JPH08325617A - Method for separating and recovering zinc from zinc-containing material - Google Patents

Abstract

PURPOSE: To recover Zn from Zn-contg. material by inserting the Zn-contg. material into a converter and supplying generated dust to a molten iron pretreatment. CONSTITUTION: The Zn-contg. material 1 is charged into the converter 2 and the converter dust 3 generated by blowing is prepd. as a dephosphorizing agent 4 which is introduced to the molten iron pretreatment 5. The pretreatment dust 6 generated during the pretreatment is recovered and the Zn is concentrated and separated. Further, the recovered pretreatment dust is supplied again to the pretreatment and is concd. at a high concn. The concn. of the Zn to be recovered and is controlled to a prescribed value by setting the adding amt. of the pretreatment dust to be supplied to the dephosphorizing agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating a substance containing Zn in a steel mill, and more specifically, a dust generated by using the substance containing Zn in a converter is further used in hot metal pretreatment. The present invention relates to a method for efficiently separating and recovering Zn from a Zn-containing substance by taking such means.

[0002]

2. Description of the Related Art Conventionally, there have been many studies on a technique of using a Zn-containing substance in an iron mill, and as a method for treating a Zn-containing substance, a mechanical separation method, a thermal separation method, and a chemical separation method have been proposed. is there. In particular, as a proposal regarding a separation method by heat, JP-A-5-195094 and JP-A-63-62813 describe that a scrap containing Zn is charged into a converter for introducing hot metal, and Z generated especially in the initial stage of blowing.
A method of collecting n-dust through a duct is disclosed.

Further, in Japanese Patent Laid-Open No. 53-46406, the dust containing zinc oxide is blown into the hot metal contained in a closed hot metal ladle, so that the zinc oxide in the dust is thermally reduced and evaporated. , A method of recovering Zn by recovering evaporated Zn vapor with a filter through a duct is disclosed.

[0004]

However, in the above-mentioned prior art, it is necessary to add a new step for applying heat to the Zn-containing substance, or to add a heat source to compensate for the heat. Capital investment is required. Further, since energy has to be newly input to add a heat source, there is a problem that running cost on the way also increases.

Further, it is necessary to install a hood or the like for hermetically sealing or creating a reducing atmosphere, and at the same time, due to rocking of the hot metal or slag together with a low boiling point metal such as Zn, or generation of a locally high temperature portion. Since the high-boiling-point metal mainly composed of iron is also evaporated, there is a problem that the recovered Zn dust does not have a high concentration.

[0006] Therefore, the object of the present invention is to efficiently separate and collect Zn of a high concentration or a predetermined concentration for resource recycling without requiring a large capital investment and running cost for adding a heat source. It is to provide a method for separating and recovering Zn from a contained substance.

[0007]

In order to achieve the above object, the present invention as set forth in claim 1 is to introduce a Zn-containing substance into a converter as a first stage and to contain a Zn oxide as a second stage. Adjusting converter dust as de-P agent, Z as the third stage
The Zn content is separated by supplying the deoxidizing agent containing the n oxide to the hot metal pretreatment and collecting the Zn oxide as the pretreatment dust during the pretreatment as the fourth step.

Further, the present invention as set forth in claim 2 is a method for separating Zn from a Zn-containing substance according to claim 1, wherein
It is characterized in that the concentration of the recovered Zn component is increased by supplying the pretreatment dust obtained in the fourth stage again to the hot metal pretreatment as a de-P agent.

Further, the present invention as set forth in claim 3 is the method for separating and recovering Zn from a Zn-containing substance according to claim 2, wherein the hot metal preliminary of the pretreatment dust is set so that the recovered Zn concentration becomes a predetermined value. It is characterized by setting the reuse rate for processing.

Further, the present invention as set forth in claim 4 is characterized in that, in the method for separating and recovering Zn from a Zn-containing substance according to any one of claims 1 to 3, the Zn-containing substance is supplied into a converter together with steel scrap. I am trying.

[0011]

According to the present invention as set forth in claim 1, in the first step, the Zn-containing substance is recovered as converter dust containing Zn oxide by converter blowing, and after being adjusted as a de-P agent in the second step. In the third stage, it is supplied to the hot metal pretreatment as a de-P agent, and in the fourth stage Z
Since n oxide is recovered as pretreatment dust during pretreatment, it is necessary as a Zn material by further supplying converter dust containing Zn oxide by converter blowing to the hot metal pretreatment and recovering it as pretreatment dust. It is possible to obtain Zn-containing dust with various concentrations.

