Method for purifying metal scandium through vacuum magnetic suspension clean smelting

Abstract

The invention belongs to the technical field of rare earth and semiconductor raw materials, and discloses a method for purifying metal scandium through vacuum magnetic suspension clean smelting. The purification method comprises the following steps that a scandium metal material subjected to calcium thermal reduction is put into a vacuum magnetic suspension smelting furnace, vacuumizing is conducted firstly, then inert protective gas is introduced, electric heating smelting is conducted, after all the materials form a liquid state, refining purification is conducted through electromagnetic stirring and heat preservation, and after purification is completed, cooling is conducted to obtain a scandium metal ingot; and the obtained metal scandium ingot is repeatedly put into the vacuum magnetic suspension smelting furnace to be repeatedly smelted, refined and purified, and purified metal scandium is obtained after cooling. The purification method provides a new thought for preparation and purification of metal scandium, repeated distillation is not needed, and energy consumption is reduced. Carbon, oxygen, nitrogen, hydrogen, calcium, manganese, iron and the like can be removed, high-purity metal scandium can be prepared, and the purification method is high in treatment scale selectivity.

Description

Technical Field

[0001] The invention belongs to the technical field of rare earth and semiconductor raw materials, and in particular relates to a method for cleanly melting and purifying metal scandium through vacuum magnetic suspension. Background Art

[0002] Metal scandium has good properties and has been used in many fields such as aerospace, nuclear technology, electronics and chemical industry, semiconductors, solid fuel cells, etc.

[0003] There are three methods for preparing metal scandium: intermediate alloy method, molten salt electrolysis method, and direct metal thermal reduction method. For example, patent CN118345257A discloses a method for purifying 5N metal scandium based on vacuum calcium thermal reduction technology, wherein the treated crude scandium oxide product is added with flux and heated to a molten state; pure calcium powder is added and reduced in an inert gas protective atmosphere; vacuum distillation is performed to obtain a high-purity scandium solid. Patent CN 111961886 A discloses placing reduced scandium with a purity of more than 90% in a vacuum carbon tube furnace, and using a low temperature section of 1000 to 1400°C and a high temperature section of 1600 to 1800°C for segmented distillation and purification; the rare earth metal scandium obtained by segmented distillation and purification is further subjected to at least one segmented distillation and purification to obtain a high-purity rare earth metal scandium with a purity of 3N to 4N. However, at high temperatures, scandium has a strong corrosive effect on crucible materials. Scandium in the reduced slag is not easy to recover, and multiple vacuum distillation processes are needed to further remove impurities. However, the vacuum distillation process has problems such as high energy consumption, low production efficiency, and high cost, which affect the quality and market competitiveness of the product. Summary of the invention

[0004] In view of the shortcomings and deficiencies of the above prior art, the purpose of the present invention is to provide a method for purifying metal scandium by vacuum magnetic suspension clean smelting. The method of the present invention can achieve high temperature (the theoretical maximum smelting temperature of magnetic suspension smelting can reach 3500°C), high purity (5N and above), and high efficiency to purify metal scandium by magnetic suspension smelting.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A method for cleanly melting and purifying metal scandium by vacuum magnetic suspension comprises the following steps:

[0007] The metal scandium material after calcium thermal reduction is put into a vacuum magnetic levitation melting furnace, first evacuated, then introduced with inert protective gas, and melted by electric heating. After all the materials are in liquid state, they are refined and purified by electromagnetic stirring. After purification, they are cooled to obtain a metal scandium ingot; the obtained metal scandium ingot is repeatedly put into the vacuum magnetic levitation melting furnace for repeated smelting and refining and purification, and purified metal scandium is obtained after cooling.

[0008] Furthermore, the purity of the metal scandium material after calcium thermal reduction is 3N-3.5N.

[0009] Furthermore, the vacuuming refers to vacuuming to a pressure of 1.0 to 8.0×10 -3 Between Pa.

[0010] Furthermore, the inert protective gas refers to nitrogen, argon or helium; the pressure of the inert protective gas introduced is 0.001-0.003 MPa.

[0011] Furthermore, the power of the electric heating smelting is 260-320 kW, and the temperature of the electric heating smelting is 1800-2200°C.

