JPS62297413A - Method and apparatus for refining molten metal - Google Patents

Abstract

PURPOSE:To improve the reaction efficiency by shifting as percolating refining agent and slag toward one direction and reverse direction by flow accompanied with rotating motion caused by a magnetic field of molten metal in a bending reaction vessel. CONSTITUTION:Rotating force is forced as acting the rotating magnetic field by a rotating magnetic field generator 5 in such as molten iron 3 held in the bending reaction vessel 2 (refractories). As a result, the rotating motion generated in the molten iron 3 is transmitted to the opposite side (left side in the attached drawing) of the apparatus 5 through the max. deep part corresponding to the bending part of the vessel 2, and whole molten iron is moved as rotating. Then, flux 4 for desulfurized agent is blown from the left side through an injection lance 6 together with a small quantity of carrier gas. The flux 4 is enclosed into the rotating motion of the molten iron and reacts in contact with the molten iron in the vessel 2, to execute the desulfurized reaction and to float up as slag 7. ?Then, the apparatus 5 is once stopped and at the time of acting the rotating magnetic field to the molten iron by the same apparatus 5' in the other side, the slag 7 is floated up on the molten iron at the apparatus 5' side while reacting in same manque, as described above. Such a process is executed one or more times, to refine.

Description

[Detailed description of the invention] 3. Detailed description of the invention (industrial application field) Advantageously promotes reaction with a refining agent when refining molten metal, such as carbon-containing molten iron, molten steel, stainless molten steel, etc. The results of research on new methods and mechanisms are proposed below.

(Prior art) Methods for dephosphorizing and desulfurizing carbon-containing molten iron (hereinafter referred to as molten pig iron) are as follows: ■ A lance is immersed in molten iron in a pig iron mixer or ladle, and a desulfurizing agent or dephosphorizing agent is applied. (blow-in) so-called hot metal pretreatment method; ■ A method in which a desulfurizing agent or dephosphorizing agent is injected together with refining oxygen gas in a converter with bottom-blowing tuyere; Methods such as injecting a pill have been used. These dephosphorization and desulfurization treatments are detailed in, for example, Tetsu to Hagane 71 (1985) p.394.

However, in these desulfurization and dephosphorization treatments, the reaction efficiency of the dephosphorization agent and desulfurization agent is generally low, and especially when attempting to melt ultra-low sulfur and low phosphorus steel, the above treatments are insufficient and transfer is difficult. Desulfurizing and dephosphorizing agents are added to the molten steel in the ladle tapped from the furnace, and in this case, a multi-step operation using a ladle refining device with a heating device is required.

(Problems to be Solved by the Invention) It is an object of this invention to advantageously improve the reaction efficiency in chemical reactions of molten metals, such as dephosphorization and desulfurization reactions of hot metal, and to reduce the amount of refining flux and processing time. This is the purpose of

The above objects of the invention can be effectively achieved by the procedures and mechanisms that are based on the matters described below.

As the main reaction part, molten metal is housed in a curved tube-shaped refractory reactor with upward flow channels on both sides, and while a refining agent is supplied to the bath surface of the molten metal from one of the openings, it is melted on the other side of the opening. A rotational force is forced on the metal bath to move the refining agent or slag through the molten metal bath to the other side of the opening, and then a rotational force is forced on the molten metal bath on one side of the opening for refining. A method for refining molten metal (first invention), characterized in that the step of moving the agent or slag through the flow in a reverse direction is carried out alternately at least once, during which refining is promoted by direct contact with the molten metal.

A molten metal refining device (second invention).

In the processing operation using the new molten metal refining apparatus schematically shown in FIG. While supplying flux 4 as a refining agent into the bath of molten metal 3 from one opening B1, a rotational force is forced to the bath of molten metal 3 at the other opening 1' side.

This rotational force is generated by a rotating magnetic field generator 5 disposed around the outer periphery of the container 2 on the opening 1' side.

Accompanied by this rotating magnetic field, a swirling flow is generated throughout the bath of molten metal 3, and the flux 4 of the refining agent or the slag that becomes a metamorphosis thereof is caught up in the flow and passes through the bath of molten metal 3 to the other opening. The metal flows through the water toward the bath surface on the 1' side, during which time it undergoes a sufficient contact reaction with the molten metal.

However, the slag 7 that floats after the reaction still has refining ability, and if it is brought into contact with the hot metal while stirring, the reaction efficiency will further increase. Therefore, after blowing in a certain amount of 7 lacs, the rotating magnetic field generator 5 is operated as described above and stopped, and then the rotating magnetic field generator 5' on the opening 1 side is activated. As shown in Figure (b), the slag 7 on the bath surface on the opening 1 side is drawn into the swirling swirling flow that occurs throughout the bath of molten metal 3, and moves through the bath surface on the opening 1 side again. .

