JPH0421816Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a continuous molten iron refining device, and in particular, it applies a refining agent (desiliconizing agent, dephosphorizing agent, desulfurizing agent, etc.) to the molten iron passing through a molten iron gutter. When continuously refining by injection, it not only reduces the scattering loss of molten iron, but also makes effective use of the refining agent and improves refining efficiency, and also suppresses erosion of the refining agent injection lance and molten iron gutter. This invention relates to a continuous refining device that can extend its life. In this specification, the description will mainly be given to an apparatus applied when hot metal tapped from a blast furnace is subjected to continuous desiliconization treatment on a cast bed, but the present invention is of course not limited to this. The present invention can be similarly applied to various treatments such as continuous dephosphorization or desulfurization of hot metal or molten steel as it passes through the gutter.

[Conventional technology] As a relatively new outside-furnace desiliconization method that replaces the ladle desiliconization method, a desiliconization agent is introduced into the hot metal flowing through the tap pipe of a blast furnace casthouse, and the desiliconization treatment is performed before it is received in the ladle. The hot metal sluice desiliconization method that can be completed is becoming popular. That is, this method includes a method in which a desiliconizing agent is introduced into hot metal flowing through a hot metal trough, and the desiliconizing agent is drawn into the hot metal using the stirring effect produced by the flow of hot metal to perform desiliconization, and the above-mentioned method. Considering that the stirring and entrainment effects are weak in the method described above, an injection lance is inserted into the hot metal flowing through the hot metal trough, and a granular desiliconizing agent is injected from the lance together with a carrier gas to induce a reaction between the hot metal and the desiliconizing agent. In addition, since the above method has the problems described below, in order to prevent lance erosion, a granular desiliconizing agent is sprayed together with a carrier gas from above the hot metal flowing in the hot metal gutter, and the hot metal flow is A method of increasing the contact efficiency between the desiliconizing agent and the hot metal by using the stirring force generated by the spraying and improving the desiliconization efficiency is known. This method has been praised as an extremely efficient method. In particular, in the above method, it is thought that a high level of desiliconization efficiency is achieved because the bubbling caused by gas injection from the lance and the stirring caused by the turbulent flow of the hot metal combine to increase the stirring efficiency. There is.

The equipment used to carry out the method shown above is as shown in Figure 3 (schematic longitudinal cross-sectional view) and Figure 4 (schematic cross-sectional view), and the equipment to be newly prepared is omitted. Desiliconization treatment is carried out using only the silica injection lance 2, by immersing the lance 2 in a suitable position in a normal hot metal trough 1 and injecting the desiliconizing agent F into the hot metal M together with the carrier gas G from the lance 2. will be carried out.

[Problems to be solved by the invention] However, the above method is not completely free of problems, and there are still various problems that need to be improved, such as those listed below. This can be said to be a common drawback when performing various refining treatments.

(a) Bubbling of the blown gas causes hot metal to scatter outside the gutter, which is extremely dangerous and also leads to loss of hot metal.

(b) The refractories that make up the hot metal trough and injection lance are severely eroded near the slag line.

(c) The desiliconizing agent has a lower specific gravity than the hot metal and quickly floats to the surface of the hot metal after being blown, so a considerable amount of the desiliconizing agent is discharged unreacted.

(d) The desiliconizing agent is blown downward along with the carrier nozzle from the nozzle opened at the leading edge of the lance, but this blowing flow locally erodes the lower surface of the hot metal gutter, which reduces the lifespan of the hot metal gutter. is further shortened.

Moreover, the lance is usually suspended in a cantilevered manner from above the hot metal surface, with the tip immersed into the hot metal, and the rapid flow of high-mass hot metal (specific gravity: approx.
6.7, flow velocity: approximately 80 cm/sec), causing significant vibration, and the lance itself is susceptible to minute cracks due to the impact reaction that occurs when the desiliconizing agent is blown into the lance. When such cracks occur, hot metal or slag infiltrates into the cracks, significantly accelerating erosion, and causing the lance tip to break within a short period of time.

