JP3027593B2 - Manufacturing method of special cement - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a special cement having excellent thermal stability and a special cement using the special cement selected by the method.

[Prior Art] Conventionally, it is well known that steel slag is effectively used for cement because of its potential hydraulic property, and a typical example is cement using blast furnace slag.

On the other hand, the use of steelmaking slag is also known, and slag cement of a specific composition has been proposed (Japanese Patent Publication No. 57-34227).
No.).

Further, in JP-A-57-129849, γ-2Cao · SiO ₂
And one or a 12CaO · 7A of 3CaO · 2SiO ₂ · CaF ₂
Disclosed is a cement comprising a blend of gypsum with a specific ratio of a solid solution of ₂ O ₃ and CaF ₂ to a steelmaking electric furnace path reducing phase slag.

There is also a proposal of a cement in which gypsum and slaked lime are mixed with steelmaking slag (Japanese Patent Publication No. 51-45536).

Further, Japanese Patent Application Laid-Open No. 63-1666739 discloses that steelmaking slag powder having a small amount of alkali and boron components is used as cement.

[Problems to be Solved by the Invention] Cement containing iron and steel slag as a main component does not pose a practical problem from the viewpoint of reproducibility if it has a large and stable slag composition such as blast furnace slag. In furnace steelmaking slag, since the slag composition always changes subtly and the cooling rate and atmosphere also differ, it is very problematic to find reproducibility when using it for cement.

The above-mentioned JP-A-63-1666739 is a steelmaking slag according to the development of the present inventors, unlike ordinary cement,
Although the present inventors have developed a unique cement with heat stability, there is a problem of refractory material erosion due to melting operation with an electric furnace for industrial use, and it is not necessarily from the viewpoint of energy cost. This is not an advantageous method.

In view of the above problems, the present inventors have clarified the composition based on a number of experiments from various viewpoints in order to develop a thermally stable cement by a firing method. Successful development of a special cement that can be used.

[Means for Solving the Problems] That is, the method for producing a special cement of the present invention has the following characteristic chemical composition: CaO = 40.0 to 65.0% by weight, SiO ₂ = 10.0 to 32.
0% by weight, A ₂ O ₃ = 7.0 to 24.0% by weight, F = 1.5 to 12.0% by weight and other components are within 15% by weight or less. The chemical composition of the following formula (weight ratio) ( A), (B)
And satisfy (C): The mineral composition determined by powder X-ray diffraction
_{O · 7A 2 O 3 · CaF} 2, β-2CaO · SiO 2, γ-2CaO · at least two hydraulic component of SiO ₂ was selected and 3CaO · 2SiO ₂
・ Has at least one kind of stable mineral selected from CaF ₂ and CaF ₂ ; fineness is 2000 to 5000 cm ² / g by Blaine specific surface area measurement
In the method for producing special cement, which is within the range of Ca
Raw materials selected from O raw materials, SiO ₂ raw materials, A ₂ O ₃ raw materials and F raw materials or steelmaking slag, blast furnace slag, and alloy production slag are fired in a temperature range of 1000 to 1200 ° C., cooled, coarsely crushed and finely ground. It is characterized by crushing.

Further, the special cement according to the present invention is characterized in that active silica is blended with the special cement produced by the above-mentioned special cement production method in an amount of 5 to 35% by weight based on the total weight.

 Hereinafter, the special cement of the present invention will be further described.

The method for producing a special cement according to the present invention is a method for producing a pulverized product after firing and cooling having the above four physicochemical properties, blending desired raw materials, firing in a temperature range of 1000 to 1200 ° C, and cooling. Crushing and pulverizing.

Although special cements obtained by the production method according to the present invention are those having the chemical composition of as described above, particularly preferably CaO = 42-60 wt%, SiO ₂ = 10 to 30 wt%, A ₂ O ₃
= 10 to 22% by weight, F = 4 to 12% by weight and other components
15% by weight or less.

