JPS63216908A - Bach type production for molten metal - Google Patents

Abstract

PURPOSE:To improve thermal efficiency, by utilizing reducing gas generating by burning carboneous material in packing layer in a furnace to the reduction of ore and burning by produced gas, which does not reduct ore, by combustion- aiding gas blowing to the packing layer, to utilize as sensible heat. CONSTITUTION:The carboneous material 6 and the ore 7 are charged in the cylindrical furnace 1 to form the packing layer 9. Next, the combustion-aiding gas (for example, O2) is blown from the combustion-aiding gas blowing nozzle 3 arranged at the furnace bottom of the above cylindrical furnace 1, to burn the carboneous material 6. By this method, high temp. reducing gas is generated and also the ore 7 is prereduced. Next, the combustion-aiding gas is blown in the above packing layer 9, to burn the by produced gas, which is not contributed to the reduction of ore 7, and preheat the ore 7. Further, under remaining condition of the carboneous material 6 in the furnace 1, by blowing the combustion-aiding gas, molten iron and molten slag are extracted from tapping hole 4 for the molten iron and slag.

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a method for producing pig iron without using a blast furnace method, and more specifically, it adopts a batch refining method and uses low-quality raw materials to efficiently produce pig iron. This invention relates to a method for producing hot metal.

Prior Art and Its Problems The mainstream iron making method at present is the blast furnace method. The main chemical reactions in the blast furnace method can be expressed by the following formulas 0 to 0.

C+1/20e-+CO+29.410 kcal/K
fllOI C,・,■F@203 +CO→2FeO
+CO2+ 2.330 Kd/not Fe2O2
"・■FsO+CO-+Fe+COz + 4.390 Kcal/Kmol FQO"・■F
@O+C-+Fs+CD -33,790 cal/K11101 FQO...
■In other words, coke charged from the top of the furnace falls in front of the tuyere, is converted into high-temperature reducing gas by the reaction of formula (■), and in the process of rising in countercurrent to the falling ore, the sensible heat of the gas and Chemical energy is applied sequentially from the bottom to the melting reduction of the remaining iron oxide (
0 formula), melting of pre-reduced iron and pre-reduction of iron oxide (■,■
formula) and used for preheating ore. In this way, the blast furnace method achieves high thermal efficiency and reduction ability by countercurrent flow of gas and ore.

However, in order to achieve a stable countercurrent reaction of gas and ore in a single vessel, high-strength, low-reactivity coke and high-strength,
Since highly reducible ores are required, careful selection of coking coal and iron ore, as well as large pre-processing equipment such as coke ovens, sintering machines, and pellet equipment, are required to ensure effective use of resources, energy conservation, and environmental protection. This causes an increase in costs.

To address these problems, a smelting reduction method has been developed in which iron ore is reduced using a solid reducing agent heated and melted, with the aim of easing raw material constraints and simplifying pre-treatment equipment.

The chemical reactions of the melt reduction method are expressed by the following formulas (1) and (2).

F@t03 + 3C42Fm+ 3cO-108,0
90 to d/not Fe2O2...■ω+1/20
．． →CO2+67.590Kcal/Kmol Co
...■ That is, contrary to the blast furnace method, iron oxide is first melted and reduced with carbon in the molten state (equation 0).

Although this reaction is accompanied by a large endotherm, it is compensated for by the combustion heat of CO gas produced as a by-product in the melting reduction reaction, as shown in equation 0.

In this way, in the initial stage, attempts were made to alleviate constraints on raw material quality by reducing iron oxide in a liquid state.
It was a melt reduction method typified by the llac method.

However, in the case of the smelting reduction method, if the Equation 0 reaction is promoted in an attempt to achieve high energy efficiency, the reducing atmosphere in the furnace decreases, creating a state in which iron oxide cannot be sufficiently reduced, resulting in a decrease in iron yield. However, these attempts were not put into practical use because of the problem of damage to refractories caused by iron oxides and iron oxides in the slag.

As countermeasures against this problem, there are currently attempts to strengthen the preliminary reduction of iron oxide in another furnace (COIN method, CIG method, etc.), and attempts to use electric power instead of the 0 type as heat compensation for smelting reduction (E
I red method, l n red method, etc.), but while all of these methods ease the raw material constraint conditions, they result in complication of the process.

This invention aims to solve the problems of the blast furnace method and the smelting reduction method, and to propose a simple method for producing hot metal with high energy efficiency using inferior raw materials. .

