JPS6348833B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an inorganic porous body used for sound absorbing materials and the like. Inorganic porous materials are manufactured using a wide variety of materials and methods depending on their use and purpose, but there are some that meet the characteristics of strength, water resistance, weight, sound absorption, etc. depending on the purpose, and at the same time are inexpensive to manufacture. It is required to be inexpensive. However, conventional methods for producing inorganic porous materials include crushing and classifying inorganic materials such as ceramics and porcelain, adding a flux, shaping, and then firing and sintering, or granulating inorganic powder, This method involves firing the aggregate into aggregate, classifying it, adding a flux to the aggregate, shaping it, and firing and sintering it again. Both methods require large equipment costs, fuel costs, and man-hours, and the manufacturing cost is high. It had the disadvantage of being expensive. There is also a method of manufacturing a porous body by adding an inorganic binder such as cement or water glass to the aggregate obtained by the above method, molding and hardening, but this method has the disadvantage of low mechanical strength and water resistance. It was hot. The present invention eliminates the above-mentioned drawbacks and also eliminates inorganic wastes such as coal ash and silica sand, which are generated in large quantities from various industries and which are difficult to dispose of, and organic wastes such as pulverized coal, sawdust, and plastic powder. This method was developed for the purpose of producing an inorganic porous material that can be disposed of and effectively utilized.After granulating raw material powder, which is a mixture of inorganic powder and combustible powder, a fluxing agent is added to the granulated material. are added and mixed and molded into a desired shape, and then the molded product is fired to burn off the combustible powder in the granules, thereby converting each granule into porous granules in which inorganic powder is sintered. The method is characterized in that each porous particulate material is bonded with the fluxing agent in a state in which fine communicating slits are formed between each other.Examples of the present invention will be illustrated below. This will be explained in detail using a flow sheet. 1 is a main raw material silo, the main raw material silo 1
In the main raw material inorganic powder, for example, sludge powder containing a large amount of inorganic matter is stored. In the secondary raw material silo 2, combustible powder such as pulverized coal is stored. I'll keep it. 3 is a classifier that classifies the inorganic powder supplied from the main raw material silo 1, and the sludge powder stored in the main raw material silo 1 is classified by the classifier 3 into coarse powder with a predetermined particle size, for example, 88μ or more.
A coarse powder silo 4 and a fine powder silo 5 are classified into two types of fine powder of 88μ or less and are arranged in parallel with the auxiliary raw material silo 2.
is stored in Then, the amount of combustible matter contained in the coarse powder in coarse powder silo 4, the fine powder in fine powder silo 5, and the pulverized coal in auxiliary material silo 2 was measured, and consideration was given from both the granulation and combustion perspectives. The ratio is set using the mixing ratio setting device 6 so that the optimum mixing ratio can be obtained, and the coarse powder, fine powder, and pulverized coal are quantitatively fed into the mixer 8 from the weighing device 7 according to the ratio. Accordingly, the amount of combustible material in the raw material powder, which is a mixture of coarse and fine sludge powder as inorganic powder and pulverized coal as combustible powder, is adjusted to a predetermined ratio, for example, 5 to 10% by weight. Next, this mixed and adjusted raw material powder is supplied with water by a water supply machine 9 and humidified and kneaded by a humidifying kneader 10 such as a pug mixer so that the water content becomes 5 to 20% by weight, and primary aggregation for granulation is performed. Then, in order to increase the granulation strength, a predetermined proportion, for example, 2 to 5%, of an organic binder is supplied to the raw material powder from an organic binder silo 11, followed by a granulator 12 such as a pan-type pelletizer. The product is humidified and granulated to obtain a granulated product with a moisture content of 10 to 25% by weight and a particle size of 0.3 to 20 mm. Next, a predetermined proportion of the bulk volume of the granules classified into a predetermined particle size by the classifier 13, e.g.
A flux of 0.1 to 0.6 g/cc is supplied from the flux silo 14, and the surface of the granules (A) is sufficiently coated with the flux by the coating machine 15 to obtain granules. Next, the above described flux is coated inside the sintering cart 20 of a downward suction type sintering furnace in which a box-shaped sintering cart 20 having a grate 19 at the bottom moves over a number of window boxes 21. The resulting granules are stacked to a thickness of 200 to 500 mm and molded into a desired shape using a molding machine 16. Next, the sintering cart 20 on which the molded product is mounted is guided to the ignition chamber 18 by the drive device 22, the surface of the molded product is initially ignited by the ignition burner 23, and further, while the molded product is transferred from the ignition chamber 18, If the combustible powder in each granule constituting the molded product is self-combusted by suctioning downward at 50 to 150 mmAq from the wind box 21 using the exhaust gas fan 24, the combustible powder will be burnt out and the granule will be removed. The inorganic powder inside is sintered into porous granules, and at the same time, the flux that is in the molded product and melted by the combustion connects each porous granule with fine communicating slits between them. The products are combined to form the product, and then transferred from the sintering cart 20 by the transfer device 25 and stored. In addition,
The conditions necessary for the firing include temperature, for example.
