JP3428622B2 - Cement-based solidifying material and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement-based solidifying material and a method for producing the same, and more particularly to a cement-based solidifying material for reducing the production cost and expanding the use of a calcined cement raw material and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, a cement raw material is put into a suspension preheater from a chute in a cement firing facility, preheated to about 1000 ° C. by this preheater, and then supplied to a rotary kiln. Then, the cement clinker is generated by being fired in the rotary kiln with heat of about 1450 ° C.

Specifically, the cement raw material introduced into the preheater from the chute descends inside the preheater while sequentially passing through cyclones and ducts arranged in multiple stages. On the other hand, the exhaust gas heated by the high calcining heat in the rotary kiln is sucked by the induction fan,
Contrary to the cement material, it rises in the preheater and is eventually discharged to the outside of the device. Therefore, the cement raw material that has been input is gradually heated by this exhaust gas and is lowered and supplied to the cyclone at the lowest stage. Thereafter, the cement raw material passes through the chute and is introduced into the rotary kiln.

[0004]

By the way, the main materials of the cement-based solidifying material are usually Portland cement and gypsum. Of this, Portland cement accounts for the majority. As described above, Portland cement is manufactured based on the firing process of cement raw materials.
Since the firing process consumes a large amount of fuel, Portland cement is one of the factors that increase the cost. Therefore, if the calcined cement raw material before being fired in the rotary kiln can be taken out from this preheater and used as the raw material of the cement-based solidifying material, the manufacturing cost of the cement-based solidifying material should be low. .

By the way, the calcined cement raw material taken out from the preheater contains a large amount of quick lime, which causes the calcined cement raw material to not be used as a part of the cement-based solidifying material. That is, in the composition of this cement-based solidifying material, if the proportion of quick lime increases,
Although there is no problem immediately after mixing in a high temperature environment such as summer, there was a concern that the fluidity of the slurry obtained by mixing the cement-based solidifying material and water would be significantly reduced after just a few minutes to a dozen minutes. .

Therefore, as a result of earnest research, the inventor found that
As described above, by using the calcined cement raw material in the preheater as a part of Portland cement, the manufacturing cost can be reduced and the application of the calcined cement raw material is expanded. In addition, if water is added to the calcined cement raw material in advance and the quicklime contained in the calcined cement raw material is partially digested, the calcined cement raw material is relatively used as it is as a substitute for the cement-based solidifying material. The inventors have found that even if added in a large amount, it is possible to improve the decrease in the fluidity of the slurry of the cement-based solidifying material in the summer and the like, and completed the present invention.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a cement-based solidifying material which can be manufactured at a low cost and can be used for a wide range of applications of calcined cement raw materials. Another object of the present invention is to provide a cement-based solidifying material and a manufacturing method thereof that can reduce the manufacturing cost without deteriorating the quality. Further, it is an object of the present invention to provide a cement-based solidifying material capable of further increasing the fluidity of the slurry of the solidifying material and also enhancing the strength after solidification.

[0008]

According to a first aspect of the present invention, there is provided a cement-based solidifying material obtained by mixing Portland cement and gypsum, which is disposed in a cement firing facility as a part of the Portland cement. Calcination rate 80 taken out from the preheater for calcination
It is a cement-based solidifying material using a cement raw material in which the content of quick lime contained is partially digested at 90%. The proportion of Portland cement that replaces the calcined cement raw material is preferably 1 to 20%, particularly preferably 1 to 10%. If it is less than 1%, the effect of reducing the manufacturing cost becomes small. On the other hand, if it exceeds 20%, the solidification performance is lowered.

The preferable calcination rate of the calcined cement raw material is 80
% Or more. If it is less than 80%, the amount of calcium to be eluted is small, so that there is a disadvantage that the solidification performance is low. As the position of the preheater from which the calcined cement raw material having such a calcination rate of 80 to 90% can be obtained, for example, in the case of a preheater in which five cyclones are vertically assembled, it is connected to the discharge port of the first cyclone. The one taken out from the chute is preferable. The average specific surface area of the calcined cement raw material is not limited. However, it is preferably about 2000 to 4000 cm ² / g. Digestibility of quicklime in calcined cement raw material is 40%
Above, especially 50% or more is preferable. If it is less than 40%, the undigested raw coal causes the inconvenience of deterioration of fluidity.
Examples of the method for partially digesting quicklime include a method of sprinkling a predetermined amount of water in a mill that mixes Portland cement and gypsum. In addition, there is also a partial digestion method in which the calcined cement raw material is mixed with a device such as a screw conveyer and used for transporting, and water is atomized on the raw material while transporting.

