RU2260063C2 - Extractant for extracting metals and method for producing it - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: extractant has bi-phosphorus acid and additionally has tri-phosphate with relation of said components (0,5-1,25):1. Method for producing extractant includes adding to 2-ethylhexanole of chlorine oxide of phosphorus with their relation (4,5-5,1):2,0, and with parameters determined by reaching fullness of passing of reaction, after that reaction mixture is exposed until full removal of formed chlorine hydrogen, then to received mixture 1 mole of water is added, mixture is exposed to full hydrolysis. Then mixture is washed ad water layer is separated from organic remainder, containing said bi-phosphoric acid and tri-phosphate.

EFFECT: higher efficiency.

2 cl, 1 dwg, 2 tbl, 4 ex

Description

The invention relates to the field of chemistry of organophosphorus compounds and hydrometallurgy. It relates to a method of producing an extractant - synergistic mixture:

Tris (2-ethylhexyl) phosphate (T-2)

and di- (2-ethylhexyl) phosphoric acid (D-2)

in a molar ratio (0.5-1.25): 1.0 and the method of its use in the hydrometallurgy of non-ferrous, rare, rare-earth, uranium metals and in the processing of spent nuclear fuel.

Organophosphorus extractants are known: tributyl phosphate (TBP), (C ₄ H ₉ O) ₃ PO and di- (2-ethylhexyl) phosphoric acid (D2EHPA) (D-2), which are widely used in hydrometallurgy [1-3].

The closest analogue of the invention for the combination of essential features, the purpose of the extractant and the method of its production is [7] SU 480716 (IPC C 01 F 9/08, publ. 03.11.1975), which describes an extractant for the extraction of metals containing di- (2 -ethylhexyl) phosphoric acid and a method for producing an extractant for the extraction of metals containing di- (2-ethylhexyl) phosphoric acid, with the addition of phosphorus oxychloride to the alcohol. However, the extractant obtained by this method does not contain trialkyl phosphate, which affects the relatively low capacity of the recoverable metal. In addition, the method is low-tech.

The disadvantage is the need for preliminary obtaining the individual components of TBP and D-2 in separate chemical processes, as well as a low distribution coefficient and low capacity for the recoverable element.

The disadvantages of the prototype are eliminated by the invention.

The technical result of the invention is the development of a one-stage technological method for producing a synergistic extractant and an increase in the separation coefficient and capacity for the extracted metal by 20-25%. The technical result is achieved by the fact that the extractant for the extraction of metals containing di- (2-ethylhexyl) phosphoric acid additionally contains tris- (2-ethylhexyl) phosphate at a ratio of components (0.5-1.25): 1 in moles, as well as the fact that It is used for the extraction of non-ferrous, rare and rare-earth metals and uranium. Also, a method for producing an extractant for the extraction of metals containing di- (2-ethylhexyl) phosphoric acid, including the addition of phosphorus oxychloride to the alcohol and characterized in that phosphorus oxychloride is added to 2-ethylhexanol at a ratio of (4.5-5.1): 2.0, and at the parameters determined by the achievement of the completeness of the reaction, after which the reaction mixture is maintained until the hydrogen chloride formed is completely removed, then 1 mol of water is added to the resulting mixture, the mixture is kept until hydrolysis is complete, then the mixture is washed and the aqueous layer from the organic residue containing di- (2-ethylhexyl) phosphoric acid and tris- (2-ethylhexyl) phosphate is removed, while phosphorus oxychloride is added to 2-ethylhexanol at a pressure of 50-70 mm Hg, temperature (10 ± 5) ° C for 1-1.5 hours; the resulting reaction mixture is maintained at a pressure of 50-70 mm Hg, temperature (10 ± 5) ° C for 2-3 hours; the reaction mixture after exposure at a temperature of (10 ± 5) ° C is maintained at a temperature of 45-55 ° C for 2-3 hours; washing the reaction mixture is carried out with a salt reagent.

After washing the reaction mixture with a 10-20% sodium chloride solution and separating the aqueous layer in the organic residue, a synergistic extractant (T-2: D-2) is obtained in a molar ratio (0.5-1.25): 1.0. Yield (90-95)%. The finished product containing 1-5% mono- (2-ethylhexyl) phosphoric acid is used in the extraction process.

Obtaining the extractant is carried out by the interaction of 2-ethylhexanol with phosphorus oxychloride according to the equation:

A characteristic feature of the synthesis of synergistic extractant is that by adjusting the ratio in moles of 2-ethylhexanol and phosphorus oxychloride, it is possible to obtain a synergistic mixture of T-2: D-2 of various compositions in moles (1: 1), (1: 2), (1 : 3). This is important in the sense that, for example, for the extraction separation of Co and Ni, a mixture of a 10-30% solution of D-2 and a 5% solution of T-2 in kerosene is used (p. 166 [6]). When extracting vanadium, a mixture of a 6% solution of D-2 and a 3% solution of T-2 in kerosene is used, separating it from uranium, iron, and molybdenum (p. 291 [6]). The extraction separation of uranium, thorium, rare earths, iron, calcium, aluminum is successfully carried out with the extractant 0.1 M D-2 and 0.1 M TBP in kerosene (p. 299 [6]). Using a synergistic mixture of T-2: D-2 in a ratio of 0.1 M in kerosene allows achieving similar results.

When conducting comparative experiments on extraction used D-2, TBP (analogues), a synergistic mixture of D-2 + TBP (p. 257 [6]) and a synergistic mixture of D-2 + T-2 (subject of the invention). Extractant solutions were prepared using KO-30 lighting kerosene (organic phase).

