JPH11172309A - Smelting reduction apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a smelting reduction apparatus, in which good fluidizing condition in a fluid is stably formed, a prescribed reduction capacity is obtd., the increase in dust loss is prevented and the control of supplying quantity into the smelting reduction furnace is easily executed and further, even at the time of shutting down of the smelting reduction furnace, the restarting is easily executed. SOLUTION: In the smelting reduction apparatus provided with a prereduction furnace 20 having a wind box 23 formed at the lower part and having a fluidized bad 22 formed at the upper part across a dispersion plate 21, the smelting reduction furnace 10 charged with the pre-reduced ore in the fluidized bed of the pre-reduction furnace and an exhaust gas duct 30 connected to the wind box in the pre-reduction furnace from the top part of the smelting reduction furnace, dropped one system piping 37 is connected to the interval between the bottom part of the wind box and the upper part of the smelting reduction furnace and in this piping, a feeding means 38 for feeding the dropped ore in the wind box 23 through the dispersion plate 21 from the fluidized bed 22 into the smelting reduction furnace 10, is attached.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a smelting reduction apparatus having an improved ore dropping path.

[0002]

2. Description of the Related Art As a prior art, Japanese Patent Laid-Open Publication No.
There is an official gazette. In this technique, as shown in FIG. 2, the bottom of the wind box 1a of the preliminary reduction furnace 1 and the top of the
The ore is supplied from the preliminary reduction furnace 1 to the smelting reduction furnace 2 by dropping the ore from the preliminary reduction furnace dispersion plate 1a. The amount of ore fall is adjusted by adjusting the opening of the exhaust gas damper 5 attached to the exhaust gas pipe 4 attached to the upper part of the preliminary reduction furnace. That is, when the opening degree of the damper is increased, the pressure in the preliminary reduction furnace decreases, the gas flow velocity in the dispersion plate nozzle increases, and the amount of ore drop decreases. Conversely, when the damper opening is reduced, the pressure in the preliminary reduction furnace increases, the gas flow velocity in the dispersion plate nozzle decreases, and the amount of ore drop increases.

[0003] However, there is a problem that the gas flow rate in the pre-reduction fluidized bed also changes if the amount of ore drop is controlled by adjusting the gas flow rate in the nozzle. Generally, there is an appropriate range of gas flow rate in the bed to realize stable ore fluidization of ore in the preliminary reduction furnace, but the gas flow rate in the nozzle is changed to control the amount of ore drop as described above. Then, the gas flow velocity in the layer also changes. For this reason, it is difficult to stably form a favorable fluidized state in the fluidized bed with the conventional technology.

[0004] For example, when the gas flow velocity in the fluidized bed exceeds a proper range, most of the fine ore is discharged from the freeboard to the outside of the furnace, and the fluidized bed is not formed. as a result,
The predetermined reduction performance cannot be obtained. Further, ore liquefaction is promoted, and so-called dust loss that passes through a dust collecting device such as a cyclone increases.

Conversely, when the gas flow rate in the fluidized bed is out of the proper range and becomes small, the fluidization of the ore becomes inactive, an immobile area of the ore is generated, and the ore sticks in the furnace. As a result, predetermined reduction performance cannot be obtained.

Further, in this method, since the amount of ore supplied to the smelting reduction furnace is adjusted by the damper opening, it is difficult to control the amount of ore supplied to the smelting reduction furnace in terms of responsiveness and accuracy. Furthermore, at the time of shutting down the smelting reduction furnace, since all the ore retained in the layer in the preliminary reduction furnace is dropped and supplied to the smelting reduction furnace, the temperature of the molten iron in the smelting reduction furnace decreases, and in extreme cases,
The molten iron solidifies in the furnace, which makes it difficult to restart.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to stably form a good fluidization state in a flow and obtain a predetermined reduction performance. Thus, it is possible to provide a smelting reduction apparatus that can prevent an increase in dust loss, can easily control the supply amount to the smelting reduction furnace, and can easily restart when the smelting reduction furnace is shut down.

