WO2008032638A1

WO2008032638A1 - Method of recycling zinc-containing converter dust

Info

Publication number: WO2008032638A1
Application number: PCT/JP2007/067421
Authority: WO
Inventors: Hiromichi Takesue; Masaru Sadachika; Saburo Sato
Original assignee: Astec Irie Co., Ltd.
Priority date: 2006-09-14
Filing date: 2007-09-06
Publication date: 2008-03-20
Also published as: CN101144122B; CN101144122A; JPWO2008032638A1; JP4750846B2

Abstract

A method comprising: a first step in which coarse particles are separated from a converter dust recovered with a wet type dust collector to obtain a zinc-containing fine-particle dust having a zinc content of 0.5-10 mass% and an iron content of 50-90 mass%; a second step in which the dust is separated by a water cyclone (15) into a low-zinc-content medium-fine-particle dust having an average particle diameter of 8-25 µm and a zinc content of 1 mass% or lower and a high-zinc-content microfine-particle dust having an average particle diameter of 1-5 µm and a zinc content higher than 1 mass% and containing more iron oxide than the medium-fine-particle dust; a third step in which the medium-fine-particle dust, without undergoing a zinc elimination treatment, is mixed with a binder and pressed to form a mass for use as a converter feed material or electric-furnace feed material; and a fourth step in which the microfine-particle dust is dried and subsequently subjected to a zinc elimination treatment and the resultant dust is used as it is as a blast-furnace feed material or is converted to a mass for use as a converter feed material.

Description

Specification

Recycling method of zinc-containing converter dust

Technical field

[0001] The present invention divides the zinc-containing converter dust generated in the converter process during the production of steel into a dust component with a low zinc content and a dust component with a high zinc content, and efficiently recycles it into a blast furnace, converter or electric furnace. The present invention relates to a method for recycling zinc-containing converter dust.

Background art

[0002] The production volume of zinc-plated steel sheets used in automotive steel sheets has increased rapidly over the past 10 years, and along with that, the amount of zinc-plated steel sheet scraps put into a converter and melted and reused is also increasing. It has increased. Therefore, much zinc is contained in the dust generated from the converter.

Conventionally, converter dust recovered by an exhaust gas recovery system (OG recovery system) for non-combustion converters has been recycled as blast furnace raw material through a sintering process. Blast-furnace recycling of such converter dust can be performed without problems for converter dust with a low zinc content (1% by mass or less). However, as described above, when converter dust having a high zinc content is used as a blast furnace raw material, there is a problem of causing operational troubles such as shelves.

In addition, if the entire amount of converter dust generated from a power converter, in which zinc-containing converter dust is partially recycled to the converter, is input to the converter, the zinc content in the converter dust generated again is reduced. When the concentration progresses and exceeds the limit concentration (which is said to be about 8% by mass) that ultimately affects the molten steel components, there is a problem that recycling to the converter becomes difficult.

[0003] Therefore, fine dust containing zinc is disposed of in landfill despite the high iron content (about 70% by mass). However, it is said that landfill disposal will not be possible in the near future due to soaring landfill disposal costs.

Under these circumstances, proposals have been made regarding a dezincification method for separating and recovering zinc in converter dust. Fig. 4 shows an example of a conventional dezincification method for converter dust. A zinc-containing converter that was collected in the collected water by a non-combustion dust collector 41 provided above the converter. The strike is conveyed to the coarse particle separator 42, where coarse particles having a large particle size (coarse dust) are separated. The zinc-containing fine dust that has passed through the coarse separator 42 is concentrated by the thickener 43 and then dehydrated by the filter press 44. The zinc-containing fine dust thus obtained is subjected to drying treatment 45, molding 46, and dezincing treatment 47. The dezincing treatment 47 is performed, for example, by reducing iron oxide in the dust at 1100 to 1300 ° C in a rotary reduction furnace and simultaneously reducing the contained zinc and separating and recovering the vaporized metallic zinc (for example, Japan). (See Japanese Laid-Open Patent Publication No. 2001-294942). The converter gas discharged from the non-combustion dust collector 41 is accumulated in the gas holder.

