JPH10167783A - Production of artificial aggregate for concrete from incinerated ash and apparatus for production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a detoxicated and densely recrystallized artificial aggregate for a concrete from a refuse incinerated ash or a molten stag of a fly ash. SOLUTION: A slagging material containing MgO is added to an incinerated ash and a fly ash so as to provide the target content within the range of 5-20% MgO in the molten slag or a content extremely approximate thereto before reducing and melting the incinerated ash and fly ash. A pulverized coal 23 and a plastic waste material 24 are then added to the mixed raw material to thereby produce a powdery coke and simultaneously preheat and degas the raw material and reduce a part thereof. The pretreated raw material 7 is reduced and melted to thereby reduce an Fe-based oxide in the raw material into a molten pig iron 5. Elements produced by reducing other heavy metals and reducible oxides are dissolved in the molten pig iron 5. A molten slag 6 having a low gas content without containing heavy metals, etc., is simultaneously produced, then solidified and heat-treated to afford a recrystallized artificial gravel 64 having a dense structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing artificial aggregate for concrete from incinerated ash, and more particularly to incinerated ash produced by incinerating household waste, sewage sludge, industrial waste, and the like. And sewage sludge dry powder, melt and reduce heavy metals and reducible oxides contained in these incineration ash, etc., and produce molten slag mainly composed of mineral substances such as SiO _2. The present invention also relates to a method and an apparatus for producing an artificial aggregate for concrete having a composition very close to natural gravel or natural sand containing as little harmful substances and heavy metals as possible from the molten slag.

[0002]

2. Description of the Related Art Waste and industrial waste from homes are reduced in volume by incineration, and sewage sludge and the like are converted into dry powder. Waste incineration ash and dry powder are usually disposed of in landfills. However, the capacity of dumped land is limited, and efforts are being made to further reduce the volume and recycle resources. In recent years, research has been advanced from the viewpoint of resource recycling, for example, composting and recovery of valuable resources. In addition, attention has been paid to the recycling of building civil engineering materials from the incineration ash of garbage and industrial waste and the molten slag of sewage sludge dry powder. Detoxification treatment is important for such recycling.

When incinerated ash or dry powder (hereinafter collectively referred to as incinerated ash) is melted at 1,500 ° C. or more, combustibles in the incinerated ash burn and dioxins are completely decomposed, and heavy metals are vitreous slag. There are advantages such as being trapped in the inside and reducing the volume of incinerated ash to 1/3 or less. According to such a melting treatment, the inorganic component in the incineration ash also becomes a melt, and when this melt is cooled, it can be turned into a solidified slag.

[0004] Slag is used as a roadbed material or an aggregate for building civil engineering, and is processed into tiles and decorative articles. These recycled products are required to be harmless and have chemical and physical stability.
In recent years, various methods and apparatuses for producing detoxified artificial aggregates by generating molten slag have been proposed. Typical melting methods for incinerated ash include an electric melting method, a fuel combustion melting method, and a direct melting method. The latter two are melted in an oxidizing atmosphere and need not be described. In the former, an electric resistance furnace, a low frequency induction furnace, an arc furnace, a plasma furnace, or the like is used.

In the electric resistance type melting furnace, the incinerated ash is melted by Joule heat generated by applying an electric current to the incinerated ash.
In the low-frequency induction melting furnace, the incinerated ash is melted by contact with molten pig iron heated by the electromagnetic induction of the induction coil. In the arc type melting furnace, the incinerated ash is melted by the heat of the arc generated by the charge between the electrodes. In a plasma melting furnace, incineration ash is melted by a plasma jet composed of high-temperature plasma generated by electric discharge and high-pressure gas.

The main components of slag when incinerated ash are melted are CaO, SiO ₂ , Al ₂ O ₃ , FeO,
MgO. Since FeO and MgO are relatively small, the slag can be regarded as a ternary system of CaO—SiO ₂ —Al ₂ O ₃ . Slags rich in Al ₂ O ₃ have a very high melting point and a high viscosity. Such slag has low fluidity, so that it is difficult to remove the slag from the furnace, and it is not easy to recrystallize. Adding limestone to the slag in an amount that does not increase the slag melting point improves the slag flowability. However, slag with a high content of CaO is easy to digest and does not have long-term chemical-physical stability. Therefore, a slag containing a large amount of CaO is not suitable as an artificial aggregate for concrete requiring high mechanical strength.

On the other hand, the basicity of slag (CaO and SiO ₂
(Weight ratio) is low, the viscosity of the molten slag becomes high, and recrystallization hardly proceeds. If the basicity is high, the slag melting point is high, and the energy consumption for melting is increased. Therefore, when the basicity of the slag in the melting furnace is low, Ca
When O is added and the basicity is high, SiO ₂ is added to adjust the basicity to 0.6 to 1.5.

[0008] Japanese Patent Application Laid-Open Nos. 4-354575 and 4-358584 describe a technique for reducing the melting point of slag in an electric melting furnace and improving the fluidity. The former discloses adding FeO to the molten slag so that the viscosity of the molten slag does not increase when the incinerated ash charged on the molten metal is melted by arc heat. In the latter case, the surface of the molten metal and the surface of the molten slag are made to be in an oxidizing atmosphere, so that F
It discloses generating eO.

According to the above two operations, 5% to 20% of FeO remaining in the slag causes CaO—Si
An O ₂ —Al ₂ O ₃ —FeO system can be formed. The melting point of such slag is reduced and the fluidity of the slag is improved. However, when the molten slag modified into a quaternary system containing FeO is granulated, it becomes a very brittle amorphous granular slag. On the other hand, when the molten slag is gradually cooled,
The FeO in the slag prevents recrystallization of the slag, and the slag becomes a coagulated material having a property and structure significantly different from natural stone. Of course, the slag containing a large amount of FeO cannot satisfy the requirement that the amount of FeO required for securing the toughness of the concrete aggregate is 3% or less.

A slag containing a large amount of heavy metal such as Fe is unstable because the heavy metal is eluted eventually. Such slag is not only harmful, but also cannot recycle metals in the slag. In addition, if the molten slag contains a large amount of FeO, the slag corrodes the hearth of the electric melting furnace and the lining near the slag outlet, shortening the life of the furnace.

The molten slag of incinerated ash will be further described. In stoker-type incinerators and fluidized-bed incinerators, the incineration ash is burned in an atmosphere containing excess oxygen, so that the oxidation reaction is dominant. Therefore, the generated incineration ash is composed of oxides (SiO ₂ , CaO, Al
₂ O ₃ , MgO, FeO, oxides of heavy metals, oxides of harmful impurities As, Bi, etc.). The incineration ash usually contains Cl compounds. When such incinerated ash is melted in an oxidizing atmosphere in a burner furnace, an electric arc furnace, a plasma melting furnace, or the like, the molten slag also maintains an oxide form.

Of course, heavy metals and harmful impurities in the incineration ash are dissolved in the produced slag and remain. This is generally referred to as "heavy metals and harmful impurities are contained in the slag." Since strong oxidizing FeO and Fe ₂ O ₃ existing in the molten slag act as the strongest oxidizing agent in the slag, the slag becomes dirty containing oxides of heavy metals and harmful impurities. Most of such dirty slag is transported to landfills and is not reused. However, heavy metals and harmful impurities will eventually elute from the slag, causing environmental destruction. Heavy metals include Cu, Cr, Ni, Zn, and Pb, and harmful impurities include P, As, Bi, Cd, and Hg.

Attempts have been made to separate FeO from incineration ash using a DC resistance melting furnace. This melting furnace has a structure in which an electrode rod has a positive pole and a furnace bottom has a negative pole. Since Fe ⁺ generated by electrolysis of FeO in the incineration ash moves to the minus pole, it is based on the principle that FeO can be removed from molten slag without using a reducing agent.

However, since the inside of the furnace is not a completely reducing atmosphere, unelectrolyzed FeO remains in the incineration ash, and the molten slag contains 3% to 4% FeO. on the other hand,
Since the molten iron becomes pure iron of 0.03% to 0.05% C, heating at 1,650 ° C. or more is required for tapping. Such melting furnaces require large currents and must be provided with thick electrodes. In addition, the lining is damaged so quickly that continuous operation and a large furnace with a large capacity cannot be realized.

In the prior art for solidifying a molten slag, a treatment for recrystallizing a slag composition as completely as possible is not performed. The solidified slag contains many amorphous parts different from natural stone. This is to add FeO or CaO to improve the fluidity of the molten slag,
This is because SiO ₂ is blended in order to promote the lowering of the slag melting point. Therefore, heat treatment in consideration of the eutectic solidification phenomenon in the multi-phase equilibrium state is impossible. Amorphous (glassy) slag cannot be applied to high-quality artificial aggregate for concrete as a building material, but can only be used as a roadbed material or a material for green farming.

Incidentally, Japanese Patent Application Laid-Open No. 4-139040 discloses an apparatus for casting a slag block by air-cooling molten slag cast in a mold while conveying the slag by a conveyor. However, since it is difficult to control the initial cooling rate when the molten slag contacts the metal surface of the mold, the rapidly cooled slag becomes amorphous and has a directional brittle structure.

[0017]

The incineration ash charged to the melting furnace to produce molten slag is a fine ash aggregated porous material and contains gases, moisture and volatiles. Therefore, before the incineration ash begins to melt, gas and moisture are simultaneously released from the incineration ash, and in addition, volatile substances are burned. As a result, a bumping phenomenon that disturbs the unmelted incinerated ash occurs. Not only is the melting of the incineration ash quiet, but also the continuous charging of the incineration ash is hindered, and continuous automatic operation and automatic control of the melting furnace are hindered.

By the way, in refuse incineration, metal refining, etc., fly ash is collected in a process of treating exhaust gas. When the refuse is incinerated, the amount of incinerated ash / the amount of fly ash is 3/1, and the amount of fly ash cannot be ignored. Fly ash is P
It is a mixture of low-boiling heavy metals b and Zn, salts such as NaCl and KCl, dry lime and lime products used for exhaust gas treatment, and dust. Usually, fly ash is melted for disposal. The molten fly ash treated with the chelating agent is solidified with cement and then landfilled. Although it is possible to recover useful metals and salts from fly ash, they are currently being discarded.

In the treatment of refuse and industrial waste, a large amount of plastic waste is generated. Since plastic waste contains volatile components, disposal is not easy.

Although it is difficult to treat fly ash by itself, it is known that it can be mixed with incinerated ash and melted. When fly ash is added when melting the incinerated ash, the fly ash melts and agglomerates faster than the incinerated ash because the fly ash contains alkali salts and has a lower melting point than the incinerated ash. The molten fly ash layer separated from the incineration ash prevents the gas generated in the furnace from floating, so that the gas accumulated under the layer promotes the bumping phenomenon. Loading fly ash into the melting furnace increasingly hinders the automated operation of slag production plants.

The size of the bumping phenomenon increases as the furnace capacity increases. When the raw material charged in the electric furnace is disturbed by the released gas, the raw material reacts with the oxide in the raw material, and the electrode is greatly consumed. When the vicinity of the tip of the electrode is burned and locally thinned, and the lower end of the electrode falls into the raw material, the arc short-circuits with the dropped electrode. When local heating occurs, operation of the furnace becomes impossible.

