JPS6026049B2 - Method for removing accumulated iron in liquid-liquid extracted organic phase containing di-2-ethyl-hexyl phosphoric acid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Di-2-ethylhexyl phosphoric acid is a
Cation exchange in valent uranium extraction, separation of uranium and vanadium, separation and purification of rare elements, separation of cobalt and nickel, extraction of beryllium from sulfate solutions, separation of zinc, iron, manganese and cobalt, extraction of zinc, etc. It is used industrially as a body and has many other applications in development.

In all these processes, the fluid treated as an aqueous feedstock usually contains various ionic impurities,
The most common metal is iron.

The affinity of di-2-ethyl-hexyl phosphate for iron is so high that it can be quantitatively extracted even at very low concentrations of iron, forming a polymer that polymerizes in the organic phase, with a polymer molecular weight of 200. The height is also high. This phenomenon ultimately results in a significant reduction in the loading capacity of the cation exchanger and also in a considerable increase in the viscosity in the organic phase, making it difficult to use it as an extractant in a large number of possible applications or It becomes unavailable. It is well known that there are two possible ways to exclude iron from these organic phases.

The first method is to wash the organic phase with a strongly alkaline solution of hydroxide or sodium carbonate.

This treatment causes the polymer to split to form ferric hydroxide and the sodium salt of di-2-ethyl-hexyl phosphate. Due to the presence of ferric hydroxide precipitation in the aqueous phase and the high degree of disassociation of the sodium salt from the acid,
The car-along and solubility of di-2-ethylhexyl phosphoric acid has become so high that it is economically difficult to use it on an industrial scale. The second method is to wash the organic phase with an aqueous solution of aM hydrochloric acid. This treatment also splits the polymer by formation of anionic key body CL4Fe from ferric ions in the chloride medium, replacing cation exchange between organic bait ions and H+ ions of the aqueous phase. do. This process is not always economically attractive due to the high consumption of acid required. In this second method, hydrochloric acid consumption is determined by the balance existing between the two phases during the process with respect to ferric ions, which requires purification of the acidic aqueous solution when a given iron concentration is reached. However, this represents a small fraction of the acid equivalents utilized, thus resulting in a 10-2 fraction of the acid consumption.

The present invention eliminates the iron accumulated in the organic phase containing di-2-ethyl-hexyl phosphate by an acidic aqueous solution containing chloride ions, and then sequentially treats the regenerant solution by removing the iron for reuse. Regarding how to. Therefore, the method of the present invention consists of the following three steps.

In the first step, the organic phase containing di-2-ethylhexyl phosphate played by iron is removed from the F between the aqueous phase and the organic phase.
Regeneration of the organic phase is carried out by contacting it with an acidic solution containing chloride ions at a concentration that results in an exchange of H+ for eH+ ions.

In a second stage, the regeneration fluid of the previous stage is regenerated by contacting it with an anionic ion exchanger in such a way that after displacement of a stoichiometric amount of hydrochloric acid equal to the rejected iron, the regeneration fluid can be reused in the first stage. Extracts iron contained in fluid.

In the third stage, iron is re-extracted from the anionic exchanger-containing organic phase from the previous stage so that the iron-free organic phase is recycled for reuse in the second stage. . Briefly, iron is introduced into two intermediate vehicles (Ve) with an acidic solution of chloride ions and an organic solution of an anionic exchanger.
hicles) from the di-2-ethylhexyl phosphate-containing organic phase to water, and this entire process, which is the subject of the present invention, provides only a consumption of hydrochloric acid equal to the iron excluded, Water needed to remove ions from the system is rejected.

In the first or regeneration stage, the reactor is one of cation exchange reactions, which can be simply expressed as the following balanced equation. R3Fe (〇), 10 10 (aq), 14 CI-
(aq) This day (0) 10CI4Fe- (aq) RH indicates di-2-ethylhexyl phosphoric acid.

Thus, in principle, the regenerant can be either a mixture of inorganic minerals and soluble chloride, hydrochloric acid used alone or mixed with sodium chloride or calcium chloride, and sulfuric acid used in combination with sodium chloride or calcium chloride. It is actually preferable to use it in combination with The optimum proportion of these agents in the regeneration liquid clearly depends on the concentration of di-2-ethyl-hexyl phosphate in the organic phase and the level of residual iron desired in the application at hand. For the widely used concentration of 10% V/V in kerosene, the optimum concentration of hydrochloric acid in the regeneration liquid was found to be 4-6 molar.

