Method for precipitating rare earth by oxalic acid

Abstract

The invention belongs to the field of hydrometallurgy, and discloses a method for precipitating rare earth by oxalic acid, which comprises the following steps: adding a masking agent A into a rare earth solution, adjusting the pH value, adding a masking agent B and a masking agent C after reaction, carrying out solid-liquid separation after reaction again, roasting to obtain solid particles, and cooling to obtain high-purity rare earth oxide. By adding the masking agent, the content of impurity elements in the prepared rare earth oxide is reduced, the direct recovery rate of rare earth elements is increased, and the purity of the product is improved; by optimizing the preparation process, the rare earth oxide is fine in particle size and narrow in particle distribution.

Description

Technical Field

[0001] The invention belongs to the field of hydrometallurgy, relates to the extraction of rare earth elements, and in particular to a method for precipitating rare earth with oxalic acid. Background Art

[0002] Rare earths are called the "vitamins" of modern industry and the "treasure trove of new materials in the 21st century". Rare earth products are diverse and widely used. Rare earth elements in ores are generally separated in the form of oxides. Ammonium bicarbonate precipitation and oxalic acid precipitation are usually used to prepare rare earth oxides. Oxalic acid precipitation can effectively separate rare earth elements, and the rare earth oxides produced have the advantages of fine particle size, high purity, and coarse grains.

[0003] In the process of oxalic acid precipitation of rare earth elements, a small amount of Fe, Ca, Zr, and Ti in the rare earth solution will co-precipitate with the oxalic acid and enter the product, thereby affecting the purity of the rare earth oxides. Summary of the invention

[0004] In view of the defects and shortcomings of the prior art, the present invention provides a method for precipitating rare earth with oxalic acid. On the one hand, the purity of the obtained rare earth oxide is improved; on the other hand, rare earth oxide with fine particle size and narrow particle distribution is obtained by optimizing the process.

[0005] The present invention provides a method for precipitating rare earth with oxalic acid, comprising the following steps: Step 1, adding masking agent A to a rare earth solution to react to obtain solution A, and then adjusting the pH value of solution A to 0.5-4 to obtain solution B; Step 2, adding masking agent B and masking agent C to solution B, reacting to obtain solution C; Step 3, adding oxalic acid solution to solution C, reacting to obtain slurry; Step 4, the slurry is subjected to solid-liquid separation to obtain a solid phase, and the solid phase is calcined to obtain high-purity rare earth oxides.

[0006] Preferably, the masking agent A is any one or more of H2O2 (hydrogen peroxide), ammonium persulfate, HClO (hypochlorous acid), HClO3 (chloric acid), HClO4 (perchloric acid), and nitric acid.

[0007] Preferably, the masking agent B is tartaric acid.

[0008] Preferably, the masking agent C is any one or more of EDTA (ethylenediaminetetraacetic acid), NTA (nitrilotriacetic acid), HEDTA (hydroxyethylethylenediaminetetraacetic acid), DTPA (diethylenetriaminepentaacetic acid), DCTA (1,2-cyclohexanediaminetetraacetic acid), and lactic acid.

[0009] Preferably, the pH adjuster is any one or more of sodium hydroxide, ammonia water and sodium carbonate.

[0010] Preferably, the molar ratio of the masking agent A added to the rare earth solution to the ferrous ions in the rare earth solution is 1:1-2.

[0011] Preferably, the molar ratio of the masking agent B added to the solution B to the total molar amount of calcium ions and zirconium ions in the rare earth solution is 1:1-2.

[0012] Preferably, the molar ratio of the masking agent C added to the solution B to the titanium ions in the rare earth solution is 1:1-2.

[0013] Preferably, the molar ratio of the rare earth element in the solution C to the oxalate in the oxalic acid solution added to the solution C is 1:1-2.

[0014] In step 3, when the oxalic acid solution is added, an organic polymer surface dispersant is also added.

[0015] Preferably, the organic polymer surface dispersant is any one or more of CTAB (cetyltrimethylammonium bromide), PEG (polyethylene glycol), CPAM (polyacrylamide), and ethanol.

