KR100916562B1 - How to recycle dust in an electric furnace - Google Patents

Abstract

The present invention relates to a dust recycling method of an electric furnace, and more particularly, to an increase in the amount of dust generated during the production of molten steel using an electric furnace, an iron recovery rate can be increased, power consumption can be reduced, and steel making time can be shortened. The present invention relates to a dust recycling method.

The dust recycling method of the electric furnace according to the present invention is a dust recycling method of the electric furnace to recycle dust by recovering the iron remaining in the dust after re-injecting the dust generated during the production of molten steel in the electric furnace using a dust input device. To

The dust of the fine particles stored in the hopper is the dust discharged to one side of the inlet pipe by a dust discharge means, the reducing material is introduced to the other side of the inlet pipe, the dust and the reducing material introduced through the inlet pipe The step of combining in the discharge pipe to be simultaneously introduced into the electric furnace and the dust and the reducing material combined in the discharge pipe comprises the step of introducing into the electric furnace through the lance and secondary melting during the molten steel manufacturing process of the electric furnace After the end of the charged scrap metal is characterized in that it is introduced into the electric furnace after 80% to 90% of the time point.

Dust, Furnace, Dust Recycling, Slag, Withdrawal Rate

Description

Method for recycling dust of Electrode Arc Furnace             

1 is a cross-sectional view showing the configuration of a general electric furnace.

2 is a schematic view showing a state in which a dust input device applied to the present invention is installed in an electric furnace.

Figure 3 is a graph showing the relationship between the withdrawal rate and the amount of dust generated according to the change in the particle size of the dust according to the present invention.

<Explanation of symbols for the main parts of the drawings>

100 ... dust feeder 110 ... hopper

120 Dust discharge means 121 Pneumatic motor

122 ... 130

140 ... double input pipe 200 ... electric furnace

210 ... Lance R ... Reducing Materials

The present invention relates to a dust recycling method of an electric furnace, and more particularly, to an increase in the amount of dust generated during the production of molten steel using an electric furnace, an iron recovery rate can be increased, power consumption can be reduced, and steel making time can be shortened. The present invention relates to a dust recycling method.

As a general electric furnace, as shown in FIG. 1, the upper electrode 3, which is an electric conductor, is inserted into the center of the roof 2 located above the main body 1 of the electric furnace, and the scrap metal is passed through the basket or the hopper 8. When a corresponding raw material is charged into an electric furnace, the metal or alloy is heat-treated or melted by arc heat by electricity.

In addition, a lance 5 for introducing oxygen and a reducing material into the electric furnace through the slag door 4 formed on one side of the electric furnace is provided. The lance 5 is made to blow oxygen and reducing material into the inside of the electric furnace, and has an oxygen injection pipe 6 and a reducing material injection pipe 7 therein, and these injection pipes 6 and 7 In order to prevent the molten steel is damaged by the irregular refractory is made to surround. Carbon is applied as the reducing material.

Particulate iron oxides contained in the inputs of scrap metal, etc., which are put into the furnace during the production of molten steel using an electric furnace, are discharged to the outside through a dust collector (not shown) installed in the electric furnace. The dust 10, which is made of cobalt, contains harmful metals such as lead and mercury, and is generally collected and buried in a predetermined place or reused in a steelmaking process.

However, in order to reuse the dust 10 in the steelmaking process, the binder should be added to the dust and solidified, and then put back into the electric furnace. This recycling method has the following problems.

First, when the dust 10 is solidified and introduced into the electric furnace by the hopper 8 located in the upper part of the electric furnace, the solidified dust 10 introduced into the electric furnace is concentrated on one side of the charge so that the solubility of the charge is poor. There is a problem. In this case, the dust 10 having a specific gravity lower than that of molten steel is concentrated in the slag 9 in the upper part of the furnace and coated with the slag 9 to cause an iceberg phenomenon growing in the slag layer. Therefore, dust has a poor contact area with molten steel, so that its solubility is weak, and at the same time, power consumption is increased and production time is delayed to dissolve it.

Second, the dust 10 is introduced into the electric furnace, a large amount is put at a time using a basket or hopper, there is a problem such as deepening the phenomenon of iceberg, reduction of the error rate of the molten steel.

That is, the dust solids are stored in the hopper 8 of about 15 to 20 tons in the upper part of the electric furnace, and the amount of about 1 to 1.5 tons during operation is introduced into the electric furnace through the inlet hole 11. As such, when a large amount of dust 10 is temporarily introduced into an electric furnace, the dissolved state of the dust becomes uneven and grows in the form of iceberg, and these dusts adhere to the refractory and grow and temporarily collapse by the end of operation weight. As the fall occurs, the upper electrode 3 may be damaged or the molten steel may be lost to the outside, thereby reducing the error rate of the molten steel.

Third, in order to process the dust 10 into a solid material, there is a problem in that an additional processing cost such as transportation, molding, and the like, increases manufacturing cost.

