First, the principle of the process

Compared with TBP, P 350 has a higher extraction capacity for rare earths at lower acidity. However, the extraction ability of heavy rare earth elements is less than the light rare earth elements, and therefore extraction system 350 -HNO 3 P applied only mixed rare earth extracted from less pure lanthanum, cerium, praseodymium, neodymium separate praseodymium from Concentrate, and extracting high purity neodymium oxide é’ª and other aspects.

When the P 350 -HNO 3 system extracts and separates rare earth elements, it is widely used as a main process for extracting high-purity lanthanum because it has the smallest distribution ratio of ruthenium and is easily separated from other rare earth elements.

When the P 350 -HNO 3 system is used to extract and separate cerium, the rare earth concentration of the liquid is increased, and the separation effect of cerium and other rare earths is improved by the self-salting effect. In practice, it has been found that a high purity product of La 2 O 3 >99.9% to 99.99% can be obtained by increasing the washing order and the washing amount under the condition that the aqueous phase contains a high rare earth concentration.

Second, P 350 -HNO 3 system extraction process for the production of pure cerium oxide

The light rare earth extracted from the crucible is used as a raw material, and its composition is: La 2 O 3 50%, P r6 O 11 8% to 10%, Nd 2 O 3 32% to 33%, and a small amount of CeO 2 , using P 350 - The HNO 3 system extraction process produces pure cerium oxide, and the process flow is shown below.

Figure P 350 -HNO 3 system extraction process for the production of pure cerium oxide

The extraction process conditions of the process flow shown in the figure are as follows.

(1) The number of stages: extraction of 38 grades; washing of 22 grades; counter-extraction of rich scales of 10 grades;

(2) Flow ratio: fractional extraction V S : V F : V W = 7: 1:1;

Reverse extraction flow ratio V S :V inverse = 4:1

Acid saturation flow ratio V S :V acid = 4:1

(C) the organic phase concentration: 70% P 350 - coal oil.

(4) Liquid concentration: RE x O y 2.1 to 2.3 mol/L; HNO 3 0.5 mol/L.

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