If the charge is violently disturbed, the amount of power consumed to produce the molten slag increases and the operating time increases. Since the gas released from the raw material is mixed into the molten slag, air bubbles remain in the solidified slag, and a dense artificial aggregate cannot be obtained.

Incidentally, the particle size distribution of general ready-mixed concrete aggregate is 70% for 25 mm and 30% for 10 mm. In the concrete for civil engineering, 40% is 40% and 20mm is 30%.
%, 10 mm is 30%. Therefore, in order to provide artificial aggregate for use in ready-mixed concrete for building civil engineering, 4 mm to 4 mm
It is desirable to produce slag with a diameter of 0 mm, preferably 5 mm to 25 mm.

In some cases, artificial aggregates similar to natural sands are required for building civil engineering. Japanese Patent Application Laid-Open No. 64-52637 discloses a granulation method in which a water mist is sprayed on molten slag that has been splashed into a rotary hood by rotating blades. JP-A-63-50351 discloses a granulation method in which molten slag dispersed by compressed air is cooled by injection air. JP-A-8-133800 discloses a granulation method in which molten slag is injected into a water-cooled rotating drum.

None of the granulation methods discloses a method for producing a detoxified molten slag which is easily recrystallized. Therefore, the granulated slag becomes amorphous when cooled, and still contains heavy metals and harmful substances.
This artificial aggregate has remarkably different chemical and physical properties from natural sand, and is not suitable as an artificial aggregate for concrete requiring mechanical strength.

A first object of the present invention is to produce an artificial aggregate for concrete by producing a molten slag mainly composed of SiO ₂ or the like having a composition having a low melting point and eutectic solidification as much as possible. It is an object of the present invention to achieve a FeO content of 3% or less, which is a condition of the above, and to produce a dense recrystallized artificial artificial aggregate for concrete having an extremely low gas content.

[0027] The second object is to obtain a clean slag in which the content of harmful substances in the artificial aggregate is reduced as much as possible and chemical safety is enhanced. In addition, it is an object of the present invention to recycle metal resources by separating easily reducible metal components in molten slag.

A third object is to reduce the energy required for recrystallization of the molten slag by reducing the dissipation of the energy input for melting the incineration ash.

A fourth object is to make it possible to reuse fly ash and plastic waste as industrial waste. In addition, by suppressing the occurrence of explosive bumping in the melting furnace, a quiet reduction reaction of the charged raw material has been realized, and automation of an artificial aggregate manufacturing plant that can continuously charge the raw material to the furnace body has been realized. Is to make it possible.

[0030]

SUMMARY OF THE INVENTION The present invention is applied to a method for producing an artificial aggregate from incinerated ash generated by incinerating household waste, sewage sludge, industrial waste, and the like, and molten slag of sewage sludge dry powder. You. The feature is, referring to FIG.
(1) a drying step of heating incinerated ash or fly ash to 120 ° C. to 250 ° C .; (2) weighing the dried incinerated ash or fly ash and a slag-making material containing MgO to produce from these materials 5% to 2% MgO in the molten slag
A mixing step of adjusting the raw material to a predetermined mixing ratio so as to have a target content rate in a range of 0% or a content rate very similar to the target content rate, (3) adding pulverized coal 23 and plastic waste material 24 to the prepared raw material A heating step of preheating and degassing the raw material and reducing a part of the raw material at the same time as generating coke breeze from pulverized coal while maintaining substantially the entire area of the furnace at 700 ° C. to 1,000 ° C. ) The Fe-based oxide in the preheated raw material 7 is melt-reduced to produce molten pig iron 5, and other heavy metals and elements generated by reducing reducible oxides are dissolved in the molten pig iron 5 and A reduction melting step in which a molten slag 6 having an extremely low gas content and containing as little as possible heavy metals and the like is retained and retained at an upper portion of the molten pig iron 5, (5) slag is formed independently of the molten pig iron 5 Molten slag 6 Flowing the mold was conveyed while the plate, the casting process of molding the casting slag 6s during its transport, after release from the mold (6) Casting slag 6s, 4
a crushing step of crushing to a size of from 40 mm to 40 mm, preferably from 5 mm to 25 mm;
u in an atmosphere of 850 ° C. to 1,200 ° C. to recrystallize an amorphous portion remaining in the cast slag grains and remove a residual internal strain of the cast slag grains. In other words, the artificial gravel 64 having a fine structure and recrystallized is produced.

Referring to FIG. 2, the invention according to claim 2 comprises, following the drying step, the blending step, the heating step, and the reduction melting step according to claim 1, (1) discharging independently of the molten pig iron 5; A solidification step of placing the molten slag 6 that has been slag in an air stream to collide with a water cooling wall, and solidifying the molten slag by contact with the water cooling wall to produce a sandy slag 6w; (2) a sandy slag 6w of 85
Rolling in an atmosphere of 0 ° C. to 1,200 ° C. to recrystallize an amorphous portion remaining in the sandy slag and remove residual internal strain of the sandy slag. Thus, the artificial sand 76 having a fine structure is recrystallized.

[0032] The invention according to claim 3 is characterized in that household waste, sewage sludge,
Melt reduction of easily reduced oxides such as Fe, Cr, and P contained in incinerated ash to produce artificial aggregates from incinerated ash generated by incineration of industrial waste and molten slag of sewage sludge dry powder To produce molten pig iron, and to produce a molten slag mainly composed of SiO ₂ etc., which has a composition with the lowest possible melting point and eutectic solidification, from which the gas content is extremely low. For producing a dense recrystallized artificial aggregate for concrete. The feature is that, with reference to FIG. 1, (1) incineration ash and fly ash are kept at 120 ° C.
(2) By weighing the dried incineration ash and fly ash and the slag-making material containing MgO, the MgO in the molten slag generated from these raw materials is 5% to 20%. %, And a mixing step of mixing the raw materials at a predetermined blending ratio so as to have a target content rate or a content rate very close to the target content rate, and (3) a furnace by adding pulverized coal 23 and plastic waste material 24 to the prepared raw materials. 700 ° C to 1,000 ° C for almost the entire body area
And heating the raw material to be reduced and melted at the same time with the preheating and degassing of the raw material and the heating step of reducing a part of the raw material at the same time. That is what we did.

The invention of the apparatus according to claim 4 is applied to an apparatus for producing an artificial aggregate from incinerated ash generated by incinerating household waste, sewage sludge, industrial waste and the like, or molten slag of sewage sludge dry powder. . The feature is that, with reference to FIG. 3 and FIG. 4, (1) incineration ash and fly ash are kept at 120 ° C. to 250 ° C.
Drying apparatus 1A for drying at a temperature of 0 ° C., (2) MgO in molten slag produced from these raw materials by mixing the dried incineration ash and fly ash and the slag-making material containing MgO.
Weighing device 1C for adjusting the raw material to a required mixing ratio so that the target content in the range of 5% to 20% or a content very similar to the target content, (3) the prepared raw material is charged, and By adding pulverized coal and plastic waste material at the position, substantially the entire area of the furnace body is maintained at 700 ° C. to 1,000 ° C., and coke breeze is generated from pulverized coal, while preheating and degassing of the raw material, EK rotary kiln 1D ₁ to a part of the reduction of the raw material, (4)
By reducing and melting the preheated raw material 7, the Fe-based oxide in the raw material 7 is reduced to generate molten pig iron 5, and other heavy metals and reducible oxides are reduced to the molten pig iron 5. Molten slag 6 which has an extremely low gas content and contains as little heavy metals as possible
Melting furnace 2 which produces and stays in the upper part of molten pig iron 5
A, (5) A slag casting apparatus 3A, (6) in which molten slag 6, which has been slagged independently of molten pig iron 5, flows into a mold to be plate-shaped and transported, and solidifies slag during the transport. )
Immediately after the solidified casting slag 6s is released from the mold, 4
a crushing device 3B for crushing to a size of from 40 mm to 40 mm, preferably from 5 mm to 25 mm; A rotary heat treatment furnace 4A for recrystallizing the amorphous portion and removing the residual internal strain of the cast slag grains.

According to the fifth aspect of the present invention, referring to FIGS. 3 and 5, the drying apparatus 1A, the weighing apparatus 1C,
An EK type rotary kiln 1D ₁ and a reduction melting furnace 2A are provided. (1) The molten slag 6 discharged independently of the molten pig iron 5 is caused to collide with a water cooling wall by being put in an airflow and contact with the water cooling wall. Blast slag solidification device 3S that generates sandy slag 6w from molten slag by (2) sandy slag 6w
A rotary heat treatment furnace 4A that rolls in an atmosphere at 50 ° C. to 1,200 ° C. to recrystallize an amorphous portion remaining in the sandy slag and remove residual internal strain of the sandy slag; It is to have.

[0035]

According to the first aspect of the present invention, the reduced melting of incinerated ash and fly ash does not include Fe-based oxides, other heavy metals or reducible oxides, and has a very low gas content. Slag can be obtained. The addition of MgO improves the fluidity of the molten slag and facilitates slag and casting operations. In addition, the melting point of the slag can be reduced without adding CaO excessively. CaO-SiO ₂ -Al ₂ O ₃
The ternary slag is modified into a quaternary system to which MgO is added, thereby expanding the region where the eutectic point of the ternary slag is limited. Therefore, a molten slag which can be eutectic solidified at a temperature as low as possible can be produced.

Since the solidified slag crushed to 4 mm to 40 mm, preferably 5 mm to 25 mm is heat-treated,
The amorphous part completely recrystallizes. The recrystallized slag becomes artificial gravel for concrete that is very similar to natural gravel. This artificial gravel is chemically and physically stable without accompanying digestibility, is detoxified so that heavy metals do not elute, and has high mechanical strength required for artificial aggregate.

Pre-heating, drying and reducing and melting the partially reduced raw material, that the molten slag is immediately solidified,
Since the high-temperature solidified slag is heat-treated, the energy consumed for producing the recrystallized slag is reduced. Since the raw materials can be continuously charged into the melting furnace, the artificial aggregate manufacturing plant can be automated.

Fly ash and plastic waste, which are industrial wastes, can be used as raw materials and heat sources for molten slag. The bumping phenomenon that occurs when fly ash is added to incineration ash,
It can be prevented by heating after drying.

Since the raw materials are melted in a reducing atmosphere,
FeO in the molten slag is extremely small, and the molten slag does not attack the lining near the hearth and the slag port,
Realizes long-term operation of the furnace. The molten pig iron generated by the reduction can be reused as a metal resource.

According to the second aspect of the present invention, CaO-SiO
_Since molten slag capable of eutectic solidification in a quaternary phase equilibrium state of _2- Al ₂ O ₃ -MgO is put in an air stream and collides with a water cooling wall, a sandy slag solidified by contact with the water cooling wall is produced. Can be. When this sandy slag is heat-treated, it becomes artificial sand having the same effect as in the first aspect.