In addition, as other components, there are unavoidable components which may be mixed in from the erosion of the raw material system and the refractory of the firing furnace or intentionally mixed in order to protect the erosion of the refractory and components which can be optionally added. The unavoidable components include, for example, MgO components and Fe ₂ O ₃ components.

In addition, boron, phosphorus, vanadium,
One or more components, such as sodium, potassium, barium or strontium, can be contained as oxides up to at most 2% by weight.

Especially boron component preferably, B up to 2 wt% most as ₂ O _3, it is preferable that normally contains in the range of 0.2 to 1 wt%. This is because if a large amount of B ₂ O ₃ is added, 11CaO ・ 7A ₂
O ₃ .CaF ₂ cannot be precipitated, and 2CaO.A ₂ O ₃ .SiO ₂ precipitates, which causes a problem in hydraulic performance.

Further, such a chemical composition is required to satisfy the above composition formulas (A), (B) and (C). The composition formulas (A) and (B) are so-called basicity formulas, and the composition formula (C) defines an acceptable range as a special cement, and both were set by a number of experiments together with the chemical composition. This is a necessary condition.

Outside this range, hydraulic and / or thermal stability is insufficient, and a special cement having both practical hydraulic strength and heat resistance up to around 1000 ° C. cannot be obtained with good reproducibility.

Further, it is a sufficient condition that the special cement obtained by the production method according to the present invention is a crystal particle powder having a hydraulic mineral as a hydraulic crystal phase and a stable mineral as a non-hydraulic crystal phase as described above. I have.

In such crystal particle powder, the content ratio of the hydraulic mineral component varies within the range of an acceptable chemical composition, but is in the range of 5 to 90% by weight, preferably 10 to 75% by weight.

The reason for this is that if the hydraulic mineral component is less than about 5% by weight, practical hydraulic strength cannot be obtained, while if it exceeds about 90% by weight, the cement-cured molded article will crack when heated. ) And distortion (warpage), and the shrinkage rate increases, resulting in deterioration of strength and the like, resulting in loss of thermal stability.

Further, in the above crystalline particle powder, 11CaO.7A ₂ O ₃
The content ratio of at least two hydraulic minerals selected from CaF ₂ , β-2CaO.SiO ₂ or γ-2CaO.SiO ₂ is not particularly limited.

In the present invention, because _{11CaO · 7A 2 O 3 · CaF} 2 is,
Are very close to the diffraction lines of the X-ray diffraction on the 12CaO · 7A ₂ O _3, may be regarded as CaF ₂ was dissolved in the crystal.

Moreover, as can be seen from the water hardness components, one hydraulic component of 3CaO · SiO ₂ is that contained no features of special cements obtained by the production method according to the present invention having the usual cement such as Portland cement It is one.

Next, in the present invention, the stable mineral is a crystal phase component substantially unrelated to the hydraulic reaction,
2SiO refers to ₂ · CaF ₂ and at least one or more crystalline phases selected from CaF _2, it is preferable that CaF ₂ is present.

Furthermore, in the case where MgO component is inevitably contained, in addition to the above, MgO, further 3CaO · MgO · 2SiO _2, 5Ca
_{O · MgO · 3SiO 2, 2CaO} · MgO · SiO 2 and MgO · A ₂ O ₃ or the like of the two-component or may be a ternary one or two or more of magnesium-based crystalline phase contains.

These stable mineral components impart thermal stability to the special cement obtained by the production method according to the present invention, and are contained in the range of 10 to 95% by weight as described above.

As described above, the special cement obtained by the production method according to the present invention has a completely different cement composition from the conventional Portland cement, early-strength cement, ultra-high-strength cement, alumina cement and the like.

In the present invention, each of the above mineral compositions and their ratios is identified based on the powder X-ray diffraction measurement method, and the ratio (R%) of each composition is expressed by the following formula: [Where Hs is the measured count of the first peak of each identified mineral (cps) and H is the measured count of the first peak of the target mineral]. is there.

