentration of 20 to 90 mass% is used at a ratio of 100 to 400 ppm as glycerol to the mixture. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a cement manufacturing method in which gypsum is mixed with a cement clinker fired in a firing furnace and pulverized to manufacture cement. More specifically, the present invention provides a method for producing a cement that efficiently grinds cement using glycerin as a grinding aid.

  In the production of cement, a cement clinker manufactured in a baking kiln such as a rotary kiln is mixed with gypsum and additives, and is pulverized to an appropriate particle size in a pulverization step to be cement. Alternatively, cement clinker, gypsum, admixture and the like are each pulverized to an appropriate particle size and then mixed appropriately to form cement.

  In the above pulverization step, as the cement pulverization proceeds, the pulverization efficiency decreases due to coating and agglomeration. Therefore, the pulverization is generally performed by adding a pulverization aid for the purpose of efficient pulverization. is there. As such grinding aids, diethylene glycol, triethanolamine, glycerin and the like are known (see Patent Documents 1 and 2 and Non-Patent Document 1). In particular, diethylene glycol is known to be excellent in cement strength (see Non-Patent Document 2).

JP-A-5-147984 Japanese Patent Laid-Open No. 11-60298

Shunji Iwabuchi, Naoto Saito, “Effect of cement grinding aid when gypsum forms are different”, Cement Technology Annual Report, Volume 20, pp. 144-148, Japan Cement Association, January 30, 1967 Yuki Ichitsubo and three others, “Effects of grinding aids on the fluidity of cement and the effects of high temperature grinding”, Cement and Concrete Technology, Vol. 59, pp. 66-73, Cement Association, February 20, 2006

  However, diethylene glycol, which is widely used as the above grinding aid, is a substance that is concerned about the safety and health effects, and as described in Non-Patent Document 2, as a grinding aid. By using diethylene glycol, it is known that a cement excellent in strength development can be obtained, while the fluidity of mortar using the cement is lowered.

  In addition, as described in Non-Patent Document 1, although glycerin has been confirmed to have an effect as a grinding aid, it is a liquid having a high viscosity at room temperature, so that it is poor in handleability and is used as a pump for supplying glycerin. There existed problems, such as the point to which an excessive load is applied and it is difficult to mix | blend glycerol with a cement clinker and a gypsum as a grinding | pulverization auxiliary agent in a predetermined compounding quantity, and to make a cement clinker and a gypsum mix | blend uniformly.

  That is, an object of the present invention is to provide a cement that can be safely used in a cement grinding process using a grinding aid and that can be efficiently ground while maintaining the quality of the resulting cement. It is in providing the manufacturing method of.

  In order to achieve the above object, the present inventors have conducted intensive research. First, paying attention to the fact that glycerin is derived from natural oils and fats and can be safely used, and as a result of investigations to reduce the viscosity of glycerin, glycerin was mixed with water and the concentration of glycerin was 90% by mass or less. It has been found that by using hydrous glycerin as a grinding aid, it can be efficiently blended into cement and the cement can be ground with high grinding efficiency.

  Furthermore, as a result of examining the use of hydrous glycerin as a cement grinding aid, the resulting cement was mixed with water by using the hydrous glycerin as a glycerin in a ratio of 100 to 400 ppm with respect to the cement clinker and gypsum mixture. As a result, it was found that the decrease in fluidity due to the grinding aid when the paste was made was completed, and the present invention was completed.

  That is, in the present invention, when a cement is produced by pulverizing a mixture of cement clinker and gypsum, hydrous glycerin having a glycerin concentration of 20 to 90% by mass or less as a pulverization aid is 100 to 400 ppm as glycerin with respect to the mixture. It is a manufacturing method of the cement characterized by using by.

  According to the present invention, cement clinker and gypsum can be obtained by using glycerin, which has been confirmed to be effective as a grinding aid, although its effect as a grinding aid has been confirmed, as a hydrous glycerin. It is possible to mix uniformly in the mixture, and as a result, it is possible to efficiently grind the cement. Furthermore, surprisingly, by using hydrous glycerin as a grinding aid, it is possible to suppress a decrease in fluidity due to the grinding aid when the resulting cement is mixed with water to make a paste. This is expected to contribute to a reduction in the amount of cement additive such as a fluidizing agent.

