JP2002212619A - Method for returning raw material in converter operation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a useful operational method in a converter, particularly, in a situation of an energy saving when a non-normal state is developed in a refining process or a casting process succeeded to this process. SOLUTION: When the refining is performed in the converter after charging molten iron from a blast furnace into the converter, molten steel obtained by refining in the converter, based on the development of the non-normal state in the refining process or the casting process succeeded to the refining process, is charged as the molten state together with the molten iron into the converter and used as the main raw material to perform the refining.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation of refining hot metal from a blast furnace in a converter, and more particularly to an operation of a converter when an unsteady state occurs in the refining process or a subsequent casting process. It is.

[0002]

2. Description of the Related Art In a steelmaking process, hot metal poured from a blast furnace is received in a hot metal charging pot or a mixed iron wheel and, if necessary, subjected to a preliminary treatment in the hot metal charging pot or a mixed iron wheel before being converted into a converter. And refining in the converter. Molten steel obtained through this steelmaking process is cast into a steel material such as a slab or a bloom in a casting process represented by, for example, continuous casting.

[0003] Here, a steel material produced by casting must have a component composition corresponding to its use, product specifications, etc., but in a refining process including pretreatment in a hot metal charging pot or a mixed iron wheel. , Unsteady state, that is, deviation from the setting range of various refining conditions and trouble of steel making equipment, etc.
Outside the steady state of operation, the composition of the molten steel as a starting material of the steel material after refining may deviate from a desired range.

[0004]

In such a case, the components and the temperature may be adjusted by re-blowing (re-blowing) in the converter. It is synchronized with the casting of the process (continuous casting), and if reblown, the casting of the subsequent process must be interrupted; (ii)
Once tapping into the steel ladle, the heat dissipation is so intense that even if the molten steel whose temperature has dropped significantly is returned to the converter, the molten steel after blowing will not have enough thermal margin during reblowning, making it difficult to reblown. (Iii) Even just before tapping, as in (ii) above, there is no thermal margin at the time of re-blowing and re-blowing becomes difficult. Without re-blowing, after the molten steel of the charge is output to the molten steel ladle, it is directed to the ingot making process, and poured into the casting mold for waste steel ingot, which is always prepared in the ingot making process, It was held as a steel ingot (scrap). Thereafter, the use of this steel ingot as a raw material requires re-melting, which causes a problem of large energy loss.

[0005] Incidentally, it is conceivable that the product is poured into a mold for obtaining a product in the ingot making process. However, in order to obtain the product as a product, a downward pouring ingot making method is mainstream. It is not organized and cannot be implemented.

[0006] In the casting process following the refining process,
In the unsteady state, that is, when casting becomes impossible due to trouble in the casting equipment, molten steel cannot be supplied to the casting process, so the molten steel after refining is also poured into a waste steel ingot casting mold in the same manner as above. Will be reused as scrap.

Accordingly, an object of the present invention is to propose an advantageous method of operating a converter when an unsteady state occurs in a refining process or a subsequent casting process, particularly from the standpoint of energy saving.

[0008]

That is, the gist of the present invention is as follows. (1) When hot metal from a blast furnace is charged into a converter and refined in this converter, refining is performed in the converter in consideration of the occurrence of an unsteady state in the refining process or the casting process following this refining process. A method for returning a raw material in a converter operation, wherein the molten steel obtained as described above is charged into a converter together with hot metal in a molten state and reused as a main raw material to perform new refining.

(2) The method of (1) above, wherein the molten steel obtained by refining in the converter is divided into a plurality of charges and charged into the converter.

(3) In the above (1) or (2), the molten steel obtained by refining in the converter is temporarily received in a hot metal charging pot, and charged into the converter from the charging pot. Method of returning raw materials in converter operation.

(4) In the above (1) or (2), the molten steel obtained by refining in the converter is once received in a mixed iron wheel, and charged into the converter together with the molten iron. Return method.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the method of the present invention will be described.
This will be described in detail with reference to the drawings. First, a typical example of a steelmaking process to which the method of the present invention is applied is shown in FIG. In the illustrated steelmaking process, hot metal 2 tapped from a blast furnace 1 is received in a hot metal charging pot 3 or a mixed iron wheel 4 and subjected to a pretreatment in the hot metal charging pot 3 or the mixed iron wheel 4 as necessary. The converter 5 is charged and refined in the converter 5 to produce molten steel. Molten steel obtained through this steelmaking process is subjected to a casting process represented by, for example, continuous casting, and is cast into a steel material such as a slab or a bloom.

[0013] Here, when the various refining conditions deviate from the set ranges, or troubles occur in the steel making equipment, or the like, and the operation becomes unsteady, the composition of the molten steel after the refining deviates from a desired range. . Further, in the casting process following the refining process, in an unsteady state where casting becomes impossible due to a trouble in the casting equipment, it becomes impossible to supply molten steel to the casting process.

That is, the molten steel obtained by the refining that has proceeded under the unsteady state is returned to the converter 5 again in the molten state without being solidified as before, and is used as the main raw material in the refining of the next charge. I do.

