JPS637305A - Operating method for blast furnace - Google Patents

Abstract

PURPOSE:To enable continuous operation without equipment trouble and to obtain an excellent low-Si operation efficiency at a decreased coke ratio and stable descending by mixing iron ore powder and heavy oil in a slurry state and blowing the same into a blast furnace through blast furnace tuyeress. CONSTITUTION:The iron core powder stored in a service hopper 1 is fed out at a prescribed rate through a rotary feeder 2 provided to the lower part of the hopper 1 and is supplied to a mixing tank 3 where the iron ore powder is uniformly mixed with a prescribed amt. of the heavy oil from a heavy oil supply line 4. After the slurry composed of the iron ore powder and heavy oil to a prescribed concn. is prepd., the slurry is distributed and fed from the lower part of the tank 3 to the respective tuyeres 8 through a distributor 6 by a slurry pump 5 and is blown from slurry blow nozzles 7 into the blast furnace 9. The blowing of the iron ore powder from the tuyeres 8 without inducing piping wear is permitted and further, the execution of the long-period low-Si operation under the stable descending is permitted. The excellent effect of reducing the consumption of the slag forming agent in a steel making stage is obtd.

Description

[Detailed Description of the Invention] Industrial Field of Application This invention is directed to S1 in hot metal of a blast furnace under stable unloading.
The present invention relates to a blast furnace operating method that can reduce the SL, and more specifically to a blast furnace operating method that aims to stabilize low SL operation by injecting iron ore powder in the form of a slurry from the blast furnace tuyere.

Technical Background In the transfer of Sj into hot metal in a blast furnace, a gas-metal reaction mediated by SLO gas plays a major role, rather than a slag-metal reaction in the hearth sump. S
The transfer of SL into hot metal via LO gas is as follows:
It is roughly divided into two processes (Tetsu to Hagane Vo 58 19722
(page 19).

That is, ■ the process of producing SjO gas through the reaction of 5Lo2, whose main source is ash in coke, with fixed carbon in coke in the high temperature, low oxygen partial pressure region near the raceway;
■SL contained in the rising gas flow below the softened cohesive zone
This is the process of SL transfer into the hot metal due to the reaction between the O gas and the carbon in the dripping hot metal, and both processes are expressed by the following reaction formula.

(SLO2) +c =SLO(g)+CO((])・
・・・・・・■SLO ((1) Ten gongs = Gaju Co(g)
・・・・・・■Here, 0 is a conventional notation that indicates that the compound is present in the slag, and the underlined element name is a conventional notation that indicates that the component is present in the hot metal. . Therefore, as a method for controlling the SL concentration in hot metal, SL
There is control of the O gas generation reaction and control of the SL transfer reaction into the hot metal.

In actual blast furnace operation, the former control means is 5LO2 brought in before the tuyere by controlling the ash content in coke.
SL by ffi control and tuyere front temperature control.

Control of gas generation rate, etc. is being implemented. The latter control means include controlling the cohesive zone level by controlling the coke ratio based on charge distribution control, and controlling the cohesive zone level by controlling the reducibility and softening cohesive properties of sintered ore (iron and steel V
o r168 1982, p. 219).

Prior art and its problems As a method of controlling the SL concentration in hot metal, in addition to the above-mentioned control means based on the Sj transfer mechanism into hot metal in the blast furnace, iron oxide is injected from the blast tuyeres, and the following A so-called in-furnace desiliconization method for oxidizing Sj in hot metal through a reaction has been developed (Japanese Patent Application Laid-Open No. 56-29601; Japanese Patent Application Laid-Open No. 58-1999)
77508>.

SL+ 2FEIO= (Sin2> + 2Fa-・
...■ In the case of this control means, if the above reaction is appropriately controlled, the SL concentration in the hot metal can be controlled immediately before tapping, and the S concentration in the hot metal can be easily managed.

However, the conventional method of controlling the SL concentration in hot metal by blowing iron oxide through the tuyere using gas transportation is disadvantageous in terms of cost due to high powder drying equipment costs and operating costs. There was a problem in that wear progressed in the distributor and bent pipe parts, making it difficult to operate stably over a long period of time.

Purpose of the Invention The present invention was made in order to solve the above-mentioned problems in the conventional blast furnace operating method for the purpose of reducing the use of slag-forming agents in the steel manufacturing process, and it does not require powder drying. A blast furnace operating method that makes it possible to inject fine iron ore from the tuyere without causing piping wear, which also leads to a reduction in the coke ratio, and which allows a large low Sj operation effect to be obtained under stable loading conditions. We aim to provide the following.

Means for Solving the Problem This invention mixes iron ore powder and heavy oil to form a slurry, and injects this iron ore powder/heavy oil slurry through the blast furnace tuyere, thereby reducing costs by eliminating the need for the powder drying process. ,
The aim is to stabilize operations by solving the problem of piping wear.

The reason why the heavy oil slurry method was adopted as the method for injecting iron ore powder into the blast furnace is as follows.

In other words, by mixing iron ore powder and heavy oil to form a slurry, there is no need to dry the powder, and the equipment and operating costs required for this are eliminated, making it cost-effective compared to gas transportation. One thing is that in the case of zero-heavy oil slurry, there is almost no piping wear, so powder can be stably supplied over a long period of time.

