JP2005041754A - Method for manufacturing foamed glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture foamed glass easily by simplifying additives and lowering the maximum firing temperature, to find a foaming agent so as to reduce the energy consumption and its production conditions, and to manufacture the foamed glass by using, as a raw material, bulb glass which has been hitherto difficult to use as the raw material of the foamed glass. <P>SOLUTION: A mixture is obtained by adding a foaming agent mainly comprising a dolomite powder to powdered glass in an amount of 1-5 wt.% based on the amount of the glass, and then mixing them. The mixture is heated from room temperature to 800-920°C in a time of 30-60 min, and thereafter, rapidly cooled. A foaming agent comprising the dolomite powder or single dolomite may be used as the foaming agent. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a technique for producing a relatively lightweight foam glass that can be used for soil improvement, roadbed burying, rooftop greening, etc., mainly using waste glass.

  Waste glass, especially colored bottle glass, is difficult to recycle as bottle glass or glass except for certain ones because the coloring materials differ depending on the bottle and it is difficult to separate them. It was. Recently, such glass has been foamed to reduce its specific gravity from about 0.2 to 1.2, and the glass components are not eluted, so that slope treatment, greening, roadbed treatment, burial, soil It has been proposed to use it for improvement or rooftop greening.

  As such foamed glass, those called “miracle sol (trade name)”, “super sol (trade name)” and the like are typical, and they are spreading along with a construction method using this. Foamed glass used in these methods is made from bottle glass as a raw material, pulverized, and then added as a foaming agent with at least two types of calcium carbonate, carbon, silicon carbide, borax, etc., usually a combination of several types. These foaming agents are decomposed and gas is generated in accordance with the softening of the glass when the temperature is raised, and the glass is trapped in the glass.

  The manufacturing conditions in this case are, for example, as shown in Patent Document 1, adding calcium carbonate, silicon carbide and borax as a thickener to glass powder, and using a heating furnace from room temperature to about 1000 ° C. When the glass is melted by heating for about 1 hour, foaming by decomposition of silicon carbide and foaming by decomposition of calcium carbonate are performed, and viscosity is increased by borax as a thickener, and these foams are formed. After forming the foamed glass by holding the bubbles in the glass, it is taken out from the heating furnace and rapidly cooled, or it is taken out from the heating furnace and sprayed with water to obtain the foamed glass. I have to.

  As is well known, there are two types of bubbles in the foamed glass produced in this way: open cells and single cells. Which of these bubbles is formed is determined by foaming. The selection is made according to the selection of the agent and the heating conditions. In addition, several conditions have been proposed for the production of foamed glass, and in any case, several kinds of foaming agents are combined mainly with calcium carbonate or carbon.

In the case where the main foaming reaction is performed with calcium carbonate, the decomposition temperature of calcium carbonate is 900 ° C., and therefore a higher temperature, usually 950 ° C. or higher, is necessary. In addition, when carbon powder is used as a foaming agent, it continuously foams from about 800 ° C., but in this case, carbon becomes CO ₂ while partially taking in oxygen of the oxide in the glass as a foaming agent. work. However, since this reaction is not always complete, carbon may remain inside the glass and may be colored black, and it may not be said that foamability is always good, so a combination with other foaming conditions is necessary. is there.

JP-A-11-268930 (page 2-3)

  In the conventional method for producing foamed glass, as described above, the final heating temperature is generally as high as 950 ° C. or higher. Therefore, at such a high temperature, so-called soda glass such as bottle glass and soda lime glass are inevitably low in viscosity. It becomes too much and it becomes difficult to hold bubbles. Therefore, it was generally necessary to add a thickener except under special conditions. In this case, borax is usually added as a thickener, but this alone is insufficient depending on the type of glass, and foam glass may not be obtained with these combinations.

  That is, the main foaming reaction depends on calcium carbonate, but its decomposition temperature is 900 ° C., so the heating temperature in the firing step needs to be 950 ° C. or higher, and it is also a thickener for ordinary glass types. Is essential. In addition, it is necessary to add a plurality of components such as adding other foaming agents. Furthermore, there is a problem that not only the adjustment is required, but also expensive borax must be added. In addition, the high firing temperature also has the problem of consuming excess energy.

