JPS5896805A - Production of pig iron - Google Patents

Abstract

PURPOSE:To produce pig iron with high thermal efficiency by the use of fine ore as a raw material and low strength coke by combining a melting and gasifying furnace which permits gasification of coal, etc. and melting of reduced iron and a rotary kiln type ore reducing furnace. CONSTITUTION:In a melting and gasifying furnace wherein tuyeres 5 for blowing of oxygen, steam 11, pulverized coal 12, a charging port 6 for coal, limestone, etc. 13 are provided in the side wall parts and a charging port 7 for reduced iron 4 and coke 14, and a gas discharge port 8 are provided in the upper part and a tap and slag hole 9 is provided in the lower part, the calory of the combustion gases generated in a fuel chamber (a) is increased by the coke packed in a heating part (b), and said combustion gas melts the reduced iron 4 in a melting part (c). The molten reduced iron 4 flows down while receiving carburization and reduction of SiO2 in a heating part (b) and arrives at a well (d). On the other hand, in a rotary kiln type reducing furnace 2 provided with a feed port 15 for fine ore, coal and limestone, a blow port 17 for a reducing gas 3 and air, a delivery port 16 for reduced iron, etc., the fine ore is reduced and is supplied to the furnace 1.

Description

Detailed Description of the Invention This invention combines a melting gasification furnace that enables gasification of coal and melting of reduced iron, and a rotary kiln-type ore reduction furnace to achieve high production comparable to the high-Q method. The present invention relates to a method for producing pig iron that achieves high heat resistance and thermal efficiency, and also allows the use of fine ore.

There are two methods for reducing and melting iron ore to produce pig iron: one is to reduce the iron ore in lump form to a gas and then melt it, and the other is to melt the iron ore by heating and then reduce it with a solid reducing agent. It is well known that the blast furnace method belongs to the latter category, and the smelting reduction method belongs to the latter category.

However, the solid reduction of molten ore in the smelting reduction method is a significantly endothermic reaction, and it is extremely difficult to stably supply heat to a reaction bath, and the refractory is severely eroded by the molten ore.

At present, there are virtually no processes that have productivity rates comparable to those of the blast furnace process.

On the other hand, in a method such as the blast furnace method in which iron ore is gas-reduced and then melted, the gas reduction of iron ore is a slightly exothermic reaction, so the reduction reaction proceeds stably, and the iron oxides in the fg melt are There are fewer problems with damage to refractories than with the smelting reduction method. In addition, the blast furnace method has an extremely high thermal efficiency since the ore is gas-reduced and dissolved within the same chamber, and has the advantage that energy consumption can be reduced by recovering the resulting gas and using it for other purposes.

However, as is well known, in the blast furnace method, it is essential to ensure good air permeability in the furnace and stable descent of the loaded materials, so the coke used must be of high strength or high quality with low reactivity. However, its production requires high-quality coking coal and carbonization energy, and the agglomerate ore used must have high strength and excellent softening properties. Therefore 1w.

In the future, where the restaurant industry is expected to deteriorate, the development of an ironmaking method like the blast furnace method, which can combine productivity and high heating rate, and also allows the use of low-quality raw materials, will be of great significance. Much research and development has been carried out so far.

Under these circumstances, the inventors proposed a method for melting reduced iron and producing reducing gas as a method that reduces energy consumption, reduces coke ratio, and uses low-grade raw materials compared to the blast furnace method. He first proposed a method for manufacturing pig iron by combining a melting gasification furnace and an illll stratified reduction furnace.
This is a method in which the gas produced in the melting and gasifying furnace is used as the reducing gas in the dream bed reduction furnace and is recovered, and the reduced iron produced in the reducing furnace is melted in the melting and gasifying furnace.

However, since this method was invented in consideration of preventing troubles such as ventilation obstruction in the FG decomposition and gasification furnace, the iron raw materials are mainly lump ores and agglomerates (cold bond wire, sintered ore, etc.). The only difference is that it uses powdered ore.

Therefore, from the viewpoint that there is a high possibility that iron raw materials will shift to mainly powder in the future, the inventors developed a method for producing pig iron mainly using powdered ore, based on the same principle as the pig iron making method described above. .

Hereinafter, this invention will be explained in detail.

This invention relates to a method for manufacturing pig iron by combining a melting and gasifying furnace for melting reduced iron and producing reducing gas with an ore reduction furnace. This is a method in which a reduction furnace is used to reduce and mold fine ore, which is then charged into a molten gas furnace, and the gas produced in the molten gas furnace is used as fuel gas for the rotary kiln type reduction furnace.

