阅读说明：本技术 一种利用稀土氯化物蒸汽焙解制备稀土氧化物粉的方法 (Method for preparing rare earth oxide powder by utilizing steam roasting of rare earth chloride ) 是由 杨少波 李玉虎 叶纪龙 吴海洋 赵德森 于 2021-10-27 设计创作，主要内容包括：本发明涉及一种利用稀土氯化物蒸汽焙解制备稀土氧化物粉的方法,步骤包括：先将稀土氯化物脱水制备焙解前驱体,然后将焙解前驱体在水蒸气气氛中焙烧,即可获得高纯度的稀土氧化物粉,并产出盐酸副产品,本发明具有工艺简单、无“三废排放”,所得稀土氧化物粉纯度高、粒度细等优点,具有良好的工业化应用前景。(The invention relates to a method for preparing rare earth oxide powder by utilizing steam roasting of rare earth chloride, which comprises the following steps: the method comprises the steps of dehydrating the rare earth chloride to prepare a roasting precursor, and roasting the roasting precursor in a steam atmosphere to obtain high-purity rare earth oxide powder and produce hydrochloric acid byproducts.)

1. A method for preparing rare earth oxide powder by utilizing steam roasting of rare earth chloride is characterized by comprising the following steps: the rare earth chloride is dehydrated to prepare a roasting precursor, then the roasting precursor is roasted in a water vapor atmosphere to obtain high-purity rare earth oxide powder, and a hydrochloric acid byproduct is produced by absorption treatment of tail gas generated by roasting.

2. The method for preparing rare earth oxide powder by using steam roasting of rare earth chloride as claimed in claim 1, wherein the method comprises the following steps: the roasting precursor is prepared by dehydrating rare earth chloride under the negative pressure condition at the temperature of 150-300 ℃, and is roasted in the steam atmosphere at the temperature of 500-1200 ℃.

3. The method for preparing rare earth oxide powder by steam roasting of rare earth chloride according to claim 2, wherein the method comprises the following steps: the negative pressure is less than or equal to-5 kPa, and the molar ratio of the crystal water to the chlorine in the roasting precursor is not less than 0.5:1 and not more than 1.5: 1.

4. The method for preparing rare earth oxide powder by steam roasting of rare earth chloride according to claim 2, wherein the method comprises the following steps: and blowing wet carrier gas into the roasting precursor in a water vapor atmosphere, wherein the flow rate of the wet carrier gas is more than 5L/min and less than 40L/min, and the humidity of the wet carrier gas is more than 50%.

5. The method for preparing rare earth oxide powder by steam roasting of rare earth chloride according to claim 4, wherein: the wet carrier gas is wet pure gas or mixed gas.

6. The method for preparing rare earth oxide powder by steam roasting of rare earth chloride according to claim 2, wherein the method comprises the following steps: the process of preparing the roasting precursor by dehydrating the rare earth chloride and the process of roasting the roasting precursor in the steam atmosphere are carried out in the same reactor.

7. The method for preparing rare earth oxide powder by steam roasting of rare earth chloride according to claim 2, wherein the method comprises the following steps: and (3) carrying out three-stage countercurrent absorption treatment on tail gas generated by roasting the roasted precursor in a water vapor atmosphere to obtain a hydrochloric acid byproduct.

8. The method for preparing rare earth oxide powder by using steam roasting of rare earth chloride as claimed in claim 1, wherein the method comprises the following steps: the chlorine content in the rare earth oxide powder is lower than 50ppm, and the total content of the rare earth is more than 99.5%.

Technical Field

The invention belongs to the field of powder material preparation, relates to a method for preparing rare earth oxide powder by utilizing rare earth chloride steam roasting, and particularly relates to a preparation method of high-purity rare earth oxide powder.

Background

Rare earth is widely used in the fields of petroleum, chemical industry, metallurgy, textile, ceramics, glass, permanent magnet materials and the like due to the special physicochemical properties of the rare earth, and is considered as a 'vitamin' in the high and new technical field. The rare earth nano oxide is the most important application form of rare earth elements, so the synthesis and preparation thereof become research hotspots in academia and industry. Although rare earth is an advantageous resource in China, most rare earth oxide products provided in China are primary products, the quality is not high, the additional value is not high, and in addition, the traditional rare earth oxide preparation process has the problem of large discharge amount of waste water and waste gas, so that the rare earth industry in China is in a big but weak embarrassing situation. Therefore, the research on the preparation process of the high-quality green rare earth oxide is of great significance.