  The cement production method of the present invention is a hydrous glycerin having a glycerin concentration of 20 to 90% by mass as a grinding aid when a cement is produced by crushing a mixture of cement clinker and gypsum (hereinafter also referred to simply as a mixture). Is characterized by using 100 to 400 ppm as glycerin with respect to the above mixture.

(Cement clinker)
In the present invention, the cement clinker used is not particularly limited, but may be one made of a known composition, typically, the composition formula _{3CaO · SiO 2, 2CaO · SiO} 2, 3CaO · Al2O 3 , it is preferable that a main component at least one mineral selected from 4CaO _· Al2O _{3 ·} Fe2O 3. Moreover, although minerals or compounds other than these may be contained, there is no particular problem as long as the effects of the present invention are not impaired.

  Concrete examples of the cement clinker having the above composition include various types of portland cement clinker such as normal, early strength, super early strength, moderate heat and low heat, and mixed systems such as clinker for blast furnace cement and clinker for fly ash cement. A cement clinker or the like is preferably used.

  The cement clinker is obtained by firing the cement raw material in a firing furnace such as a rotary kiln. In the present invention, the cement clinker obtained by the above baking can be used as it is, but it is preferable to pre-grind the cement clinker to a certain particle size from the viewpoint of efficiently performing the grinding in the grinding step described later. The pulverizer used for the preliminary pulverization of the cement clinker is not particularly limited, and a known pulverizer for the cement clinker can be appropriately used. Examples of typical pulverizers include continuous pulverizers such as continuous tube mills and vertical roller mills, and batch-type mills such as ball mills, pot mills, and disk mills.

  The preliminary pulverization of the cement clinker may be carried out to such an extent that it can be efficiently pulverized in the pulverization step described later, and may be appropriately determined in consideration of the type and capacity of the pulverizer and the like, the processing amount of the cement clinker and the like. Usually, it is sufficient to carry out preliminary grinding so that the particle size of the cement clinker is in the range of 1 to 15 mm.

(Gypsum)
As the gypsum used in the production method of the present invention, known gypsum as a raw material for producing cement such as 2-water gypsum, half-water gypsum, and anhydrous gypsum can be used without particular limitation. A blending amount of gypsum with respect to the cement clinker is not particularly limited, and a known blending amount can be adopted. In general Portland cement, the gypsum is generally used so that the SO ₃ content in the cement is 1.5 to 4.0% by mass, preferably 1.8 to 3.0% by mass.

(Hydrous glycerin)
The cement production method of the present invention is characterized in that hydrous glycerin having a glycerin concentration of 20 to 90% by mass is used as a glycerin at a ratio of 100 to 400 ppm as a grinding aid for the above mixture. Thereby, it is possible to efficiently grind the cement while maintaining the quality of the obtained cement.

  If the glycerin concentration in the hydrated glycerin exceeds 90% by mass, the viscosity of the hydrated glycerin becomes too high, and it is difficult to uniformly mix the glycerin with the mixture at a predetermined ratio, which is not preferable. In addition, the lower the concentration of glycerin, the lower the viscosity of the hydrous glycerin. Therefore, it is preferable from the viewpoint that blending with cement is easy, and that dispersibility into cement is high and grinding can be performed efficiently. is there. However, as will be described later, when supplying the hydrated glycerin to the mixture on the means for supplying the mixture to the pulverizer such as a belt conveyor, the glycerin concentration in the hydrated glycerin is less than 20% by mass. When the water-containing glycerin is supplied to the mixture, dripping occurs and the mixture and the water-containing glycerin tend to adhere and remain on the belt conveyor or the like. In particular, it is preferable to use hydrous glycerin having a glycerin concentration of 40 to 85% by mass from the viewpoint of easy handling of hydrous glycerin. The water-containing glycerin can be used as it is, with an industrially available glycerin concentration, or further diluted with water to a predetermined glycerin concentration.

  Moreover, in the said invention, hydrous glycerol is characterized by using it in the ratio of 100-400 ppm as glycerol with respect to the said mixture. When the ratio of glycerin to the mixture is less than 100 ppm, the effect of improving the grindability of cement cannot be obtained sufficiently, which is not preferable. Moreover, when the ratio of the said glycerol exceeds 400 ppm, since it exists in the tendency for the fluidity | liquidity of the cement paste obtained by mixing the cement after grinding | pulverization with water, it is unpreferable. In particular, it is preferable to use the glycerin at a ratio of 150 to 300 ppm with respect to the mixture from the viewpoint of the grinding efficiency of the cement and the fluidity of the cement paste.

