Preparation method of rare earth fluoride

Abstract

The invention provides a preparation method of rare earth fluoride. The preparation method comprises the following steps: mixing a rare earth raw material with a fluorinating reagent, reacting under a ball milling condition, and then carrying out optional calcining treatment to obtain the rare earth fluoride. The method disclosed by the invention can be used for obtaining the rare earth trifluoride and the composite rare earth fluoride, is simple to operate, mild in condition, green, safe and efficient, and is suitable for industrial large-scale production.

Description

Technical Field

[0001] This invention relates to the field of rare earth materials technology, and in particular to a method for preparing rare earth fluorides. Background Technology

[0002] Rare earth fluorides are excellent inorganic materials with a series of unique physicochemical properties, and they have wide applications in catalysis, optical materials, biomedicine and other fields.

[0003] Currently, there are two main processes for preparing rare earth fluorides: wet and dry processes. The wet process involves reacting rare earth hydroxide or rare earth chloride aqueous solutions with hydrofluoric acid. Because it's a reaction between aqueous solutions, the rare earth fluorides prepared using this process easily form compounds such as water of crystallization, resulting in high impurity water and oxygen content. If rare earth oxides are used as raw materials, an acid dissolution step is added, which easily introduces various additional impurities, resulting in high water and oxygen content, and the process is lengthy with large wastewater treatment volumes. There are two common dry processes. One involves reacting hydrogen fluoride with rare earth oxides; however, the hydrogen fluoride tail gas produced by this method is difficult to treat. If the tail gas is not properly treated, it can pose a danger to humans. The other dry process utilizes the reaction of ammonium hydrogen fluoride with rare earth oxides. This method is a solid-phase reaction, which has the problem of incomplete reaction and requires deammoniation and dehydration treatment, making the process more complex.

[0004] Therefore, it is essential to develop an efficient, green, safe, and easily industrially scalable method for synthesizing rare earth fluorides. Summary of the Invention

[0005] To address one of the aforementioned technical problems in the prior art, this invention provides an efficient, universal, green, and safe method for preparing rare earth fluorides.

[0006] The technical solution of the present invention is as follows: A method for preparing rare earth fluorides includes the following steps: mixing rare earth raw materials with a fluorinating agent and reacting them under ball milling conditions, followed by an optional calcination treatment step to obtain rare earth fluorides.

[0007] According to some embodiments of the present invention, the rare earth elements include light rare earth elements and heavy rare earth elements. Examples of light rare earth elements in the present invention include, but are not limited to, lanthanum, cerium, praseodymium, neodymium, etc. Examples of heavy rare earth elements in the present invention include, but are not limited to, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, yttrium, etc.

[0008] According to some embodiments of the present invention, the rare earth raw materials include one or more of rare earth oxides, rare earth carbonates, rare earth hydroxides, and rare earth inorganic salts (e.g., hydrochlorides, sulfates, nitrates, etc.).

[0009] In this invention, when the rare earth element is lanthanum or neodymium, the rare earth raw material is preferably a rare earth oxide, rare earth carbonate, or rare earth hydroxide. When the rare earth element is cerium or praseodymium, the rare earth raw material is preferably a rare earth carbonate, rare earth hydroxide, or rare earth inorganic salt.

[0010] According to some embodiments of the present invention, the fluorinating agent comprises ammonium fluoride and / or alkali metal fluorides. According to some embodiments of the present invention, the fluorinating agent comprises at least one selected from ammonium fluoride, potassium fluoride, sodium fluoride, and cesium fluoride.

[0011] In this invention, the rare earth fluoride is a rare earth trifluoride or a composite rare earth fluoride. In some embodiments, the composite rare earth fluoride is AB₂F₇, AB₂F₇:C, ABF₄, or ABF₄:C, where A represents ammonium ion or alkali metal ion, B represents a first rare earth metal ion, C represents a second rare earth metal ion (C ion exists in a doped form and has the same valence state as B ion), and F represents fluoride ion. In some embodiments, B represents yttrium ion or lutetium ion, and C represents terbium ion. In some specific embodiments, the composite rare earth fluoride is one or more of NH4Y2F7, NH4Y2F7:Tb, β-NaYF4, β-NaYF4:Tb, α-KYF4, α-KYF4:Tb, CsY2F7, CsY2F7:Tb, α-NaLuF4:Tb, β-NaLuF4:Tb, α-KLuF4:Tb, and α-CsLu2F7:Tb.

[0012] According to some embodiments of the present invention, the molar ratio of the rare earth raw material to the fluorinating agent is 1:(3.5~12), for example 1:3.5, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, etc.

[0013] According to some embodiments of the present invention, the ball milling is carried out in the presence of ball milling media and ball milling solvent.

[0014] In some embodiments, the milling media are made of agate, zirconium oxide, or silicon nitride.

[0015] In some embodiments, the grinding media is selected from one or more combinations of grinding balls with a diameter of 6 to 20 mm; for example, it may be a combination of grinding balls with diameters of 6 mm, 10 mm, and 15 mm.