[0016] Preferably, the concentration of the organic polymer surface dispersant in the slurry is 0.1 wt % to 20 wt %.

[0017] Preferably, in step 4, the calcination temperature is 750-1000° C. and the calcination time is 0.5-5 h.

[0018] Compared with the prior art, the above one or more technical solutions of the present invention have at least one of the following beneficial effects: (1) The present invention reduces the content of impurity elements in the prepared rare earth oxide by adding a masking agent, thereby increasing the direct yield of rare earth elements and improving the purity of the product.

[0019] (2) Rare earth oxides with fine particle size and narrow particle distribution are produced by optimizing the preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention provides a process flow chart of a method for precipitating rare earth with oxalic acid. DETAILED DESCRIPTION

[0021] The present invention provides the following specific technical solutions.

[0022] A method for precipitating rare earth with oxalic acid, comprising the following steps: Step 1, adding masking agent A to the rare earth solution to react, to obtain solution A, and then adding a pH adjuster to the solution A to adjust the pH value of the solution A to 0.5-4, to obtain solution B; Step 2, adding masking agent B and masking agent C to solution B, reacting to obtain solution C; Step 3, adding oxalic acid solution and organic polymer surface dispersant to solution C, reacting to obtain slurry; Step 4, solid-liquid separation slurry, solid-liquid separation slurry, roasting the obtained solid particles, and cooling them to obtain high-purity rare earth oxides.

[0023] Masking agent A makes Fe 2+ , Fe 3+ ions are not precipitated by oxalic acid, and masking agent B makes Ca 2+ 、Zr 4+ Not precipitated by oxalic acid, masking agent C makes Ti 4+ It is not precipitated by oxalic acid, reducing the possibility of co-precipitation of impurity elements and rare earth elements; by adding a masking agent, the problem of impurity co-precipitation in the traditional oxalic acid precipitation method is effectively solved, the direct yield of rare earth elements is increased, and the purity of the product is improved. And by optimizing the preparation process, rare earth oxides with fine particle size and narrow particle distribution are obtained.

[0024] Preferably, the masking agent A is any one or more of H2O2 (hydrogen peroxide), ammonium persulfate, HClO (hypochlorous acid), HClO3 (chloric acid), HClO4 (perchloric acid), and nitric acid.

[0025] Preferably, the masking agent B is tartaric acid.

[0026] Preferably, the masking agent C is any one or more of EDTA (ethylenediaminetetraacetic acid), NTA (nitrilotriacetic acid), HEDTA (hydroxyethylethylenediaminetetraacetic acid), DTPA (diethylenetriaminepentaacetic acid), DCTA (1,2-cyclohexanediaminetetraacetic acid), and lactic acid.

[0027] Preferably, the pH adjuster is any one or more of sodium hydroxide, ammonia water and sodium carbonate.

[0028] Preferably, the molar ratio of the masking agent A added to the rare earth solution to the ferrous ions in the rare earth solution is 1:1-2.

[0029] Preferably, the molar ratio of the masking agent B added to the solution B to the total molar amount of calcium ions and zirconium ions in the rare earth solution is 1:1-2.

[0030] Preferably, the molar ratio of the masking agent C added to the solution B to the titanium ions in the rare earth solution is 1:1-2.

[0031] Preferably, the molar ratio of the rare earth element in the solution C to the oxalate in the oxalic acid solution added to the solution C is 1:1-2.

[0032] Adding excess masking agent A, masking agent B, and masking agent C can improve the masking effect and further reduce the possibility of co-precipitation of impurity elements and rare earth elements.

[0033] In step 3, when the oxalic acid solution is added, an organic polymer surface dispersant is also added.

[0034] Preferably, the organic polymer surface dispersant is any one or more of CTAB (cetyltrimethylammonium bromide), PEG (polyethylene glycol), CPAM (polyacrylamide), and ethanol.

[0035] By adding an organic polymer surface dispersant, the problem of coarse and uneven particle size of rare earth oxide particles prepared by traditional oxalic acid precipitation is effectively solved. In addition, masking agent A, masking agent B, masking agent C and organic polymer surface dispersant will not introduce other impurity elements, which is conducive to improving the purity of the product.

