JPH09157719A - Smelting reduction apparatus of iron - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the operation of a smelting reduction furnace even at the abnormality in the operation of a pre-reduction furnace or the smelting reduction furnace, e.g. temporary increase of an iron ore in the pre-reduction furnace or abrupt decrease of generated gas in the smelting reduction furnace. SOLUTION: A smelting reduction apparatus is constituted with the smelting reduction furnace 11, the fluidized bed type pre-reduction furnace 1, in which the generated gas of the smelting reduction furnace as the gas for reduction is introduced from a wind box at the lower part and brought into contact with the iron ore on a dispersing plate and discharged from a discharging tube at the upper part, piping for introducing the generating gas by connecting the furnace top opening of the smelting reduction furnace 11 with the sidewall part of the wind box, a pre-reduced ore charging pipe 16 for discharging the pre-reduced iron ore into the furnace top opening of the smelting reduction furnace 11 from the lower part of the fluidized bed and a recovering device 10 for separately collecting dust of the generated gas and dropped ore from the dispersing plate through the discharging hole at the bottom part of the wind box 3. By this constitution, since the dust contained in the generated gas and the dropped ore of the pre-reduction furnace 1 is not directly dropped into the smelting reduction furnace 11 but separately recovered into the recovering device 10, the operation of the smelting reduction furnace 11 is not disturbed and the dropped ore and dust can accurately be grasped and the stable operation can be obtd.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an iron smelting reduction apparatus.

[0002]

2. Description of the Related Art In the smelting reduction method of iron ore, raw materials such as iron ore, coal, and auxiliary raw materials having a fine grain size can be directly charged into a smelting reduction apparatus, so that a sinter plant and a coke plant are not required, and blast furnace steelmaking This is an excellent steelmaking method that is more economical than the law and can solve the environmental problems that have occurred at both plants.

The smelting reduction method of iron ore is a method of obtaining pig iron by reducing iron ore in a molten state using a smelting reduction furnace.
While the smelting reduction furnace has a quick reaction and can adjust the productivity elastically, it has a low energy utilization rate, so that a smelting reduction apparatus is often constructed with a preliminary reduction furnace.

In the preliminary reduction furnace, C generated in the smelting reduction furnace is used.
A high temperature gas containing O as a main component is introduced as a reducing gas. The iron ore in the pre-reduction furnace is pre-reduced and pre-heated in the solid state, and charged into the smelting reduction furnace. As a preliminary reduction furnace, a fluidized bed type that is suitable for the reduction of granular or powdery iron ore is generally adopted.The conventional smelting reduction apparatus is an iron bath type smelting reduction furnace and a fluidized bed type. It consists of a preliminary reduction furnace of
During operation, high-temperature reducing gas is generated from the smelting reduction furnace,
The high-temperature reducing gas is introduced from the upper part of the smelting reduction furnace to the lower part of the pre-reduction furnace through a pipe, and the pre-reduction furnace preheats and pre-reduces the iron ore.

As an example of these conventional smelting reduction apparatuses, the apparatus disclosed in Japanese Patent Laid-Open No. 4-63216 is shown in FIG. In this apparatus, the pre-reduction furnace 1 and the smelting reduction furnace 11 are directly connected by a pipe line 21, and the pipe line 21 connects the reducing gas passage from the smelting reduction furnace 11 to the pre-reduction furnace 1 and melts it from the pre-reduction furnace 1. It is a smelting reduction apparatus that also serves as a passage for ore that has been preheated / preliminarily reduced to the reduction furnace 11, and does not have a dust recovery device in the middle of the pipeline 21. It can be effectively used in the preliminary reduction furnace 1 without lowering it.

In this smelting reduction apparatus, the iron ore charged into the fluidized bed chamber 4 of the preliminary reduction furnace 1 through the iron ore charging pipe is preheated and preliminarily reduced on the dispersion plate 2. During operation, falling slag is generated from the dispersion plate 2.
Because the structure is such that it does not stay in the smelting furnace and immediately falls into the smelting reduction furnace 11 through the pipe line 21, the falling ore does not accumulate in the wind box 3 for a long time, and the falling ore does not stick in the wind box. .

[0007]

However, in the smelting reduction apparatus disclosed in Japanese Patent Laid-Open No. 4-63216,
Although the loss of sensible heat of exhaust gas is small, if the falling mine increases due to operating conditions, the operation of the smelting reduction furnace may be adversely affected as follows.

In this smelting reduction apparatus, a damper 27 is provided on the downstream side of the preliminary reduction furnace, that is, after the exhaust gas pipe 6, the opening degree of the damper 27 is adjusted, and the smelting reduction furnace 11 passing through the dispersion plate 2 is generated. The gas flow rate is adjusted. The amount of preheated / pre-reduced iron ore charged into the smelting reduction furnace 11 is adjusted by adjusting the flow rate of the generated gas in the dispersion plate 2.
Therefore, when the amount of iron ore put on the dispersion plate 2 is temporarily increased, or when the smelting reduction furnace 11 is in operation, the amount of oxygen fed is reduced or stopped. When the flow velocity of the gas passing through the dispersion plate 2 is rapidly reduced, the situation in which the ore charging amount increases in a short time, so-called falling mine occurs.

