JPH0438807B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a hot metal pretreatment method in which a hot metal pretreatment agent is injected into hot metal flowing through a hot metal trough together with a carrier gas. <Prior art> As a method for pre-treatment of hot metal in a blast furnace casthouse, an injection lance is immersed in the hot metal flowing through a gutter.
Techniques have been developed to inject hot metal pretreatment agents along with carrier gas. JP-A No. 62-7809 discloses that by blowing a hot metal pretreatment agent sideways from the tip of a lance,
A technique for preventing wear and tear of refractories in the lower part of a hot metal gutter has been disclosed. Generally, when pre-treating hot metal using this method, increasing the amount of carrier gas will cause
Problems arise, such as intense and dangerous splashing and increased hot metal loss, heat taken away by the carrier gas which lowers the temperature of the hot metal, and increased load on the dust collector. There is a tendency to reduce it. If the amount of carrier gas decreases, the following problem will arise as a flip side to the above-mentioned problem. The hot metal flow is not sufficiently stirred in the width direction of the gutter, creating a so-called bypass flow in which the hot metal passes through with almost no reaction near the side walls of the gutter.The hot metal pre-treatment agent does not spread sufficiently in the width direction of the gutter.
Because the carrier gas rises along the side of the lance, the lance refractories are subject to severe wear and tear (when the amount of carrier gas is large, the stirring force is also strong, causing severe wear and tear on the lance). <Problems to be Solved by the Invention> The present invention has been made in order to solve the above-mentioned problems when the amount of carrier gas is small, and to provide a hot metal pretreatment method with good reaction efficiency and long lance life. It is. <Means for Solving the Problem> As a result of extensive research into hot metal pretreatment methods in hot metal runners, the present inventors found that the objective could be achieved by using a lance with a hot metal pretreatment agent injection nozzle that juts out laterally. We have found that this can be achieved, and based on this knowledge, we have completed the present invention. The present invention provides a hot metal pretreatment method in which a lance is immersed in hot metal flowing through a hot metal gutter, and a hot metal pretreatment agent is injected into the hot metal from the lance together with a carrier gas, in which a pretreatment agent injection nozzle protrudes laterally. This is a hot metal pretreatment method in which a lance with a protruding tip is immersed in hot metal, and a pretreatment agent and carrier gas are jetted away from the outer peripheral surface of the lance. <Function> In carrying out the present invention, a lance having a blowing nozzle with a flux and carrier gas ejection port extending laterally at the tip of the lance is immersed in a hot metal trough to pre-process the hot metal. It is good to do this. The effect will be explained below. FIG. 1 shows an example of the implementation of the present invention, and FIG. 4 shows an example of the conventional method. When the amount of carrier gas is reduced by the conventional method, the carrier gas bubbles float to the surface at a considerable distance from the side wall of the gutter, as shown in FIG. For this purpose, the bypass flow area 1 shown with diagonal lines in FIG.
0 is formed, and the hot metal flows downstream unreacted without contacting the hot metal pretreatment agent 8. On the other hand, the hot metal that has passed near the carrier gas floating area is stirred by bubbles and sufficiently reacts with the hot metal pretreatment agent, and the reaction progresses in some hot metal until it is almost saturated. However, since the reaction efficiency generally decreases near the point where the reaction is saturated, the total reaction efficiency of the unreacted hot metal that has passed through the bypass flow area and the hot metal that has passed through the bubble floating area and has undergone sufficient reaction is is lower than if the reaction occurred uniformly. Therefore, by using the protruding lance of the blow nozzle portion of the present invention shown in Fig. 1, the bias flow region is reduced or eliminated, and the hot metal pretreatment agent is uniformly stirred in the width direction of the gutter. Due to the uniform distribution in the direction, the reaction efficiency is improved. In addition, in the conventional method, as shown in Fig. 4, the floating region of air bubbles is formed near the outer periphery of the lance along the lance, so the side surfaces of the lance are severely worn out due to the agitation force of the air bubbles. By using the method of the present invention as shown, the floating region of air bubbles is separated from the side surface of the lance and mixed together, so that wear and tear on the lance is reduced and the life of the lance is extended. <Example> An example of the present invention will be described using a desilicon treatment in a hot metal trough as an example. However, the present invention is not limited to desiliconization treatment, but can be widely applied to hot metal pretreatment such as dephosphorization and desulfurization treatment. Table 1 shows the specifications of the hot metal sluice and lance used in the experiment, as well as the experimental conditions. A four-hole lance shown in FIGS. 1 and 4 was used as the lance. Realization is the gutter width,
I tried changing the dimensions of the lance overhang, but the gutter width
The case of 1000mm is shown as an example. Si before treatment = 0.4%
Figure 3 shows the diameter of the lance overhanging portion and the Si (%) after treatment when it is constant at ±0.01%. The same figure also shows the results of the conventional method using a lance without an overhanging part. As is clear from FIG. 3, if the method of the present invention is used, the desiliconization efficiency is significantly improved. This effect is particularly significant when the diameter of the lance projecting portion is 200 mm or more, that is, 20% or more of the gutter width. Regarding lance life, with conventional lances without overhangs, the throughput per lance is
The lance was 1500t/piece, but in the case of the lance with an overhanging nozzle part of the present invention, it was 1800 to 2400t/piece, and by having the overhanging part, air bubbles do not come into direct contact with the lance, so the life of the lance is significantly extended. FIG. 5 shows the relationship between the lance refractory wear index and (overhang diameter - lance diameter)/lance diameter.
The lance refractory wear index is the amount of refractory wear of an overhanging lance when the amount of refractory wear when using a lance with a lance diameter of 150 mmφ without an overhang portion is set as 1. As is clear from FIG. 5, when (overhanging diameter - lance diameter)/lance diameter is 0.5 or more, the lance wear prevention effect is significant.

