JPH0251858B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF THE INVENTION The present invention relates to novel inorganic foam particles and methods of making the inorganic foam particles. [Background of the Invention] Inorganic foam particles can be used as lightweight aggregates for structures, fillers (agents) for fertilizers, detergents, paints, etc. by taking advantage of their light weight and foam properties. It is widely used as an adsorbent and soil improvement material. Such known inorganic foam particles can be broadly classified into glass balloons made from artificial raw materials, glass balloons made from natural raw materials, perlite, flyash balloons, and expanded shale. Glass balloons are foam particles made by expanding particles containing sodium silicate as a main component obtained by a method such as a droplet method or a dry gel method. Shirasu balloons are manufactured by heating and foaming shirasu, whose main component is volcanic glass. Pearlite is manufactured by similarly heating and foaming pearlite, obsidian, pinestone, trachyte, etc. Furthermore, a fly ash balloon is a foam obtained by floating and separating coal ash obtained by burning pulverized coal into water. Expanded shale is produced by heating and foaming shale in the same way. For example, the manufacturing process for glass balloons is complicated, and for glass balloons, pearlite, and expanded shale, minerals are mined from mountainous areas and crushed. Furthermore, in recent years, there has been a problem of environmental destruction caused by mining, and it has become increasingly difficult to obtain raw materials year by year. Furthermore, in the case of fly ash balloons, they themselves have their own problems, such as being contained in part of the coal ash generated during thermal power generation, making it difficult to provide a stable supply. Furthermore, the unit volume weight of these inorganic foam particles is 0.02 to 0.05 Kg/(e.g. perlite) or 0.15 to 0.4 Kg/(e.g. glass balloon).
There are many inorganic foam particles having a unit volume weight in the range of 0.6 to 1.2 kg/. The present inventor has determined that the content of SiO ₂ in the components forming the inorganic foam particles is 60% by weight or less, the content of Al ₂ O ₃ is 20% by weight or more, and the content of CaO is 5% by weight or more. An application has already been filed for an invention relating to certain inorganic foam particles and a method for producing the same (patent application
No. 60-35066). [Object of the Invention] An object of the present invention is to provide novel inorganic foam particles. A further object of the present invention is to provide a method for producing this new inorganic foam particle. Another object of the present invention is to provide a method for effectively utilizing the residue generated during the coal gasification reaction, which has hitherto had no effective use. [Summary of the Invention] The present invention includes SiO ₂ , Al ₂ O ₃ , and CaO,
Inorganic foam particles having air bubbles inside,
The content of SiO ₂ in the inorganic foam forming component is 60
% by weight or less, the content of Al ₂ O ₃ is 20% by weight or more, the content of CaO is 5% by weight or more, and the unit volume weight of the particles of the inorganic foam is more than 0.6 Kg / 1.2 Kg/or less, and the inorganic foam particles have a particle diameter in the range of 0.5 to 3.5 mm. The inorganic foam particles of the present invention are novel inorganic foam particles having a composition that is clearly distinguished from various known inorganic foam particles, such as glass balloons, glass balloons, perlite, flyash balloons, and expanded shale. It is the body. The inorganic foam particles of the present invention are amorphous residue particles obtained by partial oxidation of coal, and the particle size is
It can be easily manufactured by a manufacturing method that consists of heating a material of 2.5 mm or less at a temperature of 600° C. or higher to expand and foam it. [Effects of the Invention] The inorganic foam particles of the present invention can be manufactured using amorphous residue particles generated during coal gasification, which have not had any effective use in the past, and further Because it expands at a lower temperature than conventional natural raw materials, it is possible to effectively utilize resources for which no effective use has been developed in the past, and at the same time reduce the manufacturing cost of inorganic foam particles. In addition, the inorganic foam particles of the present invention have extremely high strength, are lightweight, and have low water absorption and thermal conductivity, making them particularly suitable for use as lightweight aggregates. be. [Detailed Description of the Invention] The inorganic foam particles of the present invention are inorganic foam particles containing SiO ₂ , CaO and Al ₂ O ₃ and have these three components as main components. The inorganic foam particles of the present invention may also contain, for example, iron oxide, Na ₂ O, K ₂ O, etc. in addition to the above three components. The inorganic foam particles of the present invention contain SiO ₂ in the component.
The content of _Al2O3 is 20% by weight or more (preferably 20-40% by weight), and the content of CaO is 60% by weight or less (preferably 30-60% _by weight). It is 5% by weight or more (preferably 5 to 30% by weight). Generally, these three components are contained in an amount of 60% by weight or more, preferably 70 to 95% by weight, particularly preferably 75 to 95% by weight, based on the inorganic foam forming components. The inorganic foam particles of the present invention usually contain components such as iron oxide, MgO, Na ₂ O, and K ₂ O in addition to the above three components. Generally, these other ingredients are
The content is 40% by weight or less, preferably 5 to 30% by weight, particularly preferably 5 to 25% by weight, based on the inorganic foam forming components. The content of each of these other components is usually 2 to 15% by weight based on Fe ₂ O ₃ for iron oxide, 1 to 7% by weight for MgO, and 1 to 1% by weight for Na ₂ O, based on the inorganic foam-forming components. 6% by weight, _K2O is 0
~2% by weight. Furthermore, in addition to the above components, trace amounts of TiO ₂ , SO ₃ , other sulfides or sulfur compounds, and carbon components may also be included. The inorganic foam particles of the present invention have a unit weight of
It is within the range of 0.6 to 1.2 kg/. However, 0.6Kg/ is not included. Moreover, when this unit volume specific gravity is expressed in apparent specific gravity, it is in the range of about 1.21 to 2.10. The inorganic foam particles of the present invention mainly have closed cells in the particles. Therefore, it has an extremely low water absorption rate, and for example, when mixed with cement as an aggregate to prepare cement mortar, the water-cement ratio can be lowered, and the strength of the resulting hardened cement product is extremely high. Furthermore, since the amount of water contained in the mortar is small, freezing and thawing of the hardened cement can be effectively prevented. However, all the cells do not have to be closed cells, and the above characteristics can be maintained as long as at least 70% of the cells are closed cells. It also has the advantage of low thermal conductivity because it contains a large number of bubbles. The inorganic foam particles of the present invention have higher strength compared to known inorganic foam particles, usually 10 to 70 kgf.
(the average value of the crushing strength measured by randomly selecting 20 inorganic foams of the present invention with a particle size of 2 to 2.5 mm). Therefore, the inorganic foam particles of the present invention hardly disintegrate during storage or transportation, and furthermore, the inorganic foam particles of the present invention can be used as lightweight aggregate when constructing structures. By doing so, a structure with high strength and toughness can be obtained. The inorganic foam particles of the present invention generally have a particle diameter of 3.5 mm or less (preferably about 0.5 to 2.8 mm).
