Method for removing impurities from rare earth solution
By using alkali conversion to slag instead of sodium carbonate in the rare earth smelting and separation process, and combining the use of sodium carbonate and flocculant, the problems of high cost and complex steps in the existing process are solved, and efficient and economical rare earth solution removal effect is achieved.
Patent Information
- Application Number
- CN202411737122.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-29
- Publication Date
- 2025-03-04
AI Technical Summary
In the existing rare earth smelting and separation processes, the high cost and cumbersome process steps of sodium carbonate lead to high energy consumption and complex processes, and the problem of iron-thorium slag treatment affects the yield and cost of rare earths.
Alkaline conversion slag is used instead of sodium carbonate in the traditional process, iron impurities are removed through the reaction of the mixed liquid and the slurry, sodium carbonate and calcium carbonate are added, and fluorine and aluminum impurities are removed using flocculant to simplify the process flow and recover the slag material.
It effectively reduces raw material costs and energy consumption, simplifies the removal steps, improves the PN yield of rare earths, reduces emissions and resource consumption, and has good economic benefits and production application value.
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Figure BDA0005161750740000112
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of rare earth impurity removal, and in particular to a method for removing impurities from a rare earth solution. Background Art
[0002] In the rare earth production process, since the original ore contains aluminum, iron and fluorine, the optimal solution and leaching solution obtained after multiple processes contain a large amount of these impurities, which need to be removed before concentration to avoid affecting subsequent extraction.
[0003] At present, the rare earth smelting and separation industry generally uses sodium carbonate for impurity removal. First, sodium carbonate is used to consume acid and increase pH to precipitate trivalent iron at high temperature to form thorium slag, and then a small amount of sodium carbonate is added at high temperature to precipitate F. The advantage of this scheme is that the impurity removal effect is good and can meet the qualified standard, but in this process, the cost of sodium carbonate raw materials is relatively high, and the process steps are relatively complicated. The iron and aluminum removal and fluorine removal steps are carried out separately. The connection process takes a long time, the heat loss is serious, and the energy consumption remains high. In addition, the treatment of thorium slag is also a problem. The thorium slag containing 20-30% wet-basis REO can only be increased by alkali conversion to increase the export of aluminum. A large amount of thorium slag idling seriously affects the workload of other subsequent positions such as water washing, and also has a significant impact on the PN of the cerium-rich product, which seriously restricts the improvement of PN yield (praseodymium and neodymium yield), which is not conducive to reducing the cost of rare earth smelting and separation. Summary of the invention
[0004] The purpose of the present application is to provide a method for removing impurities from a rare earth solution, which can effectively reduce raw material costs and energy consumption, thereby comprehensively reducing the cost of the impurity removal process, and can effectively improve its PN yield; it optimizes the process flow, simplifies the impurity removal steps, reduces energy consumption, and also improves the convenience of process operation, which is more conducive to actual production applications.
[0005] The technical solution of this application is as follows:
[0006] The present invention provides a method for removing impurities from a rare earth solution, which comprises the following steps:
[0007] Mixed solution preparation: the preferred solution and preferred leaching solution obtained in the rare earth production process are pumped into a reaction container to form a mixed solution;
[0008] Preparation of slag slurry: Take the alkali-converted slag obtained in the rare earth production process and add water to prepare slag slurry for use;
[0009] Acid consumption for iron removal: adding slag slurry to the mixed solution to reduce the acidity of the system, then heating up to react and remove iron impurities to obtain the first material;
[0010] Fluorine and aluminum removal: Sodium carbonate and calcium carbonate are added to the first material, stirred to react, and the second material is obtained. A flocculant is then added to the second material for clarification to obtain a decontamination liquid and slag material. The decontamination liquid is used for subsequent processes such as concentration in rare earth production.
[0011] Slag recovery: The slag is subjected to a dissolving treatment to obtain a dissolving slag and a decontamination solution. The dissolving slag is sent to a cerium-rich slag warehouse, and the decontamination solution is recovered and reused.
[0012] Furthermore, in some embodiments of the present application, in the above-mentioned mixed solution preparation step, the volume ratio of the preferred solution to the preferred immersion solution used is 1:1.
