阅读说明：本技术 一种短流程绿色化制备稀土氧化物粉的方法 (Method for preparing rare earth oxide powder in short-process green manner ) 是由 李来超 吴海洋 赵德森 叶纪龙 杨少波 于 2021-10-27 设计创作，主要内容包括：本发明涉及一种短流程绿色化制备稀土氧化物粉的方法,步骤包括：先采用喷雾干燥法对稀土氯化物溶液进行处理,制备热解前驱体；然后将所得热解前驱体进行焙烧热解反应,使热解前驱体分解为相应的稀土氧化物粉,所产生的尾气经吸收后得到盐酸产品,本发明方法具有工艺简单、无“三废”排放、能耗低、资源利用率高等优点,因而具有良好的工业化应用前景。(The invention relates to a method for preparing rare earth oxide powder in a short-process green way, which comprises the following steps: firstly, processing a rare earth chloride solution by adopting a spray drying method to prepare a pyrolysis precursor; and then, carrying out roasting pyrolysis reaction on the obtained pyrolysis precursor to decompose the pyrolysis precursor into corresponding rare earth oxide powder, and absorbing the generated tail gas to obtain a hydrochloric acid product.)

1. A method for preparing rare earth oxide powder in a short-process green way is characterized by comprising the following steps: firstly, processing a rare earth chloride solution by adopting a spray drying method to prepare a pyrolysis precursor; and then, carrying out roasting pyrolysis reaction on the obtained pyrolysis precursor to decompose the pyrolysis precursor into corresponding rare earth oxide powder, and absorbing the generated tail gas to obtain a hydrochloric acid product.

2. The method for preparing rare earth oxide powder by short-process greening according to claim 1, wherein the method comprises the following steps: the rare earth chloride solution is spray-dried at the temperature of 200-300 ℃, and the pyrolysis precursor is roasted and pyrolyzed at the temperature of 600-1200 ℃.

3. The method for preparing rare earth oxide powder by short-process greening according to claim 2, wherein: the molar ratio of crystal water to chlorine in the pyrolysis precursor is not higher than 2.5: 1.

4. The method for preparing rare earth oxide powder by short-process greening according to claim 2, wherein: the particle size of the pyrolysis precursor is not more than 45 μm.

5. The method for preparing rare earth oxide powder by short-process greening according to claim 2, wherein: air or oxygen is introduced into the roasting pyrolysis reaction, and the humidity of the gas in the roasting pyrolysis reaction is more than 70%.

6. The method for preparing rare earth oxide powder by short-process greening according to claim 2, wherein: the rare earth chloride solution is prepared by dissolving rare earth oxide; and (4) performing heat exchange treatment on the tail gas generated in the spray drying process and the rare earth chloride solution to obtain condensed water, and recycling the condensed water to the rare earth chloride dissolving process.

7. The method for preparing rare earth oxide powder by short-process greening according to claim 2, wherein: the rare earth oxide powder is single rare earth oxide powder or rare earth composite oxide powder.

8. The method for preparing rare earth oxide powder by short-process greening according to claim 1, wherein the method comprises the following steps: the chlorine content in the rare earth oxide powder is lower than 500ppm, and the total content of the rare earth is more than 99.5%.

9. The method for preparing rare earth oxide powder by short-process greening according to claim 1, wherein the method comprises the following steps: the spray drying method is realized by using a spray dryer.

10. The method for preparing rare earth oxide powder by short-process greening according to claim 9, wherein: the inlet air temperature of the spray dryer is 200-300 ℃, and the outlet air temperature of the spray dryer is 100-150 ℃.

Technical Field

The invention belongs to the field of powder material preparation, relates to a short-process green preparation method of rare earth oxide powder, and particularly relates to a preparation method of high-purity rare earth oxide powder.

