DE2645130A1 - PROCESS FOR THE REMOVAL OF ENRICHED IRON FROM ORGANIC LIQUID-LIQUID EXTRACTS CONTAINING DI (AETHYLHEXYL) PHOSPHORIC ACID - Google Patents

Description

DIPL.-ING. SCHWABE DR. DR. SANDMAIR

PATENTANWÄLTE 8 MÜNCHEN 86, POSTFACH 86 02 45

Lawyer File 27

6. Οκτ.

Eduardo Diaz Nogueira,
Angel Luis Redondo Abad, Jose Manuel Regife Vega Madrid / Spain

Process for removing enriched iron from di- (2-ethylhexyl) phosphoric acid-containing organic

Plüssig-Plüssig extracts

Di- (2-ethylhexyl) phosphoric acid is used in technology as a cation exchanger in the extraction of 6-valent Uranium from sulphate solutions, in the separation of uranium and vanadium, in the separation and purification of the Rare earths, in the separation of cobalt and nickel, in the extraction of beryllium from sulphate solutions, in the separation of zinc, iron, manganese and cobalt, in the extraction of zinc and for numerous used for other purposes.

V / W -

fOSO) w8272 8 Munich 80. MauerkirchcrsiraUe 45 banks: Bayerische Vereinsbank Munich 453100

ITAPiTATENT Munich
JRG d

709815 / 116a

¹ JR 7043 telegrams: BERGSTAPi ⁷ PATENT Munich Hypo-Bank Munich 3890002624

"83310 TELEX: 05 24 560 BERG d Postscheck Munich 653 43 - 808

In all of these processes, the liquids being handled as aqueous feed generally contain different ones Ionic impurities, iron being the most common. The affinity of di- (2-ethylhexyl) phosphoric acid against iron is so strong that the latter falls below even at very low concentrations Formation of a complex is quantitatively extracted, which polymerizes in the organic phase and has a molecular weight in the order of 2000. This phenomenon leads to a significant decrease over time the capacity of the cation exchanger and also to a strong increase in the viscosity of the organic phase, which makes their usability as extractants for many purposes difficult or even prevents.

Two methods are known for separating iron from such organic phases.

The first method is that the organic phase with a strongly alkaline sodium hydroxide or Sodium carbonate solution washes. This treatment leads to a breakdown of the polymers with the formation of iron hydroxide and the sodium salt of di (2-ethylhexyl) phosphoric acid. The presence of a precipitate of iron hydroxide in the aqueous phase and the high dissociation of the sodium salt of the acid have the consequence that di- (2-ethylhexyl) phosphoric acid dragged along and their soluble

speed in the aqueous regeneration phase is so high that this process is uneconomical on an industrial scale will.

In the second method, the organic phase is washed with an aqueous solution of 6 m hydrochloric acid. This treatment also leads to a breakdown of the polymer with the formation of an anionic complex of the iron ion in a chloride-containing medium (Cl ₁ -Pe), which shifts the cation exchange between the iron ions (Pe) of the organic phase and the hydrogen ions (H) of the aqueous phase. This process is economically unattractive because of the high acid consumption.

In this second method, the consumption of hydrochloric acid due to the equilibrium between the two phases during the treatment of the iron ion certainly. As a result, as soon as a certain concentration of iron is reached, the acidic one aqueous solution must be derived, which always has a small proportion of the acid equivalents used leads, with the result that the consumption of acid is normally 10 to 20 times the stoichiometric Amount of iron is.

The object of the present invention is a method for

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Removal of enriched iron from organic phases containing di- (2-ethylhexyl) phosphoric acid, by means of an aqueous acidic solution containing chloride ions and the subsequent treatment of the regeneration liquid, to make them reusable by separating the iron.

The method according to the invention consists of 3 stages.

In the first stage of the process, the di-2- (ethylhexyl) organic phase containing phosphoric acid and "poisoned" by iron brought into contact with an acidic solution, which contains chloride ions in such a concentration that between the aqueous and the organic Phase an exchange of the H ions by Pe ions takes place, which leads to a "Regenerderuig" of the organic Phase leads.

The second stage consists in the extraction of that contained in the regeneration liquid from the previous stage Iron by contacting with an organic solution containing an anion exchanger in the Way that by exchanging an amount of hydrochloric acid stoichiometrically equivalent to the amount of iron precipitated the regeneration liquid can be reused in the first stage.

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The third stage consists in re-extraction of the iron from the organic containing the anion exchanger Phase from the previous stage by contacting with water and with the aim that the iron-free organic Phase can be returned to the second stage for reuse.