[0013] Furthermore, in some embodiments of the present application, in the above-mentioned slurry preparation step, the mass ratio of the alkali-converted slag to water used is 1:1.
[0014] Furthermore, in some embodiments of the present application, in the above-mentioned acid-consuming iron removal step, slag slurry is added to the mixed solution to adjust the pH value of the system to 1.5-2, and then the temperature is raised to react.
[0015] Furthermore, in some embodiments of the present application, in the above-mentioned acid-consuming iron removal step, the temperature is raised to above 80° C. for reaction.
[0016] Furthermore, in some embodiments of the present application, in the method steps, the mass ratio of the water-washed qualified alkali-converted slag (dry slag), sodium carbonate and calcium carbonate used is 20:1:2.
[0017] Furthermore, in some embodiments of the present application, in the above-mentioned fluorine removal and aluminum removal steps, the flocculant used is an acidic flocculant.
[0018] Furthermore, in some embodiments of the present application, in the above-mentioned slag recovery step, the slag is subjected to a solution treatment, comprising the following steps:
[0019] Add water to the slag and stir to mix, then add hydrochloric acid to react, add flocculant to precipitate after the reaction to obtain a decontaminated superior solution and superior slag, the decontaminated superior solution is sent to a superior solution storage tank, and the superior slag is sent to a cerium-rich slag warehouse after washing and filtration.
[0020] Furthermore, in some embodiments of the present application, in the above-mentioned slag recovery step, the slag is subjected to a dissolution treatment at room temperature.
[0021] Compared with the prior art, the embodiments of the present application have at least the following advantages or beneficial effects:
[0022] In view of the above aspects, the embodiment of the present application provides a method for removing impurities from a rare earth solution, which first prepares an optimal solution, an optimal leaching solution, and an alkali-transformed slag that has been washed and qualified during the rare earth production process, and then mixes the optimal solution and the optimal leaching solution to obtain a mixed solution, and at the same time, adds water to the alkali-transformed slag to obtain a slurry, and then adds the slurry to the mixed solution for reaction, and uses the alkali-transformed slag obtained in the rare earth process to replace the sodium carbonate in the traditional process to consume the acid in the material, and then heats up for further reaction to remove the iron impurities in the material to obtain a first material. Sodium carbonate and calcium carbonate are then added to the first material for reaction, and the fluorine impurities and aluminum impurities in the material are separated by adding a flocculant to clarify, thereby obtaining an impurity-removing liquid, which can be put into subsequent rare earth product processes (such as concentration, etc.) for production. The slag obtained by clarification and separation is recycled, and the slag is subjected to optimal dissolution treatment to obtain an impurity-removing optimal solution and an optimal dissolving slag, wherein the optimal dissolving slag is a cerium-rich slag, which is sent to a cerium-rich slag warehouse for storage, and the impurity-removing optimal solution can be recycled and reused (such as bottom water for the optimal dissolving process of rare earth production).
[0023] Its solution uses alkali-to-slag to replace most of the sodium carbonate in the existing process, thereby reducing the cost of raw materials; at the same time, the process flow is optimized, and iron, fluorine, and aluminum impurities can be removed through a set of processes. The process operation is convenient and helps to save production energy. At the same time, the materials can be recycled, which helps to reduce emissions and save resources. It has good economic benefits and production application value. DETAILED DESCRIPTION
[0024] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.
[0025] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "include..." do not exclude the existence of other identical elements in the process, method, article or device including its elements.
[0026] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.
[0027] The features and performance of the present application are further described in detail below in conjunction with the embodiments.
