JPS61127807A - Method for operating arc type electric furnace - Google Patents

Abstract

PURPOSE:To prevent almost perfectly the melt fracture of the wall of an arc type electric furnace by tilting the furnace while leaving unmelted scraps at the wall part to discharge a melt of scraps from the tap hole. CONSTITUTION:A melt 16 of scraps is formed at the core part of an arc type electric furnace 7, and electrode rods 11 are pulled out of the furnace 7 while unmelted scraps 15 are left at the wall part 13. The furnace 7 is then tilted to discharge the melt 16 into a ladel through the gap among the unmelted scraps 15, the tap hole and a spout.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is: - A scrap filling layer charged into an electric arc furnace and formed in the furnace is melted by arc heat, and this melt and blast furnace hot metal are combined. The present invention relates to a method of operating the electric arc furnace in the process of mixing and oxygen blowing in a converter, and particularly relates to a method of obtaining a melt without damaging the furnace wall of the electric arc furnace.

(Prior Art) The present applicant has previously disclosed in Japanese Patent Application No. 189732/1987 that in a method of blending scrap into blast furnace hot metal and injecting oxygen with KF, the present applicant has proposed a method in which scrap metal is blended with a high concentration of scrap metal and impurity elements are In this method, ordinary scrap, such as purchased scrap, is pre-carburized into a rectangular shape for producing high-quality negative steel, especially cold-rolled steel sheets, and then oxygen-blown in a rolling mill. Staranop bath intoxicant with dissolved C content of 3% or more (
Obtain simulated hot metal, conduct a component analysis of this scrap melt, adjust the blending lid of the scrap melt to the high f melt according to this analysis value, and mix it into the mixture of blast furnace hot metal and scrap melt. Quantity of impurity elements that are difficult to remove by bare metal blowing (tramp element concentration) is diluted to a value below that which can be used to manufacture steel sheets, and this mixture is subjected to acid cumulative blowing. This is a method for fabricating high-quality steel.

According to this method, since the tl+ scrap is pre-carburized and melted into pseudo F6 pig iron, it is possible to easily analyze the components, and the Anonymous r'iE
Is it easy to grasp this outcome and the quality of the steel that should be built? By determining the blending ratio with tJf hot metal, it is possible to stably produce high quality steel.

(2) Furthermore, in the converter, simulated hot metal, high F bath gauge, and scrap generated within the steelworks (scrap whose components are clearly known) are input as iron source raw materials, and the carbon-containing fuel is input into the converter as a total heat source. Therefore, the nitrogen content in the carbon-containing fuel does not enter the molten iron bath. Also, with this method, carbon in the simulated hot metal! A total of 3 or more islands. Therefore, carbon #i3%
The above can be ensured. As a result, the amount of silicon caps in the molten iron can be easily reduced to the desired one shift.

(3) Simulated molten cod retains M heat r for a sufficient period of time in the bath molten state and contains 3% or more of carbon, which serves as a heat source for raising the temperature of hot metal in the converter. It is possible to easily mix multiple scraps with momme J of 50y2 or more.

In this way, the scrap carburization melting process in the proposed method, which can be blended with the scrap that is said to be the purchasing group and can stably produce high-quality bath steel for use in copper casting, especially cold-rolled steel, is the well-known arc method. It can be carried out using an electric furnace.

Arc type electric furnace, e.g. raw material charging ~ melting ~ oxidation ~ slag removal ~
A general company that carries out the entire steelmaking process from reduction to tapping! ! An arc furnace for steel uses three-phase alternating current to generate an arc between the raw material charged into the furnace and an electrode, and uses the heat to melt all of the charged raw material.

In the steelmaking arc furnace in Jiraishorai, the resistance of the furnace wall in the vicinity of the electrodes is affected by the difference in the actance of each phase, the voltage of each phase, the unbalance of force, the arc current of each phase, and the electromagnetic force acting between them. The person has a tendency to be arrogant. In addition, scrap of the wave-toned raw material is put into an arc furnace, three electrodes are suspended from above, and an arc tl is generated between the scrap and the scrap by high power.
When the scraps are melted, the scraps closest to the three electrodes are dissolved first, and the scraps between the electrodes on the furnace wall remain as unexplored -2. The melting of scrap near the electrodes causes the inner wall of the furnace in that area to become hot, making it more susceptible to bath damage.