[0036] Preferably, the concentration of the organic polymer surface dispersant in the slurry is 0.1 wt % to 20 wt %.

[0037] Preferably, in step 4, the calcination temperature is 750-1000° C. and the calcination time is 0.5-5 h.

[0038] In order to make the technical problems, technical solutions and technical advantages to be solved by the present invention more clear, they will be described in detail below with reference to specific examples, but the protection scope of the present invention is not limited to the following specific embodiments.

[0039] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0040] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0041] The rare earth solutions used in the following examples 1 and comparative examples 1-2 are all scandium chloride solutions. 3+ The concentration of Fe is 10.14 g / L 2+ The concentration of Zr is 0.14g / L 4+ The concentration is 0.0030g / L, Ca 2+ The concentration is 0.0076g / L, Ti 4+ The concentration is 0.028g / L.

[0042] The rare earth solution used in Example 2 is a scandium nitrate solution, wherein the Sc 3+ The concentration of Fe is 10.91 g / L 2+ The concentration of Zr is 0.12g / L 4+ The concentration is 0.0095g / L, Ca 2+ The concentration is 0.0083g / L, Ti 4+ The concentration is 0.035g / L.

[0043] The rare earth solution used in Example 3 is a cerium chloride solution, wherein Ce 3+ The concentration of Fe is 12.66 g / L. 2+ The concentration of Zr is 0.18g / L 4+ The concentration of Ca is 0.0083 g / L. 2+ The concentration of Ti is 0.0046g / L 4+ The concentration is 0.035g / L.

[0044] The rare earth solution used in Example 4 is a lanthanum sulfate solution. 3+ The concentration of Fe is 2.17 g / L 2+ The concentration is 0.095g / L, Zr 4+ The concentration is 0.0078g / L, Ca 2+ The concentration of Ti is 0.0038g / L 4+ The concentration is 0.019g / L.

[0045] Embodiment 1: A method for precipitating rare earth with oxalic acid, comprising the following steps: Step 1, adding hydrogen peroxide to the scandium chloride solution, reacting to obtain solution A, then adding ammonia water to the solution A to adjust the pH value to 2, to obtain solution B; wherein the molar ratio of the added hydrogen peroxide to the ferrous ions in the scandium chloride solution is 1.5:1.

[0046] Step 2, heating solution B to 80°C, then adding tartaric acid and EDTA to solution B, stirring the reaction for 30 minutes, to obtain solution C; wherein the molar ratio of the added tartaric acid to the total molar amount of calcium ions and zirconium ions in solution B is 2:1, and the molar ratio of the added EDTA to the titanium ions in solution B is 2:1.

[0047] Step 3, adding oxalic acid solution and CTAB to solution C to react to obtain slurry; the molar ratio of oxalate in the oxalic acid solution added to solution C to scandium ions in solution C is 1.2:1, and the concentration of CTAB in the slurry is 0.1wt% unit.

[0048] Step 4, solid-liquid separation of the slurry, and calcination of the obtained solid particles at 850° C. for 1 hour to obtain high-purity scandium oxide.

[0049] Comparative Example 1: A method for precipitating rare earth with oxalic acid, comprising the following steps: Step 1, adding ammonia water to the scandium chloride solution to adjust the pH value to 2, heating the scandium chloride solution to 80° C., then adding tartaric acid and EDTA to the scandium chloride solution, stirring and reacting for 30 minutes to obtain solution A; wherein the molar ratio of the added tartaric acid to the total molar amount of calcium ions and zirconium ions in solution A is 2:1, and the molar ratio of the added EDTA to the titanium ions in solution A is 2:1.

[0050] Step 2, adding hydrogen peroxide to solution A to obtain solution B, wherein the molar ratio of the added hydrogen peroxide to the ferrous ions in the scandium chloride solution is 1.5:1.

[0051] Step 3, adding oxalic acid solution and CTAB to solution B to react to obtain slurry; the molar ratio of oxalate in the oxalic acid solution added to solution B to scandium ions in solution B is 1.2:1, and the concentration of CTAB in the slurry is 0.1wt%.

