KR101777208B1

KR101777208B1 - Method for recovering precious metal

Info

Publication number: KR101777208B1
Application number: KR1020150181310A
Authority: KR
Inventors: 정용수; 김형석; 김현; 안선형
Original assignee: 재단법인 포항산업과학연구원
Priority date: 2015-12-17
Filing date: 2015-12-17
Publication date: 2017-09-12
Also published as: KR20170073020A

Abstract

Preparing a byproduct of producing a valuable metal-containing steel product, controlling a total metal content of the byproduct-containing steelmaking by-product to 50 wt% or more, mixing a reducing agent and a binder in the steelmaking by- A step of obtaining a single light by press molding, and a step of solid-phase reducing the single light.

Description

[0001] METHOD FOR RECOVERING PRECIOUS METAL [0002]

The present invention relates to a method for recovering valuable metals, and more particularly, to a method for recovering valuable metals from steelmaking by-products containing valuable metals.

At present, byproducts (for example, scale, sludge and dust) generated in the steel industry are small in size and wet, and there is no suitable recycling method suitable for the by-product form, and most of them are processed by landfill. (Rotary Hearth Furnace). There are two commercialized processes for the recovery of valuable metals contained in steel byproducts.

The first is the Waelz process, which is the process of recovering Zn from steel by-products. However, the Waelz process can be applied only when the Zn concentration of the steel by-product is relatively high. As a result, it is possible to restrict the recovery of the electric furnace dust and sludge having high Zn concentration among the by-products generated in the steel industry. And there is a disadvantage in that a large amount of carbon dioxide, which is one of the greenhouse gases, is generated.

The second is the FASTMET process, which is the process of recovering Fe from steel byproducts. However, the FASTMET process can be applied only to recovery of dust and sludge having a relatively high Fe concentration among the byproducts generated in the steel industry, and thus its application range is limited. This also causes a large amount of carbon dioxide .

One of the objects of the present invention is to provide a method for recovering valuable metals from steelmaking by-products containing valuable metals.

According to an aspect of the present invention, there is provided a method for manufacturing a steel product, comprising preparing a by-product of steelmaking containing a valuable metal, controlling a total metal content of the byproduct metal-containing steelmaking by-product to 50 wt.% Or more, A step of blending a reducing agent and a binder to obtain monochromatic light by pressure molding, and solid phase reduction of the monochromic light.

As one of the various effects of the present invention, there is an advantage that a valuable metal having a high added value can easily and economically be recovered from steelmaking by-products.

As one of the various effects of the present invention, there is no additional by-product and there is an advantage that the valuable metal can be recovered environmentally.

The various and advantageous advantages and effects of the present invention are not limited to the above description, and can be more easily understood in the course of describing a specific embodiment of the present invention.

1 is a flowchart schematically showing a method for recovering valuable metals according to the present invention.
Figure 2 is a photograph of recovered Fe-X (where X is a valuable metal) and secondary by-products, according to one embodiment of the present invention.
Fig. 3 is an Elling diagram for explaining the reduction temperatures of Fe, Ni and Cr.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for recovering valuable metals, which is an aspect of the present invention, will be described in detail with reference to the accompanying drawings.

All terms (including technical and scientific terms) used herein can be used in a sense commonly understood by one of ordinary skill in the art to which the present invention belongs, unless otherwise defined. Whenever a component is referred to as "including" an element throughout the specification, it is to be understood that the element may include other elements, not the exclusion of any other element, unless the context clearly dictates otherwise.

Steps to prepare steelmaking by-products

First, a by-product metal-containing steelmaking by-product is prepared.

In the present invention, the specific kind of the steelmaking by-products is not limited and may be, for example, a scale, sludge or dust generated in the steelmaking industry.

In the present invention, the kind of the valuable metal contained in the steelmaking by-products is not particularly limited, but may be one or more selected from the group consisting of Cr, Ni, Zn and Mn, for example.