On the other hand, another method for reusing the dust 10 in the steelmaking process, there is a method of powder injection of the carbon and dust together with the reducing material into the electric furnace.

However, the above method, by spraying the reducing materials directly into the electric furnace without processing the dust 10 into a solid material, it is possible to reduce the transportation, molding, and additional costs generated in the process of manufacturing the solid material However, in the spraying process, the particulate dust 10 and a part of the carbon are sucked to the duct side of the dust collector installed in the electric furnace, or do not contribute to the reduction of the iron oxide contained in the dust 10, and is introduced into the electric furnace. Reaction with oxygen contributes only to the formation of CO and CO₂ gases, which does not contribute to an increase in iron recovery rate or promotion of dissolution of dust.

The present invention has been made to solve the above problems, the ice recycling phenomenon in the electric furnace is suppressed without processing the recycled dust into a solid material, the dust recycling in the electric furnace is improved iron recovery rate and solubility of the dust To provide a method.

In order to achieve the above object, the present invention, after re-injecting the dust generated during the production of molten steel in the electric furnace into the electric furnace by using a dust input device, to recover the iron remaining in the dust by recycling the dust In the dust recycling method,

The dust of the fine particles stored in the hopper is the dust discharged to one side of the inlet pipe by a dust discharge means, the reducing material is introduced to the other side of the inlet pipe, the dust and the reducing material introduced through the inlet pipe The step of combining in the discharge pipe to be simultaneously introduced into the electric furnace and the dust and the reducing material combined in the discharge pipe comprises the step of introducing into the electric furnace through the lance and secondary melting during the molten steel manufacturing process of the electric furnace After the end of the charged scrap metal is characterized in that it is introduced into the electric furnace after 80% to 90% of the time point.

The features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings. Prior to this, the terms or words used in the present specification and claims are defined in the technical spirit of the present invention on the basis of the principle that the inventor can appropriately define the concept of the term in order to explain his invention in the best way. It must be interpreted to mean meanings and concepts.

Prior to the description of the embodiment looks at the dust input device applied to the dust recycling method of the electric furnace according to the present invention.

As shown in Figure 2, the dust input device 100, the hopper 110 for storing the particulate dust, the stored dust outside the discharge path 122 connected to the lower hopper by the operation of the pneumatic motor 121 Dust discharge means 120 discharged to the, control means 130 for controlling the amount of dust discharged, double input pipe 140 for interconnecting the lance 210 of the discharge path 122 and the electric furnace 200 It is provided.                     

The double input pipe 140 is composed of an inlet pipe 140a, 140a consisting of a double and the discharge pipe 140b is joined to the lance 210 by combining the inlet pipe (140a, 140a). Dust discharged from the dust discharge means 120 flows into one side of the inflow pipe 140a, and the reducing material R flows into the other side. Dust and reducing material (R) introduced through the inlet pipe 140a are combined in the discharge pipe 140b and supplied to the lance 210 so as to be simultaneously introduced into the electric furnace.

Accordingly, the particulate dust stored in the hopper 110 is discharged through the double injection pipe 140 along the discharge path 122 by the signal of the control means 130 that sensed the load of the dust, the double injection pipe Not only can be combined with the reducing material (R) flowing from the inlet pipe 140a of the 140 to be introduced into the electric furnace 200 through the lance 210, it is also possible to control the input time of the dust and its input amount. Do.

In the present invention, the improvement of the withdrawal rate according to the conditions of the dust and reducing material (R) introduced into the electric furnace 200 using the dust input device 100 was verified by the following method.

First, as a reducing material (R) introduced into the electric furnace 200, aluminum having superior oxygen affinity than conventional carbon was employed.

The following formulas (1) and (2) show oxygen affinity for carbon and aluminum, respectively.

C (s) + ½O₂ (g) → CO₂ (g) + 2,750㎉ / ㎏ ---------- (1)                     

2Al (s) + ⅔O₂ (g) → Al ₂ O₃ (g) + 6,759㎉ / ㎏ -------- (2)

As can be seen from the above formulas, it can be seen that the oxygen affinity of aluminum employed in the present invention is superior to that of carbon conventionally used as a reducing material (R). Therefore, when aluminum is added to the electric furnace 200 together with the dust of fine particles, the reduction of iron oxide to iron can be made more efficiently, and the solubility can be improved by the high heat generated in this process.

Second, as shown in Table 1, after reducing the reducing material in each of the operating steps of carbon and aluminum, respectively, into the electric furnace 200, and compared with the iron recovery obtained.

As experimental conditions, after storing two tons of particulate dust, the total amount was put into operation in the electric furnace 200, and the input speed was 100 kg / min, and the input time was limited to 20 minutes. In addition, the reducing material (R) introduced into the electric furnace 200 was charged with powdered carbon and aluminum, respectively.

