CN111170353A - Method for preparing rare earth fluoride by carbon cycle - Google Patents
Method for preparing rare earth fluoride by carbon cycle Download PDFInfo
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- CN111170353A CN111170353A CN202010082949.6A CN202010082949A CN111170353A CN 111170353 A CN111170353 A CN 111170353A CN 202010082949 A CN202010082949 A CN 202010082949A CN 111170353 A CN111170353 A CN 111170353A
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Abstract
The invention discloses a method for preparing rare earth fluoride by carbon cycle, which comprises the following steps: (1) reacting a fluorine-ammonia composite fluorinating agent with rare earth carbonate at 40-90 ℃, and blowing off reaction liquid with gas in the reaction process to obtain blown off tail gas and a reaction mixture; absorbing carbon dioxide in the blow-off tail gas by using first ammonia water to obtain carbon-removed tail gas and liquid containing ammonium bicarbonate; absorbing the carbon-removed tail gas with water to obtain second ammonia water; (2) carrying out post-treatment on the reaction mixture to obtain rare earth fluoride; and (3) reacting the liquid containing ammonium bicarbonate with rare earth chloride to obtain rare earth carbonate; reacting the rare earth carbonate with a fluorine-ammonia composite fluorinating agent to obtain the rare earth fluoride. The method has high fluorine conversion rate and can realize the cyclic utilization of carbon resources.
Description
Technical Field
The invention relates to a method for preparing rare earth fluoride by carbon cycle.
Background
The production process of the rare earth fluoride comprises a dry process and a wet process. The dry process is to directly fluorinate rare earth oxide in hydrogen fluoride gas to obtain the product. The wet process is to directly add hydrofluoric acid or ammonium bifluoride into the rare earth salt solution to precipitate rare earth fluoride, and then to prepare the product through washing, drying and vacuum dehydration. At present, the wet process is simple and convenient to operate and low in production cost, so that the method is widely applied to preparation of the rare earth fluoride. However, the common wet process has the problems of low fluorine conversion rate, over-standard fluorine content in the wastewater, unorganized emission of carbon dioxide and ammonia and the like.
CN1907859A discloses a method for preparing rare earth fluoride from rare earth oxide. And (2) mixing rare earth oxide with water, heating to obtain rare earth hydroxide powder, adding hydrofluoric acid, performing fluorination reaction, and then settling, filtering, washing and drying to obtain the rare earth fluoride. In order to improve the fluorine conversion rate, the method adopts excessive hydrofluoric acid, so that the fluorine content of the wastewater is high, and the subsequent treatment is difficult.
CN101805008A discloses a preparation method of anhydrous high-purity rare earth fluoride. Reacting a composite fluorinating agent prepared from hydrofluoric acid and ammonia water with rare earth carbonate, and then filtering, washing, dehydrating and drying to obtain the anhydrous high-purity rare earth fluoride. In the method, the molar ratio of the fluorine element to the rare earth element is 3.5-4.5, so that the fluorine content in the wastewater is high, and the wastewater is difficult to treat. In addition, the method fails to recover carbon dioxide and ammonia water, resulting in waste of carbon resources and ammonia resources.
CN1337357A discloses a method for preparing rare earth fluoride. The rare earth fluoride is obtained by reacting a composite fluorinating agent prepared by mixing hydrofluoric acid and ammonia water with feed liquid containing rare earth salt. The method adopts excessive hydrofluoric acid, so that the fluorine content in the wastewater is higher.
CN101700902A discloses a method for producing rare earth fluoride. And (3) directly introducing excessive hydrogen fluoride gas into a closed fluorination furnace to react with the rare earth carbonate to prepare the anhydrous rare earth fluoride. The method needs a furnace body made of fluorine-resistant materials, has high cost and cannot recover carbon dioxide.
Disclosure of Invention
In view of the above, the present invention aims to provide a method for preparing rare earth fluoride by carbon cycle, which can realize the recycling of carbon resources. Furthermore, the invention can recover ammonia gas and realize the recycling of nitrogen resources. The invention adopts the following technical scheme to achieve the aim.
