JP2000033356A - Treatment of for making material having possibility containing dioxin free from environmental pollution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To treat a material having possibility contg. dioxin such as residual ash, powdery sludge of paper making or incineration ash of municipal garbage to make it completely free from environmental pollution by melting the material having possibility contg. dioxin by the heat of thermit reaction to convert it into harmless flux. SOLUTION: A rotary feeder 1 is attached to the lower parts of hoppers R, S, T before a furnace as raw material charging hoppers so that a raw material can be automatically fed in a fixed amt. into a graphite crucible furnace 2 surrounded with refractories 3 and provided with a heavy oil burner 4 for melting. In a method for treating residual ash to make it free from environmental pollution by using the graphite crucible furnace 2, the residual ash is converted into a liq. phase by the heat of thermit reaction using the residual ash of an aluminum remelting furnace as a principal material and the contained chlorine and fluorine compds. are pyrolyzed and made harmless. Then, a material having dangerousness contg. dioxin mixed and charged after being dried during the treatment is made harmless by the pyrolysis through the heat of the thermit reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detoxifying a material having a possibility of containing dioxin, such as municipal waste incineration ash, using a melting furnace.

[0002]

2. Description of the Related Art In recent years, the problem of global environmental protection has become a major issue worldwide. In particular, the treatment of industrial waste cannot be an exception.

[0003] Among them, the history of recycling aluminum (hereinafter referred to as Al) is old, and even in Japan, A
The secondary or reclaimed lump (Al alloy lump) regenerated from l-scrap can be produced at an extremely low cost of only 3% compared to the production of new lump (Al ingot). About 35%, that is, annual
At present, about 3 to 5 million tons are supplemented by the regenerated lump, and it is expected that the production of the reclaimed lump will increase with the increase of the used amount in the future.

[0004] The main use of this recycled Al, ie, reclaimed lump, is as an alloy lump, most of which is used for die casting of automobile parts and the like, and is widely used not only for industrial purposes but also widely in general household goods. Have been. FIG. 6 shows a process chart of the production of this regenerated lump,
The residual ash generated by the re-dissolution of ash is generally referred to as residual ash from the symbols 1 to 7 in the figure. Up to ashes.

[0005] The slag (slag) generated in the Al re-dissolving step contains a large amount of metallic components (also called dross), and is subjected to a pulverizing process to recover metal components from the dross. The slag (slag) after collecting the metal is usually referred to as residual ash, and dust generated at that time and dust collected from an automatic ash squeezing machine or the like are also generally referred to as residual ash.

On the other hand, 8,8 generated from the dust collector of the melting furnace
No. 9 is referred to as collected soot ash or black ash, and generally contains a large amount of carbon (soot) and is currently classified as residual ash.

[0007]

There are various types of melting furnaces used in the conventional Al remelting process. In all furnaces except the vacuum melting furnace, molten metallic Al is converted to nitrogen (N) in the air. Reacts with aluminum nitride (Al
N) is produced, and about 10-20% remains in the residual ash as AlN. Therefore, the following reaction proceeds to this residual ash by adding moisture such as moisture in the air at the time of disposal processing or during storage. AlN + 3H ₂ O → Al (OH) ₃ + NH ₃ 2AlN + 3H ₂ O → Al ₂ O ₃ + 2NH ₃

That is, in this reaction, ammonia gas (NH ₃ ), which is a harmful gas, is generated together with a strong odor.
In addition, since this reaction is an exothermic reaction, the temperature rises with the progress of the reaction, and there is a high risk that the combustion of metallic Al contained in the residual ash will occur at the same time, so that these reactions do not proceed. Unless proper processing is performed, the discarding does not remain. As a method of using this residual ash, there was a time when it was often used as a heat insulating agent in the steel industry in the past, but in recent years it has drastically decreased due to a change in the production process of the steel industry, that is, a shift from ingot casting to continuous casting. That is the current situation.

On the other hand, flux is used for the following purposes in melting the recycled scrap (alloy lump) as a main raw material.

That is, (1) a degassing flux for the purpose of removing contained hydrogen gas, (2) a coating flux for the purpose of preventing oxidation at the time of melting, and (3) M as an impurity.
flux for the purpose of removing g, Ca, Na, etc., (4)
Flux for improving the quality of alloy ingot, ・ For grain size adjustment ・ Eutectoid silicon improvement ・ For primary crystal silicon refinement (5) Exothermic debris flux, (6) Furnace wall cleaning flux, etc.