Background

At present, the rare earth oxide powder generally adopts a precipitation-calcination process, namely, carbonate or oxalic acid is used as a precipitator, and rare earth is precipitated from a solution under certain process conditions to obtain a rare earth precipitate; then the rare earth precipitate is calcined at a certain temperature, and the corresponding rare earth oxide can be obtained. The method has simple process and easy operation, but the obtained product has irregular appearance, thicker granularity, poorer purity, longer production flow and larger amount of waste water, thereby having higher cost and serious environmental pollution. In order to improve the situation, technicians develop a series of new methods for producing rare earth oxides, such as hydrothermal precipitation method, microemulsion method, sol-gel method and the like, wherein flame combustion method and spray pyrolysis method are most representative, however, the flame combustion method needs to use rare earth organic compounds as raw materials, the raw material source is narrow, the cost is high, the energy consumption of the spray pyrolysis method is high, and the rare earth compounds are difficult to be thoroughly pyrolyzed, so that the product has high impurity phase content and low purity. Therefore, although researchers have developed a large number of novel processes for preparing rare earth oxide powders with various characteristics, these methods have not completely solved the problems so far, and most of them still remain in the laboratory research stage.

Therefore, the conventional precipitation-roasting process is still adopted to produce the rare earth oxide powder, so that the technical and economic indexes of enterprises are poor, clean production is difficult to realize, and huge economic and environmental protection pressure is borne.

Disclosure of Invention

Aiming at the problems of high cost, poor quality and heavy pollution of the traditional precipitation-roasting preparation of rare earth oxide powder, the invention provides a short-process green preparation method of rare earth oxide powder.

In order to achieve the technical purpose, the invention adopts the following technical scheme:

a method for preparing rare earth oxide powder in a short-flow green way comprises the following steps: firstly, processing a rare earth chloride solution by adopting a spray drying method to prepare a pyrolysis precursor; and then, carrying out roasting pyrolysis reaction on the obtained pyrolysis precursor to decompose the pyrolysis precursor into corresponding rare earth oxide powder, and absorbing the generated tail gas to obtain a hydrochloric acid product.

The rare earth chloride solution is spray-dried at the temperature of 200-300 ℃, and the pyrolysis precursor is roasted and pyrolyzed at the temperature of 600-1200 ℃.

The molar ratio of crystal water to chlorine in the pyrolysis precursor is not higher than 2.5: 1.

The particle size of the pyrolysis precursor is not more than 45 μm.

Air or oxygen is introduced into the roasting pyrolysis reaction, and the humidity of the gas in the roasting pyrolysis reaction is more than 70%.

The rare earth chloride solution is prepared by dissolving rare earth oxide; and (4) performing heat exchange treatment on the tail gas generated in the spray drying process and the rare earth chloride solution to obtain condensed water, and recycling the condensed water to the rare earth chloride dissolving process.

The rare earth oxide powder is single rare earth oxide powder or rare earth composite oxide powder.

The chlorine content in the rare earth oxide powder is lower than 500ppm, and the total content of the rare earth is more than 99.5%.

The spray drying method is realized by using a spray dryer.

The inlet air temperature of the spray dryer is 200-300 ℃, and the outlet air temperature of the spray dryer is 100-150 ℃.

After the technical scheme is adopted, compared with the prior art, the method adopts a spray drying method to treat the rare earth chloride solution to prepare a pyrolysis precursor; then, the obtained pyrolysis precursor is subjected to roasting pyrolysis reaction, so that the pyrolysis precursor is decomposed into corresponding oxides, and the generated tail gas is absorbed to obtain a high-concentration hydrochloric acid product, so that the preparation of high-quality rare earth oxide powder is realized, a high-concentration inorganic acid product can be obtained, and the problem of discharge of wastewater is completely eradicated, so that the high-value utilization and green processing of rare earth resources are realized, and the method has the following advantages:

(1) the method has the advantages of simple process, no special equipment requirement and easy realization.

(2) The invention has wide raw material source, short production flow, high quality of the obtained rare earth oxide powder and better technical and economic indexes.

(3) The invention has high resource utilization rate, not only fully utilizes the rare earth, but also realizes resource utilization of chloride ions.

(4) The invention is environment-friendly, and does not generate waste gas, waste water and waste residue.