According to the third aspect of the present invention, when producing an artificial aggregate for concrete from incinerated ash or fly ash, the raw material can be dried, preheated, and partially reduced.
If such a pretreatment is applied to the raw material, even if fly ash is mixed into the incinerated ash, quiet reduction and melting in the furnace becomes possible. In addition, fly ash and plastic waste, which are industrial wastes, can be used as raw materials and heat sources for molten slag.

According to the invention of the device of claim 4, according to claim 1,
The same effect as that of the invention is exhibited. In the case of the device of the fifth aspect, the same effect as that of the second aspect can be obtained.

[0043]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method and an apparatus for producing an artificial aggregate for concrete from incinerated ash according to the present invention will be described below in detail with reference to the drawings showing an embodiment thereof.
FIG. 3 and FIG. 4 show an example of a system of an apparatus for producing artificial aggregate from incinerated ash generated by incinerating household waste, sewage sludge, industrial waste, and the like, or molten slag of sewage sludge dry powder.

The main configuration of this apparatus is a pre-treatment facility 1 in which raw materials for artificial aggregate are adjusted so that a desired molten slag can be obtained 1, a melting facility in which the raw materials are reduced and melted to produce a molten slag. 2. It has a slag solidification facility 3 for solidifying the molten slag and a heat treatment facility 4 for heat-treating and recrystallizing the solidified slag.

The pretreatment equipment 1 includes a drying device 1A for drying the raw material for artificial aggregate, a sieving device 1B for selecting a raw material having a predetermined particle size from the dried raw material, and a weighing device for weighing the selected raw materials and adjusting the components. The apparatus 1C includes a heating apparatus 1D for re-drying and partially reducing the raw material whose components have been adjusted.
The treatment equipment is provided with a deodorizing device 1E for drying exhaust gas and an exhaust gas processing device 1F for purifying exhaust gas from the deodorizing device and exhaust gas from the melting equipment.

The melting equipment 2 shown in FIG. 4 employs an electric melting method in which pig iron is generated by reducing and melting a raw material and slag is generated. This melting equipment includes a reduction melting furnace 2A and a raw material supply device 2B that stores the raw material discharged from the heating device 1D and continuously charges the raw material into the melting furnace. Since the reduction of the raw material needs to proceed gently, an electric furnace is preferred. However, in a plasma furnace in which the raw material is greatly stirred by the plasma jet, the reduction of the raw material does not sufficiently proceed even if carbon is added to the raw material. Further, it is difficult to increase the capacity of the plasma furnace. It is preferable to employ any one of an electric resistance furnace, a low frequency induction furnace and an arc furnace as the reduction melting furnace.

In the reduction melting furnace 2A, when the raw material is melted, oxides such as Fe, Cr, and P, which are easily reduced, contained in the raw material are reduced to generate molten pig iron and molten slag. The molten slag has as low a melting point as possible, an extremely low gas content, does not contain harmful substances and heavy metals, and has a composition mainly composed of SiO ₂ or the like which can be eutectic solidified. .

The slag solidification equipment 3 includes a slag casting device 3A for solidifying the molten slag into a plate, a crushing device 3B for crushing the cast slag to a size suitable for artificial aggregate, and a sieve for removing fine slag generated by the crushing. Device 3C.

The heat treatment equipment 4 includes a rotary heat treatment furnace 4A for heating and rolling the crushed cast slag to recrystallize an amorphous portion remaining in the cast slag, and a slag powder from the heat-treated slag. Sieve 4B for removing water and a heat recovery device 4 for recovering the energy possessed by the generated artificial gravel
C. In the rotary heat treatment furnace 4A, the cast slag is recrystallized, and a dense artificial artificial aggregate for concrete having a structure close to natural gravel containing no harmful substances or heavy metals is produced.

Generally, incineration ash as a raw material charged into a reduction melting furnace is extinguished by water sprinkling. for that reason,
Incinerated ash is an aggregated and porous form of fine ash and contains large amounts of moisture, gases and volatiles. On the other hand, dust, that is, fly ash captured from incinerator exhaust gas, is extremely fine. Fly ash is sprayed with water to facilitate transportation and the like, and dust generation is suppressed.

In the fly ash, Cl in the exhaust gas is HCl, KC
1, NaCl, and PbC which is a low boiling chloride
l ₂ (boiling point 950 ° C.), CdCl ₂ (boiling point 960 ° C.), Zn
It exists as Cl ₂ (boiling point 732 ° C.). Furthermore, sulfides are also included in fly ash. Therefore, the alkali content of fly ash is about 1.5% to 2.5%, three to five times that of incinerated ash. Generally, the alkalinity of fly ash is higher than that of incinerated ash, and the melting temperature of fly ash is lower than that of incinerated ash.

When the raw material containing water is charged into the reduction melting furnace 2A as described above, as described in the section of the prior art, before the raw material begins to melt, gas and water are removed from the heated raw material. It is released and the volatiles in the raw materials burn. Since the raw material flows violently due to the rise of the gas and water vapor and the burning of the volatile substances, uniform reduction and melting of the raw material is hindered. Therefore, it is necessary to degas and dehydrate the charged material in advance and to remove volatile substances.

In addition, in order to facilitate recrystallization of the molten slag based on the eutectic solidification phenomenon, Mg in the molten slag is
It is important to adjust the blending of the raw materials so that O has a target content in the range of 5% by weight (hereinafter simply referred to as%) to 20% or a content very similar thereto.

The present inventor has found that prior to melting the raw material, it is necessary to degas the raw material, dehydrate, remove volatile components, and appropriately mix incineration ash, fly ash, and slag-making material in advance. Furthermore, preheating the blended raw materials to a high temperature and simultaneously degassing the raw materials and reducing a part of the raw materials in advance will ensure the generation of molten slag in the reduction melting furnace reliably and quickly. Was found. The above-mentioned pre-processing equipment 1 is provided for performing the above-described processing on the raw material based on these findings.

The pre-processing equipment 1 will be described in detail below. The extinguished incineration ash is stored in the first hopper 11 and the fly ash is stored in the second hopper 12. In addition, the fly ash may be not only the one generated by incineration of refuse but also the fly ash which is generated from another plant such as metal refining and is not easy to dispose. In the present invention, dolomite, lime, olivine or ferronickel smelting slag is used as the slag-making material containing MgO as described later. When it is necessary to dry these slag making materials, they are put into the third hopper 13.

Rotary dryers 1A ₁ , 1A ₂ and 1A ₃ for drying the respective raw materials are provided corresponding to the above hoppers. The drying apparatus 1A heats the raw material to 120 ° C. to 250 ° C. by introducing exhaust gas of 500 ° C. or more from an EK type rotary kiln 1D ₁ and a rotary heat treatment furnace 4A described later.

The raw materials dried by each dryer are sent to the sieving apparatuses 1B ₁ , 1B ₂ and 1B ₃ . The fine raw material that has passed through the sieving apparatus is stored in each of the silos 14, 15, and 16. When calcined dolomite is used as the slag forming is not required dryer 1A _3, in that case, light burnt dolomite is stored directly silo 16. Since the exhaust gas of each dryer has an odor, the exhaust gas is heated at 600 ° C. to 900 ° C. in the deodorizer 1E. The exhaust gas from the deodorizer 1E from which the offensive odor components have been incinerated is purified by the exhaust gas treatment device 1F.

The raw materials that do not pass through each of the sieve devices 1B ₁ , 1B ₂ and 1B ₃ are sent to a sieve 1B _4, and those that have passed through this sieve are crushed by a crusher 17 and stored in a silo 18. Sieve 1B ₄
Is incinerated again in a refuse incinerator (not shown).

Below each silo, weighers 1C ₁ , 1C ₂ , 1C ₃ , 1C ₄ for weighing each dried material are provided. Each weighing device feeds each raw material to the conveyor 19 when producing the molten slag from the raw material so that the MgO in the molten slag has a target content in the range of 5% to 20% or a content very similar thereto. Pay out. This mixed raw material has a required mixing ratio necessary for charging the reduction melting furnace. In other words, CaO-
Preparations are made to obtain a molten slag that enables recrystallization based on a eutectic solidification phenomenon in a quaternary phase equilibrium state of SiO ₂ —Al ₂ O ₃ —MgO.

[0060] downstream of the conveyor 19, EK rotary kiln 1D ₁ for heating the formulated material is placed. This kiln is a furnace for drying, preheating and degassing the raw material and reducing a part of the raw material. EK type rotary kiln 1D
_As shown in FIG. 6, ₁ includes a scoop feeder 20 and an air supply pipe 21 near a material inlet 1D _1i and substantially at the center of the furnace body.

[0061] In the vicinity of the EK rotary kiln 1D _1, pulverized coal feeder 1D ₂ and plastic waste feeder 1D ₃ is provided (see Figure 3). Pulverized coal is a fuel for heating a raw material, and further reduces a part of the raw material. During the reduction reaction, coke breeze required in the next reduction melting step is naturally generated in the EK type rotary kiln.

The plastic waste containing volatile substances becomes a fuel for heating the raw material. If the plastic waste is made finer in advance, it can be easily incinerated with an EK type rotary kiln, and the treatment of industrial waste is also realized. When dolomite is mixed in the silo 16, the lightly fired dolomite is also EK type rotary kiln 1D.
Generated by ₁ .

The EK type rotary kiln 1D ₁ uses a burner 22 (see FIG. 6) to heat the raw material in the same manner as a normal rotary kiln. However, this kiln is different from a normal rotary kiln having a wide low temperature range as shown by a dashed line. Since the pulverized coal 23 and the plastic waste material 24 supplied from the scoop feeder 20 rotating together with the furnace body burn, the temperature distribution in the furnace becomes substantially constant as shown by a two-dot chain line.

The scoop feeder 20 has a pipe structure as shown in FIG. 7, and extends in the radial direction of the furnace body. The pulverized coal 23 and the plastic waste material 24 in the trough 25 installed so as to cover the lower half of the furnace body can be scooped from the opening 20a outside the furnace. The opening 20a
By controlling the opening and closing timing of the valve 20v provided in the vicinity of the above, pulverized coal and the like are charged into the furnace body in a short time. When the valve 20v is closed, combustion of fuel adhering to the inside of the scoop feeder 20 due to hot air entering from the opening 20b inside the furnace is prevented.

Since the air supply pipe 21 is open to the atmosphere, natural air supply is possible if the pressure in the furnace is low. FIG.
As described above, the outside air can be positively supplied by the push-in blower 21a. The valve (not shown) provided on the air supply pipe 21 and the valve 20 of the scoop feeder 20
If the opening of v is adjusted, the inlet 1D _1i to the outlet 1D _1o
Can easily be adjusted to an atmosphere of 700 ° C. to 1,000 ° C.

Next, the reduction melting furnace 2A of the melting equipment 2 will be described in detail. This reduces and melts a high-temperature dried raw material in which coke breeze is mixed. The Fe-based oxide in the incineration ash is reduced, and molten pig iron is generated. Elements generated by reducing other heavy metals and reducible oxides are dissolved in the molten pig iron. Simultaneously with the production of the molten pig iron, a molten slag having an extremely low gas content and containing as little as possible heavy metals is produced. Since the molten slag is light, it stays on top of the molten pig iron.

