A method for extracting and removing iron from rare earth feed liquid in a hydrochloric acid system of bastnasite using a mixed neutral extractant

Abstract

The present invention belongs to the field of removing iron from bastnasite, and particularly relates to a method for extracting and removing iron from rare earth liquor in a hydrochloric acid system of bastnasite by using a mixed neutral extractant. The general treatment process is to add alkaline substances such as ammonia water and ammonium bicarbonate to the rare earth leaching solution to neutralize the acidity and callback to remove iron to obtain ferric hydroxide slag. The ferric hydroxide slag obtained by this method contains 18%-25% of REO, resulting in a large loss of rare earth. The present invention uses a mixed neutral extractant to extract and remove iron from rare earth liquor in a hydrochloric acid system of bastnasite. Specifically, tributyl phosphate and extractant A are combined to synergistically remove iron under certain acidity conditions, and the separation effect of neutral molecules of iron and rare earth cations is excellent, effectively removing iron impurities in the rare earth liquor. The ferric chloride solution obtained in the stripping section can be used as a raw material for producing iron red and water clarifying agent, and the neutral mixed extractant can be recycled after being stripped with water.

Description

Technical Field

[0001] The present invention belongs to the field of iron removal from bastnasite, and specifically relates to a method for extracting and removing iron from rare earth feed liquid in a hydrochloric acid system of bastnasite by using a mixed neutral extractant. Background Art

[0002] Rare earths are important strategic resources and play a crucial role in promoting a country's economic development and scientific and technological progress. In the rare earth preparation process, after bastnasite is leached by oxidative roasting, hydrochloric acid and sodium hydroxide mixed method, a leaching solution with an acidity of 0.5 - 0.8 mol / L and a rare earth concentration of 250 - 280 g / L is obtained. This leaching solution contains 15 - 30 g / L of non-rare earth impurity iron ions. Generally, the traditional treatment process is to add alkaline substances such as ammonia water and ammonium bicarbonate to the rare earth leaching solution to neutralize the acidity and callback for iron removal to obtain ferric hydroxide slag. The ferric hydroxide slag obtained by this method contains 18% - 25% of REO, resulting in a large loss of rare earths.

[0003] Patent CN 104342559 A mixes 10 - 50 vol% of N235 (tri(octyl / decyl)alkyl tertiary amine), 10 - 30 vol% of a modifier (sec-octanol or isooctanol) with the balance of a diluent for iron removal from zirconium oxide waste liquid. However, the N235 (tri(octyl / decyl)alkyl tertiary amine) used in this extractant system is a basic extractant that can only extract anions, and the iron ions need to be converted into anions. Therefore, the acidity of this system is often difficult to control.

[0004] In the field of rare earth extraction, N235 and p507 are often used for stepwise extraction and iron removal. However, as the organic phase is used repeatedly through multiple extraction - stripping cycles, iron impurities continuously accumulate in the organic phase, resulting in the loss of the extraction ability of p507 and N235 extractants in the organic phase, and the extractants show the phenomenon of "poisoning", which affects the extraction ability of N235 and p507. At the same time, the system is prone to emulsification, which affects the phase separation effect of the extraction system, thus causing waste of resources and increasing production costs. Therefore, there is an urgent need for a new extractant system to remove iron ions from the leaching solution and avoid waste of rare earth resources. Summary of the Invention

[0005] In view of the above problems, the present invention provides a method for extracting and removing iron from rare earth feed liquid in a hydrochloric acid system of bastnasite by using a mixed neutral extractant. Specifically, tributyl phosphate (TPB) and isooctanol are combined, and it is found that after the combination of the two, there is a synergistic effect on the extraction of iron from rare earth feed liquid in a hydrochloric acid system.

[0006] During the extraction process, the mixed neutral extractant has the advantage of only extracting neutral molecules without extracting rare earth cations. Therefore, it is necessary to adjust the acidity of the rare earth leaching solution. The inventors of the present invention found that only when the acidity of the rare earth feed liquid is controlled within the range of 1.5 - 1.8 mol / L, iron ions can form neutral molecules. At this time, the separation effect of the mixed neutral extractant on the neutral molecules of iron and rare earth cations is excellent, which has very important industrial value.

[0007] Specifically, the present invention provides a method for extracting and removing iron from a rare earth feed liquid in a cerium fluorocarbonate hydrochloric acid system. The mixed neutral extractant is used to extract the rare earth feed liquid in the hydrochloric acid system. The acidity of the rare earth feed liquid in the hydrochloric acid system is 1.5 - 1.8 mol / L. The mixed neutral extractant is composed of tributyl phosphate (TPB), extractant A, and kerosene;

[0008] The extractant A is one or more of isooctanol, cyclohexanone, amyl acetate, and furfural.

