JPH07150264A - Classification treatment of high-temperature meltable material - Google Patents

Abstract

PURPOSE:To reduce the amt. of coke to be used and to execute the efficient melting and classifying treatment of high-temp. meltable materials by charging the high-temp. meltable materials, the coke adjusted in grain size and moldings composed mainly of a thermosetting resin partly contg. air into a melting furnace. CONSTITUTION:The high-temp. meltable materials, such as slug in a blast furnace and foundry pig iron, the coke adjusted in grain size to about 15 to 100mm and the moldings composed of the dis-sociated and thermosetting resins (polyethylene, etc.,) as a base and adjusted in shape by integrating and molding the resins so as to partly contain the air are charged into the melting furnace and the high-temp. meltable materials are so melted that the moldings exist positively in an oxidation zone. Generated high-heat gases are discharged from the furnace top and are captured and treated in post stages. The high-heat retreated melts are taken out of the furnace bottom and are separated and cooled so as to be utilized as industrial resources. As a result, the amt. of the coke to be used is saved and the melting rate is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to the use of coke, which is the main fuel, in a specific melting furnace for inorganic oxides, metal compounds, etc. The present invention relates to a method for efficiently dissolving and separating the high-temperature meltable material by lowering it.

[0002]

2. Description of the Related Art Conventionally, a metal oxide such as iron ore and an inorganic oxide such as blast furnace slag and cast pig iron, and a substance such as a metal compound which melts at a high temperature are easily processed and melt-processed, One of the major fields in the method of separation and treatment is coke as a fuel heat source, and the equipment is usually a vertical melting furnace whose water is cooled in the surroundings. It goes without saying that they make a considerable contribution. Further, as a measure for improving the technology, reduction of fuel cost, in particular, as means for reducing the coke usage ratio, heavy oil injection into the furnace, fine coal injection (PCI device), injection of fine coke by injection, etc. Various concrete measures are being implemented. Further, in the structure of the melting furnace, in order to increase the thermal efficiency of the charged raw material, a system for installing a preheating device for the raw material by heat recovery, or a system in which the furnace height of the melting furnace is increased to perform heat exchange in the furnace Has also been adopted. As such, steelmaking dust is reduced and smelted in a rotary kiln, etc., and the easily vaporized oxide dust containing zinc as a main component is separated from iron, and this oxide dust is used as a raw material for valuable metals. A method of recovering and utilizing it is proposed (Japanese Patent Laid-Open No. 60-162).
736, Japanese Patent Publication No. 59-2861). Also,
Japanese Patent Application Laid-Open No. 4-147927 proposes a method of collecting oxide dust obtained by calcination in a rotary kiln and treating the collected oxide dust by a wet method to purify and recover high-purity zinc oxide. As a similar method, JP-A-5-2024
In Japanese Patent No. 36, No. 36, the oxide dust obtained by melting in a rotary kiln is collected, a necessary amount of aluminum refining residual ash is mixed with the collected oxidation dust, and the mixture is lumped, and then 800 to 12
A method of recovering metallic zinc that is heated to 00 ° C. and volatilized has been proposed. Japanese Patent Laid-Open No. 2-263088 proposes a method of repeatedly introducing the powder generated in the cupola and the metal and / or oxide contained in the powder into the cupola to concentrate the powder. . Furthermore,
Japanese Unexamined Patent Publication No. 3-265559 relates to a zinc oxide raw material for a voltage non-linear resistor, but describes a method for producing zinc oxide. Among them, S in zinc oxide is described.
As a method of removing iC impurities, metallic zinc melted in a melting furnace is put in a retort furnace and heated to about 1100 to 1400 ° C., so that zinc is evaporated and burnt and oxidized to become zinc oxide. It is described that the zinc oxide is collected in a collection duct after cooling.

