KR20240041443A - System for recovering rare earth elements of permanent magnet and method therefor - Google Patents

Abstract

The present invention relates to a system and method for recovering valuable metals from waste permanent magnets.
Among these, the valuable metal recovery method includes an acid recovery step of dissolving waste permanent magnet powder in pickling waste liquid, producing raw material powder containing valuable metals from the pickling waste liquid in which waste permanent magnet powder is dissolved, and dry density classifying the raw material powder. It may include a valuable metal recovery step of recovering valuable metal from the raw material powder.

Description

System and method for recovering valuable metals from waste permanent magnets {SYSTEM FOR RECOVERING RARE EARTH ELEMENTS OF PERMANENT MAGNET AND METHOD THEREFOR}

The present invention relates to a system and method for recovering valuable metals from waste permanent magnets.

Recently, the demand for electric vehicles is growing rapidly, and the demand for magnets containing rare earth elements, which are essential for electric vehicles, is also increasing.

Magnets containing rare earths are entirely dependent on imports, and recycling is limited to using large amounts of acid for pre-processing/recycling facilities. In order to reduce the use of large amounts of acid, it is necessary to develop technology applicable to existing plants by utilizing steel industry processes and facilities.

Meanwhile, when recycling conventional waste permanent magnets, all of the waste permanent magnets are leached in strong acid, and there is a high possibility that rare earth-containing raw materials may be mixed during the pretreatment process of some of the pickling waste liquid, so high purity is required to remove impurities that may occur in the future commercialization process. Technology is needed. This can lead to problems such as rising process costs and weakening price competitiveness.

Embodiments of the present invention are intended to provide a system and method for recovering valuable metals from waste permanent magnets that can effectively recover valuable metals contained in waste permanent magnets using a pickling process and density classification.

According to one aspect of the present invention, an acid recovery step of dissolving waste permanent magnet powder in pickling waste liquid and producing raw material powder containing valuable metals from the pickling waste liquid in which the waste permanent magnet powder is dissolved; And a valuable metal recovery step of recovering the valuable metal from the raw material powder by dry density classifying the raw material powder, a method for recovering valuable metal from a spent permanent magnet can be provided.

Additionally, the acid recovery step includes reacting the oxide layer of steel with hydrochloric acid to produce pickling waste liquid; Dissolving the waste permanent magnet powder in the pickling waste liquid; A method for recovering valuable metals from a spent permanent magnet may be provided, including producing raw material powder containing oxides and regenerated hydrochloric acid from the pickling waste liquid in which the spent permanent magnet powder is dissolved.

In addition, the oxide includes iron oxide (Fe ₂ O ₃ ) and neodymium oxide (Nd ₂ O ₃ ), and a method for recovering valuable metals from a spent permanent magnet may be provided.

In addition, the step of producing the pickling waste liquid includes providing a pickling waste liquid capable of additional dissolution of free acid up to a limit concentration so that additional dissolution of the waste permanent magnet powder is possible in the pickling waste liquid, and pickling the waste permanent magnet powder. In the step of dissolving in the waste liquid, the waste permanent magnet powder is dissolved in the pickling waste liquid using the free acid to the limit concentration, and the limit concentration is a concentration lower than the concentration of iron contained in the oxide layer that can be maximally dissolved in hydrochloric acid. , a method for recovering valuable metals from waste permanent magnets can be provided.

In addition, in the step of producing the pickling waste liquid, when the limit concentration is 160 g/L, the iron concentration of the pickling waste liquid is maintained at 120 g/L to enable additional dissolution of 40 g/L of the free acid, and the waste permanent The step of dissolving the magnet powder in the pickling waste liquid may include dissolving the waste permanent magnet powder in the pickling waste liquid in which 40 g/L of free acid is dissolved, thereby providing a method for recovering valuable metals from a waste permanent magnet.

In addition, the valuable metal recovery step includes supplying raw material powder to the main reactor; Supplying gas to the main reactor to allow raw material powder to flow in the main reactor; supplying raw material powder suspended at the upper end of the main reactor to a cyclone unit; And a method for recovering valuable metal from a spent permanent magnet may be provided, including the step of recovering valuable metal from the raw material powder in the cyclone unit.

According to one aspect of the present invention, a raw material supplier for supplying raw material powder; a main reactor providing a long chamber extending in the vertical direction so that the raw material powder can flow in the vertical direction; a gas supplier that supplies gas to the intestinal chamber so that the raw material powder flows in the main reactor; and a cyclone unit connected to the upper end of the main reactor, receiving raw material powder suspended at the upper end of the main reactor and recovering valuable metal from the raw material powder. A valuable metal recovery system for a spent permanent magnet may be provided. there is.

In addition, the main reactor includes a reaction body in which the raw material supplier is connected to an upper end, the gas supplier is connected to a lower end, and the intestinal chamber is provided therein; A valuable metal recovery system for waste permanent magnets may be provided, including a dispersion plate disposed at a lower portion of the intestinal chamber and providing a plurality of dispersion holes for the gas to pass through.