[0009] In the present invention, the extractant A used is isooctanol.

[0010] As shown in Comparative Examples 1 - 3 of the present invention, when using the mixed neutral extractant system, tributyl phosphate (TPB) and isooctanol are mixed and used for co-extraction and iron removal. The two extractants affect each other, and the iron removal efficiency is the best under the acidity conditions of the present invention in the hydrochloric acid system. Too high or too low acidity will reduce the iron removal effect of the mixed organic phase, and even the iron removal effect cannot be achieved.

[0011] Since the extractant selected in the present invention is a mixed neutral extractant, a very complex extraction process occurs during the extraction process:

[0012] (Neutral mixed extractant) + H + + 4Cl - + Fe 3+ = [(Neutral mixed extractant).FeHCl4]

[0013] The stripping process is: [(Neutral mixed extractant).FeHCl4] + H2O = (Neutral mixed extractant) + H3O + + 4Cl - + Fe 3+

[0014] It can be seen from the above reaction formula that acidity has an important influence on the formation of the complex FeHCl4. When the acidity is too high, the iron ions form FeCl 4- complex anions, and the neutral extractant cannot extract them. When the acidity is too low, the extraction of Fe 3+ is incomplete.

[0015] In the present invention, tributyl phosphate, extractant A and kerosene are formulated according to a volume ratio of 20%-30%: 20%-30%: 40%-60%.

[0016] Further, tributyl phosphate, extractant A and kerosene are formulated according to a volume ratio of 30%: 30%: 40%.

[0017] In the present invention, the method for extracting and removing iron from rare earth feed liquid in a cerium fluoride hydrochloric acid system specifically includes the following steps:

[0018] (1) Take the rare earth leaching solution obtained by oxidative roasting and mixed leaching of cerium fluoride ore;

[0019] (2) Add hydrochloric acid to the rare earth leaching solution in step (1) to adjust the acidity to 1.5 - 1.8 mol / L; obtain the rare earth feed liquid in the hydrochloric acid system;

[0020] (3) Perform 12 - stage countercurrent extraction on the rare earth feed liquid in the hydrochloric acid system with a mixed neutral extractant, where the extraction section has 6 stages, the scrubbing section has 3 stages, and the stripping section has 3 stages; both the scrubbing agent and the stripping agent are water.

[0021] In the technical solution of the present invention, during countercurrent extraction, control the flow ratio of the organic phase, rare earth leaching solution, scrubbing agent and stripping agent to be 0.8 - 1: 0.5 - 1: 0.2 - 0.4: 0.5 - 0.8 to extract and remove iron from the rare earth leaching solution.

[0022] Further, during countercurrent extraction, control the flow ratio of the organic phase, rare earth leaching solution, scrubbing agent and stripping agent to be 1: 0.5 - 1: 0.2: 0.5

[0023] In the present invention, obtain ferric chloride solution as the raw material for producing iron red and water clarifying agent in the stripping section, and the neutral mixed extractant is recycled after being stripped with water.

[0024] In the present invention, before mixing the tributyl phosphate in the mixed neutral extractant, wash it with sodium carbonate solution to remove the impurities monobutyl phosphate (MBP) and dibutyl phosphate (DBP) in the tributyl phosphate.

[0025] In the present invention, in the rare earth leaching solution, the rare earth concentration is 250 - 280 g / L, and the iron ion concentration is 15 - 30 g / L.

[0026] In the present invention, the water temperature of the water used in step (3) is 50 - 53 °C.

[0027] In the present invention, the rare earth leaching solution obtained by the mixed leaching method refers to the leaching solution obtained after treatment with hydrochloric acid and sodium hydroxide.

[0028] In the present invention, the flow ratio refers to the ratio of the flow rates between each fluid.

[0029] The beneficial effects of the present invention are as follows:

[0030] The present invention discovers a new mixed neutral extractant for extracting and removing iron from rare earth liquor in the cerium fluoride carbonate hydrochloric acid system. TBP in this extractant can cooperate with isooctanol, and has an excellent separation effect on neutral molecules of iron and rare earth cations, with very important industrial value. At the same time, the present invention provides a suitable acidity range for using the mixed neutral extractant to extract and remove iron from rare earth liquor in the cerium fluoride carbonate hydrochloric acid system. Within this acidity range, it can ensure that the mixed neutral extractant can effectively extract and remove iron. The ferric chloride solution obtained in the stripping section can be used as a raw material for producing iron red and water clarifying agent, and the neutral mixed extractant can be recycled after being stripped with water. Description of the Drawings

[0031] Figure 1 : Process flow chart. Detailed Embodiments

[0032] The technical solutions of the present invention will be further described below through specific embodiments, but the scope of protection is not limited only to the descriptions made.

