JPH02250912A - Method and apparatus for continuously desulfurizing molten iron - Google Patents

Abstract

PURPOSE:To effectively execute desulfurization in the molten iron at low cost by adding desulfurizing agent into the exposed molten iron passing through a molten iron trough at downstream side of a skimmer, rapidly causing to flow down into a reaction vessel, stirring and reacting the accompanied desulfurizing agent and the floating molten desulfurizing agent. CONSTITUTION:The molten iron 2 tapped from a blast furnace is introduced into the skimmer 6 and slag 4 floated with a skimmer damper 8 is separated into a slag trough 10. The molten iron 2 passing through the lower end of the damper 8 is guided to the molten metal trough 14 narrowly contracting flowing passage width W2 arranged on a weir, and the desulfurizing agent is added with a desulfurizing agent adding by device 20 and rapidly caused to flow down along an inclined wall 16 and dipped into bottom part of molten metal pool in the reaction vessel 18 and the accompanied desulfurizing agent and the floating molten desulfurizing agent 22A are stirred and reacted. Then, the inclined angle of the inclined wall 16 is made to 45 to 85 deg., and the width W2 of the molten iron trough 14 is made to 5 to 50% of the width W1 in the reaction vessel 8. By this method, without necessitating to use a wide space, the desulfurization of the molten iron 2 is effectively executed at a low cost.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method and apparatus for continuous desulfurization of hot metal, and in particular, to a method and apparatus for continuously desulfurizing hot metal, and in particular for effectively removing hot metal tapped from a blast furnace to a tap trough of a casthouse using a simple device. Concerning continuous desulfurization method and equipment, iron making,
Widely used in the steel manufacturing field.

[Conventional technology].

In order to reduce the load on converters and other equipment as much as possible during steelmaking, hot metal tapped from a blast furnace is commonly subjected to preliminary treatment in which it is desiliconized, desulfurized, and dephosphorized in a pig iron mixing car.

In these preliminary treatments of hot metal, the desiliconization and dephosphorization reactions are intensified reactions and exothermic reactions, whereas the desulfurization reactions are reduction reactions and endothermic reactions, so soda ash in the pig iron mixing car is Even with the injection of a desulfurizing agent such as lime, the desulfurization reaction in the mixed pig iron car is limited because the temperature of the hot metal is low and the desulfurization reaction is difficult to proceed.

For the above reasons, it goes without saying that it is most desirable to perform the desulfurization treatment during the process of flowing down the tap culvert, which is the highest temperature period immediately after the iron is tapped from the blast furnace.

From this point of view, many conventional techniques have been disclosed in which desulfurization treatment is performed immediately after the iron is tapped into the cast bed of a blast furnace. For example,
-33010, JP-A-51-105913, JP-A-52
-42411, JP-A-59-143010, etc. An overview of these conventional techniques will be explained.

(a) Japanese Patent Publication No. 50-33010 This invention divides a gutter for conveying molten metal into two parts, provides a head between them, adds a desulfurizing agent to the upstream gutter, and stirs the downstream gutter caused by the head difference. Injecting the desulfurizing agent into the stream and blowing compressed gas into the downstream gutter,
Either the unreacted desulfurizing agent is blown into the stirring flow to accelerate the desulfurizing reaction, or at the same time, a partition wall is provided near the outlet of the downstream gutter to prevent the unreacted desulfurizing agent from flowing out and to increase the desulfurizing agent's content. This is a method that attempts to use it effectively.

However, the present invention has many points that are not disclosed, and in particular, the degree of stirring and the degree of mixing of the desulfurizing agent by blowing are unclear, making it difficult to implement.

(b) JP-A-51-105913 This invention provides continuous eyebrows that are provided with an inlet at one end and an outlet at the other end, and whose horizontal cross-sectional shape is circular and arranged in a row with a slight overlap. A rotating shaft is provided at the center of each single circular portion of the shaped processing tank, and a stirring mechanism having a plurality of stirring rods fixed to the rotating shaft via an arm is provided, and the direction of rotation of each of the rotating shafts is controlled. This is a continuous desulfurization method for molten metal in which desulfurization is performed in the same direction and with the upper end of the stirring rod always positioned below the static surface of the molten metal in a processing tank.

This invention seems to have a stirring effect, but running costs are thought to be relatively high due to wear and tear on the refractories.

(Q) JP-A No. 52-42411 This invention is a method of continuously pouring hot metal from a tap runner or a hot metal ladle into a desulfurization tank having a gas-injected porous plug for stirring hot metal at the bottom and a heating electrode. This continuous desulfurization method for hot metal is characterized by performing electric arc heating while stirring and using a mixture of blast furnace slag and fluorite or CaO-based synthetic slag as a desulfurization agent.

