JP2001041659A - Coating method for refractory wall in rotary melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating method for the refractory wall in a rotary melting furnace in which lifetime of the refractory wall can be prolonged by prolonging the lifetime of a coating layer formed on the refractory wall. SOLUTION: The method for coating the refractory wall in a rotary melting furnace with refractory material while rotating the furnace comprises a step for storing molten slag to be treated in the furnace by interrupting the melting operation temporarily, a step for heating up the stored molten slag to a temperature zone higher than the normal operating temperature, and a step for supplying additive material containing a component having higher melting point than the slag to be treated into the furnace.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of coating a refractory wall in a furnace in a rotary melting furnace for melting waste and the like.

[0002]

2. Description of the Related Art In a rotary type melting furnace, an object to be treated such as waste introduced from one end is melted while moving toward the other end, and is discharged as molten slag or exhaust gas from the other end. This is a type of melting furnace using a so-called rotary kiln. Generally, rotary kilns are used for firing cement, but in recent years, rotary kilns have also been used for melting and processing incinerated ash at refuse treatment plants and dust containing valuable metals at ironworks.

[0003] When a rotary kiln is used as a melting furnace, the temperature is naturally high, so that the inner wall is made of a refractory wall such as a refractory brick. However, despite being a fire wall,
As a result of long-term operation, it is inevitable that normal or abnormal wear will occur on the refractory wall due to various causes such as melting or local heating, and at the same time, the wear of the material to be treated due to chemical reaction with the molten slag. Also occurs. Then, when the amount of wear becomes significant, it is necessary to replace the fire-resistant wall.
Replacing a refractory wall involves not only material costs and furnace construction costs, but also losses associated with furnace shutdowns (about two weeks), and dismantled refractory bricks become new waste.

[0004]

Therefore, in order to minimize the amount of wear of the refractory wall, it has been proposed to use a high-temperature refractory material or coat the refractory wall with a coating material of a refractory material. . According to this proposal, in the former case, the refractory material is expensive, and depending on the object to be treated, it is not so effective in erosion due to a chemical reaction. In the latter case, the coating operation is performed in a state where the melting process of the object is temporarily stopped. That is,
The coating material is put into a high-temperature furnace and the molten coating material is coated on the fire-resistant wall by utilizing the fact that the furnace is rotating.

By the way, as a coating material for a refractory wall of a rotary melting furnace, vitreous (main component SiO ₂ ,
Na) and earth and sand (main component SiO ₂ ) have been proposed.
However, SiO ₂ easily forms a low melting point eutectic with other metal oxides, the life of the coating layer is short, and the slag, in which a large amount of SiO ₂ is dissolved, has a high viscosity in a wide temperature range. It is difficult to make the layer thickness uniform.

Accordingly, an object of the present invention is to provide a coating method capable of extending the life of a coating layer so that the life of a refractory wall can be extended.

Another object of the present invention is to provide a coating method capable of making the thickness of the coating uniform.

[0008] Still another object of the present invention is to provide a coating method capable of effectively using a refractory material which is generated when a refractory wall is replaced in a melting furnace and is essentially waste.

[0009]

According to the present invention, there is provided a coating method for coating a refractory material in a furnace in a rotary melting furnace while rotating the furnace, wherein the melting process during operation is temporarily stopped. Storing the molten slag in the furnace by heating the molten slag to a temperature higher than a normal operating temperature; and melting the slag in the furnace to a temperature higher than the melting temperature of the processed material. Supplying an additive material containing a high content of components to a refractory wall in a rotary melting furnace.

[0010] The additive material is preferably a refractory material containing alumina as a main component.

[0011] By using, as the additive material, a crushed product of refractory brick waste obtained when disassembling a refractory wall in a furnace such as a melting furnace, it is possible to reduce waste and extend the life of the refractory wall. be able to.

The temperature range higher than the normal operating temperature is preferably in the range of 1500 to 1600 ° C.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a usual rotary melting furnace, incineration ash at a refuse incineration plant or dust generated at an ironworks is charged together with coke or coal as an object to be treated, and heated and melted. Into slag and discharged. At this time, when mainly processing the incineration ash of the refuse incineration plant, the components of the raw slag are calcia (CaO) and silica (SiO ₂ ), and the melting temperature thereof is approximately 1200 ° C.

[0014] When the object to be treated is melted in this manner, the refractory material is worn out normally or abnormally over time.

An embodiment of a method for coating a refractory wall in a rotary melting furnace according to the present invention will be described below. The coating method in the present embodiment is performed through the following steps while keeping the inside of the rotary melting furnace at a high temperature without shutting down the rotary melting furnace.
Of course, the furnace remains rotating.