On the other hand, blast furnace operation began in the 1960s by injecting large amounts of liquid fuel such as heavy oil and tar through the tuyere, resulting in a low coke ratio.
The trend has been towards high iron production ratio operations. After that, in the early 1970s, the energy price system changed significantly due to the soaring price of crude oil, and all-coke operation became the mainstream for blast furnace operations. However, from the latter half of 1985, due to the effects of the strong yen and the reduction in crude oil prices in oil-producing countries, it became once again more advantageous in terms of cost to use heavy oil as an energy source in the steelmaking process and lower the coke ratio. There is.

Therefore, the iron ore powder/heavy oil slurry not only has the advantages of the powder supply system described above, but is also very effective in terms of blast furnace operation.

In other words, increasing the amount of hydrogen input by injecting heavy oil slurry is effective for low SJ operation due to a decrease in the temperature in front of the tuyere, and improves the melting and dripping properties of ores because the hydrogen reduction reaction progresses at the bottom of the shaft. This has the effect of roughly reducing the amount of coke powder near the raceway, which greatly contributes to stabilizing the unloading.

Furthermore, in heavy oil slurry injection, heavy oil is injected into the tuyere together with iron ore powder, which contributes to reducing the coke ratio of the blast furnace.

Note that the mixing ratio of iron ore powder and heavy oil is not particularly limited as long as it is within the liquid limit of the slurry, and the mixing ratio of iron ore powder can be up to about 80% by weight. Therefore, the ratio between the two is determined within this range based on the needs of the steel manufacturing side (Sj sub-control coke ratio reduction in hot metal).

Disclosure of the Invention by Drawings FIG. 1 is a schematic diagram showing an embodiment of the present invention.
) is a service hopper, (2) is a rotary feeder, (3) is a mixing tank, (4) is a heavy oil supply inlet, (5) is a slurry pump, (6) is a distributor, and (7) is a slurry blowing nozzle. , (8) shows the tuyere, and (9) shows the blast furnace, respectively.

That is, a predetermined amount of iron ore powder stored in a service hopper (1) is cut out through a rotary feeder (2) provided at the bottom of the hopper and supplied into a mixing tank (3). The iron ore powder is uniformly mixed with a predetermined amount of heavy oil supplied from the heavy oil supply line (4) to form an iron ore powder/heavy oil slurry of a predetermined concentration. After that, each tuyere (8) is pumped from the bottom of the mixing tank (3) by a slurry pump (5) through a distributor (6).
The slurry is distributed and flowed into the blast furnace (9) from the slurry injection nozzle (7).

Note that the slurry blowing nozzle (7) is installed at each tuyere, and one or more distributors (6) may be installed as needed.
In some cases, they are installed in multiple stages. In addition, one or more systems from the service hopper (1) to the slurry pump (5) are installed as required for each taphole direction.

Example A The results when iron ore powder having the composition shown in Table 1 is mixed with heavy oil and injected into a blast furnace (inner volume 5050 m') are compared with those when injected using a conventional gas transportation method. It is shown in Table 2.

In this example, in period A, iron ore powder was injected from the blast furnace tuyere using conventional gas transport for the purpose of reducing 5ila degree in hot metal. The amount of blowing at that time was 40kg/p-
At T, the SL concentration in the hot metal decreased to 0.17%, but the number of slips did not decrease. Additionally, due to powder injection using gas transport, equipment troubles occur due to piping wear.
Transportation had to be stopped and equipment repaired about four times a month.

On the other hand, in period B, the method of this invention was applied to inject iron ore powder and heavy oil slurry into a blast furnace. At that time, the amount of iron ore powder in the slurry is 40kq/Ko.The amount of heavy oil in 1 piece is 30kL3.
/1)-T, and TS/p-T of iron ore powder/heavy oil slurry was blown into the total 70. As a result, SL in hot metal
As the concentration decreased to 0.16% and the hydrogen input amount to the blast furnace increased to 8.1 kq/p-T, the unloading of the charge in the blast furnace became stable and the number of slips decreased. Furthermore, the coke ratio was lowered, leading to a reduction in energy costs.

In addition, since the method of the present invention involves transporting heavy oil slurry, wear on piping is significantly reduced, and continuous operation is possible without equipment trouble by inspecting the equipment once a month during regular blast furnace air shutdown. there were.

Margin below Table 2 The number within 0 indicates the amount of powder in the heavy oil slurry.

As described in detail, according to the method of the present invention, iron ore powder can be injected from the tuyere without drying the powder and without causing piping wear, thereby reducing setup costs and operating costs. This has the effect of not only reducing the amount of water used, but also enabling continuous operation without equipment trouble. In general, as the coke ratio decreases, it becomes possible to carry out long-term low Sj operation with stable loading, which has a great effect on reducing the use of slag agents in the steelmaking process.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the present invention. 1... Service hopper, 2... Rotary feeder, 3... Mixing tank, 4... Heavy oil supply line, 5... Slurry pump, 6... Distributor, 7...
...Slurry injection nozzle, 8...tuyere, 9...blast furnace. Figure 1 Secondary block
Including. Voluntary procedure amendment October 2, 1985 1, Indication of the case 1986 Patent Application No. 149959 2, Name of the invention Blast furnace operating method 3, Person making the amendment Relationship to the case Applicant address Kitahama, Higashi-ku, Osaka City 5-15 Name (211) Sumitomo Metal Industries Co., Ltd. 4, Agent 5, Column 6 for detailed explanation of the invention in the specification subject to amendment, Contents of amendment ``Steelmaking Knight'' on page 6, line 14 of the specification of the present application. "Pigmaking side"-3■

Claims (1)

[Claims] A blast furnace operating method characterized by mixing iron ore powder and heavy oil to form a slurry, and injecting this iron ore powder/heavy oil slurry through the blast furnace tuyere.