JP2002220619A - Recycle treatment process of synthetic resins containing aluminum hydroxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To establish a recycle process of synthetic resins containing aluminum hydroxide, which can utilize the contained aluminum hydroxide and the synthetic resin components. SOLUTION: This treatment process comprises, raising the temperature of the synthetic resins containing aluminum hydroxide, to a temperature range in which the synthetic resins do not burn, reforming the above aluminum hydroxide to alumina through thermal decomposition, and using the reformed synthetic resins in a smelting process or a refining process of a molten metal as an alumina raw material. It is preferable, on that occasion, to crush the above synthetic resins into pieces of 50 mm or less, then to raise the temperature and reform them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recycling an acrylic synthetic resin or a polyester synthetic resin using aluminum hydroxide as a filler material (filling material).

[0002]

2. Description of the Related Art Molded articles made of acrylic synthetic resin or polyester synthetic resin using aluminum hydroxide as a filler material are named artificial marble because of their excellent gloss, strength and durability. Instead, they are used in the fields of wash basins, bathtubs, cooktops and the like, and are also widely used in banks, hotel counters, chandeliers, etc., and their use has been increasing in recent years. Usually, a molded article of synthetic resin using aluminum hydroxide as a filler material (hereinafter also referred to as "artificial marble") is about 50 parts.
~ 55 mass% aluminum hydroxide and about 45-50 mass
% Synthetic resin.

[0003] Waste materials are generated in the process of producing the artificial marble. A part of this waste material is returned to the artificial marble plate production process through the crushing process and the crushing process, and the small size scrap is used as cement fuel, but its usage is limited. . In addition, when this waste material is incinerated in an incinerator or the like, the synthetic resin in the waste material generates a large amount of heat during combustion, damaging the incinerator and causing warming of the atmosphere. Most of the artificial marble waste generated above has been dumped into landfills as industrial waste.

However, artificial marble waste is excellent in durability and extremely difficult to be decomposed. Landfilling and disposal of such waste is not only unfavorable for environmental measures, but landfill disposal is expensive due to the limited disposal site. Disposal costs are required,
Further, from the viewpoint of effective utilization of resources, a method of effectively recycling artificial marble waste has been desired.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to effectively utilize aluminum hydroxide and synthetic resin components contained in synthetic resins containing aluminum hydroxide. It is an object of the present invention to provide a method for recycling aluminum hydroxide-containing synthetic resins.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above problems. First, a morphological change of a molded article such as an acrylic synthetic resin or a polyester synthetic resin containing aluminum hydroxide as a filler material with a rise in temperature was examined by a differential thermal analyzer.

As a result, it was found that when the temperature was raised to about 300 ° C., aluminum hydroxide in these synthetic resins was thermally decomposed, water was removed, and the resin was reformed into alumina (aluminum oxide). In this case, the volume reduction rate with respect to the volume at room temperature was about 25%. Then raise the temperature to 350 ° C
It was found that the combustion of the synthetic resin component occurred before and after. After the burning of the synthetic resin component, the volume reduction rate with respect to the volume at room temperature was about 50%. And it turned out that this residue is mainly composed of alumina.

[0008] That is, it has been found that in synthetic resins called artificial marble, aluminum hydroxide is thermally decomposed before the synthetic resin component burns. Therefore, by maintaining the appropriate temperature by utilizing the difference between the thermal decomposition temperature of aluminum hydroxide to alumina and the combustion temperature of the synthetic resin component,
It has been found that synthetic resins in which the contained aluminum hydroxide is modified into alumina can be obtained.

On the other hand, alumina is widely used as a refractory material, but the refractory material does not require a synthetic resin component and cannot be used as an alumina raw material. It is also possible to recover the residue after burning the synthetic resin component and use it as a refractory material. However, a series of processing costs are added and natural alumina raw materials cannot be opposed in terms of cost.