As described above, many fluxes are used in the dissolving step or the subsequent processing step depending on the purpose. Table 1 below shows the main raw materials of these conventional fluxes, and these raw materials are blended according to each purpose to produce a flux. For example, a chlorine compound used as a main component of the flux is mixed with a fluorine compound to lower the melting point of the flux, and also has the effect of mixing metal and Al ₂
It has the effect of improving the wettability with O ₃ and the like, and is frequently used in the flux for Al. Further, fluorine-based flux has an effect of promoting the drying of the slag, and is often used as a cleaning flux.

[0012]

[Table 1]

These fluxes, ie, chlorides and fluorides, are extremely toxic to chlorine compounds or fluorine gas generated during use. Naturally, these compounds are contained in dross together with other oxides, and these compounds are contained in the dross. It remains in the ashes. Al scrap, which is the main raw material of the reclaimed lump, has recently used aluminum as a composite material, that is, Al + plastic type, Al + polyethylene type, Al + vinyl chloride type, etc., and many chemicals have been used. Although not completely elucidated yet, the chlorine compounds contained in these residual ashes are exposed to sunlight, and the photosynthetic reaction progresses, changing to dioxin (polychlorinated dibenzodioxin), the most feared toxic pollution since the Vietnam War. It is reported that the disposal of these residual ashes requires further attention and monitoring of pollution.

In recent years, the production of secondary alloy ingots in Japan is approximately as follows.・ Light pressure products such as plates and extrusions: 2.3 to 2.5 million tons / year ・ Secondary alloy ingots: 1.3 to 1.5 million tons / year ・ Aluminum die-cast products: 700 to 800,000 tons / year ・ Light alloy castings The total is about 500,000 tons / year, etc.

Although the dross generation rate in factories that use new lump such as plates and extruded products as the main raw material is usually as low as about 3 to 5%, it is 20 to 30% in secondary alloy manufacturers that use scrap as the main raw material. It is reasonable to look at the dross incidence rate. However, the dross generation rate varies greatly depending on the melting furnace, melting method, operation method, usage ratio of in-house return materials, etc. at each melting factory, but on average 10-15%
It is reasonable to see that some residual ash has occurred.

That is, in Japan, about 1 to 1.3 million tons of dross are generated annually, of which more than 40% to 50%
Even if collected as ingots, around 500,000 to 600,000 tons of residual ash is generated annually, and although some of it is reused (for the steel and cement industries), most of it is discarded. It is the current situation. The graphite and dust residue ash shown in Fig. 6 contains a large amount of chlorides and fluorides, but the amount generated is about 8000 to 10,000 tons per year. Most of the residue is mixed with the residual ash and discarded. is the current situation.

As described above, the disposal of these residual ash, which involves a great risk of pollution, has many problems in the treatment itself.
For example, at present, waste ash generated in Tokyo and Saitama prefectures is transported and discarded to Fukushima and Fukui prefectures, and the residual ash generated in Aichi prefecture is transported to Mie and Gifu prefectures to some less regulated prefectures. In addition to the re-dissolved maker where residual ash is generated, such as mixing and dumping part of the waste with construction surplus soil, the waste disposal site of the local government or the industrial waste disposal site where individual contractors are licensed At present, it is a major problem, including its processing method.

Therefore, the present invention has been made in view of the above-mentioned various circumstances as described above, and a new material containing a dioxin-containing material such as residual ash, papermaking sludge powder and municipal waste incineration ash has been developed. The purpose of the present invention is to completely detoxify the system and to reuse it as a completely new flux raw material for use in other industries, ie, for steelmaking, steelmaking or high alumina cement.

[0019]

In order to achieve the above-mentioned object, in the present invention, first, a dioxin-containing material is melted by thermit reaction heat to obtain a pollution-free flux. It is characterized by.

The second characteristic is that the material having a possibility of containing dioxin is municipal waste incineration ash.

Third, the material which may contain dioxin is papermaking sludge powder.

Fourth, the melting by thermit reaction heat is a method of rendering a dioxin-containing material pollution-free by thermal decomposition by thermit reaction heat.

Fifthly, the heat of thermite reaction is characterized by utilizing the heat of thermite reaction with the residual ash of the aluminum remelting furnace as a main raw material.

Sixth, the invention is characterized in that a thermite agent is added to a dioxin-containing material.

