JPS5927731B2 - Method for producing calcia clinker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing calcia clinker, which has excellent properties as a refractory such as resistance to digestion and hot bending strength.

More specifically, the main raw material is calcia (Cab), and two or more compounds of boron or aluminum, which is an element in group Ⅰ of the periodic table, and/or silicon or titanium, which is an element in group Ⅰ of the periodic table. Alternatively, the present invention relates to a method for producing calcia clinker having excellent properties not previously available, by mixing and pulverizing a substance to which these substances and calcium fluoride are added, followed by molding and firing.

Traditionally, calcia has an extremely high melting point of 2,580°C, has great resistance to basic slag, and has extremely strong dephosphorization, desulfurization, and deoxidizing effects, so it is used as a refractory material in steelmaking furnaces, ladles, cement firing furnaces, etc. It is expected that.

However, calcia is difficult to handle, and has the major disadvantage that, especially when left in the atmosphere, it absorbs moisture from the atmosphere, becomes powdered by the reaction described below, and finally disintegrates.

In other words, the resistance to digestion is extremely low, and the strength is also reduced, so that it has not been put into practical use at present.

CaO+H20→Ca(OH)2 Various studies have been conducted and proposed as methods to improve this drawback, but the main ones are (1) a method of melting lime raw material at a high temperature higher than the melting point of calcia.

(2) A method of firing lime raw materials at high temperatures.

(3) A method of adding and mixing other components to the lime raw material.

and so on.

That is, as for (1), a small amount of S i02 in calcia
.

A method of manufacturing refractories by adding F e203 etc. and melting at 3000℃ or higher for several hours (Japanese Patent Publication No. 50-372
03), and (2), Calcia is 16
After heating at a temperature of 00℃ or higher and lower than the melting point for 2 hours or more, 1
Cooled at a rate of 00℃/hr until the calcia crystal diameter was 5μ.
There are methods for producing clinker having the above particles (Japanese Patent Laid-Open No. 52-53908), and (3) a method of adding 0.4 to 1.3 mol% of Fe2O3 to calcia (Japanese Patent Laid-Open No. 52-53908). No. 53-55311) and Fe2O3
and a method of adding 2 to 10% TiO
-14709).

However, in the above method, method (1) requires a large amount of thermal energy as calcia must be calcined to a temperature above its melting point, which not only poses economical problems but is also not suitable for mass production. The anti-digestion method is also bad.

(2) is lower than the melting point of calcia, but requires a large amount of thermal energy because the field is burned at a high temperature and for a long period of time, and there are limits to the cooling rate to obtain clinker with good properties, so it cannot be obtained using a normal rotary kiln. Similarly to (1), the digestion resistance was also not improved.

Furthermore, (3) has a high firing temperature and is Fe2O.

The clinker obtained by adding these substances has the disadvantage that its hot bending strength and corrosion resistance are inferior.

The present inventors conducted extensive research with the aim of further improving the quality and establishing a method for producing calcia clinker that can be used industrially.

That is, calcia is used as the main raw material, and two or more compounds of boron, element, or aluminum, which are elements of group Ⅰ of the periodic table, and/or silicon or titanium, which are elements of group Ⅰ of the periodic table, are used, more preferably. It was discovered that by adding and mixing these and calcium fluoride in a specific range of amounts, pulverizing the mixture, molding it, and then sintering it, it is possible to industrially produce high-quality calcia clinker that was previously unobtainable. , completed the invention.

The raw materials for producing calcia used in the present invention include, for example, limestone, Caco3. There is no particular limitation, and any material containing calcium as a main component such as Ca(OH)2 may be used.

However, from the viewpoint of the quality of the calcia clinker obtained, Fe
It goes without saying that it is preferable to have less alkali such as 2O3, Na2O, and 20, as well as harmful components such as sulfur and phosphorus.

Furthermore, the firing temperature for obtaining calcia from the raw materials must be changed depending on the type of raw materials and the method of mixing calcia and the above-mentioned additives.

1100 when mixing when the raw material is in the form of CaCO3
~1300°C is preferred.

When the smoking temperature is below 1100℃, the activity of calcia is high but the filling properties are poor, and when the smoking temperature is above 1300℃, the filling properties of calcia are high but the activity is poor, so the digestion resistance of the clinker obtained in either state is low. I have bad sex.

Further, when mixing calcia and additives in the presence of water, there is no need to particularly limit the heating temperature, but it is preferably about 1000°C.

When mixing when the raw material is in the form of Ca(OH)2,
The firing temperature is preferably 900 to 1300°C, and when mixing in the presence of water, it is preferably about 800°C, although there is no particular limitation.

(2) When the firing temperature is below 900°C or above 1300°C, it exhibits the same drawbacks as CaCO3.

The additive substances in the present invention may include compounds of boron or aluminum, which are elements in group Ⅰ of the periodic table, and/or silicon or titanium, which are elements in group Ⅰ of the periodic table, and calcium fluoride. .