belongs to. Next, a method for manufacturing the inorganic foam particles of the present invention will be explained. The inorganic foam particles of the present invention can be produced by heating those having a specific particle size among the amorphous residue particles obtained by partial oxidation of coal under specific conditions. The amorphous residue particles used as a raw material are preferably obtained by partial oxidation of coal. For example, ash produced by combustion in an atmosphere in which pulverized coal is completely combusted does not foam effectively and cannot be used for producing inorganic foam particles. The amorphous residue particles utilized for the production of inorganic foam particles are supplied as residues generated during the production of synthesis gas, for example by partial oxidation of lime. Examples of methods for producing synthesis gas using such coal include the Lurgi process, Winkler process, Koppers-Tochiek process, and Otsuto-rumen process, as well as the KDV process, the Lurgi Slugging process, the Shinzan process, the NWH process, U gas method, HYGAS method, coal engineering method, pressurized fluidized hydrogen gasification method, hybrid method,
Coal gasification methods such as the HTW method, BIGAS method, Siel (Siel Koppaz) method, Saalbach-Otto method, Sumitomo method and Texaco method can be mentioned. In the production method of the present invention, in particular, partial oxidation of coal such as the Koppaz Tochiek method, the Otto Rumen method, the Rurgislagging method, the Siel (Siel Koppaz) method, and the Texaco method is carried out by softening the coal in a gasifier. Preference is given to using amorphous residues discharged from coal gasifiers operating at temperatures above point. For example, in the Texaco process, coal is put into a coal gasifier as a water slurry, heated under pressure to a temperature above the softening point of ash, generally about 1300 to 1500°C, and partially oxidized. At this time, a molten or semi-molten residue is generated, and this residue is usually cooled with water or the like, then pulverized if necessary, and discharged from the coal gasifier. The details of coal gasification methods such as the Texaco method are described in detail in the August and September 1981 issues of Kagaku Keizai. Although the composition of the amorphous residue generated by partial oxidation of coal varies depending on the type of coal used as a raw material for coal gasification, etc., in the method for producing inorganic foam particles of the present invention, Regardless, the amorphous residue produced during partial oxidation of coal, such as coal gasification, can be used. Generally, the amorphous residue as described above contains SiO ₂ in the range of 60-30% by weight, Al ₂ O ₃ in the range of 20-40% by weight and CaO in the range of 5-30% by weight, and small amounts of sulfides or Contains sulfur compounds and unburned carbon. In particular, the content of combustible components involved in foaming, such as sulfide sulfur and unburned carbon, is 1% by weight.
It is preferable that it is below. When the content exceeds 1% by weight, the unit volume weight of the inorganic foam particles obtained may be less than 0.6 kg/kg, and the crushing strength of the obtained inorganic foam particles may not be sufficiently high. The residue obtained by partial oxidation of coal is amorphous and therefore does not show any specific peaks even when subjected to X-ray diffraction. The amorphous residue particles used have a particle size of 2.5 mm or less. The particle size is 2.5 mm or less, and the content of residues of 0.6 mm or less is 20% by weight or less. If particles having a particle size exceeding 2.5 mm are used, inorganic foam particles having a unit volume weight within the range of the present invention cannot be obtained. In addition, if the amorphous residue particles contain much more than 20% by weight of particles with a particle size of 0.6 mm or less, the foamability of the amorphous residue with a small particle size is poor, resulting in inorganic foaming. The inorganic foam particles may contain particles that are not sufficiently foamed, and the unit volume weight of the inorganic foam particles may exceed the scope of the present invention. During heat treatment, the residue discharged from the coal gasifier is crushed, and then particles larger than 2.5 mm are removed using conventional methods such as sieving. The residual particles whose particle diameter etc. have been adjusted in this manner are then subjected to heat treatment. Heat treatment is performed at a temperature of 600°C or higher. moreover
It is preferred to carry out at a temperature within the range of 600-900°C, particularly preferably at a temperature within the range of 650-850°C. At temperatures below 600°C, amorphous residue particles do not expand effectively. Furthermore, if the heat treatment temperature exceeds 900°C, the expanded residual particles may melt, and the generated air bubbles may disappear. The heat treatment can be carried out by directly introducing the residual particles into a furnace or the like that has been adjusted to the heat treatment temperature in advance, but is usually carried out by gradually raising the temperature of the residual particles. In the method of gradually increasing the temperature, for example, the rate of temperature increase is generally controlled using a rotary kiln, etc.
The temperature is set at 150°C/min or less (preferably within the range of 1 to 100°C/min). If the temperature is increased more rapidly than this value, closed cells may not be effectively formed during expansion, and the water absorption of the foam particles tends to increase. Generally, the heat treatment is carried out using a heating device such as a rotary kiln or a furnace using an airflow firing method, which is commonly used in the production of whitebait balloons, pearlite, and the like. A method in which heat treatment is performed by gradually raising the temperature is particularly suitable for production on an industrial scale. The heat treatment temperature and treatment time for the inorganic foam particles of the present invention are lower and shorter than the heating temperatures used in producing known inorganic foam particles such as shirasu balloons and perlite. Therefore, the inorganic foam particles of the present invention can be manufactured with less thermal energy than is required during the manufacture of conventional foams. Furthermore, whereas known inorganic foam particles expand relatively slowly, the inorganic foam particles of the present invention tend to expand rapidly, requiring the amorphous residue particles to be maintained at the foaming temperature for an extended period of time. It is easy to manufacture. By heat treatment, the inorganic foam particles of the present invention generally have a diameter of 1.01 to
Expands to about 1.4 times. Although the expansion mechanism of the residual particles of the present invention is not necessarily clear, it is presumed that the expansion occurs through the following mechanism. In other words, the amorphous residue obtained by partial oxidation of coal contains expansion components such as unburned carbon and sulfide sulfur, which are easily gasified by heat treatment. Expand. Furthermore, it is presumed that the amorphous residue has higher activity than natural raw materials such as obsidian, and it is therefore presumed that the above-mentioned vaporized components act effectively even at low temperatures. In addition to the above-mentioned uses, the inorganic foam particles of the present invention can also be effectively used as fillers (agents) for fertilizers, detergents or paints, adsorbents, iron smelting aids, abrasives, filter aids, etc. be able to. Next, Examples and Comparative Examples of the present invention will be shown. Preparation of amorphous residue The residue discharged from a coal gasification furnace using the Texaco method was crushed with a dior crusher, classified, and used. The true specific gravity of this residual particle is 2.72g/
cm ³ , and the melting point was 1320°C. The pulverized amorphous residue particles were classified using a sieve having the openings listed in Table 1, and the content of each particle is listed in Table 1. The proportion of shale used in the comparative example retained in each sieve is also listed in Table 1. The chemical composition of the amorphous residue particles used is listed in Table 2. Note that this residue was confirmed to be amorphous as a result of X-ray diffraction.