(Method for supplying hydrous glycerin)
In the present invention, the method for supplying the hydrated glycerin to the mixture at the time of pulverization is not particularly limited, taking into account the cement production equipment, the type of pulverizer described later, the throughput of the mixture to be pulverized, and the like. What is necessary is just to determine suitably.

  As the supply method, on the supply means for supplying the mixture to a crusher such as a belt conveyor, a cement clinker and gypsum are sequentially supplied at a predetermined ratio to prepare a mixture, and then from a supply nozzle installed on the supply means. Grinding while supplying water-containing glycerin to the mixture at a predetermined ratio and continuously supplying the mixture and water-containing glycerin to the pulverizer, and supplying cement clinker and gypsum continuously at a predetermined ratio to the pulverizer A continuous supply method such as a method of continuously supplying hydrated glycerin from a supply nozzle installed in the machine, or a pulverizer after supplying cement clinker, gypsum and hydrated glycerin to the pulverizer at a predetermined ratio. A batch type supply method can be mentioned.

  Among the above-described methods, the supply of hydrous glycerin is continuously performed by a supply means for supplying the mixture to the pulverizer or a supply nozzle installed in the pulverizer because it can be pulverized continuously. A continuous supply method is preferable.

  Furthermore, it is also possible to add an inorganic mixed material such as limestone, blast furnace slag or fly ash at the time of pulverization and pulverize simultaneously. Among the above-described methods, the supply of hydrous glycerin is continuously performed by a supply means for supplying the mixture to the pulverizer or a supply nozzle installed in the pulverizer because it can be pulverized continuously. A continuous supply method is preferable.

  The diameter of the supply nozzle for supplying the hydrated glycerin may be appropriately determined in consideration of the processing amount of the mixture to be pulverized, the glycerin concentration in the hydrated glycerin, and the range of 5 to 15 mm is usually sufficient. . Moreover, the supply form of the water-containing glycerin from a supply nozzle will not be restrict | limited especially if a water-containing glycerin can be supplied to the said mixture in a predetermined | prescribed ratio, All of dripping, spraying, and a continuous flow are possible. However, when supplying hydrous glycerin, the supply nozzle is blocked by dust generated by contact with the mixture or fine cement powder generated in the pulverizer, so that hydrous glycerin can be supplied stably and continuously. It may disappear. Therefore, it is particularly preferable to supply the hydrated glycerin discharged from the supply nozzle in a continuous flow from the viewpoint of preventing the nozzle from being blocked by fine powder. The length of the continuous flow of hydrous glycerin supplied from the nozzle may be such that the nozzle is not clogged, and it is sufficient if the continuous flow is about 10 cm or more from the discharge port of the normal supply nozzle.

(Milling the mixture)
In the present invention, the pulverizer used for pulverizing the mixture of cement clinker and gypsum is not particularly limited, and any known pulverizer used in cement production facilities can be used as appropriate. Examples of typical pulverizers include continuous pulverizers such as continuous tube mills and vertical roller mills, and batch-type mills such as ball mills, pot mills, and disk mills.

The pulverization conditions for the mixture in the present invention are not particularly limited, and may be appropriately determined in consideration of the size of the pulverizer, the amount of the mixture used for pulverization, the particle size of the resulting cement, and the like. For example, when producing ordinary Portland cement, pulverization is generally performed so that the Blaine specific surface area is in the range of 2500 to 5000 m ² / g.

  Further, the temperature at which the mixture is pulverized is not particularly limited as long as it does not affect the quality of the cement to be obtained, and may be appropriately determined in consideration of the ability of the pulverizer and the temperature of the cement clinker in the mixture. . The temperature at which the mixture is pulverized is generally in the range of 10 to 150 ° C., although it depends on the pulverizer. In the cement production method of the present invention, the viscosity of the hydrous glycerin tends to decrease as the temperature increases. Therefore, the higher the temperature during pulverization, the better the dispersibility of the hydrous glycerin into the cement and the better the grinding efficiency. There is a tendency. Therefore, it is particularly preferable that the temperature during pulverization is appropriately determined within a range of 100 to 150 ° C.