In addition, the cyclone unit may include a first cyclone and a second cyclone continuously connected to the upper end of the main reactor, and a valuable metal recovery system for waste permanent magnets may be provided.

In addition, the first cyclone includes a first cyclone unit that primarily selects raw material powder containing more valuable metals than a preset amount using centrifugal force; a first recovery unit connected to the bottom of the first cyclone unit to collect the initially selected raw material powder; A first inlet pipe section connecting the upper end of the main reactor and the first cyclone section; and a first discharge pipe unit that guides the raw material powder rotating upward in the first cyclone unit to the outside of the first cyclone unit, wherein the second cyclone uses centrifugal force to supply raw material containing more valuable metals than a preset amount. A second cyclone unit for secondary selection of powder; a second recovery unit connected to the bottom of the second cyclone unit to collect the secondary selected raw material powder; a second inlet pipe connecting the first discharge pipe and the second cyclone; And a second discharge pipe unit that guides the raw material powder rotating upward in the second cyclone unit to the outside of the second cyclone unit, a valuable metal recovery system for a spent permanent magnet can be provided.

Additionally, the reaction body includes a first-stage body portion; and a second-stage body part obliquely connected to the upper part of the first-stage body part so as to have a diameter larger than the diameter of the first-stage body part, wherein the diameter of the second-stage body part is at least twice larger than the diameter of the first-stage body part. , a system for recovering valuable metals from waste permanent magnets can be provided.

Additionally, according to embodiments of the present invention, by using an existing steel process, there is an effect of minimizing the economic burden required to develop new process technology.

In addition, according to embodiments of the present invention, hydrochloric acid can be recovered and reused by using an acid recovery process system for recycling a large amount of acid in the steel process, and iron oxide and neodymium oxide are recovered as by-products, thereby providing economic benefits. This has the effect of greatly alleviating environmental burden.

In addition, according to embodiments of the present invention, by selectively separating neodymium oxide from the mixed powder of iron oxide and neodymium oxide, which is a by-product, through a dry process, the cost of the post-process can be significantly reduced.

In addition, according to embodiments of the present invention, there is an advantage that heat energy, etc. is not required and the device configuration is relatively simple, so it can be very economical.

In addition, according to embodiments of the present invention, it is a technology that can be applied to most valuable metals including rare earth elements that can be leached in hydrochloric acid, which is a pickling waste liquid, and is an expansion of eco-friendly multi-platform technology for various materials such as magnesium (Mg) and calcium (Ca). It has excellent performance and flexibility, which can improve the economic feasibility of the rare earth recycling process in resource-poor countries and can be spread to various industries in the future.

Figure 1 is a block diagram showing a method for recovering valuable metals from waste permanent magnets according to an embodiment of the present invention.
Figure 2 is a block diagram showing a valuable metal recovery step in the valuable metal recovery method of a waste permanent magnet according to an embodiment of the present invention.
Figure 3 is a configuration diagram showing a system for recovering valuable metals from waste permanent magnets according to an embodiment of the present invention.
Figure 4 is a plan view showing a distribution plate of a valuable metal recovery system for waste permanent magnets according to an embodiment of the present invention.
Figure 5 is a configuration diagram showing a valuable metal recovery system for waste permanent magnets according to another embodiment of the present invention.

Hereinafter, the configuration and operation according to an embodiment of the present invention will be described in detail with reference to the attached drawings. The following description is one of several aspects of the invention that can be claimed for patent, and the following description may form part of a detailed description of the invention.

However, when describing the present invention, detailed descriptions of well-known structures or functions may be omitted for clarity of the present invention.

Since the present invention can make various changes and include various embodiments, specific embodiments will be illustrated in the drawings and described in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention.

Terms containing ordinal numbers, such as first, second, etc., may be used to describe various components, but the components are not limited by these terms. These terms are used only to distinguish one component from another.

The terms used in this application are only used to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

Hereinafter, a method for metalizing waste permanent magnets according to an embodiment of the present invention will be described with reference to the attached drawings.

Referring to Figures 1 and 2, the valuable metal recovery method 10 according to an embodiment of the present invention may include an acid recovery step (S100) and a valuable metal recovery step (S200).

In the acid recovery step (S100), the pickling waste liquid used in the steel pickling process can be provided. Here, the steel pickling process is a process to remove contaminants other than oxides or metal salts on the surface of metal (steel), and the oxide layer and hydroxide on the metal surface are washed with acid. The oxide layer on the metal surface may be iron oxide such as Fe ₂ O ₃ /Fe ₃ O ₄ , and as the temperature rises, a stable Fe ₂ O ₃ phase may be formed.