[0016] In some embodiments, the mass of the ball milling media is 1 to 20 times the total mass of the rare earth raw materials and fluorinating reagents, for example, 1, 2, 5, 8, 10, 12, 15, 18, 20 times, etc.

[0017] In some embodiments, the milling solvent includes at least one of water and C1-C6 alcohol solvents. In some preferred embodiments, the milling solvent includes water and / or ethanol. In some specific embodiments, the milling solvent includes water. In some specific embodiments, the milling solvent includes anhydrous ethanol.

[0018] In some embodiments, the ratio of the total mass of the rare earth raw material and the fluorinating reagent to the volume of the ball milling solvent is (0.3~2):1g / mL, for example, 0.3:1g / mL, 0.5:1g / mL, 0.8:1g / mL, 1:1g / mL, 1.2:1g / mL, 1.5:1g / mL, 1.8:1g / mL, 2:1g / mL, etc.

[0019] According to some embodiments of the present invention, the rotational speed of the ball mill is 200-800 rpm, for example, 200 rpm, 300 rpm, 400 rpm, 500 rpm, 550 rpm, 600 rpm, 700 rpm, 800 rpm, etc. According to some embodiments of the present invention, the rotational speed of the ball mill is 500-800 rpm. According to some embodiments of the present invention, the rotational speed of the ball mill is 550-800 rpm.

[0020] According to some embodiments of the present invention, the reaction is carried out in a ball mill.

[0021] In some embodiments, the ball mill rotates at a speed of 200 to 800 rpm, such as 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, etc.

[0022] In some embodiments, the grinding jar of the ball mill is made of agate, zirconium oxide, or silicon nitride, with agate being preferred.

[0023] In some embodiments, the volume of the ball milling solvent is 1 to 10% of the volume of the ball milling jar, preferably 2 to 5%.

[0024] In some embodiments, the ball milling time is 20-60 hours. In some embodiments, the ball milling temperature is 15-40°C. In some embodiments, the ball milling is intermittent. In some embodiments, the intermittent ball milling is performed with a stop of 8-12 minutes every 55-65 minutes.

[0025] In some embodiments, the reaction temperature is 15–40°C. In some embodiments, the reaction time is 20–80 hours. In some embodiments, the reaction time is 22–70 hours.

[0026] According to some embodiments of the present invention, the method further includes the steps of washing and drying the reaction products after the reaction is completed.

[0027] In some embodiments, the solvent used for washing includes at least one of water and C1-C6 alcohol solvents. In some embodiments, the solvent used for washing includes water and / or ethanol. In some specific embodiments, the solvent used for washing includes water. In some specific embodiments, the solvent used for washing includes anhydrous ethanol.

[0028] In some embodiments, the drying temperature is 30~100°C.

[0029] According to some embodiments of the present invention, the calcination temperature is 300~500℃, for example 300℃, 350℃, 400℃, 450℃, 500℃, etc.

[0030] According to some embodiments of the present invention, the calcination time is 8 to 12 hours.

[0031] According to some embodiments of the present invention, the rare earth element is selected from any one of samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium. The preparation method includes: mixing the rare earth raw material with ammonium fluoride and reacting it under ball milling conditions; the reaction product is then calcined to obtain rare earth trifluoride. In some embodiments, the reaction product is washed and dried before calcination. In some embodiments, both ball milling and calcination are carried out under a protective atmosphere. The protective atmosphere includes, but is not limited to, at least one of nitrogen, helium, and argon.

[0032] According to some embodiments of the present invention, the rare earth element is selected from any one of lanthanum, cerium, praseodymium, and neodymium. The preparation method includes: mixing the rare earth raw material with ammonium fluoride and reacting it under ball milling conditions to obtain a rare earth trifluoride. According to some embodiments of the present invention, the method further includes: washing and drying the reaction product to obtain the rare earth trifluoride.

[0033] According to some embodiments of the present invention, the rare earth element is selected from any one or a combination of two of terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and yttrium. The preparation method includes: mixing the rare earth raw material with the fluorinating reagent and reacting them under ball milling conditions to obtain a composite rare earth fluoride. In some embodiments, the ball milling is carried out under a protective atmosphere. The protective atmosphere includes, but is not limited to, at least one of nitrogen, helium, and argon. In some embodiments, the method further includes: washing and drying the reaction product to obtain the composite rare earth fluoride.

[0034] Compared with the prior art, the present invention has the following beneficial effects: 1. The method of the present invention can efficiently prepare rare earth trifluorides and composite rare earth fluorides by ball milling rare earth raw materials and fluorinating reagents together, and the water content in the product rare earth fluorides can be controlled at a low level.

[0035] 2. This invention uses mechanochemical processes such as ball milling, which is simple, controllable, has a short cycle, is easy to industrialize, and is suitable for large-scale production.

