JPS62228411A - Method for transferring powdery granule to be added to metallurgical furnace - Google Patents

Abstract

PURPOSE:To utilize heat energy in exhausted gas and reduce iron ore with good productivity, by preheating powdery iron ore with high temp. exhausted gas in converter at charging iron ore, cokes to metallurgical furnace such as converter, supplying oxygen by oxygen top blown lance to reduce and melt iron ore and manufacture pig iron. CONSTITUTION:Molten pig iron is charged into a top blown converter 1 providing bottom blowing tuyere, oxygen is blown from bottom blowing tuyere and a top blowing lance 7, then lump cokes are thrown into furnace from a converter hole 2 to raise temp. of molten pig iron to about 1,520 deg.C by the combustion. Next, iron ore fines of <=200 mesh are passed from an iron ore dispenser 6 through a piping 5 for pneumatically carrying powdery granule of an exhausted gas duct 4, heated with high temp. exhausted gas, the blown from the lance 7 and reduced to molten pig iron by cokes. Since ore fines are heated to high temp., supplying velocity to converter can be enlarged, and molten pig iron can be manufactured from iron ore with superior productivity while utilizing heat energy in exhausted gas.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for transporting granular material added to a metallurgical furnace, and particularly aims to reduce the energy used in metallurgical furnace operation while simplifying exhaust gas treatment. It is something to do.

(Prior Art) In the operation of a metallurgical furnace, when supplying raw materials, powdery raw materials are blown through pneumatic piping.

For example, in a smelting reduction furnace, powdery ore and carbonaceous materials are
Further, in the scrap melting furnace, granular carbonaceous materials are injected, and in the LD converter, CaO powder and the like are injected.

(Problem to be solved by the invention) However, in the past, powder was supplied as a gas at room temperature, so extra thermal energy was required to raise the temperature of the powder. In other words, there remained a problem in that the use of carbonaceous materials and refining gas as a heat source would increase.

Furthermore, since there are restrictions on the powder supply equipment, there are cases where the supply of heat is insufficient and the reaction rate is restricted.

This invention advantageously solves the above-mentioned problems, and by effectively utilizing the thermal energy of the exhaust gas, the heat source for raising the temperature of the additive powder can be significantly reduced, and at the same time, the exhaust gas can be easily treated. The purpose of this study is to propose a method for transporting powder and granules added to a metallurgical furnace.

(Means for Solving the Problems) That is, in the present invention, when adding powder and granules to a metallurgical furnace, a part of the piping for the pneumatic powder and granules is disposed in the exhaust gas flue of the metallurgical furnace, This is a method for transporting powder and granular material added to a metallurgical furnace, which comprises preheating the powder and granular material using the sensible heat of exhaust gas or combustion heat, and then introducing the powder into the furnace.

(Function) While the powder and granules pass through the pneumatic powder and granule pipe installed in the exhaust gas flue, they are preheated by heat exchange with the exhaust gas and become thermally advantageous, while the exhaust gas is It is heated and the temperature drops, making it easier to process.

(Example) An example of the present invention carried out in a 5-ton scale converter using the melting reduction equipment shown in FIG. 1 and the lance shown in FIG. 2 is shown below.

In the figure, number 1 is a top-bottom blowing converter, 2 is a furnace opening, 3 is a dust collection hood, and 4 is an exhaust gas treatment duct. After the CO gas generated in the furnace is completely combusted by drawing in outside air from the furnace, the combusted gas is introduced into the exhaust gas flue (in this example, the exhaust gas treatment duct 4).

Further, 5 is a pipe for pneumatic powder and granular material arranged in the duct 4;
6 is a powder dispenser, 7 is a top blowing lance, and the powder and granules cut out from the dispenser 6 are transferred to piping 5.
The mechanism is such that the air is fed to the top-blowing lance 7 via the inside.

Furthermore, the top blowing lance 7 has a structure that supplies the refining gas and the granular material separately, and 8 is a flow path for the refining gas, 9 is a flow path for the granular material, and 10 is a flow path for cooling water. .

Example 1 Now, using the above-mentioned equipment and lance, a melting reduction operation was carried out according to the following procedure.

