JP2002317911A - Melting processing apparatus for waste such as incinerated ash - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make harmless waste of refractory brick involving harmful metal such as sexivalent chrome by making use of an environment of a refractory piece bed of a molten slag, and improve the economy as the refractory piece bed. SOLUTION: A melting processing apparatus comprises a melting furnace comprising a combustion chamber or a gas decomposition chamber disposed on a bottom, a grate for heating and melting slag and a refractory piece bed disposed thereon and a deposition layer of incinerated ash disposed further thereon. A refractory brick containing harmful metal discarded as waste is used for the refractory piece bed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for melting and processing waste such as incineration ash, and more particularly, to harmless refractory bricks containing toxic metals such as hexavalent chromium. The present invention relates to a processing device capable of performing a chemical treatment.

[0002]

2. Description of the Related Art As a refractory such as a brick constituting a furnace wall of a melting furnace for molten slag (hereinafter simply referred to as a refractory brick), a material containing hexavalent chromium is used. The reason is that when the refractory brick and the molten slag come into contact with each other, a slight reaction occurs between the molten slag and the refractory brick. This reaction can be suppressed as much as possible by the strong oxidizing action of hexavalent chromium and the like. However, this refractory brick is also destined to be disposed of after its useful life after about six months of continued use, and once it becomes waste material, it becomes harmful including hexavalent chromium. Therefore, conventionally, the waste material of the refractory brick containing hexavalent chromium has been subjected to detoxification treatment so that hexavalent chromium does not elute, but this detoxification treatment is complicated and extremely expensive economically. It has to be something.

The present inventor has previously proposed a "melting apparatus for waste such as incinerated ash" (Japanese Patent Application No. 11-377258). To a maximum of 100% using waste plastic as a heat source, in which refractory pieces to be used for melting slag are made of ceramic materials with excellent fire resistance. ing. Therefore, the present invention is based on the idea that the harmful metal such as hexavalent chromium is treated as much as possible by making use of the waste refractory brick containing the harmful metal such as hexavalent chromium as the refractory piece. The aim is.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned circumstances, and utilizes the environment of a refractory piece bed of molten slag to recycle refractory brick waste containing harmful metals such as hexavalent chromium. Is made harmless, and the economy as a refractory piece bed is also improved.

[0005]

According to a first aspect of the present invention, there is provided an apparatus for melting waste such as incinerated ash, wherein a combustion chamber or a gas decomposition chamber is provided at a bottom portion, and a stork and a refractory for thermally melting slag thereon. In a melting furnace in which a single bed is provided and a deposited layer of incineration ash is provided thereon, the refractory single bed is formed by using refractory bricks containing toxic metals discarded in the refractory single bed.

In a second aspect of the present invention, there is provided a melting apparatus in which a carrier air is introduced into a lower portion of the melting furnace and a fixed space for thermally decomposing waste plastic is formed by temporarily retaining molten slag. A decomposition chamber is provided, and a part of the gas decomposition chamber faces the inlet of the carrier air for carrying the waste plastic pieces, and a refractory piece bed and molten slag are dripped at the upper part of the gas decomposition chamber. In a waste melting and burning apparatus such as an incineration ash formed with a combustion and melting chamber facing an air introduction port for disposing a roster and facilitating combustion with a decomposed gas, the refractory containing a hazardous metal discarded in the refractory piece bed It is characterized by using bricks.

A third aspect of the present invention is directed to a melting apparatus, wherein the incinerated ash has a CaO / SiO ₂ ratio of 0.75 or more.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The melting apparatus according to the present invention comprises a melting furnace section 10 for melting waste S such as incineration ash and a waste plastic introducing section 30 for supplying waste plastic thereto.

A shaft-type melting furnace can be used as the melting furnace 11 in the melting furnace section, and the lower part of the melting furnace is used to receive the below-described carrier air and temporarily retain the slag G after melting. A gas decomposition chamber 12 forming a certain space is provided. A part of the gas decomposition chamber 12 is provided with an inlet 13 for the carrier air, the other side is provided with a burner 14 for performing initial preheating described later, and a lower part is provided with an outlet 15. . The inlet 13 may be used together with a relatively high-temperature air inlet pipe via a heat exchanger, as in the case of the secondary air described below. If necessary, the air may be enriched with oxygen. A vessel 19 may be provided.