Since these additive substances are usually used at high temperatures, it is preferable that they form stable oxides under high temperature conditions, such as Al2
Examples include O3, B2O3, TiO2, and 5i02.

As calcium fluoride, industrial fluorite is usually sufficient.

In the present invention, the amount of the compound of boron or aluminum, which is an element in group Ⅰ of the periodic table, and/or the compound of silicon or titanium, which is an element in group Ⅰ of the periodic table, is calculated based on the pure content (Cab) of calcia. On the other hand, the content of the additive material is preferably 0.5 to 3 wt% based on the oxide.

If it is less than 0.5 wt%, the digestion resistance of the calcia clinker will deteriorate, and if it is added more than 3 wt%, the digestion resistance and bending strength will not improve as expected.

Furthermore, when calcium fluoride is added, it is preferably 0.5 to 2 wt% based on the amount of calcia in terms of pure content.

If the amount is less than 0.5 wt%, the digestion resistance of the calcia clinker will be poor, and if it is more than 2 wt%, the digestion resistance and bending strength will be similarly bad.

To obtain a pulverized mixture from calcia and the above-mentioned additives, pulverization using a ball mill or the like or mixing using a type mixer etc. is sufficient. The mixture may be mixed with the additive and then pulverized.

Alternatively, a calcia hydrate may be prepared and a ground additive substance may be added thereto, or a calcia hydrate may be prepared by adding a ground additive substance.

The mixing and pulverization may be carried out in the solid state, or may be carried out in the presence of water without any problem.

The fineness of the calcia and additives used in the present invention is preferably 5000 cr7t/g or more based on Blaine specific surface area.

If the calcia clinker is less than 5000 cut 79, the digestibility of the calcia clinker is poor.

The mixture of pulverized calcia and additives is usually molded using a briquette machine or a pan-type granulator, since molding improves the properties of the clinker after firing, such as its resistance to digestion.

In the present invention, the firing temperature for obtaining clinker from the mixture of calcia and additive substances is determined by the firing temperature of boron or aluminum, which is an element of group 1 of the periodic table, and/or silicon or titanium, which is an element of group 1 of the periodic table. When only the compound is added, the temperature is preferably 1400 to 1650°C.

If the temperature is below 1400°C, the clinker will have poor digestion resistance due to insufficient firing.

Even at temperatures above 1650°C, the digestion resistance of the clinker does not improve as expected.

Furthermore, when calcium fluoride is added, the firing temperature can be lowered and is preferably 1200 to 1650°C.

Below 1,200°C, the calcination is insufficient and the digestion resistance of the clinker deteriorates; above 1,650°C, the digestion resistance of the clinker deteriorates due to porosity caused by volatilization of calcium fluoride.

By putting the present invention into practical use, it is possible not only to obtain calcia clinkers that exhibit superior values in terms of digestion resistance and bending strength, but also to produce these excellent clinkers at lower firing temperatures than conventional ones. It has the great advantage of being easy to manufacture.

Next, practical examples and comparative examples of the present invention will be specifically explained.

In the present invention, the digestion resistance is determined by the clinker after firing.
After adjusting the grinding to about 3 mm, 2 at 3 kg/crit.
After autoclaving for a time, the weight increase rate (c) due to the digestion reaction was determined.

In addition, the hot bending strength is 297 after crushing the clinker.
~150μ 30wt%, 149~75μ 15wt%
.

74μ or less Adjust to 55wt%, 500”
; Pressure molded at t/criY.

This molded product was fired at 1700°C for 1 hour and a specimen (25X
25×120 strips) were manufactured.

Using this specimen, the hot bending strength k at 1450℃
g/cr7L) was measured.

Actual Cases 1 to 4 Limestone was calcined at 1200°C for 3 hours to obtain calcia having the composition shown in Table 1.

To this, predetermined amounts of Al2O3, B2O3, 5IO2 and TiO□ (all special grade reagents) shown in Table 2 were added, and a Blaine specific surface area of 6000 cyi! was added using a ball mill. / g
The mixture was ground and mixed to obtain a finely ground product.

The obtained finely pulverized material was pressurized at 2't/i- to give 6cIrL.
A molded product of φX2 (XH) was produced, which was again crushed into pieces of 5 mm or less and fired at 1600° C. for 1 hour.

Table 2 shows the physical properties of the calcia clinker obtained by cooling.

Comparative Examples 1 to 5 No addition or only one type of compound of boron or aluminum, which is an element in group Ⅰ of the periodic table, and/or silicon or titanium, which is an element in group Ⅰ of the periodic table,
Other than that, the experiment was conducted under the same conditions as in actual case 1.

The results are shown in Table 2. Actual Example 5, 6 In Actual Example 1, the amount of Al2O3 added is 0.5 wt.
%.

