JPS60184614A - Method for desiliconizing molten iron - Google Patents

Abstract

PURPOSE:To perform surely desired desiliconization in a blast furnace hearth so as to deal with desiliconization and dephosphorization of a large amt. of molten iron by adding respectively desiliconizing agents to the molten iron between the tap hole on the tapping spout and skimmer of the blast furnace and between the skimmer and torpede to effect desiliconization in two stages. CONSTITUTION:The molten iron 8 discharged from a tap hole 2 of a blast furnace 1 is separated to the molten iron 8 and slag 8-2 by a skimmer 4 provided in a tapping spout 3. The molten iron 8 is fed on a molten iron spout 5 on the down stream of the skimmer 4 to a torpedo car 7. A desiliconizing agent is added to the molten iron in the spout 3 from the hole 2 to the skimmer 4 preferably at a point near the hole 2. A desiliconizing agent 9-2 is added to the molten iron 8 separated of blast furnace slag and desiliconizing slag in the skimmer 4 after the primary desiliconization prior to falling into a torpedo car 7 to execute secondary desiliconization. The reduction of (Si) in the high Si-content molten iron 8 tapped from the furnace 1 to <=0.15% required for dephosphorization of the molten iron in the blast furnace hearth is made substantially possible by such two-stages of the desiliconization treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for desiliconizing hot metal tapped from a blast furnace, in which desiliconization of hot metal is efficiently carried out in a tap sluice.

Conventional technology and its problems One of the hot metal J''-preparation treatment methods that has recently been widely used is the trough desiliconization method, which desiliconizes hot metal by introducing a desiliconizing agent into the tap trough of a blast furnace. For example, as known from Japanese Patent Publication No. 58-56723, a desiliconizing agent is added to the hot metal tapped from the taphole of a blast furnace, and the natural mixing of the hot metal as it flows is utilized to remove the molten metal. A method is known in which the silicon contained in the gutter is removed by acidification.In addition, various methods have been used for this type of gutter desiliconization method, but all of the conventional gutter desiliconization methods involve using hot metal and hot metal. A desiliconizing agent is added downstream of the skinmer that separates the slag.This is because the desiliconizing efficiency is higher after slag separation.However, adding a desiliconizing agent only downstream of the skinmer causes the following problems. There is.

In other words, it is not possible to cope with fluctuations in tap iron (St). For example, if the average tap iron (St) is 9.45% and the target after treatment (Si) is 0.25%, if the iron tap [Si] becomes 0.60% due to fluctuations in blast furnace conditions, the (S
() It is difficult to achieve 0.25%. Furthermore, when hot metal dephosphorization is performed in the next step, it is desirable that [S1] after the treatment be as low as possible, and [Sl]≦0.15% is required. However, it is difficult to stably achieve this level by desiliconization treatment only downstream of the skinmer.

Conventionally, as a countermeasure against these problems, adjustment has been carried out using torpedo desiliconization, etc., but this is not suitable for large-scale processing because it increases the number of steps and processing time.

Purpose of the Invention The present invention has been made in view of the actual situation of conventional R4JL, and is capable of dealing with the desiliconization and dephosphorization of hot metal of large quantities. The purpose of this study is to propose a method for desiliconizing hot metal troughs that can achieve the following.

DISCLOSURE OF THE INVENTION The method for desiliconizing hot metal according to the present invention includes:
Adding a desiliconizing agent between the tap hole and the skin 7-
First desiliconization, then 1・-1−+− from Summer
It is characterized in that a desiliconizing agent is added during the process up to F (secondary desiliconization is performed).

In other words, the present invention provides a so-called two-stage desiliconization method in which a desiliconization agent is added to a cast-floor desiliconization process, which has not been conventionally carried out in the past, including a primary desiliconization process in which a C desiliconization agent is added to a casthouse desiliconization process, and a secondary desiliconization process in a Skimmer flow. By processing, after processing (,' Si
J < l), this method achieves 15%.