[0004] The above-described conventional method for dezincing converter dust has high dezincing efficiency, and iron oxide in the converter dust is also reduced at the same time. Therefore, converter dust can be recycled in a blast furnace or converter. Convenient.

However, it has a problem that it requires a lot of equipment construction costs and high processing costs.

Yes

In addition, in the previous stage of the dezincing process, low zinc content that can be recycled in a blast furnace or converter without dezincing process is collected at low cost and selectively from converter dust. If this can be achieved, it is possible to reduce the amount of converter dust that is the target of dezincing treatment, and thus it is possible to reduce the size of dezincing treatment equipment and reduce treatment costs.

[0005] Therefore, for example, Japanese Patent Laid-Open No. 2004-122024 and Japanese Patent Laid-Open No. 2005-21841 propose a method for separating zinc dust from converter dust with low zinc content! It has been.

In Japanese Patent Laid-Open No. 2004-122024, wet cyclones with different classification performance are provided in at least two stages in series, and slurry containing converter dust is separated into overflow and underflow by the previous wet cyclone. Thereafter, a method is disclosed in which this underflow is further separated into an overflow and an underflow by a subsequent wet cyclone. This pre-stage wet cyclone can capture only dust with large particles in the slurry by underflow, thus avoiding the risk of piping clogging without increasing the solid fraction of underflow. In addition, by treating the separated underflow with a subsequent wet cyclone, more than half of the zinc is recovered on the overflow side, while most of the iron is removed. Since it is collected in the underflow, zinc and iron in the slurry can be separated efficiently.

[0006] At this time, the dust in the underflow separated by the subsequent wet cyclone is reused as a sintering raw material. However, the use of recovered dust cannot be further expanded without mentioning that it is reused as another raw material, ie, converter raw material or electric furnace raw material. This is thought to be due to the fact that further processing is necessary to reuse the collected dust as converter raw material or electric furnace raw material, and the processing conditions are not in place at present.

For example, if the dust is simply dried, it takes time to remove the moisture, resulting in a reduction in dust processing efficiency. Even if the drying process is performed, if the entire amount is charged into a converter or an electric furnace as it is, the amount of dust scattered increases and the working environment deteriorates.

Here, in order to increase the dust processing efficiency, it is conceivable to shorten the time required for the drying process. In this case, however, steam explosion may occur when charging the converter or electric furnace.

For this reason, when the amount of dust collected in the future increases and exceeds the amount that can be reused as a sintering raw material, as described above, landfill processing must be performed.

[0007] Further, Japanese Patent Application Laid-Open No. 2005-21841 discloses a slurry containing converter dust, a slurry containing dust having a high zinc content and a slurry containing dust having a low zinc content by a wet separation device. Is disclosed.

However, since this method is a method of obtaining zinc product raw materials and metal raw materials from converter dust, before separating the slurry containing converter dust with a wet separator, the pH of the slurry is adjusted, The yield is increased. Thus, since it is not a method of actively removing zinc from the slurry, a large amount of zinc may remain in the separated dust having a low zinc content.

Therefore, there is a problem in using it as a raw material for a blast furnace, converter, or electric furnace without dezincing the separated dust having a low zinc content.

[0008] The present invention has been made in view of the power and the circumstances, and is generated in the converter process during the production of steel. It is possible to reduce the cost required for the dezincing process by separating the zinc-containing converter dust into low dust content and high dust content and efficiently recycling them to a blast furnace, converter or electric furnace. It aims to provide a method for recycling zinc-containing converter dust.

Disclosure of the invention

[0009] In the method for recycling zinc-containing converter dust according to the present invention in line with the above object, the coarse particles are separated from the converter dust collected by the wet dust collector, and the zinc content is A first step of obtaining fine lead-containing dust containing 5 mass% or more and 10 mass% or less and having an iron content of 50 mass% or more and 90 mass% or less;

The zinc-containing fine-grained dust is produced by a hydrocyclone, and the average particle size is in the range of 8,1 to 25 m, and the zinc content is 1% by mass or less. Average particle size Force S l ^ m or more and 5 111 or less, high zinc content fine dust containing more than 1% by mass of zinc and containing more iron oxide than the above fine dust A second step of separating into

The intermediate fine dust is not subjected to dezincing treatment, and is added with a binder to be agglomerated for use as a converter raw material or an electric furnace raw material by pressing, and a third step;

The fine dust is dried and then dezinced and used as it is as a blast furnace raw material or as agglomerated material as a converter raw material.