This oxide layer can be removed by pickling through the steel pickling process, and is generated as pickling waste liquid by the pickling reaction on the oxide layer. The pickling waste liquid generated in the steel pickling process can be used in the acid recovery step (S100).

In the acid recovery step (S100), the ARP (Acid Regeneration Plant) process, a technology for recovering and reusing hydrochloric acid, can be applied. And the acid recovery step (S100) will include a step of producing a pickling waste liquid (S110), a step of dissolving the waste permanent magnet powder in the pickling waste liquid (S120), and a step of producing raw material powder and regenerated hydrochloric acid (S130). You can.

In the step of producing the pickling waste liquid (S110), Fe ₂ O ₃ , which is an oxidation layer on the surface, can be subjected to an acid pickling reaction with hydrochloric acid (HCl). The pickling reaction of Fe ₂ O ₃ can be derived by Scheme 1 below.

[Scheme 1]

Scheme 1 is a spontaneous reaction, and the Fe concentration of the pickling solution, which is the maximum soluble concentration (limit concentration) in hydrochloric acid, may be 160 g/L. For stable operation of the RNAP process, the Fe concentration is maintained at 120 g/L, and if it is higher than that, the RNAP process for waste liquid treatment is performed. At this time, additional dissolution of solutes including Fe is possible due to the presence of 40 g/L of free acid.

Here, free acid can be understood as an acid (concentration of up to 40 g/L) that can further dissolve iron in the pickling waste liquid dissolved in hydrochloric acid. The maximum concentration at which Fe-containing solutes can be dissolved in general hydrochloric acid is 160 g/L, but when the concentration of Fe in general pickling liquid is 120 g/L to stabilize the process, the pickling liquid is used in the ARP process. It goes through this process, and at this time, 40 g/L of free acid exists. This means that an additional 40 g/L of solutes that can dissolve in hydrochloric acid, including Fe, can be dissolved, resulting in a concentration of up to 160 g/L.

In the step of dissolving the waste permanent magnet powder in the pickling waste liquid (S120), the waste permanent magnet powder (powder) can be dissolved in the pickling waste liquid using 40 g/L of free acid before the ARP process.

In the step of producing raw material powder and recycled hydrochloric acid (S130), rare earth elements can be recovered along with iron oxide through the ARP process. In the step of producing raw material powder and recycled hydrochloric acid (S130), the waste acid of FeClx (aqueos) + H ₂ O (liquid) + HCl (aqueous) is high temperature through a spray roaster at a temperature of 400 to 800 ° C. The hydrochloric acid vaporized can be recovered by re-cooling. And when FeClx meets excess oxygen, iron oxide can be produced in Reaction Formula 2 below.

[Scheme 2]

In this embodiment, the waste permanent magnet used may be a neodymium-based waste permanent magnet (NdFeB). In a neodymium permanent magnet, neodymium (Nd) may be 29 to 32 wt.%, iron (Fe) may be 64.2 to 68.5 wt.%, and boron (B) may be 1.0 to 1.2 wt.%. For example, when the waste permanent magnet powder of this example is dissolved in 40 g/L of free acid, neodymium (Nd) is 11.6 to 12.8 g/L, iron (Fe) is 25.6 to 27.4 g/L, and boron (B) is 11.6 to 12.8 g/L. may be 0.4 g/L. When waste permanent magnet powder of this composition is mixed with pickling waste liquid containing 120 g/L of iron (Fe), neodymium (Nd) is about 12 g/L and iron (Fe) is about 147 g, based on a total of 160 g/L. /L, boron (B) may be about 0.4 g/L. Converting this into fractions, neodymium (Nd) can have a ratio of up to 7.5%, iron (Fe) can have a ratio of 92%, and boron (B) and other compositions can have a ratio of 0.5%. In this way, when waste permanent magnets are dissolved in pickling waste liquid and subjected to the ㅇRP process, raw material powder containing iron (Fe) and neodymium (Nd) as respective oxides in a ratio of about 95:5 wt.% is manufactured. It can be.

The valuable metal recovery step (S200) may recover the valuable metals contained in the raw material powder by dry density classifying the raw material powder prepared in the acid recovery step (S100). This valuable metal recovery step (S200) includes supplying raw material powder to the main reactor (S100), supplying gas to the main reactor (S200), and supplying raw material powder to the cyclone unit (S300). , It may include a step (S400) of recovering valuable metals.

In the step of supplying the raw material powder to the main reactor (S100), the raw material powder contained in the raw material supplier may be supplied to the main reactor. The raw material powder supplied to the main reactor may be waste permanent magnet powder containing iron oxide (Fe ₂ O ₃ ) and neodymium oxide (Nd ₂ O ₃ ). The main reactor may be installed with a dispersion plate with a 1 mm dispersion hole or a dispersion plate with a 2 mm dispersion hole.