The invention provides a method for preparing rare earth fluoride by carbon cycle, which comprises the following steps:
(1) reacting a fluorine-ammonia composite fluorinating agent with rare earth carbonate at 40-90 ℃, and blowing off reaction liquid with gas in the reaction process to obtain blown off tail gas and a reaction mixture; absorbing carbon dioxide in the blow-off tail gas by using first ammonia water to obtain carbon-removed tail gas and liquid containing ammonium bicarbonate; absorbing the carbon-removed tail gas with water to obtain second ammonia water;
(2) carrying out post-treatment on the reaction mixture to obtain rare earth fluoride; and
(3) reacting liquid containing ammonium bicarbonate with rare earth chloride to obtain rare earth carbonate; reacting the rare earth carbonate with a fluorine-ammonia composite fluorinating agent to obtain rare earth fluoride;
wherein the liquid containing ammonium bicarbonate is slurry containing ammonium bicarbonate crystals or carbonized ammonia water solution,
wherein the fluorine-ammonia composite fluorinating agent comprises a fluorine-containing inorganic substance and ammonia water;
wherein the concentration of the first ammonia water is greater than that of the second ammonia water.
According to the method of the present invention, preferably, the concentration of the first aqueous ammonia is 18 to 23 wt%, and the concentration of the second aqueous ammonia is 9 to 18.5 wt%.
According to the method of the present invention, preferably, the second ammonia is adjusted to the concentration of the first ammonia and then used for absorbing carbon dioxide in the blow-off tail gas.
According to the method of the present invention, preferably, in the fluorine-ammonia composite fluorinating agent, the molar ratio of fluorine ions to ammonia ions is 1: 0.5-1.2.
According to the method, preferably, the fluorine ion concentration in the fluorine-ammonia composite fluorinating agent is 2-15 mol/L.
According to the method of the present invention, preferably, the fluorine-containing inorganic substance is at least one selected from the group consisting of hydrofluoric acid, alkali metal fluoride, ammonium bifluoride and ammonium fluoride.
According to the method, the molar ratio of the rare earth ions in the rare earth carbonate to the fluorine ions in the fluorine-ammonia composite fluorinating agent is preferably 1: 2.9-3.0.
According to the method, preferably, the gas is used for stripping until the pH value of the reaction solution is 7-7.5; the gas used is air or nitrogen.
According to the method of the present invention, preferably, the post-processing comprises: and carrying out solid-liquid separation on the reaction mixture to obtain a filter cake and filtrate, and drying the filter cake to obtain the rare earth fluoride.
According to the method of the present invention, preferably, the rare earth element of the rare earth carbonate is selected from one or more of lanthanum, cerium, praseodymium, neodymium and yttrium.
Detailed Description
The present invention will be further described with reference to the following specific examples, but the scope of the present invention is not limited thereto.
"wt%" of the present invention means weight percent.
The invention adopts the reaction of fluorine-ammonia composite fluorinating agent and rare earth carbonate to prepare rare earth fluoride. The rare earth element of the rare earth carbonate may be selected from one or more of lanthanum, cerium, praseodymium, neodymium and yttrium, for example lanthanum carbonate, lanthanum cerium carbonate or yttrium carbonate. According to one embodiment of the invention, the rare earth carbonate is lanthanum carbonate. According to another embodiment of the present invention, the rare earth carbonate is lanthanum cerium carbonate. According to yet another embodiment of the invention, the rare earth carbonate is yttrium carbonate. The rare earth carbonate can be prepared by a conventional method or a commercially available product.
The rare earth carbonate in the present invention may contain some other substances, but the content of the rare earth carbonate in terms of REO is 35 to 60 wt%, preferably 38 to 55 wt%, more preferably 39 to 52 wt%. This facilitates the recovery of carbon resources and the promotion of the fluorination process.