[0052] Step 4, solid-liquid separation of the slurry, and calcination of the obtained solid particles at 850° C. for 1 hour to obtain high-purity scandium oxide.

[0053] Comparative Example 2: A method for precipitating rare earth with oxalic acid, comprising the following steps: Step 1, adding sodium hydroxide to the scandium chloride solution to adjust the pH value to 2 to obtain solution A.

[0054] Step 2, adding oxalic acid solution and CTAB to solution A, wherein the concentration of CTAB in the slurry is 0.1wt%. Reaction to obtain slurry; the molar ratio of oxalate in the oxalic acid solution added to solution A to scandium ions in solution A is 1.2:1.

[0055] Step 4, solid-liquid separation of the slurry, and calcination of the obtained solid particles at 850° C. for 1 hour to obtain high-purity scandium oxide.

[0056] Embodiment 2: A method for precipitating rare earth with oxalic acid, comprising the following steps: Step 1, adding ammonium persulfate to a scandium nitrate solution, reacting to obtain solution A, then adding sodium carbonate to solution A to adjust the pH value to 1.5 to obtain solution B; wherein the molar ratio of the added ammonium persulfate to the ferrous ions in the scandium chloride solution is 1.2:1.

[0057] Step 2, heating solution B to 80°C, then adding tartaric acid and NTA to solution B, stirring the reaction for 30 minutes, to obtain solution C; wherein the molar ratio of the added tartaric acid to the total molar amount of calcium ions and zirconium ions in solution B is 1:1, and the molar ratio of the added EDTA to the titanium ions in solution B is 1:1.

[0058] Step 3, adding oxalic acid solution and PEG to solution C to react to obtain a slurry; the molar ratio of oxalate in the oxalic acid solution added to solution C to the scandium ion in solution C is 1.3:1, and the concentration of PEG in the slurry is 10wt%.

[0059] Step 4, solid-liquid separation of the slurry, and calcination of the obtained solid particles at 750° C. for 2 h to obtain high-purity scandium oxide.

[0060] Embodiment 3: A method for precipitating rare earth with oxalic acid, comprising the following steps: Step 1, adding perchloric acid to a cerium chloride solution, reacting to obtain solution A, then adding sodium hydroxide to solution A to adjust the pH value to 1.0 to obtain solution B; wherein the molar ratio of the added perchloric acid to the ferrous ions in the scandium chloride solution is 2:1.

[0061] Step 2, heating solution B to 80°C, then adding tartaric acid and HEDTA to solution B, stirring the reaction for 30 minutes, to obtain solution C; wherein the molar ratio of the added tartaric acid to the total molar amount of calcium ions and zirconium ions in solution B is 1.5:1, and the molar ratio of the added EDTA to the titanium ions in solution B is 1.5:1.

[0062] Step 3, adding oxalic acid solution and CPAM to solution C to react to obtain slurry; the molar ratio of oxalate ions in the oxalic acid solution added to solution C to cerium ions in solution C is 1.5:1, and the concentration of CPAM in the slurry is 0.5wt%.

[0063] Step 4, solid-liquid separation of the slurry, and calcining the obtained solid particles at 800° C. for 2 h to obtain high-purity scandium oxide.

[0064] Embodiment 4: A method for precipitating rare earth with oxalic acid, comprising the following steps: Step 1, adding hypochlorous acid to a lanthanum sulfate solution, reacting to obtain solution A, then adding ammonia water to solution A to adjust the pH value to 2, to obtain solution B; wherein the molar ratio of the added hypochlorous acid to the ferrous ions in the lanthanum sulfate solution is 2:1.

[0065] Step 2, heating and stirring solution B, then adding tartaric acid and EDTA to solution B, reacting to obtain solution C; wherein the molar ratio of the added tartaric acid to the total molar amount of calcium ions and zirconium ions in solution B is 2:1, and the molar ratio of the added EDTA to the titanium ions in solution B is 1:1.

[0066] Step 3, adding oxalic acid solution and CPAM to solution C to react to obtain slurry; the molar ratio of oxalate ions in the oxalic acid solution added to solution C to lanthanum ions in solution C is 2:1, and the concentration of CPAM in the slurry is 0.1wt%.

