JPS641411B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for producing sodium silicate and an apparatus therefor. Specifically, the present invention relates to a method and apparatus for easily producing sodium silicate having a molar ratio of alkali to silicic acid (silicic acid/alkali) (hereinafter abbreviated as MR) of 3 or more.

Conventional methods for producing sodium silicate include a wet method in which easily soluble silicic acid raw materials such as clay are heated and reacted together with an alkaline solution (mainly caustic soda solution) in an autoclave, and a method in which silica sand and alkali (mainly soda carbonate) are reacted at 1300 to 1500°C. A dry method is known in which a cullet is formed by heating and melting, and this is further heated and melted in a high-pressure container. However, such conventional methods have the following drawbacks.
In other words, although the wet method requires less energy for production, it has the disadvantage that it is colored due to impurities contained in the silicic acid raw material, has poor filterability, and cannot produce products with a high molar ratio of MR of 2.5 or more. Ta. Of course, if high purity soluble silica such as white carbon or silica gel is used as the silicic acid raw material, it is possible to produce products with a high molar ratio, but these high purity soluble silicas are expensive and are not economically viable. Furthermore, although it is possible to produce a product with a high molar ratio using the dry process, it requires an enormous amount of thermal energy and has the drawback of requiring a huge amount of incidental equipment to improve thermal efficiency. In other words, an industrial method for producing sodium silicate with low energy consumption and a high molar ratio does not yet exist, and there is a strong demand for it in these days of energy conservation.

In order to meet this demand, the inventors of the present invention have made extensive studies and have completed the present invention by discovering that it is sufficient to use a special reaction device to terminate the reaction between an alkali and silicic acid before the reactants transition to a vitrified state.

That is, an object of the present invention is to provide a method for producing high molar ratio sodium silicate with low energy consumption and an apparatus therefor.
A method characterized in that a reactant is separated from a high temperature region before it transitions to a vitrified state, a heat source is installed in a reaction vessel, a reaction plate is arranged around the heat source, and a reaction plate is placed above the reaction vessel. An apparatus for producing sodium silicate is characterized in that a raw material inlet is provided and a reactant outlet is provided at the bottom.

The present invention will be explained in detail below. In the present invention, an alkali-containing substance a as shown in FIG. 3 is used as a raw material.
A silicic acid b raw material coated with is used. Examples of the alkali-containing substance a include sodium metasilicate, sodium orthosilicate, caustic soda, potash, etc. Among these, sodium metasilicate is usually used. Many of these are known as glass raw materials. For example, silicic acid raw materials coated with sodium metasilicate are obtained in a granular state when caustic soda and silica sand are heated to 320 to 450°C, and the surface of the silica sand reacts with the caustic soda. It is something. The reason why such a silicic acid raw material is used is that it is easily melted in the next step and the reaction proceeds easily.

Next, this raw material is heated to 850 to 900°C to cause the alkali-containing substance and silicic acid to react, and the reactant is separated from the high temperature range before it changes to a vitrified state. When transitioning to a vitrified state, the form state, which is a characteristic of the reactant, is lost in proportion to the progress of vitrification, requiring a high-temperature, high-pressure device such as an autoclave for melting, and at the same time, a heat source for this purpose is also required.

The reaction can be carried out, for example, in an apparatus as shown in the drawing. FIG. 1 shows a first embodiment of this device.
is an iron plate type or red brick type reaction vessel, the upper part of which is open as a raw material inlet 13, and a funnel-shaped reactant outlet 2 provided at the center of the lower part. A heat source 3 such as an electric heater or a gas burner is installed near the center inside the reaction vessel 1, reaction plates 4 are arranged in multiple stages around the heat source 3, and a conical plate 5 is provided above the heat source 3. There is a thermometer 1 on the conical plate 5.
4 is inserted. Naturally, the reaction plate 4 and the conical plate 5 are made of refractory material. Of course, it may be made of a metal plate. 6 is a dissolution tank installed below the reactant outlet 2, and a stirrer 7 is provided inside.

Now, the silicic acid raw material 8 coated with an alkali-containing substance, which is charged into such a device by activating the heat source 3 and heating the inside of the device to 850° C. or higher, is charged.
causes a continuous reaction. Upon reaction, the reactant 9 becomes a white foam-like viscous fluid containing many minute bubbles, which naturally falls from the reaction plate 4 in the direction of the arrow due to its own weight and exits the reaction container 1 through the reactant outlet 2. After falling from the reaction plate 4, the next silicic acid raw material 8 reacts and similarly becomes a viscous fluid, and this reactant also falls due to its own weight and is separated from the high temperature region. In other words, upon reaction, it becomes a viscous fluid and is immediately taken out of the system without transitioning to a vitrified state. The reactant 9 released from the reaction vessel enters the dissolution tank 6 filled with water or sodium silicate, where it is heated for 30 minutes while releasing air bubbles.
It turns into powder in about seconds. Falling foam reactant 9
Since it has a heated amount of heat (approximately 850 to 900°C) during the reaction, sodium silicate which is completely dissolved naturally can be obtained by stirring.

Note that FIG. 2 shows a second embodiment of the manufacturing apparatus. In this embodiment, the reaction plate 4 is not provided independently, but a tapered surface 11 is formed on the wall material 10 of the reaction container, and this tapered surface 11 is connected to the reaction plate. It is also used as Note that 14 is a thermometer inserted into the container through the lid 12. The silicic acid raw material is introduced from the raw material inlet 13 between the wall material 10 and the lid 12, reacts with the heat from the heat source 3 while falling along the tapered surface 11, and cracks when exiting from the reactant outlet 2. It becomes a foam-like viscous fluid.