[0003]

However, when the rotary kiln is used for smelting, the semi-molten material in the rotary kiln adheres to the inner wall of the rotary kiln, so that a ring is gradually formed, and finally the molten metal is melted. It will not be able to be baked. Therefore, it is necessary to install a ring removing device in the rotary kiln or to remove the ring by jet injection by stopping the rotary kiln, which causes a problem that continuous operation cannot be performed. When using a cupola, continuous operation is possible without forming a ring like a rotary kiln,
Since the product is simply repeatedly introduced into the cupola, the purity of the obtained product is at most 10 to 95% by weight, and since it contains impurities, it cannot be used as it is as a zinc oxide raw material. In addition, JP-A-3-26
Si as an impurity by the method described in Japanese Patent No. 5559.
Although C could be removed, the secondary ash of municipal waste, which is the object of the present invention, contains the above-mentioned impurities and chlorine compounds in addition to these, so if these are not removed at the same time, For example, there is a problem that zinc oxide cannot be used as a product in a refining process or as a raw material.

[0004]

Therefore, as a result of intensive investigations by the present inventor to solve the above problems,
When melting high-temperature meltable substances in a melting furnace, use solid fuel that is compression molded by adding crushed or cut films such as polyethylene, polypropylene, polystyrene, etc. Awareness The present invention has been completed. That is, the present invention, a high-temperature meltable, a coke having a particle size adjusted, and a molded product obtained by intensively molding and shaping the thermoplastic resin once dissociated and divided as if it contains a part of air. Or separately charging into the melting furnace, melting the high temperature fusible material so that the above-mentioned molded product is positively positioned in the oxidation zone of the melting furnace, taking out the molten material from the furnace bottom and high heat from the furnace top. It is a method for separating and treating a high temperature meltable material, characterized by discharging gas.

The present invention will be described in detail below. The high temperature fusible material of the present invention is one that melts at a high temperature, for example,
Blast-furnace slag, which is mainly for melting treatment, that rapidly cools the slag that is generated when pig iron is produced by charging secondary ash, iron ore, coke, and limestone that remain after incinerating municipal solid waste into a blast furnace. Further, cast iron and the like can be mentioned. In addition, a reduction reaction occurs in parallel with melting, and as an object of dissolution and separation treatment of a target substance and other substances, iron ore, manganese ore, zinc ore, and further waste such as converter dust, electric furnace dust, etc. Can be mentioned.

[0006] These high-temperature meltable substances are charged into a melting furnace. At this time, as a heat source, coke whose particle size has been adjusted, and on the other hand, as a heat source, as a spacer, a dissociated and divided thermoplastic resin is used as a base. At the same time or separately, the molded product whose shape is adjusted by intensive molding as if it partially contains air is charged. As coke, there are foundry coke, blast furnace coke, non-ferrous metal refining coke, and other uses of coke, but casting coke having a particle size adjusted to 15 to 100 mm in consideration of combustion efficiency in a melting furnace is used. Preferably. This high-temperature meltable substance may contain a substance that generates a toxic gas when it is subjected to high-temperature treatment. In the case of such a high-temperature meltable substance, a chemical treatment for removing them is performed beforehand. It is preferable. As the chemical treatment, conventionally known ones can be used. For example, chlorine content may be subjected to alkali neutralization treatment, and sulfur content may be subjected to heating, adsorption treatment, or the like.

[0007] A molded product which is formed by aggregate molding based on a dissociatively cut thermoplastic resin as if it contains a part of air, is a discarded plastic, that is, a film of polyethylene, polypropylene, polystyrene or the like, It is a crushed or chopped sheet-like material and compression-molded by adding paper scraps, wood scraps, etc.This resin should rather be discarded and what is usually called waste plastic is sufficient, and , Economical. It is mainly used as a solid fuel. It is particularly preferable to use a thermoplastic resin as a main component, but
It is more preferable to contain 0% by weight or more. This waste plastic molding fuel (hereinafter also simply referred to as waste plastic) is a heat source,
Since it plays a role as a spacer,
The shape may be adjusted so that the mixture with coke in the melting furnace is improved. This is particularly preferable in the case of a melting furnace in which combustion air is blown from near the bottom of the furnace, and it is preferably about 15 to 100 mm from the viewpoint of combustion efficiency. One of the reasons for using this waste plastic is energy saving, and the other purpose is to utilize the high heat generated by the waste plastic when it burns. This is because the melting work is facilitated and the oxidation and reduction reactions are promoted, and other purposes are consumption of waste plastic and reduction of coke consumption.

