JPS643821B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a lightweight calcium silicate molded body. Conventionally, methods for manufacturing this type of lightweight calcium silicate molded body include 1) prior to molding, a silicic acid raw material and a lime raw material are boiled and mixed in water to form a slurry containing bulky calcium silicate gel particles, and then molded and autoclaved for curing; 2) Research has been reported aimed at making the product lighter and more heat insulating, such as by creating calcium silicate crystals before molding and drying them immediately after molding. However, each of the conventional methods mentioned above has its advantages and disadvantages.
1) The weight reduction is insufficient with the 2) method, and distortion due to drying shrinkage is likely to occur with the 2) method, resulting in problems with product quality. As a result of intensive research to improve the drawbacks of the conventional techniques, the present inventors have discovered that the most original method 1) involves raising the temperature of the raw material suspension by stirring and heating it in the shortest possible time, and then leaving it to stand still while keeping it warm. When the siliceous raw material and the calcareous raw material are subjected to a gelation reaction in a static state and the entire suspension is made into a gel mass, this gel mass is extremely non-volatile, unlike the slurry containing calcium silicate gel particles obtained by the method 1) above. We have come to the knowledge that the molded product obtained by press molding at the same compressible pressure is strong and easy to handle despite having an extremely high water content, and the final dried product is also extremely low density and lightweight. As a result of further research, we have arrived at the present invention. That is, in the present invention, a raw material suspension mainly composed of a silicic raw material, a calcareous raw material, and a fibrous raw material is rapidly raised in temperature by stirring and heating, and then left to stand at a warm temperature to separate the silicic raw materials and the silicic raw materials in the suspension. The method consists of a first step in which the calcareous raw material is subjected to a stationary gelation reaction and the entire suspension is formed into a gel mass; a second step in which the gel mass obtained in the first step is shaped and dried after autoclaving. A manufacturing method for lightweight calcium silicate molded bodies. A raw material suspension mainly composed of silicic raw materials, calcareous raw materials, and fibrous raw materials is rapidly raised in temperature by stirring and heating, and then kept at a temperature to allow the silicic raw materials and calcareous raw materials in the suspension to separate. When performing a stationary gelation reaction to form the entire suspension into a gel mass, the suspension is
A first step in which silicic raw materials with different degrees of gelation reaction difficulty with calcareous raw materials are prepared and a gel mass is obtained for each suspension; After crushing the gel mass, mix and mold.
A method for producing a lightweight calcium silicate molded body, comprising a second step of drying after autoclave curing. (Hereinafter, the former is referred to as the first law, the latter as the second law, and both laws are collectively referred to as this law). The light weight of this type of calcium silicate molded product is inseparable from how much water retention can be obtained in the molding process. Therefore, with almost no exceptions, conventional weight reduction technologies do not suddenly mold the raw material, but instead stir and heat the raw material suspension to generate a large number of calcium silicate gel particles, which can be called hydrated particles. It was made into a suspended slurry and then press-molded. In this method as well, stirring and heating of the raw material suspension is necessary to bring the entire raw material suspension to the temperature required for the gelation reaction. The gelation reaction is simply a means of uniform temperature rise, and by performing the gelation reaction in a static system with no stirring and no flow, the entire raw material suspension becomes a gel mass with no fluidity, and the gel originally contained in calcium silicate particles is It also includes all free water other than water. Conventionally, the concentration of solids during this silicic acid calcification reaction is such that if the water required for the produced gel and the water necessary for the free movement of the produced gel particles in the liquid coexist, no more water will be added. Because it was meaningless, water was usually added in an amount 10 to 15 times the amount of solid material. However, as is clear from the above, this method does not simply generate calcium silicate gel particles, but instead connects individual gel particles three-dimensionally and further reinforces this gel network with fibrous material. ,
It is important to incorporate free water that coexists in the gaps between these gel networks and make the entire reaction tank into one large gel mass, so the solid concentration in the reaction tank is lower than in the conventional case, It is desirable to add 15 to 30 times the amount of water to the raw material. The gelation temperature, that is, the temperature at which the temperature is left standing in this method is 50