The amount of Portland cement added is 80 to 9
It is about 5% by weight. Note that these values are not partially substituted for the calcined cement raw material. The average specific surface area of Portland cement is 2500-4500 cm ² /
It is about g. The addition amount of gypsum is about 5 to 20% by weight. The average specific surface area of gypsum is 3000-5000c.
It is about m ² / g.

The invention according to claim 2 is the cement-based solidifying material according to claim 1 , wherein the blast furnace slag fine powder is added in an amount of 5 to 60% by weight. If the blast furnace slag fine powder is less than 5% by weight, the production amount of ettringite, which is a cement-based initial hydrate, is not increased so much that the soil containing a large amount of organic matter cannot be solidified. Moreover, since the amount of blast furnace slag fine powder having a low initial hydration activity is smaller than that of the cement clinker, the fluidity of the slurry of the solidifying material is lowered. Further, if the blast furnace slag fine powder exceeds 60% by weight, unless the blast furnace slag fine powder has a high fineness, the ettringite that contributes to the initial strength is not sufficiently generated and the manufacturing cost increases. The average specific surface area of the blast furnace slag fine powder is about 2500 to 5500 cm ² / g.

[0012] According to a third aspect of the invention, according to claim 1 or claim 2 was added diethylene glycol 1-3 wt%
The cement-based solidifying material described in 1.

According to a fourth aspect of the present invention, in a method for producing a cement-based solidifying material, which comprises mixing Portland cement and gypsum to obtain a cement-based solidifying material, a preheater for calcination of a cement raw material in a cement calcination facility is used for calcination. Rate 80-9
0% of the calcined cement raw material is taken out, water is added to the calcined cement raw material to partially digest the quicklime in the calcined cement raw material, and the calcined cement raw material after the partial digestion is
It is a method for producing a cement-based solidifying material used as a part of the Portland cement.

[0014]

According to the invention described in claims 1 to 4 , the calcined cement raw material is used as a substitute for a part of Portland cement. The calcined cement raw material is basically a raw material of Portland cement, and its components are similar. As a result, it is possible to substitute and use the calcined cement raw material as a part of Portland cement. Actually, even if the calcined cement raw material having a calcination rate of 80 to 90% is used as a substitute, the strength of the slurry of the solidified material after solidification is
Almost the same as when using Portland cement alone. Therefore, it is possible to reduce the manufacturing cost of the cement-based solidifying material by using an inexpensive calcined cement raw material, which is a part of Portland cement. Moreover, the use of the calcined cement raw material can be expanded.

Particularly, according to the first and fourth aspects of the invention, the calcination rate from the preheater of the cement firing equipment is 80.
Remove ~ 90% calcined cement raw material and add water to it. As a result, the quicklime component contained in the calcined cement raw material is partially digested. This reaction formula is shown below. CaO + H ₂ O → Ca (OH) ₂ Then, this partially digested calcined cement raw material is used as a substitute for Portland cement. As described above, by partially digesting the quicklime, it is possible to maintain good fluidity of the slurry of the cementitious solidifying material even in the summer. This makes it possible to substitute a relatively large amount of the calcined cement raw material as a part of Portland cement. Even when the calcined lime is partially digested and the calcined cement raw material having a calcination rate of 80 to 90% is used in place of the calcined cement as a substitute, the strength of the slurry after solidification is the same as that of Portland cement alone. Almost unchanged. Therefore, it is possible to further reduce the manufacturing cost without degrading the quality.

