Write an equation for the processing of Neodymium?

Question

Neodymium was discovered by Baron Carl Auer von Welsbach in Vienna in 1885. He separated neodymium, as well as the element praseodymium, from a material known as didymium by means of fractional crystallization of the double ammonium nitrate tetrahydrates from nitric acid, while following the separation by spectroscopic analysis.

Is there an equation for this process to get Neodymium?

Answer 1

Fractional crystallization is a physical process based on the solubility differences between the Pr salt and Nd salt. Regardless of the chemical formula of the salts, the process goes something like this:

Partially (NOT halfway) evaporate the Di salts until crystals form. Filter to separate the crystals. Saving the mother liquor.

We will call the crystals C1 and the mother liquor L1.

C1 is slightly richer in Nd and L1 is slightly richer in Pr.

Dissolve C1 in water, and repeat the partial evaporation.

Call the crystals C2 and the liquor L1A.

Take L1 and evaporate some more to get C1A and L2.

Mix L1A and C1A to get a middle fraction, adding water if necessary to dissolve all of the C1A. Call this M1

C2 is richest in Nd, L2 is richest in Pr, M1 should be similar to your starting mixture.

The enrichment gained on each step is so slight that this procedure was repeated some 10-15 thousand times to separate the two elements. Each time it was repeated, additional fractions were produced. Not an easy process.

Today, ion exchange columns and solvent extractions are used to separate tons of these elements.