The fluorine-ammonia composite fluorinating agent comprises fluorine-containing inorganic substances and ammonia water. According to one embodiment of the present invention, the fluorine-ammonia composite fluorinating agent is a mixed solution of a fluorine-containing inorganic substance and aqueous ammonia. The fluorine-containing inorganic substance may be at least one selected from hydrofluoric acid, alkali metal fluoride, ammonium bifluoride, and ammonium fluoride. Examples of alkali metal fluorides include, but are not limited to, sodium fluoride, potassium fluoride, and the like. In certain embodiments, the fluorine-containing inorganic substance may be selected from at least one of hydrofluoric acid, sodium fluoride, ammonium bifluoride, and ammonium fluoride. According to one embodiment of the invention, the fluorine-containing inorganic substance is hydrofluoric acid. According to another embodiment of the invention, the inorganic fluorine-containing substance is ammonium bifluoride. The invention finds that the fluorine-containing inorganic substances are beneficial to improving the conversion rate of fluorine and realizing the recycling of carbon resources.
In the fluoroammonia mixed fluorinating agent of the present invention, the molar ratio of fluorine ions to ammonia ions may be 1:0.5 to 1.2, preferably 1:0.52 to 1.2, and more preferably 1:0.55 to 1.15. The fluorine concentration in the fluorine-ammonia composite fluorinating agent is 2-15 mol/L, preferably 2-13 mol/L, and more preferably 2-10 mol/L. Thus being beneficial to improving the fluorine conversion rate and the recycling of carbon resources.
In the invention, the molar ratio of the rare earth ions in the rare earth carbonate to the fluorine ions in the fluorine-ammonia composite fluorinating agent can be 1: 2.9-3.0, preferably 1: 2.99-3.0, and more preferably 1: 2.99-3.0. Therefore, the fluorine content in the wastewater can be reduced on the premise of fluorine conversion rate, and the cyclic utilization of carbon resources is facilitated.
The generation of rare earth fluoride increases with the increase of fluorine ions, but when the fluorine ions increase to a certain degree, the solubility of the rare earth fluoride increases, so that the yield of the rare earth fluoride is reduced, and the raw material waste is caused. Too low fluorine ion can lead the rare earth carbonate not to be completely converted into the rare earth fluoride, thereby influencing the yield of the rare earth fluoride and being not beneficial to generating the rare earth fluoride with large particles. The invention adopts the fluorine-ammonia mixed fluorinating agent, can promote the generation of the rare earth fluoride without reducing the yield of the rare earth fluoride, and the generated rare earth fluoride has large particles and is easy to filter.
The reaction temperature of the fluorine-ammonia composite fluorinating agent and the rare earth carbonate can be 40-90 ℃, preferably 42-90 ℃, and more preferably 50-70 ℃. Therefore, the fluorination reaction can be promoted, and the influence of ammonia evaporation on the fluorination effect and the cyclic utilization of carbon resources is avoided.
In the reaction process of the fluorine-ammonia composite fluorinating agent and the rare earth carbonate, gas is used for blowing off reaction liquid (a mixture formed by the fluorine-ammonia composite fluorinating agent and the rare earth carbonate) to obtain blowing off tail gas and a reaction mixture. Stripping with gas until the pH value of the reaction solution is 7-7.5, preferably 7-7.4, and more preferably 7-7.3. The gas used may be air or nitrogen, preferably air. The method blows off carbon dioxide generated by the reaction, thereby realizing that the chemical equilibrium moves towards the direction of the rare earth fluoride and being beneficial to the complete reaction of the fluorinating agent and the rare earth carbonate.
And carrying out post-treatment on the reaction mixture to obtain the rare earth fluoride. The post-treatment comprises the following steps: and carrying out solid-liquid separation on the reaction mixture to obtain a filter cake and filtrate, and drying the filter cake to obtain the rare earth fluoride. The solid-liquid separation step and the drying step are conventional processes in the field, and are not described again here. Because the invention can form large-particle rare earth fluoride, the rare earth fluoride solid can be separated by adopting the conventional filtering method. In addition, the method has high fluorine conversion rate, so that the fluorine content in the filtrate is extremely low, and the method is favorable for subsequent treatment.