[0036] 3. The method of the present invention avoids the use of highly toxic raw materials such as hydrogen fluoride in traditional dry synthesis, does not require harsh conditions such as high temperature and high pressure, and can obtain rare earth fluorides through ball milling reaction at room temperature and pressure, which significantly reduces energy consumption, saves costs, improves safety, and is green and environmentally friendly. Attached Figure Description

[0037] Figure 1 These are the XRD spectra of the rare earth trifluorides prepared in Examples 1 to 4.

[0038] Figure 2 These are the XRD patterns of the rare earth trifluorides prepared in Examples 5 to 8.

[0039] Figure 3 These are the XRD patterns of the rare earth trifluorides prepared in Examples 9 to 12.

[0040] Figure 4 These are the XRD patterns of the rare earth trifluorides prepared in Examples 13 to 16.

[0041] Figure 5 These are the XRD spectra of the composite rare earth fluorides prepared in Examples 17 to 24.

[0042] Figure 6 These are photographs of the fluorescence emission of the composite rare earth fluorides prepared in Examples 17 to 24 under 365nm ultraviolet light excitation.

[0043] Figure 7 These are the XRD spectra of the composite rare earth fluorides prepared in Examples 25 to 28.

[0044] Figure 8 These are the XRD spectra of the composite rare earth fluorides prepared in Examples 29 to 30.

[0045] Figure 9 The XRD patterns are of the products prepared in Comparative Examples 1 to 4. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way.

[0047] Unless otherwise specified, the experimental methods used in this invention are conventional methods; the raw materials, reagents, instruments, etc. used are commercially available unless otherwise specified.

[0048] The method for preparing rare earth fluorides provided by the present invention includes the following steps: mixing rare earth raw materials with fluorinating reagents and reacting them under ball milling conditions, followed by an optional calcination treatment step to obtain rare earth fluorides.

[0049] As a specific embodiment of the present invention, the present invention provides a method for preparing light rare earth fluorides, comprising the following steps: A certain amount of rare earth raw materials, fluorinating reagents, and grinding balls are added to a ball mill jar, along with a small amount of solvent. The jar is then sealed and fixed on a ball mill. Certain ball milling parameters are set for the ball milling reaction. After the reaction is complete, the product is washed and dried to obtain a rare earth trifluoride. The rare earth element is selected from any one of lanthanum, cerium, praseodymium, and neodymium. For light rare earth elements such as lanthanum and neodymium, the preferred rare earth raw materials are rare earth oxides, rare earth carbonates, rare earth hydroxides, or rare earth inorganic salts. For light rare earth elements such as cerium and praseodymium, the preferred rare earth raw materials are rare earth carbonates, rare earth hydroxides, or rare earth inorganic salts.

[0050] Furthermore, in the above-mentioned method for preparing light rare earth fluorides, the fluorinating agent is ammonium fluoride, potassium fluoride, or sodium fluoride. In this invention, in the above-mentioned method for preparing light rare earth fluorides, when the fluorinating agent is an alkali metal fluoride such as potassium fluoride or sodium fluoride, the reaction is preferably carried out in an inert atmosphere (e.g., argon, helium, nitrogen, or a mixture thereof).

[0051] Furthermore, in the above-mentioned method for preparing light rare earth fluorides, the molar ratio of rare earth raw materials to fluorinating reagents is 1:(6~12).

[0052] Furthermore, in the above-mentioned method for preparing light rare earth fluorides, the solvent is water or anhydrous ethanol.

[0053] Furthermore, in the above-mentioned method for preparing light rare earth fluorides, the ratio of the total mass of the rare earth raw material and the fluorinating reagent to the volume of the ball milling solvent is (0.3~2):1g / mL.

[0054] Furthermore, in the above-mentioned method for preparing light rare earth fluorides, the grinding jar is made of agate.

[0055] Furthermore, in the above-mentioned method for preparing light rare earth fluorides, the grinding ball is an agate grinding ball.

[0056] Furthermore, in the above-mentioned method for preparing light rare earth fluorides, the grinding ball size is any one or a combination of several of the diameters from 6 mm to 20 mm.

[0057] Furthermore, in the above-mentioned method for preparing light rare earth fluorides, the mass of the grinding balls is 1 to 20 times the mass of the raw materials.

[0058] Furthermore, in the above-mentioned method for preparing light rare earth fluorides, the ball milling reaction temperature is 15~40℃.

[0059] Furthermore, in the above-mentioned method for preparing light rare earth fluorides, the ball milling reaction time is 20 to 60 hours.

[0060] Furthermore, in the above-mentioned method for preparing light rare earth fluorides, the ball mill rotation speed and revolution speed are 200 rpm to 800 rpm.

[0061] Furthermore, in the above-mentioned method for preparing light rare earth fluorides, water and anhydrous ethanol are used for washing.

[0062] Furthermore, in the above-mentioned method for preparing light rare earth fluorides, the drying temperature is 60~90℃.

