JP2776018B2 - Manufacturing method of cement - Google Patents

Description

The present invention relates to a method for producing cement, and particularly to mortar or concrete (hereinafter, concrete will be described as an example).
The present invention relates to a production method effective for improving the effect of a dispersant added to improve the fluidity of concrete at the time of kneading.

[Conventional technology]

If the amount of water in the uncured concrete is large, it is easy to cast because the fluidity of the concrete is large, but the strength after curing is small, so it is necessary to knead with a small amount of water as much as possible, In general, a water reducing agent is used in order to obtain a small amount of kneading water.

Tricalcium silicate (C
₃ S), dicalcium silicate (C ₂ S), tricalcium aluminate (C ₃ A),
It contains iron and tetracalcium lime (C ₄ AF), etc. Of these, C ₃ A and C ₄ AF have a high hydration rate, and are added to C ₃ S and C ₂ S when pouring and kneading concrete. Prior to hydration, a hydration product was formed, and this product adsorbed the water reducing agent, thereby reducing the effect of the water reducing agent.

In order to reduce the above-mentioned effects of C ₃ A and C ₄ AF, the following methods have conventionally been used.

The raw materials are mixed so that the content of C ₃ A and C ₄ AF in the cement is reduced.

Coarse cement fines reduce the formation of fines rich in C ₃ A and C ₄ AF.

Cement was added a large sulfate dissolution rate such as sulfuric acid alkali, to produce ettringite _{(C 3 A · 3CaSO 4 ·} 31H 2 O) to C ₃ A and C ₄ surface of the AF immediately after injection and kneading, C ₃ Inhibits hydration of A and C ₄ AF.

 However, these methods have the following problems.

In the method (1), the ease of burning of the cement clinker deteriorates, the amount of fuel used increases, and the initial strength of the cement deteriorates.

 In the method (1), the strength development of the cement is deteriorated.

In this method, only a sulfate having an extremely high dissolution rate can be used, and a small amount of about 0.3 part by weight of SO ₃ is used per 100 parts by weight of cement, so that the supply method is difficult.

[Problems to be solved by the invention]

The present invention has been developed to solve the above-mentioned problems of the prior art.
An object of the present invention is to provide a method for producing a cement capable of improving the effect of a water reducing agent added at the time of kneading concrete.

[Means for solving the problem]

In order to solve the above-mentioned problems, the present invention provides a method of pulverizing clinker into cement and / or transporting the cement to a storage tank by adding 100 parts by weight of the cement to the cement.
An object of the present invention is to provide a method for producing cement, which comprises spraying and mixing 0.02 to 1.0 parts by weight of sulfate as O ₄ as an aqueous solution.

[Action]

Various portland cements and mixed cements are used as the cement in the method of the present invention.

In the present invention, the aqueous solution containing a sulfate is, for example, a pulverizer (finishing mill) for pulverizing clinker into cement.
In the inside of the fine powder transport screw conveyor provided under the separator that classifies the crushed powder as fine powder (cement), receiving cement from the screw conveyor,
This is sprayed on a belt conveyor for transporting it to a storage tank (silo) or a combination thereof to be mixed with cement. The temperature of the cement at the above application / mixing point is 60
Because the temperature is above ℃, the water in the aqueous solution evaporates immediately and completely,
The cement does not solidify due to moisture during storage.

Any sulfate can be used as long as it is soluble in water, but it has high solubility and relatively inexpensive MgSO ₄ , FeSO
_{4, Na 2 SO 4, K} 2 SO 4, NaHSO 4, KHSO 4, (NH 4) 2 SO 4, Al 2 (SO 4)
Sulfates _{6 such, Na 2 SO 4 · Al 2} (SO 4) 3 · 24H 2 O, (NH 4) 2
_{SO 4 · Fe 2 (SO 4} ) 3 · 24H 2 O and the like alum are suitably used. This sulfates such is directly reacted with C ₃ A and C ₄ AF in the cement, C ₃ A and C ₄ surface ettringite (above) of the AF or monosulfate _{(C 3 A · CaSO 4 ·} 11H 2 O ) To cover the surface and inhibit C ₃ A and C ₄ AF from reacting with water to form hydration products, thereby reducing adsorption of water reducing agents to hydration products, The fluidity of concrete improves.

Spraying and mixing amount of sulfate, 100 parts by weight of cement relative to the 0.02 to 1.0% by weight as SO _4. If it is less than 0.02, the effect is not sufficient, and if it exceeds 1.0% by weight, the effect is not enhanced, and it is preferably 0.1 to 0.5% by weight.

The amount of water used for dissolving the sulfate is not particularly limited, and preparation of an aqueous solution and spraying / mixing operation,
Taking into account the complete evaporation of water due to the temperature of the cement at the time of spraying and mixing, the amount is about 0.3 to 1.5 parts by weight with respect to 100 parts by weight of the cement.

A spray or the like is appropriately used for spraying and mixing the aqueous solution.

〔Example〕

Example 1 An aqueous solution of magnesium sulfate shown in Table 1 was sprinkled from a clinker supply side into a finishing mill producing ordinary Portland cement, mixed with the cement, and a concrete test was performed at 20 ° C using the obtained cement. Was done.

The blend per concrete 1 m ³ is cement 400k
g, water 110 kg, fine sand 77 kg, coarse sand 689 kg, crushed stone 1151 kg, and the amount of water reducing agent (Mighty 150) added to cement weight is 1.6
%.

The test results are shown in Table 1. The steam curing condition was maintained at a temperature of 70 ° C. for 3 hours, and the autoclave curing condition was maintained at a temperature of 185 ° C. for 4 hours.

By sprinkling and mixing the aqueous solution of magnesium sulfate, slump appearance of the concrete was improved and slump loss was reduced. Therefore, if the concrete is kneaded with a constant slump, the kneading water can be reduced, and the strength of the concrete can be increased.

Example 2 An aqueous solution of sodium sulfate (Na ₂ SO ₄ ) shown in Table ₂ was sprayed and mixed into a screw conveyor for transporting fine powder (cement) under a separator of a finishing mill for producing ordinary Portland cement. A concrete test was performed using the obtained cement. The conditions for the concrete test were the same as in Example 1.

 The test results are shown in Table 2.

As in Example 1, the slump appearance was good and the slump loss was small.

[Effects of the Invention] The fluidity of concrete kneaded under the same conditions is improved by the method for producing cement according to the present invention, as compared with the case where conventional cement is used.

Since the amount of water and the amount of the water reducing agent used can be reduced to obtain the same fluidity as the concrete using the conventional cement, the strength development of the concrete is improved and the manufacturing cost is reduced.

Continuation of the front page (72) Inventor Yasuhiro Fukada 1-297 Kitabukuro-cho, Omiya-shi, Saitama Mitsui Mining & Cement Co., Ltd. Central Research Laboratory (56) References JP 50-50116 (JP, A) (58) Survey Field (Int.Cl. ⁶ , DB name) C04B 7/52 C04B 22/14

Claims (1)

(57) [Claims] In a pulverizing step of pulverizing a clinker into cement and / or a transporting step of transporting the cement to a storage tank, an aqueous solution containing 0.02 to 1.0 parts by weight of sulfate as SO _{4 in} 100 parts by weight of the cement. A method for producing cement, characterized by being sprayed and mixed as a mixture.