JPH09310110A - Treatment of refuse incineration flying ash and production of molten iron - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a melting treatment of a refuse incineration fly ash and a producing method of molten iron. SOLUTION: A cylindrical furnace 1 provided with primary and secondary tuyeres, dust collector, etc., is used to obtain the molten iron, slag and heavy metal-containing molten fly ash with a continuous or a batch operation through the procedure of following (a)-(d) processes. (a) Flux-coke (KK) packing layer 6' is formed to a level including the primary tuyeres 3. (b) a mixture packing layer 7' of cinerated fly ash cement bond aggregate, scrap(SC) and ore is placed on the above packing layer and further, the flux KK pucking layer 6' is placed on this layer 7' and layers 6' and 7' are alternately formed in plural layers. (c) Combustion assist gas and fuel are blown from the primary tuyeres 3 and the combustion assist gas from the secondary tuyere 4 to burn the KK, fuel and CO gas. (d) While executing the melt of the flux, SC and the aggregate and the volatilization of the heavy metal in the incineration fly ash, smelting reduction of the ore is executed. At the same time of obtaining the molten iron 8A, the slag 8B as material for roadbed and the molten fly ash 17 as metallic raw material can be obtd. and resourcing of refuse incineration fly ash and the reduction of treating quantity due to landfill treatment can be achieved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method capable of converting incineration fly ash (dust ash of "dust") generated from a refuse incinerator into a useful resource and producing hot metal.

[0002]

2. Description of the Related Art At present, most of pig iron is produced by a blast furnace. The blast furnace pig iron method is extremely excellent as a mass production technology for pig iron, but with this method, there is a restriction of raw fuel that the iron source is limited to sinter and the fuel is limited to high quality coke. In addition, since blast furnaces have become huge in recent years and cannot be stopped and started easily, they lack flexibility in responding to changes in steel demand. On the other hand, at present, most of the scrap melting is carried out in an electric furnace, and the production cost of the hot metal in the electric furnace and the steel made from the same is considerably higher than that in the case of using the blast furnace ironmaking method.

In order to solve the above-mentioned problems, the present inventors and the present applicants proposed a pig iron manufacturing method and a manufacturing apparatus using a cylindrical furnace as a furnace and scrap as an iron source (Japanese Patent Laid-Open No. Hei 1). -290711, JP-A-3-150
309).

In these methods, a cylindrical furnace 1 of the converter type as schematically shown in FIG. 4 is used.

FIG. 4 is a vertical cross-sectional view for explaining a raw material charging state of a conventional cylindrical furnace. As shown in the figure, this cylindrical furnace 1 has an opening (furnace opening) 2 for discharging the gas generated in the furnace and charging the raw material in the upper part of the furnace, and a combustion-supporting gas and fuel as necessary in the lower part of the furnace wall. A primary tuyere 3 to be blown in, a secondary tuyere 4 to blow a combustion-supporting gas into the upper furnace wall thereof, and a tapping waste slag outlet 5 are provided at the bottom of the furnace.

In order to manufacture the hot metal 8A using the above-mentioned tubular furnace 1, first, a coke filling layer 6 containing a solvent medium is formed in the lower part of the furnace, and a scrap-iron ore filling layer 7 is formed thereon. The scrap-iron ore packed bed 7 is a packed bed of scrap and iron ore. Then, a combustion-supporting gas (oxygen or oxygen-containing gas) is blown into the lower coke-filled layer 6 from the primary tuyere 3 to cause a reaction of the following formula (1), and the reaction heat generates a high temperature of the coke-filled layer 6. And to generate CO gas.

[0007] The CO gas generated by the equation (1) causes a reaction (secondary combustion) of the following equation (2) with the combustion-supporting gas blown from the secondary tuyere 4 in the scrap-iron ore packed bed 7. The heat of reaction is used for heating and melting scrap and iron ore.

[0008] The molten iron ore (molten iron oxide) is dropped into the lower coke filling layer 6 and is reacted with the high temperature coke as shown in the following formula (3) to be reduced.

[0009] The CO generated by the formulas (1) and (3) reacts with oxygen in the combustion-supporting gas in the scrap-iron ore packed bed 7 and is secondarily burned, so that it is effectively used for heating and melting them. And high thermal efficiency is achieved. In this way, hot metal 8
A and slag 8B are manufactured.