[0033] The process flow charts of Examples 1 - 3 are as Figure 1 shown.

[0034] Example 1

[0035] 1. Take the rare earth leaching solution obtained by oxidizing and roasting cerium fluoride carbonate ore and leaching it by the (hydrochloric acid and sodium hydroxide) mixing method. The acidity of this leaching solution is detected to be 0.8 mol / L, the rare earth concentration is 264.6 g / L, and the iron ion concentration is 15.2 g / L.

[0036] 2. According to the analysis and detection results in Step 1, add hydrochloric acid to the above rare earth leaching solution to adjust the acidity to 1.5 mol / L.

[0037] 3. The present invention selects two neutral extractants, TBP and isooctanol. The organic phase TBP needs to be washed with 5% sodium carbonate aqueous solution to remove impurities MBP and DBP in TBP.

[0038] 4. Take the above - washed TBP, isooctanol, and kerosene respectively, and prepare a neutral mixed extractant according to the ratio of 30%:30%:40%.

[0039] 5. Use the neutral mixed extractant prepared in Step 4 to perform 12 - stage counter - current extraction on the rare earth leaching solution obtained in Step 2, where the extraction section is 6 stages, the washing section is 3 stages, and the stripping section is 3 stages. The washing agent and stripping agent are both selected as hot water at 52°C.

[0040] 6. Control the flow ratio of the organic phase, rare earth leaching solution, detergent, and stripping agent at 1:1:0.2:0.5 to carry out iron extraction from the rare earth leaching solution. Among them, the rare earth leaching solution after iron extraction is obtained in the extraction section, and this rare earth leaching solution is used for impurity removal in the next process. Ferric chloride solution is obtained in the stripping section and can be used as raw materials for producing iron red, etc.

[0041] 7. The analysis and detection data are as follows:

[0042]

[0043] Example 2

[0044] 1. Take the rare earth leaching solution obtained by oxidative roasting of bastnasite and leaching with the (hydrochloric acid and sodium hydroxide) mixing method. The acidity of this leaching solution is detected to be 0.5 mol / L, the rare earth concentration is 278.4 g / L, and the iron ion concentration is 29.6 g / L.

[0045] 2. According to the results of the analysis and detection in step 1, add hydrochloric acid to the above rare earth leaching solution to adjust the acidity to 1.8 mol / L.

[0046] 3. The present invention selects two neutral extractants, TBP and isooctanol. It is necessary to wash the organic phase TBP with 5% sodium carbonate aqueous solution to remove impurities MBP and DBP in TBP.

[0047] 4. Take the above washed TBP, isooctanol, and kerosene respectively, and prepare a neutral mixed extractant according to the ratio of 25%:30%:45%.

[0048] 5. Use the neutral mixed extractant prepared in step 4 to carry out 12-stage countercurrent extraction on the rare earth leaching solution obtained in step 2, where the extraction section has 6 stages, the washing section has 3 stages, and the stripping section has 3 stages. Among them, both the detergent and the stripping agent are selected as hot water at 50 °C.

[0049] 6. Control the flow ratio of the organic phase, rare earth leaching solution, detergent, and stripping agent at 1:0.5:0.2:0.5 to carry out iron extraction from the rare earth leaching solution. Among them, the rare earth leaching solution after iron extraction is obtained in the extraction section, and this rare earth leaching solution is used for impurity removal in the next process. Ferric chloride solution is obtained in the stripping section and can be used as raw materials for producing iron red, etc.

[0050] 7. The analysis and detection data are as follows:

[0051]

[0052] Example 3

[0053] 1. Take the rare earth leaching solution obtained by oxidizing and roasting bastnasite and leaching with a mixture of (hydrochloric acid and sodium hydroxide). The acidity of this leaching solution was measured to be 0.6 mol / L, the rare earth concentration was 252.8 g / L, and the iron ion concentration was 18.9 g / L.

[0054] 2. According to the results of the analysis and detection in step 1, add hydrochloric acid to the above rare earth leaching solution to adjust the acidity to 1.6 mol / L.