[0067] The submerged arc DC resistance furnace 2A ₁ as an example of a reduction melting furnace 2A, will be described with reference to FIG. Submerged arc resistance furnaces can be implemented with three-phase or single-phase AC or DC electric furnaces. However, in a three-phase AC electric furnace, the direction of the arc generated between the electrodes is biased, so that only the surface layer on which the raw material is deposited tends to be heated. The generation of a quiet and uniform melting zone, which is required when reducing and melting a powdery or granular material having a low specific gravity and a low electric conductivity, is prevented. On the other hand, in a single-phase AC electric furnace, since the AC power always reciprocates, the heating of the raw material tends to be localized. As a result, it is optimal to apply a DC electric furnace having the simplest furnace structure and easy electric control to the reduction melting furnace. The DC electric furnace can supply electric energy to the raw material most stably by employing a furnace bottom electrode described later.

The submerged arc DC resistance furnace 2A ₁
A plurality of plus electrodes 27 described below are provided inside the furnace wall and the furnace bottom.
And a furnace lid 2b connected to the raw material supply device 2B. The furnace body 2a includes a molten metal reservoir 5A for storing molten pig iron 5 having a large specific gravity, and a molten slag reservoir 6 for retaining the generated molten slag 6 on the molten pig iron 5.
A is a vessel in which A and a raw material storage section 7A for depositing the raw material 7 above the molten slag 6 are secured. Then, the raw material 7 is reduced and melted gently and uniformly over time by the submerged arc electric melting method.

A single negative electrode movable electrode 8 which moves up and down at the center of the furnace lid 2b is arranged. In the furnace body 2a,
A tap hole 5a for intentionally leaving the molten pig iron 5 in the molten metal reservoir 5A and discharging it, and a tap hole 6 for discharging the molten slag 6 retained on the molten pig iron 5 by removing the tap plug 6a.
b.

In the case of intermittent slag discharge, a gas supply hole 6c is provided in the slag plug 6a. By sending an inert gas for stirring the molten slag 6 from the gas supply hole,
It is possible to prevent slag blockage from occurring during reduction melting in the vicinity of the slag port 6b. Since the molten slag 6 and the molten pig iron 5 are completely separated in the furnace, a metal water-cooled gate or a water-cooled jacket (not shown) can be used for the slag port 6b.

The raw material 7 put into the furnace generally has a small content of oxides to be reduced such as Fe-based oxides. Since the consumption of the movable electrode 8 is reduced, it is possible to employ a sodaberg electrode which is easier to operate and cheaper than the artificial graphite electrode. The Seedaberg electrode is a known electrode used for producing ferroalloys and the like, and has a thin iron cylinder and a carbon paste inside. This electrode has a property of being self-baked and solidified by resistance heat when energized. However, in a DC resistance furnace for submerged arc melting,
There is no example of this type of electrode being used.

The inner surface of the cylindrical steel shell 2s of the furnace body 2a is covered with a lining 2m, and a carbon stamping layer 28 is formed on the furnace lining 2m on the lining 2m. Numerous graphite blocks 29 are arranged on the inner surface of the furnace wall and the upper surface of the carbon stamping layer. The furnace lid 2b is provided with a hole at the center where the movable electrode 8 moves up and down, and is provided with a plurality of raw material charging holes 30 opening from the movable electrode 8 at different positions in the radial direction. The raw material 7 can be airtightly and continuously charged from the raw material charging hole by the screw feeder 31 during the furnace operation.

The plus electrode 27 provided on the furnace body 2a is
As shown in FIG. 9A, the shape is L-shaped when viewed from the side of the furnace. This positive electrode is composed of a vertical feeder 27A buried in the furnace wall and a horizontal furnace bottom electrode 27B arranged on the furnace bottom. The power supply 27A is a pure iron bar of 0.02% C.
As shown in FIG. 8, the feeder 27A has a forward path 27m through which the cooling water flows and a return path 27n formed inside the forward path 27m.
Are formed.

A bottom electrode 27 for supplying DC power to the bottom of the furnace
9B, as shown in FIG. 9B, includes a half ring 27a made of pure iron along the steel shell of the furnace body, and a web 27b made of an iron plate extending inward of the half ring. Since the web portion is substantially semicircular in a plan view, as shown in FIG. 10 (a), the two plus electrodes 27, 27 make the entire hearth covered with the carbon stamping layer and the graphite block conductive. Parts can be formed.

At the center of the web portion 27b, a semicircular notch 27r represented by a solid line or a broken line, which is equal to or larger than the diameter of the movable electrode 8 indicated by a virtual line, is formed. A large number of short iron bars 2 are provided on the upper surface of the web 27b.
If 7p is welded, the integrity of the web portion 27b and the carbon stamping layer 28 (see FIG. 8) is enhanced, and the conductivity of the hearth is improved. The semicircular notch 27r suppresses a short circuit of current from the plus electrode 27 to the movable electrode 8, so that the raw material is uniformly heated in a wide area.

The power supply 27A is provided at one end of the furnace bottom electrode 27B as shown in FIG. 9B. When the furnace bottom electrodes 27B, 27B are arranged as shown in FIG. 10 (a), if the two power supply bodies 27A, 27A are close to each other, the tapping operation, the tapping operation, and the maintenance work of the furnace body are not hindered. like,
The flexible conducting wires 32 for power supply can be collected at one place of the furnace wall (see FIG. 8). When the furnace body is large, a one-third or one-quarter furnace bottom electrode (not shown) is employed to facilitate obtaining a uniform conductive region.

Referring to FIG. 8, when the bottom electrode 27B is employed, a wide conductive area is formed in the hearth by the molten pig iron 5, the graphite block 29, and the carbon stamping layer 28 staying in the hearth. When a substantially uniform potential level is formed on the hearth surface in a state where the tip of the movable electrode 8 penetrating the raw material layer is immersed in the molten slag layer, the flow of current becomes conical. The raw material near the conical region is melted by Joule heat. The molten slag 6 in the conical area is heated,
Degassing of slag is also planned. If the voltage is raised by raising the movable electrode 8, the power supply increases, so that the conical current distribution is further expanded.

Due to the conductive action of the coke breeze in the raw material 7 and the heating and melting action of the raw material having low electric conductivity, the raw material having a low specific gravity is thermally reduced efficiently and uniformly.
The forming slag layer 33 is formed on the surface of the melt by the gas generated by the reduction reaction. The arc generated between the electrodes is always covered with the raw material 7 and the forming slag 33 (submerged state). Since the arc is extremely reduced due to the formation of forming slag,
Disruption of the melt by the arc is suppressed.

Since a current flows through the burning coke accumulated on the surface of the forming slag layer 33, the reducing action proceeds quietly and largely on the surface of the forming slag layer covered with the raw material 7. Iron reduced from FeO falls into a hearth as droplets. Such a melting method is different from the “metal electrolysis” method in which the movable electrode is positive and the furnace bottom electrode is negative, so that the movable electrode may be thin. In addition, power transmission efficiency is improved, and power consumption is significantly reduced. It should be noted that the melting method according to the present invention is electric resistance heating, not metal heating or combustion heating in an oxidizing atmosphere.

Incidentally, the vertical power supply 27A connected to the flexible conductive wire 32 contributes to maintaining the reducing atmosphere at the furnace bottom. Assuming that a horizontal power supply provided in place of the vertical power supply 27A extends from the bottom electrode 27B and penetrates the furnace wall, the horizontal power supply is provided by the vertical power supply 27A.
Shorter than If outside air enters between the horizontal power supply and the lining 2m, the reducing atmosphere at the furnace bottom is damaged. Even if air enters between the vertical feeder 27A and the lining 2m, the invading air rises due to the heat of the furnace body,
Intrusion of outside air into the furnace bottom is prevented as much as possible.

The long power supply 27A embedded in the lining 2m of the furnace wall prevents oxidation of the furnace bottom electrode 25B and keeps the life of the plus electrode 27 long. Burnout of the carbon stamping layer 28 is also avoided, and long-term continuous operation of the furnace is realized. The plus electrode 27 does not need to be completely L-shaped, but preferably extends vertically or inclined from the furnace bottom electrode 27B in the lining 2m as long as possible.

Since the hearth is covered with the carbon material, the hearth is kept in a reducing atmosphere. As a result, the molten slag does not corrode the hearth and the lining near the slag outlet. The furnace bottom electrode 27B does not oxidize even at high temperatures. On the other hand, since the power supply 27A may be oxidized when the temperature in the furnace increases, it is water-cooled as described above. Since the positive electrode 27 is connected to the copper Kobel plate 34 disposed around the furnace via the flexible conductive wire 32, a power supply circuit can be formed without being affected by the thermal expansion of the furnace body.

It has already been mentioned that the operation control of a normal DC electric furnace is easier than that of an AC electric furnace. However, in a DC electric furnace, an arc is locally generated as in a single-phase AC electric furnace. The DC electric furnace employing the furnace bottom electrode 27B can realize a uniform reduction and melting process in the furnace due to the good controllability of the operation and the power supply effect covering a wide range of the furnace bottom.

The connection between the power supply 27A and the flexible conductor 32 may be made as shown in FIG. 10B. With the molten solder 35a stored in the iron box 35 welded to the upper end of the power supply 27A, one side of the copper plate 35b connected to the flexible conductive wire 32 is buried. When the solder solidifies, the solder 35a and the power supply 27A are completely adhered to each other, and the conductivity to the positive electrode 27 is increased.

[0085] Returning to FIG. 8, by submerged arc DC resistance furnace 2A ₁ in the raw material 7 is melted, the molten slag 6 is generated. At the same time, the Fe-based oxide in the raw material 7 is reduced in the forming slag layer, and C is reduced to 3.0.
% Of molten pig iron 5 containing 4% to 8% of Si. Other heavy metals Cr, Ni, Co, C contained in the raw material
Elements such as u, Mn, and Mo, as well as elements P, As, and the like generated by reducing reducible P ₂ O ₅ , As oxides, and the like, melt into the hot metal droplets. The molten pig iron drops fall in the forming slag layer and the molten slag layer, and the molten pig iron 5 is stored in the molten metal reservoir 5A. This molten pig iron can be used, for example, as a raw material pig for casting, and the recovery of metal resources from incinerated ash is realized. Since pig iron has a property of depositing carbon when the amount of Si increases, the molten pig iron 5 having high Si does not corrode the graphite block 29 at the furnace bottom.

The molten slag 6 does not contain heavy metals and the like as much as possible, is maintained at about 1,500 ° C., and stays at the upper portion of the molten metal reservoir 5A. If the residence time is sufficiently ensured, the molten slag 6 is defoamed, and the gas content becomes extremely low. Since the molten slag is pure slag, if the slag is solidified, artificial gravel from which heavy metals and harmful substances are not eluted can be obtained.

In the above-mentioned reduction melting operation, SiO ₂ ,
A molten slag containing CaO, Al ₂ O ₃ as a main component, and a target content of MgO in the range of 5% to 20% or a content very similar thereto is produced. This molten slag has a component composition as close as possible to the eutectic point in a quaternary phase equilibrium state of CaO—SiO ₂ —Al ₂ O ₃ —MgO. Since the melting point of the slag is the lowest, the eutectic solidification phenomenon of the molten slag is easily developed. this is,
This means that the ternary slag of CaO—SiO ₂ —Al ₂ O _{3 having} a narrow eutectic point generation region has been modified into a quaternary slag having a wide eutectic point generation region. That is, by adding a predetermined amount of MgO, recrystallization of the molten slag becomes easy even by slow solidification.