That is, the gist of this invention is to provide oxygen to the side wall of the furnace body.

It has a lining for steam and pulverized coal injection, a coke, coal, limestone charging inlet above the tuyere, reduced iron, coke charging inlet and gas outlet in the upper part of the furnace body, and a tap slag port in the lower part of the furnace body. A combustion chamber consisting of a packed bed of coke, coal, limestone, etc., which is charged from the charging port above the tuyere, is formed in front of the tuyere. forming a heating section consisting of a packed bed of coke charged from
A melting section consisting of a packed bed of reduced iron charged from the upper part of the furnace body is formed above this heating section, and in the combustion chamber, coke and coal and pulverized coal, etc., are injected from the tuyere at the same time. The combustion gas is gasified with oxygen and water vapor to produce high-temperature combustion gas mainly composed of carbon oxide and hydrogen, and molten slag produced by thermal decomposition of coke, coal ash, and limestone. After passing through the front heating section and melting reduced iron in the melting section consisting of a reduced iron packed bed above the heating section, the reduced iron is recovered from the gas outlet, and the molten slag is generated in the melting section and consists of a coke packed bed. The melting and gasifying furnace is designed so that the heating section is dripped with molten reduced iron, which is collected at the bottom of the furnace body and extracted from the tap slag, and fine ore and coal powder are charged from one end, and the inside is filled with air and fuel. Combined with a rotary kiln-type fine ore reduction furnace in which the charged fine ore is reduced and shaped with carbon and hydrogen in coal and taken out from the other end while being heated by combustion with gas, the fine ore produced in the melting and gasification furnace is This method is characterized in that the gas is used as a fuel gas in a rotary kiln-type fine ore reduction furnace, and the reduced iron produced in the m-type reduction furnace is melted in a melting and gasification furnace.

According to this method, fine ore can be reduced and molded in a rotary kiln-type reduction furnace, so even if fine ore is used as the iron raw material, there is no problem of ventilation obstruction in the melting and gasifying furnace, and the rotary kiln-type reduction furnace In the furnace, the fine ore is reduced with carbon and hydrogen in the coal, so the melting gasification furnace produces high-calorie gas.

Next, one embodiment of the present invention will be described based on the drawings.

(1) is a melting gasification furnace that gasifies coal and melts reduced iron, and (1) is a rotary kiln type reduction furnace that produces reduced iron. 3) and reduced iron supply line (4)
), the O melting gasification furnace (1
) has a tuyere (5) on the side wall of the furnace body for injecting oxygen, steam and pulverized coal, and above the tuyere there is a charging inlet (6) for coke, coal, limestone, etc. It is a vertical furnace with a charging inlet (7) for reduced iron and coke, a gas outlet (1), and a tap slag opening (9) in the lower part of the furnace body. A combustion chamber is formed consisting of a packed bed of coke, coal, limestone, etc., which is charged from the charging port (6) above the tuyere, and a charging port (6) at the top of the furnace is placed on one side of the combustion chamber. A heating section (b) consisting of a packed bed of coke charged from (7) is formed, and a melting fJ consisting of a packed bed of reduced iron charged from the charging port (7) in the upper part of the furnace above the heating section. (C), and a sump (ld) is formed in which the molten iron and slag dripping from the heating section (b) and the molten ash generated in the combustion chamber (a) are stored.

That is, oxygen (2), Jiden (b), and pulverized coal (2) are injected from a separate port (6) to cause a combustion reaction in the combustion chamber (a), and the temperature rises with CO and H as the main components. 1800°C
The above combustion gas was generated and the gas was flowed through the heating section (b) to the melting section (C) above, and after the reduced iron was melted with the heat of the gas, it was taken out from the gas outlet (8), and while the melted The reduced iron and the molten gangue contained therein undergo a carburizing reaction while being dripped through the heating section (b), resulting in a carburization reaction in which Sin is formed in the molten material.

After the orphan reaction has occurred, the coke produced in the combustion chamber 1a), the molten ash of pulverized coal, and the mixed slag of molten lime are collected in the sump (d), and then transferred to the taphole (d). 9
) is extracted from.

Incidentally, the amount of reduced iron that is decomposed and dripped is replenished from the charging port (7), and a constant amount of reduced iron layer is always maintained. Furthermore, the consumed amount of coke in the heating section (b) is replenished through the charging port (7), and a constant amount of coke layer is always maintained. The gas pressure in the furnace is 2 &cf/-~5
Operate at a gauge pressure of l#/ad.