  On the other hand, in the case of tube glass such as fluorescent lamps, the soda content is about 3% higher than that of bottle glass, so not only does the softening temperature decrease by about 30 ° C, but the viscosity decreases rapidly above the softening temperature, so borax is added. However, it was almost impossible to produce foamed glass, especially foamed glass having open cells. Further, when carbon is used as a main foaming agent, there is a problem that foaming is hardly obtained even at a maximum temperature of about 900 ° C.

  The present invention has been made in order to solve such problems, and it is possible to easily produce foamed glass by simplifying the additive and lowering the maximum firing temperature, and reducing the energy consumption. It is an object of the present invention to find a foaming agent and its production conditions so that it can be reduced, and to make it possible to produce foamed glass from tube glass that has been very difficult in the past.

  The method for producing foamed glass of the present invention comprises a mixture formed by mixing 1% by weight to 5% by weight of the weight of the glass powder with a foaming agent mainly composed of dolomite powder with respect to the glass powder at room temperature over 30 to 60 minutes. To 800 ° C. to 920 ° C. and then cooled rapidly. Since the foaming agent may be a foaming agent made of dolomite powder or a simple dolomite, the additive can be greatly simplified, and the heating temperature can be reduced by 50 ° C. to 100 ° C. compared to the conventional production method, Energy saving can be achieved.

  This is because the decomposition temperature of dolomite is 730 ° C. to 760 ° C. at the initial stage, and partly decomposes at 850 ° C., which is a higher temperature. Although it is liquefied from a temperature as high as ˜100 ° C., the viscosity is further maintained at a relatively high temperature of 50 ° C. to 100 ° C. The present inventors have found that the temperature for the same viscosity after liquefaction is about 100 ° C. lower than that of the bottle glass, and found that they can be covered with the foaming conditions of dolomite.

Details will be described below. As described above, it has been found that dolomite (CaMg (CO ₃ ) ₂ ) decomposes at 730 ° C. to 760 ° C. to generate CO ₂ , that is, foams, but a part of this decomposition reaction occurs at 850 ° C. . The bottle glass of the soda-lime glass that is a foam glass raw material that is usually used at this time has a softening temperature of 730 ° C. as described above, but has a relatively high viscosity so that foaming actually occurs inside the glass. It has been found that a higher temperature of about 50 ° C. to 100 ° C. is necessary to achieve a low state.

  Further, in the case of bottle glass, the foamed state can be left in the inside, that is, foamed at a slightly higher temperature from about 800 ° C., and the viscosity is high enough to leave bubbles in the glass at that time, further 50 ° C. to 100 ° C. The temperature is maintained at a relatively high temperature, that is, approximately 900 ° C. Therefore, if a foaming agent that causes foaming properly in this temperature range is used, foamed glass can be formed.

  Furthermore, if there is a simple foaming agent that meets this requirement, the target foamed glass can be obtained without using complex additives such as a combination of several foaming agents or thickeners. Should be able to form. Then, when this inventor examined the possibility that a foaming agent exists under such conditions, it turned out that the above-mentioned dolomite is the most suitable purpose.

  In the case of a tube glass such as a waste fluorescent tube, the soda-lime glass is the same, but the alkali content is about 3% higher, so the glass softening point is 700 ° C., which is about 30 ° C. lower. Further, in this case, the viscosity is drastically reduced, and the viscosity is lowered at a low temperature. The temperature having the same viscosity range as that of the bottle glass is about 730 ° C to 830 ° C. Also in this case, it can be seen that bubbles are generated in an appropriate temperature range if dolomite is used.

  For these reasons, when producing foamed glass from waste glass, both the bottle glass and bulb glass, which are the largest supply sources, produce foamed glass according to conventional methods by using dolomite as a foaming agent. I can see that

  For foamed glass, open cells or single cells are selected as necessary. For this purpose, the foaming agent may be a simple dolomite, and heating and temperature conditions may be selected. Of course, it can be combined with a small amount of other blowing agents.