Moreover, in order to suppress damage to the furnace wall, in addition to electrical measures, a water-cooled box or cooling block is used as a support for the furnace wall.
Publication No. 13 states that when it is detected that the inner wall of the furnace in that area becomes high temperature due to the melting of scrap near the three electrodes, the furnace body is horizontally rotated 30' to the left or right, and the temperature of the three electrodes is increased. A method has been proposed in which unmelted scrap is placed nearby and all the charged scrap is melted in a short time without melting the inner wall of the furnace. Damage countermeasures require a furnace wall temperature history detection strategy as well as an F-shell rotation mechanism, which requires a total of 100,000 units.

Therefore, in the steelmaking arc r, if all of the charged scrap is not melted during the melting process and unmelted scrap remains on the fI hanging wall, when tapping due to the tilting of the electric furnace, the furnace wall Unmelted scrap remaining in the steel falls into the molten steel and melts, and the conventional components that have been carefully prepared fluctuate, making it impossible to obtain molten steel with the specified composition (specified steel type). In the converter steel manufacturing method, the scrap melting process, scrap melt, high f.
# The functions are divided into the furnace mixing process and the converter oxygen blowing process of the mixture. When tapping the metal by tilting the arc type electric furnace, unmelted scrap remaining on the furnace wall melts into the molten metal, and the process melts into the bath. Focusing on the fact that there is no problem even if the hot water composition fluctuates, we have completely changed the meaning of the furnace wall of the electric arc furnace used in the scrap melting process in the converter manufacturing process.
We have also invented a method of operating an electric arc furnace that can be prevented at low cost.

(Problems to be Solved by the Invention) The present invention is directed to an arc metallization process adopted in the scrap melting process of the 5F steelmaking method for refining hot metal made by mixing (combining) simulated iron and one-furnace pig iron. Completely eliminate the melting of the furnace wall of r.
The present invention also provides a method for operating an electric arc furnace that can be prevented at low cost.

(Means for solving all problems) The technical idea of the present invention is to protect the furnace wall by effectively utilizing all the scraps of the electric arc furnace K as a heat shield material to the furnace wall, and to prevent melting of the G3 pot. The gist of the present invention is to decompose the packed scrap layer formed inside the furnace after charging into an electric arc furnace using arc heat, and to decompose this melted material. In the method for operating the arc type electric furnace, which involves mixing 1IJf' hot metal and oxygen blowing with a rotary rotor, among the amount of scrap light in the arc type cage furnace r, F
The core scrap light layer was left as is without melting, and the r core scrap light horizontal layer W) was melted, leaving an unmelted scrap source layer on the furnace wall. Ku style'1
A method of operating an arc type electric furnace is provided, characterized in that the air furnace metal is tilted, and the scrap melt is tapped from the T-arc type electric furnace outlet.

(Example〕 The method of the present invention will be explained in detail below.

Figure 8-1 shows a partial cross-section and square diagram of a well-known electric arc furnace, that is, a three-phase AC arc furnace. One unit 3 in which engagement-2 is formed is fixed. Retaining teeth 4 formed in an arc shape
The furnace leg 5 is placed on the furnace stand 3 with the engaging teeth 2 and 4 held together, and one end of the furnace 11QI5 is supported by a tilting drive frame 6 that extends and contracts in the longitudinal direction. , f
The furnace body 7 mounted on the Jj&l 15 can be tilted.

An outlet 8 is provided in the furnace wall (furnace side) of the f' body 7, and an outlet gutter 9 is provided, and a number of r lids 10 are provided in the upper opening of the body 7. Three hanging plate electrode rods 11 are mounted on a tray and placed at equal intervals from each other in the central opening of the furnace lid 10.
is inserted into the r body 7. The furnace body 7 includes a steel T-bottom part 13 and a cylindrical furnace side part (furnace wall part) 1.
A ladle 014 consisting of 2 and 2 is used to receive bath water from the outlet gutter 9 of the furnace body 7.

In the three-phase or flow type arc r having the above configuration, the electrode rod 11 is pulled up by a device (not shown) explained in the method of the present invention, and is inserted into the ψ body 7 with the furnace lid 10 removed. Ash wood, for example, soil graphite with thorns, and charcoal wood 1-(
(not shown), and then, after disposing of the scraps in the r-body 7, several pieces of the furnace cover 102gs are placed in the gs-body 7 again.