It is extremely difficult to control the amount of ore charged in the preliminary reduction furnace 1 in such an emergency, and when iron ore falling occurs due to insufficient preheating and preliminary reduction, or in the smelting reduction furnace. When the hot metal temperature of No. 11 is low, the hot metal temperature further decreases due to falling rock, and the furnace condition deteriorates. In the worst case, the operation of the smelting reduction furnace 11 may become impossible due to insufficient heat.

Further, since this smelting reduction apparatus does not have a separating device for the dust generated from the smelting reduction furnace, the amount of dust lost with respect to the amount of raw material (particularly carbonaceous material) charged into the smelting reduction furnace 11 is grasped. Since it is not possible to know the remaining amount of the input components in the furnace, which is one of the important guidelines during operation, it is necessary to always take prompt operation action because the inside of the smelting reduction furnace is under highly reactive conditions. However, the smelting reaction state in the smelting reduction furnace cannot be grasped at all.

Furthermore, since the iron ore charged to the smelting reduction furnace contacts the generated dust while the iron ore is fluidized on the dispersion plate of the preliminary reduction furnace, the generated dust on the surface of the charged iron ore. Sometimes adhered to the iron ore and prevented the contact between the iron ore and the reducing gas, and the preheating / pre-reduction of the iron ore was delayed and became insufficient.

The present invention has been made in order to solve such a problem, and the sensible heat of the gas generated from the smelting reduction furnace can be effectively used in the preliminary reduction furnace, and the slag produced during operation It is intended to provide a smelting reduction apparatus capable of eliminating adverse effects and sufficiently grasping the amount and properties of falling mine and dust.

[0013]

In the iron smelting reduction apparatus of the present invention, a smelting reduction furnace and its generated gas are introduced as a reducing gas from a lower wind box and brought into contact with iron ore on a dispersion plate. Later, a fluidized bed type pre-reduction furnace that discharges from the upper exhaust gas pipe, a pipeline that connects the smelting reduction furnace and the side wall of the wind box of the pre-reduction furnace, and introduces the generated gas, and the iron ore that is pre-reduced from the lower part of the fluidized bed It consists of a discharge pipe for preliminary reduced ore discharged to the furnace mouth of the smelting reduction furnace, and a recovery device for collecting and separately collecting dust of generated gas and falling ore from the dispersion plate through the discharge hole at the bottom of the wind box. Is a smelting reduction apparatus for iron ore.

Since the smelting reduction furnace and the air box of the preliminary reduction furnace are directly connected by the pipe line, the sensible heat of the gas generated from the smelting reduction furnace can be effectively used in the preliminary reduction furnace. Further, the dust held by the generated gas in the wind box and the falling ore from the dispersion plate of the preliminary reduction furnace are collected, and the discharge hole for discharging the dust and the falling ore and the dust discharged from the discharge hole. Since a recovery device is installed to recover the iron ore and the iron ore, the iron ore put on the dispersion plate temporarily increases, or the smelting reduction is performed by stopping or stopping the acid transfer during the operation of the smelting reduction furnace. Even if the amount of gas generated from the furnace sharply decreases and the gas flow velocity at the dispersion plate nozzle sharply decreases, the pipe for introducing the generated gas opens at the side wall of the wind box, so iron ore It can be recovered by a recovery device without falling directly to the smelting reduction furnace.

Therefore, the operation of the smelting reduction furnace is not disturbed, and the amount of falling ore and dust generated can be accurately grasped, so that stable operation can be performed.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic sectional view of a smelting reduction apparatus according to the present invention.

The preliminary reduction furnace 1 is composed of a dispersion plate 2, a wind box 3, a fluidized bed chamber 4 and an exhaust gas pipe 6, and an iron ore charging pipe 5 is arranged in the fluidized bed chamber 4. Preheating in fluidized bed chamber 4
The pre-reduced iron ore is discharged from the pre-reduced ore discharge pipe 7. Preliminary reduction ore discharge pipe 7 of this preliminary reduction furnace 1
Is connected by a pipe to a preheating / pre-reduction iron ore charging pipe 16 of the smelting reduction furnace 11. At the bottom of the wind box 3,
A discharge hole 8 for discharging falling rocks and dust is arranged. A discharge pipe 9 is connected to the discharge hole 8, and the discharge pipe 9 is further connected to a recovery device 10. Recovery device 10
Is a rock fall recovery tank 10a that mainly collects rock fall, and a dust recovery tank 10b that mainly collects dust in the generated gas.
It is composed of In the discharge pipe 9, at least one or more adhering prevention purge pipes 22 and adhering detectors 23 are installed.

