JPS635665B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotary kiln that can be applied to a wide range of uses such as drying, calcination, and roasting of raw materials, and in particular to a method for volatile oxidation and roasting of copper electrolytic precipitates in copper smelting. This article relates to a rotary furnace suitable for use under conditions where high temperatures and corrosive gases are generated.

Traditionally, rotary furnaces have been used for metallurgical or ceramic purposes, such as roasting, sintering, and drying for metallurgical purposes, and for producing various materials such as cement. Used for baking drying and preheating purposes. Rotary furnaces can be broadly divided into external heating rotary furnaces and internal heating (direct heating) rotary furnaces, depending on their heating method.
In the case of a direct-heating rotary furnace, the gas generated from the charge and combustion gas are mixed and discharged during heat treatment of the material charged in the rotary furnace, so it is difficult to collect and treat the exhaust gas. Problems may occur. in general,
Although the gases generated in the rotary furnace vary depending on the raw material to be charged in the rotary furnace, releasing these gases directly into the atmosphere deteriorates the working environment and is not acceptable. In addition, for example, when performing the volatilization oxidation roasting method of copper electrolytic precipitate in copper smelting in a rotary furnace, the reaction product gas contains useful substances such as arsenic, selenium, bismuth, antimony, and other useful metal substances. Efficient recovery of such reaction product gas is extremely important as it also relates to the issue of whether manufacturing costs can be significantly reduced.

Therefore, when the above-mentioned problems are considered important, an external heat type, that is, an indirect heating type rotary furnace, which can separate, recover, and process the reaction product gas and combustion gas contained in the rotary furnace is recommended. It is used. However, the general external heating type rotary furnace is a method in which the rotary furnace body is heated from the outside, and there is a problem in terms of thermal efficiency. In order to solve the drawbacks of external heating type rotary furnaces, a plurality of radiant tubes are arranged in the rotary furnace, combustion gas is fed into the radiant tubes, and the inner wall of the rotary furnace is heated by radiant heat from the radiant tubes. In addition, an indirect heating rotary furnace for heating the contents in the rotary furnace, that is, the object to be heated, has been proposed.

However, in the conventional indirect heating type rotary furnace, the radiant tube is exposed to a high temperature and a corrosive gas atmosphere in the rotary furnace, and has a drawback that its life is extremely short. In order to solve this problem, it may be possible to manufacture radiant tubes using materials that have good high-temperature strength such as creep strength or creep rupture strength, or high-temperature corrosion resistance such as thermal fatigue resistance, oxidation resistance, and carburization resistance. However, it was impossible to satisfy all of these conditions, and radiant tubes were generally considered to be expensive consumables.

As described above, in conventional indirect heating rotary furnaces, it is necessary to frequently replace the radiant tube, and each time the radiant tube is replaced, the rotary furnace must be shut down, resulting in extremely low work efficiency. It was hot.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an indirect heating type rotary furnace in which the life of the radiant tube is improved, the period of operation stoppage is eliminated, and the working efficiency is significantly improved.

Another object of the present invention is to provide an indirectly heated rotor suitable for use under conditions where corrosive gases are generated at high temperatures, such as in particular the volatilization oxidation roasting process of copper electrolytic precipitates in copper smelting. The goal is to provide a furnace.

The present invention provides a radiant tube group consisting of a plurality of radiant tubes arranged in a rotary furnace from the input side of the material to be heated to the discharge side of the rotary furnace, that is, in the longitudinal axis direction of the rotary furnace main body. This solves the drawbacks of conventional indirect heating rotary furnaces by configuring the rotary furnace body to rotate at a predetermined rotational speed and in a predetermined rotational direction independent of the rotary furnace main body. It is. That is,
In conventional indirect heating rotary furnaces, the radiant tube is held stationary within the rotating rotary furnace body, and as a result, the temperature gradient between the surface of the rotary furnace wall and the radiant tube becomes locally very large. The thermal fatigue resistance of the radiant tube may deteriorate locally, and furthermore, only certain radiant tubes tend to be exposed to high-temperature corrosive gas from the heated object, and There was a problem that particularly required high-temperature corrosion resistance.