By repeating the above-mentioned back and forth procedure at least once, the refining function of the flux can be utilized more completely and refining can be performed with high reaction efficiency.

Regarding this flow-through movement, the inventors previously obtained the following findings in a preliminary experiment using waterflies.

That is, as shown in Fig. 2(a), mercury m is placed in a curved pipe container bent in the shape of a ■ character, and a rotating magnetic field generator f surrounding one side of the curved pipe container is attached, whereby the mercury m A rotating magnetic field was applied to generate swirling flow, and water W was supplied from the oil side of the curved pipe container.

At this time, if sufficient rotational force is applied to mercury m, water IJ
As m rotates, a flow as shown by the arrow α in Fig. 2 is generated as a whole, and as a result, the water W supplied to the left side of the figure is engulfed by the flow of mercury m, and on the side where the rotating magnetic field generator f is attached. It was found that mercury m migrates like Wo towards the bath surface.

If a sufficient rotational flow is generated in the mercury m, all of the water W supplied from one end of the bent tube container will be absorbed by the mercury m generated in the bent tube container.
It was confirmed that the liquid was mixed in contact with the swirling flow of the pipe and transferred to the other end of the curved pipe container like a wo.

Next, a rotating magnetic field generator g attached to the other side of the container was used to apply a rotating magnetic field to generate swirling flow, and as a result, as shown in Figure 2, water W' on the surface of the bath of mercury m It was confirmed that all of the mercury m was brought into contact with the swirling flow of mercury m generated in the curved tube container, mixed together, and transferred to the other end of the curved tube container.

In this experiment, we used one liter of water, but we also tested liquids and powders of various specific gravities outside the water's edge, and found almost the same results as long as the specific gravity was lower than that of mercury.

Based on the above knowledge, the inventors conducted a refining experiment using a curved pipe vessel, and as a result, it was found that the reaction efficiency was even higher than that using a conventional chemical reaction vessel for molten metal, and the refining agent (the amount and processing time) It has been confirmed that it is possible to save on the amount of water used.Desulfurization treatment will be explained in detail below using an example.

(Function) Hot metal 3 was housed and held in the reaction vessel 2 shown in FIG. 1, and a rotating magnetic field was applied to the hot metal 3 by the rotating magnetic field generator 5 to force rotational force. As a result, the rotational motion generated in the bath of hot metal 3 is transmitted through the deepest part of the reaction vessel 2, which corresponds to the bending part, to the opposite side where the rotating/rotating magnetic field generating device 5 is not operated.
The entire hot metal moves in rotation.

At this time, the desulfurizing agent flux 4 is injected into the hot metal from the side where the rotating magnetic field generator 5 is not activated.
It was blown in with a smaller amount of carrier gas.

The flux 4 is drawn into the rotational movement of the hot metal 3, reacts while coming into contact with the hot metal in the reaction vessel 2 while causing a desulfurization reaction, and then floats up as slag 7.

Therefore, the rotating magnetic field generator 5 was temporarily stopped, and a rotating magnetic field was applied to the hot metal 3 by the rotating magnetic field generator 5' attached to the oil side. At this time, the slag 7 is drawn into the rotational movement of the hot metal 3 as shown in FIG. 1(b), and after reacting while contacting the hot metal in the reaction vessel 2 while causing a desulfurization reaction, the rotating magnetic field generator 5' It floats above the hot metal on the side.

According to this invention, the flux 4 is first drawn into the bath of the hot metal 3 by the rotation of the hot metal 3, and the flux 4 is sufficiently stirred in contact with the hot metal, and flows through the opening toward one side of the reaction vessel 2, thereby preventing desulfurization. The reaction rate increases.

In particular, even when an active flux such as CaF2 is used as a desulfurizing agent, the injected flux 4 gathers at the center of the rotational motion (this is because the flux does not generate an induced current due to the magnetic field, so no electromagnetic force acts on it). The center of the bath gathers under the difference in specific gravity between the hot metal 3 and the hot metal 3 without the rotational force generated by the rotating magnetic field, so when it comes into contact with the refractories that make up the reaction vessel 2, it reacts with the refractories and causes damage. I almost lost the opportunity to give.

Furthermore, the rotational movement of the hot metal 3 can be used to instantaneously entrain the flux 4 into the hot metal and sufficient contact can be created during the flow through, so that the process can be carried out in a short period of time.

By repeating the above procedure several times, the wave-dissipating function of the flux can be fully utilized and refining can be performed with high reaction efficiency and in a short time, making it possible to easily melt ultra-low sulfur steel. It is also possible to promote the reduction reaction by supplying a raw material mainly consisting of metal oxides such as iron ore into the hot metal.

Generally, the shape of the reaction vessel 2 may be any shape having a curved part such as a U-shaped tube or a V-shaped tube.

