JPH02104606A - Method for desiliconizing molten iron on casting floor - Google Patents

Abstract

PURPOSE:To improve desiliconizing ratio and to increase molten iron receiving quantity in a molten iron ladle by specifying grain aize of desiliconizing agent in top charging method which uses returned ore of mill scale or sintered ore as the desiliconizing agent. CONSTITUTION:At the time of executing the desiliconization on a casting floor in the top charging method which uses the returned ore of mill scale or sintered ore as the desiliconizing agent, the grain diameter of the above desiliconizing agent is regulated to 1-3mm. This desiliconizing agent 2 is discharged from a hopper 1 with an electromagnetic vibrating feeder 3, and at this time, the discharged quantity is detected with a load cell 8 to execute the prescribed discharged quantity. The desiliconizing agent supplied on the surface of the molten iron 5 flowing a molten iron trough is mixed with the molten iron at the time of charging the molten iron from a tilting ladle 6 into the molten iron ladle 7 to execute the desiliconization of the molten iron. At the time of making the grain size largely, the desiliconizing ratio is lowered and at the time of coming the desiliconizing ratio to <70%, as desulfurizing ratio at the following process is not executed at good efficiency, the grain size of the desiliconizing agent is regulated to <=3mm, and on the other hand, at the time of making the grain size finely, aa the molten iron quantity charged into the molten iron ladle 7 is reduced by increasing bulging of the molten iron, this is regulated to >=1mm.

Description

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

[Prior Art] In recent years, there has been a strong demand for improving the quality of hot metal due to the demand for producing high-grade steel in the steel manufacturing process and reducing smelting costs.

For this reason, a desiliconization agent is added to the hot metal to perform desiliconization treatment. Methods for performing the desiliconization treatment include an overlay method in which a desiliconizing agent is charged onto the surface of hot metal, and an injection method in which a desiliconizing agent is injected into the hot metal together with a carrier gas. Among these methods, the injection method requires carrier gas supply equipment, and the overlay method is used as a simple method.

[Problems to be Solved by the Invention] However, when using mill scale or sintered ore return ore as a desiliconizing agent, the desiliconizing rate may be reduced depending on the particle size of the desiliconizing agent, or the desiliconizing rate may be reduced due to forming, which may cause the hot metal ladle to The amount of hot metal charged is small.

There is a possibility that this may happen.

The present invention aims to provide a method for desiliconizing a hot metal casting bed that can improve the desiliconization rate and increase the amount of pig iron received in the hot metal ladle by adjusting the particle size of the desiliconizing agent.

[Means and effects for solving the problem] The method for desiliconizing a cast bed of hot metal according to the present invention is a method for desiliconizing a cast bed by an overlay method using mill scale or return ore of sintered ore as a desiliconizing agent. The method is characterized in that the particle size of the desiliconizing agent is 1 to 3 mm.Since the particle size of the special desiliconizing agent is 311Ii or less, the desiliconizing efficiency is high, and the particle size is lll11. Because of the above, forming is reduced and the amount of pig iron received into the hot metal ladle is increased.

[Examples] Examples of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows a desiliconization treatment apparatus for carrying out the method of the present invention. 1 is a desiliconizing agent hopper that accommodates the desiliconizing agent 2; 3 is an electromagnetic vibration feeder that supplies the desiliconizing agent to the surface of the hot metal 5 flowing through the hot metal trough; and 8 is a load cell that detects the amount of the desiliconizing agent in the hopper 1. be.

Further, 6 is a tilting ladle that receives hot metal from hot metal N4 and charges the hot metal into hot metal ladle 7.

The operation of the desiliconization treatment apparatus configured as above will be explained. The desiliconizing agent in the hopper 1 is cut out by an electromagnetic vibration feeder 3, the amount of cut-out at this time is detected by a load cell 8 provided in the hopper 1, and a predetermined amount of cut-out is performed. The desiliconizing agent supplied to the surface of the hot metal is poured into the pouring pot 6.
When the hot metal is charged into the ladle 7, it is mixed with molten iron, and the hot metal is desiliconized.

FIG. 2 is a graph showing the relationship between the particle size of the desiliconizing agent and the desiliconizing efficiency. As can be understood from this figure, as the particle size increases, the desiliconization efficiency decreases, but when this becomes less than 70%, the desulfurization carried out in the subsequent process becomes less efficient.
Therefore, desulfurization is performed in the process of converter smelting, and the purpose of desiliconization treatment cannot be achieved. Silica removal efficiency 70
The upper limit of the particle size corresponding to % is 3■.

Furthermore, although the smaller the particle size, the better the desiliconization efficiency becomes, this also causes so-called forming, in which the hot metal swells due to the gas generated by the desiliconization reaction. When this forming occurs, the amount of hot metal charged into the hot metal ladle decreases.

Figure 3 shows the particle size of the desiliconizing agent and the relative acceptance rate of the hot metal ladle (a full ladle is 1
00%). According to this, when the grain size is less than 1 mm, the relative acceptance rate does not reach 75%. If the relative acceptance rate is low, it will be difficult to operate the limited number of hot metal pots. In other words, the number of hot metal pots is determined based on the assumption that they receive a predetermined amount of hot metal, and as the amount of hot metal to be received decreases, it becomes necessary to increase the number of hot metal pots accordingly. This will not only mean an increase in the number of hotpots, but will also have an impact on the layout of the factory, including an increase in the number of times the iron can be received, repairs, and a hotpot storage area. The above-mentioned relative pig iron receiving rate of 75% is the lower limit of the range that does not hinder the operation of the hot metal ladle.

Thus, the preferred particle size range of the desiliconizing agent used in the desiliconization treatment of hot metal by the overburden method is said to be 11 to 3 mm.

[Effects of the Invention] Since the particle size range of the desiliconizing agent is set to 1 am to 3 mm, it is possible to improve the desiliconization rate and increase the relative amount of pig iron received in the desiliconization treatment of hot metal by the overlay method.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view of a desiliconization treatment apparatus used in the method of the present invention, Fig. 2 is a graph showing the relationship between the particle size of the desiliconizing agent and desiliconizing efficiency, and Fig. 3 is a graph showing the relationship between the desiliconizing agent particle size and desiliconizing efficiency. FIG. 2 is a graph diagram showing the relationship between grain size and relative pig iron acceptance rate. 1... Desiliconizing agent hopper, 2... Desiliconizing agent, 3... Electromagnetic vibration feeder, 4... Hot metal trough, 5... Hot metal, 6...
・Pouring pot, 7...Hot metal pot, 8...Load cell.

Claims (1)

[Claims] A cast bed desiliconization method using mill scale or sintered ore return ore as a desiliconization agent, the method comprising: casting bed desiliconization using the overlay method, characterized in that the particle size of the desiliconization agent is 1 mm to 3 mm. Castbed desiliconization method.