On the other hand, recently, the amount of dust generated has been increasing year by year. The incineration fly ash generated from the refuse incinerator is about 3 of garbage.
The amount per weight% increases with the amount of generated dust, and has become a problem in recent years. This incineration fly ash is Pb,
Since it contains harmful substances such as heavy metals such as Cd and Zn and dioxins, it was designated as specially controlled municipal waste in April 1991 as having a risk of causing damage to human health. . Therefore, direct landfill cannot be done without intermediate treatment specified by the Minister of Health.

The following intermediate treatment methods for incineration fly ash are as follows (Journal of Japan Society of Waste Science: Appropriate treatment of soot and dust which is special general waste, Vol.
1, PP.18-31,1994).

[0012] Using a cement solidification facility, homogenize and knead with a sufficient amount of cement to make it a chemically stable state so that heavy metals do not elute, and adequately cure the properly granulated or molded product. Solidification method (cement solidification method).

A method (chemical treatment method) in which a chemical treatment facility is used to uniformly knead and knead a sufficient amount of chemicals to chemically stabilize the heavy metals so that they are not eluted.

A method in which a heavy metal is sufficiently eluted in an acid or other solvent and then dehydration treatment is performed, and the heavy metal in the eluate is chemically stabilized (extraction treatment method using an acid or another solvent).

A method (melting and solidifying method) of sufficiently melting and solidifying by using a melting facility and treating sludge or molten fly ash generated by melting by the above methods (1) to (3).

However, the chemical methods 1) to 3) have the following problems 1) to 3).

1) Since it is difficult to delicately control reaction conditions such as the rate of addition of chemicals, the treatment method is easily affected by the landfill standard value and the elution method.

2) Dioxins contained in the fly ash are accumulated as they are in the landfill.

3) Since it is basically landfilled, it does not contribute to the reduction or volume reduction of garbage.

On the other hand, in the above-mentioned melting and solidifying method, since it is carried out in a high temperature atmosphere, the volume of dust can be reduced, and heavy metals having a low boiling point are preferentially volatilized and separated and recovered as molten fly ash. Also, dioxins are decomposed by 99% or more,
The substances generated after melting are harmless.

Further, if the collected molten fly ash is regarded as a non-ferrous metal raw material, it is considered that the non-ferrous metal can be sufficiently recovered, and there is an advantage that it can be recycled as a resource. However, since refuse incineration fly ash has a very small particle size (15 to 70 μm, which is equivalent to wheat flour), it will scatter if it is charged from the top of the melting furnace.

[0022]

SUMMARY OF THE INVENTION According to the present invention, when producing hot metal, the refuse incineration fly ash is melt-processed in a high temperature atmosphere to convert most of it into slag and to adjust the slag basicity. It is used not only as a material for roadbed materials, but also for recovering the molten fly ash containing heavy metals in the refuse incineration fly ash from the exhaust gas generated during the melting process and reusing it as a metal raw material.

The object of the present invention is to eliminate the scattering loss by charging the refuse incineration fly ash as an agglomerate into the hot metal production furnace,
An object of the present invention is to provide a method for obtaining molten fly ash containing molten pig iron, slag, and heavy metal while efficiently melting and processing the refuse incineration fly ash.

[0024]

The gist of the present invention resides in the following melting treatment of refuse incineration fly ash and a method for producing hot metal.

Openings for gas discharge and raw material charging in the upper part of the furnace, a plurality of openings in the bottom of the furnace and / or a plurality of primary tuyeres in the lower furnace wall, and a plurality of single steps in the upper furnace wall Using a tubular furnace equipped with individual secondary tuyere, taphole at the bottom of the furnace, slag outlet at the bottom of the furnace wall or taphole at the bottom of the furnace and an exhaust gas dust collector, the following a. The hot metal and slag are manufactured by continuous or batch operation according to the procedure of
A method for melting waste incineration fly ash and a method for producing hot metal, which comprises recovering molten fly ash containing heavy metals from the exhaust gas.