[Table] Example 1 100 g of amorphous residue particles of 2.5 mm or smaller prepared as described above were placed in a porcelain evaporating dish and introduced into an electric furnace equipped with an automatic temperature control device using a molybdenum silicide heating element. did. The temperature inside the furnace at the time of introduction is 400
It was warm at ℃. After introducing the amorphous residue particles, the temperature of the furnace was raised to 800°C at a heating rate of 5°C/min, and immediately taken out of the furnace to produce inorganic foam particles. The apparent specific gravity of the obtained inorganic foam particles is 1.71
g/cm ³ , unit volume weight was 0.91 Kg/, 24-hour water absorption was 0.3% by weight, and average crushing strength was 35 Kg.
The chemical composition of the obtained inorganic foam particles is also listed in Table 1. Note that the diameter of the obtained inorganic foam particles was about 1.2 times larger than that of the amorphous residue. The above measurements were carried out using the method and apparatus described below. Furthermore, all measurements in Examples and Comparative Examples shown in the present invention were performed using the following apparatus and method. Measurement method Apparent specific gravity and 24-hour water absorption were measured according to the provisions of JIS-A-1134 and JIS-A-1135. True specific gravity Measured according to the regulations of JIS-R-2205. A measuring cylinder with a unit volume and weight of 100 ml was prepared, particles to be measured (residue and foam) were placed in the measuring cylinder, vibrated a predetermined number of times to a volume of 100 ml, and the weight of the particles was measured. Component Analysis Analysis was conducted according to the method specified in JIS-M-8852. Crushing strength: Measured on 20 specimens using a Kiya hardness tester. Measurement of melting point was carried out according to the method specified in JIS-M-8801.