[0028] Example 1
[0029] This embodiment provides a method for removing impurities from a rare earth solution, which comprises the following steps:
[0030] Preparation of mixed solution: Take the optimal solution and optimal leaching solution obtained in the rare earth production process, and add 9 ml of mixed solution in a mass ratio of 1:1. 3 Total volume driven to 11.52m 3 in a conditioning reaction tank, stirring and mixing to obtain a mixed solution;
[0031] Take samples of the mixed liquid for testing:
[0032] In the mixed solution, REO (rare earth oxide content) is 132 g / L, Fe content is 9.2 g / L, Al content is 0.53% (REO), and F content is 0.48% (REO);
[0033] Slurry preparation: Take 1241kg (i.e. 720kg dry slag weight) of alkali-converted slag (water content 42%) obtained from the rare earth production process, add water (0.72m 3 ) to obtain slurry (1.5m 3 ),spare;
[0034] Acid consumption for iron removal: within 0.5 to 1 hour, slowly add 1m 3 The pH of the system reaches 1.5-2, then steam is passed into the conditioning reaction tank to raise the temperature to above 80°C, and then 0.5m of slag is continuously pumped into the tempering reaction tank within 0.25-0.5h. 3 , the pH of the system is stabilized at 3.5-4, and the iron impurities are removed through reaction to obtain the first material;
[0035] Fluorine and aluminum removal: slowly add 36kg of industrial sodium carbonate and 72kg of calcium carbonate to the first material, stabilize the pH of the system at 5-5.5, continue stirring and reacting for 0.5h to obtain the second material, then add acidic flocculant polyacrylamide to the second material, stop stirring, clarify for 1h, obtain impurity removal liquid (supernatant) and slag (bottom slag and water mixture), pump the impurity removal liquid into the conditioning and F removal tank; 1m slag 3 Pour into the optimal dissolution reaction tank and cool for later use;
[0036] The obtained impurity removal liquid was sampled and tested:
[0037] In the impurity removal liquid, REO is 126g / L, Fe and Al contents are less than 0.01% (REO), and F content is less than 0.03% (REO), which meets the qualified standards.
[0038] Slag recovery: according to the mass ratio of 1:2, add 1m of slag into the optimal solution tank. 3 and clean water 2m 3 , stir and slowly add 0.6m 3 Hydrochloric acid, during which the exhaust is turned on to keep the temperature in the optimal solution tank at about 20°C. After the acid is added, the reaction is continued for 0.5h, and the pH of the system reaches 0.5-1. Then a small amount of hydrochloric acid is added to continue the reaction for 0.33h, and the pH of the system reaches 0.5. The reaction is continued for 0.5h, and the pH of the system is maintained at 0.5, and the reaction is completed;
[0039] After the reaction is completed, add acidic flocculant polyacrylamide, stop stirring, and precipitate for 1 hour to obtain a decontamination solution (supernatant) and decontamination residue;
[0040] Testing of impurity removal solution:
[0041] In the impurity removal solution, the acidity (H + ) is 0.19moL / L, REO is 126g / L, Fe content is 6.8g / L, Al content is 0.374% (REO), F content is 0.31% (REO);
[0042] Impurity removal solution (supernatant) about 2.8m 3 The impurity-removed slag is pumped into the superior solution storage tank; after the impurity-removed superior slag is washed 4 times (the second washing water is used as the washing water of the first washing, and so on), the plate and frame filtration is used to obtain 623 kg of impurity-removed superior slag (dry slag (relative to before filtration)); the impurity-removed superior slag (dry slag) is sent to the cerium-rich slag warehouse;
[0043] Testing of impurity-free molten slag (dry slag):
[0044] The PN (praseodymium-neodymium) distribution of the impurity-free slag (dry slag) is 1.74% (REO), which meets the production requirements (less than 1.8%).
[0045] Example 2
[0046] This embodiment provides a method for removing impurities from a rare earth solution, which comprises the following steps:
[0047] Preparation of mixed solution: Take the optimal solution and optimal leaching solution obtained in the rare earth production process, and mix them in a mass ratio of 1:1 for a total of 8 ml 3 Total volume driven to 11.52m 3 in a conditioning reaction tank, stirring and mixing to obtain a mixed solution;
[0048] Take samples of the mixed liquid for testing:
[0049] In the mixed solution, REO (rare earth oxide content) is 129 g / L, Fe content is 8.8 g / L, Al content is 0.52% (REO), and F content is 0.49% (REO);
[0050] Slurry preparation: Take 1142kg (i.e. 640kg dry slag weight) of the alkali-converted slag (water content 44%) obtained from the rare earth production process, add water (0.64m 3 ) to obtain slurry (1.4m 3 ),spare;
[0051] Acid consumption for iron removal: within 0.5 to 1 hour, slowly add 0.9m 3 The pH of the system reaches 1.5-2, then steam is passed into the conditioning reaction tank to raise the temperature to above 80°C, and then 0.5m of slag is continuously pumped into the tempering reaction tank within 0.25-0.5h. 3 , the pH of the system is stabilized at 3.5-4, and the iron impurities are removed through reaction to obtain the first material;
[0052] Fluorine and aluminum removal: slowly add 32kg of industrial sodium carbonate and 64kg of calcium carbonate to the first material, stabilize the pH of the system at 5-5.5, continue stirring and reacting for 0.5h to obtain the second material, then add acidic flocculant polyacrylamide to the second material, stop stirring, clarify for 1h, obtain impurity removal liquid (supernatant) and slag (bottom slag and water mixture), pump the impurity removal liquid into the conditioning and F removal storage tank; 1m slag 3 Pour into the optimal dissolution reaction tank and cool for later use;
[0053] The obtained impurity removal liquid was sampled and tested:
[0054] In the impurity removal liquid, REO is 117g / L, Fe and Al contents are less than 0.01% (REO), and F content is less than 0.03% (REO), which meets the qualified standards.