Absorbing carbon dioxide in the blow-off tail gas by using first ammonia water to obtain carbon-removed tail gas and liquid containing ammonium bicarbonate. The concentration of the first ammonia water is 18-23 wt%, preferably 19-23 wt%, and more preferably 21-22 wt%. The ammonia water with higher concentration is favorable for fully absorbing the carbon dioxide in the blow-off tail gas, thereby avoiding the waste of carbon resources. In addition, the liquid containing ammonium bicarbonate obtained in the way is suitable for directly reacting with rare earth chloride to obtain rare earth carbonate, and further recycling carbon resources. The ammonium bicarbonate containing liquid may be a slurry or a carbonated aqueous ammonia solution containing ammonium bicarbonate crystals, preferably a slurry containing ammonium bicarbonate crystals. When the concentration of ammonium bicarbonate is very high, ammonium bicarbonate is crystallized to obtain slurry containing ammonium bicarbonate crystals. When the concentration of ammonium bicarbonate is very low, a carbonized ammonia aqueous solution is formed.
Reacting the liquid containing ammonium bicarbonate with rare earth chloride to obtain the rare earth carbonate. Specifically, the liquid containing ammonium bicarbonate is reacted with a solution containing rare earth chloride to obtain rare earth carbonate. CN101805008A discloses the above process, which is incorporated herein in its entirety. The rare earth chloride solution reacts with the liquid containing ammonium bicarbonate, and then the rare earth carbonate is obtained through precipitation.
The rare earth chloride is the same as the rare earth element of the rare earth carbonate, so that the generation cost can be reduced, and the circular production can be realized. For example, the rare earth carbonate is lanthanum carbonate and the rare earth chloride used is lanthanum chloride. The rare earth carbonate is lanthanum cerium carbonate, and the rare earth chloride is lanthanum cerium chloride.
Reacting rare earth carbonate obtained by reacting liquid containing ammonium bicarbonate with rare earth chloride with a fluorine-ammonia composite fluorinating agent to obtain rare earth fluoride. The reaction conditions were as described above. Therefore, closed-loop circulation of carbon resources can be realized, and carbon dioxide emission is reduced.
And absorbing the carbon-removed tail gas with water to obtain second ammonia water. The fluorine-ammonia composite fluorinating agent comprises fluorine-containing inorganic substances and ammonia water, wherein the blow-off tail gas is recovered by using the first ammonia water, and the generated carbon-removed tail gas contains a certain amount of ammonia gas and can be absorbed by using water to form the second ammonia water. The concentration of the second ammonia water may be 9 to 18.5 wt%, preferably 12 to 17.9 wt%, and more preferably 15 to 17.8 wt%. The concentration of the first aqueous ammonia for absorbing carbon dioxide gas is greater than the concentration of the second aqueous ammonia. And adjusting the second ammonia water to the concentration of the first ammonia water, and then absorbing the carbon dioxide in the blow-off tail gas. The method of adjustment may be a concentration method or mixing with ammonia water of higher concentration. According to one embodiment of the invention, the second ammonia is directly fed to the first ammonia to absorb the carbon dioxide in the de-tail gas. This avoids ammonia emissions during the production process.
In the following examples, the fluorine conversion rate is equal to the weight of fluorine in the rare earth fluoride/the weight of fluorine in the fluoroammonia complex fluorinating agent × 100%.
Carbon resource utilization ratio (weight of rare earth carbonate calculated as carbon dioxide-weight of discharged carbon dioxide)/weight of rare earth carbonate calculated as carbon dioxide × 100%.