In the step of supplying gas to the main reactor (S200), while the raw material powder is supplied to the main reactor, the gas from the gas supplier may be supplied to the main reactor. By supplying gas into the main reactor, the raw material powder within the main reactor can be fluidized while forming a fluidized bed. The supply flow rate of gas supplied from the gas supplier may range from 1 to 100 LPM (Liter/Min).

In the step of supplying the raw material powder to the cyclone unit (S300), when the raw material powder forms a stable fluidized layer in the main reactor through gas supply in the main reactor, the raw material powder floating at the upper part of the main reactor, that is, the valuable metal (For example, raw material powder containing more iron oxide (Fe ₂ O ₃ ) and neodymium oxide (Nd ₂ O ₃ )) than a preset amount may be supplied to the cyclone unit.

In the step of recovering valuable metals (S400), raw powder containing more valuable metals than a preset amount may be recovered. Raw material powder containing more valuable metals than a preset amount can be understood as raw material powder containing a larger amount of valuable metals than the raw material powder supplied from the raw material supplier.

In the step of recovering valuable metals (S400), the raw material powder containing more valuable metals than a preset amount can be first recovered through the first cyclone connected to the upper end of the main reactor, and continuously with the first cyclone. Through the connected second cyclone, raw material powder containing more valuable metals than a preset amount can be recovered secondarily.

Meanwhile, referring to FIGS. 3 and 4, the valuable metal recovery system 20 according to an embodiment of the present invention selectively removes the valuable metals contained in the raw material powder through density classification, thereby removing the valuable metals. The efficiency of the recycling process for raw material powder can be improved. This valuable metal recovery system 20 may include a raw material supplier 100, a main reactor 200, a gas supplier 300, and a cyclone unit 400.

The raw material supplier 100 can accommodate raw material powder to be supplied to the main reactor 200. In this embodiment, the raw material powder may be a powder of neodymium-based waste permanent magnet (NdFeB) containing valuable metals (neodymium-based, etc.).

The raw material supplier 100 may include a raw material hopper 110 that can accommodate raw material powder, and a raw material valve 120 that selectively provides the raw material powder contained in the raw material hopper 110 to the main reactor 200. The raw material valve 120 opens and closes the movement path through which the raw material powder moves from the raw material hopper 110 to the main reactor 200, thereby selectively supplying the raw material powder contained in the raw material hopper 110 to the main reactor 200. .

The main reactor 200 may provide a space where raw material powder can move in the vertical direction by the flow of gas. The main reactor 200 may include a reaction body 210 and a dispersion plate 220. The reaction body 210 may provide a long chamber 211 extending in the vertical direction so as to be able to flow in the vertical direction.

A fluororesin coating (PTFE) may be formed on the inner wall of the main reactor 200. By forming a fluororesin coating (PTFE) on the inner surface of the main reactor 200, when the valuable metal in the raw material powder has a high electrostatic force and is fused to the inner surface of the main reactor 200, the discharge of the valuable metal can be easily achieved. and the recovery rate of valuable metals can be improved.

The length of the reaction body 210 can be designed to selectively suspend valuable metals in consideration of the raw material/density of the raw material powder. The length of the reaction body 210 may correspond to the flow distance of the raw material powder. In this embodiment, the length of the reaction body 210 may be 1500 mm. A raw material supplier 100 may be connected to the upper part of the reaction body 210. A gas supplier 300 may be connected to the lower part.

Meanwhile, for the separation of valuable metals, the flow rate can be selected by calculating the minimum fluidization speed using the formula (Equation 1) of Wen & Yu (1966) below. Since Wen&Yu's formula (Equation 1) is a conventional formula, detailed explanation thereof will be omitted.

[Equation 1]

Here, dp is the particle size of the material, ρ _g is the viscosity of the gas, ρ _p is the density of the particles, g is the gravity, and μ _g is the viscosity of the gas.

However, it is a solid fluid particle property representing known fluid particle sizes and particle densities and is related to the Archimedes number, which is a function of gas properties (gas viscosity and gas density). The reason for using a flow rate higher than the minimum fluidization rate is because the dispersion plate was not considered in this minimum fluidization equation, and the flow rate attenuated by the dispersion plate was taken into consideration and a flow rate higher than the minimum fluidization rate was performed.

The dispersion plate 220 may be placed at the bottom of the intestinal chamber 211. The dispersion plate 220 can deliver the gas supplied from the gas supplier 300 to the upper side of the intestinal chamber 211 so that the valuable metal in the raw material powder flows to the upper part of the reaction body 210. The dispersion plate 220 may be formed with a clamping hole 221 for fixing the reaction body 210 and a plurality of dispersion holes 222 through which gas passes. The plurality of dispersion holes 222 may be through holes formed in the center of the dispersion plate 220 and having a diameter ranging from 1 mm to 2 mm.

