Method for preparing large granular praseodymium neodymium oxide by precipitating ammonium hydrogen carbonate at normal temperature

Abstract

The invention relates to a method for preparing large granular praseodymium neodymium oxide by precipitating ammonium hydrogen carbonate at normal temperature. The method is characterized by comprising the following steps: adding a praseodymium neodymium chloride solution with a concentration of 0.2-0.8 mol / L into a reactor, and directly adding an ammonium hydrogen carbonate solution with a concentration of 1-3 mol / L into the praseodymium neodymium chloride solution at normal temperature, wherein the molar ratio of praseodymium neodymium chloride to ammonium hydrogen carbonate is 1: (3.2-4); adding the ammonium hydrogen carbonate solution in two steps, firstly adding a part of ammonium hydrogen carbonate solution in the first step, stewing and aging for 10-15 hours, adding the rest ammonium hydrogen carbonate solution until complete precipitation, wherein the pH is 6.2-6.5; aging for 10-15 hours at normal temperature, filtering, washing with hot water, and naturally drying to obtain praseodymium neodymium carbonate precipitate with 8 crystal water, roasting the praseodymium neodymium carbonate precipitate to obtain a large granular praseodymium neodymium oxide product with a median particle diameter of 30-40 microns. The method has the advantages that the stepped aging manner is adopted to increase the median particle diameter of the praseodymium neodymium oxide from 1-2 microns to 30-40 microns, so as to greatly improve the granularity of the praseodymium neodymium oxide, and meanwhile, no heating treatment is needed in the precipitating process, so that the production cost is reduced.

Description

technical field [0001] The invention relates to a method for preparing large particles of praseodymium and neodymium oxide by ammonium bicarbonate precipitation at normal temperature, and belongs to the field of material preparation. Background technique [0002] As an important raw material of NdFeB permanent magnet materials - NdPr metal, its production process mainly adopts the method of fluoride system oxide electrolysis, and its raw material is NdPrO (a mixture of NdPrO and NdO), and NdPrO The preparation process mainly includes oxalic acid precipitation and ammonium bicarbonate precipitation followed by burning. However, the production cost of praseodymium and neodymium oxide prepared by oxalic acid precipitation method is relatively high, and the process of preparing praseodymium and neodymium oxide by ammonium bicarbonate precipitation method has become the current development trend. At present, there are many manufacturers providing raw materials for rare earth met...

AI Technical Summary

Problems solved by technology

After years of electrolytic production, it was found that the praseodymium / neodymium oxide raw material prepared by the medium temperature carbon precipitation method has a small particle size, poor fluidity, is easy to fly, pollutes the environment, causes an increase in the total material ratio, and increases the production cost.

Therefore, in order to prepare large particles of NdPrO suitable for electrolysis, CN102531024A provides a method for preparing large particles and spherical NdPrO. The precipitation temperature is controlled at 85-95°C. The method obtains a central particle size of 25-30 μm and uniform distribution. , good fluidity, spherical shape of praseodymium neodymium oxide products, but large energy consumption, high production cost; CN102502760A provides a method for preparing large particles, flaky praseodymium neodymium oxide, the precipitation temperature is controlled at 60 ° C, the method obtains Praseodymium and neodymium oxide products with a central particle size of 28-30 μm and a flaky shape, but it also consumes energy and has high production costs

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