  As described above, according to the present invention, by using water-containing glycerin having a glycerin concentration in a predetermined range as a grinding aid in a ratio of 100 to 400 ppm as glycerin with respect to a mixture of cement clinker and gypsum, It is possible to pulverize the cement efficiently. Moreover, since glycerin is a safe drug derived from a natural oil / fat component, the method for producing a cement according to the present invention is a production method that is highly safe at the time of pulverizing the cement and has a low environmental impact.

  EXAMPLES Examples will be shown below for specifically explaining the present invention, but the present invention is not limited to these examples.

Example 1
Ordinary Portland cement clinker (hereinafter, also simply referred to as “clinker”) was taken out from a great cooler installed in front of the kiln of the rotary kiln for firing, and coarsely pulverized to less than about 5 mm with a jaw crusher to obtain a coarse powder clinker. A predetermined amount of 2-water gypsum (2% by mass in terms of SO _{3 with} respect to the clinker) was added to 2 kg of the coarse powder clinker to prepare a mixture.

To the above mixture, 230 ppm of hydrous glycerin having a glycerin concentration of 85% by mass (196 ppm in terms of glycerin with respect to the mixture) was added as a grinding aid, and the brain specific surface area was 3100 cm ² / g in a pot mill having an internal volume of about 10 L Trial cement was obtained by grinding to ± 50 cm ² / g). The fluidity of the obtained cement was evaluated by measuring paste flow. The results are shown in Table 1. The paste flow was measured according to JASS 15 M-103 (quality level of self-leveling material), and the fluidity was evaluated by the flow value of the paste. The paste was prepared by kneading with a Hobart mixer for 3 minutes, with a water-solid ratio of 0.3 (mass ratio) and an addition amount of high-performance AE water reducing agent of 1.5% of the solid mass. The flow value of the paste was measured 10 minutes after water injection.

The pulverization was confirmed by measuring the time from the start of pulverization by the pot mill until the brane specific surface area of the cement reached 3100 cm ² / g.

Examples 2-4
Cement was pulverized in the same manner as in Example 1 except that hydrous glycerin was added in the amount shown in Table 1. The results are shown in Table 1. The grindability is shown as a relative ratio when the time required for grinding in Example 1 is 100.

Comparative Examples 1-2
Cement was pulverized in the same manner as in Example 1 except that the amount of glycerin in 85% aqueous solution was changed to the addition amount shown in Table 1. The results are shown in Table 1. The grindability is shown as a relative ratio when the time required for grinding in Example 1 is 100.

Examples 5-6
Cement was pulverized in the same manner as in Example 1 except that the glycerin concentration in the hydrous glycerin was adjusted to the concentration shown in Table 2, and the hydrous glycerin was added to the mixture so as to be 196 ppm in terms of glycerin. The results are shown in Table 2.

Example 7
Cement clinker is transported at a feeding speed of about 100 t / h by a belt conveyor, and during transportation, gypsum and hydrous glycerin having a glycerin concentration of 85% by mass are sequentially added, and then supplied to a continuous tube mill for powder. Grinding was carried out until the degree was 3500 cm 2 / g as a brane value. In addition, gypsum was added so that it might become 2 mass% in conversion of SO3 with respect to cement clinker. Moreover, the hydrous glycerin was added so that it might become 230 ppm as glycerin with respect to cement from the nozzle of 8 mm in diameter installed in the height of 30 cm from the belt of a belt conveyor. At this time, the hydrated glycerin could be supplied in a continuous flow from the nozzle to the cement on the belt conveyor, and problems such as adhesion to the belt and nozzle clogging did not occur.

Claims (4)

In producing cement by pulverizing a mixture of cement clinker and gypsum, hydrous glycerin having a glycerin concentration of 20 to 90% by mass is used as a glycerin in a proportion of 100 to 400 ppm as glycerin with respect to the above mixture. Cement manufacturing method. The method for producing a cement according to claim 1, wherein the glycerin concentration in the hydrous glycerin is 40 to 85 mass%. The manufacturing method of the cement of Claim 1 or 2 which uses 150-300 ppm of hydrous glycerin as glycerin with respect to the said mixture. The water-containing glycerin is supplied by continuously supplying water-containing glycerin from the nozzle by a supply means for supplying the mixture to the pulverizer, or a supply nozzle installed in the pulverizer. 4. The method for producing cement according to any one of items 3 to 3.