The gas taken out from the gas outlet (8) of the melting and gasifying furnace (1) is a reducing gas containing CO and Hl as main components and having a temperature of about 900"C, and is transferred to a rotary kiln type reduction through the reducing gas supply line (3). Sent to furnace (2).

The rotary kiln type reduction furnace (2) has an input port for powdered ore 1 coal and limestone (to) and an inlet for fuel gas and air at one end of the furnace body, and a reduced iron cutting port (to) at the other end. The fine ore charged into the kiln from the input port (end) is reduced and shaped while being combusted and heated by fuel gas and air blown into the furnace from the inlet α force. It has a structure in which it is cut out from the provided cutting end.

That is, this rotary kiln type reduction furnace uses the gas produced in the melting and gasifying furnace (1) as a fuel gas, and reduces and shapes the fine ore in the furnace with carbon and hydrogen in coal. This σ rotary kiln-type reduction furnace (2) cuts out the Kukanyoku iron, which is melted and gasified ψ (
1), and is charged into the furnace through the reduced iron and coke charging port (1) and melted. Trout indicates coke.

This invention is a method for continuously producing molten pig iron by combining a melting gasification furnace (1) and a rotary kiln type reduction cA (2) like a queen.
The reason why 1) and rotary kiln reduced cF4 (2) were configured separately is as follows.

That is, the present invention aims to produce pig iron in a highly stable and highly efficient manner by gas-reducing iron ore and then melting it, similar to the blast furnace method. However, when trying to perform the gas reduction of ore, l @ cracking, and combustion gasification of coke in one reactor like a blast furnace, the distance (height) between the top of the furnace and the tuyere level is approximately 25 m, and the coke The ore is charged from the top of the furnace and is subjected to loads and shocks while descending. The ore is then melted after being reduced to gas at the top of the furnace.
The melting position is about 20m below the top of the furnace, so the melting point is about 257m.
It will be subjected to an on/- load, and the high-temperature ore that is about to be melted will shrink under the load.

Since a layer called a cohesive zone with extremely poor permeability is formed and causes problems such as ventilation and unloading, a lump ore that does not form a large cohesive zone and has excellent high-temperature softening properties is required.

In addition, if coke deteriorates due to load and impact before it burns out at the tip of the tuyere, it will impede ventilation, so high strength coke is required.

In conclusion, this invention employs a method in which fine ore is reduced and shaped in a rotary kiln reduction furnace, and then melted in a melting and gasification furnace (1). In the Ig decomposition gasifier (1), reduced iron is melted without load in the melting zone 1c) above the heating zone tb) consisting of a coke-filled bed, making it possible to use ore with poor high-temperature softening properties. At the same time, the coke charged from the charging port (6) above the tuyere of the melting and gasifying furnace (1) is rapidly burned and extinguished in the combustion chamber fa) in front of the tuyere, making it possible to use low-strength coke. The coke that is charged through the charging port (7) at the top of the furnace and forms the heating section (b) undergoes a carburizing reaction with the molten iron and slag dripping through the coke packed bed section, causing StO! It is only consumed by reduction reactions such as 6, and is not subjected to the load and impact of unloading as in a blast furnace, so it is possible to use low-strength coke from this point of view as well.

That is, by separating the melting gasification furnace and the rotary kiln reduction furnace, it is possible to use low-quality ore with poor high-temperature softening properties and low-strength coke.

Furthermore, the dissolved gasification melt will be explained in detail.

When burning coke or coal by injecting water s * (II) and pulverized coal (2) from the number (b) to #1,
When the combustion chamber is not filled with coke or coal.

The ratio of CO, gas, H, 0 gas in the combustion gas becomes extremely large, and the combustion gas cannot be used as a fuel. On the other hand, if the combustion chamber is filled with coke or coal, the amount of CO, gas, H, and O gases occupied in the combustion gas decreases, and relatively high-calorie combustion gas can be obtained. If the flow is poor, the raceway at the tip of the blade will be disturbed and a stable combustion condition will not be maintained on the floor. Therefore, in this invention, the combustion chamber (a) is filled with coke or coal to obtain high-calorie gas, and a highly reactive coke-filled bed, that is, the heating section (b) is formed at the front of the combustion chamber to maintain the combustion state. Stabilization of IaIla13i! CO in the gas generated by
The CO production reaction between 2 and coke proceeds, and CO□
In addition, the carburizing reaction of molten iron and the reduction reaction of Fe01S t O in slag, etc. are promoted to obtain pig iron with a low S concentration, and the coke in the coke packed bed is depleted. The amount is replenished from the reduced iron charging inlet (7), and the amount is always maintained at a constant level. In addition, limestone is charged into the coke from above the combustion chamber (a) in front of the bed to stabilize the generated ash.