According to the second aspect of the present invention, the pretreatment dust obtained in the fourth step of the method according to the first aspect is further supplied to the hot metal pretreatment to increase the concentration of the recovered Zn content. Further, it is possible to obtain a Zn-containing dust having a higher concentration.

Further, according to the present invention as set forth in claim 3,
Since the recycling rate of the pretreatment dust is set so that the Zn concentration recovered by the method according to claim 2 is set to a predetermined value,
It is possible to control the Zn concentration of the recovered dust to a predetermined value.

According to the present invention as set forth in claim 4, in the method as set forth in claims 1 to 3, the Zn-containing substance is supplied into the converter together with the steel material scrap. Even if a substance other than the above is mixed, it can be processed without any problem.

[0015]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a process for separating and recovering Zn from a Zn-containing substance according to an embodiment of the present invention.

In FIG. 1, first, a Zn-containing substance 1 (in this case, a process for charging a Zn-containing substance, to be precise, the process is omitted and only the proper name is used) is charged into a converter 2. 160 in contact with hot metal in furnace 2 by blowing
The temperature is raised to 0 ° C or higher.

Since the boiling point of metallic Zn is 906 ° C., when the contained Zn content exists as metallic Zn, it is positively evaporated. On the other hand, when it exists as Zn oxide, as shown in the following equation (1), Zn0 (solid) + C (liquid) → Zn (vapar) + CO (gas) ... (1) Since ZnO is reduced and decomposed into metallic Zn by the reaction with [C] in the hot metal, similarly, the hot metal in the converter 2 is sufficiently evaporated while the temperature is raised from 1200 ° C to 1600 ° C. In a normal converter operation, dust containing iron as a main component is produced in an amount of about 10 to 20 kg per 1 t of molten steel, so that the Zn concentration in the converter dust 3 is not so high and the maximum is about 20%.

Further, since the duct for recovering the converter dust 3 is not generally sealed, Zn vapor or the like is easily brought into contact with air, and the recovered dust 3 is almost oxidized. In particular, in a steel mill, a wet dust collector is often introduced to collect dust from the converter 2, and high-boiling metals such as iron and low-boiling metals such as Zn generated by contact with water are (2 Since Zn is easily oxidized by the reaction represented by the formula), the recovered Zn is in the form of ZnO.

Zn (vapar) + 1 / 2.O ₂ (gass) → ZnO (solid) ... (2) Here, since the zinc content contained in the converter dust 3 does not reach a high concentration, the converter dust 3 is reused. In order to supply Zn into the converter 2 and to concentrate it, although it is true that Zn selectively concentrates into dust generated from the converter 2, if powdery dust is directly supplied to the converter 2, Agglomeration treatment is required because the amount of scattering to the outside of the furnace increases, and in addition, since iron content is generated from the converter 2, the Zn content is unlikely to have a high concentration and the efficiency is poor.

Therefore, in this embodiment, a method is adopted in which the converter dust 3 is returned to the hot metal pretreatment and concentrated again. The conventional hot metal pretreatment process itself is a process of selectively removing P in the hot metal by supplying iron oxide together with lime into the hot metal. The dust generated from the ironmaking process was dried and used in powder form. However, this time instead of Zn
The converter dust 3 containing is used. Dust centered on iron is generated during the hot metal pretreatment, but 1 t of hot metal
The amount of Zn generated per treatment is about 3 to 5 kg, which is smaller than that in the converter 2, and the ratio of Zn to iron in the dust (Zn
(Corresponding to the concentration) can be increased. By collecting this dust and reducing ZnO, the metal Zn content 8 can be effectively recovered.

Therefore, first, the converter dust 3 containing up to 20% of Zn, which is recovered from the converter 2, is dried to produce the dephosphorization agent 4 containing powdered ZnO. It should be noted that the oxygen content in iron oxide reacts with the dephosphorization (phosphorus), so that the oxygen content existing as ZnO also reacts. According to the method of the present embodiment, the Zn content is particularly removed. Since no special treatment is required and the treatment range originally required for hot metal reserves is sufficient, no additional treatment cost due to capital investment, running cost, etc. as in the past is incurred.