[0063] As another specific embodiment of the present invention, the present invention provides a method for preparing heavy rare earth fluorides, comprising the following steps: A certain amount of rare earth raw materials, ammonium fluoride, and grinding balls are added to a ball mill jar, and a small amount of solvent is added to the ball mill jar. Then, the ball mill jar is sealed under an inert atmosphere (e.g., argon atmosphere) and fixed on a ball mill. A certain ball milling parameter is set to carry out the ball milling reaction. After the reaction is completed, the product is washed and dried. The product obtained is a complex formed by rare earth trifluoride and ammonium fluoride (NH4REF4 or NH4RE2F7, where RE is rare earth). The material is calcined under an inert atmosphere (e.g., argon atmosphere) to obtain the corresponding rare earth trifluoride. The heavy rare earth is selected from any one of samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium. For heavy rare earth elements such as samarium, europium, gadolinium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium, rare earth oxides are preferred as raw materials. For terbium, rare earth carbonates are preferred as raw materials.

[0064] Furthermore, in the above-mentioned method for preparing heavy rare earth fluorides, the molar ratio of rare earth raw materials to ammonium fluoride is 1:(6~12).

[0065] Furthermore, in the above-mentioned method for preparing heavy rare earth fluorides, the solvent is water or anhydrous ethanol.

[0066] Furthermore, in the above-mentioned method for preparing heavy rare earth fluorides, the ratio of the total mass of the rare earth raw material and ammonium fluoride to the volume of the solvent is (0.3~2):1g / mL.

[0067] Furthermore, in the above-mentioned method for preparing heavy rare earth fluorides, the grinding jar is made of agate.

[0068] Furthermore, in the above-mentioned method for preparing heavy rare earth fluorides, the grinding ball is an agate grinding ball, a zirconia grinding ball, or a silicon nitride grinding ball.

[0069] Furthermore, in the above-mentioned method for preparing heavy rare earth fluorides, the grinding ball size is any one or a combination of several of the diameters from 6 mm to 20 mm.

[0070] Furthermore, in the above-mentioned method for preparing heavy rare earth fluorides, the mass of the grinding balls is 1 to 20 times the mass of the raw materials.

[0071] Furthermore, in the above-mentioned method for preparing heavy rare earth fluorides, the ball milling reaction time is 20 to 60 hours.

[0072] Furthermore, in the above-mentioned method for preparing heavy rare earth fluorides, the ball milling reaction temperature is 15~40℃.

[0073] Furthermore, in the above-mentioned method for preparing heavy rare earth fluorides, the ball mill rotation speed and revolution speed are 200 rpm to 800 rpm.

[0074] Furthermore, in the above-mentioned method for preparing heavy rare earth fluorides, water and anhydrous ethanol are used for washing.

[0075] Furthermore, in the above-mentioned method for preparing heavy rare earth fluorides, the drying temperature is 60~90℃.

[0076] Furthermore, in the above-mentioned method for preparing heavy rare earth fluorides, the calcination temperature is 300℃ to 500℃.

[0077] Furthermore, in the above-mentioned method for preparing heavy rare earth fluorides, the calcination time is 8 to 12 hours.

[0078] As another specific embodiment of the present invention, the present invention provides a method for preparing composite rare earth fluorides, comprising the following steps: A certain amount of rare earth raw materials, fluorinating reagents, and grinding balls are added to a ball mill jar, along with a small amount of solvent. The jar is then sealed and fixed on a ball mill. Certain ball milling parameters are set for the ball milling reaction. After the reaction is complete, the product is washed and dried, yielding a composite rare earth fluoride. The rare earth elements are selected from any one or a combination of two of terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and yttrium. The fluorinating reagent is ammonium fluoride, sodium fluoride, potassium fluoride, cesium fluoride, etc. Further, the rare earth raw materials are rare earth carbonates or rare earth inorganic salts.

[0079] Furthermore, in the above-mentioned method for preparing composite rare earth fluorides, the molar ratio of the rare earth raw material to the fluorinating reagent is 1:(3.5~12).

[0080] Furthermore, in the above-mentioned method for preparing composite rare earth fluorides, the solvent is water or anhydrous ethanol.

[0081] Furthermore, in the above-mentioned method for preparing composite rare earth fluorides, the ratio of the total mass of the rare earth raw material and the fluorinating reagent to the volume of the ball milling solvent is (0.3~2):1g / mL.

[0082] Furthermore, in the above-mentioned method for preparing composite rare earth fluorides, the grinding jar is made of agate.

[0083] Furthermore, in the above-mentioned method for preparing composite rare earth fluorides, the grinding ball is an agate grinding ball.

[0084] Furthermore, in the above-mentioned method for preparing composite rare earth fluorides, the grinding ball size is any one or a combination of several sizes ranging from 6 mm to 20 mm in diameter.

[0085] Furthermore, in the above-mentioned method for preparing composite rare earth fluorides, the mass of the grinding balls is 1 to 20 times the mass of the raw materials.

[0086] Furthermore, in the above-mentioned method for preparing composite rare earth fluorides, the ball milling reaction temperature is 15~40℃.