Incidentally, the capacity of the reduction melting furnace differs depending on the scale of the refuse incinerator. For example, a large plant that produces 100 tons / day of molten slag may be required, or a small plant of 10 tons / day may be sufficient. Since molten slag is discharged using its height head,
There is no need to input auxiliary materials such as lime. When slag is continuously discharged from a small furnace, the amount of slag is small. However, when the slag is continuously or intermittently discharged from a large furnace or when the slag is intermittently discharged from a small furnace, the amount of slag per minute increases. In such a case, it is necessary to prevent a temperature drop when the molten slag is transferred to the slag solidification facility. on the other hand,
In order to maintain an efficient reduction and melting action, it is desirable to keep the slag level in the reduction and melting furnace. Further, in order to remove slag of even more pure slag, it is preferable to extract slag from the lowermost portion of the molten slag layer.

When it is necessary to satisfy the above requirements,
As shown in FIG. 11, a forehearth 36 connected to the slag outlet 6b is provided. The height of the vessel 36a of this forehearth is set equal to the desired height of the molten slag layer to be kept in the reduction melting furnace 2A. When the molten slag 6 in the reduction melting furnace 2A increases,
The molten slag 6B in the forehearth 36 can overflow. Since the slag port 6b is usually provided at the lowermost portion of the molten slag layer, pure slag containing as little gas as possible is led out to the forehearth 36. Then, two molybdenum rods 37, 37 are inserted into the vessel 36a as heating electrodes to maintain the temperature of the molten slag 6B.

In the case of intermittent slag removal from the forehearth 36, the slag plug 6a indicated by a virtual line may be removed from the slag port 6b, for example, every three hours. If the amount of slag overflowing from the forehearth 36 is too large, the gate 38 provided at the outlet of the vessel 36a is closed. Since the forehearth 36 only needs to have a water cooling wall, it can be easily attached to the steel shell 2s of the reduction melting furnace 2A. Part of the molten slag 6B solidifies on the water cooling wall,
The lining forms naturally. Note that reference numeral 8a in the figure denotes an electrode economizer.

Although the raw material 7 charged into the reduction melting furnace 2A has been dried and heated in advance, a small amount of volatile substances and gas remain in the raw material. When the raw material is reduced and melted, residual gas in the raw material, combustion gas of volatile substances, and CO ₂ generated by the reduction reaction are discharged as furnace exhaust gas. This exhaust gas amount is much smaller than that of the EK type rotary kiln. Since the exhaust gas does not have a bad smell, it is directly sent to the exhaust gas treatment device 1F. The molten fly ash captured by the exhaust gas treatment device has a high concentration and often reaches the level of a cut-off grade having the lowest grade at which valuable mineral products can be economically recovered. This molten fly ash is not returned to the second hopper 12 (see FIG. 3) of the pretreatment facility, and valuable minerals contained therein are separately collected.

Near the reduction melting furnace 2A, the molten slag 6 discharged from the slag port 6b continuously or intermittently every two to three hours is supplied to the slag solidification facility 3 shown in FIG.
Slag receiving gutter 4 to be immediately guided to slag casting device 3A
1 is provided. Slag casting apparatus is for solidifying the molten slag has a recrystallization tends composition while transporting the molten slag 6, a first conveyor 3A ₁ and FIG. 1
Made from the second conveyor 3A ₂ Metropolitan shown in 4.

[0093] The first conveyor 3A ₁ is continuously lined mold 3a as shown in FIG. 12, it includes a 3a, a pan conveyor for forming a plate-shaped continuous solidified slag 6p. FIG.
Second conveyor 3A ₂ of a roller conveyor or pan conveyor gradually cooled to solidify slag 6p encourage partial primary recrystallization based on eutectic solidification phenomena. In the case where the solidification slag on the second conveyor 3A ₂ is at risk of being rapidly cooled, by installing a burner 42 for heat insulation, the dissipation of the internal potential heat of solidification slag is prevented.

[0094] Although not shown, a first conveyor 3A ₁ instead of the combination of the second conveyor 3A _2, be employed a long Ichiki pan conveyor for slow cooling in the second half portion solidifying the molten slag in the first half Good. Each slag casting apparatus is selected to have a length and a speed at which the cast slag can be sent to the next crushing step immediately after the formation of the solidified slag and the partial eutectic solidification under slow cooling are completed.

[0095] The first conveyor 3A ₁ of the mold. 3a, FIG. 13
Is a mold trough 43, which comprises an outer trough 43A made of heat-resistant steel or heat-resistant cast steel provided with a lining 43a, and an inner trough 43B made of non-rusting steel. If the slag adheres to the lining 43a, it cannot be removed smoothly. Therefore, the inner trough 43B, which is easy to replace when damaged and has a smooth surface, is placed on the outer trough 43A.

The inner trough 43B is shown in FIG.
A continuous plate-shaped solidified slag 6p having a width of 500 mm to 700 mm is formed as shown in FIG. Since the mold trough 43 is moving and continuous, the molten slag whose flowability has been improved by the addition of MgO is removed from the inner trough 43B.
Spread like water on top, solidified slag 6p naturally 25m
m to 30 mm.

[0097] The first conveyor 3A ₁ of the mold trough 43 in FIG. 12 is advanced by pushing the wheels 43m which is guided in the outer rail 45a by the pawl 44a of the sprocket 44. The mold trough 43 is in close contact with the subsequent mold trough, and no gap is formed between the inner troughs 43B, 43B to which the molten slag 6 is supplied. Each mold trough 43 moves on the inner rail 45b by a wheel 43m attached to the side surface, and when reaching the end of the conveyor, the mold trough 43 is guided by the outer rail 45a and falls down. The solidified slag 6p is replaced on the second conveyor 3A ₂ (see FIG. 14) or dropped on the fork screen 53 shown in FIG.

[0098] (b) of FIG. 15 shows a second conveyor 3A ₂ to put instead was solidified slag 6p. (C) of FIG.
Indicates solidified slag 6p on the pan conveyor adopted as the second conveyor. Since the second conveyor that converts the solidified slag 6p into the cast slag 6s obtained by eutectic solidification has no slag, only the bare rollers 46 and the outer trough 43A are used.

[0099] When the slag tapping amount of 50 tons / day or less, it is preferable to employ a circle-shaped conveyor 3A ₃ as shown in FIG. 16. The mold 3a moved by the revolving circle table 47 is a tray capable of forming a plate-shaped cast slag of a desired size. When the tray made of rustless steel moves half a turn in the counterclockwise direction, as shown in FIG. 17, it falls down around the hinge 3 b by the air cylinder 48, and the casting slag 6 s is placed on the chute 49 or the fork-like screen 53 of FIG. 18. Will be paid out.

[0100] If it takes time to feed the many molten slag tray conveyor 3A ₃ will retain the casting slag long. As a result, when it is necessary to prevent the temperature of the cast slag to be dispensed from dropping too much, the same burner as in FIG. 14 may be provided in the latter half of the movement. The empty tray is moved in the same direction and returned to the slag port of the reduction melting furnace 2A or the forehearth 36. FIG.
Reference numeral 3c in 6 denotes an electric motor and a speed reducer for rotating the circle table 47.

[0102] In such a conveyor 3A _3, it is also possible to solidify the molten pig iron which is once discharged per day. The ladle 5C that has received the molten pig iron from the tap hole 5a is carried to the position of the virtual line. The cast iron formed during the movement of the bread on the half circumference is discharged to the pit 50. When manufacturing a roadbed material that does not need to be eutectic solidified from the molten slag, the solidified slag may be discharged to the pit 50 at the time when the slag has rotated 1/4 from the forehearth 36. As can be seen from the above, the operation of the processing and transportation of the discharge from the reduction melting furnace is flexible in the circular conveyor.

As shown in FIG. 18, the slag casting apparatus 3A
The crushing device 3B installed on the paying-out side crushes the high-temperature casting slag 6s into 4 mm to 40 mm, preferably 5 mm to 25 mm. In this example and a spider crusher 3B ₁ and fine砕用rotary crusher 3B ₂ crude砕用.

[0103] Spider crusher 3B ₁ is provided with a large number of rotary wheel 3m which is attached to the coaxial. The casting slag 6s on the fork-like screen 53 is formed by a crushing bit of a rotary wheel 3m and a casting slag piece 6t.
Crushed. Since the cast slag 6s is not completely recrystallized and is relatively brittle, the cast slag is crushed quickly and with little power.

[0104] Rotary crusher 3B ₂ is provided with a pair of rolls 3n, 3n having a small uneven surface. By adjusting the distance between the roll axes, the cast slag pieces 6t are efficiently sized to the desired cast slag grains 6u of 5 mm to 25 mm. Therefore, it is not necessary to crush the slag to the size of natural gravel after the heat treatment described below.

[0105] In the lower rotary crusher 3B _2, 5
A sieving apparatus 3C for removing slag having a diameter of not more than mm is installed. The cast slag particles 6u of 5 mm or more that cannot pass through the vibrating hot screen are stored in the silo 54 until they are charged into any of the rotary heat treatment furnaces 4A of the heat treatment equipment, and if necessary, are kept warm using heat treatment exhaust gas or the like. You. 5
mm or less is supplied from the hopper 55 to the raw material supply device 2B.
And melted again in the reduction melting furnace.

[0106] in the lower rotary crusher 3B _2, the chute 61 of the swing equation inclined downward is installed. From this chute, high-temperature cast slag grains 6u are fed into rotary heat treatment furnace 4A. For example, two rotary heat treatment furnaces are provided to reduce the standby time of the cast slag particles 6u in the silo 54. The cast slag particles 6u are heated at 850 ° C. to 1,2 hours in the rotary heat treatment furnace 4A for 2 hours to 3 hours.
It is exposed to an atmosphere of 00 ° C.

This rotary heat treatment furnace 4A has a lining 4a
Burner 4b which is a drum having a diameter of 2 m to 3 m, and which applies a flame to the surface layer of the cast slag particles 6u to be deposited.
It has. The drum supported by the tires 4t, 4t is driven at 3 rpm via a gear 4g and a ring gear 4r.
Rotate at m to 4 rpm. The rolling of the cast slag particles 6u is promoted, and the temperature is maintained by contact with the heated lining 4a. The cast slag grains 6u are uniformly heated, and at the same time, the sharp corners of the cast slag grains formed during the crushing are softened and rounded.

While the cast slag grains 6u stay in the rotary heat treatment furnace 4A, the amorphous portion remaining in the cast slag grains is recrystallized. Cast slag particles 6u are made of CaO-SiO.
And a composition similar as possible to the eutectic point in the four-component phase equilibrium ₂ -Al ₂ O ₃ -MgO. Furthermore, the size of the cast slag grains is already 5 mm to 25 mm, which is easily heat-treated. Therefore, the eutectic solidification phenomenon occurs at a relatively low temperature, and a dense artificial gravel having a structure similar to natural gravel is generated. In this heat treatment, the residual internal strain of the cast slag grains 6u is also removed, so that the slag containing almost no FeO has extremely high toughness.

