Optimization method for improving yield of rare earth lanthanum in 25 kg vacuum induction furnace smelting

Abstract

The invention discloses an optimization method for improving the yield of rare earth lanthanum in 25kg vacuum induction furnace smelting, which comprises the following steps of: controlling the following process parameters in the heating and melting process in a vacuum induction furnace: pumping air in the vacuum induction furnace to be below 35Pa, filling argon to be 0.55 standard atmospheric pressure, heating for 3 minutes under the low power of 30kw, and after furnace charge is slightly red, cooling to the room temperature to obtain the rare earth lanthanum after the furnace charge is slightly red. The method comprises the following steps of: adding a furnace material into the molten steel, adjusting the power to 50kw, heating for 2 minutes, finally heating at high power of 110kw until the furnace material is completely molten, then adding a lanthanum-iron alloy, adjusting to 55kw after the lanthanum-iron alloy is molten, heating for 55 seconds at low power, and ensuring that the rare earth lanthanum is uniform in the molten steel. According to the method, the rare earth lanthanum yield of 70% or above can be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgical material production, and in particular relates to an optimization method for improving the recovery rate of rare earth lanthanum in smelting of a 25kg vacuum induction furnace. Background Art

[0002] With the development of rare earth materials, rare earth in steel has the advantages of grain refinement, microalloying, and improved wear resistance. The addition of rare earth in steel is becoming more and more widely used. However, due to the low melting point and easy oxidation of rare earth alloys, it is very easy to form non-metallic inclusions with oxygen and sulfur in the steel when entering the molten steel, resulting in the instability of rare earth in steel, resulting in low rare earth content and uneven distribution in steel. Therefore, different rare earth addition processes and rare earth recovery rates have become a problem that plagues the development of rare earth steel.

[0003] Patent document CN118086763A (hereinafter referred to as document 1) has provided a control method for improving the rare earth yield of 25kg vacuum induction furnace smelting, and the method can achieve a yield of up to 84% for rare earth cerium in 25kg vacuum induction furnace smelting. However, when the method disclosed in document 1 is used to treat rare earth lanthanum in smelting, the yield of rare earth lanthanum will be reduced. Therefore, there is an urgent need in the art for an optimization method that can improve the yield of rare earth lanthanum in smelting. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides an optimization method for improving the recovery rate of rare earth lanthanum in smelting in a 25kg vacuum induction furnace, which comprises:

[0005] (1) placing a charge in a 25 kg vacuum induction furnace, and placing a lanthanum-iron alloy in an alloy tank of the 25 kg vacuum induction furnace;

[0006] (2) The air in the 25kg vacuum induction furnace was evacuated to below 35Pa, and argon gas was filled to 0.55 standard atmospheric pressure. The furnace was heated at a low power of 30kw for 3 minutes. After the furnace charge turned slightly red, the power was adjusted to 50kw for 2 minutes. Finally, the furnace charge was heated at a high power of 110kw until all the charge was melted. Then, lanthanum-iron alloy was added. After the lanthanum-iron alloy was melted, the power was adjusted to 55kw for 55 seconds to ensure the uniformity of rare earth lanthanum in the molten steel.

[0007] (3) Slowly pour 25 kg of molten steel in the vacuum induction furnace into the ingot mold, and cool the ingot mold under pressure in the furnace for at least 1 hour.

[0008] In some embodiments, the chemical composition of the charge includes, by mass percentage, C 0.10-0.11%, Si0.29-0.32%, Mn 1.69-1.71%, P≤0.015%, Cr 0.40-0.42%, Nb 0.04-0.05%, V 0.06-0.07%, Ti0.011-0.014%, S≤0.005%, Al 0.0022-0.0028%, and the rest is iron and unavoidable impurities.

[0009] In some embodiments, the chemical composition of the charge includes, by mass percentage, C 0.10%, Si 0.32%, Mn 1.69%, P 0.014%, Cr 0.41%, Nb 0.05%, V 0.06%, Ti 0.012%, S 0.003%, Al 0.0025%, and the rest is iron and unavoidable impurities.

[0010] In some embodiments, the chemical composition of the charge includes, by mass percentage, C 0.11%, Si 0.29%, Mn 1.71%, P 0.014%, Cr 0.41%, Nb 0.04%, V 0.06%, Ti 0.011%, S 0.002%, Al 0.0028%, and the rest is iron and unavoidable impurities.

