CN1154416A - Extraction of rare earth elements - Google Patents

Abstract

A method whereby rare earth elements are extracted from acidic solutions thereof using, as an extractant, a mixture of phisphinic acid or its salts and other phosphorus compound.

Description

The extraction of rare earth element

In recent years, rare earth element is separated (integrally or respectively reclaiming rare earth element) and seem more and more important from its solution.This method of obtaining has become the theme of many patents (as United States Patent (USP) 4,647,438 and 5,015,447), and these patents are listed in this and drawn and be reference of the present invention.

In the method for these patents, disclosed and used the extraction agent that contains phosphine, as phosphoric acid, phosphonic acids, phospho acid, thiophosphinic acid and ester thereof.In addition, use phosphoric acid ester (as tributyl phosphate) and oxide compound (as trioctyl phosphine oxide) have also been disclosed.Use often these extraction agents to be dissolved in the suitable organic thinner, and from acidic solution during the extracting rare-earth element, this extraction agent is effective especially.Rare earth element is considered to the lanthanon that all ordination number are 57-71, and ordination number is 39 yttrium.But element 61 (promethium) is less interested usually because radioactivity is arranged.

The common method of separation of rare earth elements is as follows from the solution (particularly acidic solution) of rare earth element, and described feed liquid is to obtain by the ore (as monazite, bastnasite stone, xenotime stone, bauxitic ore and other natural crystal) that processing contains rare earth element.

In extraction section the feed liquid of rare earth element solution is handled, this feedstream is contacted upstream or altogether with the dilute solution of extraction agent stream, form raffinate and extraction liquid.Usually in feedstream, also add neutralizing agent (as ammonia) with control pH value.Remove raffinate, and the extraction liquid that will contain the rare earth element of extraction usually is sent in the washer, in this washer, this extraction liquid washed, then it is sent in the back wash extractor, it is carried out back extraction with separation of rare earth elements with denseer acid with diluted acid.In the prior art, hydrochloric acid is preferably to be used to wash and the acid of back extraction from the extraction section extraction liquid, and single (2-ethylhexyl) phosphonic acids one (the 2-ethyl is own) ester is the most frequently used acidic extractant.Also can use two (2,4,4 ,-tri-methyl-amyl) phospho acid.

Although aforesaid method is widely used in obtaining rare earth element, this method has many defectives, if can overcome these defectives, will make this method have bigger commercial appeal.

A defective of aforesaid method is: since employed selection of Extractant do not resemble people needed height, so need multistage mixing-settler to meet the requirements of separation requirement.For example, need 300 grades of mixing-settlers in some Rare Earth Production factory.This extracts with the copper that needs 8-10 level mixing-settler or needs the cobalt/nickel of 10-20 level mixing-settler to separate and makes a sharp contrast.In addition, the phosphonic acids extraction agent in the aforesaid method need use concentrated acid (as 6N hydrochloric acid) to carry out back extraction, thereby needs very high cost with the excessive acid that neutralizes, and causes the chloride ion contamination of the finished product.Use some prior art can solve the chloride ion contamination problem, but because the character of nitric acid make use nitric acid obtain final rare earth element has lower productive rate and do not wish to use it.

Therefore, a kind of method that can solve or roughly slow down the problems referred to above and defective can solve puzzlement for a long time.

The inventor has found a kind of method that can improve the problems referred to above.This method can be obtained rare earth element from tart solution, and in the difference separation of rare earth elements, quite effective when separating " weight " rare earth element (being that ordination number is the rare earth element of 65-71) and from lutetium (Lu), separate ytterbium (Yb) especially.

Present method can make rare earth element reach better in extraction section and washing section to separate (particularly separating Yb from Lu), and can in the reextraction process, use hydrochloric acid soln back extraction Lu from extraction liquid of low concentration, the result, seldom need hydrochloric acid is neutralized, promptly because the highly selective of extraction agent of the present invention, make it in washer, optionally from Lu, to remove Yb, thereby in back wash extractor, have outstanding sour back extraction behavior.

The present invention relates to a kind of method of from the acidic solution that contains rare earth element, obtaining rare earth element, comprising:

1) extract described solution with extraction agent, this extraction agent comprises the mixture of following compounds:

A) following formula P contained compound:

Wherein, R and R ¹Be respectively that replace or alkyl unsubstituted, straight chain or side chain, that have 4-12 carbon atom, X is hydrogen or salt forming group;

B) tetraalkylammonium salt, alkyl wherein can be identical or different, and the total atom number of four alkyl is 14-56;

2) reclaim the rare earth element that is extracted.

The ratio of P contained compound and tetraalkylammonium salt is respectively 3: 1-20: 1, should be respectively 2: 1-15: and 1, preferably be about 10: 1.

The extraction agent temperature is about 10-50 ℃, should be about 15-40 ℃, is preferably about 20-30 ℃; The pH value of extraction section should be tart, promptly less than about 6.5, and preferably about 2-4.