Detailed Description

The invention discloses a method for preparing rare earth oxide powder in a short-process green way, which comprises the following steps: firstly, processing a rare earth chloride solution by adopting a spray drying method to prepare a pyrolysis precursor; and then, carrying out roasting pyrolysis reaction on the obtained pyrolysis precursor to decompose the pyrolysis precursor into corresponding rare earth oxide powder, and absorbing the generated tail gas to obtain a hydrochloric acid product.

And the rare earth chloride solution is spray-dried at the temperature of 200-300 ℃, and the pyrolysis precursor is roasted and pyrolyzed at the temperature of 600-1200 ℃.

Then, the molar ratio of crystal water to chlorine in the pyrolysis precursor is not higher than 2.5: 1.

Wherein the particle size of the pyrolysis precursor is not more than 45 μm.

In addition, air or oxygen is introduced into the roasting pyrolysis reaction, and the humidity of the gas in the roasting pyrolysis reaction is more than 70%.

Further, the rare earth chloride solution is prepared by dissolving rare earth oxide; and (4) performing heat exchange treatment on the tail gas generated in the spray drying process and the rare earth chloride solution to obtain condensed water, and recycling the condensed water to the rare earth chloride dissolving process.

And secondly, the rare earth oxide powder is single rare earth oxide powder or rare earth composite oxide powder.

In addition, the chlorine content in the rare earth oxide powder is lower than 500ppm, and the total content of the rare earth is more than 99.5%.

In the embodiment, the spray drying method is realized by using a spray dryer; the inlet air temperature of the spray dryer is 200-300 ℃, and the outlet air temperature of the spray dryer is 100-150 ℃.

In order to illustrate the above technical solutions of the present invention, the following examples are given for illustration and are not intended to limit the scope of the claims of the present invention.

Example 1:

a method for preparing rare earth oxide powder in a short-flow green way comprises the following steps:

(1) with yttrium chloride (YCl)₃·6H₂O, AR) is used as a raw material, and is prepared into 2.2M solution which is used as yttrium chloride stock solution after being filtered and refined; the yttrium chloride solution is filtered and refined to eliminate foreign matter influence possibly brought by raw materials, so that the purity of the product is not influenced.

(2) And starting a spray dryer, setting the inlet air temperature to be 240 ℃, and pumping the yttrium chloride stock solution into the spray dryer to prepare a pyrolysis precursor after preheating is finished. In the preparation process of the precursor for pyrolysis, the temperature of outlet air needs to be controlled at 110 ℃. After spray drying is finished, collecting a pyrolysis precursor, screening and grading by adopting a 325-mesh screen, removing large particles on the screen, taking undersize powder as the pyrolysis precursor, detecting the particle size of the pyrolysis precursor to be 40 mu m, and calculating the 6H carried by chloride crystals at the moment₂O water, wherein the molar ratio of the crystal water to the chlorine in the pyrolysis precursor is 2: 1.

(3) subjecting the pyrolysis precursor YCl₃·3H₂And adding O into a roasting furnace, and heating to 900 ℃ to carry out roasting pyrolysis reaction. Air is introduced in the roasting pyrolysis process, the air humidity is 75-80%, and the air flow is 5L/min. After reacting for 3h, cooling and reducing the temperature to obtain an yttrium oxide powder product with the average grain diameter of 1.12 mu m, fine granularity, narrow granularity distribution, 348ppm chlorine content, high purity and more than 99.5 percent of total rare earth.

Comparative example 1

A preparation method of rare earth oxide powder comprises the following steps: with yttrium chloride (YCl)₃·6H₂O, AR) is taken as a raw material, and the raw material is added into a roasting furnace, and the temperature is raised to 900 ℃ for roasting and pyrolysis reaction. Air is introduced in the roasting pyrolysis process, the air humidity is 75-80%, and the air flow is 5L/min. After reacting for 3 hours, cooling and obtaining the productThe yttrium oxide powder product with the average grain diameter of 6.52 mu m has coarse grain size and wider grain size distribution, the chlorine content exceeds 4185ppm, the purity is lower, and the total content of the rare earth is 97.4 percent.