[0010] The zinc-containing fine-grained dust described above is obtained by trapping and solidifying gaseous metallic zinc on the surface of the fine-grained dust. This is because metallic zinc has a low boiling point and therefore exists in a gaseous state in the converter. For this reason, the zinc-containing fine particle dust has a smaller zinc particle size, and the higher the ratio of the surface area to the mass, the higher the zinc content. In addition, by classifying zinc-containing fine dust with a hydrocyclone, it becomes possible to separate into medium fine dust having a large average particle size and fine dust having a small average particle size. For this reason, the separated medium fine dust becomes low-zincaceous (zinc content is 1% by mass or less) and can be recycled without dezincing treatment.

[0011] In addition, the zinc-containing fine-grain dust has an oxide film formed on its surface as oxygen permeates from the surface. Note that the thickness of the oxide film is almost equal regardless of the particle size under the same conditions. It becomes constant. For this reason, in the zinc-containing fine dust, the particle size of the fine dust becomes small, and the content ratio of iron oxide increases as the ratio of the surface area to the mass increases. Therefore, fine grain dust contains more iron oxide than medium fine dust.

In this way, the medium fine dust has a high metallic iron content and low zinc content, so it can be recycled as a converter raw material or an electric furnace raw material after it has been agglomerated, so it can be recycled in a blast furnace. Rather than doing so, it is possible to reduce energy costs.

[0012] When producing agglomerates from medium fine dust, the medium fine dust is pressed at high pressure and a binder is added to the medium fine dust, maintaining the shape when agglomerated. it can. As a result, workability at the time of transporting the agglomerates is improved, and it is possible to reliably prevent dangers such as a steam explosion and dust scattering when charging into the converter or electric furnace. Medium-fine dust can be agglomerated for use as converter raw material or electric furnace raw material by adding a binder without dezincing treatment and pressing it. Cost can be reduced.

On the other hand, with regard to fine-grained dust, the power to perform dezincing treatment Medium-fine grained dust that does not require dezincing treatment has been separated in advance, so the amount of processing is reduced and the processing cost required for dezincing treatment is reduced. I can plan.

[0013] In the method for recycling zinc-containing converter dust according to the present invention !, a part of the medium fine dust separated in the second step is dried without dezincing treatment. It is preferably used as a blast furnace raw material.

Thus, by drying the medium fine dust and using it as a blast furnace raw material, the processing efficiency of the medium fine dust that does not need to be agglomerated can be improved.

[0014] In the method for recycling zinc-containing converter dust according to the present invention, the press treatment in the third step is performed so that the water content of the medium fine dust separated by the hydrocyclone is 10% by mass or more and 15% by mass. It is preferable that the agglomerate is prepared by adjusting to the following, adding the binder and kneading, and then placing the mixture in an extrusion-type press apparatus and extruding under pressure. In this way, the moisture content of the medium fine dust is adjusted to 10% by mass or more and 15% by mass or less, so that the moisture content of the medium fine dust is reduced and agglomeration using a simple extrusion press is possible. Become capable.

[0015] In the method for recycling zinc-containing converter dust according to the present invention, the press treatment in the third step is performed so that the water content of the medium fine dust separated by the hydrocyclone is 30% by mass or more and 60% by mass. It is preferable to produce the plate-like agglomerate by adjusting with the following, adding the binder and stirring, and then molding with a high-pressure filter press squeezed at a pressure of 5 MPa to 20 MPa.

In this way, the medium fine dust whose water content is adjusted to 30% by mass or more and 60% by mass or less is sent to the high pressure filter press, so that the filling operation of the medium fine dust to the high pressure filter press can be carried out smoothly.