Here, briefly look at the molten steel manufacturing process of the electric furnace 200, it consists of the operation sequence of primary charging, primary melting, secondary charging, secondary melting, heating and tapping. In particular, since iron recovery is known to be most excellent at the time when 80% to 90% of the charged scrap is dissolved after the secondary dissolution (MD: down), the reducing material (R) is injected after injection of the reducing agent (R). .                     

As shown in Table 1, it can be seen that the iron recovery rate is improved when the powder aluminum having a higher oxygen affinity than the carbon powder is used as the reducing material. In particular, the recovery rate is the highest after the MD group.

This is because, in the first and second dissolving phases, slag of powder-type reducing material R introduced into the electric furnace 200 does not cause reduction with dust by a large amount of oxygen introduced into the electric furnace 200. After deposition on the iron, both iron and carbon recovery were low because it was released to the outside with the slag through the slag door.

On the contrary, when the particulate dust and the powder aluminum are added together after the MD group, the particulate powder dust and the powder aluminum are introduced between the slag bubbles generated in the electric furnace 200 after the MD group, and thus, in the high temperature slag layer. The iron recovery in the slag and the dust contained in the dust can be further promoted to increase the iron recovery.

In addition, since powder dust and powder aluminum are directly injected into the slag layer through the lance 210, dust may be evenly distributed and dissolved throughout the electric furnace 200 due to the flow of slag caused by the gas generated in the molten steel. have. Accordingly, the dust is coated with the slag to prevent the iceberg phenomenon growing in the slag layer, the solubility of the charge is also increased, there is an advantage that the productivity is improved.                     

Third, as shown in FIG. 3, the withdrawal yield and the amount of dust generated according to the change of the particle size of the dust were compared.

The conditions of this experiment were the same as the experimental conditions in Table 1, and the powder aluminum having the best iron recovery rate was used as the reducing material (R), and after the MD group, the powder dust was introduced into the electric furnace 200 and the dust. The particle size of was limited to 5mm or less so as not to block the entrance of the lance (210).

As a result of the experiment, it was found that as the particle size of the electric furnace 200 increases, the iron recovery rate increases and the amount of dust generated decreases. On the other hand, when the particle size is 2mm or less, the specific gravity of the dust itself is low, the iron is not reduced in the slag layer, the dust itself is released to the outside by the dust collector in the electric furnace 200, the dust generation amount of the dust collector is increased. Accordingly, the appropriate particle size of the powder aluminum and the dust introduced into the lance 210 is preferably 2 mm to 5 mm in a range that does not block the inlet of the lance 210.

Table 2 compares the operation results of the prior art and the present invention based on the results of the above experiment.

Item Prior art Invention Dust input method Bulk feed through hopper or basket Continuous input method through lance Dust and reducing state Solids Powder (particulate) Granularity 20-30mm 2-5mm Dust utilization 10kg / ts 15kg / ts Iron recovery 90.4% 92.3% Power source 430 kwh / ts 415kwh / ts Steelmaking time 63 minutes / ch 61 minutes / ch Hourly productivity 131.4ton / hr 135.7ton / hr

Looking at the results of the operation so far as shown in Table 2, it can be seen that not only the amount of power reduction compared to the conventional, but also the iron recovery rate is improved, the steelmaking time is shortened, thereby improving the productivity per hour. In addition, the dust utilization amount was also increased by improving the solubility through the aluminum reducing material (R).

Thus, in the present invention, based on the results of the above experiments, the particle size of the dust and reducing agent (R) is formed into a powder of 2 ~ 5mm, when recycling continuously after the MD group, the recycling degree of dust The result was excellent.

According to the dust recycling method of the electric furnace of the present invention configured as described above, the withdrawal yield by introducing the dust and aluminum reducing material in the fine powder state without a separate process such as conventional solidification during the production of molten steel in the electric furnace As well as the increase of the amount of dust used at the same time, the amount of power can be reduced and the steelmaking time can be shortened, thereby improving productivity.

In addition, an increase in the amount of dust used leads to a reduction in the amount of landfill of the dust, thereby realizing environmentally friendly operation.

Claims (1)

In the electric furnace recycling method of recycling the dust by re-injecting the dust generated during the production of molten steel in the electric furnace into the electric furnace using a dust input device, by recovering the iron remaining in the dust, The dust of the particulate stored in the hopper is discharged to the one side of the inlet pipe by the dust discharge means; Reducing material is introduced to the other side of the inlet pipe; The dust and the reducing material introduced through the inlet pipe are combined in an outlet pipe so as to be simultaneously introduced into an electric furnace; And The dust and the reducing material combined in the discharge pipe includes a step of being introduced into the electric furnace through a lance and when the scrap metal is 80% to 90% dissolved after the secondary melting of the molten steel manufacturing process of the electric furnace The dust recycling method of the electric furnace, characterized in that it is introduced into the electric furnace after.

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