Comparative example 1 differs from example 1 in that in example 1, yttrium chloride (YCl) is first spray dried₃·6H₂O) to obtain a pyrolysis precursor with a particle size of less than 45 μm and a reasonable content of water of crystallization, while yttrium chloride (YCl) is used directly in comparative example 1₃·6H₂O) as the pyrolysis feedstock, but the two make a more significant difference. In the embodiment 1, the pyrolysis precursor with better reaction activity can be obtained through spray drying, and meanwhile, the dehydration and pyrolysis can be carried out step by step, while in the direct roasting of the comparative example 1, the dehydration and pyrolysis are carried out synchronously, so that the problem of coating of a pyrolysis product on an unreacted material is easy to occur, the pyrolysis reaction is prevented from being carried out, the granularity of the product is increased, and the decomposition is incomplete.

Example 2:

a method for preparing rare earth oxide powder in a short-flow green way comprises the following steps:

(1) with cerium chloride (CeCl)₃·7H₂O, AR) as raw material, preparing into 1.8M solution, filtering, refining, and using as stock solution.

(2) And starting a spray dryer, setting the inlet air temperature to 210 ℃, and pumping the cerium chloride stock solution into the spray dryer to prepare a pyrolysis precursor after preheating is finished. In the preparation process of the precursor for pyrolysis, the temperature of outlet air needs to be controlled at 110 ℃. And after the spray drying is finished, collecting the pyrolysis precursor, screening and grading by adopting a 400-mesh screen, removing large particles on the screen, and taking undersize powder as the pyrolysis precursor. The particle size of the pyrolysis precursor was measured to be 35 μm, at which time the chloride crystal carryover was estimated to be 7H₂O water, the molar ratio of crystal water to chlorine in the pyrolysis precursor is 2.33: 1.

(3) pyrolysis precursor CeCl₃·3H₂And adding O into a roasting furnace, and heating to 650 ℃ for roasting pyrolysis reaction. Air is introduced in the roasting pyrolysis process, the air humidity is 75-80%, and the air flow is 5L/min. After reacting for 3h, cooling downAnd (3) obtaining the cerium oxide powder product with the average grain diameter of 0.62 mu m at a high temperature, wherein the cerium oxide powder product has fine grain size and narrow grain size distribution, the chlorine content is 34ppm, the purity is high, and the total content of the rare earth is more than 99.5 percent.

Comparative example 2

A preparation method of rare earth oxide powder comprises the following steps:

(1) with cerium chloride (CeCl)₃·7H₂O, AR) as raw material, preparing into 1.8M solution, filtering, refining, and using as stock solution.

(2) Starting a spray dryer, setting the inlet air temperature to be 150 ℃, pumping the cerium chloride stock solution into the spray dryer to prepare a pyrolysis precursor after preheating is finished, detecting the particle size of the pyrolysis precursor to be 60 mu m, and calculating the chloride crystal carrying 6H at the moment₂O water, wherein the molar ratio of the crystal water to the chlorine in the pyrolysis precursor is 2: 1. in the preparation process of the precursor by pyrolysis, the temperature of outlet air needs to be controlled at 90 ℃. And after the spray drying is finished, collecting the pyrolysis precursor, screening and grading by adopting a 400-mesh screen, removing large particles on the screen, and taking undersize powder as the pyrolysis precursor.

(3) Pyrolysis precursor CeCl₃·5H₂And adding O into a roasting furnace, and heating to 650 ℃ for roasting pyrolysis reaction. Air is introduced in the roasting pyrolysis process, the air humidity is 75-80%, and the air flow is 5L/min. After reacting for 3h, cooling and cooling to obtain the cerium oxide powder product with the average grain diameter of 3.62 mu m, fine granularity, narrow granularity distribution, 3114ppm chlorine content, high purity and more than 98.2 percent of total rare earth.