Example 1
The fluorine-ammonia composite fluorinating agent in the embodiment is obtained by mixing hydrofluoric acid and ammonia water, wherein the molar ratio of fluorine ions to ammonia ions is 1:1. The rare earth carbonate is mixed rare earth carbonate, and the content of REO in the mixed rare earth carbonate is 44.7 wt%.
198L of a fluorine-ammonia composite fluorinating agent with fluorine concentration of 4mol/L reacts with 100kg of mixed rare earth carbonate at the temperature of 60 ℃, reaction liquid is blown off by air in the reaction process until the pH value of the reaction liquid is 7.1, and blown off tail gas and a reaction mixture are obtained; absorbing carbon dioxide in the stripping tail gas by using first ammonia water with the concentration of 23 wt% to obtain the carbon-removed tail gas and slurry containing ammonium bicarbonate crystals.
And filtering the reaction mixture to obtain a filter cake and filtrate, and drying the filter cake to obtain the rare earth fluoride. The primary fluorine conversion was calculated.
And mixing the slurry containing ammonium bicarbonate crystals with a mixed rare earth chloride solution (the rare earth elements are the same as the mixed rare earth carbonate), reacting, and precipitating to obtain the rare earth carbonate. The obtained rare earth carbonate is used as a raw material to react with the fluorine-ammonia composite fluorinating agent to obtain the rare earth fluoride. The secondary fluorine conversion was calculated.
Absorbing the carbon-removed tail gas by using water to obtain second ammonia water with the concentration of 18 wt%.
Example 2
The fluorine-ammonia composite fluorinating agent in the embodiment is obtained by mixing hydrofluoric acid, sodium fluoride and ammonia water, wherein the molar ratio of fluorine ions to ammonia ions is 1: 0.5. The rare earth carbonate is lanthanum carbonate hydroxide, and the REO content in the lanthanum carbonate hydroxide is 47.6 wt%.
Reacting 146L of a fluoroammonia composite fluorinating agent with fluorine concentration of 6mol/L with 100kg of lanthanum carbonate hydroxide at 40 ℃, and blowing off reaction liquid by using air in the reaction process until the pH value of the reaction liquid is 7.3 to obtain blown-off tail gas and a reaction mixture; absorbing carbon dioxide in the stripping tail gas by using first ammonia water with the concentration of 21 wt% to obtain carbon-removed tail gas and a carbonized ammonia water solution.
And filtering the reaction mixture to obtain a filter cake and filtrate, and drying the filter cake to obtain the lanthanum fluoride. The primary fluorine conversion was calculated.
And mixing and reacting the carbonized ammonia water solution and the lanthanum chloride solution, and precipitating to obtain the lanthanum carbonate. The obtained lanthanum carbonate is used as a raw material to react with the fluorine-ammonia composite fluorinating agent to obtain lanthanum fluoride. The secondary fluorine conversion was calculated.
Absorbing the carbon-removed tail gas by using water to obtain 17.5 wt% of second ammonia water.
Example 3
The fluorine-ammonia composite fluorinating agent in the embodiment is obtained by mixing sodium fluoride and ammonia water, wherein the molar ratio of fluorine ions to ammonia ions is 1: 1.2. The rare earth carbonate is lanthanum cerium carbonate, and the REO content in the lanthanum cerium carbonate is 43.2 wt%.
Reacting 96L of a fluorine-ammonia composite fluorinating agent with the fluorine concentration of 8mol/L with 100kg of lanthanum cerium carbonate at the temperature of 80 ℃, and blowing off reaction liquid by using air in the reaction process until the pH value of the reaction liquid is 7 to obtain blown off tail gas and a reaction mixture; absorbing the carbon dioxide in the stripping tail gas by using first ammonia water with the concentration of 20 wt% to obtain the carbon-removed tail gas and slurry containing ammonium bicarbonate crystals.
And filtering the reaction mixture to obtain a filter cake and a filtrate, and drying the filter cake to obtain lanthanum cerium fluoride. The primary fluorine conversion was calculated.