As the melting furnace, a normal structure having a water cooling pipe inside or a structure having a water cooling jacket around it can be used. However, as in the present invention, a waste plastic which generates high heat by combustion is used. When used or inside the furnace at 1000 ° C
When the temperature is higher than a certain level, the one provided with a water cooling jacket is more preferable in that the surrounding bricks are not melted. For example, a water-cooled blast furnace cupola furnace system having a high heat resistance around its periphery can be given.
The reason for using the melting furnace is that it can be operated continuously because there is no ring formation as in a rotary kiln, it can collect volatile components from the top of the furnace with good yield, and It is possible to recover metallic iron.

The coke having the adjusted particle size and the waste plastic are supplied to the melting furnace. At this time, they may be supplied separately or may be mixed before being supplied to the melting furnace. . The supply ratio of coke and waste plastic is preferably about 20 to 60% by weight with respect to coke in the rock wool manufacturing process, and about 30% by weight in the case of casting. However, it is preferable to appropriately change it depending on the properties of the high temperature meltable material. The coke and waste plastic supplied to the melting furnace are burned by the preheated air supplied from the lower part of the melting furnace, and the temperature inside the furnace rises to a predetermined temperature. Here, the high temperature fusible material is continuously supplied from the furnace top. In this melting furnace, in order to process the high-temperature meltable material more efficiently, it is preferable that the waste plastic is located in the positive oxidation zone, and also for the waste plastic to function as a heat source and a spacer. Therefore, it is preferable that the contact area with the combustion air supplied from the bottom of the furnace is increased. Specifically, there are measures such as lowering the furnace height of the melting furnace, increasing the furnace diameter, or not thickening the layer of the high-temperature meltable material, and these methods can also be performed alone,
It can also be used together. Therefore, the layer block of each charge also has a relatively short layer thickness from the charge to the dissolution zone and, in some cases, the reduction reaction zone. This positively positions the initial charge in the oxidation zone, causes a combustion reaction by the resin, and contributes to preheating of coke and other charges. The positive oxidation zone referred to in the present invention is mainly the oxidation zone in the upper part of the furnace, while the lower zone is mainly the reduction reaction zone. In this aggressive oxidation zone, the high temperature fusible material charged from the furnace top, which contains a metal component, undergoes an oxidation reaction by coke. Then, in order to promote combustion in a limited furnace, air or oxygen may be fed into the furnace through a lance pipe. Here, it undergoes an oxidation reaction and is processed, and impurities such as contained metal components become high-heat exhaust gas and are discharged from the furnace top. For example, in the case of metallic zinc in electric furnace dust, it is oxidized and reduced to zinc oxide here, taken out from the furnace top as high-heat exhaust gas, and collected and treated in a later step.
The high-temperature reprocessed melt from which impurities have been removed is extracted from the bottom of the furnace, separated and cooled, and then iron is recovered, and part of it is used as an industrial material.

The high-temperature exhaust gas discharged from the furnace top is
Since it contains gas of metal components, suspended particles with large particle size, and fluffy waste plastic that could not be completely extinguished, these were used for the purpose of recovering effectively usable components and treating harmful substances that cannot be released into the atmosphere. Need to be collected. As a method of collecting, of course, first, a suspended matter having a large particle size is collected. A cyclone, a water-cooled spray, a dust collector or the like can be used as the collecting device used here. The substances collected here include oxides of zinc, lead, cadmium and the like in the treated high temperature meltable substance and chlorides thereof. The oxide and the like collected here can be reused as a raw material for zinc oxide, for example, by subjecting it to a secondary treatment. As the method of the secondary treatment, the oxide is obtained as a clinker from the furnace bottom by introducing it into a rotary kiln or the like and performing heat treatment,
One of the chlorides is recovered in gaseous form from the furnace inlet.