[0109] Incidentally, the exhaust gas of the rotary heat treatment furnace. 4A, with EK rotary kiln 1D ₁ of the exhaust gas, the rotary dryer 1A ₁ for drying the raw material, 1A _2, 1A
₃ (see FIGS. 3 and 4). When the drum is stopped so that the side cover 4c of the rotary heat treatment furnace 4A is at the bottom, the slag is discharged to the pit 62. Since slag powder is slightly generated during rolling in the furnace, slag powder of 5 mm or less is separated from the discharged slag by the sieve 4B. This slag powder is supplied from the hopper 63 to the raw material supply device 2.
Returned to B.

The artificial gravel 64 selected by the sieve 4B is 80
Since it has heat of 0 ° C. or more, it is put into a shaft-type heat recovery device 4C. Fresh air 6 introduced into heat recovery unit 4C
5 is heat exchange becomes 500 ° C. or higher, is used as an air burner of the rotary heat treatment furnace 4A and EK rotary kiln 1D ₁ (see FIGS. 3 and 4).

According to such an apparatus, by the following procedure, reduction melting of incineration ash and fly ash and the occurrence of a eutectic solidification phenomenon allow amorphous parts, heavy metals, harmful substances and gases to be removed as much as possible. A dense artificial gravel with no tissue can be produced.

Referring to FIG. 1, FIG. 3 and FIG. 4, incinerated ash and fly ash generated by incinerating household waste, sewage sludge, industrial waste, and the like are accumulated in first hopper 11 and second hopper 12. Keep it.

[0113] [First Step] incineration ash dryer 1A ₁ is turned, the fly ash is introduced into the dryer 1A _2. These raw materials are dried in the exhaust gas of the EK rotary kiln 1D ₁ and the rotary heat treatment furnace 4A. The water for fire extinguishing and the water for preventing dust from fly ash contained in the incineration ash evaporate, and the low-temperature volatile components in the incineration ash are incinerated. Exhaust gas with an odor generated by heating the incineration ash and fly ash is introduced into the deodorizer 1E, and the odor component is decomposed in an atmosphere of 650 ° C to 800 ° C. The ash mass is removed by the sieving devices 1B ₁ and 1B ₂ ,
Dry incineration ash and fly ash are stored in silos 14,15.

[Second Step] Dried incineration ash and fly ash,
The lightly burnt dolomite stored in the silo 16 and the ash stored in the silo 18 are weighed by the weighing device 1C and sent out by the conveyor 19. Further, although not shown in FIG. 3, when the sewage sludge dry powder or the like is also melted, it is weighed and sent. At this time, the raw materials are blended to a required mixing ratio such that MgO in the molten slag generated from these raw materials has a target content in the range of 5% to 20% or a content very similar thereto.

[Third Step] The prepared raw material is mixed with pulverized coal and plastic waste material at an intermediate position of the furnace body.
Charged to the K rotary kiln 1D _1. The raw material is heated by the combustion of the pulverized coal, and finally heated by the burner flame. Volatile components in plastic waste and raw materials are incinerated. The feed is secondarily dried and degassed, and part of the feed is reduced by pulverized coal. At the same time, coke breeze is produced from pulverized coal. When dolomite, lime, or the like is added to the raw material as an MgO-containing substance, lightly burned dolomite is also generated in the kiln. The raw material pretreated in this manner becomes a coarse sand and is stored in the container 26.

[0116] In the EK rotary kiln 1D _1, the temperature control of the combustion zone of the combustion zone and burner of the pulverized coal is extremely easy. 700 ° C to 1,000 ° C
C., and the incineration ash can be heated uniformly.
Even if fly ash is mixed with incinerated ash, the low-melting substances in the fly ash are incinerated and dioxin is decomposed.

[Fourth Step] The secondary dried raw material is charged into the reduction melting furnace 2A. Since the moisture and volatile components in the raw material have already been removed and the raw material has been preheated, the supply of heating energy in the reduction melting furnace 2A is reduced. Since in the feed is coke produced in the EK rotary kiln 1D ₁ are mixed, there is no need to add a reducing agent, except in special cases.

The melting of the raw material whose conductivity is improved by the coke breeze mixed is promoted, the Fe-based oxide in the raw material is reduced, and molten pig iron 5 is generated. Elements generated by reducing other heavy metals and reducible oxides in the raw material are dissolved in the molten pig iron 5. At the same time, a molten slag 6 having an extremely low gas content and containing as little as possible heavy metals or the like is generated and stays on the molten pig iron 5. Although the amount of FeO in the molten slag is extremely small, the MgO in the slag-making material prevents a decrease in the fluidity of the slag.

In order to maintain the submerged arc state even when the raw material is reduced and melted, the raw material is additionally charged one after another around the movable electrode 8 through the furnace lid 2b (see FIG. 8). Molten pig iron 5 stored in the hearth is intentionally left out of taphole 5a to ladle 5C (see FIG. 16) every one or two days, leaving a small amount.

The raw material charged into the reduction melting furnace 2A contains almost no volatile matter or moisture, so that a large amount of steam is not generated at the time of reduction melting, and a large amount of combustion gas is generated due to the burning of volatile substances. Absent. Since the low-boiling chlorides in the fly ash do not agglomerate in the low temperature region, no shell-like layer is formed in the raw material layer. Therefore, quiet reduction melting is realized, and the powdery and granular material is 650 ° C to 850 ° C.
Since it is preheated and has good fluidity, it is possible to realize unmanned and automatic operation of the furnace operation which has been said to be impossible until now. Further, the capacity of the furnace body can be increased.

[Fifth Step] The molten slag 6 discharged independently of the molten pig iron 5 is poured into a mold of the slag casting apparatus 3A to be formed into a plate having a substantially uniform thickness of about 25 mm. While conveying the mold, the surface layer of the molten slag is solidified. Using the recuperation from the molten portion of the solidifying the slag, CaO-SiO ₂ -
A eutectic solidified slag is cast at the eutectic point of Al ₂ O ₃ —MgO in the quaternary phase equilibrium state or as close as possible to it.

For example, in the molten slag 6, CaO is 5% to 36%, SiO ₂ is 38% to 55%, Al ₂ O
_{When 3} is 10% to 25% and MgO is 5% to 20%, the eutectic point of the molten slag is often 1,320 ° C. or less. The molten slag at a temperature of 1,500 ° C. or higher is cooled down to a temperature of 1,320 ° C. or lower in a liquid state in a mold, but when the temperature reaches the eutectic point, precipitation starts all at once. And
The temperature is maintained on its own until the entire composition is recrystallized based on the "phase law". However, complete recrystallization is not always achieved in the slag casting device 3A.

[Sixth Step] The cast slag 6s that has been subjected to the primary recrystallization is demolded, crushed by a crusher 3B, and sized. Since a lot of amorphous parts remain in the slag,
It can be crushed to 5 to 25 mm with relatively small force. Many of the cast slag grains 6u have sharp corners, but need not be crushed after the heat treatment. Note that the amount of fine powder generated during crushing is small.

[Seventh Step] The cast slag particles 6u charged into the rotary heat treatment furnace 4A are burned in a furnace by a burner.
It is exposed to an atmosphere at 0 ° C. to 1,200 ° C. The cast slag particles are uniformly heated by contact with the burner flame and contact with the heating lining due to rotation of the furnace body. 2
The cast slag particles staying for 3 hours or 3 hours are rolled by the repeated rise and fall of the inner wall based on the rotation of the furnace body, and become round. Recrystallization at the eutectic point in the quaternary phase equilibrium state is promoted, the cast slag grains do not leave an amorphous portion, and residual internal strain is also removed.

The produced artificial gravel 64 is pure, free of heavy metals and harmful substances, and has a very low gas content. A dense artificial aggregate having a structure similar to natural gravel can be obtained. Since there is also a temperature holding action by "phase law", the consumption of heat energy supplied until recrystallization is greatly reduced.

As can be seen from the above description, CaO—S
The limited range of the eutectic point of the ternary system of iO ₂ —Al ₂ O ₃ is expanded by modifying the quaternary system to which MgO is added, and the eutectic solidification is possible in the quaternary phase equilibrium state. Molten slag can be produced. By adding MgO, the fluidity of the molten slag is also improved, and it is possible to contribute to lowering of the slag melting point without adding CaO excessively. Therefore, handling in the subsequent process for producing artificial gravel from the molten slag becomes easy. The generated artificial gravel has long-term chemical and physical stability and mechanical strength without digestibility.

Next, an apparatus for producing artificial sand very close to river sand from molten slag which is detoxified and capable of eutectic solidification will be described with reference to FIG. This apparatus also employs the pre-processing equipment 1 shown in FIG. 3, but is not shown in FIG. FIG. 8 shows the reduction melting furnace 2A.
11 and the rotary heat treatment furnace 4A is the same as the furnace described with reference to FIG. The slag solidification equipment provided between the reduction melting furnace 2A and the rotary heat treatment furnace 4A is different from that shown in FIGS.

Referring to FIGS. 5 and 19, an air-mill type solidifying device 3S is employed as a slag solidifying facility. The coagulation device consists of molten slag splashing device 3S ₁ and sandy slag generating apparatus 3S _2. The molten slag scattering device has a slag receiving gutter 71 for receiving the molten slag 6 discharged from the reduction melting furnace 2A, and an air ejector 72 for blowing the molten slag flowing out of the slag receiving gutter with compressed air.

Slag receiving gutter 71 with lining
, Within a short time to suppress the heat radiation of the molten slag 6,
Supplying molten slag sand-like slag generating apparatus 3S ₂ to entry side opening. The air ejector 72 includes a pipe 72a that ejects compressed air upward from a lower portion of the slag receiving gutter 71,
It consists of an air compressor not shown. The air ejection pressure of the pipe is set high enough to cause the molten slag 6 to violently collide with the inner surface of the rotating drum described below.

[0130] sandy slag generating apparatus 3S ₂ consists horizontal type rotary drum 73 and the drum cooler 74.. The rotary drum 73 is an open-ended iron drum without lining, and is rotatably supported by rollers 73r, 73r. The drum rotated by a driving device (not shown) is inclined downward with respect to the moving direction of the slag. The drum cooler 74 constantly sprays cooling water to the outer surface of the drum to cool the rotating drum 73. The cooling water is blocked by the draining fins 73 a standing on the outer surface of the drum, and does not enter the rotating drum 73.

For example, the molten slag 6 blown from one end opening of the rotary drum 73 rotating at about 30 rpm hits the inner wall of the water-cooled drum with the blast air. The molten slag is thinned by the scattering force of the blast air and the impact force of the collision with the inner wall of the drum, and the surface is solidified by the cooling action of the water-cooled steel shell. The generated sandy slag 6w moves toward the other opening in the drum without adhering to each other. As the inner wall of the sand-like slag rises and falls repeatedly due to the rotation of the drum 73, the sand-like slag rolls to form a rounded outer shell.