Comparative example 2 differs from example 2 in that the inlet and outlet air temperatures of the spray-drying in example 1 were 210 and 110 c, respectively, while the inlet and outlet air temperatures of the spray-drying in comparative example 2 were 150 and 90 c, respectively, which resulted in a significant difference in the composition and particle size of the reaction product. When the spray drying temperature is lower, dehydration is incomplete, so that dehydration reaction still exists during pyrolysis, the pyrolysis reaction consistency is poor, the sintering problem is easy to occur, and the reaction product has larger particle size and higher chlorine content.

Example 3:

a method for preparing rare earth oxide powder in a short-flow green way comprises the following steps:

(1) with ytterbium chloride (YbCl)₃·6H₂O, AR) as raw material, preparing into 2.1M solution, filtering, refining, and using as stock solution.

(2) And starting a spray dryer, setting the inlet air temperature to be 270 ℃, and pumping the ytterbium chloride stock solution into the spray dryer to prepare a pyrolysis precursor after preheating is finished. In the preparation process of the precursor by pyrolysis, the temperature of outlet air needs to be controlled at 120 ℃. And after the spray drying is finished, collecting the pyrolysis precursor, screening and grading by adopting a 325-mesh screen, removing large particles on the screen, and taking undersize powder as the pyrolysis precursor. The particle size of the pyrolysis precursor was measured to be 38 μm, at which time the chloride crystal carryover was estimated to be 6H₂O water, wherein the molar ratio of the crystal water to the chlorine in the pyrolysis precursor is 2: 1.

(3) and adding the pyrolysis precursor into a roasting furnace, and heating to 750 ℃ to carry out roasting pyrolysis reaction. Air is introduced in the roasting pyrolysis process, the air humidity is 85-90%, and the air flow is 7L/min. After 4 hours of reaction, cooling and cooling are carried out, and the ytterbium oxide powder product with the average grain diameter of 1.47 mu m can be obtained, the granularity is fine, the granularity distribution is narrow, the chlorine content is 386ppm, the purity is high, and the total content of rare earth is more than 99.5 percent.

Example 4:

a method for preparing rare earth oxide powder in a short-flow green way comprises the following steps:

(1) with samarium chloride (SmCl)₃·6H₂O, AR) as raw material, preparing into 2.0M solution, filtering, refining, and using as stock solution.

(2) And starting a spray dryer, setting the inlet air temperature to be 240 ℃, and pumping the samarium chloride stock solution into the spray dryer to prepare a pyrolysis precursor after preheating is finished. In the preparation process of the precursor for pyrolysis, the temperature of outlet air needs to be controlled at 110 ℃. And after the spray drying is finished, collecting the pyrolysis precursor, screening and grading by adopting a 400-mesh screen, removing large particles on the screen, and taking undersize powder as the pyrolysis precursor. Particle size of the pyrolysis precursor was measured to be 34 μm, and measured at this timeChloride crystals carrying 6H₂O water, wherein the molar ratio of the crystal water to the chlorine in the pyrolysis precursor is 2: 1.

(3) and adding the pyrolysis precursor into a roasting furnace, and heating to 950 ℃ for roasting pyrolysis reaction. Air is introduced in the roasting pyrolysis process, the air humidity is 85-90%, and the air flow is 9L/min. After 5h of reaction, cooling and cooling to obtain samarium oxide powder with the average particle size of 1.56 mu m, wherein the samarium oxide powder has fine particle size, narrow particle size distribution, 292 ppm of chlorine content, high purity and more than 99.5 percent of total rare earth.

Example 5:

a method for preparing rare earth oxide powder in a short-flow green way comprises the following steps:

(1) with erbium chloride (ErCl)₃·6H₂O, AR) as raw material, preparing into 2.2M solution, filtering, refining, and using as stock solution.