In addition, since the medium fine dust has good dewatering efficiency, when the medium fine dust is compressed with the high pressure filter press, the fine dust is separated! / ,! and the fine dust is removed with the high pressure filter press. Compared with the treatment, the moisture content of the dehydrated cake can be lowered, the agglomerates can be densified, the powdering rate can be reduced, and the efficiency of the recycling work can be improved. Furthermore, a binder is added to the medium fine dust! /, So the shape when agglomerated can be maintained.

[0016] In the method for recycling zinc-containing converter dust according to the present invention !, a part of the medium fine dust separated in the second step is not dezinced and is directly dried after drying. It is preferable to use a raw material for a converter or an electric furnace.

Here, the medium fine dust separated by the hydrocyclone has a property close to that of coarse dust with a high content of metallic iron with a low zinc content. Therefore, it contains metal iron at a higher content than medium fine dust, and it can treat medium fine dust in the same way as coarse dust currently used effectively in applications such as recycling. .

Therefore, compared with the conventional recycling in a blast furnace with dezincing treatment, the power S can be greatly reduced.

Brief Description of Drawings

[0017] FIG. 1 is a schematic view of a lead-containing fine-grain dust separator used in a method for recycling zinc-containing converter dust according to an embodiment of the present invention.

[FIG. 2] (A) and (B) are schematic process diagrams of the third process of the method for recycling zinc-containing converter dust, respectively. FIG. 3 is a schematic process diagram of a third process and a fourth process according to a modification.

FIG. 4 is an explanatory view showing a conventional method for dezincing zinc-containing converter fine-grained dust. BEST MODE FOR CARRYING OUT THE INVENTION

[0018] Next, with reference to the accompanying drawings, an embodiment of the present invention will be described for understanding of the present invention.

As shown in FIGS. 1 to 3, the method for recycling zinc-containing converter dust according to one embodiment of the present invention includes zinc-containing converter dust (hereinafter simply referred to as converter dust) recovered by a wet dust collector. 1) to obtain zinc-containing fine dust from the second step, and to separate this zinc-containing fine dust into low-zinc medium fine dust and high-zinc fine dust, It has a third step of agglomerating the separated medium fine dust without dezincing, and a fourth step of dezincing the separated fine dust. This will be described in detail below.

[0019] First, the first step will be described.

Zinc-containing converter dust discharged from the converter (not shown! /,) Charged with zinc-containing scrap is collected together with the generated OG gas in a wet dust collector, where OG gas is a gas component. Are separated. This wet dust collector is a non-combustion type power installed in the upper part of the converter.

Then, the collected water containing the zinc-containing converter dust collected by the wet dust collector is transported to the coarse-grain separator via the soot. This coarse particle separator is designed to collect particles having a relatively high specific gravity and a large particle size (coarse particles). Particle size distribution: about 40-200 am, average particle size: about 100 ^ m)

Yes

[0020] The zinc-containing fine dust obtained by separating the coarse particles with a coarse separator has a zinc content of 0.5 mass% or more and 10 mass% or less, and an iron content of 50 mass% or more. 90% by mass or less. Note that zinc-containing fine dust particles with a zinc content of less than 0.5% by mass can be recycled in a blast furnace without dezincing treatment. On the other hand, the zinc content of zinc-containing fine dust does not exceed 10% by mass.

In addition, the particle size distribution of the zinc-containing fine dust is, for example, about 0 · !!-80 m, and the particle size is 10

以下 m or less account for 80% of the total mass. Thus, zinc-containing fine-grained dust has a higher zinc content than conventional converter dust, and a higher iron content than blast furnace dust.

As shown in FIG. 1, the collected water containing the fine zinc-containing dust is further supplied to the thickener 10 to be concentrated and processed into a slurry, and then the first slurry receiving tank 12 is supplied by the pressure pump 11. Sent to.

[0021] Next, the second step will be described.

The zinc-containing fine-grain dust in the slurry sent to the first slurry receiving tank 12 is a first mechanical stirrer provided in the first slurry receiving tank 12 and having a stirring blade and a motor for driving the stirring blade. Stirred by 13 and uniformly dispersed in the first slurry receiving tank 12.