If the shape of the dispersion hole 222 is made in the form of a simple perforation and the diameter of the dispersion hole 222 is greater than 2 mm, which is larger than the diameter of the powder, the powder will be below the dispersion plate 220 due to the diameter of the dispersion hole 222. can fall. If the diameter of the dispersion hole 222 is less than 1 mm, air injection is not smooth, so when air is introduced into the main reactor 200, there is a gap between the air inlet part of the main reactor 200 into which the air is injected and the dispersion plate 220. Positive pressure may be formed, and gas delivery to the upper part of the distribution plate 220 may not be smooth, resulting in poor flow characteristics.

The gas supplier 300 may supply gas to the intestinal chamber 211 of the main reactor 200 so that the raw material powder within the main reactor 200 flows. The supply flow rate of gas supplied from the gas supplier 300 may range from 1 to 100 LPM (Liter/Min). If the gas supply flow rate is less than 1 LPM, it may be difficult to float the raw material powder to the upper end of the main reactor 200 within the main reactor 200, and if the gas supply flow rate is more than 100 LPM, , heavy substances in the raw material powder, along with the valuable metals, float toward the upper end of the main reactor 200, making it difficult to select the valuable metals within the main reactor 200.

In this embodiment, the gas supplied from the gas supplier 300 uses air of 20 to 100 LPM, but the gas supplied from the gas supplier 300 is not limited to this, and the gas supplied from the gas supplier 300 includes oil in the raw material powder in addition to air. Various types of gases that can smoothly classify metals can be used. For example, the gas supplied from the gas supplier 300 may be argon, nitrogen, or a mixed gas containing at least these.

The cyclone unit 400 can separate and recover valuable metals contained in the raw material powder by inducing a swirling flow in the raw material powder. The cyclone unit 400 can receive raw material powder suspended at the upper end of the main reactor 200 and recover valuable metals from the supplied raw material powder.

A fluororesin coating may be formed on the inner wall of the cyclone unit 400 to effectively separate the valuable metal and the cathode material. This is because fine valuable metals may stick to the cyclone unit 400 due to the high static electricity of the valuable metals, thereby reducing the classification efficiency. Accordingly, by forming a fluororesin coating on the inner wall of the cyclone unit 400, static electricity can be minimized and recovery of valuable metals can be effectively improved.

The cyclone unit 400 may be composed of a plurality of cyclones continuously connected to the upper end of the main reactor 200. As an example, the cyclone unit 400 may include a first cyclone 410 and a second cyclone 420 continuously connected to the upper end of the main reactor 200.

The first cyclone 410 may include a first cyclone unit 411, a first recovery unit 412, a first inlet pipe unit 413, and a first discharge pipe unit 414. The first cyclone unit 411 may use centrifugal force to initially select raw material powder containing more valuable metals than a preset amount. Here, the raw material powder containing a preset amount of valuable metal can be understood as the raw material powder supplied through the raw material supplier 100, and the raw material powder containing more valuable metal than the preset amount can be understood as the raw material powder supplied through the raw material supplier ( It can be understood as a raw material powder containing a larger amount of valuable metals than the valuable metals contained in the raw material powder supplied through 100).

One side of the first cyclone unit 411 may be eccentrically connected to the first inlet pipe unit 413. The raw material powder containing more valuable metals than the preset amount introduced into the first cyclone unit 411 is deposited on the inner wall of the first cyclone unit 411 by centrifugal force and by gravity and a downward air flow. It may be lowered to the first recovery unit 412. The first recovery unit 412 may be connected to the lower end of the first cyclone unit 411. The first recovery unit 412 can collect and recover raw material powder containing more valuable metals than a preset amount descending from the first cyclone unit 411. A first recovery valve 416 may be provided between the first cyclone unit 411 and the first recovery unit 412. The first recovery valve 416 can selectively open and close the path from the first cyclone unit 411 to the first recovery unit 412.

The first inlet pipe portion 413 may connect the upper end of the main reactor 200 and one side of the first cyclone portion 411. The first inlet pipe part 413 may be provided with a first inlet valve 415 that opens and closes the movement path from the main reactor 200 to the first cyclone part 411. When the first inlet valve 415 is adjusted to open, the raw material powder floating at the upper end of the main reactor 200 can be supplied to the cyclone unit 400.

The first discharge pipe portion 414 may be disposed at the upper center of the first cyclone portion 411. The first discharge pipe unit 414 may guide the raw material powder rotating upward in the first cyclone unit 411 to the outside of the first cyclone unit 411. The second inlet pipe portion 423 of the second cyclone 420 may be connected to the first discharge pipe portion 414.

The second cyclone 420 may include a second cyclone unit 421, a second recovery unit 422, a second inlet pipe unit 423, and a second discharge pipe unit 424. The second cyclone unit 421 may secondarily select the raw material powder supplied from the first cyclone 410 containing more valuable metals than a preset amount.