On the gas decomposition chamber 12, there is disposed a roster 16 for promoting the rise of decomposition gas and dripping of molten slag. On top of that, a refractory piece bed 40 for preheating is disposed. The combustion melting chamber 17 to be filled with massive incineration ash S
To form Part of the combustion / melting chamber 17 faces a secondary air inlet 18 for promoting high-temperature combustion. The secondary air inlet 18 has a relatively high temperature through a heat exchanger with combustion gas. Air is supplied from the inlet pipe.

In the present invention, the refractory piece bed 40 is formed by cutting or rejecting waste of refractory bricks for melting furnaces containing harmful metals such as hexavalent chromium into a suitable shape as a bed. Crush and use. As mentioned above, hexavalent chromium is used in refractory bricks for the purpose of avoiding reaction with molten slag for the purpose of improving corrosion resistance, and since it is disposed of as waste after its useful life, the waste refractory For bricks. Then, the refractory brick is cut or crushed into an appropriate size to form a refractory piece bed 40. The refractory brick is used in a melting furnace and, of course, has excellent fire resistance, and if it is used as a bed, it functions as a bed for heat storage and the like in the preheating and slag melting stages described below. It will be excellent in property. And
The purpose of using waste material containing harmful metals such as hexavalent chromium in the bed is that diffusion of chromium that occurs when the slag passes through the bed in the melting stage of slag, and hexavalent chromium and the like by crystallization guided in the subsequent cooling stage of slag The aim is to detoxify harmful metals. Here, the harmful metal means, in addition to the hexavalent chromium,
It refers to ions of harmful metals such as lead, cadmium and zinc or compounds thereof.

Further, a preheating chamber 2 for preheating bulk incineration ash before combustion is provided above the combustion melting chamber 17 of the melting furnace 11.
0 is formed, and an inlet 21 for incineration ash and an exhaust port 22 for sending out exhaust gas after combustion are formed in the furnace head above it.

A transport air pipe 31 is connected to an inlet 13 of the transport air facing a part of the gas decomposition chamber 12, and a part of the pipe is cut into small pieces having a suitable shape. A hopper 32 and a fixed-rate feeder 33 for storing plastic and sending it into the carrier air are provided. A blower 34 is provided at the end of the conveying air pipe 31. When the pressure in the furnace is high, the blower is configured to apply high pressure.
In addition, the above-mentioned plastic strips include granular ones.

The object of the waste plastic as the heat source of the present invention excludes chlorinated plastics and the like which generate toxic gas such as dioxin by combustion, but can be cut or molded into other suitable sizes. Including all plastics such as tires. In addition, rice husks, wood chips, waste paper, and the like may be mixed in the waste plastic as long as the melting temperature is not significantly reduced.

Next, the operation of the device of the present invention will be described. First, incinerator ash obtained by agglomerating the incinerated ash into a bean tongue or kneading the incinerated ash with cement into an agglomerate is dropped into the melting furnace 11 from the input port 21 using a charging machine or the like. I do. However, the incinerated ash is not limited to agglomerated one, and may be supplied as a powder.

Here, in the present invention, the component of the incinerated ash is adjusted to have a CaO / SiO ₂ ratio of 0.75 or more.
This is in order to generate as many crystals as possible. That is, in the present invention, when detoxifying a harmful metal such as hexavalent chromium, the slag is melted, and the harmful metal introduced into the crystalline material is detoxified, but crystallization of the slag is promoted. In addition, the component ratio of incinerated ash is important, and CaO /
If the SiO ₂ ratio is 0.7 or less, the amorphous state is obtained, and if the SiO ₂ ratio is 0.75 or more, more crystallization is promoted. Therefore, the components of the incinerated ash are generally CaO 15-16.
_{%, SiO 2 35~36%, Al} 2 O 3 17~18%
However, in order to adjust the CaO / SiO ₂ ratio,
The CaO / SiO ₂ ratio of the incinerated ash to be charged is measured. If the incinerated ash to be charged is 0.75 or more, the incinerated ash is used as it is. If this condition is not satisfied, CaO or SiO ₂
Adjust by adding ingredients.