In the smelting and refining processes of molten metal typified by hot metal and molten steel, the molten metal is reacted with slag to remove impurities such as phosphorus, sulfur and oxygen in the hot metal and molten steel. ing. Normally, quick lime, that is, calcium oxide, which is inexpensive and has an excellent ability to remove impurities, is used as the slag. However, calcium oxide alone has a high melting point and thus has poor reactivity, and the treatment time is prolonged. For this reason, synthetic slag mixed with fluorite or silica stone or prepared in advance so as to lower the melting point is used.
Similarly, when alumina is added to calcium oxide, the melting point of the generated slag is significantly reduced.
Specifically, by adding a small amount of alumina of about 5 mass%,
A low melting point liquid phase having a melting point of about 1540 ° C. is generated, the contact area between the molten metal and the slag is enlarged, and the reaction rate is accelerated.

[0011] That is, in the smelting or refining of molten metal using calcium oxide, the use of the above-mentioned synthetic resin modified into alumina allows the heat of aluminum hydroxide to be added to the molten metal. Without generating a sudden bumping phenomenon accompanying the decomposition, the synthetic resin component burns to promote the generation of molten slag and prevent the temperature of the molten metal or molten slag from dropping, while the alumina component is, for example, molten slag. Has been obtained that it can be used for lowering the melting point of.

In addition, a synthetic resin containing aluminum hydroxide is subjected to a high-temperature smelting furnace or a refining furnace or a molten metal immediately after the previous treatment of the molten metal without subjecting the calcium hydroxide to thermal decomposition treatment. When added to the holding container,
The synthetic resin component burns and the heat of combustion of the synthetic resin component cannot be used to raise the temperature of the molten metal, but at least contributes to raising the temperature of the inner wall of the smelting furnace, refining furnace, or molten metal holding container. On the other hand, it has been found that the alumina component can be used for lowering the melting point of molten slag, for example.

The present invention has been made based on such findings, and the method of recycling aluminum hydroxide-containing synthetic resins according to the first aspect of the present invention is a method of synthesizing aluminum hydroxide-containing synthetic resins. The temperature is raised to a temperature range in which the resins do not burn, the aluminum hydroxide is reformed into alumina by thermal decomposition, and then the modified synthetic resin is converted into an alumina raw material in a smelting process or a refining process of a molten metal. The method for recycling synthetic resins containing aluminum hydroxide according to the second invention is characterized in that the synthetic resins containing aluminum hydroxide are crushed to 50 mm or less in the first invention. And reforming by raising the temperature.

Further, the method for recycling aluminum hydroxide-containing synthetic resins according to the third aspect of the present invention is a method of recycling aluminum hydroxide-containing synthetic resins having a temperature sufficient for the synthetic resins to burn. In a smelting furnace or a smelting furnace or a molten metal holding vessel, the aluminum hydroxide in the synthetic resin is thermally decomposed into alumina and the synthetic resin is burned at the same time. The present invention is characterized in that a molten metal is supplied into a metal holding container, and synthetic resins containing aluminum hydroxide are used as an alumina raw material in a smelting process or a smelting process of the molten metal.

[0015]

Embodiments of the present invention will be described below. First, a first embodiment will be described. Synthetic resins to be recycled in the present embodiment are all synthetic resins containing aluminum hydroxide typified by artificial marble, such as waste materials generated in the manufacturing process of artificial marble and collected and used materials. It is already made artificial marble.

Usually, these synthetic resins containing aluminum hydroxide have a plate thickness of about 5 to 20 mm and a length and width of about 30 to 50 cm for the waste material. On the other hand, in the case of adding auxiliary materials such as slag-making agents in the smelting process or the refining process of the molten metal, it is often added via a hopper or a chute. It is preferable that the crushing is performed until the maximum value of the outer dimensions becomes about 50 mm or less. Also, in the subsequent step of thermal decomposition of aluminum hydroxide, by crushing to such a size, thermal decomposition can be completed in a short time.

Next, the crushed synthetic resin containing aluminum hydroxide is charged into a drying furnace, a heating furnace, or the like, and heated to a temperature range in which the synthetic resin does not burn. Let it break down. Specifically, 30
It is preferable to heat to the range of 0 to 340 ° C. When the heating temperature is lower than 300 ° C., the thermal decomposition of aluminum hydroxide is slow. On the other hand, when the heating temperature is higher than 340 ° C., the synthetic resin component is burned, making it impossible to recycle the synthetic resin component.
However, depending on the synthetic resin component, combustion may not occur even at a temperature exceeding 340 ° C., so that the temperature is not necessarily limited to the above range. The point is that the aluminum hydroxide may be thermally decomposed in the highest temperature range within the temperature range where the synthetic resin component does not burn.