One side of the second cyclone unit 421 may be eccentrically connected to the second inlet pipe unit 423. The raw material powder containing more valuable metals than the preset amount introduced into the second cyclone unit 421 is deposited on the inner wall of the second cyclone unit 421 by centrifugal force and by gravity and a downward air flow. It may be lowered to the second recovery unit 422. The second recovery unit 422 may be connected to the lower end of the second cyclone unit 421. The second recovery unit 422 may collect and recover the raw material powder containing more valuable metals than a preset amount descending from the second cyclone unit 421. A second recovery valve 426 may be provided between the second cyclone unit 421 and the second recovery unit 422. The second recovery valve 426 can selectively open and close the path from the second cyclone unit 421 to the second recovery unit 422.

The second inlet pipe portion 423 may connect one side of the first discharge pipe portion 414 of the first cyclone 410 and the second cyclone portion 421. The second inlet pipe portion 423 may be provided with a second inlet valve that opens and closes the movement path from the first cyclone 410 to the second cyclone 420. When the second inlet valve is adjusted to open, the raw material powder discharged to the first cyclone 410 may be supplied to the second cyclone 420.

The second discharge pipe portion 424 may be disposed at the upper center of the second cyclone portion 421. The second discharge pipe unit 424 may guide the raw material powder rotating upward in the second cyclone unit 421 to the outside of the second cyclone unit 421. The second discharge pipe portion 424 may be provided with a discharge valve 427 that selectively opens and closes a path through which raw material powder is discharged to the outside.

The discharge valve 427 can overall adjust the differential pressure and internal pressure of the main reactor 200 and the cyclone unit 400. For example, when the discharge valve 427 is closed, the path through which the raw material powder is discharged to the outside from the second cyclone 420 is blocked, so the internal pressure of the main reactor 200 and the cyclone unit 400 can be increased. there is.

These main reactors 200, the first cyclone 410, and the second cyclone 420 may be supported by the support frame 500. The support frame 500 may include a housing/structure for supporting the main reactor 200, the first cyclone 410, and the second cyclone 420.

[Example]

In this example, neodymium-based waste permanent magnet powder (powder) is leached from the pickling waste liquid, and the powder recovered through the acid recovery process is assumed to be the raw material, and commercial powders are used as iron oxide (Fe ₂ O ₃ ): neodymium oxide (Nd). ₂ O ₃ ) = 95 wt.% : 5 wt.% was mixed and used as a raw material. This ratio leaches the neodymium-based waste permanent magnet powder to 120g/L, which is the iron (Fe) concentration in the pickling waste liquid, and the free acid in the waste liquid at 40g/L, which allows maximum leaching, and the powder recovered after the acid recovery process. It was mixed considering the expected components of the by-product.

The fluidized bed reactor used in the experiment had a diameter of 50 mm and was made of acrylic material so that the inside could be visually observed. A device with a height of 1500 mm was manufactured based on the dispersion plate to secure the powder's flow diffusion distance. To ensure stable separation and recovery of powder after flow, first and second cyclones were installed for recovery. XRF analysis was conducted to show that relatively light iron oxide was collected in a cyclone from the raw material depending on the density of the material.

To derive the fluidization conditions, refer to the modified formula for fine particles in the equation calculated using the Reynolds number, which is the ratio of inertial force and viscous force, which is the minimum fluidization speed, and solid fluid particle characteristics and gas characteristics, which represent fluid particle size and particle density. Table 1 below was calculated.

[Table 1]

Here, the ratio of inertial force and viscous force is called Reynolds number, and the Archimedes number (ratio between buoyancy and momentum), which is a function of solid fluid particle properties and gas properties (gas viscosity and gas density) representing fluid particle size and particle density. The formula for this is used.

And since the particles recovered through the present invention are expected to be uniform, the minimum fluidization speed was recalculated using the particle size information of the actual commercial powder based on the minimum fluidization speed as shown in Table 2 below.

[Table 2]

In the case of Table 1, a typical spray method such as spray drying & roasting may have a certain particle size. Therefore, the particle size range of particles that can be recovered after the ARP process was assumed to be 25 to 50 microns, and in the case of Table 2, a classification experiment was conducted using commercial powder for actual classification. When analyzing the actual commercial powder, Fe oxide was analyzed to be about 1.9 microns and Nd oxide was analyzed to be about 11 microns. Except for the particle size of the material, the remaining variables used for the minimum fluidization speed are the same as previously described.

Referring to Table 2, the differential pressure during flow of powder for classification was measured to be 16.6 ~ 220 mmH2O. This means that the differential pressure occurs differently depending on the flow rate and the pressure of the input gas. When the differential pressure is large, the fluidization behavior of particles is very large, but the classification efficiency is low. When the differential pressure is small, the classification time takes longer, but the classification efficiency is improved to a certain extent. there was.

