Magical Rare Earth Compound: Praseodymium Oxide
Praseodymium oxide, molecular formula Pr6O11, molecular weight 1021.44.
It can be used in glass, metallurgy, and as an additive for fluorescent powder. Praseodymium oxide is one of the important products in light rare earth products.
Due to its unique physical and chemical properties, it has been widely used in fields such as ceramics, glass, rare earth permanent magnets, rare earth cracking catalysts, rare earth polishing powders, grinding materials, and additives, with promising prospects.
Since the 1990s, China’s production technology and equipment for praseodymium oxide have made significant improvements and improvements, with rapid product and output growth. Not only can it meet the domestic application volume and market requirements, but there is also a considerable amount of exports. Therefore, China’s current production technology, products and output of praseodymium oxide, as well as the demand for supply to domestic and foreign markets, are among the top in the same industry in the world.
Properties
Black powder, density 6.88g/cm3, melting point 2042 ℃, boiling point 3760 ℃. Insoluble in water, soluble in acids to form trivalent salts. Good conductivity.
Synthesis
1. Chemical separation method. It includes fractional crystallization method, fractional precipitation method and oxidation method. The former is separated based on the difference in crystal solubility of rare earth nitrates. The separation is based on the different precipitation volume products of rare earth sulfate complex salts. The latter is separated based on the oxidation of trivalent Pr3+to tetravalent Pr4+. These three methods have not been applied in industrial production due to their low rare earth recovery rate, complex processes, difficult operations, low output, and high costs.
2. Separation method. Including complexation extraction separation method and saponification P-507 extraction separation method. The former uses complex extrusion DYPA and N-263 extractants to extract and separate praseodymium from the nitric acid system of praseodymium neodymium enrichment, resulting in a Pr6O11 99% yield of 98%. However, due to the complex process, high consumption of complexing agents, and high product costs, it has not been utilized in industrial production. The latter two have good extraction and separation of praseodymium with P-507, both of which have been applied in industrial production. However, due to the high efficiency of P-507 extraction of praseodymium and the high loss rate of P-204, the P-507 extraction and separation method is currently commonly used in industrial production.
3. The ion exchange method is rarely used in production due to its long process, troublesome operation, and low yield, but the product purity Pr6O11 ≥ 99 5%, yield ≥ 85%, and the output per unit of equipment is relatively low.
1) Production of praseodymium oxide products using ion exchange method: using praseodymium neodymium enriched compounds (Pr, Nd) 2Cl3 as raw materials. It is prepared into a feed solution (Pr, Nd) Cl3 and loaded into an adsorption column to adsorb saturated rare earths. When the concentration of the incoming feed solution is the same as the outflow concentration, the adsorption of rare earths is completed and waiting for the next process to use. After loading the column into cationic resin, CuSO4-H2SO4 solution is used to flow into the column to prepare a Cu H+rare earth separation column for use. After connecting one adsorption column and three separation columns in series, use EDT A (0 015M) Flows in from the inlet of the first adsorption column for elution separation (leaching rate 1 2cm/min）。 When neodymium first flows out at the outlet of the third separation column during leaching separation, it can be collected by a receiver and chemically treated to obtain Nd2O3 byproduct. After the neodymium in the separation column is separated, pure PrCl3 solution is collected at the outlet of the separation column and subjected to chemical treatment to produce Pr6O11 product. The main process is as follows: raw materials → preparation of feed solution → adsorption of rare earth on adsorption column → connection of separation column → leaching separation → collection of pure praseodymium solution → oxalic acid precipitation → detection → packaging.
2) Production of praseodymium oxide products using the P-204 extraction method: using lanthanum cerium praseodymium chloride (La, Ce, Pr) Cl3 as the raw material. Mix the raw materials into a liquid, saponify P-204, and add kerosene to make an extractant solution. Separate the feed liquid from the extracted praseodymium in the mixed clarification extraction tank. Then wash the impurities in the organic phase, and use HCl to extract praseodymium to obtain pure PrCl3 solution. Precipitate with oxalic acid, calcine, and package to obtain praseodymium oxide product. The main process is as follows: raw materials → preparation of feed solution → P-204 extraction of praseodymium → washing → bottom acid stripping of praseodymium → pure PrCl3 solution → oxalic acid precipitation → calcination → testing → packaging (praseodymium oxide products).