At present, the industry mainly adopts a precipitation-calcination process to produce rare earth oxide, the process is simple, but the process is longer, the discharge amount of waste water is large, the energy consumption is higher, and particularly, the quality of the product obtained by the process is poor, the problems of coarse granularity, wider distribution and higher impurity content exist, so the product competitiveness is not strong, and the added value is not high. In order to realize the short-process green preparation of the rare earth oxide, researchers propose a new process for preparing the rare earth oxide by a flame combustion method, the rare earth oxide obtained by the process has fine granularity and high purity, but the used raw materials are rare earth organic compounds or rare earth nitrates, the sources of the materials are few, the cost is high, and the process has poor technical and economic indexes and is difficult to be industrially applied. In addition, technicians develop new processes such as a hydrothermal precipitation method, a micro-emulsion method, a sol-gel method, a flame combustion method and the like, and although the processes have various characteristics, the processes do not have breakthrough progress and mostly stay in a laboratory research stage.

Therefore, aiming at the research and development of the preparation process of the high-quality rare earth oxide, a large amount of work is carried out by scientific researchers, and some progress is made, but the problems of poor product quality and serious environmental pollution are not completely solved by the novel processes and novel methods at present, so that the rare earth industry bears great environmental protection pressure in China, and the development of a green rare earth oxide production technology is urgently needed in the industry.

Disclosure of Invention

Aiming at the defects of long process, heavy pollution and poor quality of the obtained rare earth oxide in the prior art, the invention provides a method for preparing rare earth oxide powder by roasting rare earth chloride steam.

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

a method for preparing rare earth oxide powder by utilizing steam roasting of rare earth chloride comprises the following steps: the rare earth chloride is dehydrated to prepare a roasting precursor, then the roasting precursor is roasted in a water vapor atmosphere to obtain high-purity rare earth oxide powder, and a hydrochloric acid byproduct is produced by absorption treatment of tail gas generated by roasting.

The roasting precursor is prepared by dehydrating rare earth chloride under the negative pressure condition at the temperature of 150-300 ℃, and is roasted in the steam atmosphere at the temperature of 500-1200 ℃.

The negative pressure is less than or equal to-5 kPa, and the molar ratio of the crystal water to the chlorine in the roasting precursor is not less than 0.5:1 and not more than 1.5: 1.

And blowing wet carrier gas into the roasting precursor in a water vapor atmosphere, wherein the flow rate of the wet carrier gas is more than 5L/min and less than 40L/min, and the humidity of the wet carrier gas is more than 50%.

The wet carrier gas is wet pure gas or mixed gas.

The process of preparing the roasting precursor by dehydrating the rare earth chloride and the process of roasting the roasting precursor in the steam atmosphere are carried out in the same reactor.

And (3) carrying out three-stage countercurrent absorption treatment on tail gas generated by roasting the roasted precursor in a water vapor atmosphere to obtain a hydrochloric acid byproduct.

The chlorine content in the rare earth oxide powder is lower than 50ppm, and the total content of the rare earth is more than 99.5%.

Compared with the prior art, the invention takes the rare earth chloride as the raw material, prepares the torrefaction precursor by dehydration of the rare earth chloride, strengthens the reaction by introducing water vapor, realizes complete pyrolysis of the rare earth chloride, obtains high-quality rare earth chloride, and obtains hydrochloric acid by-products by absorbing and treating tail gas generated by roasting, thereby avoiding the generation of high-salt wastewater.

(1) The technical scheme of the invention has the advantages of simple process, short flow and easy operation.

(2) According to the technical scheme, in the preparation process of the rare earth oxide powder, except rare earth chloride, no other chemical agent is consumed, so that the problem of impurity introduction does not exist, and the purity of the obtained rare earth oxide powder is high.

(3) The rare earth oxide powder obtained by the invention has regular shape, fine granularity, high product quality and high added value of products.

(4) The invention has the advantages of environment friendliness, high resource utilization rate and no generation of waste gas, waste water and waste residue.