The foam-like viscous fluid obtained by the present invention is a new substance that has never existed before and exhibits an apparent specific gravity of approximately 1.9 when cooled and solidified, and its chemical structure is unclear and must await future research. .

Furthermore, in the present invention, the reactant outlet 2 and the dissolution tank 6 do not necessarily have to be directly connected as in the previously described apparatus. Therefore, depending on the case, melting may be carried out in separate steps. However, it is preferable to connect them directly because the heat possessed by the reactant itself can be utilized in the melting tank 6.

As described above, the present invention relates to a method and an apparatus for producing sodium silicate, which is characterized by reacting silicic acid raw materials and separating the reactants from a high temperature range by their own weight before the reactants shift to a vitrified state. Therefore, the following effects are achieved.

(1) Since the foamed reactant is extremely easily soluble, it is now possible to freely produce sodium silicate with an MR4 or higher, which was previously considered difficult to produce. The reason for this is not clear and will have to wait for future research. Furthermore, the ultra-high molar ratio sodium silicate according to the present invention can be used for special purposes, and it has also become possible to create new uses. Even in conventionally well-known applications, for example, when producing silica gel, the amount of alkali and acid used, which account for a large proportion of the production cost, can be reduced, so the production cost of silica gel can be significantly reduced.

(2) The reaction product of alkali and silicic acid obtained in the present invention easily self-destructs and dissolves in hot water, and the alumina and magnesium contained in the raw materials,
Impurities such as iron can be easily filtered out. Therefore, extremely pure sodium silicate can be produced. Conventionally, melting anhydrous sodium silicate glass required a high-pressure container and a boiler, but the present invention does not require these and can be easily melted.

(3) Conventional dry method does not require high temperatures for the reaction and requires less thermal energy. In particular, in the apparatus of the present invention, the heat source is installed in the center of the container and the raw material is filled around it, so that heat is difficult to escape and the heat efficiency is high. Heat loss due to heat radiation is almost equal to zero.

(4) Since the silicic acid raw material coated with the alkali-containing substance is in the form of granules, the raw materials filled in the reaction vessel move one after another and the reaction progresses naturally. In addition, the raw materials on the reaction plate have a contact angle of 30 to 35 degrees, and the surface that receives heat is wide, and the reaction is carried out in a short time on this surface, making it efficient.

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 Using the apparatus of the second example shown in FIG.
An electric heater was used. First, the electric heater 3 is energized, and when the thermometer 14 reaches 1100°C, the silicic acid raw material 8 coated with sodium metasilicate produced from 1 part by weight of caustic soda and 2.5 parts by weight of silica sand is introduced into the reaction state from the inlet 13. When the mixture was gradually added, the reaction gradually started at about 1/3 of the top of the tapered surface 11 about 5 minutes after the addition, forming a foam-like viscous fluid 9, and then about 2 minutes later, the reaction started at the outlet 2.
The mixture reached this temperature and flowed out of the reaction vessel 1, and was put into the water 15 in the dissolution tank 6 while maintaining the temperature of 900°C, and was pulverized in about 30 seconds while releasing air bubbles in the water. When the powdered product was boiled in a beaker, sodium silicate with an MR of 1:3.1 was obtained which was completely dissolved after about 1 hour.

Example 2 Using the apparatus of the first example shown in FIG.
As a result, kerosene was burned in a burner. When the silicic acid raw material 8 coated with sodium metasilicate produced from 1 part by weight of caustic soda and 2.5 parts by weight of silica sand was introduced from the raw material inlet 13 at the top of the container, when the temperature near the heat source 3 reached approximately 900°C, the reaction plate 4 Above, silicic acid raw material 8
When the temperature reaches about 1100℃, a rapid reaction occurs, and the falling of the foam-like viscous fluid 9 becomes intense.When the temperature reaches about 1200℃, the amount of the viscous fluid 9 falling further increases, but the temperature increases beyond that point. It didn't rise. The temperature of the water 15 in the dissolution tank 6 into which the viscous fluid 9 is dropped rises and maintains its boiling point, and the viscous fluid 9 first becomes powder in the water and is sequentially dissolved, with an MR of 1:3.0.
of sodium silicate was obtained.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the first embodiment of the apparatus of the present invention filled with raw materials, FIG. 2 is a cross-sectional view showing the second embodiment of the same filled with raw materials, and FIG. 3 is a cross-sectional view showing the second embodiment of the apparatus filled with raw materials. FIG. 3 is a cross-sectional view showing the raw materials used. 1... Reaction container, 2... Reactant outlet, 3... Heat source, 4
... Reaction plate, 6... Dissolution tank, 13... Raw material inlet.

Claims (1)

[Claims] 1. Production of sodium silicate, characterized by heating and reacting a silicic acid raw material coated with an alkali-containing substance, and separating the foamed reactant from the high temperature range before it changes to a vitrified state. Law. 2. Production of sodium silicate, characterized in that a heat source is installed in a reaction vessel, a reaction plate is arranged around the heat source, a raw material inlet is provided in the upper part of the reaction vessel, and a foam-shaped reactant outlet is provided in the lower part. Device.