Method for detecting content of lanthanum oxide in lanthanum nitrate

Abstract

The invention discloses a method for detecting the content of lanthanum oxide in lanthanum nitrate. The detection method comprises the following steps: recording the constant weight mass m0 of the ceramic container at room temperature; weighing a lanthanum nitrate sample with the mass of m2, putting the lanthanum nitrate sample into a ceramic container, placing the ceramic container in a furnace door area of a high-temperature furnace with the temperature of 126 DEG C, transferring to a temperature measuring area of the high-temperature furnace with the temperature of 800 DEG C after nitrogen dioxide in the lanthanum nitrate sample is completely volatilized, closing the furnace door, and firing at the temperature of 800 DEG C until lanthanum nitrate is completely decomposed and converted into lanthanum oxide, taking out, cooling and recording the total mass m2 of the ceramic container; lanthanum oxide is obtained through m0, m1 and m2. The method disclosed by the invention is simple and convenient to operate, wide in measurement range (up to 30.00-75.00%), high in accuracy and good in reproducibility.

Description

Technical Field

[0001] The present invention relates to a method for detecting the content of rare earth oxides in rare earth nitrate, in particular to a method for detecting the content of lanthanum oxide in lanthanum nitrate. Background Art

[0002] Currently, two main methods are used to determine the total amount of rare earth elements in rare earth metals and their compounds: the oxalate gravimetric method and the EDTA titration method. According to the national standard GB / T 14635-2020, the oxalate gravimetric method is applicable to the determination of the total amount of rare earth elements in both single and mixed rare earth metals and their compounds, with a determination range of 30% to 70%. While this method has a wide range of applications, it is complex, involving multiple steps such as precipitation, filtration, and calcination. This is not only time-consuming but also prone to human error, affecting the accuracy and reproducibility of the results. The EDTA titration method is suitable for single rare earth metals and mixed rare earth metals primarily composed of heavy rare earths. However, due to the chemical properties of rare earth nitrates and the numerous interfering factors, this method cannot be directly applied to the determination of rare earth nitrates. Therefore, in practical testing, the determination of rare earth nitrates, such as lanthanum nitrate, relies solely on the oxalate gravimetric method, which is complex and inefficient, making it difficult to meet the requirements of modern industrial production for rapid and accurate testing.

[0003] Therefore, it is urgent to establish a new method suitable for the determination of lanthanum oxide content in lanthanum nitrate, which has the characteristics of simple operation, wide measurement range such as 30.00% to 75.00%, high accuracy and good reproducibility, so as to fill the gap in existing detection technology and improve the quality control level of the rare earth industry. Summary of the Invention

[0004] In view of the defects of the prior art, the purpose of the present invention is to provide a new method for detecting the lanthanum oxide content in lanthanum nitrate, which is simple to operate, has a wide measurement range (can reach 30.00%-75.00%), and has high accuracy and good reproducibility.

[0005] The technical solutions of the present invention are as follows:

[0006] A method for detecting the content of lanthanum oxide in lanthanum nitrate, comprising:

[0007] (1) Heat the cleaned ceramic container to 750-850°C and keep it warm for 20-40 minutes, then cool it to room temperature and record its constant weight m0 at room temperature;

[0008] (2) Weighing a lanthanum nitrate sample with a mass of m1 into the ceramic container, placing it in the low-temperature area of ​​a high-temperature furnace at a temperature of 126°C until the nitrogen dioxide therein is completely volatilized, and then transferring it to the high-temperature area of ​​a high-temperature furnace at a temperature of 800°C and closing the furnace door;

[0009] (3) calcining at 800°C until the lanthanum nitrate sample is completely decomposed and converted into lanthanum oxide, then removing and cooling, and recording the total mass m2 of the ceramic container after calcination;

[0010] The lanthanum oxide content ω(La2O3) was obtained by the following calculation model:

[0011]

[0012] According to some preferred embodiments of the present invention, the ceramic container is a ceramic crucible.

[0013] According to some preferred embodiments of the present invention, the low-temperature area of ​​the high-temperature furnace is near the door of the high-temperature furnace.

[0014] According to some preferred embodiments of the present invention, the high-temperature area is a temperature measurement area of ​​a high-temperature furnace.

[0015] According to some preferred embodiments of the present invention, the heat preservation and burning time is 2.0-2.5 hours.

[0016] According to some preferred embodiments of the present invention, the lanthanum oxide content is 30.00%-75.00%.

[0017] The present invention is based on the following principles:

[0018] When lanthanum nitrate is heated to 126°C (boiling point), it begins to decompose, first forming a basic salt and then forming an oxide. When it is heated to 800°C, it can be completely decomposed into lanthanum oxide. The chemical reaction equation is as follows:

[0019]

[0020] The process and principle of the traditional oxalate weight method are as follows:

[0021] In acidic or weakly acidic media, lanthanum ions (La 3+ ) and oxalate ion (C2O4 3 -) reaction to generate a white lanthanum oxalate precipitate as follows:

[0022] 2La 3+ +3C2O4 3- →La2(C2O4)3↓;

[0023] The cleaned lanthanum oxalate precipitate is burned at high temperature (usually >800℃). Lanthanum oxalate decomposes to form lanthanum oxide and releases carbon dioxide and water vapor as follows:

[0024] La2(C2O4)3+2O2→La2O3+6CO2↑(in air)

[0025] La2(C2O4)3→La2O3+3CO↑+3CO2↑(under inert atmosphere or high temperature and oxygen-deficient conditions);

[0026] The obtained lanthanum oxide is kept at 70-80° C. for 1-2 hours (or overnight) and stirred from time to time during the aging period to make the precipitate particles coarse and pure, which is convenient for filtration and washing. The lanthanum oxide precipitate after washing, filtration and drying is then weighed.