[0011] In addition, it was not collected by the collection device,
High-heat exhaust gas contains unburned, fluffy, small pieces of waste plastic that could not be completely extinguished, and if sent to the subsequent process as it is, it will become an ignition source and lead to burning of equipment such as bag filters. Therefore, it is preferable to use a wet electrostatic precipitator to completely extinguish the fire and collect the fire. The collected fine metal component can be effectively used in the same manner as the metal component.

Regarding the exhaust gas passing through the collector,
It is preferable to diffuse into the air or, if necessary, to carry out a chemical treatment such as an alkali neutralization treatment.

Although the general processing method has been described above, a specific example used in the manufacturing process of rock wool will be described. In a normal rock wool manufacturing process, air-cooled blast furnace slag mass, silica stone, and coke are uniformly melted in a melting furnace, and then the melted product is extracted from the lower part,
This melted material is made into fibers having an average diameter of about 4 μm by a fiberizing device and collected in a cotton collection room to obtain rock wool products. In rock wool production, coke is usually used as the fuel. Further, when the blown air is heated in advance, kerosene, heavy oil or the like is used as the energy by providing a separate hot air stove. In the present invention, in order to reduce the amount of coke used as a fuel for melting cupola, a part of the coke can be replaced with waste plastic, and the production cost of rock wool can be reduced.

Next, the case of melting a casting will be described. In the melting of a casting in a cupola furnace, coke (injection coke) and metal are usually charged alternately in layers. The charged coke and bullion are heated in the pre-tropics,
Coke starts burning in the lower pretropical zone. Further, the metal enters the melting zone and the metal is melted, and the melt passes through the hypertrophic zone composed of bed coke, enters the hot water pool zone, and is taken out from the tap. On the other hand, most of the driven-in coke burns and is consumed in the pretropical zone and the melting zone, but a part of it reaches the hypertrophic zone and is replenished as bed coke.
In this case as well, by using a solid fuel made of waste plastic for a part of the coke as in the rock wool manufacturing process, it is possible to improve the dissolution efficiency of the metal and reduce the cost. Waste plastic burns in the pretropics and contributes to the effective preheating of the bullion. As a result, it facilitates the dissolution of the metal in the next dissolution zone, and has a great effect on the improvement of the dissolution rate. Further, it is preferable to increase the amount of blown air by about 20 to 30% in order to burn the waste plastic.

Further, the case of application to electric furnace dust will be described. In a steel manufacturing method using scrap iron (scrap) as a main raw material, an electric furnace (arc furnace) is usually used for melting. In the steel making process of this method, about 15 kilograms of dust (hereinafter referred to as electric furnace dust) are produced per ton of steel as a product, which is collected by a bag filter or an electrostatic precipitator. The chemical composition of electric furnace dust is shown in the table below. As shown in the table, the electric furnace dust contains 24-32% of zinc and is recovered as a zinc resource. The most commonly used recovery method is to heat and sinter in a rotary kiln using carbon or anthracite as a reducing agent to vaporize metals such as zinc,
This is a technique for recovering this as crude zinc oxide and further refining it to obtain zinc oxide, which is generally called the Welshon method. This process is a technology widely adopted not only in Japan but also in other countries. However, in the above-mentioned Weltz kiln method, a phenomenon in which semi-molten electric furnace dust adheres to the inner wall of the kiln (called a dam ring or simply a ring) often occurs during kiln operation, and it takes a lot of time to remove it. However, the recovery rate of zinc also varies. The present invention is based on a completely different process for compensating for the above-mentioned defects. First, the electric furnace dust is treated with an alkaline solution to remove the chlorine content in the electric furnace dust, and then granulated and dried to obtain a vertical mold. A coke and waste plastic are charged into a furnace (cupola), melted and reduced, volatile metals such as zinc are taken out as oxides from the upper part of the cupola together with high temperature exhaust gas, and are collected by a bag filter or an electrostatic precipitator. For granulation here, briquetting with a briquette machine, pelletization with pelletizing, and the like can be used. Specifically, the electric furnace dust is neutralized with a caustic soda solution in an amount (equal amount) commensurate with the chlorine content in the electric furnace dust, washed with water to remove chlorine, and the water content is set to 1
The material adjusted to 5 to 20% is granulated with a briquetting machine into a briquette having a long side of about 45 mm (referred to as briquette). Since the electric furnace dust treated with alkali in this way has an adhesive force by itself, it can be made into a briquette without adding a binder or the like to the grits.