[0055] Slag recovery: according to the mass ratio of 1:2, add 1m of slag into the optimal solution tank. 3 and clean water 2m 3 , stir and slowly add 0.5m 3 Hydrochloric acid, during which the exhaust is turned on to keep the temperature in the optimal solution tank at about 20°C. After the acid is added, the reaction is continued for 0.5h, and the pH of the system reaches 0.5-1. Then a small amount of hydrochloric acid is added to continue the reaction for 0.33h, and the pH of the system reaches 0.5. The reaction is continued for 0.5h, and the pH of the system is maintained at 0.5, and the reaction is completed;
[0056] After the reaction is completed, add acidic flocculant polyacrylamide, stop stirring, and precipitate for 1 hour to obtain a decontamination solution (supernatant) and decontamination residue;
[0057] Testing of impurity removal solution:
[0058] In the impurity removal solution, the acidity (H + ) is 0.20moL / L, REO is 102g / L, Fe content is 6.03g / L, Al content is 0.41% (REO), F content is 0.39% (REO);
[0059] Impurity removal solution (supernatant) about 2.8m 3 The impurity-removed slag is pumped into the superior solution storage tank; after the impurity-removed superior slag is washed 4 times (the second washing water is used as the washing water for the first washing, and so on), the plate and frame filtration is used to obtain 562 kg of impurity-removed superior slag (dry slag), and the impurity-removed superior slag (dry slag) is sent to the cerium-rich slag warehouse;
[0060] Testing of impurity-free molten slag (dry slag):
[0061] The PN (praseodymium-neodymium) distribution of the impurity-free molten slag (dry slag) is 1.69% (REO), which meets the production requirements (less than 1.8%).
[0062] Example 3
[0063] This embodiment provides a method for removing impurities from a rare earth solution, which comprises the following steps:
[0064] Preparation of mixed solution: Take the optimal solution and optimal leaching solution obtained in the rare earth production process, add 1L of the total into a 2L beaker in a 1:1 mass ratio in the laboratory, stir and mix to obtain a mixed solution;
[0065] Take samples of the mixed liquid for testing:
[0066] In the mixed solution, REO (rare earth oxide content) is 123 g / L, Fe content is 9 g / L, Al content is 0.46% (REO), and F content is 0.51% (REO);
[0067] Preparation of slag slurry: Take 145 g (i.e. 80 g dry slag weight) of the alkali-converted slag (water content 45%) obtained by washing in the rare earth production process, add water (80 mL) at a weight ratio of 1:1 to obtain slag slurry (170 mL), and set aside;
[0068] Acid consumption for iron removal: within 0.5 to 1 hour, slowly add 110 mL of slurry into the beaker with the mixed solution until the pH value of the system reaches 1.5 to 2, then turn on the induction cooker and heat it to above 80°C, and then continue to add 70 mL of slurry within 0.25 to 0.5 hour, until the pH value of the system is stabilized at 3.5 to 4, remove iron impurities through reaction, and obtain the first material;
[0069] Fluorine and aluminum removal: slowly add 4g of industrial sodium carbonate and 8g of calcium carbonate to the first material, stabilize the pH of the system at 5-5.5, continue stirring and reacting for 0.5h to obtain the second material, then add acidic flocculant polyacrylamide to the second material, stop stirring, clarify for 1h, and obtain impurity removal liquid (supernatant) and slag (bottom slag-water mixture); separate the slag (100mL) and cool it for later use;
[0070] The obtained impurity removal liquid was sampled and tested:
[0071] In the impurity removal liquid, REO is 98g / L, Fe and Al contents are less than 0.01% (REO), and F content is less than 0.03% (REO), which meets the qualified standards.