However, in order to maximize the recovery of valuable metals, it is desirable to control the total metal content of the steelmaking by-products to 50 wt% or more. If the total metal content of the by-product metal-containing steelmaking by-products is less than 50% by weight, the steelmaking by-products containing a large amount of metal components are further mixed so that the total metal content of the steelmaking by- desirable. This is because when the total metal content is more than 50% by weight, it is advantageous to form aggregates (Nugget) by bonding metals as a homogeneous component in the reduction process, and the reducing gas is easily discharged due to easy reduction of the reducing gas.

Dankwang Steps to Obtain

Next, a reducing agent and a binder are mixed with the above-mentioned valuable metal-containing steelmaking by-products, and the mixture is pressure-molded to obtain single-phase light.

According to an embodiment of the present invention, the reducing agent may be at least one member selected from the group consisting of a carbon-based reducing agent, a silicone-based reducing agent, and an aluminum-based reducing agent, wherein the carbonaceous reducing agent is selected from the group consisting of coke, coal and graphite Based reductant may be at least one selected from the group consisting of Ferro-Si powder and Si powder, and the aluminum-based reductant may be at least one selected from the group consisting of Al-Si alloy powder and Al powder have.

According to an embodiment of the present invention, the molar amount of the reducing agent incorporated in the steelmaking by-product may be 0.5 × [O] to 1.5 × [O] or less. If the amount of the reducing agent is less than 0.5 × [O], there is a fear that the oxygen reduction rate is low to obtain a high-quality valuable metal. On the other hand, when the amount of the reducing agent is more than 1.5 × [O] And there is a fear that the reductant remaining after not participating in the reaction reacts with each other to interfere with the reduction of the metal oxide. Here, [O] means the amount (mol) of oxygen contained in the by-product-containing steelmaking by-products.

According to one embodiment of the present invention, the binder may be at least one selected from the group consisting of water glass, rosin powder and bentonite. When such a binder is used, it can be reused as slag flux when secondary byproducts are generated.

According to an embodiment of the present invention, the amount of the binder blended in the steelmaking by-products may be 0.5 wt% or more and 3 wt% or less based on the steel by-product. If the amount of the binder is less than 0.5% by weight, sludge or dust having a small particle size may not be formed into a single-shot type or may be crushed due to weak strength during operation. On the other hand, A very dense structure is formed, so that the oxygen-based gas generated by the reduction can not be emitted to the outside, and the oxygen-based gas may remain in the single-beam.

According to one embodiment of the present invention, the basicity of the steelmaking by-products in which the reducing agent and the binder are blended can be adjusted to 0.5 to 5, and more preferably 1 to 3 before the press molding. As described above, the basicity of the by-product metal-containing steelmaking by-product is controlled prior to the production of the monochromatic light so that the monochromatic light can form a low melting point so that the solid phase can be reduced with a small energy. Thus, the basicity control can be performed before the reducing agent and the binder And may be carried out after the combination of the reducing agent and the binder. If the basicity is less than 0.5 or more than 5, there is a fear of too much energy consumption when the solid phase is reduced due to excessive rise of the melting point.

According to an embodiment of the present invention, at least one selected from the group consisting of CaO and SiO ₂ may be added during the basicity control to adjust the basicity.

According to an embodiment of the present invention, the mean circular equivalent diameter of the single light may be 0.5 to 3 cm. If the average circle-equivalent diameter of the single light is less than 0.5 cm, there is a fear that the single light will be difficult to manufacture and broken during operation. If the average circle-equivalent diameter is more than 3 cm, energy required for reduction to the interior of the single light will not be transmitted That is, the internal temperature of the single light is low, so that the reduction may not be sufficiently performed.

According to an embodiment of the present invention, the moisture content of the single light may be 1 to 10. For the production of a single light, a minimum amount of moisture is required, where the moisture acts as a binder. For this purpose, the moisture content needs to be 1 or more. However, when the water vaporization temperature is 100 ° C., the water evaporates before reaching the temperature required for the solid phase reduction (about 500 ° C. or more). If the water content is too high, too much water vapor escapes before the solid phase reduction The single light may be destroyed. In order to prevent this, the water content needs to be 10 or less.