Extractant mixture can randomly be used in combination with thinner.The example of suitable diluent comprises halogenation or not halogenated fat and/or arene, as hexane, heptane, octane, dodecane, benzene,toluene,xylene, ethylbenzene and petroleum cuts such as kerosene, oil fuel, JP-1 etc.

The concentration of extractant mixture in thinner is about 5-95% (volume), is preferably about 10-70% (volume), is preferably about 15-50% (volume).

Suitable P contained compound with above-mentioned formula I comprises:

The di-n-butyl phospho acid; Diisobutylphosphinicacid acid;

Two n-pentyl phospho acid; The di-n-hexyl phospho acid;

Two n-heptyl phospho acid; Di-n-octyl phosphinic acid;

Two (2-ethylhexyl) phospho acid; Two n-nonyl phospho acid;

Two positive decyl phospho acid; Two dodecyl phospho acid;

Two (2,4,4-three hexyl amyl groups) phospho acid;

(2,4, the 4-tri-methyl-amyl)-cyclohexyl phospho acid;

(2,4, the 4-tri-methyl-amyl)-octyl group phospho acid;

Two cyclopentyl phospho acid; The dicyclohexyl phospho acid;

Two ring octyl group phospho acid; Cyclohexyl normal-butyl phospho acid;

Cyclopentyl dodecyl phospho acid; Ring octyl group ethyl phospho acid;

2,4,6-triisopropyl-1,3,5-dioxy phospha alkane-5-hydroxyl-5-phosphenic acid;

Cyclohexyl-1-hydroxy-cyclohexyl phospho acid; Two (2-methyl isophthalic acid-hydroxyl amyl group) phospho acid;

Cyclopentyl-1-hydroxycyclopent base phospho acid;

1-methyl amyl-1-hydroxyl-1-methyl amyl phospho acid;

(1-hydroxyl 1-methylethyl) sec.-propyl phospho acid etc.

Described alkyl can contain 4-12 carbon atom, but preferably has the alkyl of 6-10 carbon atom.X is hydrogen, basic metal or ammonium ion preferably.United States Patent (USP) 4,348,367,4,353,883 have disclosed this phospho acid and salt thereof, and these patents are listed in this and are drawn and be reference.

Tetraalkylammonium salt in the extractant mixture of using in the methods of the invention is that total carbon content of those four alkyl contains compound greater than 18 carbon atoms as 15-56 and none alkyl.Having an alkyl preferably in the tetraalkylammonium salt at least is methyl, and at least one alkyl is that methyl and remaining each alkyl contain 8-12 carbon atom in the best this ammonium salt.The extractant mixture components b) salt is halogenide preferably, as muriate, fluorochemical, bromide etc.

The example of suitable tetraalkylammonium salt comprises: methyl tricaprylammonium chloride; Methyl chloride three nonyl ammoniums; Methyl chloride dotriacontyl ammonium; Methyl chloride three isodecyl ammoniums; Methyl chloride three iso-octyl ammoniums; Iodate methyl trioctylammonium; Tetrabutylammonium chloride etc.

As mentioned above, present method can be used for separating all rare earth elements from acidic solution, and still, described rare earth element is preferably that ordination number is 39, the rare earth element of 65-71, is preferably ordination number and is 39, the rare earth element of 69-71.

According to scope of the present invention, also finding can be by the 3rd amount of component b) replace up to the above-mentioned extractant mixture component of about 20% (volume) a) and b), amount of component b) have a following general formula:

Wherein, R ²And R ³Can be identical or different C ₆-C ₁₀Aryloxy or C ₄-C ₁₂Alkoxyl group, Z is oxygen or sulphur.

The compound of typical above-mentioned formula II comprises:

Di-(2-ethylhexyl)phosphoric acid; Two (2-ethylhexyl) thiophosphoric acid;

Two (dodecyl) phosphoric acid; Two (dodecyl) thiophosphoric acid;

Two (cyclohexyl) thiophosphoric acid etc.

The following example only is used to illustrate the present invention, and except additional claim, these embodiment can not regard limitation of the invention as.Except as otherwise noted, all parts all are weight parts.

Separating factor

The following shaking test in batches that carries out: use mechnical oscillator, made it to reach balance in 30 minutes at the organic phase and the water (being respectively 15ml or 30ml) of 25 ± 1 ℃ of vibration equal volume.After the phase-splitting, record the rare earth concentration of aqueous phase by the EDTA titration, according to mass balance calculate the equilibrium concentration in the organic phase, and confirm this calculation result by organic compound that back extraction extracted and to the analysis (equally by the EDTA titration) of strip liquor.

The partition ratio (D) of concrete metal is defined as the ratio of this metal in the equilibrium concentration of organic phase and aqueous phase, that is: The extraction constant K _ExBe the function of D, but irrelevant with pH, it can be used to calculate more reliable separating factor: $K_{\mathrm{ex}}=D\×\frac{{\left(H^{+}\right)}^3}{{\[{\left(\mathrm{HL}\right)}_2\]}^3}$ Wherein, H ⁺=in the hydrionic equilibrium concentration of aqueous phase;

The concentration of free extraction agent in the organic phase during HL=balance; The extraction factor-beta is defined as: ${{\mathrm{\β}}_2}^1=\frac{K_{\mathrm{ex}}^1}{K_{\mathrm{ex}}^2}$

Embodiment 1

Use 1M two (2,4, the 4-tri-methyl-amyl) phospho acid (BTPP) and the solution of 0.1M Adogen (MATC) in dodecane, wherein, the alkyl in trialkylamine contains 8-10 carbon atom, and its structure is as follows:

Wherein, R is C ₈-C ₁₀Alkyl.

