A kind of preparation method of praseodymium neodymium oxide

Abstract

The invention discloses a method for preparing praseodymium-neodymium oxide. The method comprises the following steps: adding bottom water (salt-free water) to a precipitation reactor; gradually adding a neodymium-praseodymium chloride solution and a sodium carbonate (or sodium bicarbonate) solution to the precipitation reactor according to the stoichiometric ratio; adjusting the flow ratio, and controlling the initial precipitation pH value to gradually ascend to 8-9; gradually reducing the pH to 6.0-6.5 after keeping for 30-40 minutes; after finishing the participation process, ageing for 1-2 hours; washing and burning to obtain praseodymium-neodymium oxide. The cheap precipitant sodium carbonate (or sodium bicarbonate) is adopted as a raw material, and a praseodymium-neodymium oxide product of which NaL<2>O / REO is smaller than 500ppm is participated, so that the Na<2>O content in the praseodymium-neodymium oxide product taking sodium carbonate (or sodium bicarbonate) as the precipitant is reduced, the production cost of the product can be reduced, and harmful acid wastewater generated in precipitation by using oxalic acid or ammonia-nitrogen wastewater generated in precipitation by using ammonium bicarbonate can be avoided.

Description

technical field [0001] The invention relates to a preparation method of praseodymium and neodymium oxide. Background technique [0002] Praseodymium neodymium oxide is an important raw material for the preparation of permanent magnet materials. Most of the early praseodymium neodymium oxide products use ammonium bicarbonate as a precipitant to react with the corresponding rare earth chloride liquid, and then burn them to prepare. However, this process will produce a large amount of ammonia nitrogen wastewater. For wastewater The treatment of rare earth pollutants is a huge problem. With the implementation of the "Rare Earth Industrial Pollutant Discharge Standard" (GB 26451-2011), a large number of enterprises have stopped using ammonium bicarbonate as a precipitant and switched to other precipitants, such as oxalic acid and carbonic acid. sodium or sodium bicarbonate. Among them, oxalic acid is expensive, and the precipitation wastewater produced is acidic wastewater, and ...

AI Technical Summary

Problems solved by technology

But in using sodium carbonate or sodium bicarbonate as precipitant, the composition of precipitant Na + It is easy to form mixed crystals with rare earth precipitation and enter the product

Rare earth carbonates with high sodium content are easily mixed with the crucible main material (SiO 2 ,Al 2 o 3 ) to form a eutectic compound, and then corrode the crucible, causing greater loss of the crucible and increasing production costs

At the same time, in the metal electrolysis process of praseodymium and neodymium oxide products with high sodium content, the long-term accumulation of sodium ions entering the molten salt will lead to a decrease in current efficiency and increase the production cost of customers

[0003] In the prior art, people only pay more attention to impurity ions such as calcium magnesium aluminum, and pay little attention to the content of sodium ions in oxides.