It flows down to the lower part of the furnace through the combustion chamber (a). Note that the charging ratio of limestone can be such that the amount of Ca0O produced by thermal decomposition of limestone is about 1.5 (CHO/S i OH) with respect to StO, which is the main component of ash in coke and coal.

On the other hand, the combustion gas is heated to a heating section (b) consisting of a coke-filled bed.
As it flows through the coke packed bed to the upper part of the furnace, it melts the reduced iron in the upper part of the coke packed bed, but at the same time the hot metal slag generated there also flows through the coke packed bed to the lower part of the furnace. Therefore, a pool (d) is formed in the lower part of the furnace, where 1 g of pig iron accumulates below, and reduced iron slag and ash flowing from the combustion chamber (a) accumulate above the hot metal.

The reason why oxygen and pulverized coal were used as the fuel to be injected from the 91st feeder (5) is as follows.

When pulverized coal is combusted and gasified, its combustibility strongly depends on the combustion temperature as well as the oxygen concentration in the combustion gas, and if the oxygen concentration increases by 1 inch, the combustibility can be expected to improve by about 6 times. Therefore, in the blast furnace method, when the oxygen level during ventilation is around 21 -, the limit is to use pulverized coal of about 0.3 to 0.4 kF for oxygen inflow, but in this invention, oxygen is used instead of air. Approximately 1 for oxygen I Nm'
It becomes possible to use pulverized coal of up to 165 floors, making it possible to significantly reduce coke combustion consumption. In addition, the gas produced by combustion must be heated to at least 150"C to dissolve the reduced iron.
However, when using air such as in a blast furnace, high-temperature air heated in a hot blast furnace must be used to raise the combustion gas temperature, whereas when using oxygen, air is used. Since the amount of produced gas relative to the amount of combustion reaction is smaller than in the case of combustion, the temperature of the produced gas can be made sufficiently high, and as a result, there is an advantage that a hot blast furnace like the blast furnace method is not required. Also.

By vaporizing liquid oxygen and using it as an oxygen source, it is possible to blow oxygen into a melting and gasifying furnace with a gas gauge pressure of 2 to 5 mm/- without the need for a blower like in the blast furnace method. .

Next, embodiments of the invention will be described.

〔Example〕

Pig iron was obtained by carrying out the operation shown below using the structure shown in Figure 111!1 and one melting and gasifying furnace and one rotary kiln type reduction furnace.

Effective volume of the melting gasifier furnace: 2 350 doors Number of tuyeres: 49 Coke, reduced iron charging inlet: 1 coke, coal 1 limestone charging inlet: 1 side Combustion chambers: 2
4 combustion flaWL inner diameter = 5PR Melting part diameter: 5#I Melting part height: 1 (1 m Gas outlet: 1 piece Furnace internal pressure crab 3-5 I#/ad CB) Rotary kiln Reduction furnace Furnace effective volume: 750w1 Inner diameter :4. Om Total length of kiln: 60m In other words, 336Nrr of oxygen from the tuyeres of the melting and gasifying furnace?
/Pig, t, pulverized coal 336 kt/Pig-
coke (C:88
Chi1 particle size: 40W or less, drum index DI, 85chi)
1201w/Pig, t, limestone 60 groan/Pig-t
is charged from the charging port above the tuyere, and the temperature of the combustion generated gas exiting from the gas outlet of the melting gasifier is 95%.
Cut out reduced iron in equal amounts from the reduced iron cutting port of the rotary kiln type reducing furnace so that the reduced iron drips at 0°CKl. Furthermore, the component that forms the heating part of the decomposition gasification furnace D I l
&-85To) 96 kf/Psg, t was replenished from the reduced iron charging inlet. On the other hand, in the rotary kiln reduction furnace, fine ore (T-Fe 62%)
1530kf/Pig-t.

Stone grain powder (Fe 52gj, Ash 15%) 385
19/Pig-t.

Add 9/Pig-t to 200 limestone,
At the same time, we created reduced iron by blowing in CO gas and air at a temperature of approximately 900°C generated in a melting and gasifying furnace, and then melting the reduced iron in the melting and gasifying furnace.The following results were obtained. became.