Mixing the slurry containing ammonium bicarbonate crystals with a lanthanum cerium chloride solution, reacting, precipitating to obtain lanthanum cerium carbonate, and reacting the obtained lanthanum cerium carbonate serving as a raw material with the ammonium fluoride composite fluorinating agent to obtain lanthanum cerium fluoride. The secondary fluorine conversion was calculated.
Absorbing the carbon-removed tail gas by using water to obtain 17.8 wt% of second ammonia water.
Example 4
The fluorine-ammonia composite fluorinating agent in the embodiment is obtained by mixing ammonium bifluoride and ammonia water, wherein the molar ratio of fluorine ions to ammonia ions is 1: 0.8. The rare earth carbonate is lanthanum oxycarbonate, and the REO content in the lanthanum oxycarbonate is 51.3 wt%.
472L of a fluoroamine composite fluorinating agent with fluorine concentration of 2mol/L and 100kg of lanthanum oxycarbonate react at 90 ℃, and air is used for blowing off reaction liquid in the reaction process until the pH value of the reaction liquid is 7.1, so that blown off tail gas and a reaction mixture are obtained; absorbing the carbon dioxide in the stripping tail gas by using first ammonia water with the concentration of 19 wt% to obtain the carbon-removed tail gas and slurry containing ammonium bicarbonate crystals.
And filtering the reaction mixture to obtain a filter cake and filtrate, and drying the filter cake to obtain the lanthanum fluoride. The primary fluorine conversion was calculated.
And mixing the slurry containing ammonium bicarbonate crystals with a lanthanum chloride solution, reacting, precipitating to obtain lanthanum carbonate, and reacting the obtained lanthanum carbonate serving as a raw material with the fluoroamine composite fluorinating agent to obtain lanthanum fluoride. The secondary fluorine conversion was calculated.
Absorbing the carbon-removed tail gas by using water to obtain second ammonia water with the concentration of 18.2 wt%.
Example 5
The fluorine-ammonia composite fluorinating agent in the embodiment is obtained by mixing hydrofluoric acid and ammonia water, wherein the molar ratio of fluorine ions to ammonia ions is 1: 1.1. The rare earth carbonate is lanthanum carbonate, and the REO content in the lanthanum carbonate is 45.3 wt%.
Reacting 83L of a fluorine-ammonia composite fluorinating agent with the fluorine concentration of 10mol/L with 100kg of lanthanum carbonate at 70 ℃, and blowing off reaction liquid by using air in the reaction process until the pH value of the reaction liquid is 7.2 to obtain blown-off tail gas and a reaction mixture; absorbing carbon dioxide in the stripping tail gas by using first ammonia water with the concentration of 18 wt% to obtain carbon-removed tail gas and a carbonized ammonia water solution.
And filtering the reaction mixture to obtain a filter cake and filtrate, and drying the filter cake to obtain the lanthanum fluoride. The primary fluorine conversion was calculated.
And mixing and reacting the carbonized ammonia water solution and the lanthanum chloride solution, and precipitating to obtain lanthanum carbonate, wherein the obtained lanthanum carbonate can be used as a raw material to react with the fluorine-ammonia composite fluorinating agent to obtain the lanthanum fluoride. The secondary fluorine conversion was calculated.
Absorbing the carbon-removed tail gas by using water to obtain 17.6 wt% of second ammonia water.
Example 6
The fluorine-ammonia composite fluorinating agent in the embodiment is obtained by mixing hydrofluoric acid and ammonia water, wherein the molar ratio of fluorine ions to ammonia ions is 1: 1.1. The rare earth carbonate is yttrium carbonate, and the content of REO in the yttrium carbonate is 48.7 wt%.
Reacting 215L of a fluoroamine composite fluorinating agent with fluorine concentration of 6mol/L with 100kg of yttrium carbonate at 50 ℃, and blowing off reaction liquid by using air in the reaction process until the pH value of the reaction liquid is 7.1 to obtain blown-off tail gas and a reaction mixture; absorbing carbon dioxide in the stripping tail gas by using first ammonia water with the concentration of 21 wt% to obtain the carbon-removed tail gas and slurry containing ammonium bicarbonate crystals.