Detailed Description

The invention discloses a method for preparing rare earth oxide powder by utilizing steam roasting of rare earth chloride, which comprises the following steps: the rare earth chloride is dehydrated to prepare a roasting precursor, then the roasting precursor is roasted in a water vapor atmosphere to obtain high-purity rare earth oxide powder, and a hydrochloric acid byproduct is produced by absorption treatment of tail gas generated by roasting.

And the roasting precursor is prepared by dehydrating rare earth chloride under the negative pressure condition and at the temperature of 150-300 ℃, and is roasted in the steam atmosphere at the temperature of 500-1200 ℃.

And then, the negative pressure condition is that the pressure is less than or equal to-5 kPa, and the molar ratio of the crystal water to the chlorine in the roasting precursor is not less than 0.5:1 and not more than 1.5: 1.

Secondly, blowing wet carrier gas into the roasting precursor in the roasting process of the steam atmosphere, wherein the flow rate of the wet carrier gas is more than 5L/min and less than 40L/min, and the humidity of the wet carrier gas is more than 50%.

Further, the wet carrier gas is wet pure gas or mixed gas; wherein, the pure gas can be oxygen or nitrogen, and the mixed gas can be air.

In addition, for convenience of operation, the process of preparing the torrefaction precursor by dehydrating the rare earth chloride and the process of calcining the torrefaction precursor in the water vapor atmosphere may be performed in the same reactor, but not limited thereto, and the process of preparing the torrefaction precursor by dehydrating the rare earth chloride and the process of calcining the torrefaction precursor in the water vapor atmosphere may also be performed separately.

Further, tail gas generated by roasting the roasting precursor in a water vapor atmosphere can be subjected to three-stage countercurrent absorption treatment to obtain a hydrochloric acid byproduct.

In addition, the chlorine content in the rare earth oxide powder is lower than 50ppm, and the total content of the rare earth is more than 99.5%.

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 by utilizing steam roasting of rare earth chloride comprises the following steps:

6.4kg of cerium chloride (CeCl) was charged into the pyrolysis furnace₃·7H₂O, AR), controlling the pressure in the furnace to be-25 to-20 KPa by using a vacuum pump, then heating to 180 ℃, preserving heat for 2.5 hours, and measuring that the precursor band for preparing the torrefaction precursor by dehydrating the cerium chloride is 3.5H₂O, the molar ratio of crystal water to chlorine in the preparation of the calcination precursor by dehydrating cerium chloride is 0.6: 1, then closing the vacuum pump, opening the pressure relief valve, and continuing to heat to 650 ℃. And introducing wet air after the temperature reaches 650 ℃, adjusting the air humidity by using a humidifier, wherein the air flow is 6L/min, and the air humidity is 87%, so that the roasting precursor is roasted in a water vapor atmosphere. And maintaining the above conditions to continue the reaction for 3.5h, then cooling and collecting the product. The product is analyzed, and the obtained product is single cubic phase CeO₂Powder with spherical particles of 0.42 μm average diameter and particle size distributionRelatively narrow, CeO₂The chlorine content in the powder is 42ppm, the total content of the rare earth is more than 99.5 percent, and the product purity is higher; and carrying out three-stage countercurrent absorption treatment on tail gas generated by roasting the roasting precursor in a water vapor atmosphere to obtain a hydrochloric acid byproduct.

Comparative example 1

6.4kg of cerium chloride (CeCl) was charged into the pyrolysis furnace₃·7H₂O, AR), heating to 180 ℃ and keeping the temperature for 2.5 h. Then the temperature was further raised to 650 ℃. When the temperature reaches 650 ℃, introducing wet air, and adjusting the air humidity by using a humidifier, wherein the air flow is 6L/min, and the air humidity is 87%. And maintaining the above conditions to continue the reaction for 3.5h, then cooling and collecting the product. The product is analyzed, and the obtained product contains CeO except for cubic phase₂In addition, a certain amount of CeClO exists, the average grain diameter is 3.87 mu m, the grain size distribution is wide, the total amount of the rare earth is 92.8 percent, the product purity is low, and the product index cannot be met.