[0072] Slag recovery: according to the mass ratio of 1:2, add 100mL of slag and 200mL of clean water into a beaker, stir and slowly add 66mL of hydrochloric acid within 2h, during which the water bath temperature is maintained at about 20℃. After the acid is added, continue to react for 0.5h until the pH value of the system reaches 0.5-1, then add a small amount of hydrochloric acid and continue to react for 0.33h until the pH value of the system reaches 0.5. Continue to react for 0.5h until the pH value of the system is maintained at 0.5, and then the reaction is terminated;
[0073] After the reaction is completed, add acidic flocculant polyacrylamide, stop stirring, and precipitate for 1 hour to obtain a decontamination solution (supernatant) and decontamination residue;
[0074] Testing of impurity removal solution:
[0075] In the impurity removal solution, the acidity (H + ) is 0.18moL / L, REO is 104g / L, Fe content is 7.96g / L, Al content is 0.54% (REO), F content is 0.58% (REO);
[0076] The impurity removal solution (supernatant) is about 260 mL; the impurity removal residue is washed 4 times and filtered to obtain 71 g of impurity removal residue (dry residue);
[0077] Testing of impurity-free molten slag (dry slag):
[0078] The PN (praseodymium-neodymium) distribution of the impurity-free slag (dry slag) is 1.66% (REO), which meets the production requirements (less than 1.8%).
[0079] Comparative Example 1
[0080] This comparative example provides a method for removing impurities from a rare earth solution, which comprises the following steps:
[0081] Preparation of mixed solution: Take the optimal solution and optimal leaching solution obtained in the rare earth production process, add 1L of the total into a 2L beaker in a 1:1 mass ratio in the laboratory, stir and mix to obtain a mixed solution;
[0082] Take samples of the mixed liquid for testing:
[0083] In the mixed solution, REO (rare earth oxide content) is 128.3 g / L, Fe content is 8.5 g / L, Al content is 0.49% (REO), and F content is 0.47% (REO);
[0084] Preparation of slag slurry: Take 137.9 g (i.e., dry slag weight 78.6 g) of alkali-converted slag (water content 43%) obtained by washing in the rare earth production process, add water (80 mL) at a weight ratio of 1:1 to obtain slag slurry (144 mL), and set aside;
[0085] Acid consumption for iron removal: within 0.5 to 1 hour, slowly add 96 mL of slurry into the beaker with the mixed solution until the pH value of the system reaches 1.5 to 2, then turn on the induction cooker and heat it to above 80°C, and then continue to add 48 mL of slurry within 0.25 to 0.5 hour, until the pH value of the system is stabilized at 3.5 to 4, remove iron impurities through reaction, and obtain the first material;
[0086] Fluorine and aluminum removal: slowly add 4g of industrial sodium carbonate and 8g of calcium carbonate to the first material, stabilize the pH of the system at 5-5.5, continue stirring and reacting for 0.5h to obtain the second material, then add acidic flocculant polyacrylamide to the second material, stop stirring, clarify for 1h, and obtain impurity removal liquid (supernatant) and slag (bottom slag-water mixture); separate the slag (100mL) and cool it for later use;
[0087] The obtained impurity removal liquid was sampled and tested:
[0088] In the impurity removal liquid, REO is 106.5g / L, Fe and Al contents are less than 0.01% (REO), and F content is less than 0.03% (REO), which meets the qualified standards.
