Metal treatment method using thermal reduction process

Abstract

The present invention relates to a metal treatment method whereby a target metal can be obtained. The metal treatment method comprises the steps of: reacting a metal oxide, a salt bath agent, and a reducing agent in a reaction space of a reaction tank at a first temperature to obtain a liquid salt solution and a liquid metal phase containing a reduced metal, wherein the liquid metal phase is located in the lower portion of the reaction space, and the salt solution is located in the upper portion of the reaction space; lowering the temperature of the reaction space to a second temperature lower than the first temperature to maintain the metal phase in a liquid phase and change the salt solution into a higher viscosity state; and selectively discharging the liquid metal phase from the reaction space.

Description

Metal treatment method using a thermal reduction process

[0001] The present invention relates to a method for treating metal using a thermal reduction process.

[0002] Permanent magnets are magnets that generate and maintain a stable magnetic field without receiving external electrical energy. They are being used in various fields recently, and are particularly widely used in the IT, automobile, and home appliance fields.

[0003] Among them, neodymium magnets have excellent magnetic properties, high strength, and low production costs, and are used in various industrial products, and production volume continues to increase in line with demand.

[0004] Neodymium (Nd) is the second most common rare earth element after cerium. It oxidizes rapidly in air and reacts rapidly with hot water to form hydroxides. Because neodymium has a strong affinity for oxygen, research is ongoing into methods for stably reducing it and increasing the efficiency of neodymium production.

[0005] An object of the present invention is to provide a method for treating metal using a thermal reduction process.

[0006] The present invention relates to a metal processing method capable of obtaining a target metal, comprising: a step of reacting a metal oxide, a dye bath, and a reducing agent at a first temperature in a reaction space of a reaction tank to obtain a liquid dye solution and a liquid metal phase including a reduced metal; wherein the liquid metal phase is located at a lower portion of the reaction space, and the dye solution is located at an upper portion of the reaction space; a step of lowering the temperature of the reaction space to a second temperature lower than the first temperature, thereby maintaining the metal phase in a liquid phase and changing the dye solution into a state with increased viscosity; and a step of selectively discharging the liquid metal phase from the reaction space.

[0007] After obtaining the above metal phase, the method may further include a step of adjusting the temperature of the reaction space to a third temperature and a step of adding a first regulator that adjusts the melting point of the metal phase at the third temperature to the reaction space.

[0008] The third temperature is between the first temperature and the second temperature, and the third temperature may be a temperature of +300°C of the melting point of the first regulator to -30°C of the boiling point of the first regulator.

[0009] The melting point of the first regulator may be lower than the melting point of the metal phase, and the vapor pressure of the first regulator at the third temperature may be higher than the vapor pressure of the metal phase.

[0010] The above metal oxide may include a rare earth metal oxide.

[0011] The above metal oxide may include neodymium oxide.

[0012] The above first regulator may be selected from zinc (Zn), tin (Sn), and lead (Pb).

[0013] The first regulator comprises zinc (Zn), and the first regulator can react with the metal phase to form a liquid alloy.

[0014] The above dyeing agent may include at least one of calcium chloride (CaCl2) and calcium fluoride (CaF2), and the reducing agent may include calcium (Ca).

[0015] The above dyeing agent may include calcium chloride (CaCl2), and the dyeing solution may include calcium oxide (CaO) and calcium chloride (CaCl2).

[0016] The above calcium (Ca) is converted into calcium oxide (CaO) in the above reaction, and the salt solution may contain calcium oxide (CaO) and calcium chloride (CaCl2) in a weight ratio of 10:90 to 20:80.

[0017] The above liquid alloy contains ZnNd, and the above liquid alloy may contain Zn and Nd in a weight ratio of 6:94 to 22:78.

[0018] The above first temperature may be 1050°C to 1300°C.

[0019] The second temperature may be 600°C to 850°C.

[0020] The third temperature may be 830°C to 870°C.

[0021] The above viscosity increase state may include a solid state or a liquid state having a viscosity 2 to 1000 times greater than that of the ZnNd at the second temperature.

[0022] The step of obtaining the above-mentioned dye solution and metal phase may further include a step of converting the dye bath and the metal oxide into a liquid phase in the reaction space before the reaction; and a step of introducing the reducing agent after the liquid phase conversion.