[0087] Furthermore, in the above-mentioned method for preparing composite rare earth fluorides, the ball milling reaction time is 20 to 60 hours.

[0088] Furthermore, in the above-mentioned method for preparing composite rare earth fluorides, the ball mill rotation speed and revolution speed are 200 rpm to 800 rpm.

[0089] Furthermore, in the above-mentioned method for preparing composite rare earth fluorides, water and anhydrous ethanol are used for washing.

[0090] Furthermore, in the above-mentioned method for preparing composite rare earth fluorides, the drying temperature is 60~90℃.

[0091] Example 1

[0092] (1) Add 3.2581 g of lanthanum oxide, 4.4448 g of ammonium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar; (2) Add 36.77 g of agate ball with a diameter of 6 mm, 23.11 g of agate ball with a diameter of 10 mm and 17.24 g of agate ball with a diameter of 15 mm to the ball mill jar; (3) After sealing the ball mill jar, fix it on the planetary ball mill, set the ball mill speed to 580 revolutions per minute, stop for 10 minutes every 60 minutes for intermittent ball milling, the ball milling reaction time is 40 hours, and the total running time is 46 hours and 40 minutes; (4) After the reaction is complete, remove the ball mill jar, wash the product with deionized water until the supernatant is neutral, then wash it three times with anhydrous ethanol, and transfer the product to a 70°C oven for drying. (5) Perform X-ray diffraction on the dried product, with a scanning angle of 10°-90° and a step frequency of 0.01° / minute. Figure 1 The XRD pattern of the product obtained in this embodiment proves that the reaction product is LaF3.

[0093] Example 2 (1) Add 2.3013 g of cerium carbonate, 4.4448 g of ammonium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar; (2) Add 36.77 g of agate ball with a diameter of 6 mm, 23.11 g of agate ball with a diameter of 10 mm and 17.24 g of agate ball with a diameter of 15 mm to the ball mill jar; (3) After sealing the ball mill jar, fix it on the planetary ball mill, set the ball mill speed to 580 revolutions per minute, stop for 10 minutes every 60 minutes for intermittent ball milling, the ball milling reaction time is 40 hours, and the total running time is 46 hours and 40 minutes; (4) After the reaction is complete, remove the ball mill jar, wash the product with deionized water until the supernatant is neutral, then wash it three times with anhydrous ethanol, and transfer the product to a 70°C oven for drying. (5) Perform X-ray diffraction on the dried product, with a scanning angle of 10°-90° and a step frequency of 0.01° / minute. Figure 2 The XRD pattern of the product obtained in this embodiment proves that the reaction product is CeF3.

[0094] Example 3 (1) Add 2.3092 g of praseodymium carbonate, 4.4448 g of ammonium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar; (2) Add 36.77 g of agate ball with a diameter of 6 mm, 23.11 g of agate ball with a diameter of 10 mm and 17.24 g of agate ball with a diameter of 15 mm to the ball mill jar; (3) After sealing the ball mill jar, fix it on the planetary ball mill, set the ball mill speed to 580 revolutions per minute, stop for 10 minutes every 60 minutes for intermittent ball milling, the ball milling reaction time is 60 hours, and the total running time is 70 hours; (4) After the reaction is complete, remove the ball mill jar, wash the product with deionized water until the supernatant is neutral, then wash it three times with anhydrous ethanol, and transfer the product to a 70°C oven for drying. (5) Perform X-ray diffraction on the dried product, with a scanning angle of 10°-90° and a step frequency of 0.01° / minute. Figure 3 The XRD pattern of the product obtained in this embodiment proves that the reaction product is PrF3.

[0095] Example 4 (1) Add 3.3648 g of neodymium oxide, 4.4448 g of ammonium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar; (2) Add 36.77 g of agate ball with a diameter of 6 mm, 23.11 g of agate ball with a diameter of 10 mm and 17.24 g of agate ball with a diameter of 15 mm to the ball mill jar; (3) After sealing the ball mill jar, fix it on the planetary ball mill, set the ball mill speed to 780 revolutions per minute, stop for 10 minutes every 60 minutes for intermittent ball milling, the ball milling reaction time is 60 hours, and the total running time is 70 hours; (4) After the reaction is complete, remove the ball mill jar, wash the product with deionized water until the supernatant is neutral, then wash it three times with anhydrous ethanol, and transfer the product to a 70°C oven for drying. (5) Perform X-ray diffraction on the dried product, with a scanning angle of 10°-90° and a step frequency of 0.01° / minute. Figure 4 The XRD pattern of the product obtained in this embodiment proves that the reaction product is NdF3.