The aqueous phase solution that is used to test is 0.02M rare earth (Lu ³⁺, Yb ³⁺Or Er ³⁺) chloride soln; By adding sodium-chlor the total ionic strength adjustment buffer degree is adjusted to 1M, obtains following result.The data of table 1 show, use extractant mixture of the present invention can increase separating factor.

Table 1

	Separating factor
				????Lu/Yb	??Yb/Tm	??Tm/Er
	??BTPP	????1.45	??2.06				??3.44
??BTPP+MTAC				????2.14	??2.40	??3.18

Embodiment 2

Shaking test the results are shown in table 2, this presentation of results use the situation of rarer hydrochloric acid back extraction rare earth element from the mixed solution of MTAC and BIPP.

Table 2: use the hydrochloric acid back extraction

Extraction liquid: 1M BTPP extraction agent, (volume ratio is 0.1M MTAC at dodecane and dimethylbenzene

90: 10) mixed solution in solution.This extraction liquid extraction has 0.1MLu, Yb or Er.

Stripping workshop: 0.5-2.0NHcl

And carry out other testing sequence according to embodiment 1 described method.

Back extraction per-cent (%)

Hydrochloric acid (N) Lu Yb Tm Er

0.5???????70????75????95????96

1.0???????87????94????100???100

2.0???????98????99????100???100

Embodiment 3 (comparative example)

Use the single 2-ethyl hexyl phosphonic acids list be used for rare-earth industry now (2-ethyl oneself) ester (MEPA) extraction agent, this reagent can be buied in that China is commercially available, and in the Japan and the U.S. production is arranged also.Under the 3 listed data of tabulating show and use hydrochloric acid back extraction ytterbium difficulty relatively from MEPA.The step described in the foregoing description 2 is used in this experiment.

Table 3: use hydrochloric acid back extraction ytterbium from MEPA

The back extraction per-cent of the equivalent concentration ytterbium of hydrochloric acid

0.5?????????????????????1.77

1.0?????????????????????11.6

2.0?????????????????????35.1

Embodiment 4-7

Use is same as the method among the embodiment 1, but replaces BTPP with the following phosphinic acid derivatives of equivalent.In all cases, when using, obtained roughly the same result with MTAC.

Embodiment 4-di-n-octyl phosphinic acid.

Embodiment 5-dicyclohexyl phospho acid.

Embodiment 6-two (2-ethylhexyl) phospho acid.

Embodiment 7-2,4,4-tri-methyl-amyl cyclohexyl phospho acid.

The result of back extraction identical with shown in the embodiment 2.

Embodiment 8-11

Use is same as the method among the embodiment 1, but replaces MTAC with following trialkyl ammonium methyl derivative, obtains identical result.

Embodiment 8-Diethylaminoethyl (trioctylphosphine) ammonium.

Embodiment 9-methyl chloride three (dodecyl) ammonium.

Embodiment 10-methyl chloride (three decyls) ammonium.

Embodiment 11-iodate methyl (trioctylphosphine) ammonium.

Embodiment 12-chlorination tetra-n-butyl ammonium.

Effect shown in the similar embodiment 2 of the effect of back extraction.

Claims (10)

1. method that reclaims rare earth element from acidic solution comprises:

1) extract described solution with extraction agent, this extraction agent comprises the mixture of following compounds:

A) following formula: compound:

Wherein, R and R ¹Be respectively that replace or alkyl unsubstituted, straight chain or side chain, that have 4-12 carbon atom, X is hydrogen or salt forming group;

B) tetraalkylammonium salt, alkyl wherein can be identical or different, and the total atom number of four alkyl is 14-56;

2) reclaim the rare earth element that is extracted.

2. the method described in claim 1 is characterized in that extraction agent is used in combination with thinner.

3. the method described in claim 1 is characterized in that rare earth element is by obtaining with sour back extraction extraction liquid.

4. the method described in claim 1 is characterized in that R and R ¹Be identical.

5. the method described in claim 4 is characterized in that R and R ¹Be both the 2-ethylhexyl.

6. the method described in claim 4 is characterized in that R and R ¹Be both 2,4, the 4-tri-methyl-amyl.

7. the method described in claim 1 is characterized in that components b) at least a alkyl be methyl.

8. the method described in claim 1 is characterized in that components b) an alkyl be methyl, remaining each alkyl contains 8-12 carbon atom.

9. the method described in claim 6 is characterized in that components b) an alkyl be methyl, remaining each alkyl contains 8-12 carbon atom.

10. the method described in claim 3 is characterized in that using acid elution rare earth element phase before the back extraction.