At temperatures below 100°C, only a soft gel mass with a low water content can be obtained; however, in order to reach a temperature above 100°C, a pressure canner is required for heating. Therefore, depending on the reactivity of the silicic acid raw material used, it is preferable that the temperature preservation in this method be carried out at 80 to 90°C. The above-mentioned incubation time at 80 to 90°C is highly dependent on the raw materials, so it cannot be said uniformly, but if it is less than 3 hours, it is insufficient to obtain a gel mass, even if the raw materials have good reactivity, and the reactivity is poor. In the case of raw materials, 15 to 20 hours are required. In addition, those that cannot be formed into a gel mass within 24 hours are unsuitable as raw materials for this method. The silicic acid raw materials used to manufacture this type of calcium silicate molded body have traditionally been natural products with a high silicic acid content such as diatomaceous earth, white clay, silica stone, and clay, as well as various industrial waste materials such as ferrosilicon dust and silica by-product of phosphate ore processing. Waste materials are used, but in many cases, materials other than diatomaceous earth are used in combination due to product quality and cost. In this case, two or more types of silicic acid raw materials are subjected to a gelation reaction together with lime raw materials in the same system, but since the individual silicic acid raw materials have different crystallinity and granularity, and have different reactivity with lime, both Even if average gelation reaction conditions are selected, easily reactive raw materials will overreact (if the gelation reaction exceeds, the strength of the final product will deteriorate), and less reactive raw materials will undergo an insufficient gelation reaction. . In the second method, focusing on this point, each silicic acid raw material is separately gelled under different gelation reaction conditions to form a gel mass, and the gel mass is crushed and then mixed and molded. The weight reduction effect can be maximized. If the gel mass is made too fine in the step of crushing the gel mass, the huge network structure caused by the primary hardening, which is the essence of this method, will be destroyed, so it is difficult to crush the gel mass into appropriate particles. is important. In the first method, it is not necessary to crush the gel mass, and it may be cut into a desired shape and cured in an autoclave, or cut into a suitable weight and size, molded, and cured in an autoclave. However, if this method is to be put to practical use in industrial production, it is best to first transform the gel mass into a fluid state and then transport the gel mass to the molding machine. It has also been found that by adding water and applying it to a crusher to form a granular slurry, it is possible to obtain a molded product that is capable of sufficient liquid transport and maintains light weight. In preparing the raw material suspension in this method,
When a mixed suspension of silicic acid raw materials and lime raw materials is wet-milled for 10 to 30 minutes using a ball mill, etc., it becomes a stronger gel mass, or in other words, a large gel mass that is incompressible during press molding. This can further enhance the effects of this method. At first glance, this grinding effect is thought to be meaningless for fine-particle raw materials, but the finer-particle raw materials have stronger secondary condensation properties, and in reality powders, on the other hand, have larger secondary condensed particles and are therefore less reactive. Even if the particles are of the same size, their surfaces are mechanochemically activated immediately after pulverization. In other words, the operation of wet-milling these reaction raw material powders in the presence of water in advance can be said to be beneficial in promoting the calcium silicate production reaction, strengthening the resulting gel mass, and making it more incompressible. As a result, the molded product has good handling properties despite having a high water retention rate. As this type of calcium silicate molded body, tobermorite type with heat resistance of 650℃ and xonotrite type with heat resistance of 1000℃ have been put into practical use, but when obtaining tobermorite type products using this method, it is the same as the conventional case. The ratio of silicic acid and lime was adjusted to a CaO/SiO ₂ molar ratio of 0.6 to 0.9, and the autoclave curing temperature was adjusted to
The temperature should be 150-180℃. If the purpose is to produce a xonotrite-based product, a material with as little alumina content as possible is selected as the raw material, the CaO/SiO ₂ molar ratio is 0.9 to 1.1, and the autoclave curing temperature is 180 to 220°C. The method described above is useful as a method for obtaining a calcium silicate molded body that is lighter than conventional calcium silicate molded bodies. The present method will be further explained below using Examples and Comparative Examples. Example 1 64 parts of diatomaceous earth (parts by weight), 360 parts of milk of lime with 10% CaO,
After preparing a raw material suspension by mixing 1500 parts of water, 5 parts of asbestos, and 2 parts of wood pulp, steam is blown into this.
The temperature is raised to 80°C in 30 minutes. Thereafter, it was transferred to a gelling reaction tank and left to stand for about 10 hours to obtain a gel mass. Most of this gel mass was crushed while adding water to a diameter of 20 to 30 mm, press-molded, placed in an autoclave, cured for 8 hours at a steam pressure of 8 kg/cm ² (175°C), and dried. and obtained the product. Example 2 A product was obtained in the same manner as in Example 1, except that the gel mass was crushed while adding water to a diameter of about 3 mm or less. Example 3 In Example 1, the heating time of the raw material suspension was 20
A product was obtained by processing in the same manner as in Example 1, except that the mixture was divided into portions. Example 4 In Example 1, the heating time of the raw material suspension was
A product was obtained by processing in the same manner as in Example 1, except that the time was 120 minutes. Example 5 The same procedure was carried out as in Example 1, except that the mixed suspension other than the fibrous raw materials was ground for 20 minutes in a wet ball mill, and then the fibrous raw materials were mixed to prepare the raw material suspension. A product was obtained by processing in the same manner as in Example 1. Comparative Example 1 In Example 1, after preparing the raw material suspension, this
A product was obtained by processing in the same manner as in Example 1, except that the mixture was boiled and mixed for 15 minutes and immediately press-molded without being left to warm. Comparative Example 2 A product was processed in the same manner as in Example 1, except that after preparing the raw material suspension, it was only boiled and mixed for 2 hours and immediately press-molded without being kept warm. I got it. Example 6 64 parts of diatomaceous earth, 25 parts of ferrosilicon dust,
450 parts of milk of lime with 10% CaO, 4.5 parts of alkali-resistant glass fiber
After preparing a raw material suspension by mixing 3 parts of wood pulp, 3 parts of wood pulp, and 2400 parts of water, the mixture was heated to 70°C for 15 minutes.