After that, the electrode rod 11i is gradually pushed into the furnace body 7, and the electric power i is sent to the turtle @w11! 8 trains. -Ichigami Town-・-1
・An arc was generated between the 7-hi electrical power 11 and the scrap in 8, and the Sukurano 7-sword around the siege was melted. ? By lowering and raising the electrode rod 11 in accordance with the melting of the scrap around the IL sliding rod 11, the F wall scrap is left as it is without being disintegrated, and arc heat is transferred to the furnace wall of the furnace body 7. Blocker (
・Can the furnace core be scrapped while preventing damage to the furnace wall? Unmelted scrap 15 remains on the T wall of the furnace body 7 as shown in Figures 2 and 3. Complete core scrap melting.

The scrap melted by the arc heat flows down in the form of droplets, covering the soil graphite on the bottom of the furnace, and the bath water is prevented from penetrating into the soil graphite particle + a + gap due to its surface tension, and the soil graphite is Even though the ratio is small, the sword does not rise to the surface and always remains on the bottom of the furnace until the melting work of the r core is completed. And the contact between the soil graphite remaining on the bottom of the furnace and the scrap melt! As charcoal millet production progresses on the J1 stage, soil graphite is gradually consumed.

2 and 3. Remove the unmelted scrap left on the furnace wall by removing the electrode rod 11 from the furnace body 1, tilting the furnace body 7, and scraping the scrap carburized melt. 1
6, unmelted scrap 15-15 gap, outlet 8.
Molten metal is tapped through a tap trough 9 and received in a ladle 14.

Incidentally, when the furnace body is tilted, the unmelted scrap 15 on the furnace wall falls into the molten scrap W4 material 16 and is melted, and the composition and temperature of the bath water fluctuate. However, the molten metal received in the ladle 14 is The components are analyzed, and the blending ratio of scrap melt and blast furnace molten metal is adjusted according to the analysis area, and the mixture is removed by continuous blowing in the mixture of high f hot metal and scrap melt. Difficult filtering of impurity elements (Trump Element'mI
f) Since the mixture is diluted to below the T4 value that allows production of e-steel plate, and the mixture is oxygen-blown in a converter to form molten steel, it is completely out of the question.

Although the method of the present invention has been described above using an example using a three-phase AC type arc, it can also be carried out using an LA type arc T.

(Effects of the invention) As detailed above, according to the method of the present invention, melting of scrap by oxygen blowing in a converter is possible while almost completely preventing melting of the furnace wall of an electric arc furnace and without any capital investment. It is something that can be used to manufacture things.

[Brief explanation of drawings]

The drawings are all detailed explanations of the present invention (2), and Figure 1 is a partial cross-sectional front view of a three-phase AC arc furnace that implements the method of the present invention, and Figures 2 and 3 are diagrams showing the arc shown in Figure 1. FIG. 2 is a cross-sectional view and a vertical cross-sectional view illustrating the entire state of scrap melting in T. １・・・ ・基台２・ ・・ ・・・保合歯３ ・・・・・炉台４・・・・ ・保合歯５・・・・パＴ脚６・ ・・ ・ ・・傾動駆動Device 7... 2 bodies 8... ・Tailing port 9... ・Tapping gutter 10... Furnace cover 11... Electrode rod 12... ・Furnace bottom 13. ... Furnace body (furnace wall) 14 ... Ladle 15 ... Furnace wall unmelted scrap 16 ...
Furnace core scrap molten material application person Kura Nippon Steel Corporation ST diagram Figure 2

Claims (1)

[Claims] (1) The above-mentioned arc-type electric furnace is used in the process of melting the scrap filling layer charged into the arc-type electric furnace and formed inside the furnace using arc heat, mixing this melt with blast furnace hot metal, and oxygen blowing in the converter. In the method for operating the furnace, the scrap filling layer in the furnace wall of the scrap filling layer in the arc type electric furnace remains as it is without melting, and the scrap filling layer in the furnace core is melted and the scrap filling layer in the furnace wall is melted. 1. A method of operating an electric arc furnace, comprising tilting the electric arc furnace while leaving an unmelted scrap filling portion, and tapping the molten scrap from an outlet of the electric arc furnace.