First, strengthen high-temperature concentrated sulfuric acid roasting method Beijing Research Institute of Nonferrous metals from the 1970s began the development of concentrated sulfuric acid roasting smelting Baotou mixed rare earth concentrate, we have developed a first-generation, second generation, third generation of sulfuric acid The method, in which the concentrated sulfuric acid high-temperature intensification roasting method ("three generations" acid method) has been put into use since the 1980s, has been treated as a treatment of Baotou rare earth concentrates by concentrated sulfuric acid high temperature intensification roasting process. First, the concentrate is dried by an external heating rotary kiln; in the rotary kiln, the rare earth concentrate is mixed with concentrated sulfuric acid, and reacted at a certain temperature (500-600 ° C), and the rare earth concentrate is completely decomposed to form a rare earth sulfate; cold water leaching into the solution of rare earth rare earth sulfates; phosphorus acid group removing iron powder, adjusting the pH with magnesium oxide or calcite, give purer rare earth sulfate, or a rare earth transition chloride by extraction, or extraction and separation as required. Thorium generating firing at high temperatures to strengthen the water-insoluble pyrophosphates (or phosphate) remain in the slag flooding. The advantage of the process is that the quality of the concentrate is not high, the process is continuous and easy to control, the reagent consumption is low, the running cost is low, and the mass production is easy. The disadvantage is that strontium phosphate enters the slag in the open form and cannot be recycled, resulting in radioactive pollution and waste of cesium resources; waste gas containing fluorine and sulfur and industrial wastewater polluting the environment. The “three wastes†produced during the production of rare earths have attracted wide attention as early as the 1980s. The waste gas produced by the high-temperature enhanced roasting process of concentrated sulfuric acid is mainly acid mist containing sulfuric acid and hydrofluoric acid and a small amount of fluorosilicic acid roasting tail gas; the waste water is mainly ammonium salt wastewater generated during the process of extracting and sorting rare earth concentrate, and The main components are ammonium sulfate and ammonium chloride; the waste residue mainly contains iron, phosphorus, calcium compounds and antimony, which will cause long-term radioactive contamination. In response to these "three wastes", relevant experts have put forward some suggestions for governance. For example, Wang Junlan of Baotou City and Rare Earth Group Corporation proposed a method for splitting and dividing according to the characteristics of each major pollutant and recycling. \The exhaust gas generated by roasting is treated by three-step method: using cooling and spray absorption method to obtain condensed acid solution and sprayed acid solution. The mixed dilute acid solution is concentrated by heating and separated to obtain concentrated sulfuric acid and fluorine-containing liquid. The liquid is treated by a synthetic method to obtain a fluorine salt, so that the tail gas can be discharged to the standard, and the pollution of the tail gas purification wastewater is also eliminated, and the cryolite required for the production of rare earth sulfuric acid and aluminum smelting industry can be obtained; for the ammonium salt wastewater, It is mainly used to increase the concentration of ammonium sulfate and ammonium chloride wastewater with less impurities caused by acid rare earth smelting by electrodialysis and reverse osmosis to 12% to 14%, and then obtain the conventional three-effect evaporation and cooling crystallization method. Qualified ammonium chloride and ammonium sulfate products, which can not only treat ammonium salt wastewater, but also recover a large amount of ammonium sulfate and ammonium chloride. For the waste containing slag, the low-temperature roasting, separation of the water leaching residue and neutralization slag, and obtaining rich The slag is neutralized and the primary amine is extracted and separated to convert hydrazine into cerium nitrate. Hubei ruiyate Automobile Co.,Ltd , https://www.nbruiyate-automobile.com