JP2737606B2 - Recovery method of zinc-containing dust by hot metal refining - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering zinc-containing dust generated in a hot metal refining process.

[0002]

BACKGROUND ART Galvanized steel is old is called tin, mainly roofing, building materials and such outside wall, used for convenience goods buckets, etc., further, such as chromate treatment and phosphate treatment in recent years With the advent of chemical conversion treatment and alloying treatment galvanized steel sheet, the quality level has been greatly improved, and it is widely used in automobiles, electric appliances, civil engineering and the like. For this reason, in recent years, the consumption of scrap containing zinc has increased dramatically in the steelmaking process along with an increase in the demand for galvanized steel sheets. When zinc containing scrap 22 is used in a steelmaking process, for example, as shown in FIG. 3, in a converter 21 refining, zinc evaporation occurs at a low temperature near 700 ° C. A part of zinc is recovered together with the dust 23 at the time of charging the hot metal, but it is completely removed after scrap melting at the initial stage of the blowing. It is impossible to separate and collect the dust up to. Reference numeral 25 denotes an oxygen gas blowing lance.

[0003] Zinc concentrations in the zinc-containing dust recovered in the converter refining is about 1-2%, to recovered zinc in the zinc-containing dust, too uneconomical der
You. Conventionally, in converters and electric furnaces, smelting dust mainly composed of iron oxide when an iron source containing no zinc is used is often mixed with sintering raw materials and reused in a blast furnace. If the contained dust is mixed with the sintering raw material and reused in a blast furnace, the furnace condition of the blast furnace becomes unstable, and thus the dust has been disposed of as landfill. However, disposal of zinc-containing materials is not only an environmental problem, but also has a cost disadvantage of trashing a large amount of iron source. Under such circumstances, the treatment of zinc that evaporates at a temperature lower than the melting temperature of steel is becoming a major problem with respect to environmental problems and waste recycling costs.

Recently, there has been a movement to reuse this zinc-containing dust. However, it is difficult to remove zinc from a large amount of zinc-containing dust. However, this requires complete replacement of the dust collection equipment, which not only requires a large capital investment, but also has the disadvantage that there is a cost disadvantage to wet dust collection. I have.

[0005] As a method of treating zinc-containing dust recovered in the converter refining, a method of treating zinc-containing dust with an acid to dissolve and remove the contained zinc component (Japanese Patent Application Laid-Open No. 49-1979).
No. 31527), a steel scrap is heated to about 907 to 1250 ° C. in a pre-refining furnace under a reducing atmosphere having a CO2 / CO molar ratio of <0.004 to liquefy tin in the scrap and vaporize zinc. In addition to lowering the liquid tin through the steel material to remove and collect it from the lower part of the furnace, waste gas containing vaporized zinc is led into the condensing device, and the temperature is reduced to a temperature below the boiling point of zinc under the same atmosphere composition as in the pre-refining furnace. A method of liquefying and removing and recovering zinc by cooling (Japanese Patent Laid-Open No.
No. 5609), a high zinc-containing material is selectively collected from a time zone having a large amount of generated zinc from other time zones, and a high zinc-containing material is selectively collected. The high zinc-containing material has a carbon content of 5 to 16% by weight. A powdered combustible carbon material is blended so that the average diameter is 2
The pellets are granulated into pellets of ８8 mm, and the pellets are laid on the ignition layer previously formed on the grate to a thickness of 150 to 350 mm and 0.05 to 0.25 (m ³ / kg pellet).
A method of sintering the pellets while reducing and roasting them under the upward air flow (Japanese Patent Laid-Open No. 59-1611) has been proposed.

[0006]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Laid-Open No. 49-31 is disclosed.
The method disclosed in Japanese Patent No. 527 treats zinc-containing dust with an acid and dissolves and removes the zinc content. Therefore, unless the zinc content in the zinc-containing dust is increased to a high concentration , the processing cost increases and the economy increases. Does not hold. Also, Japanese Patent Application Laid-Open
The method disclosed in Japanese Patent No. 5609 discloses a method in which waste gas containing vaporized zinc is introduced into a condensing device, cooled and liquefied, and collected. It is necessary to install a condensing device in front of the current dust collector. Requires significant capital investment. Further, Japanese Unexamined Patent Publication No.
The method disclosed in Japanese Patent Application No. -1611 has a problem that the furnace state of the blast furnace becomes unstable when it is used in a blast furnace because the collected high zinc-containing material is used as a sintering raw material.