[0096] Example 5 (1) Add 3.4872 g of samarium oxide, 4.4448 g of ammonium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar; (2) Add 36.77 g of agate ball with a diameter of 6 mm, 23.11 g of agate ball with a diameter of 10 mm and 17.24 g of agate ball with a diameter of 15 mm to the ball mill jar; (3) Transfer the ball mill jar to an argon atmosphere glove box for sealing; (4) Take out the ball mill jar and fix it on the planetary ball mill. Set the ball mill speed to 580 revolutions per minute. Stop the ball mill for 10 minutes every 60 minutes for intermittent ball milling. The ball milling reaction time is 40 hours and the total running time is 46 hours and 40 minutes. (5) After the reaction is complete, remove the ball mill jar, wash the product with deionized water until the supernatant is neutral, then wash it three times with anhydrous ethanol, and transfer the product to a 70°C oven for drying. (6) Transfer the dried product to a tube furnace and calcine it at 500°C for 10 hours under an argon atmosphere, with the heating and cooling rates set at 10°C / minute. (7) The calcined product was subjected to X-ray diffraction with a scanning angle of 10°-90° and a step frequency of 0.01° / minute. Figure 2 The XRD pattern of the product obtained in this embodiment proves that the reaction product is SmF3.

[0097] Example 6 The only difference from Example 5 is step (1): (1) Add 3.5192 g europium oxide, 4.4448 g ammonium fluoride and 10 ml deionized water to a 250 ml agate ball mill jar.

[0098] Example 7 The only difference from Example 5 is step (1): (1) Add 3.625 g of gadolinium oxide, 4.4448 g of ammonium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar.

[0099] Example 8 The only difference from Example 5 is step (1): (1) Add 4.9788 g of terbium carbonate, 4.4448 g of ammonium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar.

[0100] Example 9 The only difference from Example 5 is step (1): (1) Add 3.73 g of dysprosium oxide, 4.4448 g of ammonium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar.

[0101] Example 10 The only difference from Example 5 is step (1): (1) Add 3.7786 g of holmium oxide, 4.4448 g of ammonium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar.

[0102] Example 11 The only difference from Example 5 is step (1): (1) Add 3.8254 g of erbium oxide, 4.4448 g of ammonium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar.

[0103] Example 12 The only difference from Example 5 is step (1): (1) Add 3.8587 g of thulium oxide, 4.4448 g of ammonium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar.

[0104] Example 13 The only difference from Example 5 is step (1): (1) Add 3.9408 g of ytterbium oxide, 4.4448 g of ammonium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar.

[0105] Example 14 The only difference from Example 5 is step (1): (1) Add 3.9793 g of lutetium oxide, 4.4448 g of ammonium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar.

[0106] Example 15 The only difference from Example 5 is step (1): (1) Add 2.2581 g of yttrium oxide, 4.4448 g of ammonium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar.

[0107] Example 16 The only difference from Example 5 is step (1): (1) Add 1.3791 g of scandium oxide and 4.4448 g of ammonium fluoride to a 250 ml agate ball mill jar.

[0108] Example 17 (1) Add 3.5784 g of yttrium carbonate, 4.4448 g of ammonium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar; (2) Add 36.77 g of agate ball with a diameter of 6 mm, 23.11 g of agate ball with a diameter of 10 mm and 17.24 g of agate ball with a diameter of 15 mm to the ball mill jar; (3) Transfer the ball mill jar to an argon atmosphere glove box for sealing; (4) Take out the ball mill jar and fix it on the planetary ball mill. Set the ball mill speed to 580 revolutions per minute. Stop the ball mill for 10 minutes every 60 minutes for intermittent ball milling. The ball milling reaction time is 40 hours and the total running time is 46 hours and 40 minutes. (5) After the reaction is complete, remove the ball mill jar, wash the product with deionized water until the supernatant is neutral, then wash it three times with anhydrous ethanol, and transfer the product to a 70°C oven for drying. (6) Perform X-ray diffraction on the dried product, with a scanning angle of 10°-90° and a step frequency of 0.01° / minute. Figure 5 The XRD pattern of the product obtained in this embodiment proves that the reaction product is NH4Y2F7.

[0109] Example 18 The only difference from Example 17 is step (1): (1) Add 3.5784 g of yttrium carbonate, 0.4979 g of terbium carbonate, 4.4448 g of ammonium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar; XRD analysis confirmed that the reaction product was NH4Y2F7:Tb.

[0110] Example 19 The only difference from Example 17 is step (1): (1) Add 3.5784 g of yttrium carbonate, 3.3592 g of sodium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar.

[0111] XRD analysis confirmed that the reaction product was β-NaYF4.

[0112] Example 20 The only difference from Example 17 is step (1): (1) Add 3.5784 g of yttrium carbonate, 0.4979 g of terbium carbonate, 3.6951 g of sodium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar.

[0113] XRD analysis confirmed that the reaction product was β-NaYF4:Tb.

[0114] Example 21 The only difference from Example 17 is step (1): (1) Add 3.5784 g of yttrium carbonate, 4.648 g of potassium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar.

[0115] XRD analysis confirmed that the reaction product was α-KYF4.