And filtering the reaction mixture to obtain a filter cake and filtrate, and drying the filter cake to obtain yttrium fluoride. The primary fluorine conversion was calculated.
And mixing the slurry containing ammonium bicarbonate crystals with a yttrium chloride solution, reacting, precipitating to obtain yttrium carbonate, and reacting the obtained yttrium carbonate serving as a raw material with the fluorine-ammonia composite fluorinating agent to obtain yttrium fluoride. The secondary fluorine conversion was calculated.
Absorbing the carbon-removed tail gas by using water, and then emptying to obtain 17.8 wt% of second ammonia water.
TABLE 1
Example 7
The conditions were the same as in example 1 except for the following steps:
and adjusting the concentration of the second ammonia water to the corresponding concentration of the first ammonia water, and absorbing the carbon dioxide in the stripping tail gas. Absorbing the carbon-removed tail gas by using water to obtain new second ammonia water with the concentration of 17.5 wt%.
Example 8
The conditions were the same as in example 2 except for the following steps:
and adjusting the concentration of the second ammonia water to the corresponding concentration of the first ammonia water, and absorbing the carbon dioxide in the stripping tail gas. Absorbing the carbon-removed tail gas by using water to obtain new second ammonia water with the concentration of 17.1 wt%.
Example 9
The conditions were the same as in example 3 except for the following steps:
and adjusting the concentration of the second ammonia water to the corresponding concentration of the first ammonia water, and absorbing the carbon dioxide in the stripping tail gas. Absorbing the carbon-removed tail gas by using water to obtain new second ammonia water with the concentration of 18.3 wt%.
Example 10
The conditions were the same as in example 4 except for the following steps:
and adjusting the concentration of the second ammonia water to the corresponding concentration of the first ammonia water, and absorbing the carbon dioxide in the stripping tail gas. Absorbing the carbon-removed tail gas by using water to obtain new second ammonia water with the concentration of 18.1 wt%.
Example 11
The conditions were the same as in example 5 except for the following steps:
and adjusting the concentration of the second ammonia water to the corresponding concentration of the first ammonia water, and absorbing the carbon dioxide in the stripping tail gas. Absorbing the carbon-removed tail gas by using water to obtain new second ammonia water with the concentration of 17.9 wt%.
Example 12
The conditions were the same as in example 6 except for the following steps:
and adjusting the concentration of the second ammonia water to the corresponding concentration of the first ammonia water, and absorbing the carbon dioxide in the stripping tail gas. Absorbing the carbon-removed tail gas by using water to obtain new second ammonia water with the concentration of 18.2 wt%.
TABLE 2
The present invention is not limited to the above-described embodiments, and any variations, modifications, and substitutions which may occur to those skilled in the art may be made without departing from the spirit of the invention.
Claims (10)
1. The method for preparing rare earth fluoride by carbon cycle is characterized by comprising the following steps:
(1) reacting a fluorine-ammonia composite fluorinating agent with rare earth carbonate at 40-90 ℃, and blowing off reaction liquid with gas in the reaction process to obtain blown off tail gas and a reaction mixture; absorbing carbon dioxide in the blow-off tail gas by using first ammonia water to obtain carbon-removed tail gas and liquid containing ammonium bicarbonate; absorbing the carbon-removed tail gas with water to obtain second ammonia water;
(2) carrying out post-treatment on the reaction mixture to obtain rare earth fluoride; and
(3) reacting liquid containing ammonium bicarbonate with rare earth chloride to obtain rare earth carbonate; reacting the rare earth carbonate with a fluorine-ammonia composite fluorinating agent to obtain rare earth fluoride;
wherein the liquid containing ammonium bicarbonate is slurry containing ammonium bicarbonate crystals or carbonized ammonia water solution,
wherein the fluorine-ammonia composite fluorinating agent comprises a fluorine-containing inorganic substance and ammonia water;
wherein the concentration of the first ammonia water is greater than that of the second ammonia water.