The treated product in which the zinc-containing fine dust is dispersed is conveyed to a water cyclone (also referred to as a liquid cyclone) 15 by a first slurry pump 14. Then, the zinc-containing fine dust in the treated product is separated into a low-zinc medium fine dust and a high-zinc fine dust by the hydrocyclone 15. The hydrocyclone 15 is a conventionally known one, and separates the fine lead-containing fine dust into medium fine dust and fine dust using centrifugal separation.

[0022] The separated medium fine particle dust has an average particle size in the range of 8 111 to 25 111 (for example, the particle size distribution is about 5 to 80 111), and the zinc content is 1% by mass. (Preferably 0.5% by mass) or less.

Fine-grained dust has an average particle size in the range of 1 m to 5 m (for example, a particle size distribution of about 0.1 to 20 111), and the zinc content exceeds 1% by mass (medium fine). When the content of zinc in the granular dust is 0.5% by mass or less, it exceeds 0.5% by mass), and contains more iron oxide than the medium fine dust.

[0023] Most of the fine particle dust separated by the hydrocyclone 15 is recovered from the overflow pipe 16, and most of the medium fine particle dust is recovered from the underflow pipe 17.

Here, Table 1 shows the analysis results of the dust collected from the overflow pipe 16 and the dust collected from the underflow pipe 17. The results of this analysis are based on a classification test (d 2011) using a WARMAN 6C hydrocyclone (spigot diameter 30 mm) as the hydrocyclone and the pump (first slurry pump) flow rate at 0.4 m ³ / min. m) [0024] [Table 1]

[0025] In Table 1, "M-Fe" represents metallic iron and "T Fe" represents total iron.

As is clear from Table 1, the hydrocyclone 15 underflow pipe 17 has 70% by mass of particles with a particle size exceeding 20 111, and the zinc content is 0.5% by classification with hydrocyclone 15 The dust with a low content of 70% by mass and metallic iron content of 70% by mass is separated and recovered. Also, from the overflow pipe 16 of hydrocyclone 15, the particle size is less than 20 in by classification with hydrocyclone 15. High-zinc dust that contains mainly particles and has a zinc content exceeding 1% by mass is separated and recovered!

[0026] As described above, the dust having a large particle size has a small amount of zinc attached, while the dust having a small particle size has a large amount of zinc attached.

Here, the results of an investigation on the relationship between the size of the particle size and the amount of zinc adhered will be described. In the test, zinc-containing fine dust (zinc content 2.46%), which was collected from the converter by a wet dust collector and separated by a coarse separator, was used after drying. did. Then, the dried product was classified into a particle size of 20 m or more and less than 20 m by a sieve classification method, and the mass distribution ratio and the zinc content were analyzed.

The results of this analysis are shown in Table 2.

[0027] [Table 2] Particle size Mass Self-rate ¾ ^ Proportion

2 0 mu full 8 5% 2.8 mass ^_0/0

2 0 μ πι least 1 5 mass ^_0/0 0.4 mass ^_0/0

[0028] As is apparent from Table 2, the zinc content of the zinc-containing fine dust having a particle size of 20 Hm or more is 0.4% by mass, while that of the zinc-containing fine dust having a particle size of less than 20 in. The zinc content was 2.8% by mass.

This result corresponds to the overflow and underflow forces shown in Table 1, and the zinc content of each dust obtained.

In other words, it was confirmed that the amount of zinc attached to the dust having a large particle size was small, and that the amount of zinc attached to the dust having a small particle size was large!

[0029] From the above, the medium fine dust has a zinc content of 1% by mass or less, and the zinc contained does not affect the molten steel components in the converter. It can be used for converter recycling or electric furnace recycling.

However, medium fine dust has a high moisture content (about 30% by mass), and if it is inserted into a converter or electric furnace without drying, it may cause a steam explosion or abnormal combustion. In addition, since the medium fine dust has a small average particle size, it may be pulverized and scattered when it is charged into a converter or electric furnace in the state of fine particles. For this reason, after adding a binder to the medium fine dust and making it into an agglomerate by press treatment, it is charged into a converter or electric furnace.

