Method for extracting and separating zirconium and hafnium in nitric acid medium

a zirconium and hafnium technology, applied in the field of purification, can solve the problems of not being desired for industrial application, difficult to separate zirconium and hafnium from each other, and the mibk method has the following defects, and achieves the effects of less mass transfer, large extraction capacity, and convenient operation

Inactive Publication Date: 2020-01-23
SOUTH CENTRAL UNIVERSITY FOR NATIONALITIES
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0008]A purpose of the present disclosure is to provide a method for extracting and separating zirconium and hafnium in nitric acid medium. There is no need of using toxic substances during separation process in this method and thus enables clean the separation process of zirconium and hafnium.
[0017]The embodiments of the present disclosure provide the following beneficial effects. A synergistic extraction system consisting of DIBK and a phosphonic acids extraction agent (containing C—P bond) has less mass transfer and large extraction capacity as its properties of preferential extraction of hafnium present at a relatively lower content in mixed solution of zirconium and hafnium. The process flow is simple and easy to operate. The extraction is efficient. Further, there is no need of use of highly toxic substances, e.g. thiocyanic acid or salts thereof in the separation. Therefore, the entire separation process is clean.

Problems solved by technology

Due to “lanthanide contraction”, zirconium and hafnium have substantially identical atomic radius and ionic radius, and very similar physical and chemical properties, so it is very hard to separate them from each other.
This is not desired for industrial application.
However, MIBK method has following defects.
(1) MIBK has a solubility up to 1.7 wt % in water (one of the extraction agents with highest solubility in water), which means a high solvent loss.
(3) MIBK has some smell which degrades the environment in the workshop.
(4) MIBK has a low flash point and thus is likely to start a fire.
The drawbacks of MIBK necessitate improvement or replacement.
For their high toxicity, thiocyanic acid or salts thereof are not environmentally friendly during separation process.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0051]A method for separating zirconium and hafnium, comprising the following steps:

[0052](1) Preparing acidic raw liquid: the aqueous phase contains zirconium and hafnium ions at an initial total concentration of 1.5 mol / L; the hafnium ions are present at a concentration of 0.018 mol / L; the aqueous phase has an acidity of 2.87 mol / L; (NH4)2SO4 is present at a concentration of 0.8 mol / L.

[0053](2) The mixed organic phase consisting of 90% (v / v) of DIBK and 10% (v / v) of Cyanex923 is used as the extraction agent. First, pre-extraction is performed to the extraction agent and 5.5 mol / L nitric acid with equal volume. Then the extraction agent after pre-extraction is used as the organic phase, and the acidic raw liquid is used as the aqueous phase. The phase ratio (organic phase / aqueous phase) is kept at 2:1. Single-stage extraction is performed to the raw liquid at room temperature, with mixing time of the two phases being 10 min. Zirconium is left in the aqueous phase, and zirconium sol...

example 2

[0068]The organic phase consisted of 90% (v / v) of DIBK, 2% (v / v) of Cyanex921 and 8% (v / v) of isooctane (as diluent) and is subjected to pre-extraction in the presence of 6.0 mol / L nitric acid at a volume equal to the organic phase in advance for one time. The aqueous phase contained zirconium and hafnium ions at an initial total concentration of 1.5 mol / L. The concentration of hafnium ions was 0.018 mol / L. The acidity of the aqueous phase was 3.0 mol / L. (NH4)2SO4 was added in an amount of 1.0 mol / L. The phase ratio was kept at 2:1. Single-stage extraction was done at room temperature, with mixing time of the two phases being 5 min. Raffinate and hafnium-containing loaded organic phase were obtained after phase separation. Ammonia liquor was added to the raffinate for precipitation to give zirconium hydroxide precipitate. The loaded organic phase was stripped with 1.0 mol / L potassium carbonate, wherein the phase ratios for both washing and stripping were 1:2 and the mixing time of t...

example 3

[0070]The organic phase consisted of 90% (v / v) of DIBK, 8% (v / v) of Cyanex923 and 2% (v / v) of sulfonated kerosene (as diluent) and is subjected to pre-extraction in the presence of 6.0 mol / L nitric acid at a volume equal to the organic phase in advance for one time. The aqueous phase contained zirconium and hafnium ions at an initial total concentration of 1.5 mol / L. The concentration of hafnium ions was 0.018 mol / L. The acidity of the aqueous phase was 3.0 mol / L. (NH4)2SO4 was added in an amount of 0.8 mol / L. The phase ratio was kept at 2:1. Single-stage extraction was done at room temperature, with mixing time of the two phases being 5 min. Raffinate and hafnium-containing loaded organic phase were obtained after phase separation. Ammonia liquor was added to the raffinate for precipitation to give zirconium hydroxide precipitate containing little hafnium. The loaded organic phase was stripped with 1.0 mol / L sodium carbonate, wherein the phase ratios for both washing and stripping ...

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Abstract

A method for extracting and separating zirconium and hafnium in nitric acid medium mainly includes extraction of acidic raw liquid containing zirconium compounds with a synergistic extraction system consisting of DIBK and a phosphonic acids extraction agent, so that the zirconium goes to the aqueous phase and the hafnium goes to the organic phase, thus achieving separation. There is no need of use of toxic substance throughout the process.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]The present application is a continuation-in-part application based on international patent application No. PCT / CN2018 / 072340, filed on Jan. 12, 2018 and entitled “Method for Extracting and Separating Zirconium and Hafnium in Nitric Acid Medium” and the international patent application claims the priority of the Chinese patent application No. 2018100052447, filed with the Chinese Patent Office on Jan. 3, 2018, and entitled “Method for Extracting and Separating Zirconium and Hafnium in Nitric Acid Medium”, which are incorporated herein by reference in their entirety.TECHNICAL FIELD[0002]The present disclosure relates to the technical field of purification, and specifically to a method for extracting and separating zirconium and hafnium in nitric acid medium.BACKGROUND ART[0003]Zirconium and hafnium are symbiotic in the nature. As commercially available zirconium-containing chemicals normally contain a relatively low hafnium content (mHf / m(...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C22B34/14C22B7/00
CPCC22B7/001C22B7/007C22B34/14C22B3/10C22B3/409Y02P10/20C22B3/3844
Inventor XU, ZHIGAOXU, FEIHE, HONGYANGWU, MINGZHANG, WENJIEHE, ZHENGYANZHANG, RONG
Owner SOUTH CENTRAL UNIVERSITY FOR NATIONALITIES
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