In the above explanation, desulfurization (refining) treatment was used, but
Of course, it is possible to perform refining according to the purpose by changing the refining agent. For example, in a dephosphorization 1+1 tank, a dephosphorization agent can be added at the beginning of the decarburization process of hot metal 3 (C: 3.3% or more). It is also possible to give a rotating flow to the hot metal 3 to improve the contact reaction rate with the dephosphorizing agent.

The refining agent referred to herein refers to an oxidizing refining agent or a reductive refining agent such as a dephosphorizing agent, a desulfurizing agent, a desiliconizing agent, etc., and is not limited to a state of a liquid solid alone or a mixture.

(Example) Implementation (Row 1 Rotating magnetic field generator '15 (r4?1) with an inner diameter of t4oomm and a height of 1000mm. The diameter of the different space is 1400mm and the height is 1000mm, and the magnetic field strength at the center of the space is A maximum of 600 Gauss) was made into a V-shaped tube quib with an outer diameter of 1300 mm and an inner diameter of 9 QQ mm made of a refractory material and an outer plate of non-responsive I raw material, and was placed in a curved tube-shaped reaction vessel 2 having a bent part with the diameter of the motherboard. On the other hand, it was installed as shown in Figure 1.

At this time, 16 tons of hot metal (carbon concentration 4.3%) at 1400°C was inserted into the reaction vessel, lance 6 was immersed in the iron bath, CaO-based flux was used as the desulfurization agent, and N was used as the carrier gas.
2 was used to blow the air.

The rotating magnetic field generator 5 is operated while a predetermined amount of desulfurization agent is injected, and after the flux is engulfed in the hot metal and floats as slag 7 on the side of the rotating magnetic field generator 5, the rotating magnetic field generator 5 is operated. stopped, and the rotating magnetic field generator 5 instead
' was applied. Slag 7 is rolled into the hot metal again,
It moved to the opening on the side of the rotating magnetic field generator 5. The floated slag 7' was stored in the container for a predetermined time and then periodically discharged from the gutter 9.

On the other hand, as a comparative experiment, the following experiment was conducted using the equipment shown in FIG.

A cylindrical container 8 having an outer diameter of 1300 mm and an inner diameter of 900 mm made of a refractory material and an outer plate made of a non-magnetic material was installed as in the example. 5.3 tons of hot metal (carbon concentration approximately 4.3%) at 1400°C was charged into the cylindrical container 8, and the lance 6' was immersed in the iron bath as in the example, and the same desulfurization agent and N2 were used as the carrier gas. I blew it.

FIG. 4 shows the relationship between the amount of desulfurizing agent injected and the hot metal components in Examples and Comparative Examples.

It can be seen that the amount of desulfurization agent required to desulfurize to the same %S in the example according to the present invention is about 4 kg/less compared to the comparative example.

Although this invention has been explained using desulfurization of hot metal as an example, it is of course applicable to dephosphorization of hot metal, desulfurization, and other chemical reactions of molten iron.
It is effective as a chemical reaction vessel for other molten metals.

(Effects of the Invention) As described above, in this invention, a rotating magnetic field is applied to the molten metal in the curved tube-shaped reaction vessel 2 which is opened upward at both ends to cause movement mainly in the rotational direction. By utilizing the flow in the hot metal that occurs, a higher chemical reaction rate can be achieved in chemical reactions such as desulfurization and dephosphorization of hot metal compared to conventional methods. Can be provided.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing an embodiment of this invention, Figure 2 is a sectional view showing a model experiment using mercury, Figure 3 is a sectional view showing a comparative example of this invention, and Figure 4 is a sectional view showing a comparative example of this invention. Ca
It is a figure showing the relationship between the basic unit of O-based desulfurization agent and (%S) in hot metal. 1... Opening 2... Reaction vessel 3... Hot metal 4... Flux 5... Rotating magnetic field generator 6... Injection lance 7... Slag 8... Reaction vessel 9... Fig. 3 Fig. 4 Degradation of scales: lQl bait <;, -n)

Claims (1)

[Scope of Claims] 1. Molten metal is stored in a curved tube-shaped reaction vessel consisting of upward flow channels on both sides as the main reaction part, and a refining agent is supplied to the bath surface of the molten metal from one of the openings. On the other side of the molten metal bath, force is applied to the molten metal bath to remove the refining agent or slag.
Alternating at least one step of moving the refining agent or slag through the molten metal bath to the other opening side, and then forcing the molten metal bath on one side of the opening to force a rotational force to move the refining agent or slag back through the bath. A method for refining molten metal, characterized in that the refining is accelerated by direct contact with the molten metal during this period. 2. A method for producing molten metal characterized in that the main reaction part is a curved tube-shaped reaction vessel with upward flow channels on both sides, and is equipped with at least one pair of rotating magnetic field generators arranged around the outer periphery of the reaction vessel. Refining equipment.