Hereinafter, the third step of performing the agglomeration treatment of the medium fine dust will be described with reference to FIGS. 2 (A) and 2 (B).

[0030] The slurry-like medium fine dust recovered from the underflow pipe 17 of the hydrocyclone 15 is conveyed to a stirring rotary dryer and kneaded with a binder as shown in Fig. 2 (A). . The kneaded product of the medium fine dust and the binder is dried until the water content becomes about 10% by mass or more and 15% by mass or less, and then put into an extrusion press. Then, it is pressure-extruded by an extrusion-type press device, further dried as necessary, and agglomerated. The The water content of the above-mentioned medium fine dust may be adjusted before adding the solder, or may be adjusted after adding the binder.

The agglomerate (dust cake) thus obtained is charged into the converter as a converter raw material through, for example, a scrap chute. Moreover, it is charged into the electric furnace as the electric furnace raw material.

[0031] Here, the shape and size of the agglomerate, the type and addition amount of the binder, the agglomeration conditions such as the pressing pressure are not particularly limited as long as pulverization can be suppressed during charging into the converter or electric furnace. .

In addition, for example, cement, lime, bentonite, etc. are used as the binder, and this is added, for example, to about 5% by mass of medium fine dust, and the press pressure is set to 5 MPa, so that the powdering rate is 5 mass% or less. Can be suppressed.

In addition, the moisture content of the agglomerate must be kept below a certain level in order to prevent steam explosion and abnormal combustion during charging into the converter or electric furnace. For example, when the amount of agglomerate charged into a 300-ton converter is 1 ton or less per time, the 1S charge that can be used as it is after pressing exceeds 1 ton per time Further drying is required.

In addition, although the above-described extrusion-type press apparatus is a conventionally well-known apparatus which extrudes a kneaded material from an opening part, it is not limited to this.

[0032] In addition, the slurry-like medium-sized dust collected from the underflow pipe 17 of the hydrocyclone 15 is conveyed to a slurry tank (not shown) in the form of a slurry as shown in FIG. 2 (B). , water content 60 wt% or less than 30% by mass here (preferably, the lower limit 40% by mass, still more 4 5 mass ^_0/0, the upper limit 55 mass ^_0/0) is hydrolyzed to become. This slurry-like medium-sized dust is further mixed with a binder (for example, about 5 to 15% by mass), stirred, conveyed to a high-pressure filter press that squeezes at a pressure of 5 MPa to 20 MPa, and removed. Molded by water treatment.

Thereby, a plate-like agglomerate (dust cake) having a moisture content of about 15% by mass and a thickness of 20 to 40 mm (in this example, about 30 mm) is obtained. Since this agglomerate is dense and can reduce the powdering rate, the work efficiency can be improved.

[0033] In this high pressure filter press, the medium fine dust is blocked from the atmosphere by the water coexisting in the slurry, so that the metallic iron contained in the medium fine dust is agglomerated without being oxidized. Is done. The agglomerate is then further dried as necessary (moisture content, for example, 2-5% by mass) and charged into the converter or electric furnace.

In this case as well, the agglomeration conditions such as the shape and size of the agglomerate, the type and amount of binder added, and the pressing pressure are not particularly limited as long as pulverization can be suppressed during charging into the converter or electric furnace. The above-described high-pressure filter press is limited to this as long as the above-described press pressure can be achieved, which is a conventionally known device that pressurizes while filling slurry-like medium fine dust between adjacent filters. It is not a thing.

[0034] In the examples described above, the case has been described in which medium fine dust is agglomerated and used as a converter raw material or an electric furnace raw material. However, medium fine dust with a zinc content of 1% by mass or less corresponds to 20% by mass of zinc-containing fine dust, and the proportion of this dust to the blast furnace raw material is as small as several mass%. Even if it is inserted into the blast furnace without any treatment, operational troubles such as shelves will not occur.

Therefore, a part of medium fine dust (for example, about 5 to 95 mass% of all medium fine dust separated by hydrocyclone 15) is dried without dezincing treatment as shown in Fig. 3. And after forming, it may be charged into the blast furnace as a blast furnace raw material (may be used as a sintering raw material for the blast furnace).