Means for Solving the Problems This invention proposes a method for efficiently producing hot metal using low-quality raw materials by employing a batch refining method as a means for solving the above-mentioned conventional problems. The gist of this method is to use a cylindrical furnace with openings at the top for charging raw materials and gas recovery, and a combustion-supporting gas injection nozzle and hot metal slag extraction port at the bottom. A packed bed of wood and ore is formed, and the carbon material is combusted with combustion-supporting gases such as air and oxygen blown in from the bottom blowing nozzle to generate high-temperature reducing gas.
The ore is pre-reduced using the reducing gas, and combustion-supporting gases such as air and oxygen are blown into the packed bed of carbonaceous material and ore using a top blowing lance to burn gases that do not contribute to the reduction of the ore. is preheated, and with the carbonaceous material remaining in the furnace, combustion-supporting gas is blown into the bottom of the furnace and the packed bed of ore and carbonaceous material through the bottom blowing nozzle and top blowing lance, and the carbonaceous material is combusted. The present invention provides a batch method for producing hot metal, which is characterized by melting and refining pre-reduced ore and extracting the generated hot metal and slag from a hot metal slag extraction port.

The blast furnace method is a continuous process in which the main body of reduction is gas reduction (
(■, ■), high-quality ore and coke were required. On the other hand, the smelting reduction method mainly focuses on smelting reduction, and uses the smelting reduction heat absorption as the heat generated by combustion of the by-product gas (equation 0).
As a result, the reduction ability decreased.

Therefore, in this invention, we incorporate both the 0-0 reaction in the blast furnace method and the reactions in the smelting reduction method and the reactions in the This paper proposes a method that allows the use of inferior raw materials by performing preliminary reduction, melting, and smelting reduction, and that can produce hot metal with high energy efficiency and iron yield.

In this invention, the batch treatment method is adopted in order to use inferior quality carbon materials and ores.

The operational drawings are manufacturing process diagrams schematically showing one embodiment of the present invention.

First, the reaction vessel used in this invention has an opening (2) at the top for charging raw materials and recovering gas, and a bottom blowing nozzle (3) at the bottom for blowing combustion-supporting gas such as air or oxygen. ) and a cylindrical furnace (1) having a hot metal slag extraction port (4).

The raw materials used are mainly carbonaceous materials and ores. The carbon material may be coke, molded bottom, or coal, and the particle size is preferably 5 mm or more. The ore may be any lump ore, fired pellet, raw pellet, sintered ore, etc., and the particle size is preferably 2 mm or more. In addition, limestone, dolomite, and other slag-forming agents are used as necessary.

That is, first, carbon material (6), ore (7), and if necessary, a slag-forming agent (8) are charged into the furnace through the upper opening (2) of the cylindrical furnace (1), and a packed bed is formed in the furnace. (9) is formed. In this case, the two methods of charging force include charging the carbonaceous material, ore, and slag-forming agent in layers, or charging them in a mixed manner, but it is preferable to concentrate the carbonaceous material at the bottom of the furnace ( Diagram a).

Next, combustion-supporting gas (0) such as air or oxygen is injected from the bottom blowing nozzle (3) to ignite the carbonaceous material (6). As the combustion of the carbonaceous material progresses, CO2 in the combustion generated gas,
) 120 decreases, and through the reaction shown in the following equation 0, CO and H
A reducing gas containing 2 as the main component is produced (Figure b).

Cm Hn +T O2-1tl Co + 282
...■ When the above reaction becomes stable, increase the number of combustion-supporting gas injection stations from the bottom of the furnace, and insert the top blowing lance (5) into the filling layer (9) to inject air, oxygen, etc. Inject combustion-supporting gas. At this stage, the temperature of the ore in the packed bed is low. Therefore, the combustion reaction shown below occurs.

ot+co ()12> =C0z (H2O) +
67590 (57800) ad/KIIIO1Co
(H2) ...■This combustion heat heats the ore and raises its temperature, and a reduction reaction (■, [Co., Ltd.] equation) occurs (Figure C).

F8□03 +CD ()12)→2FaO+COz
(H2O)+2330(-7460)Kcal/Kf
llOI F11203...■FsO+CD ()
12) →Fe+C02()120 )+4390(-
5400) Kcal/KmOI FsO...■ That is, at this stage, the reducing gas generated by the 0-type reaction at the bottom of the furnace is used as a fuel and reducing agent to promote preheating and preliminary reduction of the ore. At this time, 0 at the bottom of the furnace
The total amount of Co and H2 gas produced by the reaction of the formula is CO2
, Co in the gas that is converted to H2O and exhausted, H2
The amount of combustion-supporting gas (O2) blown into the packed bed (9) is adjusted so that the amount becomes zero.