  For example, in the case of bottle glass, it is crushed to remove metal and the like and then pulverized to a particle size of about 40 μm. To this, about 2.5 wt% to 5 wt% of dolomite powder as a foaming agent is added and mixed well. Alternatively, dolomite powder may be added and pulverized at the same time during glass pulverization. Then, spread the fully mixed raw material on the belt conveyor of the heating furnace to a thickness of about 20 mm, and continuously increase the temperature from room temperature to about 900 ° C. over 30 to 60 minutes, reaching 900 ° C. After that, it is immediately put out of the furnace without being kept at the same temperature, or it is rapidly cooled by spraying water. This makes it possible to produce foamed glass having single cells.

  In this case, in the heating step, if the heating temperature is slightly lowered, held at that temperature for about 3 minutes and then rapidly cooled, foamed glass having open cells can be produced. Moreover, in addition to 2.5% to 5% by weight of dolomite as a foaming agent, and further adding about 0.5% by weight of borax as a thickener, it is possible to form open cells even under the initial conditions. is there.

  On the other hand, when tube glass such as a waste fluorescent tube or a light bulb is used as a raw material, the pretreatment is pulverized in the same process as in the case of bottle glass, and dolomite is mixed as a foaming agent to form raw glass, which is used as bottle glass. Heating is performed under the same conditions as in. However, in the case of bulb glass, the viscosity tends to be low, so the maximum temperature is about 800 ° C. Thereby, it is possible to form the foamed glass by keeping the gas generated by the decomposition of dolomite in the glass or by leaving the passage of bubbles in the glass.

  And since it is necessary to solidify the glass immediately after foaming, it is taken out into the atmosphere and cooled as it is or by sending cold air, or it is taken out into the atmosphere and immediately cooled by jetting water. The foamed state can be maintained and foamed glass can be produced.

  In addition, although it does not specifically limit regarding the heating furnace and other equipment to be used, since a continuous heating process is important, when using a batch-type heating furnace, the temperature rising rate is fast and the temperature can be stably maintained. It is desirable to be a thing. Moreover, in the case of a continuous heating furnace, it is desirable that the maximum temperature has a function capable of heating up to about 900 ° C to 1000 ° C.

  Here, the amount of the foaming agent to be added is preferably 1% by weight to 7% by weight of the weight of the glass powder, and varies depending on the glass type of the glass to be foamed. Is desirable. If it is less than 1% by weight, foaming may be insufficient, and if it is 6% by weight or more, the foamed state of the resulting glass may become uneven due to rapid foaming. Needless to say, the main foaming agent is dolomite and may be simple, and other foaming agents and additives such as borax as a thickener can be added depending on the purpose.

The following effects were recognized by the present invention.

(1) It was found that foam glass can be produced by slightly changing the temperature conditions and using dolomite plain as the foaming agent.

(2) By adding a little other foaming agent mainly as a foaming agent, the state of the bubbles could be changed even if the heating temperature conditions were the same.

(3) Compared with conventionally used foaming agents mainly composed of calcium carbonate, it was possible to obtain foamed glass at a temperature lower by about 50 ° C. to 100 ° C., and to save energy.

(4) Previously, a heating furnace using a part of high heat-resistant expensive stainless steel was required, but since it became possible to manufacture at a temperature of 920 ° C or less, the price of the material used as the furnace material was reduced. It became possible to plan.

(5) The foaming agent can be simplified and made inexpensive.

(6) By using dolomite as a foaming agent and lowering the heating temperature, it has become possible to easily produce foamed glass using tube glass such as waste fluorescent lamp, which has been considered difficult in the past.

(7) The foaming agent may be a simple dolomite. In this case, mixing with glass becomes easy, and the state of bubbles can be controlled with a few other additives.

Examples of the present invention will be described below, but it goes without saying that the method for producing foam glass according to the present invention is not limited to these examples.

