JPH0741321A - Roasting furnace for production iron oxide - Google Patents

Abstract

PURPOSE:To stabilize the quality of an iron oxide product and continuously operate the furnace for roasting a waste pickling soln. of a steel sheet to produce iron oxide by providing a means for removing the iron oxide depositing around a hot air blowing port. CONSTITUTION:Waste hydrochloric acid produced from a steel sheet pickling stage is sprayed into a roasting furnace 4 from a spray header provided at the top of the furnace 4, hot air is simultaneously blown in toward the top from the hot air blowing port 16a of a hot air blowing means at the bottom of the furnace 4 to produce a hot air spiral flow for roasting the waste hydrochloric acid supplied from the spray header, and the hot air is discharged from a discharge port. The formed iron oxide is recovered from a recovery part. An iron oxide removing means 20 furnished to the periphery of the blowing port 16a is periodically operated to rotate a blade 21 along the inner wall of the furnace 4 through a driving means 22, and the iron oxide 19 depositing around the hot air blowing port 16 is removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roasting furnace for producing iron oxide, and by preventing the formation of iron oxide lumps on the inner wall side of the roasting furnace at the hot air blowing port, the hot air in the roasting furnace is prevented. The present invention relates to a roasting furnace that stabilizes the quality of iron oxide produced by constantly performing a normal swirling flow and enables continuous long-term operation of the equipment.

[0002]

2. Description of the Related Art As shown in FIG. 1, a hydrochloric acid recovery facility for recovering hydrochloric acid and producing iron oxide by concentrating and roasting the waste hydrochloric acid generated in the pickling process of a steel sheet is constituted by the following flow. ing. The hot gas from the outlet 17 from which most of the iron oxide has been removed by the cyclone 3 is guided to the cleaning tower 2. Waste hydrochloric acid 1 generated in the steel sheet pickling process is roasted in the roasting furnace 4 in the cleaning tower 2.
After the heat is exchanged with the hot gas 15 and concentrated, it is sprayed from the spray header 6 into the roasting furnace 4 from the top 5 of the roasting furnace. In the roasting furnace, the hot air 7 forms a swirl flow 8 in the roasting furnace, and iron oxide and HCl gas are generated by the following reaction formula. 2FeCl ₂ + 1 / 2O ₂ + 2H ₂ O → Fe ₂ O ₃
+ 4HCl 2FeCl ₃ + 3H ₂ O ────── → Fe ₂ O ₃
+ 6HCl

As shown in FIG. 2, the produced iron oxide has a falling material 9 at the center of the roasting furnace and a falling material 10 falling along the inner wall of the roasting furnace, and falls toward the recovery port 18. . As a method of attaching the hot air blowing means 16, the hot air 8 swirling in the roasting furnace 4 along the inner wall of the roasting furnace 4 as shown in FIG.
The opening is tilted tangentially to the inner wall of the roasting furnace in order to form the direction of the blowing port (angle 14 with the tangent line 11 of the inner wall of the roasting furnace).
For large roasting furnaces,
It is smaller in a small roasting furnace, and is approximately 8 to 30 degrees, although it depends on the size of the roasting furnace.

FIG. 4 shows an enlarged view of the blowing port 16a of the blowing means 16 for blowing the hot air 7. The blowing velocity of the hot air 7 is 2
0 to 40 m / sec, which varies depending on the size and size of the roasting furnace and operating conditions, but in any case, when hot air in the roasting furnace with a large cross-sectional area is blown out from the hot air blowing port 16a with a small cross-sectional area, A stagnation 13 is formed between the blowing air inlet 16 a and the inner wall 12 of the roasting furnace. The stagnation 13 entrains the falling material 10 that drops along the inner wall of the roasting furnace to the bottom of the roasting furnace, adheres to the inner wall of the body of the roasting furnace, and the adhered material repeatedly melts and adheres in a high temperature hot air atmosphere. Finally, the hot air blowing port 16a is also covered to prevent the blowing of hot air into the furnace.

Therefore, the hot air 7 in such a state does not form a normal swirling flow 8 and diffuses throughout the roasting furnace. As a result, the roasting reaction in the roasting furnace becomes abnormal, and the quality of the iron oxide, for example, the Cl ⁻ content contained in the iron oxide and the powder characteristic values such as the compression density deteriorate.