2. The method of claim 1, wherein the concentration of the first aqueous ammonia is 18 to 23 wt% and the concentration of the second aqueous ammonia is 9 to 18.5 wt%.
3. The method of claim 2, wherein the second ammonia is adjusted to the concentration of the first ammonia and then used to absorb carbon dioxide from the blow-off gas.
4. The method according to any one of claims 1 to 3, wherein the molar ratio of fluorine ions to ammonium ions in the fluoroammonia complex fluorinating agent is 1:0.5 to 1.2.
5. The method according to any one of claims 1 to 3, wherein the fluorine ion concentration in the fluoroamine complex fluorinating agent is 2 to 15 mol/L.
6. The method according to any one of claims 1 to 3, wherein the fluorine-containing inorganic substance is at least one selected from the group consisting of hydrofluoric acid, alkali metal fluoride, ammonium bifluoride and ammonium fluoride.
7. The method according to any one of claims 1 to 3, wherein the molar ratio of the rare earth ions in the rare earth carbonate to the fluorine ions in the fluoroammonia complex fluorinating agent is 1:2.9 to 3.0.
8. The method according to any one of claims 1 to 3, wherein the stripping is carried out with a gas until the pH of the reaction solution is 7 to 7.5; the gas used is air or nitrogen.
9. A method according to any one of claims 1 to 3, wherein the post-treatment comprises: and carrying out solid-liquid separation on the reaction mixture to obtain a filter cake and filtrate, and drying the filter cake to obtain the rare earth fluoride.
10. A process according to any one of claims 1 to 3, wherein the rare earth element of the rare earth carbonate is selected from one or more of lanthanum, cerium, praseodymium, neodymium and yttrium.
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| CN113428962A (en) * | 2021-06-23 | 2021-09-24 | 中国北方稀土（集团）高科技股份有限公司 | Method for removing fluorine and oxalate in ammonium sulfate wastewater |
| CN114180613A (en) * | 2021-12-13 | 2022-03-15 | 包头稀土研究院 | Method for preparing rare earth oxide by recycling ammonia and carbon and application of rare earth oxide |
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| CN1337357A (en) * | 2000-08-08 | 2002-02-27 | 赣州有色冶金研究所 | Method of preparing rare earth fluoride |
| TW200904755A (en) * | 2007-05-11 | 2009-02-01 | Agc Seimi Chemical Co Ltd | Method of recovering rare earth element |
| CN101805008A (en) * | 2010-04-26 | 2010-08-18 | 赣州虔东稀土集团股份有限公司 | Anhydrous high-purity rare earth fluoride and preparation method thereof |
| CN104117682A (en) * | 2013-04-27 | 2014-10-29 | 北京有色金属研究总院 | Method for preparing narrow range rare earth oxide with controllable particle size |
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| CN106517294A (en) * | 2015-09-09 | 2017-03-22 | 有研稀土新材料股份有限公司 | Method for preparing metal oxide |
| CN107828963A (en) * | 2017-10-31 | 2018-03-23 | 四川英创环保科技有限公司 | A kind of utilization process of rare earth oxide production process carbon dioxide and ammonium |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113428962A (en) * | 2021-06-23 | 2021-09-24 | 中国北方稀土（集团）高科技股份有限公司 | Method for removing fluorine and oxalate in ammonium sulfate wastewater |
| CN114180613A (en) * | 2021-12-13 | 2022-03-15 | 包头稀土研究院 | Method for preparing rare earth oxide by recycling ammonia and carbon and application of rare earth oxide |
| CN114180613B (en) * | 2021-12-13 | 2024-04-12 | 包头稀土研究院 | Method for preparing rare earth oxide by recycling ammonia and carbon and application of rare earth oxide |
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