Then, the process proceeds to preheating, and the burner 14 is ignited to raise the temperature in the furnace.
The furnace is heated to a high temperature of about 1500 to 1800 ° C. Then, as described above, CaO, SiO ₂ , A
The incinerated ash mainly composed of l ₂ O ₃ or the like reaches the melting point, and a part of the molten slag passes through the roastle 16 and passes through the gas decomposition chamber 1.
2 is dropped on the bottom.

At that time, the combustion of the burner 14 is stopped. On the other hand, the operation of the blower 34 for sending air is started, and on the way, the waste plastic cut into small pieces of an appropriate shape is sent out from the hopper 32 into the transport air through the quantitative feeder 33, and the waste plastic is transported. It is sent into the gas decomposition chamber 12 through the inlet 13 together with air.

Then, in the gas decomposition chamber 12, since the molten slag stays at the bottom of the gas decomposition chamber 12,
When it is kept at a high temperature of １1800 ° C. and the waste plastic strip is carried by the carrier air, the plastic strip is partially burned, but most of it is thermally decomposed to a flammable gas. Metamorphose. That is, the gas decomposition chamber receives heat radiation from the molten slag staying therein, heat energy such as convection and the like, and the chamber is always kept at a temperature substantially equal to the melting temperature. Waste plastics such as are broken down at a stretch by intermolecular bonds and are thermally decomposed to change to combustible gas. As described above, under such a high temperature, if the introduced carrier air and the plastic as a combustible are present, they naturally burn, but part of the combustion and the burning of slag which will be described later. Do not hinder.

Here, the size and shape of the waste plastic to be carried in must be such that it can be pyrolyzed instantaneously and can be transported by air. Although small strips are desirable, it has been confirmed by the inventor's experiments that there is no problem with strips having a diameter of 20 mm or less.

Next, the combustible gas rises into the combustion melting chamber 17 through the hole of the rostrum 16, where it reacts with the air introduced from the secondary air inlet 18 to cause combustion. At this time, the value of the thermal calorie of the decomposed combustible gas of the waste plastic is 7000 kcal to 8000 kcal.
/ Kg, about 8000-9000 kcal
/ Kg, a very high calorie value, and the secondary air passed through the heat exchanger is kept at a relatively high temperature. Therefore, the combustion heat generated therefrom is equal to or higher than that of the conventional coke, and as a result, the massive incinerated ash smoothly reaches the melting point and becomes molten slag G.

At this time, the waste plastic is instantaneously gasified and comes into contact with the incineration ash and the like, so that it surrounds the lump incineration ash all over, and there is no danger of clogging or the like, and the combustion form suitable for melting Becomes

Combustion of waste plastics by such means requires little coke and reduces coke by 10%.
Even with 0% replacement, our experiments were successful. However, use of coke as a heat source is not denied.

Here, before passing through the roster, the molten slag flows down while contacting the refractory piece bed 40. In the course of this flow, the refractory piece bed 40 is excellent in fire resistance and does not originally react with the molten slag, but a slight reaction is inevitable, and the refractory piece bed 40 is gradually consumed. . In the course of this consumption, the harmful metal such as hexavalent chromium contained in the refractory piece bed 40 causes a diffusion phenomenon when coming into contact with the molten slag, and gradually moves into the molten slag. .

[0025] The molten slag G is
And is stored at the bottom of the gas decomposition chamber 12 and acts as a molten slag for keeping the gas decomposition chamber at a high temperature. Then, it flows down from the discharge port 15 and is transferred to the original pulverizing process or the like. It is. This step is sequentially repeated.

The molten slag flowing down from the discharge port is transferred to a cooling step. The cooling is carried out by a slow cooling method under a temperature control avoiding a granulation method or an air cooling method. Is allowed to cool gradually.

Then, the cooling step by the slow cooling and the C
By adjusting the aO / SiO ₂ ratio or the like, the molten slag forms more crystalline while avoiding the amorphous state, and harmful substances such as hexavalent chromium diffused and moved from the refractory piece bed 40 during the crystallization process. The metal component is also mixed into the crystal and participates in the formation of new crystalline material. That is, the components of the incinerated ash are approximately 15 to 16% of CaO and 35 to 35% of SiO ₂ .
_36%, consists of _Al 2 O 3 17-18% Adjusting these CaO / SiO ₂ ratio of 0.75 or more, if these components are once melt at a temperature of 1,300 to 1,800 ° C., subjected to subsequent cooling A process of producing new crystals from the melt is created. As a result, harmful metal components such as hexavalent chromium are taken into the new crystalline material, and are in a form that is not easily eluted outside, that is, a harmless form.

