JPS63111110A - Direct reduction apparatus for iron ore - Google Patents

Abstract

PURPOSE:To improve the using efficiency of soot and to facilitate the production of briquette of sponge iron by removing and recovering the soot sticking to the sponge iron after using to prevent the development of cluster in a shaft furnace by the furnace exhaust gas at the time of producing the sponge iron by reducing iron ore in the shaft furnace. CONSTITUTION:The granular iron ore 1 is charged in the shaft furnace 2 and by blowing the high temp. reducing gas generated from natural gas as raw material in a reducing gas generator 7 from a tuyere 14, the iron ore is made to the sponge iron 1a by solid reduction. In this case, by incompletely burning the natural gas in soot generator 20 to generate the soot, and the soot is blown in the furnace to prevent the development of cluster by sticking to the iron ore. As the soot is stuck to the surface of reduced sponge iron 1a, by blowing a part of the furnace exhaust gas from a nozzle 21a to the granular sponge iron 1b flowing down from the outlet 17a of the upper discharging hopper 16a, the soot is removed and recovered, for reuse in the shaft furnace. The sponge iron removing soot is sent to the briquetting machine by a container 6, to easily produce the sponge iron briquette.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to reducing soot (fine carbon particles) in reduced iron in a shaft furnace type reduction device among direct reduction devices for iron ore.
It concerns removal equipment and soot recycling.

[Conventional technology]

An overview of the shaft furnace type direct reduction apparatus to which the present invention is applied will be explained with reference to a schematic overall configuration explanatory diagram shown in FIG.

This device supplies granular or pelleted iron ore 1 to a shaft furnace (hereinafter referred to as the furnace) 2, and discharges a raw material container 3, a raw material charging bag [t4, and reduced iron 1a] to the outside of the furnace 2. A discharge device 5, a container 6 for transporting the discharged reduced iron 1a to a briquetting plant or a storage yard (none of which are shown), a reducing gas generating furnace 7 such as hydrogen (H2), and a gas compressor. It is comprised of the main components of the recycled reducing gas system 11, which includes a decarboxylation equipment 9, a decarboxylation equipment 10, a heating furnace 8, and the like.

The raw material charging device 4 has an upper hopper 12a and a lower hopper 12b attached to the top of the furnace 2, and two upper and lower seal valves 13a.

13b, the upper and lower hoppers 12a and 12b are separated by a seal valve 13a, and the lower hopper and the furnace 2 are separated by a seal valve 13b, respectively, in a gas-tight manner. It is possible to feed the raw material 1 from the container 3 into the furnace 2 according to a predetermined time schedule while keeping it airtight from the atmosphere. Inside Furnace 2.

Iron ore 1 is always retained at a predetermined level through a cutting device 15, which will be described later, and high-temperature reducing gas (H2, etc.) is supplied into the furnace from a large number of tuyeres 14 provided on the outer periphery of the lower part of the furnace body. By discharging the exhaust gas from the pipe 11a at the top of the furnace, the iron ore 1 can be reduced to reduced iron la, that is, sponge iron. The exhaust gas at the top of the furnace is sucked through the pipe 11a by the gas compressor 9, pressurized, and sent to the decarboxylation equipment 10 to the required purity, and further regenerated into high-temperature reducing gas in the heating furnace 8. An annular pipe l is connected to the pipe 11b, the regulating valve 11c and the pipe 11d.
It is circulated and supplied to the tuyere 14 via the ie. In this case, the amount of reducing gas consumed in the decarboxylation equipment 10 and the like is replenished with fresh gas from the reducing gas generating furnace 7. On the other hand, the reduced iron discharge device 5 is
A cutting device 15, such as a table feeder, attached to the bottom of the furnace 2, and an upper and lower discharge hopper 16a + 1
6t) and upper and lower double seal valves 17a, 17b.
The upper discharge hopper 16a has an integral structure with the furnace 2, and the inside of the discharge hopper 16a, that is, the inside of the furnace 2, is connected to the lower discharge hopper through the upper double seal valve 17a. Gas-tight partitioned. Lower discharge hopper 16b
is gas-tightly partitioned off from the atmosphere by a lower seal valve 17b. Also, upper and lower hoods 16a.

The 16° C. bottom portions each form an inverted conical cylinder or a square pyramidal cylinder with an appropriate inclination angle in order to smoothly discharge the reduced iron 1b by gravity. Here, the inside of the furnace 2 and the inside of the upper discharge hopper 16a are normally maintained at a predetermined pressure equal to or higher than atmospheric pressure. The soot generating furnace 20 converts natural gas NG into compressed air,
Alternatively, the cine is completely combusted with oxygen-enriched air A to generate a medium-containing reducing gas.