[0016]

【Example】

Examples 1 and 2, Comparative Example 1 FIG. 1 is a flow sheet of a rock wool manufacturing process.
The raw fuel hopper 1 has an air-cooled blast furnace slag mass (hereinafter simply referred to as slag) having a particle size of 25 to 50 mm and a particle size of 10 to 40 m.
m silica stone (hereinafter simply referred to as silica stone), grain size 25 to 50 mm
The coke and the thermoplastic resin extruded into a shape of 40φ × 40 to 120 mm in diameter are stored. These raw fuels are continuously weighed or intermittently charged into a water-cooled vertical melting furnace (hereinafter simply referred to as cupola) 3 by a conveyor 2, in which the slag and silica stone are uniformly melted, and the cupola is melted. Hot water (melted material) is discharged from the lower part of 3, and the hot water is made into fibers having an average diameter of about 4 μm by a fiberizing device 4, collected in a cotton collection chamber 5, and further passes through a processing device (purification / packing) 6. It becomes a rock wool product. On the other hand, the exhaust gas discharged from the upper part of the cupola 3 is the exhaust gas washing device 8
It is washed with water and then dedusted by an electric dust collector 9, and further, a sulfur content is removed by a desulfurization device 10 and is passed through a chimney 11 to be released into the atmosphere. A steel water-cooled cupola facility was used as a vertical melting furnace in this process. The furnace has a relatively wide inner diameter and a relatively low furnace height compared to the new cupola facility. The specific specifications of the furnace are as follows. Furnace bottom inner diameter 1,300 mm, furnace height 4,700 mm, 20 tuyeres Here, in order to reduce the amount of coke used as the fuel for melting cupola, solid fuel of waste plastic was used. The results are shown in Table 1.

[0017]

[Table 1] In Table 1, Comparative Example 1 is an ordinary method in which only coke is used as fuel without using waste plastic as cupola fuel. The coke weight ratio to the raw material, that is, the coke ratio, is 1
It is 3.5%. On the other hand, Example 1 and Example 2 used waste plastic as fuel together. In Example 1, when the waste plastic was 290 kg / hr, the coke consumption was 47.
Only 0 kg / hr was required, and the coke ratio was 10.1%, which was 3.4% lower than in normal operation. 3.0% in Example 2
Reduced. The production speed of rock wool was also the same as usual. The reduction amount of coke can be saved about 43 kg per ton of rock wool, which contributes to the reduction of manufacturing cost.
Moreover, it is possible to burn waste plastic waste.

Examples 3 to 4 and Comparative Example 2 In melting a casting in a cupola furnace, a thermoplastic resin extruded into a shape of about 40φ × 40 to 120 mm was used as a fuel together with coke as a fuel. Further, the amount of air blown was increased by about 20 to 30% to burn the waste plastic. The following cupola for casting was used for melting the metal. Cupola specifications Furnace inner diameter 950 mm Furnace cross-sectional area 0.71 m ² Tuyere ratio 8 (tuyer number) Furnace height 4,400 mm Table 2 shows the results of the melting experiment.