(2) And starting a spray dryer, setting the inlet air temperature to be 230 ℃, and pumping the erbium chloride stock solution into the spray dryer to prepare a pyrolysis precursor after preheating is finished. In the preparation process of the precursor for pyrolysis, the temperature of outlet air needs to be controlled at 130 ℃. And after the spray drying is finished, collecting a pyrolysis precursor, screening and grading by adopting a 350-mesh screen, removing large particles on the screen, and taking undersize powder as the pyrolysis precursor. The particle size of the pyrolysis precursor was measured to be 39 μm, and the crystal water in the pyrolysis precursor was then calculated to calculate the chloride crystal carry-over 6H₂Water O, in a molar ratio to chlorine of 2: 1.

(3) and adding the pyrolysis precursor into a roasting furnace, and heating to 850 ℃ for roasting pyrolysis reaction. Air is introduced in the roasting pyrolysis process, the air humidity is 80-85%, and the air flow is 8L/min. After 4 hours of reaction, the mixture is cooled and cooled to obtain an erbium oxide powder product with the average grain diameter of 1.37 mu m, the erbium oxide powder product has fine grain size and narrow grain size distribution, the chlorine content is 277ppm, the purity is higher, and the total content of rare earth is more than 99.5 percent.

Example 6:

a method for preparing rare earth oxide powder in a short-flow green way comprises the following steps:

(1) with neodymium chloride (NdCl)₃·6H₂O, AR) as raw material, preparing into 1.7M solution, filtering, refining, and using as stock solution.

(2) And starting a spray dryer, setting the inlet air temperature to be 280 ℃, and pumping the neodymium chloride stock solution into the spray dryer to prepare a pyrolysis precursor after preheating is finished. In the preparation process of the precursor by pyrolysis, the temperature of outlet air needs to be controlled at 120 ℃. And after the spray drying is finished, collecting the pyrolysis precursor, screening and grading by adopting a 500-mesh screen, removing large particles on the screen, and taking undersize powder as the pyrolysis precursor. The particle size of the pyrolysis precursor was measured to be 32 μm, at which time the chloride crystal carryover was estimated to be 6H₂O water, wherein the molar ratio of the crystal water to the chlorine in the pyrolysis precursor is 2: 1.

(3) and adding the pyrolysis precursor into a roasting furnace, and heating to 1050 ℃ to carry out baking pyrolysis reaction. Air is introduced in the roasting pyrolysis process, the air humidity is 85-90%, and the air flow is 10L/min. After 4 hours of reaction, cooling and cooling to obtain the neodymium oxide powder product with the average grain diameter of 0.88 μm, fine granularity, narrow granularity distribution, 214ppm of chlorine content, high purity and more than 99.5 percent of total rare earth.

In conclusion, compared with the prior art, the method adopts a spray drying method to treat the rare earth chloride solution to prepare the pyrolysis precursor; then, the obtained pyrolysis precursor is subjected to roasting pyrolysis reaction, so that the pyrolysis precursor is decomposed into corresponding oxides, and the generated tail gas is absorbed to obtain a high-concentration hydrochloric acid product, so that the preparation of high-quality rare earth oxide powder is realized, a high-concentration inorganic acid product can be obtained, and the problem of discharge of wastewater is completely eradicated, so that the high-value utilization and green processing of rare earth resources are realized, and the method has the following advantages:

(1) the method has the advantages of simple process, no special equipment requirement and easy realization.

(2) The invention has wide raw material source, short production flow, high quality of the obtained rare earth oxide powder and better technical and economic indexes.

(3) The invention has high resource utilization rate, not only fully utilizes the rare earth, but also realizes resource utilization of chloride ions.

(4) The invention is environment-friendly, and does not generate waste gas, waste water and waste residue.

The technical contents and technical features of the present invention have been disclosed above, and the application of the present invention is not limited to the above, for convenience of description, dysprosium nitrate is taken as an example, and the present invention can be actually applied to products such as rare earth, cobalt nickel, aluminum, etc. Those skilled in the art may make various alterations and modifications based on the disclosure of the present invention without departing from the spirit of the invention. Therefore, the scope of the present invention should not be limited to the embodiments disclosed, but includes various alternatives and modifications without departing from the present invention, which are encompassed by the claims.