In the figure, 18 is an exhaust pressure valve, 19 is a medium-containing reducing gas supply pipe, and 25 is a preheating furnace.

With the above configuration, while the iron ore 1 descends in the furnace 2, it comes into contact with the reducing gas blown in from the tuyere 14 and is reduced to high-purity sponge 1a, which is sequentially passed through the cutting device 15. , is discharged to the upper discharge hole Q6a. Said Hotzet
When the sponge method 1a in 6a reaches a certain amount, the upper double seal valve 17a is opened and closed, and the lower discharge pump 16 is discharged by gravity.
It is discharged to b. In this case, the exhaust pressure valve 18 is closed. Next, when discharging the sponge 1a in the lower hopper 16b to the container 6, the upper double seal valve 17a is closed and the exhaust pressure valve 18 is opened to the atmosphere to reduce the pressure in the hopper 1!16b (
After bringing the furnace pressure (equal to the furnace internal pressure) to atmospheric pressure, it can be easily discharged by gravity by opening the lower double seal valve 171). Here, the sponge material 1a in the container 6 is granular and has a high temperature (
For example, about 5ooC), it is usually used to facilitate transportation to the next processing step, such as a steel factory or storage yard, and to prevent surface oxidation caused by the atmosphere during transportation and storage. The briquettes are transported to a briquetting plant adjacent to the furnace 2, where they are compression-molded into briquettes of a desired shape, cooled, and then transported to a storage yard or steel factory.

[Problem that the invention seeks to solve]

In conventional direct reduction equipment as described above.

It is necessary to control extremely precise operating conditions such as the properties of the reducing gas adapted to the brand of iron ore to be processed and the gas temperature in the furnace.Due to variations in these conditions, the furnace 2 Iron ore tends to combine with each other in the furnace, forming so-called clusters (C1ust, er), and these clusters gradually expand in size, resulting in the so-called hanging phenomenon in which the ore becomes blocked in the furnace. However, there is a problem in that it can lead to serious accidents such as the inability to operate.

Therefore, in the conventional apparatus described above, soot is supplied from the pipe line 19 to the annular pipe 11e, and is blown into the furnace 2 from the tuyere 14 together with the reducing gas (H2 etc.), so that the iron ore 1 in the furnace and the reduced The generation of υ clusters is prevented by adhering soot to the surface of the iron 1a. However, when soot is blown into the furnace 2 in this way, the sponge method 1a is discharged into the container 6.
The soot adheres to the surface of the briquette, and if compression molding is performed as it is, for example, in a roll-type briquette machine, the adhering soot will prevent the compression of the sponge method 1a, and the briquettes will not be formed into a predetermined shape. A big problem arises that it cannot be done.

Also, since the sponge iron is sent to the briquetting machine with soot attached to its surface, the soot (suit) cannot be recycled, and therefore it must be produced in a soot generating furnace. Therefore, a large amount of natural gas is required as a raw material.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention has been proposed (a) to prevent the flow of reduced iron from the surroundings from flowing into the upper part of the lower discharge hopper of the reduced iron discharge device along the flow path of the reduced iron falling into the hopper; An annular blowing rod with a nozzle capable of continuous spraying is installed. (b) A pipe line is provided to bypass a portion of the recycled reducing gas supplied into the shaft furnace and introduce it into the blow hood. (c) The upper part of the lower reduced iron discharge hopper is communicated with the recycled reducing gas supply pipe leading to the shaft furnace.

[Effect]

Recycling gas is blown into the flow of reduced iron falling into the discharge hopper to remove soot adhering to the surface of the reduced iron. The soot removed from the surface of the reduced iron in the discharge funnel passes through the recycle gas bypass pipe in the upper part of the hopper and is again supplied into the shaft furnace.

〔Example〕

A detailed explanation will be given below with reference to the drawings.

FIG. 1 is a schematic overall configuration explanatory diagram of the shaft furnace type surface reduction apparatus of the present invention. The same or similar members as those of the conventional apparatus (FIG. 2) described above are given the same reference numerals, and overlapping explanations of the configuration are omitted. Omitted.

In the apparatus of the present invention, as shown in the figure, in the lower discharge hopper 16b of the reduced iron discharge device 5, an upper discharge horn /' 16
A substantially annular blowing tool (21) having a plurality of gas nozzles 21a arranged vertically and at substantially equal pitches in the circumferential direction along the periphery of the inlet passage 1b for reduced iron that is charged by gravity from a. Install.

These nozzles 21a are connected to a pipe line 11b between the outlet of the heating furnace 8 and the regulating valve 11c via a pipe line 24a and a regulating valve 24b, and the reduced iron 1a falling from the gas nozzle 21a is
Recycled reducing gas is blown from around the reduced iron 1a to separate and scatter soot attached to or mixed in the reduced iron 1a.