[0089] Slag recovery: according to the mass ratio of 1:2, add 100mL of slag and 200mL of clean water into a beaker, stir and slowly add 66mL of hydrochloric acid within 2h, during which the water bath temperature is maintained at about 55℃. After the acid is added, continue to react for 0.5h until the pH value of the system reaches 0.5-1, then add 2mL of hydrochloric acid and continue to react for 0.33h until the pH value of the system reaches 0.5. Continue to react for 0.5h until the pH value of the system is maintained at 0.5, and then the reaction is terminated;
[0090] After the reaction is completed, add acidic flocculant polyacrylamide, stop stirring, and precipitate for 1 hour to obtain a decontamination solution (supernatant) and decontamination residue;
[0091] Testing of impurity removal solution:
[0092] In the impurity removal solution, the acidity (H + ) is 0.21moL / L, REO is 106.7g / L, Fe content is 18.42g / L, Al content is 1.12% (REO), F content is 1.11% (REO);
[0093] The impurity removal solution (supernatant) is about 275 mL; the impurity removal residue is washed 4 times and filtered to obtain 65 g of impurity removal residue (dry residue);
[0094] Testing of impurity-free molten slag (dry slag):
[0095] The PN (praseodymium-neodymium) distribution of the impurity-free slag (dry slag) is 1.81% (REO), slightly exceeding the production requirement (less than 1.8%).
[0096] Comparative Example 2
[0097] This comparative example provides a method for removing impurities from a rare earth solution, which comprises the following steps:
[0098] Preparation of mixed solution: Take the optimal solution and optimal leaching solution obtained in the rare earth production process, add 1L of the total into a 2L beaker in a 1:1 mass ratio in the laboratory, stir and mix to obtain a mixed solution;
[0099] Take samples of the mixed liquid for testing:
[0100] In the mixed solution, REO (rare earth oxide content) is 124.7 g / L, Fe content is 9.1 g / L, Al content is 0.44% (REO), and F content is 0.48% (REO);
[0101] Preparation of slag slurry: Take 145.3 g (i.e., dry slag weight 79.2 g) of alkali-converted slag (water content 44.5%) obtained by washing in the rare earth production process, add water (80 mL) at a weight ratio of 1:1 to obtain slag slurry (140 mL), and set aside;
[0102] Acid consumption for iron removal: within 0.5 to 1 hour, slowly add 93 mL of slurry into the beaker with the mixed solution until the pH value of the system reaches 1.5 to 2, then turn on the induction cooker and heat it to above 80°C, and then continue to add 47 mL of slurry within 0.25 to 0.5 hour, until the pH value of the system is stabilized at 3.5 to 4, remove iron impurities through reaction, and obtain the first material;
[0103] Fluorine and aluminum removal: slowly add 4g of industrial sodium carbonate and 4g of calcium carbonate to the first material, stabilize the pH of the system at 5-5.5, continue stirring and reacting for 0.5h to obtain the second material, then add acidic flocculant polyacrylamide to the second material, stop stirring, clarify for 1h, and obtain impurity removal liquid (supernatant) and slag (bottom slag and water mixture);
[0104] The obtained impurity removal liquid was sampled and tested:
[0105] In the impurity removal liquid, REO is 104.8 g / L, and the contents of Fe and Al are both less than 0.01% (REO), which meet the qualified standards; the F content is 0.039% (REO), which slightly exceeds the qualified standards.
[0106] Test Example 1
[0107] The impurity removal effect and impurity dissolution rate of the processes of Examples 1 to 3 were calculated, and the results are shown in Table 1:
[0108] Table 1
[0109]
[0110] If sodium carbonate is used for impurity removal according to the existing process (without alkali slag conversion), the corresponding impurity removal effects in Examples 1 to 3 require at least 230 kg, 200 kg, and 26 g of sodium carbonate, respectively; while the method of the embodiment of the present application can directly reduce the input of sodium carbonate by 84.34%, 84%, and 84.61%, thereby saving raw material costs; at the same time, since the embodiment of the present application does not require the final slag (superior soluble slag (dry slag)) to be put into the alkali conversion station, 10% less liquid alkali and a small amount of hydrochloric acid can be added. In addition, significant results are also achieved in saving energy in terms of steam and electricity, and the product quality can also be guaranteed to be stable and qualified. The impurity dissolution rate of the impurity removal slag is basically below 25%, and the superior soluble PN of the impurity removal slag is also less than 1.8%, reducing the circulation.