Stage of solid phase reduction

Next, the single light is solid-reduced. This step is carried out in order to precipitate a rare earth metal in the form of Fe-X (where X means a valuable metal). In this step, it is important to set the reduction temperature, Different depending on the type of metal. The major reason for distinguishing the by-products is that the steel by-products contain Fe and Ni, the steel by-products contain Fe and Cr, and the steelmaking by-products contain Fe, Ni and Cr. Because.

Fig. 3 is an Elling diagram for explaining the reduction temperatures of Fe, Ni and Cr. Referring to FIG. 3, it can be seen that in the case of Fe, the reduction temperature is in the range of 1000 to 1100 ° C., in the case of Ni, the reduction temperature is 200 to 400 ° C., and in the case of Cr, the reduction temperature is 1200 to 1400 ° C. This is because the reduction temperatures are different because the degree of oxidation of each element is different.

If the by-product metal-containing steelmaking product contains Fe and Ni or contains Fe, Ni and Cr, the first solid-phase reduction at a temperature of 200 to 1000 占 폚 (more preferably, at a temperature of 400 to 800 占 폚) And a second solid reduction step at a temperature of 1000 to 1400 ° C (more preferably, at a temperature of 1000 to 1200 ° C).

In this case, the first solid reduction is performed to reduce Ni. If the temperature is lower than 200 ° C during the first solid reduction, there is a fear that Ni is not reduced. On the other hand, if it exceeds 1000 ° C, There is a possibility that some of them are employed in non-metallic oxides. On the other hand, in the first solid phase reduction, the reduction time may be 5 to 30 minutes.

In this case, the second solid phase reduction step is carried out to precipitate Ni in the form of Fe-Ni or Fe-Cr-Ni. If the second solid phase reduction temperature is less than 1000 ° C, Fe can not be sufficiently reduced, Fe-Ni or Fe-Cr-Ni may not be obtained. On the other hand, the higher the secondary solid phase reduction temperature, the more favorable the reduction of Fe, but if the temperature is excessively high, the energy consumption is disadvantageous, and the upper limit can be limited to 1400 ° C. On the other hand, in the second solid phase reduction, the reduction time may be 5 to 30 minutes.

In the case where the by-product metal-containing steelmaking by-product contains Fe and Cr, unlike the above example, even if the solid phase reduction at a temperature of 1000 to 1400 ° C (more preferably, at a temperature of 1000 to 1200 ° C) It can be recovered effectively. In this case, the reduction time may also be 5 to 30 minutes.

Steps to recycle

Next, the reduced single light is recycled.

At this time, the recycling method may be different depending on the total metal content of the solid-reduced light.

If the total metal content of the solid phase reduced single light is 50 wt% or more, the solid phase reduced single light can be recycled as a steel raw material.

If the total metal content of the solid phase reduced single light is less than 50% by weight, it is preferable that the solid phase reduced single-phase light source is a Fe-X (where X means a valuable metal) , The valuable metal in the form of Fe-X (where X means a valuable metal) can be recycled as a steel raw material, and the secondary by-product can be recycled as a slag preparing agent.

At this time, the valuable metal and the secondary by-product can be separated by imparting vibration or by separating the magnetic force and specific gravity of the means.

Hereinafter, the present invention will be described in more detail by way of examples. It should be noted, however, that the embodiments described below are intended to illustrate the present invention and to make it more specific and not to limit the scope of the present invention. And the scope of the present invention is defined by the matters described in the claims and the matters reasonably inferred therefrom.

( Example )

Sludge and dust having the composition shown in Table 1 were prepared as the by-product metal-containing steelmaking by-products.