[0025]

According to the method for detoxifying residual ash according to the present invention,
Thermite reaction heat using the residual ash of the aluminum remelting furnace as a main raw material turns the residual ash into a liquid phase and thermally decomposes the chlorine compound and the fluorine compound contained therein to make it pollution-free. At that time, the heat of combustion of the metallic Al, Si, and Mg components contained in the residual ash also serves as a heat source, and CaO, CaCO ₃ granular powder, SiO ₂ , Mg added during or after the thermite reaction progresses.
O and the like are produced by melting the flux raw material of the target component by arbitrary component control while controlling the temperature.

[0026] Materials having a risk of containing dioxins, such as paper sludge powder or municipal waste incineration ash, mixed and input after drying during the treatment are detoxified by thermal decomposition due to thermite reaction heat and become molten flux. It can be reused or used as flux for other industries by adjusting the component to the target component flux.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.
g from the thermite reaction to remove residual ash from 1800 ° C to 2000
Temperature rise to about ℃ and liquid phase, containing chlorine compound,
The purpose is to make the fluorine compound thermally decomposed to eliminate pollution. At that time, the metallic Al content and Si contained in the residual ash
The heat of combustion is used as the heat source, and the temperature is controlled by adding CaO or CaCO ₃ granules during or after the thermite reaction, and if necessary, SiO ₂ (silica sand) or MgO (dolomite) is added. It is also possible to melt the flux raw material of the target component by controlling the optional components.

FIG. 1 shows a CaO--Al ₂ O ₃ system equilibrium diagram, and FIG. 2 shows a CaO--Al ₂ O ₃ --SiO ₂ ternary equilibrium diagram. The present invention, when manufacturing a CaO-Al ₂ O ₃ based flux material, its manufacture is easily possible by slide into adjusted input material by its component value and the temperature control. Table 3 below shows the target slag composition at the time of smelting clean steel, which is currently the strictest quality as a steel material. The nonmetallic inclusions contained in the molten steel are lifted and removed by the slag in the low melting point region. With the technology, such a component value flux can be easily and inexpensively made possible by the present invention. Table 2 below shows typical component values of commercially available high-alumina cements, which can be produced sufficiently by using the residual ash as a main raw material and adding CaO by the treatment of the present invention.

[0029]

[Table 2]

[0030]

[Table 3]

FIG. 4 shows a schematic diagram of a 1000 kg capacity graphite crucible furnace 2 for general Al melting. In the figure, the hopper R in front of the furnace,
S and T are raw material charging hoppers each having a capacity of 1000 kg. A rotary feeder 1 is attached to the lower part of the hopper, and a fixed amount of raw materials can be automatically supplied to a graphite crucible furnace 2 which is surrounded by a refractory 3 and has a heavy oil burner 4 for melting. Is considered. Pre-furnace hopper R: residual ash A containing 10% or less metallic Al content Furnace hopper S: residual ash containing 15% or less metallic Al B Pre-furnace hopper T: CaO powder (3mm size or less) Representative of residual ash A and B Typical analytical values are shown in Table 3 above.

First, about 50 kg of scrap is put into the graphite crucible furnace 2, the original hot water is dissolved in advance, and about
100 kg of residual ash B is added, and after stirring with the molten metal, 1-2 kg of a commercially available thermite agent (mixture of aluminum powder and iron oxide powder) is added to accelerate the thermite reaction to about 1-2. The temperature rises rapidly in minutes. However, in the treatment of highly active residual ash treated by a Raymond mill, a thermite material is often unnecessary.

Then, the residual ash A was measured while measuring the temperature.
And CaO granules are additionally charged as needed, and raw materials (residual ash and CaO granules) are charged so as to maintain the temperature at about 1600 ° C. At this time, the use of a thermite agent is almost unnecessary except at the time of starting.

Heretofore, it has been general to sprinkle and ignite magnesium or barium carbonate on the thermite agent. However, in the case of the method of the present invention, since the residual ash has a calorific value,
Further, there is almost no necessity because Mg is often contained in the residual ash, and there is almost no need to use a thermite agent thereafter except at the start. That is, when it is desired to increase the temperature, the supply amount of the residual ash B (residual ash having a high metallic Al content) can be increased, or the amount can be compensated for by slightly igniting the melting burner 4. . Further, it can be sufficiently compensated by additional addition of Al foil scrap or aluminum cutting powder.