In this method, the molten pig iron is heated with a heating electrode, and inert gas is injected through a porous plug at the bottom for stirring, so the reaction efficiency is expected to increase, but the equipment cost is high and the There are problems with space, etc., and it is thought that the cost will be high.

(d) JP-A-59-143010 This invention divides the hot metal that is continuously flowing down in the hot metal gutter in the middle of the flow system of the hot metal, and creates a distributed flow with a head difference in the downstream flow system. A means for conveying powder and granular additives for pre-treatment of the hot metal into an entrained flow region generated on the surface of the hot metal in the downstream flow system by means of conveying high-speed airflow to the flow area generated on the surface of the hot metal in the downstream flow system accompanying this dispersed fall flow. This is a method for continuous preliminary treatment of hot metal, which consists of charging the hot metal at an accelerated rate by means of a jet.

This invention also seems to be able to desulfurize at a relatively low cost because the hot metal is divided into streams and the hot metal is stirred using a head, and the pneumatic desulfurization agent is jetted into this stirring flow, but it is not suitable for blast furnace casthouses. There is a problem in that a large space is required for dividing the flow.

[Problem to be solved by the invention]

An object of the present invention is to solve the problems of the prior art related to a method and apparatus for continuous desulfurization of hot metal, and in particular, to eliminate the need for a large space during the flow of high-temperature hot metal tapped from a blast furnace through a tap flute, and to reduce costs. The object of the present invention is to provide an effective method and apparatus that can desulfurize at low cost.

[Means to solve the problem]

The gist of the continuous hot metal desulfurization method according to the present invention is as follows.

That is, in a hot metal desulfurization method that desulfurizes hot metal by adding a desulfurization agent to the hot metal tapped from a blast furnace to a casthouse, there is a step of adding a desulfurization agent to bare hot metal passing through a hot metal trough downstream of the skinmer of the casthouse. , the step of causing the desulfurizing agent-accompanied hot metal that has passed through the hot metal trough to rapidly flow down through an inclined wall and introducing it into the reaction tank; and making the rapidly flowing hot metal sink to the bottom of the reaction tank to remove the desulfurizing agent and the desulfurizing agent. This is a method for continuous desulfurization of hot metal, characterized by comprising a step of stirring and reacting a molten desulfurization agent floating in the upper part of a reaction tank.

Next, the gist of the continuous hot metal desulfurization apparatus according to the present invention used to carry out the above continuous desulfurization method is as follows.

That is, in a continuous hot metal desulfurization device that desulfurizes hot metal tapped from a blast furnace to a cast bed by adding a desulfurizing agent, there is a hot metal trough provided downstream of a skimmer in the cast bed, and a hot metal trough that passes through the hot metal trough. a desulfurizing agent addition device for adding a desulfurizing agent to hot metal; a sloped wall for rapidly flowing down the desulfurizing agent-accompanied hot metal that has passed through the hot metal sluice; This continuous hot metal desulfurization apparatus is characterized by comprising a reaction tank in which the desulfurization agent and the hot metal are caused to react with each other by stirring.

Embodiments of the present invention will be described with reference to FIGS. 1A and 2B. 1(A), 2(B) and 2 show a device according to the invention, FIG. 1(A) being a plan view and FIGS. 1(B) and 2 being a sectional view.

Hot metal 2 tapped from the blast furnace flows down the tap trough together with slag 4 and reaches the skinmer 6, where it is blocked by the skinmer damper 8, and the slag 4 floating on the surface is separated into the slag trough 10 and treated as slag separately. sent to the process. The hot metal 2 that has passed through the lower end of the skimmer damper 8 is transferred to the skimmer 6.
The hot metal is temporarily stored by the weir 12 on the outlet side of the hot metal, but is guided by the sluice 14 provided on the weir 12, quickly flows down the inclined wall 16, and is introduced into the reaction tank 18.

The hot metal trough 14 according to the present invention has a tapping rate (t/m) from the blast furnace.
in), the channel width W2 can be adjusted. That is, the central part of the hot metal gutter 14 is the deepest and narrowest, but the channel width W2 gradually increases in a stepwise manner as it approaches the outer side of the gutter.