The regeneration of di-2-ethylhexyl phosphoric acid can be carried out in any extraction apparatus with a solvent, preferably in a precipitation mixer.

A device of this type was used continuously in the applicant's tests. The amount of time or contact time required to achieve equilibrium depends on the concentration and degree of concentration in the organic and aqueous phases. In all cases this time is less than 10 minutes, and mostly less than 3 minutes. Phase separation presents no difficulties.

When a regenerant in the form of 5.8 M hydrochloric acid is simply brought into contact with an organic phase of di-2-ethyl-hexyl phosphoric acid 10% V/V with appropriate flow rate adjustment, the rejection rate of iron in the organic phase is +90%, resulting in an organic phase containing iron in an amount of less than 150 sail/1.

Temperatures compatible with this method may vary between loo-50°C.

The concentration of D-speck HPA in the organic phase can vary between 1%-50%V.

The concentration of chloride ions in the regenerant may vary between 0.1-12M and 4.0-6. Best results are obtained with dish M.

Another objective of the process of the present invention is to eliminate iron for recycling from the aqueous chemicals used in the regeneration of di-2-ethylhexyl phosphate.

To extract the iron in the second cycle, an organic phase consisting of three components is used: an extractant, a political agent and a diluent.
The extractant belongs to the amino group and may be primary, secondary or tertiary, or has long alkyl groups, is only slightly soluble in water and has a molecular weight of more than 200. It may also be based on quaternary ammonium.

The modifier, which is the second component of the organic phase, has the purpose of facilitating phase separation during extraction.

Alcohols containing 8-14 carbon atoms produce the desired results. The third component, the diluent, acts as a carrier for the other two drugs and reduces the viscosity of the medium.

Hydrocarbons or hydrocarbon mixtures such as those obtained in fractionation steps in petroleum distillation can be used. The fixation of iron on the extractant is based on the fact that this element forms anionic chlorinated rust bodies in solutions of chloride ions according to the following equilibrium equation:

4CI-+Fe32CI4Fe- The extraction of iron is carried out by ion exchange between the chloride of the family/compound and the ion body of iron.

In the case of secondary amine chloride (R2 ratio NCI), the equilibrium equation can be shown as: R2NQCI+CI4Fe
-R2NH2CI4Fe+CI-Fe30 and CI
Shifting this reaction to the right or extraction direction to the extent that it is produced by the concentration of - depends on all of the CI - intervening in the constant of the formation of anionic rust bodies of iron.

The extraction of iron can be carried out in any extraction device using a solvent, preferably a settling mixer.

A device of this type was used continuously in the tests of the invention. The trunk or contact time required to achieve equilibrium depends on the concentration in the organic and aqueous phases and the degree of entrainment.

In any case, this time should be no more than 10 minutes and should not exceed 2-5 minutes.
Minutes are king. Phase separation is not difficult when modifiers are present in the organic phase.

By simply bringing the amine-containing organic phase into contact with the regenerant by properly adjusting the flow ratio between the two, the iron removal rate from the regenerant achieved reaches 95%, and the iron concentration of the aqueous extract decreases. The score was below 9/1 for 40 pairs.

The temperature compatible with this process is 1oo-50oC. Depending on the iron and chloride concentrations in the regenerant, the amine concentration in the organic phase can be 1-50% and the aliphatic alcohol concentration 0-25%.

The re-extraction of iron from the amine-containing organic phase is carried out with water, based on the disassociation of the anionic enantiomer of iron CI4Fe- in the absence of chloride ions.

Depending on the organic phase and water flow ratio, more or less concentrated secondary chloride
An iron solution is obtained with some evolution of the organic phase. After re-extraction, the organic phase is virtually iron-free and can therefore be recycled into the process.

Regenerant (hydrochloric acid) losses when using the method of the invention are reduced to the sum of the chemically theoretical consumption corresponding to iron and the small amount of purification required to maintain the balance of water in the system. Ru.

The method of the present invention allows the formation of other ions, such as chromium, aluminum, etc., which form anionic key bodies in a chloride environment.
- Can also be used to regenerate ethylhexyl phosphoric acid.
The invention will now be illustrated by examples, but the invention is not limited thereby. Example 1 D performed the HPA regeneration test.

An organic phase having the following composition was prepared. Group D HPA
: 10% V/V petroleum (product of Campania Arendataria Monopolios de Vetroleo) : 90% V
/V Iron was added to this organic phase at a concentration of 0.33 total/1.

The organic phase is then treated in a single step with hydrochloric acid 5. It was brought into contact with a solution of Insect M. The ratio of organic phase flow to aqueous phase flow is 1
It was 0. The results were as follows.