Overall, the iron from the organic phase containing the di- (2-ethylhexyl) phosphoric acid is transferred into water by means of two intermediate carriers, ie an acidic chloride solution and an organic solution of an anion exchanger, which according to the process according to the invention is only an amount of hydrochloric acid equivalent to the amount of iron excreted and requires the amount of water necessary to remove the iron ions excreted from the system.

In the first or regeneration stage, the reaction mechanism is a cation exchange that in simplified Shape can be represented by the following equilibrium:

3RH (o) + Cl ₄ PeIaq)

where RH is di- (2-ethylhexyl) phosphoric acid. In principle, the regenerant can be any mixture of an inorganic mineral acid and a soluble one

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Be chlorides, with hydrochloric acid for practical reasons alone or in admixture with sodium or calcium chloride or sulfuric acid in admixture with sodium chloride is preferred.

The optimal concentrations of these reagents in the regeneration liquid are obviously different from that of Concentration of di- (2-ethylhexyl) phosphoric acid in the organic phase and the amount of residual iron that the respective application requires, depending.

For a very common concentration of 10 % by volume in petroleum, the optimal concentration of hydrochloric acid in the regeneration liquid is between 4 and 5 moles.

The regeneration of the di- (2-ethylhexyl) phosphoric acid can in any extraction device with the aid of solvent and preferably carried out in mixer-settling devices, which type of apparatus was constantly used in the present experiments.

The time of stirring or contact required to establish equilibrium depends on the concentrations of the organic and aqueous phases and the strength of the stirring. In any case, lay

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this time below 10 minutes and preferably below 3 minutes.

The separation of the phases does not present any difficulties.

In a single contact between the regenerant in the form of 5 _S 5 m hydrochloric acid and 10
From the organic phase containing di- (2-ethylhexyl) phosphoric acid, the quantitative ratio being selected for practical reasons, is it possible to use more than 90? of iron to remove, taking an organic
Phase _{3 is obtained} which contains iron in amounts of less than 150 mg / l.

The temperature of the process can be between 10 and 50 ° C.

The concentration of di- (2-ethylhexyl) phosphoric acid in the organic phase can be between 1 and 50 vol.
be.

The chloride ion concentrations in the regenerant can vary between 0.1 and 12 moles, with the best results in the range of 4.0-6.0 moles can be obtained.

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Another aim of the method according to the invention is the removal of iron from the aqueous reagent used for the regeneration of di- (2-ethylhexyl) phosphoric acid has been used for the purpose of reusing it.

To extract the iron in this second stage, an organic phase is used, which consists of three components, an extractant, a modifier and a diluent.

The extractant belongs to the group of amines, the primary, secondary, tertiary or quaternary ammonium bases can be, have long-chain alkyl radicals, are sparingly soluble in water and have molecular weights of more than Own 200.

The second component of the organic phase, the modifier, has the task of facilitating the separation of the phases during the extraction. Alcohols with 8 to 1h carbon atoms are expediently used for this purpose.

The third component, i.e. the diluent, serves as a carrier for both reagents and causes the reduction the viscosity of the medium. Coals can be used

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Hydrogen or mixtures thereof, as they are in the fractionated Distillation of the petroleum incurred, can be used.

The binding of iron to the extractant is based on the fact that this element is present in solutions of chloride ions an anionic chloride complex (Cl ^ Pe) according to forms the following equilibrium:

4 Cl "+ .. Pe ³⁺ ^ r ± CI ₁

The iron is extracted via an ionic exchange mechanism between the chloride of the amine compound and the complex iron ion. In the case of the chloride of a secondary amine (R ₂ H ₂ NCl), the equilibrium can be represented by the following equation:

+ Cl

Shifting this reaction to the right (extraction direction) leads to depending on how the process is carried out an increase in the Pe and Cl ion concentration, in particular the latter, which leads to the formation of the anionic Iron complex leads.

The iron can be extracted with the help of any extractor and the help of solvents,

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preferably be carried out in mixer-settling devices, which type of device was used in the experiments at hand was used.

The length of time required for stirring or contact to establish equilibrium depends on the Concentrations of the organic and aqueous phases and the degree of agitation. In any case, that time was less than 10 minutes, preferably 2 to 5 minutes.

The separation of the phases offers when using a Modifiers in the organic phase do not pose any difficulties.

With a single contact between the organic phase containing the amine and the regenerant, the mutual amounts being practical can be chosen, more than 95% iron can be removed from the latter, resulting in an aqueous extract with a concentration of iron results in less than 40 mg / l.

The temperature of the reaction fluctuates between 10 and 50 ⁰ C.

