JPH09132477A - Inorganic foamed body and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize slag formed at the time of performing a petroleum coke gasification reaction and to produce a novel inorganic foamed body having high strength and low water absorption properties by firing amorphous slag at a temp. within a specified range. SOLUTION: In this production, amorphous slag which contains an inorganic material that consists of 30 to 52wt.% SiO2 , 15 to 35wt.% intermediate oxide, 10 to 35wt.% network modifier oxide and a 1 to 5wt.% crystal nucleus forming agent, and also >=0.2wt.% H2 O in the form of Si-OH and into which >=0.2wt.% of at least one component selected from H2 , H2 , CO2 , and CO is dissolved, is fired at a temp. within the range of a temp. at which a crystalline substance begins to separate out (600 to 850 deg.C) to a temp. by 50 deg.C higher than the glass softening point (700 to 900 deg.C). This fired body consists of an inorganic material which has the above composition and a structure comprising an amorphous phase and fine crystals that are dispersed and separate out in the amorphous phase. Thus, the fired body, namely the objective inorganic foamed body can be produced.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel inorganic foam and a method for producing the same.

[0002]

2. Description of the Related Art The method for producing an inorganic foam can be roughly classified into a melting method and a firing method. The melting method is to flow down the molten raw material, blow a high-pressure gas from it to the nozzle, atomize the melt and incorporate bubbles into the melt by using the viscosity and surface tension of the melt, This is a method of solidifying. Inorganic foams produced by this method include balloons such as alumina, zirconia, and magnesia spinel. However, this method has problems that a large amount of energy is required to melt the raw material having a high melting point and that the yield at the time of atomizing the melt is poor.

On the other hand, in the firing method, a raw material containing a substance that generates a gas is heated to a temperature at which an amorphous phase having a viscosity that allows the generated gas to be taken inside is generated, and the generated gas is generated. This is a method of foaming by pressure. The raw material for forming an amorphous phase having an appropriate viscosity is in the range of a certain chemical composition, Riley (J. Am. Ceram. So.
c., Vol.34, No.4, P.121 (1951)). Its chemical composition is 52 to 79% by weight of SiO ₂ , Al ₂ O ₃
Is 11 to 26% by weight, and the flux component such as alkali is 7 to 2
4% by weight. Conventionally used raw materials include pearlite, obsidian, pine rock, shirasu, expanded shale, expanded viscosity,
There are fly ash, etc., and their chemical compositions are within the range shown by Riley. In the chemical composition within this range, the temperature at which an amorphous phase having an appropriate viscosity is formed is 900 ° C or higher. Material generating gases is different from a source, perlite, obsidian, pitchstone, glassy volcanic shirasu such H ₂ O is, expanded shale, consider expanding viscosity, fly ash, etc. iron compound and foaming source Has been. The temperature at which H ₂ O in glassy volcanic rock is gasified is 150 to 900 ° C., and oxygen is generated by reduction of iron compounds at 1000 ° C. or higher.

In order to produce an inorganic foam by the firing method, it is necessary to match the temperature at which an amorphous phase having an appropriate viscosity is formed with the temperature at which a gas is generated, but this is not always the case for actual raw materials. For this reason, there are problems such as rapid heating at the time of firing, and an unnecessarily high firing temperature. Further, when the conventional raw material is used, the foaming state is adjusted by adjusting the amount of gas generated, so that problems such as the shell of the inorganic foam being broken due to overfoaming occur, and a low water absorption rate. It has been difficult to produce a high strength inorganic foam.

[0005]

OBJECTS OF THE INVENTION It is an object of the present invention to provide a novel inorganic foam and a method for producing the same. It is also an object of the present invention to provide a method for effectively utilizing slag generated during a petroleum coke gasification reaction, which has not been conventionally used effectively.

[0006]

According to the present invention, 30 to 52% by weight of SiO ₂ , 15 to 35% by weight of an intermediate oxide, 10 to 35% by weight of a network modifying oxide and 1% of a crystal nucleating agent are used.
The present invention relates to an inorganic foam characterized by comprising an inorganic content of up to 5% by weight, the inorganic being composed of an amorphous phase and fine crystals dispersed and precipitated in the amorphous phase. The inorganic foam of the present invention is different from the inorganic foam obtained from pearlite, obsidian, pine rock, shirasu, expanded shale, expanded viscosity, fly ash, etc., and has high strength in which the inorganic substance is reinforced by fine crystals dispersed and precipitated. , A novel inorganic foam with low absorption.