The above-mentioned method has been developed against this background, but in the method described above, hot metal and desiliconizing agent scatter violently, and countermeasures such as reducing the spraying speed are required to prevent scattering, making it impractical. Less sexual. Therefore, we are forced to return to the above method again, and when implementing the method, it is important to eliminate or alleviate the problems shown in (a) to (d) above. This can be said to be a common problem in cases where various refining processes such as dephosphorization and desulfurization are performed on the gutter. Under these circumstances, the present invention aims to provide a continuous refining device that can solve the above-mentioned problems all at once.

[Means for Solving the Problems] The continuous refining device of the present invention that has achieved the above objectives is a continuous refining device of the present invention in which a lance whose tip is immersed with a refining agent injected into the hot metal flowing in the hot metal gutter is disposed. In the refining equipment, the hot metal gutter reaches the lance immersion position and has its upper part wider than the bottom side of the gutter to form a slag retention area, and the refining agent injection lance has a sideways jetting nozzle from near its tip. The gist is that the lance is open and the tip of the lance is brought into contact with the lower surface of the hot metal trough.

[Function] In order to eliminate or suppress the above-mentioned problems, the present invention devises the configuration of the hot metal trough while taking into consideration the relationship with the immersion position of the blowing lance, and also devises the structure and arrangement method of the lance. Adding. That is, as will be made clear in the examples below, in the present invention, the hot metal gutter is formed near the immersion position of the refining agent injection lance and the upper part thereof is wider than the bottom of the gutter to form a slag retention section. With this configuration, the following effects are achieved.

(b) The area around the upper part of the lance immersion position (gas injection position, i.e., gas bubbling position) in the hot metal gutter is made wide, which prevents hot metal from scattering outside the gutter and improves safety. Problems of loss and environmental pollution will also be suppressed.

(b) Erosion that occurs near the slag lines of hot metal sluices and lances is thought to occur because the refractory components in these react with iron oxide (FeO), etc., which are by-products of the smelting process, and are leached out. Particularly in areas where the slag flow rate is high and is vigorously agitated by bubbling, erosion progresses rapidly as frictional force increases. However, in the present invention, as described above, the area above the lance immersion position of the hot metal trough is widened to form a slag retention area, and the flow velocity of the slag produced by the refining process becomes very slow in this area. As a result, the frictional force caused by the flow of slag is reduced, and erosion of the hot metal sluices and lances is significantly suppressed. Moreover, the contact time between the hot metal and the refining agent is extended by the amount that the flow rate of the slag is reduced in the slag retention section, so that the refining efficiency can be improved and the loss of the refining agent can be reduced.

Furthermore, in the present invention, the jet nozzle provided on the refining agent injection lance is opened sideways from near the tip of the lance, and the tip of the lance is configured to abut against the lower surface of the hot metal gutter, thereby achieving the following effects. Make it work.

(c) Since the refining agent is injected from the horizontally formed injection nozzle, the refractory material on the lower surface of the lance installation position in the hot metal trough is not locally eroded, and the life of the hot metal trough is extended.

(d) In addition, the tip of the lance is in contact with the lower surface of the hot metal trough and is stably supported from above and below, so that vibrations caused by the collision of the hot metal flow and impact reactions caused by the injection of refining agents are prevented. There is less vibration, and the occurrence of cracks due to the vibration is suppressed, resulting in an extension of the life of the lance itself.

The continuous smelting device of the present invention includes a gutter having a wide slag retention section formed in the upper part of an arbitrary position as described above;
The essential component is a blowing lance whose tip is immersed in contact with the hot metal flow path at the relevant location, and by selecting a refining agent, it is possible to perform desiliconization, dephosphorization, or desulfurization. can. Further, these refining agents may be blown into the hot metal from a blowing lance along with a gas flow such as argon or nitrogen.

[Examples] The configuration and effects of the present invention will be further clarified with reference to the drawings showing examples below.