[0023] After obtaining the above metal phase, a step of adding a second regulator for controlling the melting point of the salt solution to the reaction space is further included, and the second regulator may include calcium fluoride (CaF2).

[0024] After the above discharge step, a step of vacuum distilling the liquid alloy to volatilize the first regulator may be further included.

[0025] The above vacuum distillation can be performed at a temperature of +50°C to +300°C above the melting point of the alloy.

[0026] The above vacuum distillation is performed at a pressure of 5x10 -1 Thor 9x10 -3 It can be performed in Thor.

[0027] In the above discharge step, the metal phase can be discharged to the bottom of the reaction tank by free fall.

[0028] The above discharge step is performed through the discharge unit,

[0029] The above-mentioned boiling part is,

[0030] It may include a first part connected to the lower part of the above-mentioned reaction tank and having a cross-sectional area that becomes narrower as it goes downward; and a second part connected from the first part toward the lower part and having a constant cross-sectional area.

[0031] The above discharge step is performed through a tapping unit, and the tapping unit may include a first section connected to the lower portion of the reaction tank and having a cross-sectional area that becomes narrower as it goes downward; a second section located below the first section; a third section located below the second section; a first heating means for heating the first section; a cooling means for cooling the second section; and a second heating means for heating the third section.

[0032] The above discharge can be achieved by a combination of operation of the heating means and operation of the cooling means.

[0033] According to the present invention, a method for processing metal using a heat reduction process is provided.

[0034] Figure 1 is a diagram illustrating a metal processing method according to one embodiment of the present invention.

[0035] Figure 2 is a flowchart showing a metal processing method according to one embodiment of the present invention.

[0036] Figure 3 shows the change in temperature over time in a reaction tank in a metal processing method according to one embodiment of the present invention.

[0037] Figure 4 illustrates a discharge unit according to one embodiment of the present invention.

[0038] Figure 5 shows another example of a discharge unit according to one embodiment of the present invention.

[0039] Figure 6 illustrates a lower discharge in a metal processing method according to one embodiment of the present invention.

[0040] Hereinafter, the intent, function, and effects of the present invention will be described in detail through embodiments of the present invention and specific descriptions and examples for facilitating understanding and implementation thereof. However, as mentioned above, the following descriptions and examples are provided as examples to aid understanding of the present invention and are not intended to limit or limit the scope of the rights.

[0041] Before describing the present invention in detail, it should be noted that the terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, and should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the meaning of the term in order to describe his or her own invention in the best way.

[0042] Therefore, the configuration of the embodiments described in this specification is only one of the most preferred embodiments of the present invention, and does not represent all of the technical ideas of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist that can replace them at the time of filing.

[0043] In this specification, singular expressions include plural expressions unless the context clearly dictates otherwise. For example, terms such as “comprises,” “includes,” or “has” should be understood to indicate the presence of a specified feature, number, step, component, or combination thereof, but not to preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0044] The present invention will be described in more detail with reference to the drawings below.

[0045] In the following description, the 'metal phase' can be explained as, for example, containing only neodymium (Nd) after the reaction, an alloy state such as ZnNd when the melting point is controlled by adding the first regulator, and again containing only neodymium (Nd) when the alloy is vacuum distilled.

[0046] A metal processing method according to an embodiment of the present invention is described through FIGS. 1 to 3.

[0047] FIG. 1 is a diagram illustrating steps in a metal processing method according to an embodiment of the present invention, FIG. 2 is a flowchart illustrating a metal processing method according to an embodiment of the present invention, and FIG. 3 illustrates temperature changes over time in a reaction tank in a metal processing method according to an embodiment of the present invention.

[0048] Referring to FIGS. 1 and 2, first, a metal oxide, a dye bath, and a reducing agent are reacted at a first temperature in the reaction space of the reactor to obtain a liquid dye solution and a liquid metal phase containing a reduced metal. (S100)

[0049] In this embodiment, the metal oxide is exemplified by neodymium oxide (Nd2O3), but is not limited thereto, and the metal oxide may be another metal, and in particular, may be a rare earth metal oxide.

[0050] At least one of calcium chloride (CaCl2) and calcium fluoride (CaF2) may be used as the dye, and calcium chloride (CaCl2) is preferably used.