[0035] Next, the fourth step will be described.

As shown in FIGS. 1 and 3, the fine particle dust separated by the hydrocyclone 15 is sent to the second slurry receiving tank 18, and then the second slurry receiving tank 18 is provided with the second dust receiving tank 18. The mixture is stirred by the mechanical stirrer 19 and conveyed to the filter press 21 by the second slurry pump 20 while preventing sedimentation of fine dust.

As shown in FIG. 3, the fine-grained dust is dehydrated by a filter press 21 and dried until the water content (water content) becomes about 10% by mass, followed by molding and dezincing treatment. By this dezincing treatment, zinc is vaporized and iron oxide is reduced to metal iron (M—Fe), so that it is directly used for blast furnace recycling as a blast furnace raw material. The molding and dezincing treatment can be performed by any method disclosed in, for example, Japanese Patent Application Laid-Open No. 7-70662 or Japanese Patent Application Laid-Open No. 8-260066. Also, the fine particle dust can be made into an agglomerate by using the above-mentioned medium fine particle agglomeration treatment, and used as a converter raw material. As described above, the embodiment of the present invention has been described. However, the present invention is not limited to this embodiment, and modifications can be made without changing the gist of the invention. The case where the method for recycling zinc-containing converter dust of the present invention is configured by combining some or all of the examples is also included in the scope of the present invention.

For example, in the method for recycling zinc-containing converter dust of the above embodiment, medium fine dust is mixed with lime powder, coatas, powdered ore, etc., and charged into a sintering machine, and then charged into a blast furnace as sintered ore. May be.

In addition, after drying a part of the medium fine dust (for example, about 5 to 30% by mass of the total medium fine dust) until the water content becomes 2 to 5% by mass without dezincing, It can also be used as a converter raw material or an electric furnace raw material in the same manner as coarse dust.

The third step and the fourth step may be performed simultaneously in parallel or may be performed first.

Industrial applicability

[0037] By separating the zinc-containing converter dust generated in the converter process during the production of steel into a dust with a low zinc content and a dust with a high zinc content, In addition, it can be efficiently and efficiently recycled to a blast furnace, converter, or electric furnace without dezincing, which increases equipment costs. In addition, the dust content with a high zinc content is low because the zinc content does not need to be dezinced and the dust content is separated in advance! Processing costs can be reduced.

Claims

The scope of the claims

[1] Separation of coarse particles from converter dust recovered by wet dust collector, with a zinc content of 0.

A first step of obtaining zinc-containing fine-grained dust having a content of 5% by mass to 10% by mass and an iron content of 50% by mass to 90% by mass;

The fine-grained dust is subjected to a dezincing treatment after drying and used as a blast furnace raw material as it is, or a fourth step as an agglomerated raw material to be used as a converter raw material. Method.

[2] In the method for recycling zinc-containing converter dust according to claim 1, a part of the medium fine dust separated in the second step is dried and used as a blast furnace raw material without dezincing treatment. A method for recycling zinc-containing converter dust characterized by being used.

[3] In the method for recycling zinc-containing converter dust according to claim 1, in the press treatment in the third step, the moisture content of the medium fine dust separated by the hydrocyclone is 10% by mass or more and 15% by mass. The zinc-containing converter dust recycling method is characterized in that the agglomerate is produced by adjusting the content to less than or equal to% and kneading by adding the binder and then placing the mixture in an extrusion press and extruding under pressure.

[4] In the method for recycling zinc-containing converter dust according to claim 1, in the press treatment in the third step, the moisture content of the medium fine dust separated by the hydrocyclone is 30% by mass or more and 60% by mass. The plate-like agglomerate is produced by forming with a high-pressure filter press that is squeezed at a pressure of 5 MPa or more and 20 MPa or less after the binder is added and stirred. Recycling method for zinc converter dust.

[5] In the method for recycling zinc-containing converter dust according to claim 1, separated in the second step. A method for recycling zinc-containing converter dust, characterized in that a part of the medium fine-grained dust is not subjected to dezincing treatment, but is used as a converter raw material or an electric furnace raw material as it is after drying.