[0067] Step 4, solid-liquid separation of the slurry, and calcination of the obtained solid particles at 850° C. for 1 hour to obtain high-purity scandium oxide.

[0068] The components of the rare earth oxides obtained in Examples 1 to 4 and Comparative Examples 1 to 2 were tested, and the test results are shown in Table 1.

[0069] Table 1 Composition test data of rare earth oxides prepared in Examples 1 to 4 and Comparative Examples 1 to 2 As can be seen from Table 1, the preparation method provided by the present invention has a higher yield of rare earth elements, a higher purity of the prepared rare earth oxides, a smaller particle size and a narrower particle size distribution.

[0070] By comparing the composition detection data of the rare earth oxides obtained in Example 1 and Comparative Example 1, it can be seen that if the process flow is adjusted, masking agent B and masking agent C are added first, and then masking agent A is added, the content of impurity iron in the obtained rare earth oxide is slightly increased, and the particle size of the rare earth oxide is larger, and the degree of difference in particle size is also increased.

[0071] By comparing Example 1 with Comparative Example 2, it can be seen that masking agent A, masking agent B and masking agent C can improve the purity of rare earth oxides, and the particle size and particle size difference of rare earth oxides are reduced.

[0072] The embodiments described above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the technical scope of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for precipitating rare earth with oxalic acid, characterized in that: The steps include: Step 1, adding masking agent A to a rare earth solution to react to obtain solution A, and then adjusting the pH value of solution A to 0.5-4 to obtain solution B; Step 2, adding masking agent B and masking agent C to solution B, reacting to obtain solution C; Step 3, adding oxalic acid solution to solution C, reacting to obtain slurry; Step 4, the slurry is subjected to solid-liquid separation to obtain a solid phase, and the solid phase is calcined to obtain high-purity rare earth oxides.

2. The method for preparing rare earth precipitated with oxalic acid according to claim 1, characterized in that: Masking agent A is any one or more of H2O2, ammonium persulfate, HClO, HClO3, HClO4, and nitric acid.

3. The method for preparing rare earth precipitated by oxalic acid according to claim 1, characterized in that: Masking agent B is tartaric acid.

4. The method for preparing rare earth precipitated by oxalic acid according to claim 1, characterized in that: The masking agent C is any one or more of EDTA (ethylenediaminetetraacetic acid), NTA (nitrilotriacetic acid), HEDTA (hydroxyethylethylenediaminetetraacetic acid), DTPA (diethylenetriaminepentaacetic acid), DCTA (1,2-cyclohexanediaminetetraacetic acid), and lactic acid.

5. The method for preparing rare earth precipitated by oxalic acid according to claim 1, characterized in that: The molar ratio of the masking agent A added to the rare earth solution to the ferrous ions in the rare earth solution is 1:1-2.

6. The method for preparing rare earth precipitated by oxalic acid according to claim 1, characterized in that: The molar ratio of the masking agent B added to the solution B to the total molar amount of calcium ions and zirconium ions in the rare earth solution is 1:1-2.

7. The method for preparing rare earth precipitated by oxalic acid according to claim 1, characterized in that: The molar ratio of the masking agent C added to the solution B to the titanium ions in the rare earth solution is 1:1-2; The molar ratio of the rare earth element in the solution C to the oxalate in the oxalic acid solution added to the solution C is 1:1-2.

8. The method for preparing rare earth precipitated by oxalic acid according to claim 1, characterized in that: In step 3, when the oxalic acid solution is added, an organic polymer surface dispersant is also added.

9. The method for preparing rare earth precipitated by oxalic acid according to claim 8, characterized in that: The organic polymer surface dispersant is any one or more of CTAB, PEG, CPAM and ethanol; The concentration of the organic polymer surface dispersant in the slurry is 0.1 wt % to 20 wt %.

10. The method for preparing rare earth precipitated by oxalic acid according to claim 1, characterized in that: In step 4, the calcination temperature is 750-1000° C. and the calcination time is 0.5-5 h.

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