The sandy slag 6w is gradually cooled until it is discharged from the rotating drum 73. Since sufficient length to the rotary drum 73 to suppress the dissipation of the internal potential heat of the slag is ensured, during the slow cooling, slag, CaO-SiO ₂ -
Partial primary recrystallization based on eutectic solidification phenomena in quaternary phase equilibrium Al ₂ O ₃ -MgO is promoted. Note that the cooling water sprayed on the drum 73 partially evaporates while flowing around the drum, and the remainder is dropped into the water reservoir 3w.

The sandy slag 6w is discharged onto the chute 75 and immediately charged into the rotary heat treatment furnace 4A. The artificial sand 76 completely recrystallized in the rotary heat treatment furnace becomes a chemically and physically stable artificial aggregate for concrete having a dense structure very close to river sand, which does not contain metals and harmful substances.

In the above description, an artificial aggregate is produced by reducing and melting a raw material obtained by adding fly ash to incinerated ash. Of course, only incineration ash, only sewage sludge dry powder, a mixture of incineration ash and sewage sludge dry powder, or a mixture of incineration ash, fly ash and sewage sludge dry powder can be used as a raw material. In any case, the composition of the raw materials to be charged into the reduction melting furnace is known in advance, and MgO is suitable for eutectic solidification.
May be added.

[0135]

EXAMPLES The present invention is, SiO _2, CaO, when generating molten slag mainly comprising Al ₂ O _3, highly target content or to those in the range from of 20% MgO in the molten slag is not 5% In order to obtain an approximate content rate,
That is, a slag-making material containing MgO is added to the raw material.
Thereby, CaO—SiO ₂ —Al ₂ O ₃ —MgO
Thus, a molten slag having a composition capable of eutectic solidification at the eutectic point in the quaternary phase equilibrium state or as close as possible to the eutectic point can be obtained. Therefore, some examples are given below.

FIG. 20 is a graph showing CaO—SiO ₂ —Al ₂ O ₃
A phase relationship at the liquidus temperature of the 15% Al ₂ O ₃ surface of -MgO system. The number on the side 81 indicates the content of CaO, the number on the side 82 indicates the content of SiO ₂ , and the side 83 indicates the content of MgO. The solid line and the thick broken line in the figure represent the boundary of the rocky material, and the numbers on the thin broken line indicate the solidification temperature.

Point A is a eutectic point, and points A ₁ and a
_{The portion up to 2} and a ₃ (see FIG. 21 in which the main part of FIG. 20 is enlarged) is a eutectic line in a region where recrystallization is likely to be induced during solidification. Note that FIG. 22, FIG. 24, FIG. 26, and FIG. F. Osborne, R.A. C. Debreeze, K.M. H. Ghee, H. M. Kurana co "CaO-MgO-Al ₂ O ₃ optimal composition of blast furnace slag inferred from -SiO ₂ quaternary liquid-phase data" AI
It is a quaternary phase equilibrium diagram described in ME Bulletin Vol. 200, pp. 33-45.

In order to recrystallize the solidified slag,
It is essential that the eutectic solidification temperature be 1,300 ° C. or less and that the movement of crystal molecules based on the high fluidity of the molten slag is easy. For this purpose, it is important that SiO ₂ is about 55% or less, and that forsterite crystals that easily cause an alkali-aggregate reaction when used as an artificial aggregate are not generated. Therefore, the lines Aa ₁ , Aa ₂ , and Aa ₁ shown in FIG. 21 which are near the ternary eutectic point of anorthite, pyroxine and melilite
It is necessary to adjust the blending of the slag-making material containing MgO so that the composition on Aa ₃ is obtained.

Some black points including the points A, a ₁ , a ₂ , and a ₃ and the other points B are eutectic points having a minimum solidification temperature of 1,300 ° C. or lower, or extremely eutectic points. It is an approximate point, and the respective compositions are as shown in Table 1. The columns of MgO at points A and B in the table are the target content rates described above, and the points a ₁ , a ₂ , a ₃ , b ₁ , b ₂
Etc. correspond to a content that is very close to the target content.

[Table 1]

FIG. 22 shows the case of 10% Al ₂ O ₃ , which is summarized in Table 2 in the same manner. Each point is a eutectic point in the quaternary phase equilibrium state or a point very similar thereto, and the solidification temperature, that is, the minimum temperature of the melting point is 1,300 ° C. or less. FIG. 23 is an enlarged view of the vicinity of the point in FIG.

[Table 2]

Similarly, the case of 20% Al ₂ O ₃ is shown in FIG.
And in FIG. Table 3 summarizes this. Each point is a eutectic point in a quaternary phase equilibrium state or a point very similar thereto, and the solidification temperature is 1,300 ° C. or less. The point g _{2 is} also a point very similar to the eutectic point in the quaternary phase equilibrium state, but the solidification temperature in this case is from 1,330 ° C. to 1,350 ° C.

[Table 3]

Similarly, the case of 25% Al ₂ O ₃ is shown in FIG.
Is represented in Table 4 summarizes this.
Each point is a eutectic point in the quaternary phase equilibrium state or a point very similar thereto, and the solidification temperature is 1,400
It is below ° C.

[Table 4]

To summarize the above, if CaO is 16% to 35%, SiO ₂ is 36% to 54%, Al ₂ O ₃ is 10% to 25%, and MgO is 5% to 20%, a quaternary system is obtained. It can be seen that a molten slag having a composition capable of eutectic solidification in a state as close as possible to the eutectic point in the phase equilibrium state is obtained. It is well known that the melting point of the molten slag increases when the content of Al ₂ O ₃ is too small or too large. When the content is less than 5% or more than 30%, the minimum temperature of the solidification point is about 1%. , 400 ° C. or higher. In such a case, it is necessary to increase the melting temperature of the incinerated ash, and this should be avoided because the consumption of heat energy increases.

In FIGS. 20 to 26, there are other eutectic points in the quaternary phase equilibrium state or points very similar thereto. In the case of 15% Al ₂ O _{3 in} FIGS. 20 and 21, the eutectic point C and the point c
_1, c ₁₁ a can be mentioned pick as shown in Table 5, the solidification temperature is 1,300 ° C. or less.

[Table 5] Similarly, in the case of 20% Al ₂ O _{3 in} FIGS. 24 and 25, the eutectic point H can be picked up as shown in Table 6, and the solidification temperature is 1,300 ° C. or less.

[Table 6] Similarly, in the case of 25% Al ₂ O ₃ in FIG. 26, the eutectic point K can be picked up as shown in Table 7, and its solidification temperature is lower than 1,400 ° C.

[Table 7] However, the viscosity of the molten slag also becomes high due to the high content of SiO ₂ , and the operation of flowing out the molten slag from the reduction melting furnace is inconvenient. Therefore, it should be noted that even though the eutectic point in the quaternary phase equilibrium state or a point very similar thereto is present, an unfavorable eutectic point exists.

The composition of the incinerated ash is not fixed,
For example, the composition is as shown in Table 8. Examples 1 and 2 are published slag composition data obtained by prior art electromelting and the like. Example 3 is the composition of the incinerated ash that was subjected to our tests.

[Table 8] When the above-mentioned incinerated ash is melted and turned into slag, the composition becomes as shown in Table 9. It should be noted that components in Examples 1 and 2 seem to be slightly adjusted, and the published values are listed as they are.

[Table 9] When the main composition of the slag is CaO, SiO ₂ , Al ₂ O ₃ , and MgO by melting and reducing the slag again, the composition of the slag is rewritten as shown in Table 10.

[Table 10] If the content of Al ₂ O _{3 in} Example 1 is assumed to be 20%, it will be point S in FIG. 24, and if the content of Al ₂ O _{3 in} Example 2 is assumed to be 25%, it will be point T in FIG. Assuming that the content of Al ₂ O _{3 in} Example 3 is 25%, a point U in FIG. 26 is obtained. Point S deviates significantly from eutectic points F and G, and points T and U deviate significantly from eutectic point J. Both solidify to anorthite and have a high slag solidification temperature.

The fly ash was mixed with the incinerated ash of the above Example 3 to obtain MgO.
The case where lightly-burned dolomite is added so that the content of becomes the eutectic point in the phase diagram will be described. First, the components of incinerated ash, fly ash and lightly burned dolomite are as shown in Table 11.

[Table 11] Incidentally, the particle sizes of the incinerated ash (A), fly ash (B) and lightly burned dolomite (C) are as shown in Table 12.

[Table 12]

In garbage incineration, incineration ash and fly ash are about 3:
Since light emission is generated in step 1, 7.9% of lightly burnt dolomite is added to a mixture of incineration ash / fly ash = 70/30. When this material is reduced and melted, the slag has a composition as shown in Table 13.

[Table 13] When the Al ₂ O ₃ content of the molten slag regarded as 20%, Fig. U next point in the 24, f ₃ points approximate to a eutectic point F
Matches.

Next, the case where incinerated ash and fly ash having different component compositions are used as raw materials will be described. The components of the incinerated ash (K) and fly ash (L) are shown in Table 14 together with the theoretical value of the dolomite (M) and that of the calcined dolomite (N).

[Table 14]

The components of the molten slag obtained by adding 4.0% of calcined dolomite to a mixture of incinerated ash / fly ash = 70/30 are shown in the column of Example 11 in Table 15, and incinerated ash / fly ash = 80/20. Example 1 when 5.5% of calcined dolomite was added to the mixture
The column of Example 13 shows the case where 5.4% of dolomite was added to the mixture of incineration ash / fly ash = 70/30 in the column of incineration ash / fly ash.
The case where 7.5% of dolomite was added to the mixture of fly ash = 80/20 is listed in the column of Example 14. In either case, substantially equal to the eutectic approximate point f ₃ in FIG. 24.

[Table 15]

Table 16 shows that the content of MgO in the molten slag was adjusted to 9%, 10%, and 15% by adding calcined dolomite to a mixture of incinerated ash / fly ash = 70/30. The mixing ratio of the raw materials and the component composition of the molten slag are shown.

[Table 16]

In case 1, if Al ₂ O ₃ is assumed to be 20%, the composition is far away from the eutectic point F in FIG. In case 2, if Al ₂ O ₃ is regarded as 20%,
Its composition is close to the point f ₃ in FIG. 24. This is as described in Example 11 of Table 15. In case 3, assuming that Al ₂ O ₃ is 15%, the composition is as shown in FIG.
It is far away from the eutectic points A and B in the middle. Therefore, Table 1
The incinerated ash and fly ash having the composition shown in FIG.
/ 30, 4.0% calcined dolomite
It turns out that it has to be added. Conversely, when the added amount of calcined dolomite is 0% or 22.35%, eutectic solidification in a state as close as possible to the eutectic point in the multiphase equilibrium state becomes impossible.

Table 17 shows that the content of MgO in the molten slag was adjusted to 8%, 10% and 15% by adding calcined dolomite to a mixture of incinerated ash / fly ash = 80/20. The mixing ratio of the raw materials and the component composition of the molten slag are shown.