[0111] Test Example 2
[0112] The impurity removal effect and impurity dissolution rate of the comparative examples 1 to 2 were calculated, and the results are shown in Table 2:
[0113] Table 2
[0114]
[0115] It can be seen from Comparative Example 1 that in the slag recovery step, the temperature during the optimal dissolution treatment cannot be too high (the temperature in Comparative Example 1 is 55° C.), otherwise it will lead to excessive dissolution of impurities Al, Fe, and F in the impurity removal slag, increasing the amount of slag circulating with impurities, which is not conducive to production. The optimal dissolution operation in this step should be carried out at room temperature;
[0116] The optimal mass ratio of the qualified alkali-converted slag (dry slag) washed with water, sodium carbonate and calcium carbonate used in the process is 20:1:2. In Comparative Example 2, the mass ratio of sodium carbonate and calcium carbonate is 1:1, and the F removal effect becomes worse, slightly exceeding the qualified standard.
[0117] In summary, the embodiments of the present application provide a method for removing impurities from a rare earth solution, wherein alkali-to-slag conversion is used to replace most of the sodium carbonate in the existing process, thereby reducing the cost of raw materials; at the same time, the process flow is optimized, and iron, fluorine, and aluminum impurities can be removed through a set of processes. The process operation is convenient, which helps to save production energy consumption. At the same time, the material can be recycled, which helps to reduce emissions, save resources, and has good economic benefits and production application value.
[0118] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.
Claims
1. A method for removing impurities from a rare earth solution, characterized in that: It includes the following steps: Mixed solution preparation: the preferred solution and preferred leaching solution obtained in the rare earth production process are pumped into a reaction container to form a mixed solution; Preparation of slag slurry: Take the alkali-converted slag obtained in the rare earth production process and add water to prepare slag slurry for use; Acid consumption for iron removal: adding slag slurry to the reaction vessel containing the mixed liquid to reduce the acidity of the system, and then heating up to react to remove iron impurities to obtain the first material; Fluorine and aluminum removal: Sodium carbonate and calcium carbonate are added to the first material, stirred to react, and the second material is obtained. A flocculant is then added to the second material for clarification to obtain a decontamination liquid and slag material. The decontamination liquid is used for subsequent processes such as concentration in rare earth production. Slag recovery: The slag is subjected to a dissolving treatment to obtain a dissolving slag and a decontamination solution. The dissolving slag is sent to a cerium-rich slag warehouse, and the decontamination solution is recovered and reused.
2. The method for removing impurities from a rare earth solution according to claim 1, characterized in that: In the mixed solution preparation step, the volume ratio of the optimal solution to the optimal immersion solution is 1:
1.
3. The method for removing impurities from a rare earth solution according to claim 1, characterized in that: In the slag slurry preparation step, the mass ratio of the alkali-converted slag to water is 1:
1.
4. The method for removing impurities from a rare earth solution according to claim 1, characterized in that: In the acid-consuming iron removal step, slag slurry is added to the mixed solution to adjust the pH value of the system to 1.5-2, and then the temperature is raised to react.
5. The method for removing impurities from a rare earth solution according to claim 1, characterized in that: In the acid-consuming iron removal step, the temperature is raised to above 80° C. for reaction.
6. The method for removing impurities from a rare earth solution according to claim 1, characterized in that: In the method steps, the mass ratio of the water-washed qualified alkali-converted slag, sodium carbonate and calcium carbonate is 20:1:
2.
7. The method for removing impurities from a rare earth solution according to claim 1, characterized in that: In the fluorine and aluminum removal steps, the flocculant used is an acidic flocculant.
8. The method for removing impurities from a rare earth solution according to claim 1, characterized in that: In the slag recovery step, the slag is subjected to a dissolution treatment, which comprises the following steps: Add water to the slag and stir to mix, then add hydrochloric acid to react, add flocculant to precipitate after the reaction to obtain a decontaminated superior solution and superior slag, the decontaminated superior solution is sent to a superior solution storage tank, and the superior slag is sent to a cerium-rich slag warehouse after washing and filtration.
9. The method for removing impurities from a rare earth solution according to claim 1, characterized in that: In the slag recovery step, the slag is subjected to a dissolution treatment at room temperature.