The behavior of ZnO blown into the hot metal 7 as the P removal agent 4 in the hot metal pretreatment 5 is that the oxygen content reacts with phosphorus P and contributes to the removal of P, and the Zn content becomes a metal Zn atom.
It easily evaporates at a hot metal temperature of 00 to 1400 ° C.
In the hot metal dephosphorization treatment, it is desirable that the Si concentration in the hot metal be low, preferably 0.1% or less. However, due to the variation in the hot metal desilvering process, the dePing process by blowing ZnO is possible within the range of up to about 0.5%. In addition, the reaction efficiency of oxygen to P removal when ZnO is used is almost the same as that when iron oxide is used.

The Zn concentration of the converter dust 3 generated from the converter 2 depends on the Zn content in the scrap, but due to the iron content generated from the converter 2, the Zn concentration is only up to about 20%. Therefore, in order to obtain a Zn-containing dust having a higher concentration, the hot metal pretreatment dust 6 containing Zn once concentrated to a high concentration in the hot metal pretreatment 5 is blown again as a hot metal pretreatment agent to obtain a higher concentration. It is possible to concentrate to a concentration, up to 70%.

Originally, the optimum Zn concentration required by a zinc refining maker may change depending on the production and demand conditions of Zn ingot, so it is necessary to adjust the Zn concentration according to the demand from the viewpoint of resource recycling. Is. The adjustment of the Zn concentration can also be easily controlled by setting the blowing amount ratio of the pretreatment dust to the hot metal pretreatment 5 in this embodiment.

[0025] Further, in steel mills, the consumption of Zn scrap generated in the plant is mainly executed, but recently, Zn scrap is consumed.
Since the amount of plated steel scraps generated from the market is increasing, a method for more positively consuming scraps from the market is desired. Not only steel scrap but also general waste containing Zn, especially dust containing Zn, sludge, etc., can be recovered into the converter 2 without any special preliminary treatment by first charging the same into scrap. It became possible.

The above-mentioned Zn-containing substance 1 is intended for steel scrap, sludge, dust, ore, etc., and contains Zn as a component. In many cases, the scraps to be sorted are not satisfactorily sorted, and materials such as stainless steel containing Cr, scraps such as wire rods containing Pb, and scraps containing copper wires are often mixed. Also in this case, it is possible to perform processing without problems by the method of this embodiment.

Next, an operation example performed under actual conditions will be described.

First, in the first example, the dust 3 generated from the converter 2 was investigated under the condition that the scrap 1 containing 4% of Zn was charged into the converter 2 having a capacity of 250 T / heat. FIG. 2 is a diagram showing the amount of converter dust generated from the converter and the Zn concentration, and shows the total dust generation rate and the Zn content generation rate as the investigation results.

In FIG. 2, the lower Zn content generation rate curve is 10 to 5 compared to the upper total dust generation rate curve.
It is 0%, and this value represents the Zn concentration in the dust 3. The generated amount can be calculated by integrating the area surrounded by the broken line in FIG. 2. The result is that the total generated amount of the converter dust 3 is 19 Kg / t and the average Zn concentration in the dust is 1
It was 8%. Only 5 ppm of residual Zn was present in the molten steel at the time of blowing stop after the medium carbonaceous material was melted by this 18-minute smelting, and most of the injected Zn was converted into converter dust 3
It was confirmed that it had evaporated inside.

Next, as a second example, in the hot metal pretreatment method of injecting the de-P agent into the hot metal in the TPC at 270 t / heat, the converter dust 3 with a Zn concentration of 20% generated from the converter 2 is removed. The P agent 4 was blown from the top with a blowing lance to collect the pretreatment dust 6 generated during the treatment.

FIG. 3 is a diagram showing the amount of pretreatment dust and the Zn concentration using the converter dust as the de-P agent, and shows the total dust generation rate and the Zn content generation rate of the actual pretreatment dust 6. The collection state is shown. As shown in FIG. 3, the lower Zn generation rate curve is 40 to 60% compared with the upper total dust generation rate curve, and this value represents the Zn concentration in the dust 6. Also in this case, the total dust generation amount can be calculated by integrating the inside of the polygonal line in the figure, and the result was that the total dust generation amount of the pretreatment dust 6 was 5 Kg / t and the average Zn concentration in the dust was 55%. In addition, the amount of Zn residue in the hot metal was 600 ppm
The n minutes are selectively concentrated in the pretreatment dust 6. T
In the pretreatment of PC, since the Zn content is blown in, the Zn content in the pretreatment dust 6 is high, but the residual Zn content in the hot metal becomes large, but it is sufficiently removed from the molten steel by the subsequent converter blowing. it can.