The concentrations of the amine in the organic phase can between 1 and 5055 and fatty alcohol between 0 and 25? vary depending on the concentration of iron and chlorides in the regenerant.

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The re-extraction of the iron from the organic phase, the contains the amine, is carried out with water and is based on the dissociation of the anionic iron complex (Cl ^ Fe) in the absence of chloride ions. Depending on the mutual Quantities of the organic and aqueous phase can be more or less concentrated solutions of Iron chloride can be obtained, as well as a more or less strong emptying of the organic phase.

After re-extraction, the organic phase is practically completely freed from iron and can be used for the process find use again.

The losses of the regenerant (hydrogen chloride acid) that occur in the process according to the invention, remain limited to the stoichiometric consumption, which corresponds to the iron, plus one small amount required to maintain the water balance in the system.

This method can also be used to make di- (2-ethylhexyl) phosphoric acid to regenerate from other ions that form anionic complexes in a chlorine-containing medium, such as for Example chrome, aluminum, etc.

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example

This example shows the regeneration of di- (2-ethylhexyl) phosphoric acid, assuming an organic phase of the following composition:

Di- (2-ethylhexyl) phosphoric acid: 10 vol.? Petroleum (Campsa): 90 vol. %

This organic phase has an iron concentration of 0.338 g / l. The organic phase is then in one stage with a solution of 5.9 M hydrochloric acid brought in contact. The quantitative ratio of the organic to the aqueous phase was 10. The following results were obtained obtain:

Iron in organic phase: 0.110 g / l. Iron in aqueous phase: 2.19 g / l

Example 2

This example is intended to show that all indicated concentrations of the regenerant for the regeneration of the Di- (2-ethylhexyl) phosphoric acid can be used:

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The organic phase has a composition as in Example 1 on.

The concentrations of iron in the organic phase, the concentrations of the regenerant and the The proportions of the organic to the aqueous phase were as follows:

attempt
1 Organic
Phase | gPe / l]
0.240 Regenerants
JHCl] | M / l]
5.0 Quantity ratio
the organic to
aqueous phase
30th 2 0.240 20th 3 0.338 10 4th 0.338 5 VJI 0.240 5 6th 0.338 5 7th 0.338 10 5.0 5.0 5.0 4.0 3.9 3.0

Both phases are contacted in one step, with the following results being obtained:

Obtained aqueous phase [gFe / l]

3.57 2.60 2.45 1.37

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attempt
1 Obtained organic
Phase | _gFe / lJ
0.110 2 0.090 3 0.095 4th 0.068

264513Q

attempt Obtained organic
Phase JgFe / l] 5 0.120 6th 0.063 7th 0.190

Aqueous phase obtained [gPe / lj

2.23
1.34
1.48

example

This example is intended to show that all of the specified compositions of the regenerant can be used to regenerate the di- (2-ethylhexyl) phosphoric acid.

The organic phase has a composition as in the previous examples.

The concentration of iron in the organic phase, the composition of the regenerating solution and the weight ratio of the organic and aqueous phases are the same following:

Experiment organic regeneration phase [gFe / i] solution [M / 1]

HCl NaCl HoJ

0.338

0.338 0.240 0.338 0.338 0.338

5.0 1.0 4.0 1.1 4.0 1.1 2.9 2.2 2.0 3.3 2.0 2.0

2.0

Quantities of the organic: aqueous phase

10

15 20 10 10 10

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Both phases are contacted in one step, with the following results being obtained:

Try Obtained Organic Obtained Aqueous

Phase JgFe / l] phase [gPe / l]

1 0.098 2.3 ² I.

2 0.115 3, ^ 0

3 0.095 2.70

4 0.115 2.24

5 0.165 1.69

6 0.123 2.13

EXAMPLE 4

This example shows the separation of iron from the regeneration liquid of di- (2-ethylhexyl) phosphoric acid. The composition of the organic phase was as follows:

Amberlite - LA-2- (commercial secondary amine) isodecanol 6%

Petroleum (campsa)

The organic phase is in one stage with the regenerant the di- (2-ethylhexyl) phosphoric acid in contact brought. The organic phase loaded with iron is with

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Water re-extracted in one step.