On the other hand, an exhaust gas pipe 24e is installed at an appropriate position on the top of the discharge hopper 16b, and a mixed gas of recycle gas and soot blown from the gas nozzle 21a is passed through the valve 24c and the pipe 24e.
d, the pipe line 11d between the regulating valve 11c and the annular pipe lie
°Introduce to. Pipe line 24a, blow hood 21, gas nozzle 21a, lower discharge hopper 16b, exhaust gas pipe line 24e,
The pipe line 24d constitutes a bypass pipe line for the recycled reducing gas. Note that the inner dimensions of the blowing hood 21 are as follows:
The inner surface of the reduced iron 1a is placed close to the falling reduced iron 1a without coming into contact with it, and its height is determined by providing an appropriate space between the top of the reduced iron 1a staying in the hopper 16b and the top of the hopper, so that the reduced iron 1a does not come into contact with the falling iron 1a. Due to the injected gas, reduced iron 1
It is set so that the soot adhering to and mixed in the air can be efficiently separated and scattered, and it can be easily sucked and discharged together with the gas into the exhaust gas pipe 24e.

Next, the operation of the apparatus of the present invention having the above configuration will be described. In addition, FIG. 1 shows reduced iron 1a into the lower discharge hopper 16b.
Indicates that the gas is being discharged, and the recycled reducing gas is being circulated.

First, prior to discharging the reduced iron 1a from the upper discharge hopper 16a to the lower hopper 16b, the valve 24b.

24c is opened to blow the gas into the blow hood 21 and recycled, and then the upper double seal valve 17a is opened. Thus, while the reduced iron 1a falling by gravity into the lower hopper 16b passes through the blowing hood 21, the soot attached or mixed therein is separated and scattered by the gas, and the reduced iron 1a passes through the pipes 24e and 24a together with the gas.
+lid, and is blown into the furnace 2 again. In this case, the pipe 24d passes from the pipe 24a through the blowing foot "21".
The gas flow rate and pressure balance between the silicycle gas system pipe line 11d and the bypass pipe line 24d are appropriately controlled by the regulating valve 24b according to the ventilation resistance reached.

After the discharge of the reduced iron 1a to the hopper 16b is completed, the upper double seal valve 17a is closed, and after the soot in the hopper 16b is completely removed, the valves 24b and 24c are closed in preparation for the next discharge operation. Following the procedure of the conventional apparatus (FIG. 2), the reduced iron 1a is discharged into the container 6, transported to a briquenting plant, and formed into briquettes.

In the device illustrated above, the gas blowing nozzle in the lower discharge hopper 16b is a substantially annular blowing nozzle, but the nozzle type is not limited to this. Of course, any structure may be used as long as it does not obstruct the flow of the reduced iron 1a and allows gas to pass through while the reduced iron is falling.

〔Effect of the invention〕

When the reduced iron in f is discharged from the upper discharge hopper to the lower discharge hopper, the reduced iron falling by gravity into the lower hopper is passed from the annular blower 7 to 9 installed around the flow path of the reduced iron. By spraying recycled reducing gas to separate and scatter the soot adhering to and mixing with the reduced iron 1a, the reduced iron discharged into the container is free from adhering to or mixing with carbon soot, unlike conventional equipment. As a result, in the subsequent briquetting machine, it is possible to form the zuricherato into a desired shape extremely easily and stably, and production efficiency can be improved.

In addition, the soot that has been separated from the reduced iron in the discharge hopper is blown into the shaft furnace again, so compared to conventional equipment,
It becomes possible to significantly reduce the consumption of raw materials for soot production.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the overall configuration of a shaft furnace type direct reduction apparatus according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram of the overall configuration of a conventional shaft furnace type direct reduction apparatus. 1...Iron ore raw material 1a...Reduced iron 1b...
-Reduced iron flow path 2...Shaft furnace...Reduced iron discharge device 16a, 16b...Discharge hopper ξ20.
...Soot generating furnace 21...Blowing hood 21a.
...Gas nozzle sub-agent Patent attorney Shigefumi Okamoto (2 others)

Claims (1)

[Claims] Direct reduction of iron ore, in which granular or pelleted iron ore is reduced to reduced iron by supplying reducing gas added with fine carbon (suit) into the shaft furnace, and the reduced iron is discharged outside the furnace in a high temperature state. In the apparatus, an annular blowing hood equipped with a gas nozzle is installed around the flow path of the reduced iron flowing into the discharge hopper, and a part of the recycled reducing gas supplied to the shaft furnace is bypassed to the blowing hood. introduced,
Furthermore, the iron ore direct reduction apparatus is characterized in that the upper part of the discharge hopper is connected to a recycled reducing gas supply pipe leading to the shaft furnace.