阅读说明：本技术 一种纳米稀土氧化物的微波制备方法 (Microwave preparation method of nano rare earth oxide ) 是由 黄志民 黄慨 顾传君 冼学权 黄绍权 黄华林 于 2020-04-24 设计创作，主要内容包括：本发明公开了一种纳米稀土氧化物的微波制备方法,包括如下步骤,(1)表面处理：取稀土盐溶液调节pH呈碱性,加入表面助剂,得到表面处理的含稀土溶液；(2)沉淀反应：在经过表面处理的含稀土溶液中边搅拌边滴加沉淀剂,经陈化,过滤,洗涤,得到相应稀土沉淀物；(3)微波煅烧：将沉淀物放入微波反应器中进行微波加热煅烧,得到纳米稀土氧化物粉体。本发明采用微波加热煅烧的方法配合表面助剂制备得到颗粒度均匀,形貌一致,分散性好的纳米稀土氧化物。(The invention discloses a microwave preparation method of nano rare earth oxide, which comprises the following steps of (1) surface treatment: taking rare earth salt solution to adjust the pH value to be alkaline, and adding a surface auxiliary agent to obtain rare earth-containing solution for surface treatment; (2) precipitation reaction: dropwise adding a precipitant into the rare earth-containing solution subjected to surface treatment while stirring, and aging, filtering and washing to obtain a corresponding rare earth precipitate; (3) microwave calcination: and placing the precipitate into a microwave reactor for microwave heating and calcining to obtain the nano rare earth oxide powder. The invention adopts a microwave heating calcination method and surface additives to prepare the nano rare earth oxide with uniform granularity, consistent appearance and good dispersibility.)

1. A microwave preparation method of nanometer rare earth oxide is characterized in that: comprises the following steps of (a) carrying out,

(1) surface treatment: taking rare earth salt solution to adjust the pH value to be alkaline, and adding a surface auxiliary agent to obtain rare earth-containing solution for surface treatment;

(2) precipitation reaction: dropwise adding a precipitant into the rare earth-containing solution subjected to surface treatment while stirring, and aging, filtering and washing to obtain a rare earth precipitate;

(3) microwave calcination: and placing the rare earth precipitate into a microwave reactor for microwave heating and calcining to obtain the nano rare earth oxide powder.

2. The microwave preparation method of nano rare earth oxide according to claim 1, characterized in that: the rare earth salt solution is praseodymium salt, neodymium salt or praseodymium-neodymium salt; the concentration of the rare earth salt solution is 0.1-2 mol/L.

3. The microwave preparation method of nano rare earth oxide according to claim 1, characterized in that: the surface auxiliary agent in the step (1) is one of stearic acid, polyacrylamide, citric acid and sodium dodecyl sulfate.

4. The microwave preparation method of nano rare earth oxide according to claim 1, characterized in that: the addition amount of the surface additive is 5-15% of the molar mass of the rare earth salt solution.

5. The microwave preparation method of nano rare earth oxide according to claim 1, characterized in that: the precipitant in step (2) is any one or combination of oxalic acid, carbonic acid, ammonium bicarbonate, oxalate and carbonate, and when the precipitant is a combined precipitant, the ratio of oxalate: carbonate 1:0.2-1.8 or oxalate: carbonate radical: bicarbonate radical 0.8-1.5: 0.5-2: 0.1-0.5.

6. The microwave preparation method of nano rare earth oxide according to claim 1, characterized in that: the addition amount of the precipitant is as follows according to mol ratio: rare earth is added in a ratio of 1-3: 1.

7. The microwave preparation method of nano rare earth oxide according to claim 1, characterized in that: the precipitant is added at a rate of 0.5-3L/min.

8. The microwave preparation method of nano rare earth oxide according to claim 1, characterized in that: the frequency of microwave heating calcination in the step (3) is 915 +/-50 MHz or 2450 +/-50 MHz, and the power is 1-10 kw.

9. The microwave preparation method of nano rare earth oxide according to claim 1, characterized in that: the microwave heating calcination temperature is 800-1200 ℃, and the calcination time is 2-6 h.

10. The microwave preparation method of nano rare earth oxide according to claim 1, characterized in that: the microwave output mode comprises either one or two combination modes of continuous waves and pulse waves.

Technical Field

The invention relates to the field of rare earth, in particular to a microwave preparation method of a nanometer rare earth oxide.