According to the second aspect of the invention, 5 to 60% by weight of blast furnace slag fine powder is added to the cement-based solidifying material. The blast furnace slag fine powder lowers the pH of the cement-based solidifying material, suppresses elution of calcium hydroxide Ca (OH) ₂ , consumes calcium hydroxide, reacts with gypsum and Portland cement, and produces ettringite. As a result, the fluidity of the slurry of the solidifying material is enhanced, and the strength after solidification is also enhanced. In particular, the effect is remarkably exhibited in the one having a high fineness. Further, according to the invention described in claim 3 , by adding diethylene glycol, it is possible to prevent the solidified material from being dried by heat generated during digestion and causing dust generation.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. <Examples 1 to 3 and Comparative Example 1> In these Examples and Comparative Examples, cement obtained by mixing Portland cement partially substituted with calcined cement raw material and gypsum (anhydrous gypsum) at a predetermined ratio With respect to the system solidified material, the fluidity of a slurry prepared by adding water to the solidified material and kneading after 15 minutes and the 28-day-old strength were evaluated. The W / C (water / solidifying material) of the slurry is 60%. A Marsh funnel viscometer was adopted for the evaluation of fluidity, and a known uniaxial compression test method was adopted for age strength. The mixing ratio of Portland cement was 80 to 95% by weight, which was a value including a partial replacement amount with the calcined cement raw material. The mixing ratio of gypsum was 15% by weight. The calcination rate of the calcined cement raw material was 80%, and the partial digestibility of quicklime in the calcined cement raw material was 85%. For the digestion of quicklime, a method was used in which water was sprayed into the mixer when Portland cement and gypsum were mixed with the mixer during the manufacturing process of the cement-based solidifying material.

Under such conditions, the change in the fluidity of the slurry when the substitution ratio of the calcined cement raw material in Portland cement was changed was tested at room temperature of 35 ° C. assuming the summer when the temperature is high. Regarding the fluidity of the slurry, the flow time of the slurry was set to 120 (seconds) or less as appropriate (◯). Further, regarding the age strength, a 28-day-old strength of 10 kgf / m ² or more was determined to be suitable (◯). The average specific surface area of the Portland cement used was ^{3750cm 2 / g, 3000cm 2 /} g in the case of calcining cement raw material, in the case of gypsum 3800c
m ² / g. In addition, as a comparative example, a cement-based solidifying material manufactured by Mitsubishi Materials Corporation (trade name "STABILIGHT M
15 ") was used. That is, in the example, a part of the Portland cement contained in the "Stabilite M15" was used in place of the calcined cement raw material at a predetermined ratio.

The results are shown in Table 1 together with comparative examples. In addition, evaluation by manufacturing cost is also shown. For the cost evaluation, the one that is cheaper than the "Stabilite M15" was evaluated as appropriate (◯). As shown in Table 1, by using a calcined cement raw material obtained by partially digesting quicklime as a part of Portland cement, good fluidity of the solidifying material slurry can be maintained even in the summer. The calcined cement raw material can be replaced with Portland cement in a large amount, and as a result, the production cost can be reduced without deteriorating the quality. Moreover, the applications of the calcined cement raw material could be expanded.

[0020]

[Table 1]

When the same experiment was conducted by changing only the temperature condition from 35 ° C. to 20 ° C., even in the case of Comparative Example 1 in which the calcined cement raw material was not added, the fluidity of the slurry after 15 minutes passed was It was suitable (○).

<Examples 4 to 6 and Comparative Example 2> Except that the partial digestibility of quicklime was changed to the value shown in Table 2,
The experiment was conducted under the same conditions as in Example 1. As shown in Table 2, by partially digesting the quicklime in the calcined cement raw material, good fluidity of the solidifying material slurry can be maintained even in the summer, whereby a relatively large amount of calcined cement raw material can be obtained. It can be replaced as a part of Portland cement.

[0023]

[Table 2]

<Examples 7, 8 and Comparative Example 3> Experiments were carried out under the same conditions as in Example 1 except that blast furnace slag fine powder was added to the cement-based solidifying material in the amounts shown in Table 3. In addition, the flow-down time of the slurry was set to 80 seconds or less, which is more preferable (⊚). Also, the 28-day-old strength is 11 kgf.
/ M ² or more was made more preferable (⊚). As shown in Table 3, by adding the blast furnace slag fine powder, the fluidity of the slurry of the solidifying material was further increased, and the strength after solidification was further increased.

