JPS5822315A - Refining process for steel by blowing co-gas - Google Patents

Abstract

PURPOSE:To achieve economical refining of steel without denitration-treatment by following method in which CO gas generated in the maximum decarburization period is directly drawn out from the inner mid portion of an oxygen converter, and is brown into the molten steel bath from the converter-bottom. CONSTITUTION:At the muximum decarburization period of an oxygen refining furnace such as a converter 1, generated CO gas is directly drawn out by using a drawing lance 6 and is accumulated in a holder 8. The nitrogen content in the atomophere in a converter 1 is below 1% in said maximum decarburization period, therefore the generated gas is almost pure CO gas. This pure CO gas is brown into the molten steel bath from the converter-bottom by way of a regulator 9 for controlling flow amount of gas. Accordingly, pure CO gas is directly brown into the steel bath without denitration treatment by this process.

Description

[Detailed description of the invention] The present invention is an oxygen steelmaking furnace in which C is removed from the bottom of the furnace.

Regarding the refining method in which gas is injected and the steel bath is stirred, there is a method in which the CO gas generated in the furnace is used as the CO gas used in the refining process (as explained by Niseki).

In an oxygen steelmaking furnace, during or after acid blowing, 02 gas, Ar gas, CO gas, CO□Ganu, etc. are injected from the bottom of the furnace to stir the steel bath and promote the refining process. Widely implemented.

When C2 gas is used, a portion of it is taken out from the gas holder of the earth blowing #cable, but when other gases are used (usually all gases are supplied from other sources).

JP-A-55-158211 has already proposed a self-supply type to solve this problem. According to this proposal, the gas generated from the furnace mouth of an oxygen steelmaking furnace is stored in a gas holder, and a part of the gas in this gas holder is taken out. Three systems are shown: (3) Co2 is injected from the bottom of the furnace.

However, as shown in this proposal, the gas stored in the gas holder contains N2 gas of 1% or less per $20VO, and therefore, the above (1) and (2)
), it cannot be applied to steel types that do not want to contain nitrogen, and in fact, as shown in case (3), CO gas or C○2 gas (if two-pronged N and TI However, in order to perform the de-N treatment, a special de-N
It has the disadvantage of requiring additional equipment.

The present invention has been made in view of the above points, and it is possible to extract gas generated from deep inside the furnace at the peak of decarburization in a steel making furnace.
Therefore, by injecting this pure CO gas from the bottom of the furnace into the steel bath, taking into consideration the fact that two-line CO gas can be obtained, there is no need for de-N treatment at all, and the above drawbacks have been solved. It is something.

FIG. 1 shows an example of an apparatus for carrying out the present invention. In the figure, 1 is a converter, 2 is a top-blown oxygen lance, 6 is a steel bath, 4 is a bottom gas blowing device, and 5 is a waste gas recovery hood. 6 is a pure CO gas suction lance in the present invention, and a suction device 7 is provided in the piping system. A holder 8 and a flow rate adjusting device 9 are respectively provided to connect the two furnace bottom gas blowing devices 4C.

Therefore, during the slow decarbonization period at the beginning of blowing and the end of carbon removal at the end of blowing, the furnace atmosphere (:) contains 15% to 40% N2, but at the peak of the carbon removal reaction, Substantially N2 in the furnace
is less than 1%.

In the present invention, the gas generated in the furnace is recovered using a suction lance during the peak period of this decarbonization reaction, stored in its holder, and supplied to the gas blowing device at the bottom of the furnace to stir the steel bath. It is something.

Example ta) F container; 1oot (bJ Bathing component C; 4.5% S1; 0-44% Mn: 0*51% P: 0.110% S; 0.024% N 948 PPm +C1 top Amount of blowing acid: 20000 Ntp?/'Hr(
(11 Recovery time of gas generated in the furnace: 3 minutes to 10 minutes after blowing N2 concentration in the recovered gas: 0.3% + fl Hearth bottom gas injection amount: 100ONcrVHr
+ End point component and temperature [0) 0.12% Si; tr % Mn; 0.15% P; 0.011% s; 0.020% N; 12 PPm Temperature; For example, high-purity CO gas can be obtained directly from the converter internal force, without the need for denitrification treatment.
It can be directly blown into the steel bath from the bottom of the furnace, and can be carried out economically.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an apparatus for carrying out the entire method of the present invention. 6; CO gas suction lance 7; Suction device 8; CO2 gas holder 9; Flow rate adjustment device

Claims (1)

[Claims] A method for refining steel by CO gas injection, characterized in that CO gas generated during the peak period of decarburization reaction in an acid plasma steelmaking furnace is directly recovered from the inside of the furnace using a suction lance and injected into a steel bath from the bottom of the furnace.