The pressure of oxygen injected from the tuyeres of the melting and gasifier is 51y/-
Therefore, the position and composition of the gas coming out from the gas outlet of this gasifier are 1069Ny<44g・t, CONia5
%, Hz: 22%, the amount of reduced iron charged into the melting gasifier is 1 a 16 I#/Ptg-t, the amount of m-rich cosis is 96 kf/Plg-t, and as a result, the amount of dissolved gas The amount and composition of molten pig iron extracted from the taphole of the heat treatment furnace are 1 ton, C: 4%, and St: 0.2%.

The total amount of s:o, oa%, and other impurity elements was 0.3g, the temperature was 1500°C, and the slag amount was 3501w/l.

If we organize the above operations, to produce 1 ton of pig iron,
216kf low quality coke, 4211# coal, 33
It will require 6 o'clock pulverized coal, 336 Nyrt' of oxygen, 60 - of limestone, 1530 kt of fine ore, and at the same time 2900 Kctal/N- of gas of 1069
Since Ni is produced as a by-product, the actual energy consumption is 427
4Mcm#, 572Mc as oxygen production energy
Even including aJ, it becomes 4846 Mctal/t ◎By the way, in the blast furnace method, about 2800hi per ton of pig iron
It requires energy consumption of c, l, which is about 2000 Mcal less than the method of this invention, but the pre-process 1j
The amount of coke used, which requires a large amount of energy per liter, is approximately 5
Considering that it requires high quality coke and agglomerate ore, which is higher than the coke usage of this invention, fine ore can be used.

It can be seen that this method of the invention is superior to the blast furnace method in that it can obtain a large amount of high-calorie gas.

[Brief explanation of drawings]

The drawings are schematic diagrams showing one embodiment of the present invention. In the figure, 1... melting gasifier, 2... rotary kiln reduction furnace, 3... reducing gas supply line, 4... reduced iron supply line, 5... pulverized coal injection tuyere, 6...
Coke, coal 2, limestone, etc. charging inlet, 7... Reduced iron, coke, etc. charging inlet, 8... Gas outlet, 9... Tapping slag port, lO... Oxygen, 11... Water vapor, 12...pulverized coal, 13...coke, coal 9 limestone, 14...
Coke, 15...Powder/ore 1 Coal 9 Limestone inlet,
16...Reduced iron cutting port. 17... Fuel gas and air inlet, 18... Powdered ore 1
Charcoal. limestone. Applicant: Sumitomo Metal Industries, Ltd.

Claims (1)

[Claims] The side wall of the furnace body has a wall for injecting oxygen, steam, and pulverized coal, and the upper part of the tuyere has an inlet for charging coke, coal, limestone, etc., and the lower part of the furnace body has a reduced iron, coke charging inlet, and gas outlet. body F
A combustion chamber is formed in front of the tuyere with a packed bed of coke, coal, limestone, etc., which is charged from the charging port above the tuyere, and the furnace is equipped with a taphole in each section. A heating section consisting of a packed bed of coke charged from the upper part of the furnace is formed at the front, and a melting section consisting of a packed bed of reduced iron charged from the upper part of the furnace body is formed above this heating section, and the melting section is formed from a packed bed of reduced iron charged from the upper part of the furnace body. Coke, coal, and pulverized coal injected through the tuyere are simultaneously combusted and gasified with oxygen and steam injected through the tuyere, producing - high-temperature combustion gas containing carbon oxide and hydrogen as main components.
Coke and coal ash and limestone are thermally decomposed to produce molten slag, and the combustion gas passes through a heating section in front of the combustion chamber and dissolves reduced iron in a melting section consisting of a reduced iron packed layer above the heating section. After that, the molten slag is collected from the gas outlet, and the molten slag produced in the melting section is collected at the bottom of the furnace body together with the molten reduced iron that drips through the heating section consisting of a coke-filled bed, and is collected at the bottom of the furnace body. A molten ore gasifier is used to extract fine ore from one end and coal powder is charged from one end, and while the interior is heated by combustion using static electricity and fuel gas, the charged ore powder is reduced with carbon and hydrogen in the coal.・In combination with a rotary kiln type powder ore reduction furnace which is molded and taken out from the other end, the gas generated in the melting and gasification furnace is used as fuel gas for the rotary kiln type powder and stone reduction furnace, and in the reduction furnace. A method for producing pig iron characterized by melting the produced reduced iron in a melting and gasifying furnace.