In recent years, the application of lanthanide reagents in organic synthesis has been developed by leaps and bounds. Among them, many lanthanide reagents were found to have obvious selective catalysis in the reaction of carbon-carbon bond formation; at the same time, many lanthanide reagents were found to have excellent characteristics in organic oxidation reactions and organic reduction reactions to convert functional groups. Rare earth agricultural use is a scientific research achievement with Chinese characteristics obtained by Chinese scientific and technological workers after years of hard work, and has been vigorously promoted as an important measure to increase agricultural production in China. Rare earth carbonate is easily soluble in acid to form corresponding salts and carbon dioxide, which can be conveniently used in the synthesis of various rare earth salts and complexes without introducing anionic impurities. For example, it can react with strong acids such as nitric acid, hydrochloric acid, nitric acid, perchloric acid, and sulfuric acid to form water-soluble salts. React with phosphoric acid and hydrofluoric acid to convert into insoluble rare earth phosphates and fluorides. React with many organic acids to form corresponding rare earth organic compounds. They can be soluble complex cations or complex anions, or less soluble neutral compounds are precipitated depending on the solution value. On the other hand, rare earth carbonate can be decomposed into corresponding oxides by calcination, which can be directly used in the preparation of many new rare earth materials. At present, the annual output of rare earth carbonate in China is more than 10,000 tons, accounting for more than a quarter of all rare earth commodities, indicating that the industrial production and application of rare earth carbonate plays a very important role in the development of the rare earth industry.
Cerium carbonate is an inorganic compound with a chemical formula of C3Ce2O9, a molecular weight of 460, a logP of -7.40530, a PSA of 198.80000, a boiling point of 333.6ºC at 760 mmHg, and a flash point of 169.8ºC. In the industrial production of rare earths, cerium carbonate is an intermediate raw material for the preparation of various cerium products such as various cerium salts and cerium oxide. It has a wide range of uses and is an important light rare earth product. The hydrated cerium carbonate crystal has a lanthanite-type structure, and its SEM photo shows that the basic shape of the hydrated cerium carbonate crystal is flake-like, and the flakes are bound together by weak interactions to form a petal-like structure, and the structure is loose, so under the action of mechanical force It is easy to be cleaved into small fragments. The cerium carbonate conventionally produced in the industry currently has only 42-46% of the total rare earth after drying, which limits the production efficiency of cerium carbonate.
A kind of low water consumption, stable quality, the produced cerium carbonate does not need to be dried or dried after centrifugal drying, and the total amount of rare earths can reach 72% to 74%, and the process is simple and a single-step process for preparing cerium carbonate with high total amount of rare earths. The following technical scheme is adopted: a one-step method is used to prepare cerium carbonate with a high total amount of rare earth, that is, the cerium feed solution with a mass concentration of CeO240-90g/L is heated at 95°C to 105°C, and ammonium bicarbonate is added under constant stirring to precipitate cerium carbonate. The amount of ammonium bicarbonate is adjusted so that the pH value of the feed liquid is finally adjusted to 6.3 to 6.5, and the addition rate is suitable so that the feed liquid does not run out of the trough. The cerium feed solution is at least one of cerium chloride aqueous solution, cerium sulfate aqueous solution or cerium nitrate aqueous solution. The R&D team of UrbanMines Tech. Co., Ltd. adopts a new synthesis method by adding solid ammonium bicarbonate or aqueous ammonium bicarbonate solution.
Cerium carbonate can be used to prepare cerium oxide, cerium dioxide and other nanomaterials. The applications and examples are as follows:
1. An anti-glare violet glass that strongly absorbs ultraviolet rays and the yellow part of visible light. Based on the composition of ordinary soda-lime-silica float glass, it includes the following raw materials in weight percentages: silica 72~82%, sodium oxide 6~15%, calcium oxide 4~13%, magnesium oxide 2~8%, Alumina 0~3%, iron oxide 0.05~0.3%, cerium carbonate 0.1~3%, neodymium carbonate 0.4~1.2%, manganese dioxide 0.5~3%. The 4mm thick glass has visible light transmittance greater than 80%, ultraviolet transmittance less than 15%, and transmittance at wavelengths of 568-590 nm less than 15%.