Composition (% by weight) [O]
(mol) FeO _X Cr ₂ O ₃ NiO CaO MgO SiO ₂ C Sludge 66.0 16.2 - 7.7 4.1 1.2 3.4 0.23 Dust 40.5 10.2 2.2 23.8 0.8 2.4 1.2 0.15

In the case of the sludge, 2.7 g of a reducing agent (pulverized coal) and 0.3 g of a binder (bentonite) were blended in 14 g of the sludge, and the mixture was press-molded to produce a single-color light source having an average circle equivalent diameter of 0.8 cm , And the solid phase reduction was performed at 1200 DEG C for 30 minutes. Thereafter, the precious metal and the secondary byproduct were separated from the solid phase reduced single light. The weight of the obtained valuable metal was about 11 g, and the weight of the secondary by-product was 5 g. These compositions are shown in Table 2 below.

On the other hand, in the case of dust, 1.7 g of a reducing agent (pulverized coal) and 0.45 g of a binder (bentonite) were blended in 14 g of dust, and the mixture was press-molded to produce a single- And then subjected to a first solid phase reduction at 800 DEG C for 15 minutes and a second solid phase reduction at 1100 DEG C for 15 minutes. Thereafter, the precious metal and the secondary byproduct were separated from the solid phase reduced single light. The weight of the separated valuable metal was about 8 g, and the weight of the secondary by-product was about 7 g. These compositions are shown together in Table 2 below.

(% By weight) Secondary by-products (% by weight) Fe Cr Ni FeO _X Cr ₂ O ₃ NiO CaO Sludge 78 20 - 30 10 - 42 Dust 73 17 6 20 7 - 60

Claims

Cr, Ni, Zn, and Mn, and controlling the total metal content of the crude metal-containing steelmaking by-products to 50 wt% or more;
Adding a reducing agent and a binder to the steelmaking byproduct whose total metal content is controlled and obtaining a single light by press molding; And
And solid-reducing the single light,
Wherein the solid phase reduction step comprises:
Subjecting the single light to a first solid phase reduction at a temperature of 200 to 1000 ° C; And
And a second solid phase reduction of the first solid phase reduced single light at a temperature of 1000 to 1400 DEG C,
Further comprising the step of separating the Fe-X type valuable metal and the secondary by-product from the solid-phase reduced mono-phase when the total metal content of the solid-phase reduced mono-phase is less than 50 wt%
Further comprising recycling the Fe-X type valuable metal as a steel raw material and recycling the secondary by-product as a slag conditioning agent,
Wherein X in Fe-X is at least one selected from the group consisting of Cr, Ni, Zn, and Mn.

The method according to claim 1,
And controlling the basicity of the steelmaking byproduct whose total metal content is controlled to be 0.5 to 5 before the press molding.

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The method according to claim 1,
Wherein the reducing agent is at least one selected from the group consisting of a carbon-based reducing agent, a silicon-based reducing agent, and an aluminum-based reducing agent.

5. The method of claim 4,
Wherein the carbon-based reducing agent is at least one selected from the group consisting of coke, coal and graphite, and the silicon-based reducing agent is at least one selected from the group consisting of Ferro-Si powder and Si powder, and the aluminum- Powder, and Al powder.

The method according to claim 1,
Wherein the molar amount of the reducing agent incorporated in the steelmaking by-product is 0.5 x [O] to 1.5 x [O].
(Wherein, [O] means the amount (mol) of oxygen contained in the by-product metal-containing steelmaking by-product)

The method according to claim 1,
Wherein the binder is at least one selected from the group consisting of water glass, rosin powder and bentonite.

The method according to claim 1,
Wherein the amount of the binder to be blended in the steelmaking by-product is 0.5 wt% to 3 wt% of the steelmaking by-product.

3. The method of claim 2,
Wherein the basicity is controlled by introducing at least one selected from the group consisting of CaO and SiO ₂ during the basicity control.

The method according to claim 1,
Wherein the average circle equivalent diameter of the single light is 0.5 to 3 cm.

The method according to claim 1,
Wherein the moisture content of the single light is 1 to 10%.

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The method according to claim 1,
And the reduction time is 5 to 30 minutes in the first solid phase reduction.

The method according to claim 1,
And the reduction time is 5 to 30 minutes in the second solid phase reduction.

The method according to claim 1,
Further comprising the step of recycling the solid phase reduced single light as a steel raw material when the total metal content of the solid phase reduced single light is 50 wt% or more.

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