This invention method will be explained in detail below with reference to the drawings. In Figure 1, (1) is the blast furnace, (2) is the taphole, (3)
) is the tap runner, (4) is the skimmer, (5) is the hot metal runner, (
6) shows the slag outlet, and (7) shows the torpedo car. That is, the hot metal (8) discharged from the taphole (2) of the blast furnace (1) is transferred to the skinmer (4) installed in the taphole (3), where the hot metal (8) and slag (8-2) are discharged. is separated,
Slag (8-2) is discharged from the slag discharge port (6), and hot metal (8-2) is discharged from the slag discharge port (6).
) flows through the hot metal sluice (5) downstream of the skimmer (4) and reaches the torpedo car (7).

This invention is a primary desiliconization process in which a desiliconizing agent (9
-1) is added. The place where the desiliconizing agent is added in this primary desiliconization is not particularly limited, but usually up to the skimmer (4), the slag (8-2) covers the hot metal (8)-H and is mixed naturally. Since desiliconization efficiency may be low in this case, a location close to the taphole (2) is actually desirable.

In particular, it is more effective if a desiliconizing agent is added to the drop point of the hot metal flowing down from the taphole. Other methods to promote desiliconization include, for example, using a taphole cover to inject a solid desiliconizing agent together with N2 gas or air, or by adding a head to the tap sluice to reduce the carbon It is also possible to adopt a method in which a desiliconizing agent is stirred into the generated stirring flow. The addition rate of the desiliconizing agent in this primary desiliconization will be determined depending on the Si'J content, but at this stage, the molten pig iron will be covered with slag. Therefore, if a large amount of C is added, not all of it will react, so add it in an appropriate amount depending on the hot metal M and (Si) content.

The hot metal (8) that has undergone primary desiliconization in this way is separated into blast furnace slag and desiliconized slag by the skimmer (4) and flows to the hot metal sluice (5), where it falls into the torpedo car (7). Secondary desiliconization is performed by adding a desiliconizing agent (9-2) to the previous hot metal (8). Regarding the addition of the desiliconizing agent at this stage, after the first desiliconizing treatment (Si), depending on the amount, C/P: constant 1-1 can be added by injection method, etc. in which it is blown in together with N, gas, etc. can.

As described in L, this invention performs the de1 treatment using the H flow of the skimmer, so that the +ffl [5
It is fully possible to achieve (Si') in iJA hot metal to 0.15% or less, which is required for hot metal dephosphorization, in a blast furnace cast bed. Therefore, according to this invention, by solving the problems of increased process steps and increased processing time, it becomes possible to desiliconize a large amount of hot metal. These include iron oxide-based gases such as scale, fine ore, and sintered ore powder, and MnO-based or 02-containing gases.

Next, embodiments of the invention will be described.

Example A method in which a desiliconizing agent (sintered powder with an average particle size of 5 mm) is injected onto the tap sluice upstream of the skinmer into hot metal (temperature 1510"C) having the components shown in Table 1 that is tapped from a blast furnace. (air pressure 2 to da/c+l) for 20ks+/T to carry out primary desiliconization treatment, and then 15 kg of the same desiliconizing agent was applied to the hot metal after the primary desiliconization treatment on the hot metal trough downstream of the skinmer.
/T was charged for secondary desiliconization treatment.

Table 2 shows the hot metal components after the primary desiliconization treatment and the hot metal components after the secondary desiliconization treatment in this example.

As is clear from Table 2, the two-stage desiliconization treatment of the present invention was able to desiliconize Cs1) in the high (Si) content hot metal to -ro, 151 or less in the blast furnace cast bed.

Table 1: Composition of desiliconizing hot metal (%) Table 2 Composition of hot metal after desiliconization (%)

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the present invention. l...blast furnace, 2...tapping hole, 3...tapping sluice, 4...
... Cedar/Mar, 5...Hot metal gutter, 6...Slag discharge port, 7
...Torpedo car, 8...Hot metal, 9-1.9-2
...Desiliconizing agent. Figure 1

Claims (1)

[Claims] In a method for desiliconizing hot metal in a blast furnace tap culvert,
Hot metal characterized in that a desiliconizing agent is added between the taphole and the skinmer to perform primary desiliconization, and a desiliconizing agent is further added between the skinmer and the torpedo to perform secondary desiliconization. desiliconization method.