The temperature is maintained at 1,100 to 1,300℃ for several minutes, and high-temperature hot air is flowed downward to dry the granules in the lower layer.Then, the granules are ignited and the combustion position is sequentially moved downward, until the combustion position is on fire. When the surface of the grid 19 is reached, all layers of the molded product in the sintering cart 20 are sintered. In addition, the inorganic powder that is the main raw material in the present invention may be one that contains almost no combustible materials such as alumina, clay, silica sand, etc., or various sludge powders such as water sludge and sewage sludge, and unburned powders such as coal ash. It may also contain some carbon or organic matter,
On the other hand, combustible powders that serve as auxiliary raw materials include sawdust,
Any combustible material such as pulverized coal, plastic powder, or organic binder may be used.Furthermore, in the case where combustible powder is sintered by self-combustion as described above, the amount of combustible powder in the raw material powder is preferably 5 to 15% by weight. This is because if the combustible powder content is less than 5% by weight, the energy required for sintering may be insufficient and the strength of the porous body may decrease.
If it exceeds 15% by weight, it will be difficult to control the sintering temperature, and the temperature will rise and the granules will melt, causing greater shrinkage of the porous body and easily causing deformation and cracking.
If the combustible powder content is less than 5% by weight, it is preferable to sinter it in a sintering furnace with a heat source such as a gas kiln. Sintering in a furnace is preferred. Furthermore, in the above example, after mixing the sludge with fine powder, the difference between the particle size of the sludge powder and the amount of combustible powder is that the coarse powder generally has a large amount of combustible material, and the fine powder has a large amount of combustible material. This is because it is easier to granulate the sludge when the fine powder and coarse powder are appropriately mixed, and it is convenient to adjust both the amount of combustible powder and the granulation properties. Depending on the particle size of the sludge powder, it may be sufficient to simply cut particles below or above a predetermined particle size, or it may be used as is. In addition, in order to have enough granulation strength that the granules do not easily break during granulation and drying,
For example, the required amount of organic binder such as CMC or PVA can be added or coated on the surface of the granules, and this organic binder has the effect of improving the adhesion of the flux to the surface of the granules. There is also. Further, the flux used in the present invention is natural glass such as obsidian or rosinite, artificial glass, glaze, etc., and the melting temperature is preferably 100°C or more lower than the sintering temperature. If it is less than 0.1 g/cc based on the bulk volume of the grains, the porous fired products will not be sufficiently connected to each other and the strength of the porous body will decrease, and if it is more than 0.6 g/cc, the porous fired products will Since the voids are filled and the porosity decreases, it is preferably about 0.1 to 0.6 g/cc. Furthermore, the granules are molded by a pressure method, a vibration method, etc., but the shape of the molded product can be changed to any shape such as a flat plate, a box shape, or a corrugated shape by changing the shape of the sintering cart or mold. The bulk specific gravity and porosity of the product can be adjusted as desired by changing the particle size of the granules, the amount of flux added, molding conditions, etc. Instead of forming a single layer, the granules may be divided by particle size, specific gravity, etc., and each layer may be composited and molded. Next, the firing in the present invention involves a step of burning the combustible powder in the granules constituting the molded product, a step of sintering the inorganic powder to form porous granules, and a step of converting the porous granules with a flux. and the combining step may be carried out continuously in a single furnace or in stages in multiple furnaces;
Further, the sintering temperature needs to be higher than the burnout temperature of the combustible powder and the melting temperature of the flux, and lower than the temperature at which the inorganic powder melts and softens. In addition,
In order to adjust the combustion characteristics, the granulated product may be made into a multi-layered granulated product consisting of layers having different contents of combustible powder, or a combustible material may be mixed into the flux. As is clear from the above description, the present invention involves obtaining granules using raw material powder prepared by adding combustible powder to inorganic powder, and then forming the granules into a desired shape by adding a flux without firing them. By the one-time firing carried out after this molding, the granules constituting the molded product are sintered into porous granules, and communicating pores are formed between each porous granule with a flux. This method aims to obtain an inorganic porous material by bonding in a state of The product obtained by the method of the invention is lightweight due to the porous particles having countless air bubbles and the communicating pores formed between each porous particle, and is easy to handle, strong, and waterproof. Furthermore, inorganic wastes such as coal ash and silica sand, which are generated in large quantities from various industries and have difficulty in processing and disposing of, can be used as inorganic powder as the main raw material, and as a secondary material. Organic wastes such as pulverized coal and sawdust can be used as raw materials for combustible powder, making it possible to dispose of and effectively utilize waste materials.Since the product is a highly strong porous material, it has excellent sound absorption properties. Coupled with the advantage of having a wide range of uses such as wood, fireproofing material, insulation material, and building material, it is extremely useful in industry. Example 1 Clean water sludge powder containing some combustibles obtained from a clean water sludge treatment equipment was used as an inorganic powder as the main raw material, and pulverized coal and CMC were added as combustible powders. A raw material powder with a combustible content of 5 to 15% by weight was prepared, and then water was added to the raw material powder to adjust the water content to 15%, and the mixture was granulated using a pan-type pelletizer into granules with a diameter of 0.3 to 10 mm.