And as a result of XRF analysis of the mixed commercial powder of initial iron oxide (Fe ₂ O ₃ ) and neodymium oxide (Nd ₂ O ₃ ), Fe ₂ O ₃ was 91.77 wt.% and neodymium oxide (Nd ₂ O ₃ ) was 7.286 wt.%. It was analyzed as a ratio, and as a result of XRF analysis of the powder collected in the first cyclone after fluidized bed classification, the relative density of iron oxide (Fe ₂ O ₃ ) was 93.56 wt.% and neodymium oxide (Nd ₂ O ₃ ) was 5.213 wt.%. It was confirmed that iron oxide (Fe ₂ O ₃ ) with a low value was fluidized and moved to the first cyclone. It was confirmed that the concentration of neodymium oxide (Nd ₂ O ₃ ) was classified by about 28% compared to the mixture.

Meanwhile, referring to FIG. 5, in a modified example of the present invention, the main reactor 200 may include a multi-stage reaction body 210 having different diameters in the longitudinal direction. As an example, the reaction body 210 may have a two-stage structure providing a first-stage body part 212 and a second-stage body part 213 having a diameter larger than the diameter of the first-stage body part 212.

When the main reactor 200 is composed of two stages with different diameter sizes, the flow rate decreases in the portion where the diameter increases, making classification easier. This is because, in the case of a main reactor having a constant diameter, a constant flow rate is maintained up to the top of the main reactor 200, so the flow rate and pressure must be more finely adjusted, and the length of the main reactor 200 must be relatively high. On the other hand, when the main reactor 200 is manufactured in two stages with different diameters, relatively heavy powders re-sedimentation occurs due to the reduced flow rate, so the overall weight of the main reactor 200 is increased compared to the main reactor with a constant diameter. Height may be reduced.

And the reaction body 210 located at the top can be at least twice the diameter of the reaction body 210 located at the bottom. For example, the diameter of the second-stage body portion 213 may be at least twice the diameter of the first-stage body portion 212. Accordingly, the powder moving upward from the first-stage body portion 212 to the second-stage body portion 213 continues to be fluidized from the dispersion plate 220 to the first-stage body portion 212 due to a decrease in flow rate. As this happens, relatively heavy powders re-sedimentation occurs, and relatively light valuable metals can be moved to the first cyclone 410.

When comparing the length of the second-stage body portion 213 and the length of the first-stage body portion 212, the ratio of the length of the second-stage body portion 213 to the length of the first-stage body portion 212 is a 1:1 ratio. Alternatively, the length of the second-stage body portion 213 may be shorter than the length of the first-stage body portion 212. This has little to do with the size of the hydrocyclone. In the case of a hydrocyclone, for recovery efficiency, it can be designed considering the height of the cylindrical part, the height of the conical part, the height of the inlet, the width of the inlet, etc., and can be determined by the particle size and density of the material to be recovered. Additionally, the design of the hydro cyclone may take into account the gas inflow rate, etc., and the design of the hydro cyclone may be more dependent on the operating conditions (flow rate, particle size, density, etc.) than the design value of the reaction body.

In this embodiment, the main reactor 200 has been described as having a two-stage structure with different diameters, but it is not limited thereto, and the main reactor 200 may have a three-stage or more structure with different diameters.

As described above, the present invention can minimize the economic burden required for developing new process technology by using the existing steel process, and uses an acid recovery process system to recycle a large amount of acid in the steel process to remove hydrochloric acid. It can be recovered and reused, and by recovering iron oxide and neodymium oxide as by-products, it is possible to greatly reduce the environmental burden as well as economic benefits. Neodymium oxide can be selectively separated from the mixed powder of iron oxide and neodymium oxide as by-products through a dry process. By doing so, the cost of post-processing can be significantly reduced, and it is a technology that can be applied to most valuable metals including rare earth elements that can leach into hydrochloric acid, which is a pickling waste liquid. It is an eco-friendly multi-platform technology for various materials such as magnesium (Mg) and calcium (Ca). Its scalability and flexibility are excellent, and through this, it can improve the economic feasibility of the rare earth recycling process in resource-poor countries and has excellent advantages such as being able to spread to various industries in the future.

Although embodiments of the present invention have been described above as specific embodiments, this is merely an example, and the present invention is not limited thereto, and should be construed as having the widest scope following the basic ideas disclosed in this specification. A person skilled in the art may implement a pattern of a shape not specified by combining/substituting the disclosed embodiments, but this also does not depart from the scope of the present invention. In addition, a person skilled in the art can easily change or modify the embodiments disclosed based on the present specification, and it is clear that such changes or modifications also fall within the scope of the present invention.