[0027] The present invention has the following beneficial effects:

[0028] (1) Compared with the traditional oxalate gravimetric method, the present invention eliminates the tedious precipitation, filtration and washing steps, simplifies the operation process, and significantly improves the detection efficiency;

[0029] (2) The present invention can measure the lanthanum oxide content range of 30.00%-75.00%, and has a wide range of applications;

[0030] (3) The present invention effectively avoids the influence of nitrogen dioxide residue on the measurement results through the gradient heating process, thereby ensuring the accuracy of the test results;

[0031] (4) The present invention has stable control and good repeatability. At the same time, it can be completed by using only conventional high-temperature furnaces and weighing equipment, which reduces the detection cost and is convenient for promotion and application in industrial production and laboratories. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The present invention is a flow chart of the method for detecting the content of lanthanum oxide in lanthanum nitrate in Example 1. DETAILED DESCRIPTION

[0033] The technical solutions of the present invention will be further described below in conjunction with the embodiments of the present invention. The embodiments described below are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0034] Example 1

[0035] Refer to the attached Figure 1 , the lanthanum oxide content in lanthanum nitrate is determined by the following process:

[0036] (1) Place the cleaned ceramic crucible in a high-temperature furnace, heat it to 800°C and keep it warm for 30 minutes; take it out and place it in a constant temperature dryer to cool to room temperature. After about 1 hour, weigh it and record its mass m0;

[0037] (2) After weighing and taring the crucible, accurately weigh 10.0000 g of lanthanum nitrate sample and record its mass as m1;

[0038] (3) The temperature of the high-temperature furnace is set to 800°C. Before placing the lanthanum nitrate sample, the furnace temperature is raised to 126°C. The crucible containing the lanthanum nitrate sample is then placed in the area of ​​the high-temperature furnace door to allow the nitrogen dioxide (NO2) therein to fully volatilize. After the nitrogen dioxide has completely evaporated, the crucible is transferred to the temperature measurement area of ​​the high-temperature furnace and the furnace door is closed.

[0039] (4) After the high-temperature furnace is heated to 800°C, it is kept at this temperature for 2 hours for calcination to completely decompose the lanthanum nitrate sample and convert it into lanthanum oxide (La2O3);

[0040] (5) After the burning is completed, turn off the power of the high-temperature furnace, take out the crucible and place it in a constant temperature dryer to cool to room temperature. After about 1 hour, take it out and weigh it, and record its mass m2;

[0041] (6) The lanthanum oxide content was obtained by the following calculation formula:

[0042]

[0043] According to the above process, this embodiment carried out multiple tests on 5 samples, and the test results are shown in Table 1 below:

[0044] Table 1 Example test results

[0045]

[0046] The test results are consistent with the actual lanthanum oxide content of the samples used, and the test results are stable and have no significant deviation, proving the feasibility of this method.

[0047] It should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the technical solutions of the present invention. Any modifications to the technical solutions described in the aforementioned embodiments, or equivalent replacements of technical features made by persons of ordinary skill in the art that fall within the spirit and principles of the present invention, shall be included within the scope of protection of the present invention.

Claims

1. A method for detecting the content of lanthanum oxide in lanthanum nitrate, characterized in that: It includes: (1) Heat the cleaned ceramic container to 750-850°C and keep it warm for 20-40 minutes, then cool it to room temperature and record its constant weight m0 at room temperature; (2) Weighing a lanthanum nitrate sample with a mass of m1 into the ceramic container, placing it in the low-temperature area of ​​a high-temperature furnace at a temperature of 126°C until the nitrogen dioxide therein is completely volatilized, and then transferring it to the high-temperature area of ​​a high-temperature furnace at a temperature of 800°C and closing the furnace door; (3) calcining at 800°C until the lanthanum nitrate sample is completely decomposed and converted into lanthanum oxide, then removing and cooling, and recording the total mass m2 of the ceramic container after calcination; (4) The lanthanum oxide content ω(La2O3) is obtained by the following calculation model:

2. The detection method according to claim 1, wherein The ceramic container is a ceramic crucible.

3. The detection method according to claim 1, wherein The low temperature area of ​​the high temperature furnace is near the door of the high temperature furnace.

4. The detection method according to claim 1, wherein The high temperature area is a high temperature furnace temperature measurement area.

5. The detection method according to claim 1, wherein The heat preservation and burning time is 2.0-2.5h.

6. The detection method according to claim 1, characterized in that The lanthanum oxide content is 30.00%-75.00%.

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