3) Production of praseodymium oxide products using P507 extraction method: Using cerium praseodymium chloride (Ce, Pr) Cl3 obtained from southern ionic rare earth concentrate as raw material (REO ≥ 45%, praseodymium oxide ≥ 75%). After extracting praseodymium with the prepared feed solution and P507 extractant in the extraction tank, impurities in the organic phase are washed with HCl. Finally, praseodymium is extracted back with HCl to obtain a pure PrCl3 solution. Precipitation of praseodymium with oxalic acid, calcination, and packaging yield praseodymium oxide products. The main process is as follows: raw materials → preparation of feed solution → extraction of praseodymium with P-507 → impurity washing → reverse extraction of praseodymium → pure PrCl3 solution → oxalic acid precipitation → calcination → detection → packaging (praseodymium oxide products).
4) Production of praseodymium oxide products using P507 extraction method: The lanthanum praseodymium chloride (Cl, Pr) Cl3 obtained from processing Sichuan rare earth concentrate is used as the raw material (REO ≥ 45%, praseodymium oxide 8.05%), and it is prepared into a feed liquid. Praseodymium is then extracted with saponified P507 extraction agent in an extraction tank, and impurities in the organic phase are removed by HCl washing. Then, HCl was used for reverse extraction of praseodymium to obtain pure PrCl3 solution. Praseodymium oxide products are obtained by precipitating praseodymium with oxalic acid, calcining, and packaging. The main process is: raw materials → ingredient solution → P-507 extraction of praseodymium → impurity washing → reverse extraction of praseodymium → pure PrCl3 solution → oxalic acid precipitation → calcination → testing → packaging (praseodymium oxide products).
At present, the main process technology for producing praseodymium oxide products in China is the P507 extraction method using hydrochloric acid system, which has been widely used in the industrial production of various individual rare earth oxides and has become an advanced production process technology in the same industry worldwide, ranking among the top.
Application
1. Application in rare earth glass
After adding rare earth oxides to different components of glass, different colors of rare earth glasses can be made, such as green glass, laser glass, magneto optical, and fiber optic glass, and their applications are expanding day by day. After adding praseodymium oxide to the glass, a green colored glass can be made, which has high-quality artistic value and can also imitate gemstones. This type of glass looks green when exposed to ordinary sunlight, while it is almost colorless under candlelight. Therefore, it can be used to make fake gemstones and precious decorations, with attractive colors and adorable qualities.
2. Application in rare earth ceramics
Rare earth oxides can be used as additives in ceramics to make many rare earth ceramics with better performance. The rare earth fine ceramics among them are representative. It uses highly selected raw materials and adopts easy to control processes and processing techniques, which can accurately control the composition of ceramics. It can be divided into two types: functional ceramics and high-temperature structural ceramics. After adding rare earth oxides, they can improve the sintering, density, microstructure, and phase composition of ceramics to meet the requirements of different applications. The ceramic glaze made of praseodymium oxide as a colorant is not affected by the atmosphere inside the kiln, has stable color appearance, bright glaze surface, can improve physical and chemical properties, improve the thermal stability and quality of ceramics, increase variety of colors, and reduce costs. After adding praseodymium oxide to ceramic pigments and glazes, rare earth praseodymium yellow, praseodymium green, underglaze red pigments and white ghost glaze, ivory yellow glaze, apple green porcelain, etc. can be produced. This type of artistic porcelain has higher efficiency and is well exported, which is popular abroad. According to relevant statistics, the global application of praseodymium neodymium in ceramics is over a thousand tons, and it is also a major user of praseodymium oxide. It is expected that there will be greater development in the future.
3. Application in rare earth permanent magnets
The maximum magnetic energy product (BH) of (Pr, Sm) Co5 permanent magnet m=27MG θ e (216K J/m3)。 And the (BH) m of PrFeB is 40MG θ E (320K J/m3). Therefore, the use of Pr produced permanent magnets still has potential applications in both industrial and civil industries.
4. Application in other fields to manufacture corundum grinding wheels.
On the basis of white corundum, adding about 0.25% praseodymium neodymium oxide can make rare earth corundum grinding wheels, greatly improving their grinding performance. Increase the grinding rate by 30% to 100%, and double the service life. Praseodymium oxide has good polishing properties for certain materials, so it can be used as a polishing material for polishing operations. It contains about 7.5% praseodymium oxide in cerium based polishing powder and is mainly used for polishing optical glasses, metal products, flat glass, and television tubes. The polishing effect is good and the application volume is large, which has become the main polishing powder in China at present. In addition, the application of petroleum cracking catalysts can improve catalytic activity, and can be used as additives for steelmaking, purifying molten steel, etc. In short, the application of praseodymium oxide is constantly expanding, with more being used in a mixed state besides a single form of praseodymium oxide. It is estimated that this trend will continue in the future.