Steam is blown into the mixture, and then the mixture is kept warm for about 8 hours to obtain a hydrated gel mass. Next, this gel mass is crushed into a granular slurry while adding water to a diameter of 20 to 30 mm, which is press-molded and then molded in an autoclave at a steam pressure of 12 kg/cm ² (190°C) for 10 min.
After time treatment, it was made into a dried product. Example 7 A product was obtained in the same manner as in Example 6, except that the gel mass was crushed while adding water to a diameter of about 3 mm or less. Example 8 A product was obtained in the same manner as in Example 6, except that the gel mass was crushed while adding water so that most of the gel mass had a diameter of 10 to 20 mm. Example 9 The same procedure was carried out as in Example 6, except that the mixed suspension other than the fibrous raw materials was ground for 15 minutes in a wet ball mill, and then the fibrous raw materials were mixed to prepare the raw material suspension. A product was obtained by processing in the same manner as in Example 6. Example 10 64 parts of diatomaceous earth, 360 parts of milk of lime with 10% CaO, 1500 parts of water
After preparing a raw material suspension by mixing 1 part, 3 parts of alkali-resistant glass fiber, and 2 parts of wood pulp, this was heated with steam to a temperature of 80°C for 30 minutes, and then heated to approx.
A hydrated gel mass was obtained by keeping it warm for 10 hours, and the gel mass was further crushed into slurry A with a diameter of 10 to 20 mm while adding water. Separately, 25 parts of ferrosilicon dust, 190 parts of lime milk with 10% CaO, 900 parts of water, 1.5 parts of alkali-resistant glass fiber,
After preparing a raw material suspension by mixing 1 part of wood pulp, this was steam-heated to 70°C for 20 minutes, and then left to stand for about 8 hours to obtain a hydrated gel mass. , while adding water to this gel mass, most of the 10 to 20
The slurry is crushed to a diameter of mm to obtain slurry B. After mixing the slurries A and B, the slurries were molded, autoclaved and dried in the same manner as in Example 6 to obtain a product. Example 11 In preparing both slurries A and B in Example 10, a product was obtained by processing in the same manner as in Example 10, except that both gel lumps were crushed while adding water to a diameter of about 3 mm or less. . Example 12 In preparing both slurries A and B in Example 10, the mixed suspension other than the fibrous raw material was ground for 20 minutes in a wet ball mill, and then the fibrous raw material was mixed to form the raw material suspension. A product was obtained in the same manner as in Example 10, except that . Example 13 In preparing both slurries A and B in Example 11, the mixed suspensions other than the fibrous raw materials were ground in a wet ball mill for 20 minutes, and then the fibrous raw materials were mixed to form the raw material suspensions. A product was obtained in the same manner as in Example 11, except that . Comparative Example 3 In Example 6, after preparing the raw material suspension, this
A product was obtained in the same manner as in Example 6, except that the mixture was boiled and mixed for 30 minutes and immediately press-molded without being left to warm. Comparative Example 4 A product was processed in the same manner as in Example 6, except that after preparing the raw material suspension, it was only boiled and mixed for 2 hours, and then press-molded immediately without being kept warm. I got it. When the density and strength of the products of the above examples and comparative examples were measured and the specific strength was calculated, the following results were obtained. 【table】

Claims (1)

[Scope of Claims] 1. A suspension of raw materials mainly composed of siliceous raw materials, calcareous raw materials, and fibrous raw materials is rapidly raised in temperature by stirring and heating, and then kept at a warm temperature to reduce the silicic acid content in the suspension. It consists of a first step in which the raw material and the calcareous material undergo a static gelation reaction and the entire suspension is formed into a gel mass; a second step in which the gel mass obtained in the first step is molded and dried after autoclaving. A method for producing a lightweight calcium silicate molded body, characterized by: 2. A raw material suspension mainly composed of silicic raw materials, calcareous raw materials, and fibrous raw materials is rapidly raised in temperature by stirring and heating, and then kept warm to separate the silicic raw materials and calcareous raw materials in the suspension. In order to form the entire suspension into a gel mass through a static gelation reaction, the suspension was prepared separately for each silicic material having a different degree of gelation reaction difficulty with the calcareous material, and each suspension was A first step of obtaining a gel mass for each suspension; The gel mass obtained for each suspension in the first step is crushed into small gel masses, and then mixed and molded.
A method for producing a lightweight calcium silicate molded body, comprising a second step of drying after autoclave curing.