The aluminum hydroxide in the synthetic resin is reformed into alumina by maintaining the temperature within this temperature range for a predetermined time. That is, it is modified into synthetic resins containing alumina. When the thermal decomposition of aluminum hydroxide has sufficiently proceeded, the synthetic resin is taken out from a drying oven, a heating oven, or the like, and cooled to room temperature. Specifically, about 90% or more of aluminum hydroxide may be thermally decomposed. By doing so, it is possible to suppress the sudden bumping phenomenon accompanying the thermal decomposition of aluminum hydroxide when added to the molten metal. The progress of the thermal decomposition of aluminum hydroxide can be grasped by collecting a sample during the heating and analyzing the composition.

The synthetic resin containing alumina thus obtained is used in a smelting process or a smelting process of molten metal represented by hot metal and molten steel.

Specifically, it can be used, for example, for dephosphorizing and desulfurizing hot metal and molten steel. In this case, by adding a synthetic resin containing alumina together with quicklime into a molten metal holding container holding hot metal or molten steel,
A molten slag excellent in desulfurization ability and dephosphorization ability can be quickly produced, and dephosphorization treatment and desulfurization treatment can be efficiently performed. In this case, the amount of alumina added is sufficient if the amount of alumina in the slag is about 5 to 20 mass%. Even this amount of added alumina is sufficient to lower the melting point of quicklime. In addition, since the synthetic resin component burns to generate combustion heat, the combustion heat promotes the generation of molten slag and suppresses a decrease in the temperature of the hot metal or molten steel.

Also, it can be used when melting iron scrap or stainless steel in an electric arc furnace. In the electric arc furnace, slag is formed on the surface of molten steel in order to increase the thermal efficiency of the arc, and the arc is formed in the slag. Also in this case, inexpensive quicklime is used as the main raw material of the slag, and fluorite and the like are used in combination as a melting point regulator of the slag. By adding the above-mentioned synthetic resin containing alumina, fluorite and the like can be obtained. The melting point of the slag can be adjusted without using it. Also in this case, the molten steel and the molten slag are heated by the heat of combustion of the synthetic resin component, and the power consumption can be reduced.

In addition, the present invention can be used in a refining furnace capable of performing arc heating in a ladle such as an ASEA-SKF furnace, a VAD furnace, and an LF furnace. Even in these refining furnaces, molten slag is generated by adding quick lime or synthetic slag etc. in the ladle, and by using the above-mentioned synthetic resin containing alumina together with quick lime, synthetic slag etc. is not used. However, a molten slag having a low melting point and excellent refining properties can be generated.

By treating the synthetic resin containing aluminum hydroxide in this way, the aluminum hydroxide in the synthetic resin is recycled and used as an alumina source for the molten slag in the smelting process of the molten metal and the smelting process. And the recycling of the synthetic resin component as an auxiliary heat source. In this case, since aluminum hydroxide is thermally decomposed and most of it is added as alumina, a sudden bumping phenomenon accompanying the thermal decomposition of aluminum hydroxide when added to the molten metal can be suppressed.
Further, the amount of electric power used for raising the temperature of the molten metal by the heat of combustion of the synthetic resin component can be reduced.

Next, a second embodiment will be described. Synthetic resins to be recycled also in the second embodiment are the same as those in the first embodiment, such as waste materials generated in the process of manufacturing artificial marble, collected and used artificial marble, and the like.

In the present embodiment, as will be described later, synthetic resins containing aluminum hydroxide are directly charged into a smelting furnace or a molten metal holding vessel which does not contain molten metal. At that time, it can be thrown from a mobile bucket or the like without throwing it through a hopper or chute, so if it is the size of waste of artificial marble or collected used artificial marble, etc. It is not necessary to crush it because it can be put in without doing. By omitting the crushing step, the cost of the crushing step can be reduced. However, since the predetermined amount can be quickly and accurately charged by being fed through a hopper or a chute, the maximum value of the outer dimension is about 50 mm as in the first embodiment.
It may be crushed until it is less than about.