[Table 17]

In case 4, assuming that Al ₂ O ₃ is 25%, the composition is far from the eutectic point J in FIG. In case 5, assuming that Al ₂ O ₃ is 20%, its composition is close to point f ₃ in FIG. This is the same as Example 12 in Table 15.
As described above. In case 6, Al
Assuming that ₂ O ₃ is 15%, the composition is far away from the eutectic points A and B in FIG. Therefore, when the incinerated ash and fly ash having the compositions shown in Table 14 are used at an incinerated ash / fly ash of 80/20, it is understood that 5.53% of calcined dolomite must be added. When the amount of the calcined dolomite is 0% or 24.92%, the solidification temperature of the slag increases, and a large amount of heating energy is required. In addition, the cooling proceeds rapidly after the slag is removed, and the slag becomes insufficiently recrystallized while leaving a large amount of amorphous.

In FIG. 20, MgO is about 6%.
% To about 14%, and in FIG.
0%. In FIG. 24, about 6% to about 17%, and in FIG. 26, about 3% to about 8%
It turns out that it is. For reference, FIG. 27 shows Al ₂ O ₃
Shows a phase relationship when the ratio is 30%. The slag has a very high melting point and a high viscosity when it contains a large amount of Al ₂ O ₃ , which is unsuitable for producing an artificial aggregate.

If Al ₂ O ₃ is kept in the range of about 10% to about 25%, 3% to 20% of MgO can eutectic solidify the molten slag. 20 to 26 described above are merely examples. 5% MgO
Below this, there is little room for adding MgO, and the range of component adjustment becomes narrow. Considering the range in which the component adjustment is easy, it can be seen that the target content of MgO in the molten slag may be any% in the range of 5% to 20%.

[Brief description of the drawings]

FIG. 1 is an overall procedure diagram of a method for producing an artificial aggregate for concrete from incinerated ash according to the first invention.

FIG. 2 is a procedure diagram of the latter half of the method for producing an artificial aggregate for concrete according to the second invention.

FIG. 3 is a system diagram of a first half of an apparatus for producing an artificial aggregate for concrete from incinerated ash according to a fourth invention.

FIG. 4 is a system diagram of a latter half of a manufacturing apparatus according to a fourth invention.

FIG. 5 is a system diagram of a latter half of an apparatus for manufacturing an artificial aggregate for concrete according to a fifth invention.

FIG. 6 is a longitudinal sectional view of an EK type rotary kiln.

FIG. 7 is a sectional view taken along line VII-VII of FIG. 6;

FIG. 8 is a sectional view of a submerged arc DC resistance furnace.

9A is a front view of a positive electrode, and FIG. 9B is a perspective view of the positive electrode.

FIG. 10A is a plan view of a positive electrode arranged on a furnace bottom, and FIG. 10B is a connection diagram of a power supply and a flexible conductor.

FIG. 11 is a sectional view of a submerged arc DC resistance furnace having a forehearth.

FIG. 12 is a front view of a first conveyor of the slag casting apparatus.

FIG. 13 is a perspective view of a mold arranged on a first conveyor.

FIG. 14 is a front view of a second conveyor of the slag casting apparatus.

15A is a cross-sectional view of a first conveyor, FIG. 15B is a cross-sectional view of a second conveyor, and FIG. 15C is a cross-sectional view of a mold including only an outer trough on which solidified slag is placed.

FIG. 16 is a plan view of a slag casting apparatus employing a circular conveyor.

FIG. 17 is a sectional view taken along line XVII-XVII in FIG. 16;

FIG. 18 is a layout diagram of each device after the slag solidification facility in the artificial gravel production device.

FIG. 19 is a layout view of main devices in an artificial sand production device.

FIG. 20 is a phase relationship diagram of a CaO—SiO ₂ —Al ₂ O ₃ —MgO-based 15% Al ₂ O ₃ surface at a liquidus temperature.

FIG. 21 is an enlarged view of a main part of FIG. 20;

FIG. 22 is a phase relationship diagram of a 10% Al ₂ O ₃ surface of a CaO—SiO ₂ —Al ₂ O ₃ —MgO system at a liquidus temperature.

FIG. 23 is an enlarged view of a main part of FIG. 22;

FIG. 24 is a phase relation diagram at the liquidus temperature of the 20% Al ₂ O ₃ surface of the CaO—SiO ₂ —Al ₂ O ₃ —MgO system.

FIG. 25 is an enlarged view of a main part of FIG. 24;

FIG. 26 is a phase relationship diagram of a 25% Al ₂ O ₃ surface of a CaO—SiO ₂ —Al ₂ O ₃ —MgO system at a liquidus temperature.

FIG. 27 is a phase relationship diagram at a liquidus temperature of a 30% Al ₂ O ₃ surface of a CaO—SiO ₂ —Al ₂ O ₃ —MgO system.

[Explanation of symbols]

1A ... drying apparatus, 1C ... weighing device, 1D ₁ ... EK rotary kiln, 2A ... reduction melting furnace, 3A ... slag casting apparatus, 3B ... crushing device, 3S ... wind砕式coagulator, 3a ... mold, 4A ... Rotary heat treatment furnace, 5: molten pig iron, 6: molten slag, 6s: cast slag, 6u: cast slag particles, 6w ...
Sandy slag, 7: raw material, 23: pulverized coal, 24: plastic waste material, 64: artificial gravel, 76: artificial sand.

Claims (5)

[Claims] 1. A method for producing an artificial aggregate from incinerated ash produced by incinerating household waste, sewage sludge, industrial waste, or the like, or molten slag of sewage sludge dry powder, The drying process of heating to 250 ° C. to 250 ° C. and the weighing of the dried incineration ash and fly ash and the slag-making material containing MgO make 5% to 20% of MgO in the molten slag produced from these raw materials. A mixing step of mixing the raw materials at a predetermined blending ratio so as to have a target content rate in the range of or very similar to the target content rate, and adding the pulverized coal and plastic waste material to the prepared raw materials to substantially the entire area of the furnace body From 700 ° C to 1.0
A heating step of preheating and degassing the raw material and partially reducing the raw material at the same time as generating coke breeze from the pulverized coal while maintaining the temperature at 00 ° C .; and a Fe-based oxide in the preheated raw material. Molten iron to form molten pig iron, dissolve other heavy metals and the elements generated by reducing reducible oxides in this molten pig iron, and have the extremely low gas content to allow the above heavy metals, etc. A reduction melting step of generating molten slag that is not included in the molten pig iron and staying in the upper part of the molten pig iron, and flowing the molten slag that has been slagged independently of the molten pig iron into a mold into a plate shape and transporting the molten slag. A casting step of forming a casting slag during the conveyance, a crushing step of releasing the casting slag from the mold, and crushing the slag to 4 mm to 40 mm, preferably 5 mm to 25 mm; 850 ° C to 1,2
Rolling in an atmosphere of 00 ° C. to recrystallize an amorphous portion remaining in the cast slag grains and to remove residual internal strain of the cast slag grains; A method for producing an artificial aggregate for concrete from incinerated ash, characterized by producing a recrystallized artificial gravel. 2. The drying step according to claim 1, wherein
Subsequent to the heating step and the reduction melting step, the molten slag discharged independently of the molten pig iron is caused to collide with a water cooling wall in an air stream, and sand slag is generated from the molten slag by contact with the water cooling wall. The sandy slag is rolled in an atmosphere at 850 ° C. to 1,200 ° C. to recrystallize the amorphous portion remaining in the sandy slag and to reduce the residual internal strain of the sandy slag. A method for producing an artificial aggregate for concrete from incinerated ash, comprising: a heat treatment step of removing; and producing artificial recrystallized sand having a dense structure. 3. An easy-to-reduce Fe contained in incinerated ash for producing artificial aggregate from incinerated ash generated by incineration of household waste, sewage sludge, industrial waste, and the like, and molten slag of sewage sludge dry powder. , Cr, P and the like are melt-reduced to produce molten pig iron, and a molten slag mainly composed of SiO ₂ or the like having a composition as low as possible and having eutectic solidification,
A method for producing a dense recrystallized artificial artificial aggregate having a very low gas content from concrete from the molten slag, comprising: a drying step of heating the incinerated ash or fly ash to 120 ° C. to 250 ° C .; By weighing the incinerated ash and fly ash and the slag-making material containing MgO, the content of MgO in the molten slag produced from these raw materials in the range of 5% to 20% or very close to the target content And mixing the raw materials with a predetermined mixing ratio so that the mixing ratio can be adjusted, and adding pulverized coal and waste plastic to the prepared raw materials to reduce substantially the entire area of the furnace body from 700 ° C. to 1,0 ° C.
A heating step of preheating and degassing the raw material and reducing a part of the raw material at the same time as generating coke breeze from the pulverized coal while maintaining the raw material to be reduced and melted. A method for producing artificial aggregate for concrete from incinerated ash, which is characterized by performing a pretreatment. 4. An apparatus for producing artificial aggregate from incinerated ash generated by incineration of household waste, sewage sludge, industrial waste, or the like, or molten slag of sewage sludge dry powder, 5% to 20% of MgO in the molten slag generated from these raw materials by mixing a drying device for drying at a temperature of 250 ° C. to 250 ° C., and a dried incineration ash and fly ash and a slag-making material containing MgO. A weighing device that adjusts the raw materials to the required mixing ratio so that the target content ratio in the range of or very close to the target content ratio, and the prepared raw materials are charged, and pulverized coal and plastic waste are added at the middle position of the furnace body In this manner, coke breeze is produced from the pulverized coal while substantially the entire area of the furnace body is maintained at 700 ° C. to 1,000 ° C., and at the same time, preheating, degassing, and EK type rotary kiln for reducing the part, and reducing and melting the preheated raw material to reduce Fe-based oxides in the raw material to produce molten pig iron, and other heavy metals and Reduction melting that dissolves the elements generated by reducing the reducible oxides, generates molten slag that has a very low gas content and contains as little as possible the heavy metals, etc., and stays at the top of the molten pig iron. A furnace, and a slag casting apparatus for flowing molten slag discharged independently of the molten pig iron into a mold into a plate shape and transporting the molten slag, and solidifying the slag during the transportation. Immediately after releasing from the mold, 4mm
And a crushing device for crushing the cast slag particles generated by the crushing at 850 ° C. to 1,2 mm.
A rotary heat treatment furnace that rolls in an atmosphere of 00 ° C. to recrystallize the amorphous portion remaining in the cast slag grains and remove residual internal strain of the cast slag grains. An apparatus for producing artificial aggregate for concrete from incinerated ash, characterized in that it produces recrystallized artificial gravel. 5. The drying device, the weighing device according to claim 4,
In addition to the EK type rotary kiln and the reduction melting furnace, the molten slag discharged independently of the molten pig iron is put in an air stream to collide with a water cooling wall, and the molten slag is brought into contact with the water cooling wall to form a sandy slag. And a blasting-type coagulation device for producing a slag, wherein the sandy slag is rolled in an atmosphere of 850 ° C. to 1,200 ° C. to recrystallize an amorphous portion remaining in the sandy slag and to form the sandy slag. An apparatus for producing artificial aggregate for concrete from incinerated ash, comprising: a rotary heat treatment furnace that removes residual internal strain of; and generating artificial sand having a fine structure and recrystallized.