In this paper, the preparation process of large particles of rare earth oxides was studied. The rare earth oxides were prepared by coprecipitation method using ammonium bicarbonate and oxalic acid as precipitants, respectively, in cerium and rare earth rare earths. The properties and properties of the prepared large-scale rare earth oxides were characterized by X-ray diffractometer, laser particle size analyzer, specific surface area tester, grinding and polishing machine and scanning electron microscope. The effects of ammonium hydroxide and oxalic acid precipitation methods on the precipitation, the stirring speed, the concentration of the feed solution, the reaction temperature, the dropping speed of the precipitant, the aging time and the burning temperature were studied. The effects of burning temperature on the specific surface area of rare earth oxides were investigated. The effects of the burning temperature on the specific surface area of rare earth oxides were investigated. The effects of ammonium bicarbonate and oxalic acid as precipitants on the flow index of cerium oxide were investigated. The effects of precipitation conditions and burning conditions on the mobility index of large particles cerium oxide were discussed. The thermal decomposition behavior of the precipitates of oxalate precipitates was analyzed by DSC / TG. The kinetic equation of the thermal decomposition reaction was calculated and the reaction mechanism was deduced. X-ray diffraction patterns show that ammonium bicarbonate and oxalic acid precipitation method are prepared by the cerium oxide crystal, belonging to the cubic crystal, fluorite structure. And their grain size and lattice constant were calculated. The amount of the sample obtained by the oxalic acid method is larger than the amount of the sample obtained by the ammonium bicarbonate method by the measurement of the amount of the ejection amount. Scanning electron microscopy (SEM), cerium oxide prepared by ammonium bicarbonate precipitation method is a cauliflower aggregates with good dispersibility. The cerium oxide prepared by oxalic acid precipitation method is hexagonal prism.
Now, rare earth manufacturers of rare earth oxides, the average average particle size of 3 ~ 5μm, loose density of less than 1.2g · cm-3, are primary products, can not meet user requirements. There are many studies on nanosized and ultrafine rare earth compounds, while few studies have been done on large particles of rare earth and high bulk density compounds. The precipitation method is the most widely used method for the chemical synthesis of high purity particles by liquid phase process. The process is simple and easy to operate. Oxalate and ammonium bicarbonate precipitation method is a commonly used method for the preparation of rare earth oxides in the industry. The oxalate precipitation method has the advantages of good crystality of precipitates and easy filtration. The ammonium bicarbonate precipitation method has the advantages of low cost. But they get the rare earth oxide particle size is still less than the requirements of large particles. The aim of this paper is to explore new methods and new processes for preparing large particles and high bulk density rare earth oxides, and to study their fluidity.
Rare earth oxide is an important raw material for the preparation of non-metallic rare earth new materials. The structure and composition of the material must be controlled in order to have the particular properties that the material possessed by the resulting material, which raises the different requirements for the chemical purity and physical properties of the rare earth oxides as raw materials. In order to meet the material users of rare earth oxide physical characteristics of the requirements of China's rare earth production plant on the physical performance of the urgent need for control technology. Rare earth oxide particle performance control is the final step in rare earth smelting processing, but also the beginning of the preparation of rare earth new materials, which is connected to rare earth industry and new materials industry bridge, rare earth industry and new materials industry are of great significance. 1.1.6 1.2.1 rare earth ceramic materials [9,10] rare earth oxides in the fine ceramic materials in the widely used only nearly 20 years. Domestic and foreign ceramic materials, a large number of scientific research personnel to prove that rare earth oxides as a stabilizer, sintering additives added to the different fine ceramic materials, can greatly improve and improve the strength of certain structural ceramic materials, toughness and other technical indicators, Reducing the reaction sintering temperature, thereby reducing the production cost; while rare earth oxides also in the semiconductor gas sensor materials, microwave dielectric materials, piezoelectric ceramic materials and other functional ceramic materials played a very important role. With the development of new fine ceramic materials technology, ceramic materials researchers in the fine ceramic materials through the introduction of a variety of rare earth oxides, greatly improve and improve the performance of ceramic materials, rare earth materials in the field of fine ceramic materials played more and more An important role. All kinds of rare earth materials in the field of fine ceramic continuous research and development