Therefore, for example, 5 to 90% by weight of hydraulic mineral Wherein, Hss measuring count of the first peak of the stable minerals (cps), H ₁ is _{11CaO · 7A 2 O 3 · CaF} 2 or 12CaO · 7A
The count number (cps) of the first peak of ₂ O ₃ , H ₂ is β-2CaO
· Represents the count number (cps) of the first peak of SiO ₂ or γ-2CaO · SiO ₂ ].

Furthermore, the special cement obtained by the production method according to the present invention must have a Blaine specific surface area of 2000 to 5000 cm ² / g and a fineness. The reason for this is that if it is less than about 2000 cm ² / g, the hydraulic reaction is insufficient and the initial strength is not obtained, so that it lacks practicality, while the upper limit is set practically for the convenience of grinding. It is a thing.

When the special cement obtained by the production method according to the present invention is mass-produced as having a stable quality, it is preferable to mix desired raw materials and synthesize them.

That is, a raw material having a composite of various components such as CaO raw material, SiO ₂ raw material, A ₂ O ₃ raw material and F raw material or steelmaking slag (oxidation stage slag, reduction stage slag), blast furnace slag, alloy production slag, etc. Desired raw materials are blended so that the composition of the fired product falls within the above range, and firing is performed in a heating furnace. Examples of the heating furnace include a roller kiln, a shuttle kiln, and a tunnel kiln, in addition to a cement kiln.

The firing is performed at about 1000 ° C. to 1200 ° C. After the firing, it is taken out of the furnace and cooled by air to be crystallized. However, when boron or the like is added, the step of air cooling can be omitted. If the firing temperature is outside this range, it will be difficult to obtain an appropriate cement composition. The calcined product can be commercialized by cooling to room temperature and then coarsely and finely pulverized.

Although the components and proportions of the crystal phase in the product mainly depend on the composition of the raw material mixture, it also depends on the heating and cooling conditions. Obtainable.

In using the special cement obtained by the production method according to the present invention, not to mention the use of the cement itself, but in many cases, by using it in combination with the activated silica, the characteristic result function can be more exerted. .

The amount of activated silica varies depending on the purpose of use and the physical properties of the cement, but in most cases SiO ₂
5 to 35% by weight, preferably 10 to 25% by weight.

Here, activated silica refers to fine silica that causes a neutralization reaction of a base component such as CaO in cement in the presence of water and under a heated state, for example, ferrosilicon dust,
Examples thereof include fumed silica, silica sol and activated clay, and particularly, ultrafine silica such as ferrocillin condust and fumed silica is preferable.

Further, in producing an inorganic molded article having a desired shape or size using this cement as a binder, the aggregate to be used is not particularly limited, but if fire resistance and heat resistance are desired, , Especially those subjected to heat history, such as chamotte, refractory brick waste, various ceramic waste,
Slowly cooled slag or igneous rock at the time of refining various metals is preferable.

Special cement obtained by the production method according to [work for the present invention, the a ground product after firing cooling having a specific chemical composition _{as, 11CaO · 7A 2 O 3 ·} CaF 2 (12CaO · 7A
_{2 O 3), β-2CaO} · SiO 2 or gamma-2CaO · a SiO ₂ of two or more species selected hydraulic mineral component and 3CaO · 2SiO ₂ · CaF ₂ and at least one or more selected from CaF ₂ It has a stable mineral as a crystalline phase. _{Thus, 11CaO · 7Al 2 O · CaF} 2 by hydraulic reaction at room temperature, to form calcium aluminate based hydrated, imparts early strength. Also, β-2CaO.
Most of SiO ₂ or γ-2CaO.SiO ₂ exists as an unhydrated crystal phase, but the hydration reaction proceeds gradually, and the long-term strength is increased. In addition, the cement according to the present invention has a property of sufficiently functioning in a place where the W / C is small as compared with ordinary cement. Furthermore, this cement is used as a binder for fire resistance,
In the case of adding active silica for the purpose of obtaining a heat-resistant inorganic moldings is related to the amount, _{but, 11CaO · 7A 2 O 3 ·} Ca
F ₂ is hydraulically hardened by the same hydration reaction as described above. In the presence of activated silica, calcium aluminate hydrate
To _{2CaO · A 2 O 3 · SiO} 2 in such CaO-A ₂ O ₃ -SiO ₂ based mineral, β-2CaO · SiO ₂ or γ-2CaO · SiO ₂ is 3CaO · 2SiO
₂ · changes CaF such CaO-SiO ₂ -CaF to ₂ based minerals, thermal stability is imparted.