[0116] Example 22 The only difference from Example 17 is step (1): (1) Add 3.5784 g of yttrium carbonate, 0.4979 g of terbium carbonate, 5.1128 g of potassium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar.

[0117] XRD analysis confirmed that the reaction product was α-KYF4:Tb.

[0118] Example 23 The only difference from Example 17 is step (1): (1) Add 3.5784 g of yttrium carbonate, 12.152 g of cesium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar.

[0119] XRD confirmed that the reaction product was CsY2F7.

[0120] Example 24 The only difference from Example 17 is step (1): (1) Add 3.5784 g of yttrium carbonate, 0.4979 g of terbium carbonate, 13.367 g of cesium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar.

[0121] XRD analysis confirmed that the reaction product was CsY2F7:Tb.

[0122] Example 25 The only difference from Example 17 is step (1): (1) Add 1.9947 g of lutetium sulfate, 0.2240 g of terbium carbonate and 1.0078 g of sodium fluoride to a 250 ml agate ball mill jar.

[0123] XRD analysis confirmed that the reaction product was α-NaLuF4:Tb.

[0124] Example 26 The only difference from Example 17 is step (1): (1) Add 1.4348 g of lutetium chloride, 0.2240 g of terbium carbonate and 1.0078 g of sodium fluoride to a 250 ml agate ball mill jar.

[0125] XRD analysis confirmed that the reaction product was α-NaLuF4:Tb.

[0126] Example 27 The only difference from Example 17 is step (1): (1) Add 2.3917 g of lutetium nitrate, 0.2240 g of terbium carbonate, 1.0078 g of sodium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar.

[0127] XRD analysis confirmed that the reaction product was β-NaLuF4:Tb.

[0128] Example 28 The only difference from Example 17 is step (1): (1) Add 1.4348 g of lutetium chloride, 0.2568 g of terbium chloride, 1.0078 g of sodium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar.

[0129] XRD analysis confirmed that the reaction products were α-NaLuF4:Tb and β-NaLuF4:Tb.

[0130] Example 29 The only difference from Example 17 is step (1): (1) Add 1.4348 g of lutetium chloride, 0.2568 g of terbium chloride, 1.3944 g of potassium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar.

[0131] XRD analysis confirmed that the reaction product was α-KLuF4:Tb.

[0132] Example 30 The only difference from Example 17 is step (1): (1) Add 1.4348 g of lutetium chloride, 0.2568 g of terbium chloride, 3.6456 g of cesium fluoride and 10 ml of deionized water to a 250 ml agate ball mill jar.

[0133] XRD analysis confirmed that the reaction product was α-CsLu2F7:Tb.

[0134] Comparative Example 1 The difference from Example 1 lies in step (3): (3) After sealing the ball mill jar, fix it on the planetary ball mill, set the ball mill speed to 150 revolutions per minute, stop for 10 minutes every 60 minutes for intermittent ball milling, the ball milling reaction time is 40 hours, and the total running time is 46 hours and 40 minutes.

[0135] Comparative Example 2 The difference from Example 2 lies in step (3): (3) After sealing the ball mill jar, fix it on the planetary ball mill, set the ball mill speed to 580 revolutions per minute, stop for 10 minutes every 60 minutes for intermittent ball milling, the ball milling reaction time is 10 hours, and the total running time is 11 hours and 40 minutes.

[0136] Comparative Example 3 The difference from Example 3 lies in step (3): (3) After sealing the ball mill jar, fix it on the planetary ball mill, set the ball mill speed to 580 revolutions per minute, stop for 10 minutes every 60 minutes for intermittent ball milling, the ball milling reaction time is 80 hours, and the total running time is 93 hours and 20 minutes.

[0137] Comparative Example 4 The difference from Example 5 lies in step (4): (3) Take out the ball mill jar and fix it on the planetary ball mill. Set the ball mill speed to 150 revolutions per minute. Stop the ball mill for 10 minutes every 60 minutes for intermittent ball milling. The ball milling reaction time is 60 hours and the total running time is 70 hours.

[0138] Experimental conclusion: The XRD patterns of the products obtained in Examples 1 to 4 are as follows: Figure 1 As shown, the XRD patterns of the products obtained in Examples 5 to 16 are as follows. Figure 2 , Figure 3 and Figure 4 As shown, the XRD patterns of the products obtained in Examples 17 to 30 are as follows. Figure 5 , Figure 7 and Figure 8 As shown in the figures, it can be confirmed that rare earth trifluorides can be obtained in Examples 1 to 16, and composite rare earth fluorides can be obtained in Examples 17 to 30. The methods are simple, the operation is controllable, and the cycle is short. The fluorescence luminescence phenomena of the composite rare earth fluorides prepared in Examples 17 to 24 under 365nm ultraviolet light excitation are shown in the figures. Figure 6 As shown.

[0139] The XRD results of the products obtained in Comparative Examples 1, 2, 3, and 4 are as follows: Figure 9 As shown. From Figure 9 It can be seen from this: Compared with Example 1, under the same ball milling reaction time, the ball milling speed in Comparative Example 1 was too low, and the XRD of the final product showed a large number of impurity peaks, indicating that the product was impure and contained unreacted raw materials and impurities.