[0011] In some embodiments, the chemical composition of the charge includes, by mass percentage, C 0.11%, Si 0.31%, Mn 1.70%, P 0.014%, Cr 0.41%, Nb 0.05%, V 0.07%, Ti 0.014%, S 0.003%, Al 0.0022%, and the rest is iron and unavoidable impurities.

[0012] In some embodiments, the lanthanum-iron alloy is added in an amount of 0.005-0.02% calculated as lanthanum.

[0013] In some embodiments, the lanthanum yield of the optimized method is greater than 70%.

[0014] In some embodiments, the lanthanum yield of the optimized method is greater than 74%. DETAILED DESCRIPTION

[0015] The object of the present invention is to provide an optimization method for improving the recovery rate of rare earth lanthanum in smelting of 25kg vacuum induction furnace, which specifically comprises:

[0016] (1) placing a charge in a 25 kg vacuum induction furnace, and placing a lanthanum-iron alloy in an alloy tank of the 25 kg vacuum induction furnace;

[0017] (2) The air in the 25kg vacuum induction furnace was evacuated to below 35Pa, and argon gas was filled to 0.55 standard atmospheric pressure. The furnace was heated at a low power of 30kw for 3 minutes. After the furnace charge turned slightly red, the power was adjusted to 50kw for 2 minutes. Finally, the furnace charge was heated at a high power of 110kw until all the charge was melted. Then, lanthanum-iron alloy was added. After the lanthanum-iron alloy was melted, the power was adjusted to 55kw for 55 seconds to ensure the uniformity of rare earth lanthanum in the molten steel.

[0018] (3) Slowly pour 25 kg of molten steel in the vacuum induction furnace into the ingot mold, and cool the ingot mold under pressure in the furnace for at least 1 hour.

[0019] The method provided by the present invention can especially improve the recovery rate of rare earth lanthanum in molten steel in 25kg vacuum induction furnace smelting, which can reach more than 70%, preferably more than 74%.

[0020] The present invention is described in detail below through specific examples. The examples are intended to help understand the present invention but are not intended to limit the present invention.

[0021] Example

[0022] The optimization method for improving the yield of rare earth lanthanum in 25kg vacuum induction furnace smelting provided in the embodiment specifically includes the following operations:

[0023] 1) Calculate the amount of rare earth lanthanum alloy (lanthanum-iron alloy) and the amount of charge added according to the smelting rare earth content;

[0024] 2) Cut the steel material with the composition shown in Table 1 below into standard materials with a length of 410 mm, a thickness of 20 mm and a width of 25 mm and remove the surface iron oxide scale. Weigh the furnace charge and rare earth lanthanum alloy according to the calculated amount in (1);

[0025] 3) Place the weighed charge in a 25kg vacuum induction furnace and place the rare earth alloy in the alloy tank;

[0026] 4) Put ingot mold, add cap bricks, and cover the furnace;

[0027] 5) Turn on the cooling water, turn on the Roots pump to pump the air in the induction furnace to below 35Pa (the vacuum control is shown in Table 2 below), fill with argon to 0.55 standard atmospheric pressure, heat at 30kw for 3 minutes, and when the steel material turns slightly red, adjust the power to 50kw for 2 minutes, and finally heat at 110kw until all the steel material is melted, then add the rare earth alloy, and after the rare earth alloy is melted, adjust the power to 55kw for 55 seconds to ensure the uniformity of the rare earth in the steel;

[0028] 6) Slowly pour the molten steel into the ingot mold;

[0029] 7) Stop heating and cool the ingot mold under pressure in the furnace for 1 hour;

[0030] 8) Lift out the ingot mold and demould;

[0031] 9) Turn off the cooling water, clean the experimental platform, and check the inner wall of the 25kg vacuum induction furnace.

[0032] Comparative Example 1

[0033] Comparative Example 1 is operated in accordance with Example 2, except that the following control is performed in step 5): the cooling water is turned on, the Roots pump is turned on to evacuate the air in the induction furnace to 34 Pa, argon is filled to 0.6 standard atmospheric pressure, 50 kW low power heating is performed for 5 minutes, and then 100 kW high power heating is performed until all the steel materials are melted, and then the rare earth alloy is added, and after the rare earth alloy is melted, the low power heating is adjusted to 50 kW for 1 minute to ensure the uniformity of the rare earth in the steel.