The melting process, that is, the charging of the object to be processed into the furnace is temporarily interrupted, and the molten slag is retained in the furnace.

[0017] The slag temperature is set to 100 to
Raise the temperature by 300 ° C. Therefore, when processing incineration ash of a refuse incineration plant, it heats to 1500-1600 ° C.

An additive material containing alumina is gradually supplied from a waste inlet.

Then, the alumina dissolves in the slag and the melting point of the slag increases.

The molten slag in which the alumina has been melted adheres to the surface of the refractory wall (the inner peripheral surface of the furnace body) due to the rotation of the furnace, and solidifies when the melting point of the slag becomes higher than the holding temperature and becomes refractory. A coating layer is formed on the surface of the wall.

The additive material may be any refractory material containing 80 to 90% of an alumina component. In the present embodiment, a pulverized alumina-based brick waste (preferably 1 mm or less in particle size) is particularly used. Such brick debris may be brick debris generated as a waste when replacing a fire-resistant wall in a normal melting furnace, as well as brick debris generated when a fire-resistant wall is replaced in a rotary melting furnace to which the present invention is applied.

To briefly explain the above-mentioned coating principle, the molten slag in the rotary melting furnace contains SiO ₂ , CaO and Al ₂ O ₃ as main components. FIG.
FIG. 4 is a diagram showing a change in melting point according to the composition of a material mainly composed of SiO ₂ , CaO, and Al ₂ O _{3. The} melting point tends to increase as the component at each vertex increases. On the other hand, it is known that the composition of the slag of a melting furnace that treats incineration ash generated in a refuse incineration plant as a main processing object is usually in the region A of FIG. The melting point in the region A is 1200 to 14
It is in the range of 00 ° C. On the other hand, when the alumina component is increased (in the direction indicated by the arrow in FIG. 1), the melting point becomes 1500 ° C.
Rise above. Therefore, the molten slag to be treated is 150
After maintaining the high temperature of 0 ° C. or higher, preferably in the range of 1500 to 1600 ° C. to increase the saturation solubility, the coating refractory material is melted in, the viscosity is reduced, and the refractory material in the furnace is easily adhered to the surface of the refractory wall. It is the principle of the coating according to this embodiment that the solidification is finally made.

As can be seen from FIG. 1, the temperature of alumina increases to its melting point faster than other components. In other words, the time to reach the melting point is short. That is, using alumina as the coating material means that a coating layer can be formed with other components.
Further, since it is difficult to form a low melting point eutectic with other metal oxides, the life of the coating layer is prolonged.

[0024]

As described above, according to the present invention,
By using a material containing alumina as the coating material, the coating layer can be formed in a short time, and the life of the coating layer is prolonged. Also,
It is possible to reuse the brick waste generated when the fire-resistant wall is dismantled in the melting furnace, and to suppress the generation of waste.

[Brief description of the drawings]

FIG. 1 is a diagram showing a change in a melting point according to a composition of a material containing SiO ₂ , CaO, and Al ₂ O ₃ as main components.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F23G 5/00 115 F23G 5/00 115Z 5/44 ZAB 5/44 ZABD F23M 5/00 F23M 5/00 H F term (reference) 3K061 AA07 AB03 AC01 BA01 BA08 DA14 DB19 3K065 AA07 AB03 AC01 BA01 BA08 FA12 FB08 FB12 4H012 HA00 4K061 AA09 BA12 CA00 CA17 HA07

Claims (4)

[Claims] A coating method for coating a refractory material in a furnace in a rotary melting furnace while rotating the furnace, wherein the melting process during operation is temporarily interrupted, and the object slag is melted in the furnace. Retaining the molten slag of the workpiece to be retained to a temperature range higher than a normal operating temperature; supplying an additive material containing a component having a melting point higher than the melting temperature of the workpiece into the furnace. A method for coating a refractory wall in a rotary melting furnace, comprising: 2. The coating method according to claim 1, wherein the additive material is a refractory material containing alumina as a main component. 3. A rotary melting furnace according to claim 1, wherein a pulverized refractory brick waste obtained when disassembling a refractory wall in a furnace such as a melting furnace is used as said additive material. Coating method for fire-resistant walls in Japan. 4. The coating method according to claim 1, wherein the temperature range higher than the normal operating temperature is from 1500 to 1500.
A method for coating a refractory wall in a rotary melting furnace, wherein the temperature is in the range of 1600 ° C.