Iron in the organic phase: 0.11% Iron in the aqueous phase: 2.1% Example 2 The regenerant concentrations listed were used by D for regeneration of HPA.

The organic phase had the same composition as used in Example 1.

The iron concentration in the organic phase, the regenerant concentration, and the ratio of organic phase flow to aqueous phase flow were as shown in the table.

Both phases were contacted in a single step and the following results were obtained.

Example 3 D used all of the regenerant compositions listed below for regeneration of HPA.

The organic phase had the same composition as in the previous example.

The concentration of iron in the organic phase, the composition of the regeneration solution, and the ratio of organic phase flow to aqueous phase flow were as follows.

Both phases were contacted in a single step and the following results were obtained.

Example 4 ○ Iron was removed from the liquid for regeneration of spotty HPA.

The composition of the organic phase was as follows.

Amberlite-LA-2 (commercially available secondary amine) 15% isodecanol (ls
odecanol) 6% Petroleum (Campania Arendataliamo/Polios de Vetroleo product) 79% The above organic phase was contacted in a single step with the regenerated effluent from the D-stained HPA.

The iron-containing organic phase was re-extracted with water in a single step.
The concentration of iron in the effluent from regeneration, the ratio of organic phase flow to aqueous phase flow in extraction and reextraction was as follows:

The following results were obtained.

Example 5 This example was carried out continuously on a medium scale test, in Group D H.
The results of PA regeneration and iron removal from the effluent from the regeneration are summarized.

In the accompanying diagram, the stages of the process are indicated by Roman numerals.
The main flow is indicated by Arabic numerals. In these tests, the process consisted of the following steps.

Regeneration of Group D HPA ILA
Re-extraction with water The organic extract from m previous extraction steps was available.

The organic extract had the following composition. iron
0.29g/l zinc
0.2 thigh/l Hcl acid
<0.5g/1 The regenerant used had a concentration of 4. It was hydrochloric acid with a rule of M/1.

The flow rates and compositions of the main streams of the process shown in the accompanying figures were as follows.

[Brief explanation of the drawing]

The accompanying drawings illustrate the stages and main flows of the process according to the invention. 1,0,m...Process stage, 1-8...
・A royal flow.

Claims (1)

[Scope of Claims] 1. The liquid-liquid extracted organic phase containing di-2-ethyl-hexyl phosphoric acid is directly contacted with an acidic aqueous solution of chloride ions to remove iron accumulated in the organic phase. and then acting on the acidic aqueous solution of chloride ions with an anionic ion exchanger that extracts the iron and renders the acidic aqueous solution iron-free for reuse, and the anionic exchanger a liquid-liquid extracted organic compound containing di-2-ethyl-hexyl phosphoric acid, characterized in that the iron is purified from the system in the form of a relatively concentrated aqueous ferric chloride solution by regenerating the iron by treatment with water. A method of removing iron accumulated in the phase. 2. The method according to claim 1, wherein the acidic aqueous solution of chloride ions comprises a mixture of an inorganic mineral acid and compatible soluble chlorides, preferably hydrochloric acid and/or sulfuric acid and chloride for economic reasons. A method consisting of sodium and/or calcium chloride. 3. The method according to claim 1 or 2, wherein the chloride ion concentration in the acidic aqueous solution as the regenerant is in the range of 3-9 mol, preferably 4-6 mol. 4. The method according to any one of claims 1, 2, and 3, wherein the acidic concentration in the aqueous solution of the chloride ion regenerant is in the range of 2-6 normal, preferably 4-6 normal. 5. In the method according to claim 1, 2, 3 or 4, the anionic exchanger used for extracting iron from the aqueous solution used for regenerating di-2-ethyl-hexyl phosphoric acid is those based on primary amines and/or secondary amines and/or tertiary amines and/or quaternary ammoniums with long alkyl chains; aliphatic alcohols having 8-14 carbon atoms; and hydrocarbon mixtures, especially The method is formed with an organic solution composed of a diluent, which belongs to the kerosene type. 6. The method according to claim 1 or 5, wherein the amine concentration in the anionic exchanger fluid is between 5 and 50, depending on the concentration of iron and other impurities in the aqueous regenerant solution.
% and the aliphatic alcohol concentration is 0-25%. 7. In the method according to any one of claims 1 to 6, the organic phase formed by the anionic exchanger is subsequently reused by contacting with water or dilute salt water or an acidic solution. How iron is extracted or removed.