JPS61149417A - Method for subduing slag foaming - Google Patents

Abstract

PURPOSE:To inhibit the overflow of foaming slag formed by adding dephosphorizing and desiliconizing agents to molten pig iron in a torpedo car by blowing an inert gas into the space between the surface of the molten pig iron and the pig iron receiving hole of the torpedo car. CONSTITUTION:Molten pig iron 2 in a torpedo car 1 is pretreated by adding dephosphorizing and desiliconizing agents 12 from a lance 10. At this time, an inert gas is blown into the space between the surface 8 of the molten pig iron 2 and the pig iron receiving hole of the car 1 from blowing pipes 5A, 5B fixed at positions about 500mm below the pig iron receiving hole. The amount of the inert gas blown is about 1/3-1/4 of the amount of gaseous CO2 generated. Thus, the overflow of foaming slag from the pig iron receiving hole due to CO2 generated by adding the agents 12 is inhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for settling slag and 7-ohming, and more specifically, to a method for settling slag and slag generated when pretreatment such as dephosphorization and desiliconization is applied to hot metal in a pig iron mixing car. Concerning how to calm wet fields.

Prior art and its problems As a conventional method for suppressing slag forming during hot metal pretreatment, it has been considered to attach a lid to the pig iron receiving port of the pig iron mixing car. However, since the lid, which is constantly exposed to high temperatures, uses expensive materials such as heat-resistant materials, equipment costs are high and maintenance costs are considerable, making it impractical. Under these circumstances, as a means of suppressing the slag forcing phenomenon, it is recommended to reduce the blowing speed of dephosphorizing and desiliconizing agents to reduce the amount of carbon monoxide generated, or to reduce the amount of hot metal loaded into pig iron mixing cars. Currently, they are forced to operate to secure free board. Such operations reduce the temperature of the hot metal by extending the treatment time and increasing the cost of refractories in the mixed pig iron car.

OBJECTS OF THE INVENTION An object of the present invention is to provide a method that can reliably calm down slag foam without affecting preliminary treatments such as dephosphorization and desiliconization applied to hot metal in a pig iron mixing car. .

The above object of the present invention is to provide a hot metal pretreatment process characterized by blowing an inert gas such as nitrogen into the internal space defined by the molten metal surface and the pigtail receiving port loaded on the hot metal mixing car. This is achieved by the slag forming method of settling.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Now, embodiments of the method of the present invention will be described as follows with reference to embodiments shown in the accompanying drawings.

FIG. 1 shows preliminary treatments such as dephosphorization and desiliconization applied to hot metal 2 loaded on a pig iron mixing car 1.

A lance lO is inserted from the pig iron receiving port 11 of the pig iron mixing car 1, and its tip is inserted deeply into the layer of hot metal 2 through the slag layer 3. The upper end of the lance 10 is connected to a tank 13 through a flexible tube 14.
It is connected to a supply source of a dephosphorizing agent/desorbing agent 12 such as the like, and these processing agents are discharged from the lower end. Reference numeral 4 indicates a space between the lower surface of the upper end of the pig iron mixer car 1 and the upper surface of the slag 3, that is, a freeboard.

During hot metal pretreatment, the solid oxygen source of the dephosphorization agent and desorption agent added to the hot metal reacts with carbon in the hot metal to produce carbon monoxide (Co).
occurs. This carbon oxide causes the slag generated during the process to form and overflow from the receiving port of the pig iron mixer car.

Fig. 2 shows an embodiment of the method of the present invention.
Injection pipes 5A and 5B for injecting an inert gas such as nitrogen in the direction of the lance 10 are provided on the wall of the pig iron mixing car above the hot metal level 8 of the hot metal 2 loaded on the tank. The injection pipes 5A and 5B can be installed anywhere as long as they are below the receiving port.
It is considered that the lower side of my level is preferable. The amount of inert gas blown in is preferably about % to % of the amount of CO gas generated. The reasons for using an inert gas such as nitrogen as the injected gas are to prevent CO gas from burning, extend the life of the lance, and protect the refractory. Figure 3 shows the method shown in Figure 2. This shows a modified embodiment of the invention, in which a lance 7A for blowing out nitrogen gas is provided separately.

7B is inserted into the freeboard portion 4 from the pig iron receiving port 11 and an inert gas such as nitrogen gas is blown into it to agitate the slag on the surface of the hot metal and prevent slag forming.

The invention will now be explained by way of example.

EXAMPLE 3 In a 50T pig iron mixer car, inert gas was blown into the freeboard portion during hot metal pretreatment using the method shown in FIG. 3 as follows.

(1) Two inert gas injection lances were charged from the pigtail receiving port.

(2) The tip of the inert gas injection balance was fixed at a position 50 (1+m) below the pigtail receiving port of the pig iron mixer.

(3) Nitrogen was used as an inert gas.

(4) Flow rate of inert gas is 4 to 6 Nm3/min
And so.

(5) Inert gas was continuously blown from the start to the end of the pretreatment.

By continuously blowing inert gas into the freeboard during hot metal pretreatment, the following effects were obtained (+) Slag foaming overflowing from the pig iron receiving port of the pig iron mixing car could be suppressed. .

(b) Hot metal treatment time was reduced by 5 minutes.

(c) It was possible to increase the amount of pig iron received by the pig iron mixing car by 10'l'.

Effects of the invention As shown above, the effect obtained by blowing an inert gas such as nitrogen into the freeboard of a pig iron mixer car is that it can suppress slag forming that overflows from the pig iron receiving port of the pig iron mixer car, and therefore, it can suppress the slag forming that overflows from the pig iron receiving port of the pig iron mixer car. These include shortening the processing time and increasing the amount of pig iron that can be received by the pig iron mixing car.

In addition, the effects of the inert gas blown into the freeboard include preventing the combustion of CO gas, extending the life of the lance, and protecting the refractory.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing hot metal pretreatment carried out in a pig iron mixing car; Fig. 2 is a sectional view showing an embodiment of the method of the present invention; Fig. 3 is a sectional view showing a modified embodiment of the embodiment shown in Fig. 1. It is a diagram. 14 Flexible tube

Claims (1)

[Claims] A method for calming slag forming during pretreatment of hot metal, which is characterized by blowing an inert gas such as nitrogen into the internal space defined by the hot metal surface of hot metal loaded in a pig iron mixing car and the pigtail receiving port.