The cement according to the present invention is a unique cement having both hydraulic properties and heat resistance and exhibits a binding action of various aggregates.

[Implementation example Example 1-7 (1) Preparation of a special cement limestone, bauxite, fluorspar, blast furnace slag, ferronickel slag, silica rock, industrial chemicals, and alkali glass (B ₂ O ₃ = 31 wt Borosilicate %) And then crushed.
After collecting the vulcanized products with a 5 mm sieve, then, using various ground samples as raw materials, 10 kg of each compound is fired at 1000 to 1100 ° C. for 3 hours using a 72 kW external heating resistance electric furnace, and then cooled to obtain a fired material. Obtained.

Next, the obtained fired product was pulverized with a ball mill to obtain various special cements. When the physical properties of this special cement were measured, the results shown in Tables 1 and 2 were obtained.

(2) Evaluation 2. Preparation of molded article (specimen) The special cement obtained in each example was used as a binder, and the aggregated chamotte powder (composition and particle size) was added thereto in a mixing ratio as shown in Table 3. Table 4 below), silica flower [SiO ₂ = 90% by weight: manufactured by Nippon Heavy Industries, Ltd.], a water reducing agent and water, and a flow value of about 200 m
The mixture was kneaded with a mortar kneader having a ball capacity of 5 according to ASTM standard so as to obtain m.

Next, it is poured into a 160 mm × 450 mm × 10 mm formwork, is subjected to vibration molding, is left in a constant temperature and humidity room at 20 ° C. and 80% RH for 24 hours, and is then removed from the mold. 6 in a constant humidity room
Air-dried curing was performed for days. Next, each molded body after air-drying curing was cut with a cutter, nine specimens of 160 mm × 40 mm × 10 mm (thickness) were prepared for each sample, and three sets of three specimens were prepared. Created.

b. Curing conditions of test specimens Two sets of three specimens of one sample are 850 ° C by electric furnace.
Alternatively, heat at a maximum temperature of 1050 ° C. for 60 minutes, take out at 300 ° C., allow to cool naturally, and use it as a specimen for physical property measurement.

The remaining one set is used as a test specimen without heat treatment.

c. Evaluation method of test specimen (1) "Bending strength" shall be measured at a span of 100 mm, a center load, and a constant displacement load = 0.5 mm / min. The numerical values are average values of three specimens per set of one sample.

(2) The "shrinkage ratio" is the same as that of the same specimen (160mm x 40mm x 10mm thickness) after air drying and curing at 850 ℃ and 1050 ℃.
After heating and cooling, measurement was made using a caliper, and the dimensional change was expressed as a percentage with the dimension after air-drying curing as 100. The numerical values are the average value of a set of three as in the above item (1).

(3) “Warping” was measured for the heated specimen, and the “bending warpage” and “bending” due to heating were measured in accordance with JIS A-5209 “Ceramic tiles” using the plane in contact with the mold as the measurement surface. .

In addition, the sign of (+) was attached to the measured value for “bent warpage” and the sign of (−) for “bump warpage”. The numerical values are the average value of one set of three as in the above items (1) and (2).