Background

Praseodymium oxide (Pr)₆O₁₁) Is an inorganic compound, having the english name Praseodymium oxide, which can be used for glass, metallurgy, and as a phosphor additive, etc. Praseodymium oxide is one of the important products in light rare earth products. Because of its unique physical and chemical properties, it can be used in the fields of ceramics, glass, rare earth permanent magnet, rare earth cracking catalyst, rare earth polishing powder, grinding material and additive, etc., and is increasingly extensive and good in prospect. Since the 90 s, the praseodymium oxide production technology and equipment in China have been greatly improved and perfected, the product and the yield are increased rapidly, the praseodymium oxide can not only meet the requirements of domestic application amount and market, but also have a considerable amount of export. Therefore, the current production technology, product and yield of praseodymium oxide, the demand for domestic and foreign markets, and the like all belong to the same industry in the world. In the future, the praseodymium oxide industry in China can be expected to be developed more quickly. At present, rare earth resources in China still live at the top of the world, wherein the industrial reserve of praseodymium is about 210 ten thousand tons, which provides a full material basis for the continuous development of praseodymium industry in China in future and is also a unique advantage in China. Praseodymium oxide has a relatively high application prospect in the aspects of rare earth glass, rare earth ceramic, rare earth permanent magnet and the like, and also has a great number of applications in more aspects of corundum grinding wheels, polishing, petroleum catalytic cracking, steelmaking additives and the like.

Neodymium oxide is a rare earth oxide with wide application and is mainly applied to neodymium iron boron (Nd-Fe-B) permanent magnets, television glass shells, glass coloring, fluorescent materials, laser materials and rubber industrial additives, and because the neodymium oxide has elegant color tone and good color change effect, the neodymium oxide is also widely applied to high-tech fields such as ceramics, textile dyeing, superconduction and other functional materials, and the growth momentum is very strong. In recent years, research on the application of neodymium oxide in the field of catalysis is increasingly extensive, such as catalysis of polycarboxylic acid synthesis, fatty alcohol amination, rubber synthesis and the like, and particularly, nanometer neodymium oxide with large specific surface area has better properties and application and higher catalytic activity. The nano neodymium oxide with the concentration of 1.5-2.5% is added into the magnesium alloy or the aluminum alloy, so that the high-temperature performance, the air tightness and the corrosion resistance of the alloy can be improved, and the alloy can be widely used as aerospace materials. In addition, the nanometer yttrium oxide aluminum garnet doped with nanometer neodymium oxide generates short-wave laser beams, and is widely used for welding and cutting thin materials with the thickness of less than 10mm in industry. In medical treatment, the nanometer yttrium oxide aluminum garnet laser doped with nanometer neodymium oxide replaces a scalpel to be used for removing an operation or disinfecting a wound.

Pr-Nd, metal Pr-Nd, is a silver gray metal ingot. The total content of rare earth is more than 99 percent. The neodymium content in the metal is about 75 percent, and the praseodymium content is about 25 percent. The metal praseodymium neodymium is easy to oxidize in the air, belongs to low-toxicity material, and has the toxicity equivalent to that of iron. The rare earth element is hardly absorbed because it is almost completely hydrolyzed in the animal body to form a hydroxide colloid and precipitate. Can be stored in dry environment for a long time. The praseodymium-neodymium alloy is a main raw material for producing high-performance neodymium-iron-boron permanent magnet materials. The percentage of the neodymium iron boron permanent magnet material in the cost of the neodymium iron boron permanent magnet material is about 27%. The praseodymium-neodymium oxide is used for deep processing and for glass, ceramics, magnetic materials and the like. The Dy-Fe alloy is mainly used for making Nd-Fe-B permanent-magnet material, giant magnetostrictive alloy, magneto-optical recording material and nuclear fuel diluent.

At present, a precipitation method, an extraction separation method and an ion exchange method are mostly adopted in the method for preparing the nanometer rare earth oxide (praseodymium oxide or neodymium oxide or praseodymium neodymium oxide), wherein the precipitation method cannot be applied to industrial production due to low rare earth recovery rate, small yield and high cost, and the prepared praseodymium oxide (or neodymium oxide or praseodymium neodymium oxide) has larger granularity and different shapes and is uncontrollable in the heating process due to nonuniform agglomeration caused by internal and external heating of particles during high-temperature reaction of the precipitation method; the extraction separation method has wide application in industrial production, but has the defects of complex process and high consumption cost of an extracting agent; the ion exchange method has the defects of long preparation process, troublesome operation, low rare earth recovery rate, low product purity and yield and the like.