An object of the present invention is to use two refining furnaces.
In the hot metal refining process, galvanized steel sheets were used as a steel scrap source in the first dephosphorization and desiliconization processes , and exhaust gas dust was collected.
It is an object of the present invention to provide a method for economically recovering das as high-concentration zinc-containing dust .

[0008]

Means for Solving the Problems The present inventors have conducted various tests and studies to achieve the above object. As a result, one of the hot metal refining processes using two
When refining using a small amount of oxygen gas as in the base dephosphorization and desiliconization processes, by dissolving iron sources such as zinc-containing scraps such as galvanized steel sheets, high levels of ability to recover all the zinc concentration, and investigate the ability to substantially zero zinc concentration in the dust generated in the later converter refining in the process is al, have reached the present invention.

That is, the present invention relates to a first dephosphorization and desiliconization.
Hot metal refinement using two refining furnaces in the process and the second decarburization process
In smelting process, dephosphorization by the first corresponds a refining furnace, charged with zinc-containing scrap in molten iron as de珪工blows small amount of oxygen gas, dephosphorization free of zinc and completely evaporated zinc , along with obtaining a desiliconization been molten iron, a method of recovering zinc-containing dust by the hot metal refining and recovering a high concentration of zinc-containing dust.

[0010]

[Action] In the present invention, soluble using refining furnace 2 group
In pig iron refining process, dephosphorization by the first corresponds a refining furnace, charged with zinc-containing scrap in molten iron as de珪工blows small amount of oxygen gas, does not contain zinc completely evaporated zinc de phosphorus, from getting a desiliconization been hot metal, dephosphorization, rather small, the amount of dust itself that occurs in about de 珪工, moreover zinc content in the dust and 9-15% compared to 1-2% of the prior art Very high. Accordingly, the first corresponds a dust collection facility, by number provided separately for each refining furnace 2 groups th 1
Dust having a high zinc content generated in the base dephosphorization and desiliconization steps can be collected. In addition, the zinc concentration in dust generated in the second refining furnace in the subsequent process can be made almost zero, and can be reused as an iron source.

[0011] In the present invention, the hot metal temperature in the dephosphorization and desiliconization steps in the first refining furnace is preferably 1100 to 1500 ° C, and if it is less than 1100 ° C, it is difficult to dissolve the zinc-containing iron source. If it exceeds 3, the dephosphorization property is remarkably reduced, and the intended purpose cannot be achieved. The amount of oxygen gas sprayed in the dephosphorization and desiliconization steps by the first refining furnace is 0.1 to
3.5 Nm ³ / min · t is preferable, and 0.1 Nm ³ / m
If it is less than int, the dephosphorization and desiliconization reactions of the hot metal are not sufficient,
On the other hand, if it exceeds 3.5 Nm ³ / min · t, the amount of decarburization increases and the heat source in the decarburization step becomes insufficient.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 The details of the present invention will be described below with reference to FIG. FIG. 1 is an explanatory view of a process embodied by applying to hot metal dephosphorization and desiliconization using a converter. In FIG. 1, 1 is a dephosphorization and desiliconization furnace, 2 is an oxygen gas blowing lance,
Numeral 3 denotes a zinc-coated steel sheet scrap, and 4 denotes zinc-containing dust. The zinc-coated steel sheet scrap 3 introduced into the dephosphorization and desiliconization furnace 1 is brought into contact with hot metal and melts. All of the zinc fume is vaporized and evaporated and is collected as zinc-containing dust 4 by a dust recovery device for a dephosphorization and desiliconization furnace 1 (not shown) together with dust generated by blowing a small amount of oxygen gas from an oxygen gas injection lance 2. You. 5 is a decarburization furnace
The hot metal dephosphorized and desiliconized in the dephosphorization and desiliconization furnace 1 is charged. 6 is an oxygen gas blowing lance, 7 is dust containing almost no zinc, and the dephosphorized and desiliconized hot metal is supplied to a decarburizing furnace 5.
The degassing process is performed while being stirred by the oxygen gas blown from the oxygen gas blowing lance 6, and the generated dust 7 containing almost no zinc is collected by a dust collecting device for the decarburizing furnace 5 (not shown). .