First, approximately 5 tons of hot metal is charged into the converter 1, and then a total of 2 tons of refining gas is supplied from the top blowing lance 7 and the bottom blowing tuyere.
Pure oxygen gas was blown at 0 N+n3/min.

After 5 minutes, pour 10 to 20 pieces of coke from furnace port 2.
Started adding intermittently at a rate of 0 kg/min, 13 minutes 3
After confirming that the melting temperature had reached 1520°C after 0 seconds, the iron ore powder crushed to 200 mesh or less was started to be cut out from the dispenser 6, and was blown into the hot metal from the top blowing lance 7 while passing through the pipe 5. .

The coke supply rate was kept constant at the above-mentioned 20 kg/min, and with reference to the hot metal temperature measurements taken every 5 minutes, multiple iron ore powders were continued to be supplied to the extent that the temperature did not fall below 1400°C. . If the iron ore powder supply rate can be increased, the iron recovery rate will be increased accordingly, which will improve productivity.

Table 1 shows the feed rate of iron ore powder when such an operation was performed several times.

For comparison, Table 1 also shows the operational results when conventional equipment as shown in Figure 3 was used and iron ore powder was introduced into the atmosphere without passing through the exhaust gas treatment duct.

Note that in the case of the conventional method, the powder temperature before the top blowing lance remains at room temperature, whereas in the case of the present invention method, it is preheated to 300 to 800°C.

Table 1 As is clear from the table, the method of this invention was able to significantly increase the supply rate of iron ore powder compared to the conventional method. That is, when the amount of carbonaceous material supplied as a heat source is the same, the amount of iron ore powder to be processed can be increased, and when one-way iron ore powder is processed, the amount of carbonaceous material used can be reduced.

In addition, in this invention method, since the iron ore powder is preheated and added to the furnace, the reduction of the iron ore progresses reliably in a short time. These are thought to be caused by unreacted iron ore in the slag) were not observed at all.

Furthermore, due to the heat exchange with the iron ore powder, the temperature of the exhaust gas was lowered by about 50°C compared to the conventional method, reducing the burden on the dust collector and making it easier to treat the exhaust gas.

Example 2 Using the equipment and lance described above, ordinary converter smelting was carried out in which quicklime powder was injected instead of iron ore.

The supply speed of oxygen gas is 15 Nm”7m in total for top and bottom blowing.
It was set to 1n. In addition, the charging amount of quicklime powder is 45% per ton of hot metal.
kg.

Table 2 shows the change from hot metal ([%C]″ = 4.5) to molten steel ([%C) = 0, after correcting the difference in Si concentration in hot metal.
．． 5) shows the amount of temperature rise.

For comparison, the table also includes experimental results obtained using the conventional method.

Table 2 In the above experiment, the decarburization bond was almost the same, and the oxidation calorific value of Si was corrected, so the difference in temperature rise (1T) was the difference in the sensible heat of the added quicklime powder.

In Example 2 above, the temperature increase of the quicklime powder was directly used to raise the blow-off temperature, but in actual furnace operation, the increased heat amount was used to increase the amount of added iron ore powder and increase the scrap ratio. It can also be used for compensation to improve the steel tapping yield.

(Effects of the Invention) Thus, according to the present invention, by effectively utilizing the thermal energy of exhaust gas, the energy used in metallurgical furnace operation can be significantly reduced. There are no restrictions, and exhaust gas treatment can also be facilitated.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of equipment suitable for carrying out the present invention, Fig. 2 is a diagram showing a nozzle structure at the tip of a lance which is also suitable for carrying out the invention, and Fig. 3 is a diagram of a conventional equipment. It is a schematic diagram of the equipment. 1... Top and bottom blowing converter 2... Furnace mouth 3... Dust collection hood 4...
・Exhaust gas treatment duct 5...Piping for pneumatic powder and granular material 6...Dispenser 7
... Top blowing lance ... Channel 9 for refining gas
... Powder flow path 10 ... Cooling water flow path Figure 3

Claims (1)

[Claims] 1. When adding powder and granules to a metallurgical furnace, a part of the piping for pneumatic powder and granules is installed in the exhaust gas flue of the metallurgical furnace, and the powder and granules are transferred by the sensible heat and combustion heat of the exhaust gas. A method for transporting powder and granules added to a metallurgical furnace, characterized by introducing the powder into the furnace after preheating.