This operation can be carried out continuously in the rotary furnace 10 (see FIG. 4) or the reverberatory furnace 20 (see FIG. 5). However, in this embodiment, the operation is performed using CaO--Al ₂
In the case of the production example of the O ₃ flux, the following operation is performed using the graphite crucible furnace 2, the details of the use of the raw materials in this operation, the weight of the flux and the like after cooling the tap water, and the The main component analysis value (%) is shown in Table 4 below.

[0036]

[Table 4]

The component values are as shown in Table 4 above, which is an ideal component system as a flux for iron and steel refining. In addition, chlorides, fluorides and the like are not detected, and a completely pollution-free flux (calcium aluminate) It has become. The flux after elution is solid, and can be crushed to an arbitrary size and used according to the required use. In this embodiment, the charging processing amount is about 1200 kg or more in the 1000 kg graphite crucible furnace 2, but the processing of about 1500 kg to 1600 kg / time is possible in terms of capacity.

In this embodiment, the melting process is performed each time in the graphite crucible furnace 2. FIG. 4 shows a general rotary furnace 10 for remelting Al, and FIG. Is shown. In each of the furnaces 10 and 20, a lining brick was made of a refractory for melting Al (chamotte material) by using a high refractory Mg.
By changing to -C type refractory (for steel refining) 30, continuous operation of continuously eluted fluxed molten product, continuously charging and reacting raw materials is enabled, and a large quantity per hour Processing becomes possible.

Also, papermaking sludge or municipal waste incineration ash, etc., which may contain dioxin, are blended and melt-operated to make a non-polluting flux, and the target component flux is adjusted for use as a flux for other industries. Can be done more easily.

[0040]

As described above, according to the present invention, metallic Al, Si, and Mg contained in the residual ash are burned by utilizing the thermite reaction heat with the residual ash of the aluminum remelting furnace as a main raw material. Compounds such as chlorine compounds and fluorine compounds can be thermally decomposed and made pollution-free.

During the treatment, CaO or CaCO ₃ granular powder, SiO ₂ , MgO or the like is added and charged, and a CaO—Al ₂ O ₃ system such as a refining molten flux material for iron making steel or a high alumina cement material is used. CaO-Al ₂ O ₃
—SiO ₂ system, CaO—SiO ₂ —Al ₂ O ₃ —CaF
_It is configured to produce flux of any component such as ₂ system, and the residual ash is completely detoxified by a new method and reused as a completely new flux raw material for other industries, such as for iron and steel making or high alumina cement. The flux raw material of the target component can be arbitrarily obtained by controlling the temperature and the components.

Further, a dioxin-containing material such as dried papermaking sludge powder or municipal waste incineration ash is mixed and introduced, and is made pollution-free by thermal decomposition by thermite reaction heat, and can be reused as a molten flux.

[Brief description of the drawings]

FIG. 1 shows CaO—Al ₂ O ₃ showing one embodiment of the present invention.
It is a system equilibrium state diagram.

FIG. 2 is a ternary equilibrium diagram of a CaO—Al ₂ O ₃ —SiO ₂ system.

FIG. 3 is a schematic explanatory view showing another embodiment of the present invention.

FIG. 4 is a schematic explanatory view showing another embodiment.

FIG. 5 is a schematic explanatory view showing another embodiment.

FIG. 6 is an explanatory diagram showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotary feeder 2 Graphite crucible furnace 3 Refractory 4 Heavy oil burner for melting 10 Rotary furnace 20 Reflection furnace 30 Mg-C refractory R, S, T Furnace hopper

Claims (6)

[Claims] 1. A pollution-free treatment method for a dioxin-containing material by melting a dioxin-containing material by thermit reaction heat to form a pollution-free flux. 2. The pollution-free treatment method for a material containing a dioxin according to claim 1, wherein the material containing a dioxin is municipal waste incineration ash. 3. The method of claim 1, wherein the dioxin-containing material is papermaking sludge powder. 4. The method according to claim 1, wherein the melting by thermit reaction heat is a method of detoxifying a dioxin-containing material by thermal decomposition by thermit reaction heat. Pollution treatment method. 5. The method according to claim 1, wherein the thermite reaction heat is obtained by using thermit reaction heat using the residual ash of the aluminum remelting furnace as a main raw material. Pollution treatment method. 6. The pollution-free treatment method for a dioxin-containing material according to claim 1, wherein a thermite agent is added to the dioxin-containing material.