[0008]

That is, the present invention provides (1)
A pre-reduction furnace with a wind box at the bottom and a fluidized bed at the top via a dispersion plate, a smelting reduction furnace into which the ore pre-reduced in the fluidized bed of the pre-reduction furnace is charged, and an upper part of the smelting reduction furnace In the smelting reduction apparatus having an exhaust gas duct connected to the inside of the wind box of the preliminary reduction furnace, a fallen pipe is connected between the bottom of the wind box and the top of the smelting reduction furnace. A smelting reduction device equipped with a cutting means for cutting ore dropped from the fluidized bed into a wind box through a dispersion plate into a smelting reduction furnace; (2) the wind box is provided with an exhaust gas duct; The smelting reduction device according to (1), wherein the volume below the position is equal to or more than the volume of ore retained in the fluidized bed, (3) the wind box is at the bottom, when the operation of the smelting reduction furnace is stopped. It is specially connected to a fallen pipe discharge system that discharges ore retained in the wind box to the outside of the system. A smelting reduction apparatus according to (1) or (2) and.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a smelting reduction apparatus according to the present invention will be described below with reference to FIG. This apparatus includes a smelting reduction furnace 10 and a preliminary reduction furnace 20. The smelting reduction furnace is charged with an oxygen lance 11 from the top toward the inside,
A metal layer 12 and a slag layer 13 are formed in the furnace by smelting reduction. The pre-reduction furnace has a fluidized bed 22 formed at an upper portion thereof and a wind box 23 formed at a lower portion thereof via a dispersion plate 21. Further, an exhaust gas duct 30 is connected between the wind box side of the preliminary reduction furnace and the top of the smelting reduction furnace, so that the exhaust gas generated in the smelting reduction furnace is introduced into the wind box and blown into the fluidized bed through the dispersion plate. Has become. In the wind box, the volume of the wind box below the mounting position of the exhaust gas duct is desirably equal to or more than the amount of ore retained in the fluidized bed. A raw ore charging pipe 31 is attached to the upper part of the preliminary reduction furnace, and a cyclone 32 is attached to the upper part. A fine particle pipe 33 is connected to the bottom of the cyclone and the top of the smelting reduction furnace, and a cutout device 34 is attached to the fine particle pipe. A coarse-grained piping 35 is connected from the position of the fluidized bed of the preliminary reduction furnace to the upper part of the smelting reduction furnace, and a cutout device 36 is mounted here. Next, an ore dropping pipe 37 is connected between the bottom of the wind box and the upper part of the smelting reduction furnace, and a cutout device 38 is mounted here. Further, a pipe 39 outside the dropping system is installed at the bottom of the wind box.
Is connected, and a non-mineralized discharge system on-off valve 42 is mounted here. An exhaust gas flow meter 40 is provided in the exhaust gas duct 30.
Is attached, a shutdown of the smelting reduction furnace is detected by a flow rate detection signal of the flow meter, and the downfall opening / closing valve 41 is closed by the shutdown detection signal.
The off-mineral discharge system open / close valve 42 is opened.

As described above, this apparatus is provided with three systems of ore supply from the pre-reduction furnace to the smelting reduction furnace: coarse-grain system, fine-grain system, and ore drop system. The supply of the coarse-grained system and the fine-grained system is quantitatively performed by the respective cutting devices 34 and 36.
In the falling ore system, the ore that has fallen into the wind box is quantitatively cut out by the cutting device 38 by the amount of ore fall.

The ore supply to the smelting reduction furnace can be performed with high precision and high responsiveness by quantitatively cutting out ore droppings. Further, since the gas flow rate in the bed is not changed, a good fluidized state in the fluidized bed can be stably realized.

Next, when the smelting reduction furnace is shut down, the ore dropping on-off valve 41 is closed, and the ore accumulated in the formation is entirely deposited in the wind box below the duct. Therefore, it is possible to prevent ore from flowing into the smelting reduction furnace at the time of shutdown, and also to prevent the exhaust gas duct 30 from being clogged by falling ore, thereby enabling stable operation of the smelting reduction furnace.