In the present invention, the radiant tubes are rotated independently of the rotary furnace at a constant speed within the high-temperature rotary furnace, so the surface temperature gradient between each radiant tube and the rotary furnace wall is constant, and each The heat load on each radiant tube arranged in parallel is equalized. Furthermore, even when corrosive gas is generated in the rotary furnace, the continuous rotation of the radiant tubes shortens the period of exposure to the corrosive gas and averages it out in each radiant tube. As described above, in the rotary furnace of the present invention, only a specific radiant tube is not subjected to harsh temperature conditions or corrosive conditions, and the life of the radiant tube can be significantly extended compared to conventional ones.

In the rotary furnace according to the present invention, it is not preferable that the corrosive heated object or the corrosive gas from the heated object constantly contact the radiant tube in a high temperature atmosphere. The radiant tube group is arranged at a position somewhat offset from the center of the rotary furnace body. The amount of eccentricity between the center of rotation of the radiant tube group and the center of rotation of the rotary furnace body may vary depending on the amount of material to be heated and the processing capacity of the rotary furnace itself.

Furthermore, in order to increase the amount of heat radiated from the radiant tube group, it is effective to increase the number of radiant tubes constituting the radiant tube group and to attach fins to each radiant tube to expand the radiant heat transfer area.

Next, the indirect heating rotary furnace according to the present invention will be explained in more detail with reference to the drawings.

The indirect heating type rotary furnace 1 according to the present invention includes a cylindrical rotary furnace body 2 whose inner side is lined with bricks or castable refractories. The rotary furnace body 2 is rotatably held by girth ring holding means 8 and 10 with its longitudinal axis inclined with respect to the horizontal so that the heated material discharge end 4 is somewhat lower than the heated material input end 6. be done. Moreover, the rotary furnace main body 2 is the rotary furnace main body 2.
A girth sprocket 12 is provided around the periphery of the motor M1, and the girth sprocket 12 is connected via a chain 14 to a drive sprocket 16 of a drive motor M1. Therefore, the rotation of the motor M1 rotates the rotary furnace body 2 at a predetermined rotation speed in a fixed direction.
For example, in this specific example, these sprockets 1
2 and 16, the chain 14, and the motor M1 constitute a first rotating means. However, other equivalent measures may also be adopted. For example, in a rotary furnace having a diameter of 1.5 m and a length of 8 m for carrying out the volatilization oxidation roasting process of copper electrolytic precipitates in copper smelting, the rotation speed may be varied within the range of 0 to 5 rpm.

A heating device 20 is arranged on the side of the heated material discharge end 4 of the rotary furnace main body 2 . The heating device 20 includes a hot air stove 22 disposed adjacent to the heated material discharge end 4 of the rotary furnace main body 2 and a combustion device 24 . The hot air stove 22 is lined with brick or castable refractory material, and has a combustion chamber 26 inside. The internal heat furnace 30 is fixed to the side of the combustion chamber 26 facing the rotary furnace body 2, and the combustion burner 25 of the combustion device 24 is loosely fitted to the other side.

The internal heat furnace 30 has a plurality of radiant tubes 32, six in this embodiment (see FIG. 2), extending in the longitudinal axis direction of the rotary furnace body 2. It consists of a group of radiant tubes held at uniform intervals in the circumferential direction by holding plates 33 provided at appropriate locations. The inlet end of each radiant tube 32 communicates with the combustion chamber 26 and is connected to a cylindrical inlet chamber 34 fixed to the hot blast stove 22, and the outlet end of each radiant tube 32 is connected to a cylindrical outlet chamber 36.