[0012] Furthermore, the temperature of the heat preservation, refining and purification is 1800-2200° C., and the time of the heat preservation, refining and purification is 5-10 minutes.

[0013] Furthermore, the electric heating smelting and heat preservation refining and purification use a water-cooled copper crucible. The material in the molten state does not contact the crucible or only partially contacts it, and the crucible does not contaminate the material.

[0014] Furthermore, the pressure of the inert protective gas is adjusted to 0.01-0.03 MPa during the heat preservation, refining and purification process. The present invention can differentially adjust the pressure difference by controlling the amount of inert gas introduced, so as to facilitate the removal of different impurities.

[0015] Furthermore, the cooling refers to rapidly reducing power within 45 to 60 seconds and then rapidly cooling by frequency conversion to form a metal scandium ingot, or casting the metal scandium melt into a water-cooled mold within 5 to 6 seconds and then rapidly cooling by frequency conversion to form a metal scandium ingot. The above rapid cooling can prevent secondary adsorption of impurities.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The method of the present invention can prepare high-purity metal scandium, remove carbon, oxygen, nitrogen, hydrogen, calcium, manganese, iron, etc., and improve the purity of the product.

[0018] (2) The vacuum magnetic levitation smelting furnace used in the present invention has a strong electromagnetic stirring effect in the molten pool, which ensures the uniformity of purification.

[0019] (3) The purification method of the present invention has high selectivity in processing scale, and can smelt from a few kg to hundreds of kg.

[0020] (4) The purification method of the present invention provides a new idea for the preparation and purification of metal scandium, which does not require repeated distillation and reduces energy consumption. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0022] Example 1

[0023] (1) The metal scandium material (whose impurity element content is shown in Table 1) after calcium thermal reduction is placed in a water-cooled copper crucible of a vacuum magnetic levitation melting furnace.

[0024] (2) The equipment is vacuumed to 1.0-2.0×10 -3 Pa, and then introduce inert protective argon gas with a pressure of 0.003MPa into the furnace.

[0025] (3) Power heating, the temperature rises to 1800-2000℃, the power rises to 280-300kw, and after all the metal scandium is melted, the power is increased to carry out strong electromagnetic stirring, heat preservation, refining and purification for 5 minutes. During the refining process, protective argon gas is filled into the furnace to adjust the pressure to 0.03MPa.

[0026] (4) After refining, the power is rapidly reduced within 45 seconds and then the frequency is changed to rapidly cool to form a metal scandium ingot.

[0027] (5) The scandium metal ingot is turned over and remelted. The scandium metal ingot is placed upside down and added to the magnetic suspension melting furnace. After melting and refining with increased power and heat preservation according to step (3), a clean scandium metal melt is obtained. The power is quickly reduced and the frequency is changed again for rapid cooling to obtain the scandium metal.

[0028] The impurity element content of the purified scandium metal is shown in Table 1.

[0029] Example 2

[0030] (1) The metal scandium material (whose impurity element content is shown in Table 1) after calcium thermal reduction is placed in a water-cooled copper crucible of a vacuum magnetic levitation melting furnace.

[0031] (2) The equipment is vacuumed to 2.0-5.0×10 -3 Pa, and then introduce inert protective argon gas with a pressure of 0.002MPa into the furnace.

[0032] (3) Power heating, the temperature rises to 1800-2000℃, the power rises to 260-310kw, and after all the metal scandium is melted, the power is increased to carry out strong electromagnetic stirring, heat preservation, refining and purification for 10 minutes. During the refining process, protective argon gas is filled into the furnace to adjust the pressure to 0.02MPa.

[0033] (4) After refining, the scandium metal melt is cast into a water-cooled mold within 6 seconds, and then rapidly cooled by variable frequency to form a scandium metal ingot.

[0034] (5) The scandium metal ingot is turned over and remelted. After the scandium metal ingot is demolded and cleaned, it is inverted and added into the magnetic suspension melting furnace. After melting and refining with increased power and heat preservation according to step (3), a clean scandium metal melt is obtained. After rapidly reducing power and rapidly cooling again with variable frequency, the scandium metal is obtained.

[0035] The impurity element content of the purified scandium metal is shown in Table 1.