In such a case, if the purpose is to treat only waste hydrochloric acid, continuous operation for 1 to 1.5 months is possible, but in order to satisfy the quality of iron oxide as well, 1
Continuous operation for less than a month is the limit. As a conventional technology,
As in Japanese Examined Patent Publication No. 54-28626, only the quality of iron oxide, particularly the Cl ⁻ content contained in iron oxide is focused on, and no consideration is given to long-term operability.
Further, in JP-A-62-106287, the attachment angle of the hot air blowing port is described as a cause of the adhesion phenomenon due to these stagnation, but this method also does not completely avoid the stagnation phenomenon. It is difficult to think, and therefore, it is unlikely that it will continue to stabilize the quality of iron oxide and the operation, and it is considered unrealistic.

In Japanese Patent Laid-Open No. 02-145438, there is proposed a method in which a ceramic sprayed body is provided on the inner wall of the furnace and the deposit is easily removed by a high pressure gas injection nozzle during actual operation without depending on the input. Even if partial removal is possible by this method, it is considered difficult to maintain the normal state of the hot air flow. In addition, JP-A-4-292
No. 788 proposes removal of deposits in the furnace when the operation is stopped, but there is a problem in that consideration is not given to performing it during continuous operation.

[0008]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above problems, in which waste hydrochloric acid discharged from the pickling step of a steel sheet is concentrated and roasted to recover hydrochloric acid and produce iron oxide. In the iron oxide production roasting furnace of the hydrochloric acid recovery equipment that performs
Preventing iron oxide lumps from adhering and forming around the inside of the hot air blowing port furnace, and as a result, always obtaining a normal and uniform hot air swirling flow, stabilizing the quality of iron oxide, and regarding the roasting furnace. It is an object of the present invention to provide a roasting furnace capable of performing stable continuous operation for more than a month.

[0009]

That is, the present invention is directed to a roasting furnace main body, a spray header provided on the top of the roasting furnace main body so as to spray waste hydrochloric acid generated in the pickling step of a steel sheet, and a roasting furnace. A hot air blowing means that is provided near the bottom of the furnace body and that generates a hot air swirl flow for roasting the waste hydrochloric acid sprayed from the spray header from the vicinity of the roasting furnace bottom to the nip, and this hot air swirl flow is discharged. In a roasting furnace having a discharge port for heating and a recovery port for iron oxide formed by roasting and oxidizing by a hot air swirl flow, the hot air blowing means has a hot air blowing port peripheral portion opening to the roasting furnace main body. The present invention provides a roasting furnace for producing iron oxide, which is provided with a means for removing attached iron oxide around the hot air blowing port. The oxide removing means is preferably constituted by a blade or a brush that can be rotated along the inner wall of the roasting furnace main body around the hot air blowing port, and the rotation drive may be manual or automatic.

[0010]

The present invention will be described in more detail below. As described with reference to FIGS. 2 and 4, the iron oxide particles generated by spray roasting of waste hydrochloric acid start to adhere to the inner wall of the roasting furnace main body in the hot air stagnation 13 generated near the hot air outlet 16a, and gradually. As described above, the swirl flow 8 is disturbed as it is accumulated on the surface and is blocked, which adversely affects the production of iron oxide.

In view of this, in the present invention, a means for removing the iron oxide that has adhered and accumulated near the hot air outlet of the roasting furnace is provided, and this is operated periodically to roast the iron oxide block 19 that has adhered. It is removed from the inner wall of the furnace body so that a stable hot-air swirl flow is always formed, and iron oxide with stable quality can be produced for a long period of time.

An example of the structure of the oxide removing means 20 is shown in FIG. On the inner wall of the roasting furnace 4 above the hot air outlet 16a, a blade 21 rotatable along this is installed. This blade moves from the drive means 22 to the reduction gear train 2
3 and the drive shaft 24. The operation of the oxide removing means may be performed periodically or periodically to operate the driving means 22, or may be performed depending on the state of adhesion of the oxide to the inner wall of the furnace body. This actuation control may be automatic or manual. In any case, the oxide should be prevented from adhering as much as possible.

In addition to the example shown in FIG. 5, the oxide removing means is
Instead of the blade, any brush such as a brush that can physically remove the oxide from the inner wall may be used. Since the inside of the furnace is at a high temperature, oxide strippers such as blades and brushes are made of heat resistant cast steel and heat resistant materials such as high alumina.

Further, cooling air 25 (compressed air is also possible) is forcibly supplied from the outside of the roasting furnace via the reduction gear train 23 and the drive shaft 24, and the rotary blade 21 on the inner wall of the roasting furnace. From the part, it is discharged into the roasting furnace to cool the rotating blade 21 and prevent thermal distortion of the rotating blade 21.

As a result, it is possible to extremely reduce the generation of iron oxide lumps adhering to the peripheral portion of the inner wall of the hot air blowing port furnace, and therefore it is possible to achieve normal maintenance of the reaction in the furnace and long-term stable operation.