(4) “Crack” is visually measured with the naked eye.

d. Evaluation results The physical properties of each specimen obtained above were measured.
The results in the table were obtained.

As can be seen from the above results, the air-dried cured specimens all have a flexural strength of 60 kgf / cm ² or more.

In addition, when this cement is used in combination with activated silica, the bending strength of all specimens heated at 850 ° C exceeds that of the air-cured cured product, and even when heated at 1050 ° C, the strength deteriorates almost completely. Not.

In addition, cracks are not substantially observed against a severe thermal change from room temperature to 1050 ° C., and the shrinkage is within 1.0% and the warpage is extremely small.

Examples 8 to 14 (1) Preparation of special cements When the special cements of Examples 1 to 7 are manufactured in a 72 kW electric furnace, heating and firing are performed in the same manner as in Example 1 without adding alkali borosilicate glass. Created things.

Most of the obtained sinter was powdered and collapsed in Examples 8 and 9, and the sinters of Examples 10, 11, 12, 13, and 14 were not powdered but solidified in a lump. These sintered products were prepared in Example 1.
A special cement was prepared by pulverization in the same manner as described above. The physical properties of this special cement were measured.
The results in the table were obtained.

(2) Evaluation and Conclusion Each of the cements obtained in Examples 8 to 14 was mixed in a proportion of 3 shown in Table 3 under the same operating conditions as in Example 1 to obtain 1 mixture.
A set of specimens was prepared.

After curing this sample under the same operating conditions as in Example 1, the physical properties were evaluated. The results in Table 9 were obtained.

Test No. in Table 9 is a specimen using cement corresponding to Example No.

Comparative Example Using ordinary Portland cement, a set of three specimens was prepared for the compounds shown in Table 10 under the same operating conditions as in Example 1.

After curing the specimen under the same operating conditions as in Example 1, the physical properties were evaluated. The results shown in Table 11 were obtained.

[Effect of the Invention] When a special cement obtained by the production method according to the present invention and active silica are used in combination, unlike a conventional Portland cement, an inorganic binder having remarkable thermal stability and thermal shock resistance is used. Become.

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-2-164749 (JP, A) JP-A-2-164750 (JP, A) JP-A-57-129849 (JP, A) (58) Investigation Field (Int.Cl. ⁷ , DB name) C04B 7 / 345,7 / 147 C04B 28 / 08,22: 06

Claims (3)

(57) [Claims] 1. The following chemical composition: CaO = 40.0-65.0% by weight, SiO ₂ = 10.0-32.
0% by weight, A ₂ O ₃ = 7.0 to 24.0% by weight, F = 1.5 to 12.0% by weight and other components are within 15% by weight or less. The chemical composition of the following formula (weight ratio) ( A), (B)
And satisfy (C): The mineral composition determined by powder X-ray diffraction
_{O · 7A 2 O 3 · CaF} 2, β-2CaO · SiO 2, γ-2CaO · at least two hydraulic component of SiO ₂ was selected and 3CaO · 2SiO ₂
・ Has at least one kind of stable mineral selected from CaF ₂ and CaF ₂ ; fineness is 2000 to 5000 cm ² / g by Blaine specific surface area measurement
In the method for producing special cement, which is within the range of Ca
Raw materials selected from O raw materials, SiO ₂ raw materials, A ₂ O ₃ raw materials and F raw materials or steelmaking slag, blast furnace slag, and alloy production slag are fired in a temperature range of 1000 to 1200 ° C., cooled, coarsely crushed and finely ground. A method for producing a special cement, comprising crushing. 2. The method for producing a special cement according to claim 1, wherein the special cement can contain up to 2% by weight of a boron component as B ₂ O ₃ . 3. A special cement, characterized in that activated silica is added to the special cement produced by the method for producing special cement according to claim 1 or 2 in an amount of 5 to 35% by weight based on the total weight.