[0036] Example 3

[0037] (1) The metal scandium material (whose impurity element content is shown in Table 1) after calcium thermal reduction is placed in a water-cooled copper crucible of a vacuum magnetic levitation melting furnace.

[0038] (2) The equipment is vacuumed to 5.0-8.0×10 -3 Pa, and then introduce inert protective argon gas with a pressure of 0.001 MPa into the furnace.

[0039] (3) Power is supplied for heating, the temperature is raised to 1800-2000°C, the power is increased to 300-320kw, and after all the metal scandium is melted, the power is increased to carry out strong electromagnetic stirring, heat preservation, refining and purification for 8 minutes. During the refining process, protective argon gas is filled into the furnace to adjust the pressure to 0.01MPa.

[0040] (4) After the refining is completed, the power is rapidly reduced within 60 seconds and then the power is rapidly increased to 300-320 kW for secondary smelting. After heat preservation and power increase refining, the power is rapidly reduced and frequency conversion cooling is performed to obtain a metal scandium ingot.

[0041] (5) The scandium metal ingot is turned over and remelted. The scandium metal ingot is placed upside down and added into a magnetic levitation melting furnace. After remelting and refining with increased power and heat preservation, a clean scandium metal melt is obtained. The scandium metal melt is quickly cast into a water-cooled mold and then rapidly cooled by frequency conversion to obtain the scandium metal.

[0042] The impurity element content of the purified scandium metal is shown in Table 1.

[0043] Table 1. Comparison of impurity content before and after purification

[0044]

[0045]

[0046] It can be seen from the results in Table 1 that the method of the present invention can achieve high-efficiency purification of metal scandium.

[0047] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for clean smelting and purifying metal scandium by vacuum magnetic suspension, characterized in that: The steps include: The metal scandium material after calcium thermal reduction is put into a vacuum magnetic levitation melting furnace, first evacuated, then introduced with inert protective gas, and melted by electric heating. After all the materials are in liquid state, they are refined and purified by electromagnetic stirring. After purification, they are cooled to obtain a metal scandium ingot; the obtained metal scandium ingot is repeatedly put into the vacuum magnetic levitation melting furnace for repeated smelting and refining and purification, and purified metal scandium is obtained after cooling.

2. The method for clean smelting and purifying scandium metal by vacuum magnetic suspension according to claim 1, characterized in that: The purity of the metal scandium material after calcium thermal reduction is 3N-3.5N.

3. The method for clean smelting and purifying metal scandium by vacuum magnetic suspension according to claim 1, characterized in that: The vacuuming refers to vacuuming to a pressure of 1.0 to 8.0×10 -3 Between Pa.

4. The method for clean smelting and purifying metal scandium by vacuum magnetic suspension according to claim 1, characterized in that: The inert protective gas refers to nitrogen, argon or helium; the pressure of the inert protective gas introduced is 0.001-0.003 MPa.

5. The method for clean smelting and purifying metal scandium by vacuum magnetic suspension according to claim 1, characterized in that: The power of the electric heating smelting is 260-320kw, and the temperature of the electric heating smelting is 1800-2200℃.

6. The method for clean smelting and purifying metal scandium by vacuum magnetic suspension according to claim 1, characterized in that: The temperature of the heat preservation, refining and purification is 1800-2200° C., and the time of the heat preservation, refining and purification is 5-10 minutes.

7. The method for clean smelting and purifying metal scandium by vacuum magnetic suspension according to claim 1, characterized in that: The electric heating smelting and heat preservation refining and purification use a water-cooled copper crucible.

8. The method for clean smelting and purifying scandium metal by vacuum magnetic suspension according to claim 1, characterized in that: During the heat preservation, refining and purification process, the pressure of the inert protective gas is adjusted to 0.01-0.03 MPa.

9. The method for clean smelting and purifying metal scandium by vacuum magnetic suspension according to claim 1, characterized in that: The cooling refers to rapidly reducing power within 45 to 60 seconds and then rapidly cooling by frequency conversion to form a metal scandium ingot, or casting the metal scandium melt into a water-cooled mold within 5 to 6 seconds and then rapidly cooling by frequency conversion to form a metal scandium ingot.

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