[0051] The metal oxide and dye bath are in a liquid state through temperature control in the reaction space.

[0052] The reducing agent includes calcium (Ca). In other embodiments, it may be replaced with an alkali metal that is highly reactive with oxygen.

[0053] Referring to Figure 1, first, a metal oxide, a dye bath, and a reducing agent are introduced into the reaction space of the reactor and reacted at a first temperature. (①)

[0054] Referring to FIG. 3, the first temperature may be any temperature above which the metal oxide, dye, and reducing agent can be dissolved within the reaction space. For example, the first temperature may be selected from a temperature of 1050 to 1300°C, 1100 to 1250°C, 1150 to 1250°C, or 1150 to 1200°C.

[0055] Afterwards, a liquid salt solution and a liquid metal phase containing the reduced metal are obtained through the reaction. (③) Here, due to the difference in density, the liquid metal phase is located at the bottom of the reaction space, and the salt solution is located at the top of the reaction space.

[0056] Here, the liquid salt solution contains calcium oxide (CaO) and calcium chloride (CaCl2).

[0057] Calcium (Ca) used as a reducing agent is at least partially converted to calcium oxide (CaO) in the reaction.

[0058] Although not limited thereto, the salt solution may contain 10 to 30 wt% of calcium oxide (CaO) and 70 to 90 wt% of calcium chloride (CaCl2) based on the total weight.

[0059] In another embodiment, a liquid metal phase containing a liquid salt solution and a reduced metal can be obtained through the following steps.

[0060] First, metal oxide and dye are added to the reaction space to convert it into a liquid phase. (①)

[0061] After the liquid phase is converted, a reducing agent is added. (②)

[0062] Afterwards, the metal oxide, dyeing agent, and reducing agent in the reaction space are reacted at the first temperature to obtain a liquid dye solution and a liquid metal phase containing the reduced metal. (③)

[0063] After obtaining a liquid metal phase, the temperature of the reaction space is adjusted to a third temperature, and a first regulator that adjusts the melting point of the metal phase at the third temperature is added to the reaction space. (S200)

[0064] The third temperature is between the first temperature and the second temperature described below, and may be selected from a temperature of +300°C above the melting point of the first regulator to -30°C above the boiling point of the first regulator. For example, the third temperature may be a temperature of about 830 to 870°C, about 830 to 860°C, or about 840 to 850°C.

[0065] The first regulator can be selected from zinc (Zn), tin (Sn), and lead (Pb), and the following description will illustrate the use of zinc (Zn). (④)

[0066] In the step where the melting point of the metal phase is controlled by the first regulator, the melting point of the first regulator is lower than that of the metal phase, and the vapor pressure at the third temperature is higher than that of the metal phase.

[0067] Referring to Figure 1, by introducing the first regulator, the metal phase and the first regulator in the reaction space react to form a liquid alloy. (⑤)

[0068] In this embodiment, the liquid alloy includes ZnNd.

[0069] Although not limited thereto, the liquid alloy may contain 6 to 22 wt% zinc (Zn) and 78 to 94 wt% neodymium (Nd) based on the total weight.

[0070] Although not shown, in another embodiment, after obtaining a liquid metal phase, a step of adding a second regulator to the reaction space to adjust the melting point of the salt solution may be further performed. In this case, the second regulator includes calcium fluoride (CaF2).

[0071] Next, the temperature of the reaction space is lowered to a second temperature lower than the first temperature, so that the metal phase remains in a liquid state and the salt solution changes to a state with increased viscosity. (S300)

[0072] The increased viscosity state includes a liquid state in which the liquid salt solution has a viscosity of 2 to 2000 times, 2 to 1500 times, 2 to 1300 times, or 2 to 1000 times greater than that of the alloy in the solid state or at the second temperature.

[0073] Referring to FIG. 3, the second temperature is a temperature lower than the first temperature, and is a temperature that increases the viscosity of the dye solution. For example, the second temperature may be selected from a temperature of 600 to 850°C, 600 to 830°C, 700 to 830°C, or 700 to 800°C.

[0074] Afterwards, the liquid metal phase is selectively discharged from the reaction space. (S400)

[0075] In this embodiment, the discharge is that the metal phase is discharged to the bottom of the reaction tank by free fall.