Further, in conjunction with the shutdown of the smelting reduction furnace, the off-mineralized discharge system on-off valve 42 is opened, and the ore-mineralized ore is temporarily discharged outside the system. As a result, the size of the wind box 23 is reduced, and the size of the preliminary reduction furnace can be reduced.

[0014]

[Example] In the apparatus shown in FIG. 1, production volume: 3000 t / d, fluidized bed furnace diameter: 7.2 m, fluidized bed furnace height: 7 m above the dispersion plate, ore retention in the furnace: 56 t, wind box volume (under the duct): The pre-reduction furnace is composed of 120 m ³ , and the ore is dropped at a predetermined ratio (for example, 2%) with respect to the amount of ore supplied to the pre-reduction furnace. Set. The timing of ore dropping was started at the start of ore supply to the pre-reduction furnace, and ended when the amount of ore stagnant in the pre-reduction furnace was exhausted.

Thus, as a result of operating under the above operating conditions, it was confirmed that a favorable fluidization state in the flow was formed stably, and a predetermined reducing performance was obtained. Furthermore, it was confirmed that an increase in dust loss was prevented, the supply amount to the smelting reduction furnace was easily controlled, and further, the smelting reduction furnace was easily restarted when shutting down.

[0016]

As described above, according to the present invention, since the gas flow rate in the nozzle is not adjusted for controlling the amount of ore dropping, a good fluidized state in the fluidized bed is stably formed. be able to. As a result, a predetermined reduction performance can be obtained, and an increase in dust loss can be prevented. Further, since the supply control of the ore dropping amount can be directly performed, the responsiveness and accuracy thereof can be improved. Furthermore, when shutting down the smelting reduction furnace, the ore drop is discharged outside the system,
It has a remarkable effect such as easy restart.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a smelting reduction furnace of the present invention.

FIG. 2 is a schematic explanatory view of a smelting reduction furnace described in JP-A-4-63216.

[Explanation of symbols]

10 ... Smelting reduction furnace, 11 ... Oxygen lance, 12 ... Metal layer, 13 ... Slag layer, 11 ... Pre-reduction furnace, 21 ... Dispersion plate, 22 ... Fluidized bed , 23 ... wind box, 30 ... exhaust gas duct,
31 ... Raw material ore charging pipe, 32 ... cyclone, 33 ... fine-grained piping, 34 ... dispensing device, 35 ... coarse-grained piping, 36 ...
Cutting device, 37 ... Plumbing pipe, 38 ... Cutting device, 3
9 ... Exhaust pipes outside the dropping system, 40 ...
Dropping-type on-off valve, 42 ...

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeshi Sekiguchi 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Masayuki Watanabe 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Sun (72) Inventor Katsuhiro Iwasaki 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd.

Claims (3)

[Claims] 1. A pre-reduction furnace having a wind box at the lower part and a fluidized bed formed at the upper part via a dispersion plate, a smelting reduction furnace into which the ore pre-reduced by the fluidized bed of the pre-reduction furnace is charged. In a smelting reduction apparatus comprising an exhaust gas duct connected from the upper part of the smelting reduction furnace to the wind box of the preliminary reduction furnace, a fallen pipe is connected between the bottom part of the wind box and the upper part of the smelting reduction furnace. A smelting reduction apparatus, characterized in that a cut-out means for cutting ore dropped from a fluidized bed through a dispersion plate into a wind box into a smelting reduction furnace is attached to the conduit. 2. The smelting reduction apparatus according to claim 1, wherein a volume of the wind box below a mounting position of an exhaust gas duct is equal to or more than a volume of ore retained in a fluidized bed. 3. A discharge system outside the ore dropping system for discharging ore retained in the wind box outside the system when the operation of the smelting reduction furnace is stopped is connected to the bottom of the wind box. 3. The smelting reduction device according to 2.