Then, the waste material of the artificial marble and the collected used artificial marble, etc., are directly charged into an empty smelting furnace, a smelting furnace, or a molten metal holding container after the previous processing of the molten metal is completed. To use. Since the inner wall surface of the smelting furnace or smelting furnace or the molten metal holding container immediately after the completion of the previous treatment of the molten metal is usually at a high temperature of 500 ° C. or more, the amount of the synthetic resin such as artificial marble and the like contained therein can be reduced. Aluminum hydroxide thermally decomposes to alumina and the synthetic resin component burns. Alumina remains after the combustion of the synthetic resin component, and this alumina is used as an alumina source for molten slag used in smelting or refining of molten metal.

Specifically, for example, the hot metal subjected to the hot metal pretreatment can be used in a ladle for transporting hot metal after the hot metal is supplied to a converter. That is, the synthetic resins containing aluminum hydroxide are burned in the empty hot metal transfer ladle, and alumina remains in the hot metal transfer ladle. Next, in this ladle for transferring hot metal, hot metal is received from the blast furnace, and during hot metal pretreatment of desulfurization or dephosphorization performed thereafter, as described in the first embodiment, The produced alumina acts as a melting point modifier for the added quicklime.

Also, an empty electric arc furnace after tapping,
Ladles used in EA-SKF furnaces, VAD furnaces and LF furnaces can also be used. As described in the first embodiment, in these cases, it is necessary to generate molten slag on molten steel, and alumina brought from synthetic resins containing aluminum hydroxide is used to melt this slag. It can be used as an alumina source for slag.

By treating the synthetic resin containing aluminum hydroxide in this manner, the collected waste material and the used artificial marble are not crushed and the aluminum hydroxide is not thermally decomposed. In addition, aluminum hydroxide in synthetic resins can be recycled as a source of alumina for molten slag in a smelting process of a molten metal or a smelting process. In this case, since the aluminum hydroxide is thermally decomposed into alumina before the molten metal is supplied, a sudden bumping phenomenon accompanying the thermal decomposition of the aluminum hydroxide when added to the molten metal can be suppressed.

The present invention is not limited to the above description, and the present invention is applicable to any type of molten metal as long as it is smelting or refining using slag containing alumina. Can be applied.

[0031]

According to the present invention, it is possible to effectively utilize synthetic resins containing aluminum hydroxide, which have been conventionally dumped in landfills, in the smelting and refining processes of molten metals. It not only saves energy but also contributes to the protection of the natural environment, and has a great industrial effect.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) C21C 1/02 C21C 5/52 5/52 7/10 Z 7/10 B09B 3/00 303E 303A (72) Inventor Chifumi Matsumura 2-9-38 Shosai-cho, Shinminato-shi, Toyama F-term in KK Material Co., Ltd. (reference) 4D004 AA07 AA46 AB03 AC04 BA05 CA23 CA29 CA36 CB04 DA02 DA03 DA11 4F301 AA20 AA25 AB02 CA09 CA33 CA52 CA72 4J002 BG021 CF001 DE146 4K013 BA03 BA05 CB02 CD02 CD07 CE07 CF13 EA00 EA03 EA05 EA09 4K014 AA02 AA03 AB00 AB02 AB03 AB06 AB16 AC01 AD01 AD23 CA04 CB01 CB05

Claims (3)

[Claims] 1. A synthetic resin containing aluminum hydroxide is heated to a temperature range in which the synthetic resin does not burn, and the aluminum hydroxide is reformed into alumina by thermal decomposition. A method for recycling synthetic resins containing aluminum hydroxide, characterized in that the obtained synthetic resins are used as an alumina raw material in a smelting process or a refining process of a molten metal. 2. The synthetic resin containing aluminum hydroxide according to claim 1, wherein the synthetic resin containing aluminum hydroxide is crushed to 50 mm or less and then heated to be reformed. Recycling treatment method. 3. A synthetic resin containing aluminum hydroxide is added to a smelting furnace, a smelting furnace, or a molten metal holding vessel having a temperature sufficient for burning the synthetic resin. The synthetic resin containing aluminum hydroxide is supplied to the smelting furnace or the smelting furnace or the molten metal holding vessel by simultaneously thermally decomposing the aluminum hydroxide into alumina and burning the synthetic resin. A method for recycling synthetic resins containing aluminum hydroxide, characterized in that they are used as alumina raw materials in a smelting process or a refining process of a molten metal.