[0016]

EXAMPLES The present invention will be specifically described below based on examples. (Example) Inner diameter 4.45 m, height 10 m, internal volume 140
Using a roasting furnace having a structure of m ³ shown in FIGS. 2 and 3, waste hydrochloric acid generated in the pickling step of the steel sheet was sprayed at a rate of 2,900 L / hr. The hot air blowing angle 14 was set to 16 degrees, and the hot air at a temperature of 1050 ° C. was blown at a speed of 25 at the outlet.
It blew out at 4.410 m ³ / hr at m / sec. The oxide removing means having the structure shown in FIG. 5 was used to remove the adhered oxide at intervals of 60 minutes. The results are shown in Table 1. In a conventional roasting furnace without oxide removal means, the hot air blowing direction changes from the tangential side of the inner wall of the roasting furnace to the radial side of the center of the roasting furnace due to the formation of iron oxide lumps. The average unit consumption of the fuel used for 950 × 10 ³ kcal / m ³ and concentrated waste hydrochloric acid spray liquid was also high. In the example of the present invention, the adhesion formation of iron oxide lumps was also extremely reduced, and as a result, the basic unit was stable at 850 × 10 ³ kcal / m ³ · concentrated waste hydrochloric acid spray liquid. Also, due to the decrease in the amount of fuel used, the inlet temperature of the scrubbing tower became appropriate. If this temperature is 450 ° C. or higher, the material inside the washing tower (acid-resistant / heat-resistant brick) becomes abnormal and causes equipment failure. Therefore, it is preferable to operate at 450 ° C. or lower for maintenance and maintenance. ,
This temperature problem has also been resolved. In addition, the number of continuous operation days also increased dramatically from 20 days to 184 days. As a result, the quality of iron oxide did not change with time, and it became possible to produce iron oxide of stable quality.

[0017]

EFFECTS OF THE INVENTION By using the roasting furnace of the present invention, it is possible to prevent iron oxide lumps adhering to the inner wall of the hot air blowing port from adhering to the inner wall of the furnace, and blowing the hot air into the furnace without obstructing the blowing of the hot air. By constantly and properly swirling the hot air along the inner wall of the furnace, long-term continuous operation of the equipment became possible. The quality of the iron oxide produced at the same time was also extremely stable.
For example, the amount of Cl ⁻ contained in the produced iron oxide is 0.2 w
A compression density of 2.53 ± 0.10 g / cm ³ could be stably ensured at t% or less. In addition, it has become possible to stabilize the fuel consumption rate described above at a low level.

[Brief description of drawings]

FIG. 1 is a flow chart for producing iron oxide by spray roasting.

FIG. 2 is a vertical sectional view of a roasting furnace.

FIG. 3 is a cross-sectional view of a roasting furnace.

FIG. 4 is a partially enlarged view of a hot air blowing port into a roasting furnace.

FIG. 5 is a partial vertical cross-sectional view of a roasting furnace having the deposit removing device of the present invention.

[Explanation of symbols]

 1 Waste hydrochloric acid 2 Washing tower 3 Cyclone 4 Roasting furnace 5 Top of roasting furnace 6 Spray header 7 Hot air 8 Swirling flow 9 Falling object at the center of roasting furnace 10 Falling object along the inner wall of roasting furnace 11 Tangent line 12 Inner wall of roasting furnace 13 Stagnation 14 Hot Air Blowing Angle 15 Hot Gas 16 Hot Air Blowing Means 16a Hot Air Blowing Port 17 Hot Air Discharging Port 18 Iron Oxide Recovery Port 19 Adhering Iron Oxide Block 20 Oxide Removing Means 21 Blade 22 Drive Means 23 Reduction Gear Train 24 Drive Shaft 25 Cooling air

Claims (2)

[Claims] 1. A roasting furnace main body, a spray header provided at the top of the roasting furnace main body for spraying waste hydrochloric acid generated in the pickling process of a steel sheet, and a roasting furnace provided near the bottom of the roasting furnace main body. Hot air blowing means for generating a hot air swirl flow for roasting the waste hydrochloric acid sprayed from the spray header from the vicinity of the furnace bottom toward the nip, an outlet for discharging this hot air swirl flow, and a hot air swirl flow In a roasting furnace having a recovery port for iron oxide formed by roasting and oxidation by means of hot air blowing means for removing iron oxide adhering to the periphery of the hot air blowing port opened in the body of the roasting furnace. A roasting furnace for iron oxide production, which is installed in the vicinity of the blowing port. 2. The roasting furnace for producing iron oxide according to claim 1, wherein the iron oxide removing means is a blade or a brush that is rotatable along the inner wall of the roasting furnace main body around the hot air blowing port.