JPH03281714A - Method for desiliconizing molten iron - Google Patents

Abstract

PURPOSE:To simply and continuously desiliconize molten iron with high reaction efficiency and to reduce unit consumption of desiliconizing agent by charging granular oxygen source into the molten iron shifted from a molten iron conveying vessel to a charging ladle and stirring the molten iron with the shifting. CONSTITUTION:At the time of shifting the molten iron 4 from the molten iron conveying vessel 2 to the charging ladle 3, the granular oxygen source 5 is charged to the above molten iron 4 through an oxygen source charging chute 1. As the above oxygen source 5, either one of iron oxide, sintered ore, manganese ore, etc., is used. By making about 50-100ton/min of flowing-out velocity of the above molten iron 4, the stirring energy in the charging ladle 3 is obtd. according to this flowing velocity. The above charged oxygen source 5 is sufficiently stirred with this stirring energy at the time of shifting and [Si] in the molten iron 4 is oxidized and removed with high reacting efficiency.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for desiliconizing hot metal.

[Prior Art] Hot metal tapped from a blast furnace is subjected to preliminary desiliconization treatment to make the hot metal [Si] concentration suitable for the amount of slag and slag basicity required for desorption in converter refining. There is.

Various methods have been proposed for preliminary treatment for desiliconization, depending on the combination of treatment location, type of desiliconization agent, and bath stirring method.
Among these methods, the so-called cast bed desiliconization method, in which desiliconization is carried out continuously while passing through the blast furnace tap trough, and the method in which the desiliconization is carried out by hatching in a transport container are often adopted.

It is known that in these desiliconization methods, stirring energy is effective for the desiliconization reaction. Figure 2 shows that in the casthouse desiliconization method, the higher the tapping speed, which affects the stirring energy, the higher the desiliconization rate in the tilting runner (100°101st Nishiyama Memorial Technical lecture [Recent trends in steelmaking technology using stirring J, ■Iron and Steel Association, p104
~114, 1982).

Therefore, when desiliconizing the molten metal by installing a 1Mn cylindrical molten metal body between the blast furnace cast bed trough and the tilting trough, the outflow velocity of the hot metal falling from the stock trough to the tilting trough and the flow rate of the cylindrical molten metal channel body are determined. Desiliconization method in which the ratio to the road cross-sectional area is set in a specific range
104414), or when pre-refining agent is injected into the hot metal flowing in the blast furnace gutter to perform out-of-furnace refining such as desiliconization, a hot metal stirrer is installed on the F flow side of the refining agent injection nozzle to stir the hot metal. Meanwhile, an apparatus for preliminary refining has been proposed (Japanese Unexamined Patent Publication Nos. 1983-202011).

[Problems to be solved by the invention] Although the gunstock desiliconization method described above can easily perform large-scale processing without increasing process time, the stirring power is low and the desiliconization rate is low. This is thought to be due to the fact that the outflow rate is actually about 10 tons/min, which limits the stirring energy. Even in the case of equipment equipped with a cylindrical molten metal channel body, it is not expected to obtain a sufficient desiliconization rate because the flow rate of the iron extracted from the blast furnace is limited to about 10 mm/min. Since the cylindrical molten metal channel body is provided, there is a problem in that the space between the gutter becomes complicated.

The method of providing an agitator to agitate the molten metal in the blast furnace gutter requires equipment such as an agitator, and is expensive and complicated.

On the other hand, the method of batch processing in a transport container requires equipment such as a 191 stirrer, and is similarly expensive and complicated.

The present invention aims to solve the above problems (f), and aims to provide a continuous desiliconization method with a high desiliconization rate without using equipment such as a stirrer.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method for transferring hot metal by adding a granular oxygen source to the hot metal when transferring the hot metal from the hot metal transport container to the charging ladle. [Sil
This is a method for desiliconizing hot metal, which is characterized by oxidizing and removing.

[Function] In the present invention, is the molten pig iron transferred from the container to the charging pot? 8
Since the amount of hot metal required for one charge of the converter is processed, a flow rate of about 50 to 100 tons/min can be expected.
The corresponding stirring energy can be increased, and if a granular oxygen source is added to the hot metal when transferring it, it will be stirred by the stirring energy and a sufficient desiliconization reaction can be carried out. Yes, it is possible to increase the reaction efficiency.

The oxygen source used in the present invention is iron oxide, sintered ore, manganese ore, etc. In this case, the iron oxide etc. needs to be in the form of powder. The reason why the powder is made into granules is that when it is added to hot metal, it dissolves sufficiently and can contribute to the reaction.

[Example] The present invention will be explained below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of the present invention. In FIG. 0, 1 indicates an oxygen source charging chute. 1 The method of the present invention is used to transfer hot metal 4 from a hot metal transport container 2 to a charging ladle 3. First, an oxygen source 5 is charged into the hot metal 4 through the oxygen source input chute 1, and [S1] is oxidized and removed by stirring the hot metal 4 generated by the transfer. In this case, as the oxygen source 5, granular iron oxide or the like can be used.The size of the granules is not particularly limited, but it may be of a granular size that can be dissolved during stirring during transfer of hot metal. In this case, iron oxide is heavy with a specific gravity of around 5, so
Even in powder form, it can be mixed into hot metal, resulting in less scattering loss.

Next, an experimental example using the method of the present invention will be explained. By the method shown in FIG. 1 above, iron oxide mainly composed of am predetermined iron oxide was continuously charged into the hot metal flow from the charging chute.

The actual conditions and results are shown below.

Head difference between hot metal transport container 22 and charging pot 23: 2 to 6 m (average 35 m) Flow rate near 5 Lon/min Stirring nitrogen: 178 w/lon Silica removal rate, 80%
(Initial [Si] = 0.5%, oxygen supply 5.ONg'
/lon) When a blast furnace gun stock is used as a comparative example, the head is 2 to 5 m (35 m on average). oxygen supply 5
, ONm'/ton) According to the present invention, the desiliconization rate is clearly increased by my
It can be seen that there is an improvement in In addition to improving the reaction efficiency in the above steps, sudden abnormal reactions of unreacted iron oxide and heat loss due to oxidative decarburization are eliminated, and the unit consumption of the desiliconizing agent can be reduced.

[Effects of the Invention] According to the present invention, the reaction efficiency can be improved and the unit consumption of desiliconization agent can be reduced by the simple method of adding an oxygen source to the hot metal when transferring the hot metal to the charging ladle. This is an invention with great effects.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing the relationship between the tapping speed and the desiliconization rate in a tilting runner according to a conventional desiliconization method. 21-...Oxygen source input chute.

Claims (1)

[Claims] When transferring the hot metal from the hot metal transport container to the charging ladle, a granular oxygen source is introduced into the hot metal, and [Si] is oxidized and removed by stirring the hot metal generated by the transfer. Desiliconization method.