A desulfurizing agent addition device 20 is provided above the hot metal 4ii14, and adds a desulfurizing agent 22 onto the bare hot metal 2 passing through the hot metal trough 14. The reason why the channel width W2 is narrowed as shown in FIG. 1 (A) when the hot metal 2 coming out of the skinmer 6 is passed through the hot metal gutter 14 is because the desulfurizing agent addition bag is needed for the wide bare surface of the hot metal! ! This is because the addition of the desulfurizing agent 22 by i20 becomes uneven, and the purpose is to narrow the bare surface of the hot metal so that it can be added uniformly.

After passing through the hot metal trough 14 , the hot metal 2 to which the desulfurizing agent 22 has been added rapidly flows down along the inclined wall 16 that forms the inner surface of the entrance side of the reaction tank 18 . The hot metal 2 accompanied by the desulfurization agent 22 that has rapidly flowed down is deposited at the bottom of the hot metal pool in the reaction tank 18 as shown in Fig. 1 (B
) and as shown by curve C in FIG. 2, it penetrates and generates stirring flow.

In the present invention, in order to cause the hot metal 2 that has rapidly flowed down along the inclined wall 16 to sink to the bottom of the reaction tank 18 and generate effective stirring flow, the width W of the reaction tank 18 and the hot metal gutter 14 are
In addition to regulating the relationship between the flow path width W2 and the inclination angle α of the inclined wall 16.

This regulation is the result of the inventors' water model experiments and theoretical numerical calculations.

That is, the width W of the reaction tank 18 and the flow path of the hot metal gutter 14 @w
Between z and W, /W = 0.05 to 0.5 (1
) is regulated so that the following relational expression holds true. In other words, in the middle stage of tapping when the blast furnace tapping rate (t/5in) is high,
The flow path width W2 of the hot metal sluice 14 is set to 50% of the width W of the reaction tank, and at the end of tapping, W2 is set to 5% of the W width, and the width is increased from 5 to 50%.
The inclined wall 16 is adjusted according to the tapping speed within the range of
The purpose is to optimize the flow velocity of the hot metal 2 flowing down along. If it is outside this range, the good stirring flow that is the objective of the present invention cannot be obtained in the reaction tank 18, and the desulfurization agent 22 and the hot metal 2
The contact time with the product becomes shorter and a good desulfurization reaction cannot be obtained.

Next, in the present invention, the inclination angle α of the inclined wall 16 is set to 45 to 8.
It was limited to a range of 5 degrees. This is because when the inclination angle α of the inclined wall 16 is less than 45 degrees, the potential energy of the hot metal 2 is greatly reduced, and after the inclined wall 16 is introduced with the desulfurizing agent 22, If sufficient contact cannot be guaranteed, and if the inclination angle α of the inclined wall 16 is 85
If the temperature is exceeded, when the hot metal 2 falls into the reaction tank 18, an upward flow is generated due to the entrainment of air.
This is because the flow of the hot metal 2 does not occur in the bottom region of the hot metal 8, and the desulfurization agent 22 is not dragged into the hot metal 2 and the contact time thereof is not extended. For the above reason, the inclination angle α of the inclined wall 16 is limited to a range of 45 degrees to 85 degrees.

The type of desulfurizing agent 22 is not particularly limited in the present invention, but the purpose of the present invention is to desulfurize easily and effectively at low cost.

Cheap CaO-based desulfurization agents are preferred, such as quicklime CaO
-Limestone CaC0, mixture of 50% each, quicklime CaO-
A mixture of 50% each of calcium carbide and CaC2 is suitable. The method of adding the desulfurizing agent 22 may be by directly spraying it on the surface of the bare hot metal 2, or by blowing the desulfurizing agent 22 into air through a lance.

(Function) In the present invention, the relationship defined by equation (1) above is established between the flow path W2 of the hot metal trough 14 and the width Wi of the reaction tank 18 in accordance with the tapping rate (t/min) of the blast furnace. Since the slope angle α of the slope wall 16 is limited to 45 to 85 degrees,
The hot metal 2 accompanied by the desulfurization agent 22 flowing down the inclined wall 16 has an appropriate potential energy and is inclined! ! 16, but in the middle of the flow, in part A of the reaction tank 18, the desulfurization agent 22A, which has been turned into molten slag and floating on the hot metal 2 temporarily stored in the reaction tank 18, is also drawn in and reacted. Tank 18
The hot metal sinks into the bottom of the hot metal pool 2A and generates a stirring flow as shown by curve C in FIGS. 1(B) and 2. When passing through the molten desulfurizing agent 22A rolled up in the above-mentioned part A and the hot metal gutter 14, the accompanying desulfurizing agent 2 newly added
2 floats to the surface near point B at the bottom of the reaction tank 18 due to the difference in specific gravity, but only the hot metal 2 retains the potential energy due to the head flow, and due to the addition of inertia, C in the hot metal pool 2A in the reaction tank 18. Since the agitating flow as shown by the curve is generated and the slagged molten desulfurizing agent 22A floating on the surface of the reaction tank 18 is also involved, the desulfurizing agent 22 stays in the reaction tank 18 for a long time and does not mix with the hot metal 2. There are many contact opportunities, the desulfurization reaction is significantly promoted, and the reaction efficiency is improved.