[Table] Comparative Example 1 In Example 1, instead of the amorphous residue, the third
Shale with the composition shown in the table (true specific gravity 2.56 g/cm ³ , unit volume weight 1.10 Kg/, melting point 1210°C) was used, and inorganic foam particles were produced using the same procedure except that the maximum heat treatment temperature was 1180°C. was manufactured. The unit volume weight of the obtained inorganic foam particles is
The water absorption rate was 0.64Kg/24 hours, 14.9%, and the average crushing strength was 1.8Kg. The chemical composition of the obtained inorganic foam particles is listed in Table 3.

[Table] Examples 2 to 7 and Comparative Examples 2 to 4 In Example 1, the particle size of the amorphous residue particles used, the maximum temperature of the heat treatment, and the temperature increase rate were changed as shown in Table 4. Inorganic foam particles were produced in the same manner except for the following. The unit volume weight, apparent specific gravity, water absorption rate, and crushing strength of the obtained inorganic foam particles are listed in Table 5.

【table】

【table】

[Table] Example 8 0.45 for the amorphous residue particles used in Example 1
The heat treatment was carried out using a rotary kiln with an effective inner diameter of m and a length of 12 m. The temperature at the bottom of the rotary kiln was set at 270°C, the baking point temperature at 750°C, and the residence time of the amorphous residue particles was set at 90 minutes. The unit volume weight, apparent specific gravity, water absorption rate, and crushing strength of the obtained inorganic foam particles are listed in Table 6. Comparative Example 5 In Example 8, instead of the amorphous residue particles,
Using the shale used in Comparative Example 1, the temperature at the bottom of the kiln was 300℃.
Inorganic foam particles were produced in the same manner except that the burning point temperature was 780°C. The unit volume weight, apparent specific gravity, water absorption rate, and crushing strength of the obtained inorganic foam particles are listed in Table 6.

[Table] Comparative example 5 1.03 2.39 5.3 26

Claims (1)

[Claims] 1. Inorganic foam particles containing SiO ₂ , Al ₂ C ₃ , and CaO and having air bubbles inside, wherein the content of SiO ₂ in the inorganic foam forming component is 60% by weight. Below, the content of Al ₂ O ₃ is 20% by weight or more, and CaO
The content of the inorganic foam particles is 5% by weight or more, the unit volume weight of the particles of the inorganic foam is more than 0.6 Kg/ but not more than 1.2 Kg/, and the particle diameter of the inorganic foam particles is 0.5 Inorganic foam particles characterized by being in the range of ~3.5 mm. 2 The inorganic foam particles contain SiO ₂ in the range of 60 to 30% by weight, Al ₂ O ₃ in the range of 20 to 40% by weight, and 5 to 30% by weight.
Inorganic foam particles according to claim 1, characterized in that they contain CaO in the range of 30% by weight. 3 The inorganic foam particles contain CaO, SiO ₂ and Al ₂ O ₃
Claims 1 and 2, characterized in that they contain iron oxide, MgO, Na ₂ O and K ₂ O in addition to the above.
The inorganic foam particles described in any of the following paragraphs. 4 Amorphous residue particles containing combustible components obtained by partial oxidation of coal, which
% of the raw material particles having a particle diameter of 0.6 to 2.5 mm are heat-treated at a temperature of 600°C or higher to expand and foam, and the unit volume weight is more than 0.6 kg/ A method for producing inorganic foam particles having internal air bubbles, the weight of which is 1.2 kg/or less, and the particle diameter is in the range of 0.5 to 3.5 mm. 5. The method for producing inorganic foam particles according to claim 4, characterized in that the amorphous residue particles are heat-treated at 650 to 850°C.