Figures 1 and 2 show an embodiment of the present invention, where Figure 1 is a schematic plan view and Figure 2 is a -
A diagram corresponding to a line cross section is shown, in which 1 is a hot metal trough, 2 is a lance, 2a is a jet nozzle, 3 and 4 are skimmers, and 5
indicates the slag outlet, M indicates the hot metal, S indicates the smelting slag, F indicates the refining agent, and G indicates the gas, and the arrows indicate the flow of the hot metal. The hot metal M sent from the left side of Fig. 1 flows to the right after the hot metal slag etc. are removed at the skimmer 3, and after being subjected to the refining process at the lance placement position, the generated refining slag S is While being discharged from the slag discharge port 5 at the right end, the refined hot metal M passes under the skimmer 4 and flows downstream.

As is clear from these figures, in the present invention, a slag retention section 1b with a wide upper part is formed at an arbitrary location in the hot metal gutter 1, and a hot metal flow located approximately in the center of the slag retention section 1b is formed. A lance 2 is immersed in the channel 1a with the tip of the lance 2 in contact with the lower surface of the channel, and refining is performed by blowing a refining agent together with gas such as argon from an injection nozzle 2a that opens horizontally near the tip of the lance 2. It can be done. In this case, if a normal hot metal sluice is used, the hot metal will flow through bubbling as described above or as shown schematically in Figure 3 (schematic vertical cross-sectional view) and Figure 4 (corresponding to the cross-sectional view taken along the line - in Figure 3). The hot metal dust (including hot metal and refining agent) generated on the surface may scatter to both sides of the hot metal sluice 1, which not only poses a risk of harm to workers, but also significantly pollutes the environment, and furthermore causes loss of hot metal and refining agent. invite. However, with the present invention, as shown in Figures 1 and 2, a wide slag retention area 1b is formed around the upper part of the lance immersion position, that is, the bubbling position, so most of the scattered molten metal is There is no fear that the slag will fall into the slag retention section 1b and be collected, causing harm to workers or causing hot metal loss. Incidentally, if a cover 6 is attached to cover the bubbling portion of the hot metal trough 1 as shown by the chain line in FIG. 2, problems caused by scattering can be more reliably prevented.

Furthermore, by using the device of the present invention, in addition to the above-mentioned effects, it is possible to suppress the corrosion of refractories progressing near the slag line of the hot metal trough 1 and lance 2, and to
It also has the effect of increasing refining efficiency. That is, as explained earlier, it has been confirmed that in hot metal sluice refining using the gas injection refining method, the refractories near the slag lines of the hot metal sluice 1 and lance 2 are severely eroded. [For example, the areas indicated by diagonal lines A and B in Fig. 4] The main causes of this corrosion are (a) iron oxide generated near the slag line due to intense stirring during smelting, which causes refractory damage to hot metal gutters and lances; (b) Slag S has a relatively high melting point and high viscosity, and as it flows at high speed while undergoing strong bubbling, the refractory is worn out by the frictional force. It is thought that these factors act additively or synergistically and the refractories near the slag line are rapidly eroded. However, in the present invention, the structure of the hot metal trough 1 as shown in the figure is By doing so, erosion of gutters and lances can be significantly suppressed. To explain this point in more detail, in the present invention, a wide slag retention part 1b is formed in the upper part near the refining agent injection position, and the generated slag S after contributing to refining while floating in the hot metal M. Slag rises to the surface of the hot metal due to the difference in specific gravity, but since the flow path is formed as a wide slag retention area as shown in the figure, the flow of slag S in this area is slower than that of the hot metal flowing through the hot metal flow path 1a. It becomes very slow. Therefore, the frictional force generated by the slag flow as described above is drastically reduced, and the physical erosion seen near the slag line is greatly suppressed. Regarding the reaction with iron oxide, which is another main cause of refractory corrosion, since the slag retention area 1b formed at the bubbling position is expanded as described above, the generated iron oxide, etc. The concentration per unit area of iron oxide, etc., which is dispersed throughout the refractory and eventually advances the erosion of the refractory, becomes extremely low, and chemical erosion is also significantly suppressed. As a result of these physical and chemical corrosion suppressing effects being exerted synergistically, corrosion of the refractory near the slag line can be minimized. The slag S slowly flowed down the wide slag retention part 1b.
After moving to the right side of Fig. 1, the slag S flows down at high speed along the hot metal sluice 1 of normal width, but at this point, the iron oxide concentration in the slag S decreases due to the progress of the desiliconization reaction. Therefore, corrosion of refractories does not progress much. However, as shown in Figure 5 (plan view),
If the wide slag retention part 1b is formed to be long in the downstream direction, the effect of retarding the slag flow velocity will be more effectively exerted, and as a result, erosion on the downstream side of the bubbling position can be effectively suppressed. I can do it.