[0034] The yield of rare earth lanthanum in each embodiment and comparative example 1 was tested, and the results are shown in Table 3 below.

[0035] Table 1: Chemical composition and content of steel materials

[0036] Example C / ％ Si / % Mn / % P / ％ Cr％ Nb% V％ Ti% S / ％ Al / ％ 1 0.10 0.32 1.69 0.014 0.41 0.05 0.06 0.012 0.003 0.0025 2 0.11 0.29 1.71 0.014 0.41 0.04 0.06 0.011 0.002 0.0028 3 0.11 0.31 1.70 0.014 0.41 0.05 0.07 0.014 0.003 0.0022

[0037] Table 2: Vacuum furnace process parameters

[0038] Example Vacuum degree / Pa Vacuuming time / min 1 32 5 2 30 5.5 3 25 6

[0039] Table 3: Recovery rate of rare earth lanthanum

[0040] Example Lanthanum addition amount / % Rare earth lanthanum content / % Rare earth lanthanum recovery rate / % 1 0.005 0.0038 76 2 0.02 0.015 75 3 0.015 0.0112 74.6 Comparative Example 1 0.02 0.0121 60.5

[0041] From the results shown in Table 3 above, it can be seen that Examples 1-3 according to the method of the present invention can ultimately achieve a rare earth lanthanum yield of more than 70% (for example, more than 74%), while Comparative Example 1 which does not adopt the method of the present invention can only achieve a rare earth lanthanum yield of 60.5%.

[0042] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An optimization method for improving the yield of rare earth lanthanum in 25kg vacuum induction furnace smelting, characterized in that: The optimization method comprises: (1) placing a charge in a 25 kg vacuum induction furnace, and placing a lanthanum-iron alloy in an alloy tank of the 25 kg vacuum induction furnace; (2) The air in the 25kg vacuum induction furnace was evacuated to below 35Pa, and argon gas was filled to 0.55 standard atmospheric pressure. The furnace was heated at a low power of 30kw for 3 minutes. After the furnace charge turned slightly red, the power was adjusted to 50kw for 2 minutes. Finally, the furnace charge was heated at a high power of 110kw until all the charge was melted. Then, lanthanum-iron alloy was added. After the lanthanum-iron alloy was melted, the power was adjusted to 55kw for 55 seconds to ensure the uniformity of rare earth lanthanum in the molten steel. (3) Slowly pour 25 kg of molten steel in the vacuum induction furnace into the ingot mold, and cool the ingot mold under pressure in the furnace for at least 1 hour.

2. The optimization method according to claim 1, characterized in that: The chemical composition of the charge includes, by mass percentage, C 0.10-0.11%, Si 0.29-0.32%, Mn 1.69-1.71%, P≤0.015%, Cr 0.40-0.42%, Nb0.04-0.05%, V 0.06-0.07%, Ti 0.011-0.014%, S≤0.005%, Al 0.0022-0.0028%, and the rest is iron and unavoidable impurities.

3. The optimization method according to claim 1 or 2, characterized in that: The chemical composition of the charge includes, by mass percentage, C 0.10%, Si 0.32%, Mn 1.69%, P 0.014%, Cr 0.41%, Nb 0.05%, V 0.06%, Ti 0.012%, S 0.003%, Al 0.0025%, and the rest is iron and unavoidable impurities.

4. The optimization method according to claim 1 or 2, characterized in that: The chemical composition of the charge includes, by mass percentage, C 0.11%, Si 0.29%, Mn 1.71%, P 0.014%, Cr 0.41%, Nb 0.04%, V 0.06%, Ti 0.011%, S 0.002%, Al 0.0028%, and the rest is iron and unavoidable impurities.

5. The optimization method according to claim 1 or 2, characterized in that: The chemical composition of the charge includes, by mass percentage, C 0.11%, Si 0.31%, Mn 1.70%, P 0.014%, Cr 0.41%, Nb 0.05%, V 0.07%, Ti 0.014%, S 0.003%, Al 0.0022%, and the rest is iron and unavoidable impurities.

6. The optimization method according to any one of claims 1 to 5, characterized in that: The amount of lanthanum-iron alloy added is 0.005-0.02% calculated as lanthanum.

7. The optimization method according to any one of claims 1 to 6, characterized in that: The lanthanum recovery rate of the optimized method is above 70%.

8. The optimization method according to claim 7, characterized in that: The lanthanum recovery rate of the optimized method is above 74%.