[0025]

[Table 3]

<Examples 9 and 10, Comparative Example 4> An experiment was performed under the same conditions as in Example 1 except that diethylene glycol was added to the cement-based solidifying material in an amount shown in Table 4. The slurry flow time of 80 seconds or less was more preferable (⊚). Also, the 28-day-old strength is 11k.
A value of gf / m ² or more was made more preferable (⊚). As shown in Table 4, by adding diethylene glycol, the fluidity of the slurry of the solidifying material was further increased, and the strength after solidification was further increased. In addition, the dust generation property could be improved. The dusting property was judged visually.

[0027]

[Table 4]

By the way, FIG. 1 is a graph showing the relationship between the digestibility of quicklime in the calcined cement raw material and the flow-down time of the solidifying material slurry. In the same graph, the polygonal line a indicates immediately after kneading the cement-based solidifying material and water, and the polygonal line b indicates 1 after kneading.
The state after 5 minutes is shown. As is clear from this graph, good fluidity of the slurry can be obtained immediately after kneading regardless of digestion of the quick lime, but after 15 minutes, good fluidity of the quick lime must be obtained if the quick lime is not digested. Can't get The substitution rate of the calcined cement raw material in Portland cement at this time was 10%.

[0029]

According to the inventions of claims 1 to 4 , the calcination rate from the preheater of the cement firing equipment is 80 to 9
Since 0% of the calcined cement raw material was taken out and then used as a substitute for a part of Portland cement, the manufacturing cost can be reduced and the application of the calcined cement raw material can be expanded. .

In particular, according to the inventions of claims 1 and 4, after the quick lime contained in the calcined cement raw material is partially digested, it is used as a substitute for part of Portland cement. As a result, it is possible to maintain good fluidity of the cement-based solidifying material slurry even in the summer.
As a result, the manufacturing cost can be reduced without degrading the quality.

In particular, according to the second aspect of the invention, since the cement-based solidifying material is added with the blast furnace slag fine powder in an amount of 5 to 60% by weight, the fluidity of the slurry of the solidifying material is increased and the solidifying material is solidified. Later strength can also be increased.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the digestibility of quicklime in a calcined cement raw material and the flow-down time of a solidifying material slurry according to an embodiment of the present invention.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C04B 18:14 C04B 24:02 24:02) 111: 20 111: 20 (72) Inventor Norihiro Takamiya Hachiman Nishi Ward, Kitakyushu City, Fukuoka Prefecture No. 1-1 Donan-cho Cement Development Center, Mitsubishi Materials Corporation (72) Inventor Tomoharu Oba No. 1-1 Donan-cho Cement Development Center, Hachimansai-ku, Kitakyushu, Fukuoka (56) Reference Flat 11-181424 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) C04B 7/02 C04B 7/147 C04B 7/34 C04B 7/345 C04B 7/38 C04B 28/04 C04B 28/08 C04B 28/10 C04B 28/14

Claims (4)

(57) [Claims] 1. A cement-based solidifying material obtained by mixing portland cement and gypsum, which is taken out from a preheater for calcination of a cement raw material disposed in a cement calcination facility as a part of the portland cement. A cement-based solidifying material using a cement raw material with a calcining rate of 80 to 90%, in which the contained quick lime is partially digested. 2. The cement-based solidifying material according to claim 1 , wherein the blast furnace slag fine powder is added in an amount of 5 to 60% by weight. 3. The cement-based solidifying material according to claim 1 or 2 , to which 1 to 3% by weight of diethylene glycol is added. 4. A method for producing a cement-based solidifying material, which comprises mixing Portland cement and gypsum to obtain a cement-based solidifying material, wherein a preheater for calcination of cement raw material in a cement calcination facility has a calcination rate of 80 to 90%. Take out the calcined cement raw material, add water to the calcined cement raw material to partially digest the quicklime in the calcined cement raw material, and use the calcined cement raw material after the partial digestion as a part of the Portland cement. Cement-based solidifying material manufacturing method.