Although the incineration ash has been described as an example of the object to be treated, the invention is not limited to such waste as long as it can be treated according to the same principle. It can be widely applied to metal scraps and others.

[0029]

Test Example In a melting treatment apparatus, a waste refractory brick containing chromium having a composition shown in Table 2 was used as a refractory piece bed, and incineration ash having a composition shown in Table 1 was put into the bed and melted. Then, the melted slag was gradually cooled while applying heat, and a dissolution test was performed on the treated product after the cooling and solidification. The results are shown in Table 3, where C
An undetected result could be obtained on the basis that r ^{+ 6} is 0.005 or less, and it was confirmed that hexavalent chromium was detoxified.

[0030]

[Table 1] <Slag composition>

[0031]

[Table 2] <Composition of waste refractory bricks>

[0032]

[Table 3] <Dissolution test results>

[0033]

The present invention has the following effects based on the above configuration and operation. (1) Waste such as incinerated ash can be used in a melting treatment device, and waste of refractory bricks containing harmful metals such as hexavalent chromium, which has been difficult to treat, can be used for refractory piece beds, and In the melting process, the slag promotes the crystallization of the molten slag and can be rendered harmless.

At this time, if the CaO / SiO ₂ ratio of the incinerated ash is set to 0.75 or more, the conditions under which harmful metal components such as hexavalent chromium are taken into new crystals are improved.

(2) If necessary, all of the waste plastic can be replaced with waste plastic without using coke as a heat source, so that the energy cost can be greatly reduced. Instead of burning as it is, once, it is thermally decomposed at high temperature to a combustible gas, and it is burned by mixing with secondary air while surrounding the object to be treated, so that the contact efficiency can be made very good .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of the device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Melting furnace part 11 Melting furnace 12 Gas decomposition chamber 13 Carrier air inlet 14 Burner 15 Outlet 16 Rostor 17 Combustion melting chamber 18 Secondary air inlet 19 Oxygen enricher 20 Preheating chamber 21 Input port 22 Exhaust port 30 Disposal Plastic introduction section 31 Conveying air pipe 32 Hopper 33 Metering machine 34 Blower 40 Refractory piece bed

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F23G 5/44 F23J 1/00 B F23J 1/00 B09B 3/00 303L F term (reference) 3K061 AA16 AB02 AB03 AC03 AC13 AC14 BA05 BA09 CA01 DA12 DB16 DB17 FA21 FA25 FA26 FA27 NB03 3K065 AA16 AB02 AB03 AC03 AC13 AC14 BA05 BA09 EA12 GA03 GA13 GA22 GA23 GA33 GA34 4D004 AA07 AA37 AB03 CA27 CA29 CA32 CB04 CB34 CB50 CC02 DA03 CA10 A13A25 CA10 CA62 CA64

Claims (3)

[Claims] 1. A melting furnace in which a combustion chamber or a gas decomposition chamber is provided at a bottom portion, a roster for thermally melting slag and a refractory piece bed are provided thereon, and a deposition layer of incineration ash is provided thereon. An apparatus for melting waste such as incinerated ash, wherein refractory bricks containing harmful metals disposed of in the refractory piece bed are used. 2. A gas cracking chamber having a fixed space for thermally decomposing waste plastic by introducing conveying air into the lower portion of the melting furnace and temporarily retaining the slag after melting, and A part of the gas decomposition chamber faces the inlet of the carrier air for carrying waste plastic strips, and a refractory piece bed and a roster for facilitating the dripping of molten slag are arranged at the upper part of the gas decomposition chamber. A combustion melting chamber formed with a combustion-melting chamber facing an air introduction port for promoting the combustion of air, characterized in that a fire-resistant brick containing toxic metals disposed of in the refractory piece bed is used in the refractory piece bed. Melt processing equipment. 3. The incinerated ash has a CaO / SiO ₂ ratio of 0.7.
The melt processing apparatus according to claim 1, wherein the number is 5 or more.