[0055] 3. In this invention, two neutral extractants, TBP and isooctanol, are selected. The organic phase TBP needs to be washed with a 5% sodium carbonate aqueous solution to remove impurities MBP and DBP in TBP.

[0056] 4. Take the washed TBP, isooctanol, and kerosene mentioned above and prepare a neutral mixed extractant according to the ratio of 20%:20%:60%.

[0057] 5. Use the neutral mixed extractant prepared in step 4 to perform 12 - stage counter - current extraction on the rare earth leaching solution obtained in step 2, where the extraction section has 6 stages, the washing section has 3 stages, and the stripping section has 3 stages. The washing agent and stripping agent are both 51°C hot water.

[0058] 6. Control the flow ratio of the organic phase, rare earth leaching solution, washing agent, and stripping agent at 1:0.8:0.2:0.5 to extract and remove iron from the rare earth leaching solution. In the extraction section, the rare earth leaching solution after iron removal from rare earth is obtained, and this rare earth leaching solution is used for impurity removal in the next process. In the stripping section, a ferric chloride solution is obtained, which can be used as a raw material for producing iron red, etc.

[0059] 7. The analysis and detection data are as follows:

[0060]

[0061] Comparative Example 1

[0062] 1. Take the rare earth leaching solution obtained by oxidizing and roasting bastnasite and leaching with a mixture of (hydrochloric acid and sodium hydroxide). The acidity of this leaching solution was measured to be 0.8 mol / L, the rare earth concentration was 264.6 g / L, and the iron ion concentration was 15.2 g / L.

[0063] 2. In this invention, two neutral extractants, TBP and isooctanol, are selected. The organic phase TBP needs to be washed with a 5% sodium carbonate aqueous solution to remove impurities MBP and DBP in TBP.

[0064] 3. Take the washed TBP, isooctanol, and kerosene mentioned above and prepare a neutral mixed extractant according to the ratio of 30%:30%:40%.

[0065] 4. Use the neutral mixed extractant prepared in Step 3 to perform 12-stage countercurrent extraction on the rare earth leaching solution obtained in Step 2, with 6 stages in the extraction section, 3 stages in the washing section, and 3 stages in the stripping section. The washing agent and the stripping agent are both hot water at 53°C.

[0066] 5. Control the flow ratio of the organic phase, rare earth leaching solution, washing agent, and stripping agent at 1:1:0.2:0.5 to perform iron removal from the rare earth leaching solution. In the extraction section, the rare earth leaching solution after iron removal from rare earths is obtained, and this rare earth leaching solution is used for impurity removal in the next process. In the stripping section, a ferric chloride solution can be obtained as a raw material for producing iron red, etc.

[0067] 6. The analysis and detection data are as follows:

[0068]

[0069] Comparative Example 2

[0070] 1. Take the rare earth leaching solution obtained by oxidative roasting of bastnasite and leaching by the (hydrochloric acid and sodium hydroxide) mixed method. The acidity of this leaching solution is detected to be 0.73 mol / L, the rare earth concentration is 273.4 g / L, and the iron ion concentration is 16.3 g / L.

[0071] 2. According to the results of the analysis and detection in Step 1, add hydrochloric acid to the above rare earth leaching solution to adjust the acidity to 1.6 mol / L.

[0072] 3. Wash the organic phase TBP with a 5% aqueous sodium carbonate solution to remove impurities MBP and DBP in TBP.

[0073] 4. Take the above washed TBP and kerosene and prepare a neutral mixed extractant in a ratio of 30%:70%.

[0074] 5. Use the neutral extractant prepared in Step 4 to perform 12-stage countercurrent extraction on the rare earth leaching solution obtained in Step 2, with 6 stages in the extraction section, 3 stages in the washing section, and 3 stages in the stripping section. The washing agent and the stripping agent are both hot water at 50°C. It is found that the clarified chamber in the extraction section is divided into 3 immiscible liquid phases. Therefore, it is not suitable to use the extractant TBP alone for iron removal in the hydrochloric acid system.

[0075] Comparative Example 3

[0076] 1. Take the rare earth leaching solution obtained by oxidative roasting of bastnasite and leaching by the (hydrochloric acid and sodium hydroxide) mixed method. The acidity of this leaching solution is detected to be 0.8 mol / L, the rare earth concentration is 264.6 g / L, and the iron ion concentration is 15.2 g / L.

[0077] 2. According to the results of the analysis and detection in Step 1, add hydrochloric acid to the above rare earth leaching solution to adjust the acidity to 1.5 mol / L.