10: Valuable metal recovery method
20: Valuable metal recovery system
100: raw material supplier 200: main reactor
210: reaction body 220: dispersion plate
221: Dispersion hole 300: Gas supplier
400: Cyclone unit 410: First cyclone
411: first cyclone unit 412: first recovery unit
413: first inlet pipe 414: first discharge pipe
415: first inlet valve 416: first recovery valve
420: second cyclone 421: second cyclone unit
422: first recovery part 423: first inlet pipe part
424: first discharge pipe 425: first inlet valve
426: first recovery valve 500: support frame

Claims (11)

An acid recovery step of dissolving the waste permanent magnet powder in the pickling waste liquid and producing raw material powder containing valuable metals from the pickling waste liquid in which the waste permanent magnet powder is dissolved; and
Comprising a valuable metal recovery step of recovering valuable metals from the raw material powder by dry density classifying the raw material powder,
Method for recovering valuable metals from waste permanent magnets. According to claim 1,
The acid recovery step is
Reacting the oxide layer of steel with hydrochloric acid to produce pickling waste liquid;
Dissolving the waste permanent magnet powder in the pickling waste liquid; and
Producing raw material powder containing oxide and regenerated hydrochloric acid from the pickling waste liquid in which the spent permanent magnet powder is dissolved,
Method for recovering valuable metals from waste permanent magnets. According to claim 2,
The oxide is
Containing iron oxide (Fe ₂ O ₃ ) and neodymium oxide (Nd ₂ O ₃ ),
Method for recovering valuable metals from waste permanent magnets. According to claim 2,
The step of producing the pickling waste liquid is,
To enable additional dissolution of the waste permanent magnet powder in the pickling waste liquid, providing a pickling waste liquid capable of additional dissolution of free acid up to a limit concentration,
The step of dissolving the waste permanent magnet powder in the pickling waste liquid,
Dissolving the waste permanent magnet powder in the pickling waste liquid using the free acid to the above limit concentration,
The limiting concentration is a concentration lower than the concentration of iron contained in the oxidized layer that is maximally soluble in hydrochloric acid,
Method for recovering valuable metals from waste permanent magnets. According to claim 4,
The step of producing the pickling waste liquid is,
When the critical concentration is 160 g/L, the iron concentration of the pickling waste liquid is maintained at 120 g/L to enable additional dissolution of 40 g/L of the free acid,
The step of dissolving the waste permanent magnet powder in the pickling waste liquid,
Dissolving the waste permanent magnet powder in the pickling waste liquid in which 40 g/L of the free acid is dissolved,
Method for recovering valuable metals from waste permanent magnets. According to claim 1,
The valuable metal recovery step is
Supplying raw material powder to the main reactor;
Supplying gas to the main reactor to allow raw material powder to flow in the main reactor;
supplying raw material powder suspended at the upper end of the main reactor to a cyclone unit; and
Comprising the step of recovering valuable metals from the raw material powder in the cyclone unit,
Method for recovering valuable metals from waste permanent magnets. A raw material supply machine for supplying raw material powder;
a main reactor providing a long chamber extending in the vertical direction so that the raw material powder can flow in the vertical direction;
a gas supplier that supplies gas to the intestinal chamber so that the raw material powder flows in the main reactor; and
A cyclone unit connected to the upper end of the main reactor, receiving raw material powder suspended at the upper end of the main reactor and recovering valuable metals from the raw material powder,
Valuable metal recovery system for waste permanent magnets. According to claim 7,
The main reactor is
A reaction body in which the raw material supplier is connected to the upper part, the gas supplier is connected to the lower part, and the intestinal chamber is provided therein; and
Disposed at the bottom of the intestinal chamber, comprising a dispersion plate providing a plurality of dispersion holes to allow the gas to pass through,
Valuable metal recovery system for waste permanent magnets. According to claim 8,
The cyclone unit is
Comprising a first cyclone and a second cyclone continuously connected to the upper end of the main reactor,
Valuable metal recovery system for waste permanent magnets. According to clause 9,
The first cyclone is
A first cyclone unit that uses centrifugal force to primarily select raw material powder containing more valuable metals than a preset amount;
a first recovery unit connected to the bottom of the first cyclone unit to collect the initially selected raw material powder;
A first inlet pipe section connecting the upper end of the main reactor and the first cyclone section; and
It includes a first discharge pipe section that guides the raw material powder rotating upward in the first cyclone section to the outside of the first cyclone section,
The second cyclone is
a second cyclone unit that uses centrifugal force to secondarily select raw material powder containing more valuable metals than a preset amount;
a second recovery unit connected to the bottom of the second cyclone unit to collect the secondary selected raw material powder;
a second inlet pipe connecting the first discharge pipe and the second cyclone; and
Comprising a second discharge pipe unit that guides the raw material powder rotating upward in the second cyclone unit to the outside of the second cyclone unit,
Valuable metal recovery system for waste permanent magnets. According to claim 8,
The reaction body is
1st stage body part; and
It includes a second-stage body part obliquely connected to the upper part of the first-stage body part so as to have a diameter larger than that of the first-stage body part,
The diameter of the second-stage body portion is more than two times larger than the diameter of the first-stage body portion,
Valuable metal recovery system for waste permanent magnets.