A. A solvent-coke packed layer is formed from the furnace bottom to a level including the primary tuyere.

(B) A mixture of the above solvent / solvent-agglomerate of refuse incineration fly ash (hereinafter referred to as cement bond agglomerate) in which cement is bonded on the coke packed layer, iron source scrap and iron source ore. A plurality of layers of a solvent-coke filling layer are alternately formed on the filling layer and further on the mixed filling layer.

C. Combustion of coke, fuel and generated CO gas by blowing combustion-supporting gas and fuel from the primary tuyere and combustion-supporting gas from the secondary tuyere.

D. The iron source ore is melt-reduced while performing the solvent treatment, the iron source scrap and the cement bond agglomerate melting treatment and the volatilization treatment of the heavy metal in the refuse incineration fly ash.

The above "incineration fly ash" means the dust ash of "dust" generated when incinerating refuse.

The above-mentioned "iron source ore" is an ore such as iron ore, iron manganese ore, manganese ore and the like.

The above "heavy metal" refers to metals such as Pb, Zn and Cd, and "molten fly ash" containing these is usable as a raw material for the above metals.

The produced slag is adjusted in basicity and can be used as a material for roadbeds.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION First, an example of a process for producing a cement bond agglomerate of refuse incineration fly ash used in the method of the present invention will be described. This manufacturing process is as follows.

Raw material mixing / kneading process: Particle size 15 to 70 μm
Waste incineration fly ash, cement and water in weight ratio (1):
(0.08 to 0.10): Mix and knead to (0.024 to 0.035). The type and properties of the cement are not limited, but preferable cements are Portland cement, blast furnace cement, fly ash cement and silica cement.

Molding Step: FIG. 1 is a partially cutaway perspective view showing an example of a molding die used for producing a cement bond agglomerate. As shown in the figure, the molding die 10 is provided with a plurality of molding spaces 13 constituted by a molding frame 11 on the outer periphery and a partition frame 12 inside thereof. The plane dimension of this molding space 13 is about 20-
The 90 mm square and the height of the partition 12 are about 950 to 1000 mm. Both of the inner wall surfaces of the molding frame 11 and the partition frame 12 are provided with a draft angle as illustrated for die cutting.

The above-mentioned molding space 13 is filled with the mixed / kneaded product obtained in the above step, a pressure is applied, and this pressure is adjusted to mold so that the porosity becomes 22 to 25%. . For example, when molding to a thickness of 60 mm in a 60 mm square molding space 13, the above porosity can be obtained by setting the molding pressure to 20 to 30 kg / cm ² . With such a porosity, the melt processing reaction can be promoted to the inside while securing the strength of the cement bond agglomerate described below.

Curing process: After molding in the above process,
The atmosphere inside the mold 10 is adjusted to saturated steam at 70 ° C., and cured for 24 hours to cure.

Die-cutting and crushing step After the curing in the above steps, die-cutting is performed.

FIG. 2 is a perspective view showing the shape of the molded product obtained in the above process after die cutting.

After demolding, an integrated molding 14 is obtained as shown in the figure. This is crushed and separated by a jet chisel or the like to obtain a plurality of cement bond agglomerates 15.

This cement bond agglomerate 15 is
Since it is manufactured by such a process, a high temperature firing process such as the case of manufacturing a sintered ore can be omitted. Most of the refuse incineration fly ash is a fine powder with a particle size of 70 μm or less, but according to this method, the refuse incineration fly ash can be easily charged into the cylindrical furnace without scattering.

Next, referring to FIG. 3, a method of melting the cement bond agglomerates of the refuse incineration fly ash of the present invention and a method for producing hot metal and the like will be described.

FIG. 3 is a vertical cross-sectional view showing an example of the constitution of the apparatus used in the method of the present invention and the state of raw material filling. In the example shown in FIG. 3, the tubular furnace 1 has gas discharge and cement bond agglomerates, iron source scrap, iron source ore (iron ore, iron ore,
Iron manganese ore, manganese ore, etc.), an opening (furnace port) 2 for charging raw materials such as solvent and coke, a primary tuyere 3 on the lower furnace wall, and a secondary tuyere 4 on the upper furnace wall. At the bottom of the furnace, there is provided a tapping waste slag port 5, a skinmer 9 for separating the hot metal 8A and the slag 8B, and a dust collector 16 for collecting the molten fly ash 17 from the exhaust gas 18. The arrangement of the primary tuyere 3 is shown as a single stage and a plurality of examples are shown, but the primary tuyere 3 may be provided only on the furnace bottom or may be provided on both the furnace bottom and the lower furnace wall. The raw material charging means is conventional and is omitted.