【table】

[Table] From the above results, it is clear that if the hot metal pretreatment method in which the hot metal pretreatment agent is immersed in a lance with a laterally protruding hot metal pretreatment agent injection nozzle is used, it will be possible to bypass the unreacted metal. The flow decreases or disappears, the reaction efficiency increases because the hot metal pretreatment agent is evenly distributed in the width direction of the gutter, and the floating area of the bubbles coming out of the nozzle moves away from the lance, reducing wear on the lance refractory. It has become clear that the effect of greatly extending the life of the lance can be obtained even with a small amount. In addition, if the shape of the lance has a protruding blow nozzle part, the diameter and shape of the protruding part,
There are no restrictions on the direction or number of nozzles. For example, in the diagonal nozzle projecting lance shown in Figure 2, the hot metal pretreatment agent conveyed together with the carrier gas does not bend at right angles in front of the nozzle, so when it is ejected into the hot metal, it maintains the velocity of the hot metal. The pretreatment agent penetrates deeply into the hot metal and is well dispersed, which is effective in improving reaction efficiency. Note that the structure of the lance used in the present invention is not limited to use only for preliminary treatment of hot metal passing through a hot metal gutter, but also for refining hot metal in a torpedo car or hot metal ladle, and for molten metal in a ladle. It can be used for the purpose of preventing erosion of the lance, increasing the stirring effect, or improving the dispersion of the blown gas or flux when blowing carrier gas and powder or only gas into molten metal, such as refining. <Effects of the Invention> Using the present invention, it is possible to increase the reaction efficiency in hot metal pretreatment in the hot metal trough and further extend the life of the lance.

[Brief explanation of drawings]

FIG. 1 is a front sectional view explaining the present invention, and FIG.
The figure is an explanatory diagram showing a modified example of the lance used in the present invention, Figure 3 is a graph showing the experimental results using the present invention, Figure 4 is a front cross-sectional view explaining the conventional method, and Figure 5 is a diagram showing a modified example of the lance used in the present invention.
The figure is a graph showing the relationship between the lance refractory wear index and (overhang diameter - lance diameter)/lance diameter. 1...Lance, 2...Lance overhang, 3...
...Hot metal pretreatment agent injection nozzle, 4...Hot metal gutter,
5... Hot metal, 6... Slag, 7... Carrier gas bubbles, 8... Hot metal pre-treatment agent, 9... Splash, 10... Bypass flow region, 11... Lance consumption region.

Claims (1)

[Claims] 1. In a hot metal pretreatment method in which a lance is immersed in hot metal flowing through a hot metal gutter and a hot metal pretreatment agent is injected from the lance into the hot metal together with a carrier gas, the tip of the pretreatment agent injection nozzle is set so that it projects laterally. A hot metal pretreatment method characterized in that a lance protruding from the lance is immersed in the hot metal, and a pretreatment agent and carrier gas are jetted out to a position away from the outer peripheral surface of the lance.