The internal heating furnace 30 is composed of a hot air stove 22 and a group of radiant tubes integrally connected to the hot air stove 22. One end is held by a girth ring holding means 38 provided corresponding to the hot air stove 22, and the other end is held by a girth ring holding means 38 provided corresponding to the hot air stove 22. is rotatably supported by being held by roller support means 40 provided corresponding to the outlet chamber 36 of the internal heating furnace 30. Further, a girth sprocket 42 is provided around the hot air stove 22, and the girth sprocket 4
2 is connected via a chain 44 to a drive sprocket 46 of a variable drive motor M2. Therefore, by rotating the drive motor M2, the hot air stove 22
The internal heating furnace 30 is rotated at a desired rotation speed and in a desired rotation direction independently of the rotary furnace main body 2. When this rotary furnace is used to carry out the volatilization oxidation roasting method of copper electrolytic precipitates in copper smelting, and the rotary furnace main body 2 has the specifications as described above, each radiant tube has an inner diameter of 200 mm. The internal heating furnace 30 and the hot blast furnace 22 are arranged in the opposite direction from the rotary furnace main body 2.
It will be rotated at 2r.pm.

Rotation center axis O ₂ of the hot blast furnace 22 and the internal heating furnace 30
Although it is possible to configure the rotation center axis O ₁ of the rotary furnace body 2 to coincide with the rotation center axis O ₁ of the rotary furnace main body 2, as shown in FIG. It is preferable to make the rotary furnace eccentric in an obliquely upward direction from the rotation center axis _O1 of the rotary furnace main body. The amount of eccentricity can be set variously depending on the amount of material to be heated that is charged into the rotary furnace main body and the processing capacity of the rotary furnace itself. By shifting the rotational axis of the internal heating furnace 30 from the rotational axis of the rotary furnace main body 2 in this way, the time during which the radiant tube group comes into contact with the object to be heated and/or the corrosive gas from the object to be heated can be reduced. Can be done.

Furthermore, each radiant tube 32 has a third
As shown in the figure, radiant tube 32
In order to increase the amount of heat radiated from the object to the object to be heated and the furnace wall of the rotary furnace main body, a plurality of radiant tubes are provided on the outwardly facing circumferential portion of each radiant tube 32 so as to extend in the longitudinal direction of the radiant tube. In the example 3
Preferably, two fins 35 are provided.

An outlet hood 50 is provided so as to surround the connection space between the discharge end 4 of the rotary furnace body 2 and the hot air stove 22. The outlet hood 50 has a rotatable sealing means 5
2 and 54 to the rotary furnace main body 2 and the hot blast furnace 22
attached to the outer periphery of the Rotatable sealing means 52
and 54 are of the normally used packing contact sliding type;
This function allows the rotation of the cylinder and prevents gas from escaping from the connection space to the outside. The outlet hood 50 is formed with a gas outlet 56 for sucking and discharging the gas generated in the rotary furnace main body 2, and a discharge port 58 for the heated material processed in the rotary furnace main body 2. .

An inlet hood 60 is provided at the input end 6 of the rotary furnace body 2 . The inlet hood 60 is connected to the sealing means 5
The rotary furnace main body 2 and the internal heat furnace 3 are
It is attached to the outer periphery of the outlet chamber 36 of the rotary furnace body 2 and serves to prevent gas from escaping from the input end 6 of the rotary furnace body 2 to the outside. In addition, the input end 6 of the rotary furnace main body 2
A chute 66 for introducing raw materials into the rotary furnace main body 2 is provided.

The outlet chamber 36 of the internal heating furnace 30 is connected to an exhaust gas device 70 via rotatable sealing means 68 .

Next, the operation of this device will be explained.

The motors M1 and M2 are energized, and the rotary furnace main body 2
And the hot air stove 22 and internal heat furnace 30 are rotated. Generally, the rotary furnace main body 2 and the hot blast furnace 22/internal heating furnace 30 are rotated in opposite directions.