With the above configuration, FIG.
As shown in the figure, hot metal refining in the dephosphorization and desiliconization furnace 1 using a converter
Zinc-containing dust amount generated A when refining is shown in normal 3
To 1 group converter blowing at less than 10% and less of B, moreover, since almost all of dephosphorization, zinc contained in a galvanized steel sheet scrap 3 charged into the de珪炉1 is recovered, in the dust Has a very high zinc content of 9 to 15%. Moreover, dust 7 generated by decarburization furnace 5, dephosphorization, because zinc galvanized steel scrap 3 with de珪炉1 is nearly all vaporized evaporated to remove the zinc content Ri substantially zero and Do, Even when the blast furnace is reused as a sintering raw material, the blast furnace can be reused without becoming unstable.

Example 2 Two 160 Ton / charge converters were used, and the first converter was used as a dephosphorization and desiliconization furnace.
5 Ton is put into 150 Ton of hot metal, and oxygen gas 20
Dephosphorization while blowing 0 nm ³ / min, After desiliconization treatment, dephosphorization in the converter for decarburization 2 groups th charged with desiliconization treated molten iron while blowing an oxygen gas 350 Nm ³ / min de Dust discharged from each converter after charcoal treatment was collected by each dust collection device, and the amount of generated dust and the zinc content in the dust were measured. Table 1 shows the results. For comparison, a converter of 160 Ton / charge was used as a conventional method, and 1.5 Ton of zinc-containing scrap was
It was charged into Ton and blown while blowing oxygen gas at 350 Nm ³ / min, and the discharged dust was collected by a dust collecting device, and the amount of generated dust and the zinc content in the dust were measured. The results are shown in Table 1.

[0015]

[Table 1]

As shown in Table 1, according to the method of the present invention, zinc-containing dust recovered from a dephosphorization and desiliconization furnace and dust containing almost no zinc recovered from a decarburization furnace were added in an amount ratio of 1%. : Recovered in a ratio of 12 . With this, 9 of all dust
Since 3% contains almost no zinc, it can be reused as a raw material for sintering without zinc extraction treatment . On the other hand, in the conventional method, the zinc content in the collected dust was 1.2%, and it was impossible to reuse it as a sintering material without zinc extraction treatment.

[0017]

As described above, according to the present invention, according to the present invention method, the zinc-containing dust produced by the dissolve of scrap containing zinc can be recovered with a small amount and high zinc content, refining and reducing the zinc recovery costs Dust can be reused.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a process embodied by applying the present invention method to hot metal dephosphorization and desiliconization methods using a converter.

FIG. 2 is a graph showing a relationship between blowing time and dust generation amount during hot metal pretreatment A and converter blowing B;

FIG. 3 is an explanatory view of a conventional converter blowing process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dephosphorization and desiliconization furnace 2, 6, 25 Oxygen gas injection lance 3 Galvanized steel sheet scrap 4 Dust containing zinc 5 Decarburization furnace 7 Dust containing almost no zinc 21 Converter 22 Scrap containing zinc 23 Dust 24 Dust recovery system

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mitsunobu Sato 4-5-33 Kitahama, Chuo-ku, Osaka City, Osaka Prefecture Inside Sumitomo Metal Industries, Ltd. (72) Inventor Go Okada 1850 Minato, Wakayama-shi, Wakayama Sumitomo Metal Industries Inside Wakayama Works (56) References JP-A-6-264126 (JP, A)

Claims (1)

(57) [Claims] 1. A first dephosphorization and desiliconization step and a second decarburization
In the hot metal refining process using two refining furnaces,
Contains zinc in hot metal in dephosphorization and desiliconization processes in the base smelting furnace
Charged with scrap blows small amount of oxygen gas, dephosphorization free of zinc and completely evaporated zinc, along with obtaining a desiliconization been hot metal, and wherein recovering the high concentration of zinc-containing dust recovery How <br/> method of zinc-containing dust by the hot metal refining to.