As shown in FIG. 3, the solvent-coke packing layer 6'-1 is three layers, and the mixed packing layer 7'-1 made of iron source scrap, iron source ore and cement bond agglomerate is two layers. The charging and operation in some cases are described in a. ~ C. Perform in the process of.

A. First charging step: From the opening 2,
First, coke and a required solvent are charged and filled to form a solvent-coke filling layer 6'-1 from the furnace bottom to a level including the primary tuyere 3. A mixed and packed layer 7'-1 of the above three kinds of raw materials is formed on this layer, and then a solvent-coke packed layer 6'-2 and the mixed and packed layer 7'-2 are sequentially formed.
And a solvent-coke filling layer 6'-3 is formed.

B. Smelting reduction and volatilization and recovery process of heavy metals: Combustion-supporting gas and fuel as necessary from the primary tuyere 3,
A combustion-supporting gas is blown from each of the secondary tuyere 4 to reduce some iron-source ore and generate reduced iron or the like.
The reduced iron and the like, the iron source scrap, and most of the iron ore are melted and reduced in the solvent-coke packed bed 6'-1 to mainly produce hot metal 8A. At the same time, the solvent medium and the cement bond agglomerate are melted to mainly produce the slag 8B.

At this time, the heavy metals in the cement bond agglomerate are volatilized under a high temperature gas atmosphere (1300 to 1400 ° C.) between the primary tuyere 3 and the secondary tuyere 4, and are discharged into the exhaust gas 18. Move. The exhaust gas 18 is processed by the dust collector 16 to recover the molten fly ash 17 containing heavy metals.

C. Hot metal slag process: The generated hot metal 8A and slag 8B are discharged from the hot metal discharge port 5 to the outside of the furnace, and a skinmer 9 provided outside the furnace separates the hot metal 8A and the slag 8B.

In the case of continuous operation, the above b. And c. While continuing the process, the mixed packed bed 7'consumed in the reducing operation and the dissolving operation is formed. Then, a solvent-coke filling layer 6'is similarly formed.

Above a. And b. The purpose of carrying out the operation of (1) is as follows. First, the coke is partially oxidatively burned by the formula (1) with the combustion-supporting gas blown from the primary tuyere 3 in the lowermost solvent-coke packed layer 6'-1. Is generated as a main component to maintain the solvent-coke packed layer 6'-1 at a high temperature, and the iron source scrap formed on the upper part thereof,
Mixed packed bed 7'of iron source ore and cement bond agglomerate
-1 is mainly to partially reduce the iron ore by the following formula (4) or the like to generate reduced iron.

[0052] Secondly, the produced reduced iron and the combustion-supporting gas blown from the secondary tuyere 4 in the scrap packed bed cause the gas containing CO as a main component in the lower portion to be secondarily burned by the equation (2). By heating and melting the reduced iron and scrap by the heat generation of the secondary combustion, most of the iron ore is melted and reduced in the solvent-coke packed bed 6'-1 by the above formula (3) to melt the hot metal. 8A is generated, and at the same time, the cement bond agglomerate is melted to form slag, and the slag 8B is prepared by adjusting the slag basicity (CaO / SiO ₂ ) range to 1.15 to 1.25 by the solvent.

Thirdly, as described above, the heavy metals in the cement bond agglomerate are volatilized and transferred into the exhaust gas 18, and the fly ash 17 can be recovered by the dust collector 16.

The desired number of layers and the thickness of each packed layer at the time of the first charging / charging change depending on the shape and volume of the tubular furnace. Desirable conditions are one layer for the bottom solvent-coke filling layer 6'-1 with a thickness of 1200 to 1300 mm, one for the middle solvent-coke filling layer 6'-2, and a thickness of 350-
About 400 mm, solvent solvent on top-coke filling layer 6'-3
1 layer, thickness of 350-400 mm, mixed packing layer of iron source scrap, iron source ore and cement bond agglomerate 7'-
1,7'-2 has one layer each and each thickness is about 450-500 mm. The desirable range of the bulk density of the mixed packing layer 7'is 1.8 to 3.
It is about 0t / m ³ .