[0078] 3. Prepare a neutral extractant by mixing isooctanol and kerosene at a ratio of 30%:70%.

[0079] 4. Use the neutral extractant prepared in step 3 to perform 12-stage countercurrent extraction on the rare earth leaching solution obtained in step 2, with 6 stages in the extraction section, 3 stages in the washing section, and 3 stages in the stripping section. The washing agent and the stripping agent are both 50°C hot water.

[0080] 5. Control the flow ratio of the organic phase, rare earth leaching solution, washing agent, and stripping agent at 1:1:0.2:0.5 to extract and remove iron from the rare earth leaching solution. In the extraction section, obtain the rare earth leaching solution after iron removal, which is used for impurity removal in the next process. In the stripping section, obtain a ferric chloride solution that can be used as a raw material for producing iron red, etc.

[0081] 6. The analysis and detection data are as follows:

[0082]

[0083] Conclusion: For the rare earth leaching solution of bastnasite with a concentration of 1.5 - 1.8 mol / L, use a neutral mixed extractant (20% - 30%) TBP + (20% - 30%) one of (isooctanol, cyclohexanone, amyl acetate, furfural) + (40% - 60%) kerosene to perform 12-stage countercurrent extraction. Strictly control the flow ratio of the organic phase, rare earth leaching solution, washing agent, and stripping agent at 1:0.5 - 1:0.2:0.5. It is possible to obtain a rare earth leaching solution almost free of iron at the first stage and a 99.99% ferric chloride solution at the 11th stage. The experimental data show that this neutral mixed extractant has the characteristic of only extracting iron and not extracting rare earth cations under the above process conditions. This process can not only reduce the loss of rare earths in the general iron removal process but also recover iron and can produce products such as iron red and water clarifying agents.

[0084] The above has described the present invention in detail, but the content described is only the preferred embodiment of the present invention and cannot be considered as limiting the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of the present invention application should still fall within the scope covered by the patent of the present invention.

Claims

1. A method for extracting and removing iron from rare earth liquor in the hydrochloric acid system of bastnasite, characterized in that, The rare earth feed liquid in hydrochloric acid system is extracted by using a mixed neutral extractant, wherein the acidity of the rare earth feed liquid in hydrochloric acid system is 1.5 - 1.8 mol / L; the mixed neutral extractant is composed of tributyl phosphate, extractant A and kerosene; The extractant A is isooctanol, and tributyl phosphate, extractant A and kerosene are prepared according to the volume ratio of 20% - 30%: 20% - 30%: 40% - 60%.

2. The method according to claim 1, characterized in that, Tributyl phosphate, extractant A and kerosene are prepared according to the volume ratio of 30%: 30%: 40%.

3. The method according to any one of claims 1-2, characterized in that, Specifically, it includes the following contents: (1) Take the rare earth leaching solution obtained by oxidative roasting and mixed leaching of bastnasite; (2) Add hydrochloric acid to the rare earth leaching solution in step (1) to adjust the acidity to 1.5 - 1.8 mol / L; obtain the rare earth feed liquid in hydrochloric acid system; (3) The rare earth feed liquid in hydrochloric acid system is subjected to 12 - stage counter - current extraction with the mixed neutral extractant, where the extraction section has 6 stages, the washing section has 3 stages, and the stripping section has 3 stages; both the washing agent and the stripping agent are water.

4. The method according to claim 3, wherein During counter - current extraction, control the flow ratio of the organic phase, rare earth leaching solution, washing agent and stripping agent to be 0.8 - 1: 0.5 - 1: 0.2 - 0.4: 0.5 - 0.8 to extract and remove iron from the rare earth leaching solution; further, during counter - current extraction, control the flow ratio of the organic phase, rare earth leaching solution, washing agent and stripping agent to be 1: 0.5 - 1: 0.2: 0.

5.

5. The method according to claim 3, characterized in that, In the stripping section, obtain ferric chloride solution as the raw material for producing iron red and water clarifying agent, and the mixed neutral extractant is recycled after water stripping.

6. The method according to claim 3, characterized in that Before mixing, the tributyl phosphate in the mixed neutral extractant is washed with sodium carbonate solution to remove impurities MBP and DBP in the tributyl phosphate.

7. The method according to claim 3, characterized in that, In the rare earth leaching solution, the rare earth concentration is 250 - 280 g / L, and the concentration of iron ions is 15 - 30 g / L.

8. The method according to claim 3, wherein The water temperature of the water used in step (3) is 50 - 53 °C.

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