After that, by continuing to blow combustion supporting gas from the bottom blowing nozzle (3) and top blowing lance (5) with the carbonaceous material remaining in the furnace, the pre-reduced ore is produced by burning the carbonaceous material. The temperature reaches the melting point and the ore begins to melt. At this stage, CO2 is generated by the reaction of 0 to 0 formula,)
(AO reacts with C in the carbonaceous material again and is converted to Co and H2. Therefore, at this stage.

In this case, even if the amount of oxygen sent from the bottom blowing nozzle (3) and the top blowing lance (5) is increased, the temperature of the exhaust gas (11) will only rise excessively, and the increase in CO2 and H2O in the exhausted gas will increase. Since the degree of oxygen decreases, the amount of oxygen sent from the bottom blowing nozzle (3) and the top blowing lance (5) is reduced.

During this time, the dissolution of the ore progresses, and the iron oxide remaining in the slag undergoes a reaction with C in the carbonaceous material as shown in Equation 11 below, and is reduced (Figure d).

FsO+C→Fs+co-33790Kcal/KmO
I FaO・=■After that, the entire amount of ore is dissolved and reduced,
Hot metal and slag are produced in the furnace. Furthermore, by charging an excessive amount of carbon material at the time of charging the raw materials, carbon material also coexists in the furnace. Whether or not the reduction of the entire amount of ore has been completed can be confirmed, for example, by checking that the amount of 01 in the IM and the amount of 01 in the discharged gas match, so at this point the acid feed is stopped and the molten pig iron (12) and slag (1
3) is extracted from the hot metal slag extraction port (4) (Figure e). Here, it is desirable that the carbonaceous material remaining in the furnace be left as is as it is carried over to the next time.

The reaction of type 0 in the method of this invention described above is the same as the reaction of type 0 in a blast furnace. Also ■, @l.

The reaction of Equation 0 is the same as the reaction equations (1), (2), and (2) in a blast furnace. In other words, it can be considered that it consists of the same reactions as a blast furnace. However, whereas the blast furnace is operated continuously, this invention is operated batchwise. By adopting this batch method, it is possible to use inferior quality carbon materials and ores that cannot be used in blast furnaces.

That is, unlike coke in a blast furnace, it is not necessary to form a coke-filled bed in the lower part of the furnace for a long time, and most of the carbonaceous material disappears at the final stage of operation. Therefore, strength and strict particle size control are not required. On the other hand, the reducibility of the ore does not matter. The reason for this is that in the case of ores with excellent reducibility, the ore is reduced with reducing gas generated in the lower part of the furnace, and gas that does not contribute to reduction is burned to preheat the ore (Figure C). The reaction of equation 0 is strengthened, and the generated Co and H2 gases
, Ore can be reduced by [stock] formula.

On the other hand, in the case of ores with poor reducibility, the reaction of formula 0 is promoted at the stage shown in Figure (C) above to dissolve them at an early stage, and the process proceeds to the pre-reduced ore melting and refining process (Figure d). This is because it can be reduced by the reaction of formula (2).

Here, in the case of ores with good reducibility, the reaction mode is mainly the formulas ■, ■, and ■, and the blast furnace method ■, ■.

■It is the same as the formula. On the other hand, in the case of ores with poor reducibility, the reaction mode is mainly ``■'' and ``stock'' formulas, which are the same as the ``2'' and ``2'' formulas in the smelting reduction method. However, in this case, in the smelting reduction method, formulas (1) and (2) proceed simultaneously, which caused a decrease in reducing ability, but in the case of this invention,
By adopting a batch operation system, the reactions of Equations and Equations 0 are temporally divided into the reduction and preheating stage of the ore (Figure C) and the melting and refining stage of the pre-reduced ore (Figure d). There is no loss of ability. Of course, the sum of the reactions of formulas ■, ■, [stock] and the sum of the reactions of formulas ■ and ■ are equivalent as a whole, and both can be expected to have high energy efficiency (gas utilization rate) comparable to the blast furnace method. Become.

As described in detail, this invention uses a batch operation procedure, forming a packed bed of ore and carbonaceous material in the furnace, blowing combustion-supporting gas from the bottom of the furnace, and burning the carbonaceous material. The generated reducing gas is used to reduce the ore, and the Co and H2 gases that were not used to reduce the ore are OIed into the packed bed of ore and carbonaceous material! It is possible to produce hot metal with high energy efficiency without impairing reduction ability using inferior quality carbonaceous material and ore by injecting and combusting it and using it openly. Therefore, according to the present invention, the great effect of significantly reducing the cost of producing pig iron is achieved.