Then, 0.1 to 0.6 to the bulk volume of this granulate
g/cc of glaze is added as a flux and coated, and the granules coated with this flux are placed in a 300 mm rectangular sintering cart in a downward absorption type sintering furnace.
The material is filled and molded to a thickness of 1,000 ml, and the surface is preheated with an ignition burner for about 3 minutes to ignite it, and then, while it is being transferred from the ignition chamber, it is ventilated while suctioning downward at 50 to 100 mmAq with an exhaust gas fan from a wind box. Sintered by self-combustion at 1100-1300 °C for about 10 minutes. The characteristics of the five types of inorganic porous bodies thus obtained are as described in Samples No. 1 to No. 5 in the table. Example 2 A product was manufactured using two types of raw material powders, which were prepared by adding pulverized coal as a combustible powder and a trace amount of CMC to the same inorganic powder as in Example 1 to adjust the amount of combustibles to 2% by weight and 20% by weight. The granulated material, which has been granulated and coated with a fluxing agent, is placed in a fireproof mold with a thickness of 100 mm.
The material was molded into a shape, placed in a furnace equipped with a heating source and a temperature control device, and sintered at a temperature of 1200°C. The properties of the two types of inorganic porous bodies thus obtained are as described in Samples No. 6 and No. 7 in the table. Example 3 Particle size 44μ obtained by classifying coal ash containing unburned carbon collected by a dust collector of a coal-fired boiler
The amount of unburned carbon is 5.5% by mixing and adjusting fine coal ash powder with an unburned carbon content of 5% or less and coarse coal ash powder with a particle size of 44μ or more and an unburned carbon content of 5 to 18%. An 8.0% raw powder was obtained. This raw material powder is humidified and kneaded using a pug mixer, and then humidified and granulated using a pan-shaped pelletizer to obtain a granulated product with a moisture content of 15 to 30% and a particle size of 2 to 20 mmφ.The bulk volume of the granulated product is 0.3 g/ A glaze of cc was added as a fluxing agent to obtain a granulated product whose surface was coated with a fluxing agent. The granules were molded into a sintering cart of a downward suction type sintering furnace to a thickness of 200 mm, the surface was preheated with an ignition burner for about 2 minutes, and ignited. 100mm downward by exhaust gas fan
The material was sintered by self-combustion at 1100 to 1300°C for about 10 minutes under suction and aeration with Aq. The properties of the two types of inorganic porous materials obtained in this way are No. 1 in the table.
As stated in 8. No.9. For reference, raw material powder prepared by mixing combustible powder with inorganic powder is granulated and then fired in a rotary kiln to form porous aggregate.Fluxing agent is added to this aggregate and molded into the desired shape. The molded product was fired again to form an inorganic porous body, and its properties are listed as Reference Example No. 10 in the table. According to the table below, samples No. 1 to No. 9 using the method of the present invention
Sample No. 10, which is a reference example, is very similar in its characteristics. However, although it is not indicated, the maximum amount of heavy oil required to manufacture the inorganic porous materials of Samples No. 1 to No. 9 is approximately 150 per ^m3 of porous material.
On the other hand, in order to manufacture the inorganic porous body of the reference example of sample No. 10, the amount of heavy oil used was approximately 300 ml because the firing process was performed twice, and the method of the present invention used less fuel than the reference example. It can be reduced to less than 1/2,
It has the advantage of being able to manufacture high-quality products at low cost. 【table】

[Brief explanation of the drawing]

The drawing is a flow sheet showing an embodiment of the invention.

Claims (1)

[Claims] 1. After granulating raw material powder prepared by mixing and adjusting combustible powder with inorganic powder, adding and mixing a flux to the granules and molding into a desired shape, then firing this molded product to obtain the granules. The combustible powder inside is burnt out to form each granule into a porous granule in which inorganic powder is sintered, and the flux is used to connect each porous granule with fine communicating slits between them. A method for producing an inorganic porous body characterized by bonding in a formed state.