The difference between the comparative example 1 and the example 1 is that in the example 1, the torrefaction precursor of the invention is prepared by dehydrating the rare earth chloride under the negative pressure condition, while the torrefaction precursor in the comparative example 1 is prepared by dehydrating the rare earth chloride under the normal pressure, but the difference between the rare earth chloride and the torrefaction precursor is more remarkable. Under the negative pressure condition, the crystal water can be removed to the required index (the mol ratio of the crystal water to the chlorine in the roasting precursor is not lower than 0.5:1 and not higher than 1.5: 1) at a lower temperature, and the low-temperature decomposition of the cerium chloride can be avoided under the negative pressure atmosphere, so that the consistency of the cerium chloride during roasting in the steam atmosphere can be ensured. Therefore, partial decomposition and sintering of cerium chloride can be avoided by using negative pressure, thereby being beneficial to obtaining high-purity and uniform-particle-size CeO₂And (5) producing the product.

Example 2:

a method for preparing rare earth oxide powder by utilizing steam roasting of rare earth chloride comprises the following steps:

6.4kg of yttrium chloride (YCl) was added to the pyrolysis furnace₃·6H₂O, AR), controlling the pressure in the furnace to be-40 to-45 KPa by using a vacuum pump, then heating to 240 ℃, and preserving heat for 3.5 hours. Measuring the preparation of the precursor of the roasting decomposition by dehydrating the yttrium chlorideBody girdle 3.5H₂O, dehydrating yttrium chloride to prepare a calcination precursor, wherein the molar ratio of crystal water to chlorine in the calcination precursor is 0.6: 1, then closing the vacuum pump, opening the pressure relief valve, and continuously heating to 800 ℃. And (3) after the temperature reaches 800 ℃, introducing wet oxygen, adjusting the humidity of the oxygen by using a humidifier, wherein the flow rate of the oxygen is 9L/min, and the humidity of the oxygen is 92% so as to roast the roasting precursor in a water vapor atmosphere. And maintaining the above conditions to continue the reaction for 4.5h, then cooling and collecting the product. The product is analyzed, and the obtained product is Y with single cubic phase₂O₃The powder is in the shape of spheroidal particles, the average particle size is 1.25 mu m, the particle size distribution is narrow, and Y is₂O₃The chlorine content in the powder is 39ppm, the total content of the rare earth is more than 99.5 percent, and the product purity is higher; and carrying out three-stage countercurrent absorption treatment on tail gas generated by roasting the roasting precursor in a water vapor atmosphere to obtain a hydrochloric acid byproduct.

Comparative example 2

6.4kg of yttrium chloride (YCl 3 & 6H2O, AR) was added to the pyrolysis furnace and then heated to 800 ℃. When the temperature reaches 800 ℃, introducing wet oxygen, and adjusting the humidity of the oxygen by using a humidifier, wherein the flow rate of the oxygen is 9L/min, and the humidity of the oxygen is 92%. And maintaining the above conditions to continue the reaction for 4.5h, then cooling and collecting the product. The product is analyzed, and the obtained product has Y except cubic phase₂O₃A certain amount of YClO is also present, indicating that the pyrolysis reaction is not fully carried out. The average grain diameter of the obtained product is 7.84 mu m, the grain diameter distribution is wider, the total amount of the rare earth is more than 90.7 percent, and the product purity is lower.

Comparative example 2 is different from example 2 in that in example 2, a two-stage operation system in which a rare earth chloride is dehydrated to prepare a torrefaction precursor and the torrefaction precursor is calcined in a steam atmosphere is adopted, whereas in comparative example 2, the composition and content of a reaction product are significantly different due to the difference that one-stage calcination system is directly adopted. The yttrium chloride is subjected to dehydration and decomposition reaction in sequence in a high-temperature field, when the two-stage operation of dehydrating the rare earth chloride to prepare the torrefaction precursor and then roasting the torrefaction precursor in the steam atmosphere is adopted, the dehydration and decomposition reaction are carried out in sequence, and when one-stage operation is adoptedDuring the stage roasting, the dehydration and roasting reactions are overlapped, so that the consistency of the product is poor, and CeO is formed in the early stage₂The activity is too high, the sintering is easy, the decomposition of yttrium chloride is inhibited, and the pyrolysis reaction is difficult to be carried out completely.