[0076] FIG. 4 illustrates a discharge unit according to one embodiment of the present invention, and FIG. 5 illustrates another example of a discharge unit according to one embodiment of the present invention.

[0077] Referring to FIG. 4, the discharge step is performed through a discharge unit (100) that is connected to the lower part of the reactor and includes a first part (110) whose cross-sectional area becomes narrower as it goes downward and a second part (120) that is connected from the first part downward and has a constant cross-sectional area.

[0078] Referring to FIGS. 5 and 6, the discharge step is performed through a discharge unit (200) that is connected to the lower part of the reactor and includes a first section (210) whose cross-sectional area becomes narrower as it goes lower, a second section (220) located below the first section (210), a third section (230) located below the second section (220), a first heating means (240) for heating the first section (210), a cooling means (250) for cooling the second section, and a second heating means (260) for heating the third section.

[0079] Here, the discharge is achieved by a combination of the operation of the heating means (240, 260) and the operation of the cooling means (250).

[0080] Next, after the discharge step, a step is performed to volatilize the first regulator by vacuum distilling the liquid alloy. (S500)

[0081] Through the above process, the first regulator is volatilized, resulting in only high-purity neodymium (Nd). Although not shown, a further step of cooling and capturing the volatilized first regulator through vacuum distillation may be performed.

[0082] Vacuum distillation is performed at a temperature of +50°C to +300°C above the melting point of the liquid metal, for example, a temperature of 1050 to 1300°C, 1100 to 1250°C, 1150 to 1250°C or 1150 to 1200°C.

[0083] Vacuum distillation is a process where the pressure is 5x10 -1 Thor 9x10 -3 It is performed in Thor, and high purity neodymium (Nd) can be obtained by removing ball impurities through vacuum distillation.

[0084] Hereinafter, the present invention will be described in more detail through specific experimental examples.

[0085] Example

[0086] 1000 g of metal oxide Nd2O3 powder and 2830 g of dyeing agent CaCl2 granules were added to a reaction tank and heated to the first temperature of 1200°C to prepare a liquid dye solution. Thereafter, 540 g of reducing agent Ca granules were added at 1200°C and a reduction reaction was performed for 2 hours to produce liquid Nd metal.

[0087] Next, after primary cooling to the third temperature of 850℃, 210g of the first regulator Zn granules were added to the reactor and maintained for 30 minutes to produce a liquid metal phase (ZnNd). Afterwards, only the liquid ZnNd was discharged to the bottom at the second temperature of 800℃ and recovered.

[0088] Afterwards, the liquid ZnNd was vacuum distilled to volatilize the first regulator, Zn, and recover the final target metal, Nd.

[0089] Comparative example

[0090] 1000 g of metal oxide Nd2O3 powder and 2830 g of dyeing agent CaCl2 granules were added to a reaction tank and heated to the first temperature of 1200°C to prepare a liquid dye solution. Thereafter, 540 g of reducing agent Ca granules were added at 1200°C and a reduction reaction was performed for 2 hours to produce liquid Nd metal.

[0091] Next, the first cooling was performed to the third temperature of 850℃, and then the first regulator, Zn, was not added and maintained for 30 minutes. Then, the generated metal phase was discharged to the bottom and recovered.

[0092] Experimental example: Amount and reduction rate of metal produced

[0093] The amount of metal phase produced in the examples and comparative examples was measured. In addition, the amount of metal phase produced was compared to the amount of raw material introduced into the reactor, and the metal reduction rate was calculated using the following formula.

[0094] [Calculation formula]

[0095] Weight of recovered metal / Weight of theoretical metal Nd * 100%

[0096] The measurement results are shown in Table 1 below.

[0097] Amount of metal formed (unit: g)Metal reduction rate (unit: %)Example 849g99.0%Comparative example 825g92.7%

[0098] As described in Table 1, the amount of metal phase produced according to the example was 849 g and the metal reduction rate was 99.0%. In comparison, the amount of metal phase produced in the comparative example without adding the first regulator, Zn, was 825 g and the metal reduction rate was 92.7%. In other words, it can be seen that the amount of metal phase produced and the metal reduction rate increased when the first regulator was added.