In the case of continuous operation, the amounts of iron source scrap, iron source ore and cement bond agglomerates that are sequentially charged and filled are the amounts to be heated and melted in the melting operation, and the amounts of coke are consumed in the reducing operation. The amount. Similarly, the amount of the solvent medium is an amount determined from the balance between the slag component value in the other raw materials to be charged and the target slag basicity.

When the solvent-coke filling layer 6'and the mixed filling layer 7'are formed, either batch charging after pre-mixing or mixed charging by individual dosing may be used. The former is preferably used from the viewpoint of improving the uniformity of the bulk density in the layer.

In carrying out the method of the present invention, the primary tuyere 3
Is arranged on the furnace bottom and / or the lower furnace wall, and the secondary tuyere 4 is arranged above it in one or more stages. Further, it is desirable that the number of primary tuyere 3 arranged in the horizontal direction is 4 to 6 and the range of the arrangement angle between the tuyere is 60 to 90 degrees. The number of secondary tuyeres 4 arranged in the horizontal direction is 6
~ 8 multiples, the range of placement angle between the tuyere
It is desirable to set it to 45-60 degrees. The position of the secondary tuyere 4 is set to the lower end of the packed bed of reduced iron, iron source scrap and cement bond agglomerate when the reducing operation is completed, and the secondary combustion heat is utilized for heating and melting these. This is because it is desirable in the above.

The combustion-supporting gas blown from the primary tuyere 3 and the secondary tuyere 4 contains oxygen or oxygen.
Furthermore, it is desirable to blow fuel (gas or liquid fuel such as pulverized coal, heavy oil, natural gas) together with the above-mentioned combustion-supporting gas from the primary tuyere 3. The reason is that the coke ratio must be increased as the iron source ore usage rate increases, and in this case, the space occupied by the coke increases. Therefore, in the case of a small-sized tubular furnace, there occurs a situation in which the space for charging the iron source scrap and the ore cannot be secured. However, the above charging space can be secured by using fuel to reduce the amount of coke used.

[0059]

【Example】

(Example of the present invention) A cylindrical furnace (diameter: 1.7 m;
Using a converter furnace with a height from the bottom to the mouth of the furnace of 3.9 m and an internal volume of 7.6 m ³ , a hot metal production operation test was conducted under the conditions shown in Table 1, Table 2, Table 3, and Table 4 and the following. It was Table 1 shows the composition of the iron ore used, Table 2 shows the composition of coke and pulverized coal, Table 3 shows the composition of refuse incineration fly ash, and Table 4 shows the composition of Portland cement used for agglomeration.

[0060]

[Table 1]

[0061]

[Table 2]

[0062]

[Table 3]

[0063]

[Table 4]

Production target Hot metal amount: 20 tons Iron source: Iron ore shown in Table 1; 75 Wt% in terms of iron content scrap; Maximum size 0.5 m Bulk density 3500 kg / m ³ Purity of iron 99 Wt% Iron content value 25 Wt% Waste incineration The weight ratio of fly ash to Portland cement to water is 1: 0.08: 0.024 Raw material charging and filling: 15 tons in total is divided into two as shown in Fig. 3 Bulk density of mixed packed bed: 3.0t / m ³ Primary tuyere: 4 pieces installed at 90 degree intervals on the furnace side wall 1.2m from the bottom of the furnace Secondary tuyere: 6 pieces installed at 60 degree intervals on the side wall of the furnace 2.2m from the bottom of the tap tap discharge: center of the bottom As a basic condition of operation, oxygen was used as a combustion-supporting gas blown from the primary tuyere, and the flow rate was 1500 Nm ³ / hr. At the same time, pulverized coal was blown at 800 kg / hr. Oxygen is used as the combustion-supporting gas blown from the secondary tuyere, the flow rate is 300 Nm ³ / hr
Then, the molten fly ash was recovered while producing the hot metal and the slag according to the above-mentioned process operation.