As intermediate oxides, Al ₂ O ₃ and Fe ₂ O _{3 are used.}
And at least one oxide selected from TiO ₂ . Further, as the network modifying oxide, CaO,
At least one oxide selected from MgO, Na ₂ O and K ₂ O can be mentioned. As the crystal nucleating agent, P ₂
O ₅ and / or V ₂ O ₅ may be mentioned.

The inorganic foam of the present invention contains 30% of SiO ₂ .
˜52 wt%, 15 to 35 wt% intermediate oxide, 10 to 35 wt% network modifying oxide, 1 to 5 wt% crystal nucleating agent and 0.2 wt% or more in the Si—OH state. H ₂ O
Amorphous slag containing 0.2% by weight or more of at least one component selected from H ₂ O, H ₂ , CO ₂ and CO is contained at 50 ° C. from the crystal crack initiation temperature and the glass softening point.
It can be produced by firing in a temperature range between high temperature. When fired at a temperature lower than the crystal cracking start temperature, the viscosity of the slag is high, so that it does not sufficiently foam. Further, when the firing is performed at a temperature higher than the glass softening point by 50 ° C. or more, the viscosity of the slag is too low and the foams are fused to each other.

Amorphous slag, which is a raw material for producing the inorganic foam of the present invention, is a chemical component which is conventionally used as a raw material for pearlite, obsidian, pine rock, shirasu, expanded shale, expanded viscosity, fly ash and the like. Is different. In particular, this amorphous slag has a low content of SiO ₂ which is a network-forming oxide,
Since it contains 15 to 35% by weight of the intermediate oxide and 10 to 35% by weight of the network modifying oxide, the amorphous softening point is lower than that of the conventional raw material and is in the range of 700 to 900 ° C. . Therefore, by using this amorphous slag, it is possible to foam at a lower firing temperature than conventional.

Further, the amorphous slag has a smaller content of SiO ₂ which is a network-forming oxide than the conventional raw materials,
1 to 5% by weight of a crystal nucleating agent that promotes amorphous crystallization
Since the amorphous phase is included, the amorphous phase becomes unstable, and the crystal crack initiation temperature is in the range of 600 to 850 ° C. Therefore, the obtained inorganic foam becomes a particle dispersion-strengthened amorphous in which fine crystals are dispersed in an amorphous phase, and has high strength. Further, since fine crystals are precipitated in the amorphous phase during foaming, the viscosity of the slag increases and the foam shell is less likely to be broken by gas pressure, and an inorganic foam with a low water absorption rate can be obtained. .

Further, the amorphous slag contains 0.2% by weight or more of H ₂ O in the state of Si-OH, and H ₂ O, H ₂ ,
At least one component selected from CO ₂ and CO is 0.2
It is an amorphous slag that is dissolved by weight% or more. Si-O
The temperature at which H ₂ O existing in the state of H is desorbed from the amorphous phase and gas is generated is 500 to 1000 ° C., and the amorphous slag of the present invention has an amorphous softening point from the crystal precipitation start temperature. It almost coincides with the temperature range of. Therefore, the inorganic foam can be manufactured without using a special firing method such as rapid temperature rising. In addition, H ₂ dissolved in the amorphous slag
O, H ₂ , CO ₂ and CO are Si which is a network forming oxide.
Destroying Si-O-Si bonds of the O _2, to reduce the viscosity of the amorphous phase, to facilitate foaming of amorphous slag. These dissolved molecules are desorbed from the amorphous phase at the end of foaming and recombine the broken Si-O-Si bond, so that the viscosity of the amorphous phase after the completion of foaming is increased and the inorganic foam is Prevents fusion between them.

The amorphous slag used in the present invention is melted at a temperature higher than the flowing temperature in an atmosphere of at least one gas selected from H ₂ O, H ₂ , CO ₂ and CO pressurized to 2 atm or more. It is obtained by rapidly cooling the slag. Below 2 atm, H ₂ O in the Si—OH state is contained in an amount of less than 0.2% by weight, and at least one component selected from H ₂ O, H ₂ , CO ₂ and CO is also less than 0.2% by weight. Only dissolved in amorphous slag.

The amorphous slag used in the present invention is supplied as slag generated when producing synthesis gas by partial oxidation of petroleum coke. In particular, like the Texaco method, water slurry of petroleum coke and flux is sprayed into a gasification furnace under high pressure, the reaction is carried out at a temperature above the flow temperature of the generated slag, and the generated slag is dropped into water and rapidly cooled. It is preferred to use the amorphous slag discharged from the device. Usually, petroleum coke has ash as SiO ₂ , Al ₂
Since O ₃ , V ₂ O ₅ , NiO and the like are contained and these are discharged from the reaction furnace, flux is added to generate slag and the slag is discharged to the outside of the reaction furnace. Therefore, an amorphous slag having the composition of the present invention is produced by adjusting the chemical composition of the flux to be added.