[0099] Above, one embodiment of the present invention has been described, but a person having ordinary skill in the art will be able to modify and change the present invention in various ways by adding, changing, deleting or adding components, etc., within the scope that does not depart from the spirit of the present invention described in the claims, and this will also be considered to be included within the scope of the rights of the present invention.

Claims

1. Regarding a metal processing method capable of obtaining a target metal, A step of reacting a metal oxide, a dye bath, and a reducing agent in a reaction space of a reaction tank at a first temperature to obtain a liquid dye solution and a liquid metal phase including a reduced metal; wherein the liquid metal phase is located at the lower portion of the reaction space, and the dye solution is located at the upper portion of the reaction space. A step of lowering the temperature of the reaction space to a second temperature lower than the first temperature, thereby maintaining the metal phase in a liquid state and changing the salt solution into a state with increased viscosity; and A metal processing method, comprising: a step of selectively discharging the liquid metal phase from the reaction space.

2. In paragraph 1, After obtaining the above metal statue, A metal processing method further comprising a step of controlling the temperature of the reaction space to a third temperature and a step of adding a first controlling agent that controls the melting point of the metal phase at the third temperature to the reaction space.

3. In paragraph 2, The third temperature is between the first temperature and the second temperature, A metal processing method wherein the third temperature is a temperature ranging from +300°C to -30°C of the melting point of the first regulator.

4. In paragraph 3, The melting point of the above first regulator is lower than the melting point of the above metal phase, A metal treatment method wherein the vapor pressure of the first regulator at the third temperature is higher than the vapor pressure of the metal phase.

5. In paragraph 4, A method for treating a metal, wherein the metal oxide comprises a rare earth metal oxide.

6. In paragraph 4, The above first regulator comprises zinc (Zn), A metal treatment method in which the first regulator reacts with the metal phase to form a liquid alloy.

7. In paragraph 6, The above dyeing agent contains calcium chloride (CaCl2), The above reducing agent contains calcium (Ca), The above-mentioned salt solution is a metal treatment method containing calcium oxide (CaO) and calcium chloride (CaCl2).

8. In paragraph 7, The above calcium (Ca) is converted into calcium oxide (CaO) in the above reaction, A metal treatment method wherein the above-mentioned salt solution contains calcium oxide (CaO) and calcium chloride (CaCl2) in a weight ratio of 10:90 to 20:

80.

9. In paragraph 8, The above liquid alloy contains ZnNd, A metal treatment method wherein the liquid alloy contains Zn and Nd in a weight ratio of 6:94 to 22:

78.

10. In paragraph 9, The above first temperature is 1050℃ to 1300℃, The above second temperature is 600℃ to 850℃, A metal treatment method wherein the third temperature is 830°C to 870°C.

11. In paragraph 1, The steps of obtaining the above dye and metal phase are: A step of converting the dye and the metal oxide into a liquid phase in the reaction space before the reaction; and A metal treatment method further comprising a step of introducing a reducing agent after the liquid conversion.

12. In paragraph 1, After obtaining the above metal phase, the method further includes adding a second regulator for controlling the melting point of the dye solution to the reaction space. A metal treatment method wherein the second regulator comprises calcium fluoride (CaF2).

13. In paragraph 12, After the above discharge step, a step of vacuum distilling the liquid alloy to volatilize the first regulator is further included. The above vacuum distillation is, 5x10 at a temperature between +50℃ and +300℃ above the melting point of the above alloy. -1 Thor 9x10 -3 A method of metal processing performed in Thor.

14. In paragraph 1, In the above discharge step, The above metal is discharged to the bottom of the reaction tank by free fall, The above discharge step is performed through the discharge unit, The above-mentioned boiling point is, A first part connected to the lower part of the above reactor and having a cross-sectional area that narrows towards the lower part; and A metal processing method comprising: a second part connected downward from the first part and having a constant cross-sectional area; 15. In paragraph 1, The above discharge step is performed through the discharge unit, The above-mentioned boiling point is, A first section connected to the lower part of the above reactor and having a cross-sectional area that narrows towards the lower part; A second section located below the first section; A third section located below the second section; A first heating means for heating the above section 1; A cooling means for cooling the second section; and Includes a second heating means for heating the third section, The above emissions are, A metal processing method achieved by a combination of operation of the above heating means and operation of the above cooling means.

Images