[Example 1] Colored bottle glass cullet was pulverized by a ball mill containing alumina balls to form glass powder having an average particle size of 50 to 60 µm. To this glass powder, commercially available dolomite powder manufactured by Yoshizawa Lime Industry Co., Ltd. was added by 3.5% by weight of the glass powder, and further pulverized and mixed. By mixing and pulverizing for 30 minutes, a mixed fine powder having an average particle size of 40 μm was obtained. The mixed fine powder was flatly stacked on a stainless steel plate so as to have a thickness of about 20 mm, and charged into a muffle furnace.

  Then, this was heated at a rate of temperature increase of about 20 ° C./min. After about 45 minutes, when it reached 900 ° C., it was held for 3 minutes, then removed from the muffle furnace, and the fan wind was blown at room temperature. Cooled down while hitting. The apparent thickness of the foamed glass after cooling was 4 cm to 4.5 cm, and the apparent specific gravity was 0.7 to 0.8. When this foamed glass was immersed in water, it floated for a while, but began to sink gradually, and finally sank. From this, it was found that the bubbles contained in the foamed glass were open cells. It turned out that it became the foam glass which has an open cell by this.

  In the heating step described above, the heating temperature is increased to 920 ° C., and after reaching 920 ° C., it is taken out of the furnace and cooled in the same manner, and has closed cells with an apparent specific gravity of 0.8 to 1.0. It was found that foam glass was formed.

[Example 2] The same glass powder containing a foaming agent as in Example 1 was used. However, the foaming agent was a mixture of 3% by weight of dolomite and 0.5% by weight of borax. About such mixed fine powder, it heated on the same conditions as Example 1, heated up to 520 degreeC, and after reaching temperature 520 degreeC, it took out from the furnace immediately, and cooled rapidly, applying the wind of the electric fan. As a result, a foamed glass having an apparent specific gravity of 0.7 to 1.0 was obtained. The produced glass was foamed glass having closed cells.

[Example 3] Using waste bottle glass as a glass raw material, this waste bottle glass was pulverized in the same manner as in Example 1, then dolomite powder was added and further pulverized and mixed, and mixed with an average particle size of 50 μm to 100 μm A fine powder was obtained. This mixed powder was spread on a conveyor of a test continuous tunnel furnace so as to have a thickness of about 20 mm and heated.

  In this heating step, the temperature is first raised from room temperature to 750 ° C. at a temperature rising temperature of 25 ° C./min, then held at 750 ° C. for 15 minutes, and then reheated to 900 ° C. at a temperature rising rate of 30 ° C./min. Heated, then removed from the furnace and cooled in air. By taking such a process, it was possible to obtain foamed glass having open cells having an apparent specific gravity of 0.8 to 1.0.

  The foamed glass production method of the present invention can be widely used in the technical field of producing foamed glass used for soil improvement materials, roadbed burying materials, rooftop greening materials, etc., using waste glass as a raw material.

Claims (7)

  A mixture formed by mixing 1% to 5% by weight of the glass powder with a foaming agent composed of dolomite powder to the glass powder is heated from room temperature to 800 ° C to 920 ° C over 30 minutes to 60 minutes, A foamed glass manufacturing method characterized by quenching thereafter.   The method for producing foamed glass according to claim 1, wherein the foaming agent is dolomite plain.   The method for producing foam glass according to claim 1, wherein the foaming agent is a mixture of the dolomite powder and at least one of carbon, silicon carbide, calcium carbonate, and borax.   The method for producing foamed glass according to claim 1, wherein the glass powder is formed by pulverizing waste bottle glass, and the maximum heating temperature is 920 ° C or lower.   The method for producing foamed glass according to claim 1, wherein the glass powder is formed by pulverizing waste tube bulb glass, and the maximum heating temperature is 800C to 870C.   The method for producing foamed glass according to claim 1, wherein the rapid cooling is performed after heating and taking out of the furnace.   The method for producing foamed glass according to claim 1, wherein the rapid cooling is performed by heating outside the furnace after heating and water cooling by water immersion or water spraying.