The amount of SiO□ added is 0.5wt% (actual example 5), the amount of Al2O3 added is 2wt%, and the amount of SiO□ is 2w.
The experiment was conducted under the same conditions as in Actual Example 1, except that the concentration was changed to t% (Example 6).

The results are shown in Table 3. Comparative Examples 6, 7 In Actual Example 1, the temperature at which the limestone was baked was set at 1000℃ (
The experiment was conducted under the same conditions as in Comparative Example 6) and 1400°C (Comparative Example 7), except that the temperature was changed to 1400°C (Comparative Example 7).

The results are shown in Table 4. Actual Case 7 Experiment 1 was conducted under the same conditions as Actual Case 1 except that the Blaine specific surface area in Example 1 was changed to 8000 d/y.

The results are shown in Table 5. Comparative Example 8 In Actual Example 1, the Blaine specific surface area was 4000 cyyt.
The experiment was conducted under the same conditions as in Actual Example 1, except that the value was changed to /g.

The results are shown in Table 5. Actual example 8, 9 In actual example 1, the firing temperature is 1400℃ (actual example 8),
The experiment was conducted under the same conditions as in Example 1 except that the temperature was changed to 1800°C (Example 9).

The results are shown in Table 6.

Comparative Example 9 An experiment was conducted under the same conditions as Actual Example 1 except that the firing temperature was changed to 1200°C.

The results are shown in Table 6.

Actual case 10 The ingredients added in Actual example 1 were A12031wt%,
The experiment was conducted under the same conditions as in Actual Example 1, except that SiO21wt% and CaF21wt% were used.

The results are shown in Table 7.

Actual Example 11 An experiment was conducted under the same conditions as Actual Case 10, except that the amount of CaF2 added in Actual Case 10 was 2 wt%.

The results are shown in Table 7. Comparative example 10 The amount of C a F2 added in actual case 10 was 3wt.
The experiment was conducted under the same conditions as in actual case 10, except that the percentage was closed.

The results are shown in Table 7. Actual Cases 12 and 13 In Actual Case 10, the firing temperature was set at 1400'C (Actual Example 1).
2) and 1200°C (older sister example 13), but the experiment was conducted under the same conditions as the older sister example 10.The results are shown in Section 8.
Shown in the table.

Comparative Example 11 An experiment was conducted under the same conditions as Actual Case 10 except that the firing temperature was changed to 1800°C.

The results are shown in Table 8. Hushu υυ 17 rin l 4 The ingredients added in Example 1 were Al5O12wt%,
S 102 1 wt% and T ! 021w
The experiment was conducted under the same conditions as in Example 1, except for closing the sample by t%.

Digested weight increase rate of obtained calcia clinker: 1.8%
Hot bending strength at 1450℃ is 270 kg/c
It was ii.

Actual Example 15 757 g of calcia having the composition shown in Table 1 obtained by smoking limestone at 1000° C. for 3 hours was mixed with water 424, 39 to obtain a slurry with a solid content concentration of 20 wt%.

The same amount of the additives used in Example 1 was added to this slurry, mixed with a stirrer for 2 hours, and then the precipitate was separated.

The obtained 1015 g of precipitate was heated and dried at 105° C. for 4 hours, and then a 4×4×8 CrIL molded product was produced under a pressure of 0.5 t/i.

This was crushed to a size of 5 mm or less and then baked at 1600° C. for 1 hour.

The results are shown in Table 9.

Actual Case 16 An experiment was conducted under the same conditions as Actual Sister Example 15, except that the additives in Actual Sister Example 15 were changed to Actual Sister Example 1, and the firing temperature was changed to 1200°C.

The results are shown in Table 9. Comparative Example 12 to Step 5 Method using the conditions of JP-A-50-37203 (Comparative Example 12), method according to JP-A-52-53908 (Comparative Example 13), method according to JP-A-53-55311 (Comparative Example 12) Example 14) and molten calcia or clinker were produced by the method according to JP-A-50-14709 (Comparative Example 15).

The physical properties of the obtained products were measured under the same conditions as in the present invention and are shown in Table 10.

In addition, the values of Example 1 are shown, indicating that the clinker according to the present invention has excellent physical properties.

17 Experiments were conducted under the same conditions as in Example 1, except that calcia having the composition shown in Table 11, which was obtained by roasting gypsum at 1200°C for 3 hours in a reducing atmosphere, was used as the lime raw material. Ta.

The increase rate of the digested weight of the obtained calcia clinker was 2.0
% hot bending strength at 1450℃ is 270kg/c
It was I7L.

Claims (1)

[Claims] 1. When producing calcia clinker using calcia obtained by time-burning lime raw materials as the main raw material, boron or aluminum, which is an element in group Ⅰ of the periodic table, and/or
Alternatively, a method for producing a calcia clinker, which comprises adding two or more compounds of silicon or titanium, which are elements of group 1 of the periodic table, or calcium fluoride and these together.