Next, as a third example, the pretreatment dust 6 containing a high concentration of Zn generated from the hot metal pretreatment 5 is removed by P removal.
The pretreatment dust 6 generated during the treatment was recovered under the condition that the agent 4 was mixed with the compounding agent at a different mixing ratio and was blown into the hot metal 7 to carry out the pretreatment, and the generated amount and the Zn concentration were analyzed.

FIG. 4 is a graph showing the relationship between the compounding ratio of the high Zn concentration dust to the P-eliminating agent and the Zn concentration of the generated dust.
As the mixing ratio of the high Zn dust of the P-eliminating agent 4 becomes higher, the Zn concentration in the pretreatment dust 6 generated also increases,
The maximum Zn concentration has improved to 70%, and the injected Zn
The fraction is selectively concentrated in the dust. From these, it is possible to adjust the Zn concentration of the hot metal pretreatment agent to be blown by adjusting the blending ratio of the high Zn concentration dust and the low Zn concentration dust to adjust the Zn concentration in the generated pretreatment dust 6. Became.

[0034]

As described above, according to the present invention,
In the first step, the converter dust was recovered by converter blowing using the Zn-containing substance, in the second step it was adjusted as a de-P agent, and in the third step, the de-P agent was supplied to the hot metal pretreatment, Z in stages
The n oxide is recovered as pretreatment dust. The pretreatment dust collected in the fourth stage is further supplied to the hot metal pretreatment for reuse in order to increase the concentration of Zn, and the reuse ratio of the pretreatment dust is controlled in order to control the Zn concentration of dust to a predetermined value. Since the Zn content is set, Zn content of 50% to 70% from Zn-containing material such as scrap having a Zn concentration of 4% or less is set.
It becomes possible to collect the pretreatment dust containing n,
In addition, the treatment and equipment for recovery do not require any special additions other than the work of the conventional hot metal pretreatment, and no surplus cost is required. The Zn content can be separated by a simple and inexpensive method, and there is an effect that the amount of industrial waste that has been disposed of in large quantities due to the low concentration is drastically reduced.

[Brief description of drawings]

FIG. 1 shows Z from a Zn-containing material according to an embodiment of the present invention.
It is a figure which shows the separation collection process of n.

FIG. 2 is a diagram showing the amount of converter dust and the Zn concentration generated from the converter shown in FIG.

FIG. 3 is a diagram showing an amount of pretreatment dust and a Zn concentration in which the converter dust shown in FIG.

FIG. 4 is a diagram showing the relationship between the compounding ratio of high Zn concentration dust to the P-eliminating agent shown in FIG. 1 and the Zn concentration of generated dust.

[Explanation of symbols]

 1 Zn-containing substance 2 Converter 3 Converter dust 4 De-P agent 5 Pretreatment of hot metal 6 Pretreatment dust 7 Hot metal 8 Zn recovery

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seiji Yamamoto 1 Kimitsu, Kimitsu-shi Kimitsu Corporation Nippon Steel Corporation (72) Inventor Tetsuji Ibaraki Kimitsu, Kimitsu City 1 Nippon Steel Corporation Kimitsu Inside the steelworks

Claims (4)

[Claims] 1. A Zn-containing substance is charged into a converter as a first stage, and a Zn content is recovered as converter dust containing Zn oxide during blowing, and a converter dust containing Zn oxide is contained as a second stage. As a de-P agent, the de-P agent containing Zn oxide is supplied to the hot metal pretreatment as the third step, and the Zn is added as the fourth step.
A method for separating and recovering Zn from a Zn-containing substance, characterized in that a Zn content is separated by going through a step of recovering an oxide as a pretreatment dust during a pretreatment. 2. Zn from the Zn-containing material according to claim 1.
In the method for separating and recovering Zn, the concentration of Zn content recovered is increased by supplying the pretreatment dust obtained in the fourth step again to the hot metal pretreatment as a P-eliminating agent. Separation and collection method. 3. Zn from the Zn-containing material according to claim 2.
In the method for separating and recovering Zn, the reuse ratio of the pretreatment dust to the hot metal pretreatment is set so that the recovered Zn concentration becomes a predetermined value.
Separation and collection method of. 4. The method for separating and recovering Zn from a Zn-containing substance according to claim 1, wherein the Zn-containing substance is supplied into a converter together with a steel material scrap.
A method for separating and recovering Zn from an n-containing substance.