Disclosure of Invention

In order to solve the technical problems, the invention provides a method for preparing a nano rare earth oxide (praseodymium oxide, neodymium oxide or praseodymium neodymium oxide) by adopting a precipitation method and a microwave heating calcination method, and the method ensures that the prepared nano rare earth oxide has uniform granularity and good dispersibility.

The purpose of the invention is realized by the following technical scheme:

a microwave preparation method of nanometer rare earth oxide comprises the following steps,

(1) surface treatment: taking rare earth salt solution to adjust the pH value to be alkaline, and adding a surface auxiliary agent to obtain rare earth-containing solution for surface treatment;

(2) precipitation reaction: dropwise adding a precipitant into the rare earth-containing solution subjected to surface treatment while stirring, and aging, filtering and washing to obtain a rare earth precipitate;

(3) microwave calcination: and placing the rare earth precipitate into a microwave reactor for microwave heating and calcining to obtain the nano rare earth oxide powder.

Preferably, the rare earth salt solution is praseodymium salt, neodymium salt or praseodymium-neodymium salt; the concentration of the rare earth salt solution is 0.1-2 mol/L.

Preferably, in the step (1), the surface auxiliary agent is one of stearic acid, polyacrylamide, citric acid and sodium dodecyl sulfate.

Preferably, the addition amount of the surface auxiliary agent is 5-15% of the molar mass of the rare earth salt solution.

Preferably, the precipitant in step (2) is any one or a combination of oxalic acid, carbonic acid, ammonium bicarbonate, oxalate and carbonate, and when the precipitant is a combined precipitant, the ratio of oxalate: carbonate 1:0.2-1.8 or oxalate: carbonate radical: bicarbonate radical 0.8-1.5: 0.5-2: 0.1-0.5.

Preferably, the addition amount of the precipitant is in a molar ratio of precipitant: rare earth is added in a ratio of 1-3: 1.

Preferably, the precipitant is added at a rate of 0.5-3L/min.

Preferably, the frequency of the microwave heating calcination in the step (3) is 915 +/-50 MHz or 2450 +/-50 MHz, and the power is 1-10 kw.

Preferably, the microwave heating calcination temperature is 800-1200 ℃, and the calcination time is 2-6 h.

Preferably, the microwave output means includes one or a combination of a continuous wave and a pulse wave.

The invention has the following beneficial effects:

1. in the preparation process, the surface auxiliary agent is added, a layer of diaphragm is generated on the surface of the generated crystal grain, the surface energy of the diaphragm is reduced, the crystal grain is prevented from growing in the precipitation process, and the agglomeration of the crystal grain is prevented; the nano powder particles prepared by the aid are finer and more uniform in size.

2. The adding speed of the precipitant is controlled, so that the precipitant is more uniform, the formed precipitant is dispersed in the solution and is covered with the surface auxiliary agent in a complexing manner, meanwhile, the combined precipitant can achieve a better precipitation effect, a coprecipitate is formed, and the dispersibility of the precipitant is better.

3. The invention adopts the microwave heating technology, the surface and the inside of the crystal grains are simultaneously heated in the heating and calcining process, the heating is rapid, the heat conduction is uniform, the resonance is generated in the material to generate heat through the oscillation of the specific microwave frequency, the heating rate and the time are controllable, the decomposed gas is rapidly expanded after the surface auxiliary agent and the oxalic acid/carbonic acid reach the decomposition or combustion temperature, a certain explosion effect is realized, and the prepared product is more delicate, the specific surface area is higher, the granularity is uniform, and the shape of the nano rare earth oxide is consistent.

4. The microwave heating method has the advantages that the heating process is controllable, the heating efficiency is high, the defect of high energy consumption in the traditional preparation method can be effectively reduced, and the microwave heating method has important application prospects.

Detailed Description

In order to make those skilled in the art better understand the technical solutions in the present application, the following will clearly and completely describe the technical solutions in the present application with reference to the embodiments, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and all other embodiments obtained by a person of ordinary skill in the art without making creative efforts based on the embodiments in the present application shall fall within the protection scope of the present application.