The combustion burner 25 of the combustion device 24 operates, and high temperature combustion gas is generated in the combustion chamber 26. The combustion gases are then delivered to each radiant tube 32 of the internal heat furnace 30. The radiant tube 32 is heated by the combustion gas, and uses radiant heat to heat the material to be heated that is introduced into the rotary furnace through the furnace wall of the rotary furnace main body and the raw material input chute 66. The object to be heated is transferred from the input end 6 of the rotary furnace main body 2 to the discharge end 4 while being heated by radiant heat from the furnace wall and radiant tube of the rotary furnace main body, and is discharged from the discharge port 58. On the other hand, gas generated from the object to be heated is recovered through the gas outlet 56.

The combustion gas that has flowed through the radiant tube 32 is guided to the exhaust gas device 70. A portion of the combustion gases may be circulated by circulation fan 82 through lines 80 and 74 to combustion chamber 26 to improve thermal efficiency. Valves 76 and 78 are provided in the pipes 72 and 74, respectively, to adjust the amount of circulating gas.

In the embodiment of the rotary furnace 1 according to the present invention described above, the hot blast furnace 22 is also configured to rotate integrally with the internal heating furnace 30, but when the rotary furnace 1 becomes large-sized, for example, the fourth As shown in the figure, the hot blast stove 22 is fixed, the hot blast stove 22 and the internal heating furnace 30 are rotatably connected by a heat-resistant holding means 83, and only the internal heating furnace 30 is connected to the motor M2 and the chain transmission device 84. It is also possible to configure it so that it rotates by.

In the present invention, sprockets 42 and 46, chain 44 and motor M in conjunction with FIG.
2, or a second motor for causing the motor M2 and the chain transmission 84 in conjunction with FIG. It constitutes a rotating means. However, other equivalent measures may also be adopted.

Since the indirect heating type rotary furnace according to the present invention is constructed as described above, the life of the radiant tube can be dramatically increased, and the working efficiency of the rotary furnace can be significantly improved. Furthermore, the rotary furnace of the present invention has the advantage that it can be used very effectively in heat treatments that generate corrosive gases at high temperatures.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an embodiment of an indirect heating rotary furnace according to the present invention. FIG. 2 is a sectional view taken along the line - of FIG. FIG. 3 is a cross-sectional view showing another embodiment of the radiant tube group. FIG. 4 is a longitudinal sectional view of another embodiment of the indirect heating rotary furnace according to the present invention. 1: Indirect heating rotary furnace, 2: Rotary furnace main body, 2
0: heating device, 22: hot stove, 24: combustion device,
25: Burner, 26: Combustion chamber, 30: Internal heat furnace, 3
2: Radiant tube, 33: Holding plate, 35:
Finn, 50: Exit hood, 60: Inlet hood,
70: Exhaust gas device.

Claims (1)

[Scope of Claims] 1. A cylindrical rotary furnace body which is rotatably supported with one end serving as a heated material input end and the other end serving as a heated material discharging end, and a first rotary furnace body for rotating the rotary furnace main body. an internal heating furnace comprising rotating means, a plurality of groups of radiant tubes extending along a longitudinal axis within the rotary furnace body; A hot air furnace including a combustion chamber communicating with the radiant tube at a heated material discharge end side, and a radiant tube at a heated material input end side of the rotary furnace main body for discharging combustion gas that has flowed through each of the radiant tubes. An indirect heating type rotary furnace comprising an exhaust gas device communicating with each other, and a second rotating means for rotating the internal heat furnace and the hot blast furnace together or only the internal heat furnace independently of the rotary furnace main body. 2. The indirect heating rotary furnace according to claim 1, wherein a group of radiant tubes are arranged at equal intervals on the same circumference. 3. The indirect heating type rotary furnace according to claim 2, wherein the rotation center axis of the rotary furnace body and the rotation center axis of the radiant tube group are eccentric. 4. The indirect heating type rotary furnace according to claim 2, wherein a radiation fin is provided on the outer periphery of each radiant tube.