[0140] Compared with Example 2, under the same ball milling speed, the ball milling reaction time in Comparative Example 2 was too short, and the XRD of the final product showed a large number of impurity peaks, indicating that the product was impure and contained unreacted raw materials and impurities.

[0141] Compared with Example 3, under the same ball milling speed, the ball milling reaction time in Comparative Example 3 was too long, and the XRD of the final product had impurity peaks at about 25 degrees and 45 degrees, indicating that the product was impure and contained impurities.

[0142] Compared with Example 5, the ball milling speed was reduced in Comparative Example 4. Although the ball milling reaction time was increased, the XRD peak shape of the final product did not correspond one-to-one with the XRD peak shapes of the standard sample and the sample of Example 5, indicating that the corresponding product was not obtained or that impurities were present in the product.

[0143] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing rare earth fluorides, comprising the following steps: Rare earth raw materials are mixed with fluorinating agents and reacted under ball milling conditions, followed by an optional calcination process to obtain rare earth fluorides.

2. The preparation method according to claim 1, characterized in that, The rare earth raw materials include one or more of rare earth oxides, rare earth carbonates, rare earth hydroxides, rare earth hydrochlorides, rare earth sulfates, and rare earth nitrates; and / or The fluorinating agent includes ammonium fluoride and / or alkali metal fluorides, preferably one or more of ammonium fluoride, potassium fluoride, sodium fluoride, and cesium fluoride; and / or The rare earth elements include one or more combinations of lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium, and / or The rare earth fluoride is a rare earth trifluoride or a composite rare earth fluoride, wherein the composite rare earth fluoride is AB2F7, AB2F7:C, ABF4 or ABF4:C, where A represents ammonium ion or alkali metal ion, B represents the first rare earth metal ion, C represents the second rare earth metal ion, and F represents fluoride ion.

3. The preparation method according to claim 1 or 2, characterized in that, The molar ratio of the rare earth raw material to the fluorinating agent is 1:(3.5~12).

4. The preparation method according to any one of claims 1-3, characterized in that, The ball milling is carried out in the presence of ball milling media and ball milling solvent; Preferably, the material of the ball milling media is agate, zirconium oxide, or silicon nitride. Preferably, the grinding media is selected from one or more combinations of grinding balls with a diameter of 6 to 20 mm; Preferably, the mass of the ball milling media is 1 to 20 times the total mass of the rare earth raw materials and fluorinating reagents; Preferably, the ball milling solvent includes at least one of water and C1-C6 alcohol solvents, more preferably water and / or ethanol; Preferably, the ratio of the total mass of the rare earth raw material and the fluorinating reagent to the volume of the ball milling solvent is (0.3~2):1g / mL.

5. The preparation method according to any one of claims 1-4, characterized in that, The ball mill rotates at a speed of 200-800 rpm, preferably 500-800 rpm; and / or The reaction was carried out in a ball mill; Preferably, the grinding jar of the ball mill is made of agate; Preferably, the volume of the ball milling solvent is 1-10% of the volume of the ball milling jar, more preferably 2-5%.

6. The preparation method according to any one of claims 1-5, characterized in that, The ball milling is an intermittent ball milling, and / or the ball milling time is 20 to 60 hours; and / or the reaction temperature is 15 to 40°C; and / or the reaction time is 20 to 80 hours.

7. The preparation method according to any one of claims 1-6, characterized in that, The calcination temperature is 300~500℃; And / or, The calcination time is 8-12 hours; and / or The calcination is carried out in a protective atmosphere, preferably nitrogen, helium, or argon; and / or The method further includes the steps of washing and drying the reaction product after the reaction is completed; preferably, the solvent used for washing includes at least one of water and C1-C6 alcohol solvents, more preferably water and / or ethanol; preferably, the drying temperature is 30~100℃.

8. The preparation method according to any one of claims 1-7, characterized in that, The rare earth element is selected from any one of samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium, and the preparation method includes: The rare earth raw material is mixed with ammonium fluoride and reacted under ball milling conditions. The reaction product is then calcined to obtain rare earth trifluoride. Preferably, both the ball milling and calcination are carried out in a protective atmosphere; More preferably, the protective atmosphere includes at least one of nitrogen, helium, and argon.

9. The method according to any one of claims 1-7, characterized in that, The rare earth element is selected from any one of lanthanum, cerium, praseodymium, and neodymium. The preparation method includes: mixing the rare earth raw material with ammonium fluoride and reacting it under ball milling conditions to obtain rare earth trifluoride.

10. The preparation method according to any one of claims 1-7, characterized in that, The rare earth element is selected from any one or a combination of two of terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and yttrium. The preparation method includes: mixing the rare earth raw material with the fluorinating reagent and reacting them under ball milling conditions to obtain a composite rare earth fluoride.

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