Next, FIG. 2 shows the handling of molten steel when returning to the converter again in the molten state. In this figure, 5 is a converter, 4 is a topped car, 3 is a hot metal pot, and 7 is a molten steel pot, as in FIG. Then, after tapping or immediately before tapping, molten steel that cannot be cast in the subsequent continuous casting step, or molten steel that cannot be cast in the continuous casting step, is reused in a molten state as follows. .

That is, the molten steel is once tapped into the molten steel pot 7 through the tapping port 5A of the converter 5, but when the tapped molten steel cannot be used for casting, the present invention provides: The molten steel is divided and charged into the hot metal ladles 3a and 3b (routes 6B and 6C in the figure). The molten steel and the hot metal from the torpedo car 4 or the blast furnace are received and transported by the hot metal ladle (not shown). And put it into the converter 5. Fig. 2 shows a topped car
Hot metal transported by 4A is taken out to hot metal ladle 3C (Route 6
D) Then, the hot metal in the hot metal pot 3C is
Pour the molten steel contained in the furnace (Routes 6E and 6F), and use the molten metal in which the molten steel and molten metal in the hot metal ladles 3A and 3B are mixed as the main raw material for one charge in the converter operation (Route 6G, H).

Conversely, the molten steel and the hot metal can be poured by putting the hot metal in the hot metal pots 3A and 3B and pouring the molten steel from the hot metal pot 7, respectively. Since the hot metal is added to the molten steel that has been blown by the above operation, the amount of C in the hot metal is particularly high and C can be used as a heat source during blowing, so that there is a thermal margin for the converter operation. Generated and can be blown.

By the way, when only the molten steel pot and the hot metal pot are used as described above, the heat dissipation of the stored molten metal progresses and the temperature drops sharply, so that it is difficult to wait for a long time in this state. The handling method imposes a restriction that it can be used only as the main raw material during converter blowing, which is relatively close to tapping. In the present invention, in order to solve the above problem, molten steel is dispensed from the molten steel pot 7 to the torpedo car 4B.
(Route 6I) or by temporarily dispensing to the hot metal pot 3 and injecting it into the torpedo car 4B (Route 6J), it is to be held in the torpedo car 4B. In this case, the heat dissipation is extremely low as compared with a molten steel pot or a hot metal pot, which is effective for holding for a long time. Further, the mixture may be injected into the hot metal in the torpedo car and maintained in a mixed state.

Next, the molten steel or the mixed molten metal of the molten steel and the hot metal held in the torpedo car 4B is discharged to the hot metal ladle 3C (route 6K) or mixed with the hot metal of another toped car 4A (route 6D). It is only necessary to charge the converter as the main raw material (route 6L). Since the hot metal is also added at this time, particularly high C in the hot metal can be used as a heat source, so that there is a thermal margin in the converter operation and there is no hindrance to the converter blowing.

In FIG. 2, the molten steel to be reused as the main raw material is divided into two charges. However, by further dividing the molten steel into a plurality of charges, the molten steel contains a special alloy component. In such a case, there is also an advantage that the concentration can be reduced and used.

[0021]

EXAMPLE The molten steel (heat size of 180 tons) obtained by refining according to the conditions shown in FIG. 1 was sampled after tapping from the converter, and its component composition was investigated. Thus, the P content exceeded the upper limit with respect to the target component composition. Therefore,
After tapping, the molten steel split into two (90 tons) was combined with the hot metal and returned to the converter. After that, in the converter, refining was performed as usual. We were able to.

[0022]

[Table 1]

[0023]

According to the present invention, when an unsteady state occurs in a refining process or a subsequent casting process, molten steel obtained by refining is recharged to a converter in a molten state and the main raw material is removed. Therefore, it is possible to utilize the unnecessary molten steel while minimizing the heat loss during the operation of the converter.

[Brief description of the drawings]

FIG. 1 is a diagram showing a steel making process.

FIG. 2 is a diagram illustrating a method of the present invention.

[Explanation of symbols]

 Reference Signs List 1 blast furnace 2 hot metal 3 hot metal charging pot 4 mixed iron wheel 5 converter 6 molten steel

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Akihiro Aoyagi 1-chome, Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama Pref. 1-chome (without address) Kawasaki Steel Corporation Mizushima Works (72) Inventor Hiroshi Nomura 1-chome, Mizushima-Kawasaki-dori Kurashiki City, Okayama Prefecture (without address) Kawasaki Steel Corporation Mizushima Works F-term (reference) 4K002 AB01 AB10

Claims (4)

[Claims] When charging molten iron from a blast furnace into a converter and performing refining in the converter, taking into account the occurrence of an unsteady state in the refining step or a casting step subsequent to the refining step.
A method of returning raw materials in a converter operation, wherein molten steel obtained by refining in a converter is charged into a converter together with hot metal in a molten state and reused as a main raw material to perform new refining. 2. The method according to claim 1, wherein the molten steel obtained by refining in the converter is divided into a plurality of charges and charged into the converter. 3. A converter operation according to claim 1, wherein the molten steel obtained by refining in the converter is once received in a hot metal charging pot and charged into the converter from the charging pot. Raw material return method. 4. The method according to claim 1 or 2, wherein the molten steel obtained by refining in the converter is once received by a mixed iron wheel and charged into the converter together with the molten iron.