2. An endothermic energy-saving paint, characterized in that it is formed by mixing a filler and a film-forming material, and the filler is formed by mixing the following raw materials in parts by weight: 20 to 35 parts of silicon dioxide, and 8 to 20 parts of aluminum oxide. , 4 to 10 parts of titanium oxide, 4 to 10 parts of zirconia, 1 to 5 parts of zinc oxide, 1 to 5 parts of magnesium oxide, 0.8 to 5 parts of silicon carbide, 0.02 to 0.5 parts of yttrium oxide, and 0.01 to 1.5 parts of chromium oxide. parts, 0.01-1.5 parts of kaolin, 0.01-1.5 parts of rare earth materials, 0.8-5 parts of carbon black, the particle size of each raw material is 1-5 μm; wherein, the rare earth materials include 0.01-1.5 parts of lanthanum carbonate, 0.01-1.5 parts of cerium carbonate 1.5 parts of praseodymium carbonate, 0.01 to 1.5 parts of praseodymium carbonate, 0.01 to 1.5 parts of neodymium carbonate and 0.01 to 1.5 parts of promethium nitrate; the film forming material is potassium sodium carbonate; the potassium sodium carbonate is mixed with the same weight of potassium carbonate and sodium carbonate. The weight mixing ratio of the filler and the film-forming material is 2.5:7.5, 3.8:6.2 or 4.8:5.2. Further, a kind of preparation method of endothermic energy-saving paint is characterized in that comprising the following steps:
Step 1, the preparation of the filler, firstly weigh 20-35 parts of silica, 8-20 parts of alumina, 4-10 parts of titanium oxide, 4-10 parts of zirconia, and 1-5 parts of zinc oxide by weight. , 1 to 5 parts of magnesium oxide, 0.8 to 5 parts of silicon carbide, 0.02 to 0.5 parts of yttrium oxide, 0.01 to 1.5 parts of chromium trioxide, 0.01 to 1.5 parts of kaolin, 0.01 to 1.5 parts of rare earth materials, and 0.8 to 5 parts of carbon black , and then uniformly mixed in a mixer to obtain a filler; wherein, the rare earth material includes 0.01-1.5 parts of lanthanum carbonate, 0.01-1.5 parts of cerium carbonate, 0.01-1.5 parts of praseodymium carbonate, 0.01-1.5 parts of neodymium carbonate and 0.01～1.5 parts of promethium nitrate;
Step 2, the preparation of the film-forming material, the film-forming material is sodium potassium carbonate; first weigh potassium carbonate and sodium carbonate respectively by weight, and then mix them evenly to obtain the film-forming material; the sodium potassium carbonate is The same weight of potassium carbonate and sodium carbonate are mixed;
Step 3, the mixing ratio of filler and film material by weight is 2.5: 7.5, 3.8: 6.2 or 4.8: 5.2, and the mixture is uniformly mixed and dispersed to obtain a mixture;
In step 4, the mixture is ball-milled for 6-8 hours, and then the finished product is obtained by passing through a screen, and the mesh of the screen is 1-5 μm.
3. Preparation of ultrafine cerium oxide: Using hydrated cerium carbonate as the precursor, ultrafine cerium oxide with a median particle size of less than 3 μm was prepared by direct ball milling and calcination. The obtained products all have a cubic fluorite structure. As the calcination temperature increases, the particle size of the products decreases, the particle size distribution becomes narrower and the crystallinity increases. However, the polishing ability of three different glasses showed a maximum value between 900℃ and 1000℃. Therefore, it is believed that the removal rate of glass surface substances during the polishing process is greatly affected by the particle size, crystallinity and surface activity of the polishing powder.