〔Effect of the invention〕

The present invention provides a hot metal trough whose channel width can be adjusted in accordance with the tapping speed of the blast furnace in the dam downstream of the skinmer of the blast furnace casthouse, and an inclination angle of 45 to 85 degrees downstream of the molten metal trough. A reaction tank is provided with a sloped wall having a slanted wall, and the sloped wall is the inside surface of the inlet side, and a desulfurization agent is added to the hot metal passing through the hot metal trough, and the hot metal accompanied by the desulfurization agent is caused to rapidly flow down along the sloped wall. ,
By using the potential energy generated by this head to generate stirring flow of hot metal at the bottom of one reaction tank, we have adopted a configuration that allows the desulfurization agent to stay in the reaction tank for a long time and increases the chances of contact with the hot metal. The following effects were achieved.

(a) Since the present invention desulfurizes high-temperature hot metal immediately after being tapped from a blast furnace, the desulfurization efficiency is higher than desulfurization in the pig iron mixing car.

(b) In the present invention, since the desulfurizing agent is added to the hot metal passing through the hot metal trough having a relatively narrow channel width downstream of the skimmer, it can be added uniformly.

(c) By limiting the flow path width of the hot metal trough and properly regulating the slope angle of the sloped wall, it is possible to impart appropriate potential energy to the hot metal accompanied by the desulfurization agent, and the flow rate along the sloped wall is increased. The rapid flow creates stirring flow in the hot metal introduced into the reaction tank, which extends the contact time between the desulfurization agent and the hot metal, and also brings unreacted desulfurization agent into contact with the hot metal, increasing desulfurization efficiency. I was able to improve it significantly.

(d) Since the device according to the present invention is extremely simple, the equipment cost is low, it can be easily installed in the limited space of the blast furnace cast bed, and the operating cost is also relatively low. Desulfurization is now possible.

[Brief explanation of drawings]

Figures 1 (A) and (B) show a method and apparatus for continuous desulfurization of hot metal according to the present invention, (A) is a plan view, (B) is a sectional view, and Figure 2 is a method for continuous desulfurization of hot metal according to the present invention. FIG.

Claims (4)

[Claims] (1) In a hot metal desulfurization method in which a desulfurizing agent is added to desulfurizing molten iron tapped from a blast furnace to a casthouse, a step of adding a desulfurizing agent to bare hot metal passing through a hot metal trough downstream of a skinmer in the casthouse. and a step of causing the desulfurizing agent-accompanied hot metal that has passed through the hot metal trough to rapidly flow down through an inclined wall and introducing it into a reaction tank, and causing the rapidly flowing hot metal to sink to the bottom of the reaction tank to absorb the desulfurizing agent and the accompanying desulfurizing agent. A method for continuous desulfurization of hot metal, comprising the step of stirring and reacting the molten desulfurization agent floating in the upper part of the reaction tank. (2) In a continuous hot metal desulfurization device that desulfurizes hot metal by adding a desulfurizing agent to the hot metal tapped from the blast furnace to the cast bed, the hot metal passes through a hot metal gutter provided downstream of the skimmer of the cast bed and the hot metal gutter. A desulfurization agent addition device that adds a desulfurization agent to bare hot metal;
A reaction tank having an inclined wall for causing the desulfurizing agent-accompanied hot metal that has passed through the hot metal gutter to rapidly flow down, and a reaction tank in which the introduced hot metal is allowed to submerge into the bottom of the inlet side using the inclined wall as the inner surface of the inlet side, and the desulfurizing agent and the hot metal are stirred and reacted. A continuous desulfurization device for hot metal, comprising: (3) Claim (2), wherein the flow path width of the molten iron gutter through which the bare molten iron passes can be adjusted to 5 to 50% of the width of the reaction tank in accordance with the tapping rate (t/min) of the blast furnace. Continuous desulfurization equipment for hot metal as described. (4) The continuous hot metal desulfurization apparatus according to claim 2, wherein the inclined wall has an inclination angle of 45 to 85 degrees.