US 5,132,016 A · Solvent prestripping in a Zr/Hf separation liquid-liquid extraction (LLX) circuit

Abstract

A process for producing nuclear grade zirconium and a liquid-liquid separation circuit for separating zirconium from hafnium are provided. The process employs an aqueous feed of ZrOCl.sub.2 in the presence of thiocyanate, an organic solvent and acid and a series of high mass transfer efficiency pulse columns in which are conducted the iron extraction, hafnium extraction, zirconium stripping, hafnium scrubbing and zirconium and hafnium thiocyanate recovery processes required to produce substantially hafnium-free nuclear grade zirconium. A feed zone mixer-settler separates thiocyanate and zirconium injection points and permits the prestripping of zirconium prior to the main stripping operation. All of the scrubbed solvent and the thiocyanate are regenerated. Higher concentrations, smaller flows, and compact equipment result in the present process requiring substantially reduced in-process inventories as compared to previously known Zr/Hf separation processes. The Zr/Hf separation process described herein also achieves further processing efficiencies not produced by the prior art.

Claims17

Dependent claims

A process for separating zirconium values from hafnium values to produce nuclear grade zirconium, comprising:

(a) extracting the iron from an aqueous ZrOCl.sub.2 feed with an organic solvent;
(b) directing the iron-free aqueous ZrOCl.sub.2 feed mix to a mixer-settler where said feed is mixed with raffinate from a zirconium stripper;
(c) contacting the iron-free aqueous ZrOCl.sub.2 feed/zirconium stripper raffinate mix with an organic solvent in the mixer settler to prestrip a quantity of zirconium from the zirconium loaded solvent and to produce a mixer-settler raffinate zirconium feed;
(d) adding a thiocyanate-containing aqueous feed to the mixer-settler raffinate zirconium feed and extracting hafnium values from the zirconium-thiocyanate containing feed thus formed in the presence of an organic solvent;
(e) stripping zirconium values from the zirconium-thiocyanate-containing solvent in the presence of a weak concentration of a first acid;
(f) scrubbing the stripped feed in the presence of a second acid to further remove hafnium values from said stripped feed to produce a scrubber raffinate and thiocyanate-containing solvent;
(g) refluxing said scrubber raffinate to step (e) and extracting thiocyanate values from the scrubber raffinate;
(h) recovering thiocyanate from the Hafnium extracted feed in the presence of a solvent and a high concentration of said first acid and
(i) regenerating said solvent.

6 more elements

A liquid-liquid separation circuit for separating the hafnium from the zirconium in an aqueous ZrOCl.sub.2 feed in the presence of thiocyanate, acid and an organic solvent to produce a zirconium raffinate having an acidity of at least 0.8 [H]/Zr, said separation circuit including a plurality of fluidically interconnected column means for separating said hafnium from said zirconium, each said column means including organic solvent feed means for directing organic solvent into one end of said column means and aqueous feed means for directing an aqueous liquid into an opposite end of said column means, said plurality of column means including at least iron extraction column means for removing iron from said ZrOCl.sub.2 feed, hafnium extraction column means for extracting hafnium values from a zirconium-thiocyanate-containing feed;

zirconium stripping column means for stripping zirconium values from zirconium-thiocyanate-containing solvent and producing a stripper raffinate;
hafnium scrubbing column means for further removing hafnium values from feed produced by said zirconium stripping column means;
zirconium-thiocyanate recovery column means fluidically connected directly to said hafnium extraction column means for producing a zirconium raffinate;
and hafnium-thiocyanate recovery column means fluidically connected directly to said hafnium scrubbing column means for producing hafnium raffinate;
said circuit further including zirconium prestripping means fluidically interconnected to said iron extraction column means, said hafnium extraction column means, said zirconium stripping column means and a source of thiocyanate for prestripping a quantity of zirconium from a mixture of iron-free ZrOCl.sub.2 feed and stripper raffinate.

2 more elements

Dependencies are inferred from the claim text.

Solvent prestripping in a Zr/Hf separation liquid-liquid extraction (LLX) circuit

Life of this patent

Solvent prestripping in a Zr/Hf separation liquid-liquid extraction (LLX) circuit

Life of this patent

Abstract

Claims17