The concentrations of iron in the regenerant and the weight ratio of organic to aqueous The phases of extraction and re-extraction were as follows:

Attempt regeneration- quantity ratio- quantity ratio-

solution jgFe / lJ nisse of the organs of organic:

niches: aqueous aqueous re-extracts extracts

1.80 7.20

0.67 3.23

1.25 5.59

2.54 10.06

1.98 10.23

2.50 17.12

The results were as follows:

1 3.24 2 3.04 3 3.20 4th 3.48 5 2.69 6th 2.97

attempt
1 Aqueous extracts
solution
IgFe / 1]
0.20 Organic
Extraction
solution
[gPe / 1]
1.81 Watery
Re-extract.
JgFe / 1]
12.20 Organic
Re-extract.
JgFe / l]
0.12 CVl 0.63 3.77 11.60 0.18 3 0.43 2.79 12.40 0.58 4 - 0.20 1.47 13.00 0.18 5 0.08 2.54 13.50 1.22 6th 0.27 2.53 18.50 1.45

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Example 5

This example shows the results of the regeneration of the di- (2-ethylhexyl) phosphoric acid and the removal of the iron compiled from the overflow of the regeneration, the experiments being continuous and were carried out on a pilot scale. The procedural stages are in the figure with Roman numerals and the main streams denoted with Arabic numerals.

In these experiments, the procedure consists of the following stages:

Regeneration of di- (2-ethylhexyl) phosphoric acid I Extraction with LA-2 II

Re-extraction with water III

The organic extract comes from the one preceding the extraction Level and has the following composition:

Iron 0.29 g / l

Zinc 0.26 g / l

Acidity [Hei] <.0.5 g / l

The reagent used for regeneration was a chlorine

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Hydrogen acid solution with a concentration of 4.9 Minor.

The following are the amounts and compositions of the The main streams of the procedure are compiled, the streams being recorded in the accompanying drawing are. ■

River no.
figure
1

Identification amount composition in

[ml / min] Fe Zn HCl

Organic Charge 1119

More organic

Extract 1119

Regeneration.

solution 114

Regeneration overflow 114

Re-extracted

organic phase

(LA-2). . . . . 224

Loaded organic phase 224

Re-extraction

water 46

Aqueous extract 46

0.29 0.26 0.5

0.08 0.013 0.5

0.014 x 1.70 l6l, 0

2.00 3.40 j6l, 0

0.040 1.20 -

1.10 2.20 *

5.50 4.20. 4.00

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Claims (9)

Patent claims: 1. Process for removing iron present in organic Phases of liquid-liquid extraction is enriched, which contain di- (2-ethylhexyl) phosphoric acid, thereby marked that they can be treated with an acidic directly contacted aqueous solution of chloride ions, from this then by means of an anion exchanger the Iron is extracted so that it can be reused after being freed of iron, by going through the anion exchanger Treatment with water and regenerates the iron from this system in the form of a relatively concentrated aqueous solution removed from ferric chloride. 2. A method for removing iron according to claim 1, characterized in that the acidic aqueous solution of the chloride ions is a mixture of an inorganic Mineral acid and a compatible soluble chloride, preferably a mixture of hydrochloric acid and / or sulfuric acid with sodium and / or calcium chloride. 3. The method according to claims 1 and 2, characterized characterized in that the chloride ion concentration in the acidic aqueous regeneration solution 3 to - 20 - 7 0981871163 9 moles, preferably between 4 to 6 moles. 4. Process according to claims 1 to 3, characterized in that the acid concentration in the aqueous regeneration solution between 2n to 6n, is preferably 4n to 6n. 5. The method according to claims 1 to 4, characterized in that the extraction of the Iron from the regeneration of di- (2-ethylhexyl) phosphoric acid used aqueous solution used anion exchanger an organic solution from a primary and / or secondary and / or tertiary amine and / or a quaternary ammonium base with long alkyl chains, a petroleum alcohol with 8 to 14 carbon atoms and a diluent made from mixtures of hydrocarbons, preferably hydrocarbons of the kerosene type. 6. The method according to claims 1 to 5j thereby characterized in that the concentrations of the amine in the liquid anion exchanger between 5 and 50%, of the fatty alcohol between 0 and 25%, depending on the concentration of iron and other impurities in the liquid regeneration solution. - 21 - 709815/1163 7. Process according to Claims 1 to 6, characterized in that the anion exchanger organic phases formed can be re-extracted or freed of iron for their further use by they are brought into contact with water or dilute salt solutions or acids. 8. The method according to claims 1 to 7 _S, characterized in that the di- (2-äthylhexyl) -phosphoric acid-containing organic phase comes from any liquid-liquid extraction system, which is due to the enrichment of iron and / or other similarly behaving cationic impurities is poisoned, whereby the process can be applied to the total amount of the organic phase or only to a fraction of it _{a in} order to obtain a level of impurities that is compatible with the respective application of the pluid-liquid extraction system. 709815/1163