Example 3:

a method for preparing rare earth oxide powder by utilizing steam roasting of rare earth chloride comprises the following steps:

6.4kg of ytterbium chloride (YbCl) was charged into the pyrolysis furnace₃·6H₂O, AR), controlling the pressure in the furnace to be-40 to-45 KPa by using a vacuum pump, then heating to 270 ℃, and preserving heat for 3 hours. Measuring that the precursor band of the roasting decomposition prepared by the dehydration of ytterbium chloride is 3.5H₂O, dehydrating ytterbium chloride to prepare a calcination precursor, wherein the molar ratio of crystal water to chlorine in the calcination precursor is 0.6: 1, then closing the vacuum pump, opening the pressure relief valve, and continuously heating to 850 ℃. When the temperature reaches 850 ℃, introducing wet oxygen-nitrogen mixed gas (the mass ratio of oxygen to nitrogen is 0.65: 0.35), adjusting the humidity of the oxygen-nitrogen mixed gas by a humidifier, wherein the flow rate of the mixed gas is 8L/min, and the humidity of the oxygen-nitrogen mixed gas is 75% so as to roast the roasting precursor in a water vapor atmosphere. And (5) maintaining the above conditions to continue the reaction for 5 hours, then cooling and collecting the product. The product is analyzed, and the obtained product is single cubic phase Yb₂O3 powder in the form of spherical particles with average diameter of 0.67 microns and narrow distribution of Yb₂The content of chlorine in O3 powder is 36ppm, the total content of rare earth is more than 99.5%, and the product purity is high; and carrying out three-stage countercurrent absorption treatment on tail gas generated by roasting the roasting precursor in a water vapor atmosphere to obtain a hydrochloric acid byproduct.

Example 4:

a method for preparing rare earth oxide powder by utilizing steam roasting of rare earth chloride comprises the following steps:

6.4kg of erbium chloride (ErCl) was charged into the pyrolysis furnace₃·6H₂O, AR), controlling the pressure in the furnace to be-30 to-35 KPa by using a vacuum pump, then heating to 280 ℃, and preserving heat for 2 hours. Measuring the 3H of the precursor band for preparing the torrefaction by dehydrating the erbium chloride₂O, the molar ratio of crystal water to chlorine in the preparation of the calcination precursor by erbium chloride dehydration is 0.5:1, thenThen the vacuum pump is closed, the pressure relief valve is opened, and the temperature is continuously raised to 800 ℃. And (3) after the temperature reaches 800 ℃, introducing wet nitrogen, adjusting the humidity of the nitrogen by using a humidifier, wherein the flow rate of the nitrogen is 6L/min, and the humidity of the nitrogen is 82% so as to roast the roasting precursor in a water vapor atmosphere. And maintaining the above conditions to continue the reaction for 3.5h, then cooling and collecting the product. The analysis of the sample shows that the obtained product is Er with single cubic phase₂O₃The product has the advantages of spherical-like particle appearance, average particle size of 1.69 mu m, narrow particle size distribution, rare earth chloride content of 32ppm, total rare earth content of more than 99.5 percent and high product purity.

Example 5:

a method for preparing rare earth oxide powder by utilizing steam roasting of rare earth chloride comprises the following steps:

6.4kg of cerium chloride (CeCl) was charged into the pyrolysis furnace₃·7H₂O, AR), controlling the pressure in the furnace to be-10 to-15 KPa by using a vacuum pump, then heating to 160 ℃, and preserving heat for 4.5 hours. Measuring the 3H of the precursor band for preparing the torrefaction by dehydrating the cerium chloride₂O, the molar ratio of crystal water to chlorine in the preparation of the calcination precursor by dehydrating cerium chloride is 0.5:1, then closing the vacuum pump, opening the pressure relief valve, and continuing to heat to 600 ℃. And after the temperature reaches 600 ℃, introducing wet oxygen, adjusting the humidity of the oxygen by using a humidifier, wherein the flow rate of the oxygen is 5L/min, and the humidity of the oxygen is 6.5% so as to roast the roasting precursor in a water vapor atmosphere. And keeping the above conditions to continue the reaction for 4 hours, then cooling and collecting the product. The product is analyzed, and the obtained product is single cubic phase CeO₂Powder with spherical particle shape of 0.64 μm average particle size and narrow particle size distribution₂The chlorine content in the powder is 32ppm, the total content of the rare earth is more than 99.5 percent, and the product purity is higher; and carrying out three-stage countercurrent absorption treatment on tail gas generated by roasting the roasting precursor in a water vapor atmosphere to obtain a hydrochloric acid byproduct.

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.