Incidentally, the hot metal M scattered by bubbling once falls onto the slag retention section 1b, undergoes a refining treatment through the slag S layer containing a valuable refining agent, and then merges with the hot metal M in the hot metal flow path 1a below. The structure is such that the flow velocity of the slag S is slowed down at the part where the most powerful refining is carried out, and the valuable refining agent components in the slag S come into contact with the hot metal M efficiently in that part, so that the refining efficiency itself is improved. This also reduces waste loss of valuable refining agents, making it possible to reduce the unit consumption of refining agents to ensure the same refining efficiency.

By the way, it is possible to widen the entire hot metal channel including the hot metal channel at the lance immersion position (below the slag line) in the hot metal channel, but in a hot metal channel with such a configuration, it is difficult to prevent slag and hot metal from scattering. However, it is not possible to obtain the effect of improving refining efficiency as obtained by the present invention. In other words, when the entire lance immersion position is widened, the flow rate of hot metal slows down in the wide part, so the refining reaction rate improves a little, but the amount of hot metal itself increases in the slow flow part, so it is difficult to contact with the refining agent. The efficiency may deteriorate, and the overall refining efficiency may even become lower. On the other hand, in the present invention, as mentioned above, only the upper side including the slag line at the lance immersion position is widened, and the lower part of the hot metal flow path is not wide, so the hot metal flowing through this flow path is , makes efficient contact with the refining agent injected from the lance. Moreover, the hot metal that is blown upward together with the refining agent due to the bubbling effect that accompanies the injection of the refining agent further contacts the valuable refining agent contained in the slag retained in the slag retention area and undergoes refining, so the refining efficiency increases. significantly enhanced. By the way, the latter half of Fig. 7 shows the case (example) using a hot metal gutter in which only the upper side near the slag line in the lance immersion part is widened to form a slag retention part as shown in Fig. 2, and the lance immersion In the case (comparative example) in which the entire area including the hot metal flow path is widened to form a retention area for hot metal and slag, the elapsed time and desilicating agent are injected from a lance at a rate of 20 kg per ton of hot metal. It is a graph showing a comparison of the relationship between silicon efficiency. As is clear from this graph, it can be seen that according to the present invention, the desiliconization efficiency can be greatly improved compared to the comparative example in which the entire lance immersion position of the hot metal gutter is widened.

The present invention is roughly constructed as described above, but in short, it includes a wide slag retention section formed at a suitable position above the hot metal gutter, and a lance that is immersed with its tip in contact with the hot metal flow path at that position. The gist lies in the following, and as long as such a configuration is provided, the specific shape of the hot metal trough 1, the structure of the lance, the installation method, etc. can be changed as appropriate. For example, the shape of the slag channel formed in the hot metal trough may be rectangular or polygonal in addition to the examples shown in FIGS. 1 and 5. Further, although the lance 2 shown has four nozzles 2a arranged horizontally, the number of holes is not limited at all.