(Comparative Example) An operation test was conducted under the same conditions as in the present invention example except that the incineration fly ash was not used.

Table 5 shows the operation results in comparison.

[0067]

[Table 5]

As shown in Table 5, in the examples of the present invention, by using the cement bond agglomerate, the carbon and CaO contents in this agglomerate can be effectively utilized, and coke,
The amount of pulverized coal and solvent (limestone) used was reduced.

Regarding the obtained molten fly ash and slag,
Table 6 shows examples of amounts and compositions.

[0070]

[Table 6]

Judging from the content of heavy metals in the molten fly ash shown in Table 6, this molten fly ash can be regarded as a non-ferrous metal raw material. This means that the economical Pb and Zn content levels when mining Pb ore and Zn ore, respectively, are
It is set to 4.0 Wt% and 3.5 Wt%, and their contents in this molten fly ash are almost at the same level.

According to the slag elution test shown in Table 6, low
Heavy metals were not detected even by the pH method. Therefore, this slag can be used as a material for roadbeds from the viewpoint of other components.

Calculating from the amount of slag generated, about 84 Wt% of the incineration fly ash could be effectively used, and the amount of landfill disposal was greatly reduced.

[0074]

According to the method of the present invention, a tubular furnace which is much smaller and simpler than a blast furnace is used, and hot metal is produced by a highly flexible method. It is possible to obtain a slag whose basicity is adjusted and a heavy metal content is low, and a molten fly ash containing a heavy metal, by melting the refuse incineration fly ash, which is becoming a problem in securing. This slag can be used as a material for roadbeds, and molten fly ash containing heavy metals can be used as a metal raw material. As a result, the waste incineration fly ash is recycled and the amount of landfill is reduced.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing an example of a molding die for producing a cement bond agglomerate used in the method of the present invention.

FIG. 2 is a perspective view showing a shape of a molded article manufactured by the molding die of FIG. 1 after die cutting.

FIG. 3 is a vertical cross-sectional view showing an example of the configuration of a device used in the method of the present invention and the state of raw material filling.

FIG. 4 is a vertical sectional view for explaining a raw material charging state of a conventional cylindrical furnace.

[Explanation of symbols]

1: Cylindrical furnace, 2: Opening part (furnace mouth), 3: Primary tuyere, 4: Secondary tuyere, 5: Pig iron discharge slag opening, 6: Coke filling layer, 6 ': Solvent-coke filling Layer, 7: Scrap-iron ore packed layer, 7 ': Mixed packed layer consisting of scrap, ore and cement bond agglomerate, 8A: hot metal, 8B: slag, 9: skinmer, 10:
Mold, 11: Mold form, 12: Partition frame, 13: Mold space, 14: Molded product, 15: Cement bond agglomerate, 1
6: Dust collector, 17: Molten fly ash, 18: Exhaust gas

Claims (1)

[Claims] 1. An opening for discharging gas and charging raw materials in the upper part of the furnace, a plurality of openings in the bottom of the furnace and / or a plurality of primary tuyeres in the lower furnace wall, and a single step or a plurality of steps in the upper furnace wall. Using a tubular furnace equipped with multiple secondary tuyeres, tapholes at the bottom of the furnace, slag outlets at the bottom of the furnace wall or tapholes at the bottom, and a dust collector for exhaust gas Medium solvent to the level including the primary tuyere-
A coke packed bed is formed, and a solvent medium at the bottom of the furnace-a mixed packed bed of agglomerates of refuse incineration fly ash with cement bonded on the coke packed layer, an iron source scrap and an iron source ore, and this mixture A solvent-coke packed layer is alternately formed on the packed layer in a plurality of layers, and coke, fuel and generated CO are produced by blowing the combustion-supporting gas and fuel from the primary tuyere and the combustion-supporting gas from the secondary tuyere. Burning gas and performing continuous or batch operation to melt-reduce iron source ore while performing solvent treatment, agglomeration of iron source scrap and refuse incineration fly ash and volatilization of heavy metals in refuse incineration fly ash. And a method of producing molten pig iron and slag, and recovering molten fly ash containing heavy metals from the exhaust gas.