EXAMPLE 7 The process of the invention was carried out in a t/charge top-bottom blown converter.

At that time, as ore F1120386%, gangue 13.8
%.

5L0226% in gangue, Al! 20312%, Ca
Use 100% O49%2 particle size of 2 mm or more,
Carbon material: 87.5% carbon, 10% ash, 2 particle size: 1101
Two cokes of T1 or higher were used.

First, 11.2 tons of ore and 3.7 tons of coke were charged into a sufficiently heated converter to form a packed bed of ore and coke. However, the coke at the bottom of the furnace is heated at 1°C.
was charged alone, and a mixture of coke and ore was charged on top of it.

Next, 1000 Nm'A1 of air was blown from the bottom blowing nozzle. About 5 minutes after blowing, CO was detected in the exhaust gas, so the amount of air from the bottom blowing nozzle was reduced to 386ONm34.
At the same time as increasing the amount of Air was blown from a top-blowing lance inserted into the x layer with the amount of air blown so that Co and 02 in the exhaust gas were zero. The time required during this period was approximately 60 minutes, and the amount of air blown into the filled layer was 650 Nm3+ on average over the 60 minutes.

In the latter half of the above process, Co in the exhaust gas does not disappear even if the amount of air blown into the packed bed is increased, so the temperature reaches a high enough temperature that the coke reacts with the generated CO2 and is converted to co. (1080″C or higher), so we switched the bottom blowing and air blowing into the packed bed to 02 and continued air blowing.After that, in about 40 minutes, the amount of oxygen blown and the amount of oxygen in the discharged gas decreased. Since we are almost in agreement,
Oxidation was stopped.

The average amount of oxygen sent from the bottom blowing nozzle during this period was 1436N.
m3+, the average amount of oxygen sent to the packed bed was 212 Nm'+. Also, during this period, the average utilization rate CD/C of the gas discharged
D+C02 was approximately 50% and 4914 Md of gas was recovered.

Next, when the oxygen supply was stopped and the hot metal and slag accumulated in the furnace were extracted, 7 tons of hot metal and 1.89 tons of slag were recovered, and approximately 1.8 tons of coke remained in the furnace.

The temperature of the obtained hot metal was 1500°C, C was 3.5%, SL was almost zero, and S remained below 0.1%. In addition, the slag contains approximately 40% CaO, approximately 31% 5LOt, and M2O.
315%.

FsOO was 5% or less, So was 8%.

Table 1 shows the amount of raw fuel used per ton of pig iron.

Table 1 Also, the total time required for refining was 1 hour and 45 minutes, and including the time required for hot metal slag extraction and charging, it was about 2 hours per charge.

In addition, not only when coke was used as the carbon material, but also when briquette coal and lump coal were used, although the amount of carbon material used increased somewhat, it was possible to operate satisfactorily.

As is clear from the above examples, the method of the present invention was able to produce hot metal using raw materials with fine particle diameters that cannot be used in the blast furnace method, and with an energy consumption rate comparable to that of the blast furnace method.

[Brief explanation of the drawing]

The drawings are manufacturing process diagrams schematically showing one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Cylindrical furnace, 2... Opening, 3... Bottom blowing nozzle, 4... Hot metal slag extraction port, 5... Top blowing lance, 6... Charcoal material, 7... Ore, 9...
- Filled bed, 12... Hot metal, 13... Molten slag.

Claims (1)

[Claims] A cylindrical furnace with an opening for charging raw materials and gas recovery at the top, a combustion-supporting gas injection nozzle and a hot metal slag extraction port at the bottom of the furnace is used, and a packed bed of carbonaceous material and ore is placed inside the furnace. The carbonaceous material is combusted by the combustion-supporting gas blown in from the bottom blowing nozzle to generate high-temperature reducing gas, the ore is pre-reduced by the reducing gas, and the ore is further reduced with the top-blowing lance. The ore is preheated by injecting combustion-supporting gas into the packed bed of ore to combust the gas that does not contribute to the reduction of the ore, and with the carbonaceous material remaining in the furnace, the bottom of the furnace is blown through the bottom blowing nozzle and top blowing lance. A combustion-supporting gas is injected into a packed bed of ore and carbonaceous material, the carbonaceous material is combusted, the pre-reduced ore is melted and refined, and the generated hot metal and slag are extracted from a hot metal slag extraction port. A batch production method for hot metal.