Furthermore, in the conventional example shown in FIGS. 3 and 4, from the jet nozzle 2a provided downward at the tip of the lance 2,
Since the refining agent F is blown in with the carrier gas,
Refractories on the lower surface of the gutter facing the injection position [position C]
However, in the present invention, as shown in FIGS. 1 and 2 above,
Since the ejection nozzle 2a is opened laterally near the tip of the lance, there is no fear that the refractory material on the lower surface of the gutter at the lance immersion position will be intensively eroded. Moreover, in the conventional examples shown in FIGS. 3 and 4, since the lance 2 is cantilevered from above as described above, cracks are likely to occur due to vibrations caused by the impact of the hot metal flow or the impact reaction of the injection of the refining agent. According to the present invention, the tip of the lance 2 is in contact with the lower surface of the gutter so that it is supported on both sides, so the vibrations mentioned above can be suppressed and cracks can be suppressed. The means for abutting and fixing the tip of the lance 2 against the lower surface of the molten pig iron gutter 1 may be engagement or fitting fixation using unevenness or steps, but usually the dead weight of the lance 1 itself (usually 400 ~500Kg) and placing it on the bottom of the gutter can be sufficient to secure it. Furthermore, it is more reliable if a descending force is applied from the upper part of the lance by a lifting device.

Furthermore, although the lance 2 used in the present invention is naturally made of a high-performance refractory material, it does not necessarily have to be made entirely of a refractory material. That is, although the leading edge part that is immersed into the hot metal and the leading edge side to which a large amount of hot metal and slag that are scattered during the refining process adhere, are required to be made of refractory material,
For the upper part, which is not exposed to such high heat, there is no need to use expensive and poorly moldable refractory material. Fig. 6 shows a preferred example of the lance 2 designed with these points in mind. Only the lower part is made of fireproof material 2b, and the upper part is constructed with a water-cooled structure by assembling a steel pipe 2c with a double pipe structure. It is said that
The steel pipe part 2c and the refractory material part 2b are made removable, and only the severely eroded tip is replaced at an appropriate time.The upper steel pipe part 2c is used for a long time, so that the cost required for the lance can be reduced. We are trying to reduce this.

Further, in order to further suppress erosion near the slag line for the hot metal trough 1, it is also effective to provide a cooling structure by burying an air cooling pipe or a mist cooling pipe inside the refractory material.

[Effects of the invention] The present invention is configured as described above, and it not only significantly suppresses erosion of hot metal troughs and lances and extends their lifespan, but also reduces hot metal loss, improves refining efficiency, and further improves smelting efficiency. can enjoy many benefits such as worker safety.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view illustrating a continuous refining apparatus according to the present invention, FIG. 2 is a cross-sectional view corresponding to the line - in FIG. 1, and FIG. 3 is a schematic longitudinal sectional view showing a conventional example.
FIG. 4 is a cross-sectional view corresponding to the - line in FIG. 3, FIG. 5 is a schematic plan view showing another embodiment of the present invention,
Figure 6 is a vertical sectional view of the main part showing a specific example of the lance used in the present invention, and Figure 7 is a case in which desiliconization treatment is performed by widening the entire position where the desiliconizing agent is injected in the hot metal sluice (comparative example). ) and the case where desiliconization is performed using a hot metal trough with a flat width only on the upper side including the slag line (example of the present invention), the relationship between elapsed time and desiliconization efficiency (Si%) is It is a graph shown in comparison. 1...Hot metal trough, 1b...Slag retention section, 2...
Lance, M... Hot metal, S... Refined slag, F...
Refining agent, G... Blowing gas.

Claims (1)

[Scope of utility model registration request] In a continuous molten iron refining device in which a lance for injecting a refining agent is immersed into molten iron flowing in a molten iron gutter, the molten iron gutter is formed above the lance immersion position to be wider than the bottom of the gutter to form slag. A continuous molten iron smelting device comprising a refining agent injection lance which forms a retention part and has a jet nozzle opened sideways from near its tip, and the lance tip is in contact with the lower surface of a molten iron gutter. .