Magnesium cerium nitrate separation

Magnesium cerium(III) nitrate, 3Mg(N03)2-2Ce(N03)3-24H20, separation of praseodymium from lanthanum by, 2 57 Magnesium chloride, anhydrous, 1 29 5 154n. 6 9 Magnesium cyclopentadienide, 6 11 Magnesium rare earth nitrates,... 

The monazite sand is heated with sulfuric acid at about 120 to 170°C. An exothermic reaction ensues raising the temperature to above 200°C. Samarium and other rare earths are converted to their water-soluble sulfates. The residue is extracted with water and the solution is treated with sodium pyrophosphate to precipitate thorium. After removing thorium, the solution is treated with sodium sulfate to precipitate rare earths as their double sulfates, that is, rare earth sulfates-sodium sulfate. The double sulfates are heated with sodium hydroxide to convert them into rare earth hydroxides. The hydroxides are treated with hydrochloric or nitric acid to solubihze all rare earths except cerium. The insoluble cerium(IV) hydroxide is filtered. Lanthanum and other rare earths are then separated by fractional crystallization after converting them to double salts with ammonium or magnesium nitrate. The samarium—europium fraction is converted to acetates and reduced with sodium amalgam to low valence states. The reduced metals are extracted with dilute acid. As mentioned above, this fractional crystallization process is very tedious, time-consuming, and currently rare earths are separated by relatively easier methods based on ion exchange and solvent extraction. 

Cement, laboratory, 1 189 Cerite, extraction of, 2 44 Cerium, phosphor containing strontium sulfide and, 3 23 separation of, from rare earth mixtures, 2 43, 47, 48 test for, 2 50 Cerium amalgam, 1 15 Cerium-group earths, separation of, from yttrium earths by doublesulfate method, 2 44, 46 Cerium (III) magnesium nitrate, 2Ce(N03)s-3Mg(N03)2-24H,0, separation of praseodymium from lanthanum by, 2 57 Cerium(III) nitrate, 2 51 Cerium (IV) nitrate, basic, 2 49 Cesium, cesium azide for preparation of, 1 79... 

The principal source of thorium is monazite (p. 425), a phosphate of cerium and lanthanum with up to 15% of thoria. It is dissolved in concentrated sulphuric acid and the thorium phosphate precipitated with magnesium oxide. The washed phosphate heated with sodium carbonate gives crude thoria, ThOg, which is converted to the soluble oxalate and separated from the insoluble oxalates of cerium and lanthanum. After ignition to oxide the nitrate is made, purified by recrystallisation, and again calcined to thoria. 

This method has been considered the best of the classical separation procedures for producing individual elements in high purity. The most suitable compounds are ammonium nitrates (for La, Pr, and Nd) and double magnesium nitrates (for Sm, Eu, Gd). Manganese nitrates have also been used for separation of lanthanides of the cerium group (La-Nd). Bromates and sulphates have been used in the separation of the yttrium group (being the heavy lanthanides or HREE)... 

If the material is to be separated into the cerium and yttrium groups of rare earths by precipitation of the double sulfates of the former, removal of the last trace of cerium is unnecessary since it does not seriously interfere in the fractionation of the cerium group double magnesium nitrates. It is important, however, that there be no ceriuni in a bromate series,... 

Yttrium-group earths, containing samarium, separation from mona-zite by magnesium nitrate, 2 56 separation by fractional crystallization of bromates, 2 56, 62 separation from cerium earths by double-sulfate method, 2 44, 46... 

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