[Table 2] In Table 2, Comparative Example 2 uses only coke as a fuel, and has a metal dissolution rate (= metal charging rate) of 5,600 (kg / hr) and a coke ratio of 0.121. In Example 3, about 30% of waste plastic was used as an additional fuel for coke, and as a result, the melting rate was improved by about 20%. Example 4 is for coke 4
Although the data are obtained when 0% of the waste plastic was additionally used, the degree of improvement in the dissolution rate was the same as in Example 3. The combined use of waste plastic as fuel did not contribute much to the improvement of the coke ratio.

Example 5, Comparative Example 3 In the steelmaking method using scrap iron (scrap) as a main raw material, about 15 kilograms of dust (hereinafter referred to as electric furnace dust) is produced per ton of steel as a product. Table 3 shows the chemical composition of the electric furnace dust.

[Table 3] The electric furnace dust is subjected to neutralization treatment with an amount (equivalent amount) of caustic soda solution commensurate with the chlorine content in the electric furnace dust, washed with water to remove chlorine, and the water content adjusted to 15 to 20% is briquette. It was granulated with a machine into a charcoal-like product having a long side of 45 mm. In addition, electric furnace dust treated with alkali in this way is
Since it has adhesiveness by itself, it could be made into a briquette without adding a binder or the like. The specifications of the cupola used to fulfill the present invention are as follows. Inner diameter of furnace bottom 1,300 mm Height of furnace 4,700 mm 20 tuyeres Melting by cupola was performed with and without waste plastic. The results are shown in Table 4.

[0020]

[Table 4] In Table 4, dust was molded into a briquette and charged into a cupola. In Comparative Example 3, waste plastic was not used as the fuel, that is, only coke was used as the fuel. At this time, the coke required for the smelting reduction of dust was 2,630 kg / h.
It was 649 kg when expressed as a coke ratio by r. On the other hand, in Example 5, when waste plastic was used as the fuel, the coke consumption was 1,250 kg and the coke ratio was 410 kg, and the coke consumption was significantly reduced. The chemical composition of the crude zinc oxide obtained in the examples of Table 4 is as shown in Table 5, and there was no particular difference between the case where the waste plastic was used as a fuel and the case where it was not used. Further, the chlorine content of the obtained crude zinc oxide was less than 1%, and it could be sufficiently recycled as a raw material for zinc refining.

[Table 5]
(%)

[0021]

As described above, according to the present invention, among known devices, methods, and operating surfaces, a thermoplastic resin such as polyethylene, polypropylene, or polystyrene, which has been once dissociated and cut, is used as a base. By putting what is collectively molded so that it partially contains air into the melting furnace together with the coke, there is a remarkable effect that the amount of coke used can be reduced or the melting rate can be improved.

[Brief description of drawings]

FIG. 1 is a flow sheet of a rock wool manufacturing process.

[Explanation of symbols] 1 raw fuel hopper 2 conveyor 3 vertical melting furnace 4 fiberizing device 5 cotton collection chamber 6 processing equipment 7 wet dust collector 8 exhaust gas washing device 9 electric dust collector 10 desulfurization device 11 chimney

Claims (2)

[Claims] 1. A high-temperature fusible material, a coke whose particle size has been adjusted, and a molded product whose shape has been adjusted by intensively molding a thermoplastic resin that has been once dissociated and fractionated into a base and contains a portion of air therein. Alternatively, they are separately charged into a melting furnace to melt the high-temperature meltable material so that the molded product is positively positioned in the oxidation zone of the melting furnace, take out the molten material from the furnace bottom, and heat it higher than the furnace top. A method for separating and treating a high-temperature fusible material, which comprises discharging gas. 2. After removing harmful substances contained in the high-temperature meltable material in advance, granulating and drying the coke, and a thermoplastic resin once dissociated and fractionated is used as a base, which partially contains air. The method for separating and treating a high-temperature meltable product according to claim 1, wherein the molded product, which has been subjected to intensive molding and shape adjustment as described above, is charged into a melting furnace.