The flux used to adjust the chemical composition of the slag is not particularly limited, but includes coal ash, blast furnace slag,
Clay, limestone, sewage sludge, silica sand, etc. can be used. The particle size of the amorphous slag used in the present invention is not particularly limited, but the surface area per unit volume becomes large when the particle size becomes small, and the gas generated in the amorphous slag easily escapes from the surface and is difficult to foam. There is a tendency to become. Since the inorganic foam of the present invention has extremely low water absorption and high strength, it can be used as a lightweight aggregate for cement.

[0015]

The present invention will be described more specifically with reference to the following Examples and Comparative Examples. Example 1 As a result of X-ray diffraction, it was confirmed that the slag discharged from the Texaco petroleum coke gasification furnace operating at a pressure of 40 atm and a temperature of 1500 ° C. was amorphous. Table 1 shows the chemical components, the H ₂ O content in the Si—OH state by the infrared absorption spectrum, and the gas dissolution amount by the thermal desorption gas analysis. The crystal precipitation start temperature was 750 ° C and the glass softening point was 780 ° C. Next, crush the amorphous slag,
After classifying to a particle size of 0.6 to 1.2 mm, 100 g of these particles are put into an electric furnace and heated at a temperature rising rate of 10 ° C./min to 800.
The mixture was heated to 0 ° C and held for 6 minutes for foaming. About the obtained inorganic foam, unit volume weight, 24-hour water absorption,
The crushing strength and X-ray diffraction were measured. Table 2 shows the results of the foaming test.

Example 2 In Example 1, the crushed amorphous slag particles were
An inorganic foam was produced in the same manner as in Example 1 except that the size was classified to 2 to 2.4 mm. Table 2 shows the results.

Example 3 In Example 1, the pulverized amorphous slag particles were mixed with 0.1
An inorganic foamed product was produced in the same manner as in Example 1 except that the product was classified to 4 to 0.6 mm. Table 2 shows the results.

Comparative Example 1 In Example 1, except that the firing temperature was 900 ° C.,
An inorganic foam was produced in the same manner as in Example 1. The inorganic foam melted and the particles were fused together.

Comparative Example 2 An inorganic foam was produced in the same manner as in Example 1 except that the amorphous slag having the chemical composition shown in Table 1 was used. The inorganic foam remained amorphous and over-foamed to increase water absorption and reduce crush strength.

Comparative Example 3 Same as Example 1 except that the amorphous slag prepared by pouring the slag melted at a pressure of 1 atm and a temperature of 1500 ° C. into water and quenching was used. Although an attempt was made to produce an inorganic foam, the amorphous slag contained very little foaming component, and the inorganic foam could not be obtained by firing.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

INDUSTRIAL APPLICABILITY The inorganic foam of the present invention can be produced by using the amorphous slag generated during the gasification of petroleum coke, which has not been conventionally used effectively, and can contribute to the effective use of resources. Further, since a part of the amorphous is crystallized at the time of foaming, it is possible to provide an inorganic foam having high strength and low water absorption.

Claims (3)

[Claims] 1. An inorganic material containing 30 to 52% by weight of SiO ₂ , 15 to 35% by weight of an intermediate oxide, 10 to 35% by weight of a network modifying oxide, and 1 to 5% by weight of a crystal nucleating agent. An inorganic foam characterized in that the inorganic material is composed of an amorphous phase and fine crystals dispersed and precipitated in the amorphous phase. 2. SiO ₂ of 30 to 52% by weight, an intermediate oxide of 15 to 35% by weight, a network modifying oxide of 10 to 35% by weight, a crystal nucleating agent of 1 to 5% by weight and Si--OH. In the state, it contains 0.2% by weight or more of H ₂ O, H ₂ O, H ₂ ,
At least one component selected from CO ₂ and CO is 0.2
A method for producing an inorganic foam, which comprises calcining an amorphous slag, which is melted in an amount of not less than wt%, in a temperature range between a crystal cracking initiation temperature and a temperature 50 ° C. higher than a glass softening point. 3. The amorphous slag is pressurized to 2 atmospheres or more
H_TwoO, H_Two, CO _TwoAnd at least selected from CO
Melted at a temperature above the flow temperature in a kind of gas atmosphere
The non-flakes according to claim 2, which are obtained by quenching slag.
A method for manufacturing an organic foam.