The smelting reduction furnace 11 is composed of a furnace body 12 and a hood 13. An iron bath 14 is stored in the bottom of the furnace body 12, and the furnace body 12 is supported by a furnace body supporting device 15, and the iron bath 14 is
A gas blowing pipe 19 for stirring the gas is connected. Connected to the hood 13 are a reduced iron ore charging pipe 16, a coal and auxiliary raw material charging pipe 17, an oxygen blowing lance 18, a dust blowing pipe 20, and a pipeline 21.

The furnace body 12 includes a hood 13 and a conduit 21.
Is connected to the side wall of the wind box 3 of the preliminary reduction furnace 1.

Since dust in the generated gas passes through the pipe 21, the purge pipe 22 for preventing adhesion is attached to a portion such as the lower surface of the horizontal portion or the bent portion in the pipe 21 where dust is likely to accumulate. The detectors 23 are installed in at least one place. A pressure gauge or a thermometer is used as the adhesion detector 23.

The dust in the generated gas that passes without adhering to the pipe 21 has a large decrease in the flow velocity of the generated gas as soon as it enters the wind box 3 of the preliminary reduction furnace 1, so most of the dust is in the wind box. It is naturally dropped in the direction of the discharge pipe 9 in the lower part of the inside 3 and collected. In addition, for example, a weir 24 is provided at the joint between the pipe 21 and the wind box 3 of the preliminary reduction furnace 1, or the pipe 2 at the joint is formed.
The flow of the generated gas may be forcibly changed by making the inner diameter of 1 smaller or larger than that of the other portion to make it easier to collect dust.

The dust collected in the lower part of the wind box 3 of the preliminary reduction furnace 1 is discharged to the outside of the wind box 3 through the discharge pipe 9. In FIG. 1, the number of discharge pipes 9 from the wind box 3 is one, and the falling mine and the dust can be discharged from the same discharge pipe 9 to make the apparatus compact.

During normal operation, since the flow velocity of the gas generated in the dispersion plate 2 is sufficiently secured, there is almost no falling mine from the dispersion plate 2, so the valve 25 on the falling mine recovery tank 10a is set. Close and open the valve 26 on the dust recovery tank 10b to collect the dust collected in the wind box 3 through the discharge pipe 9 toward the dust recovery tank 10b. The amount of dust collected in the dust collection tank 10b and the component value are measured, and then the dust is introduced into the smelting reduction furnace 11 through the dust blowing pipe 20.

When an abnormality occurs in the smelting reduction furnace 11, or when the operation of the smelting reduction furnace 11 is started or stopped, a large amount of mine ore is generated, so valve 25 is opened and valve 26 is opened. By closing, a mixture of fallen rock and dust is collected in the fallen rock collection tank 10a. Then, until the operation status of the smelting reduction furnace 11 is recovered or stabilized, the operation of the smelting reduction furnace 11 is maintained by discharging the dust to the outside of the system without introducing the dust into the smelting reduction furnace 11. When the operation of the smelting reduction furnace 11 is restored or stabilized, the dust recovery is resumed in the dust recovery tank 10b.

[0025]

According to the present invention, the sensible heat of the gas generated from the smelting reduction furnace can be effectively utilized in the preliminary reduction furnace, and the generation amount of dust and falling mine and the remaining amount in the furnace can be accurately grasped. Even when the start-up or stop of the operation due to fluctuations in the operating conditions, the adverse effect on the smelting reduction furnace can be completely eliminated by using the recovery device, and stable operation can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a smelting reduction apparatus of the present invention.

FIG. 2 is a schematic sectional view of a conventional smelting reduction apparatus.

[Explanation of symbols]

 1 Pre-reduction furnace 2 Dispersion plate 3 Air box 4 Fluidized bed chamber 5 Iron ore input pipe 6 Exhaust gas pipe 7 Pre-reduction ore discharge pipe 8 Discharge hole 9 Discharge pipe 10 Recovery device 11 Melt reduction furnace 12 Furnace body 13 Fu- Do 14 Iron bath (molten iron) 21 Pipeline

Claims (1)

[Claims] 1. A smelting reduction furnace and a fluidized bed type pre-reduction furnace in which the generated gas is introduced as a reducing gas from a lower wind box to contact with iron ore on a dispersion plate and then discharged from an upper exhaust gas pipe. And a pipe line that connects the smelting reduction furnace and the side wall of the wind box of the preliminary reduction furnace to introduce the generated gas, and discharges the pre-reduced iron ore from the lower part of the fluidized bed to the throat of the smelting reduction furnace. An iron ore smelting reduction apparatus comprising a pipe and a recovery device for collecting and separately collecting dust of generated gas and falling ore from a dispersion plate through a discharge hole at the bottom of a wind box.