0.8-30 г/л (водная фаза). В процессе исследований определяли извлечение урана и разделение уран/железо (III).For the extraction of uranium, solutions of the following composition were used: H ₂ SO ₄ 0.1-300 g / l, HNO ₃ 0-30 g / l, Fe ³⁺ 0-10 g / l,

0.8-30 g / l (aqueous phase). In the process of research, the extraction of uranium and the separation of uranium / iron (III) were determined.

Extraction was performed in countercurrent mode in a 6-chamber mixer-settler (the volume of the mixing chamber was 0.5 l, the settling chamber was 2.5 l, and the productivity by the sum of the phases in all cases was 10.5 l / h). In all cases, the phase ratio is B: 0 = 4: 3.

The extraction isotherms were recorded by the cross current method. The rate of phase separation was determined by the rate of release of the aqueous phase after stopping the stirrer.

The uranium extraction isotherms are shown in the drawing, the concentration of uranium and iron (III) in the saturated organic phase, as well as the delamination rate are presented in table 1.

Table 1. Some technological indicators of uranium extraction by analog, prototype and (T-2 - D-2 in a ratio of 1: 1) No. Extractant U in us. RP, g / l Fe (III) in us. RP, g / l Coeff. U / Fe Speed mm / min The third phase,% 1 0.14 M D-2 8.6 39 2.0 · 10 ¹ 39 out 2 0.14 M D-2 + 0.14 M TBF 15.5 0.02 7.1 · 10 ⁴ 32 out 3 0.14 M D-2 + 0.07 M T-2 15.2 3.9 3.6 · 10 ² 35 out 4 0.14 M D-2 + 0.14 M T-2 20.3 0.02 9.4 · 10 ⁴ 32 out

As follows from the data of the drawing and table 1, in binary mixtures with D-2 tris- (2-ethylhexyl) phosphate significantly improves the technological characteristics of the synergistic extractant - the capacity of the organic phase in uranium increases by 20-30%, the U / Fe separation coefficient also increases by 20%, in addition, delamination improves, the formation of the "third" phase during extraction is not observed in any of these systems.

The methodology and results of experiments on the re-extraction of uranium and the production of U ₂ About ₃ .

Uranium from saturated samples of the extractant was re-extracted with 10% (NH ₄ ) ₂ CO ₃ + 3% NH ₄ NO ₃ (O: B = 3: 1, T = 35 ° C, τ = 1 hour). After reextraction, the phases were separated in a separatory funnel, crystals of ammonium uranyltricarbonate (AUTC) were separated from the mother liquor and washed with a reextractor solution, which was previously saturated with uranyl nitrate to equilibrium concentration.

The degree of reextraction was calculated by the residual concentration of uranium in the organic phase. For all studied extractants, the values of the degree of reextraction were in the range of 99.2-99.6%.

The washed AUTC samples were calcined at Т = 700 ° С (τ = 1 hour), the obtained uranium oxide was analyzed for phosphorus and iron content, since these elements are the main limiting impurities in U ₃ O ₈ - iron is always present in significant quantities in industrial commodity solutions, the organophosphorus extractants themselves can also be a source of phosphorus. The results of the analysis of samples of oxide-oxide are presented in table 2.

Table 2. The content of the main limiting impurities in uranium oxide. Component TU requirements Sample Content Phosphorus,% <0-08 <0.01 Iron,% <0-03 <0.01

Thus, the tested extractants provide U ₃ O _{8 to the} desired degree of purity. Tris-2-ethylhexylphosphate in its technological qualities significantly exceeds TBP. The mixed extractant D-2 + T-2 has a uranium capacity of 20-30% more than D-2 + TBP, as well as increased extraction selectivity. The delamination rate is no worse than in a system with D-2 + TBP.

In all cases, as a result of re-extraction, uranium oxide-oxide of the required degree of purity is obtained for the main limited impurities.

The extraction separation of cobalt and nickel from sulfuric acid solutions was carried out with a synergistic mixture of D-2 + TBP = 10-30%: 5% prototype in kerosene (p. 166 [6]). The initial sulfuric acid solutions had a pH of 5-6. The ratio of Co / Ni in the aqueous phase is 1: 1. Extraction was carried out at a temperature of 60 ° C. A 95.7% cobalt recovery was obtained with a Co / Ni ratio of 17.4 in the organic phase. Using the synergistic mixture T-2: D-2 = 0.5-1.0 in moles (or a 4% solution of T-2 and a 10% solution of D-2) in kerosene made it possible to achieve Co / Ni separation of 18.6 when 96% of cobalt was recovered in the organic phase .

When extracting vanadium from sludges of iron foundry and petroleum ash, uranium-vanadium ores, titanium-ferrous magnesites, sulfate solutions are obtained. As a result of heating them with iron powder, vanadium passes into a 4-valence state.

Extraction is carried out in six stages of a sump mixer, using a solution of 6% D-2 and 3% TBP in kerosene (p. 291 [6]) (prototype). Reextraction is carried out in 4 steps with sulfuric acid concentration of 140 g / l at a temperature of 38-50 ° C. Reextract contains 55-65 g / l V ₂ O ₅ . Vanadium is converted to sodium hexavanadate (red cake), which is converted by calcination to 98% vanadium pentoxide.

The use of the T-2 - D-2 synergistic mixture in this process gives similar results.

Example 1. Synthesis of synergistic extractant T-2-D-2 (ratio 1: 1)

150 g of 2-ethylhexanol are charged into a 4-necked 0.5 L glass reactor with a stirrer, a thermometer, a dropping funnel, a bubbler of air passed through a tube with phosphoric anhydride and a nozzle for connecting a vacuum. The reactor is cooled to a temperature of + 5 ° C and with stirring and blowing dry air through a bubbler under a vacuum of 50-70 mm Hg. 36.6 ml of phosphorus oxychloride are added over an hour. Upon completion of the addition, the reaction mixture was kept under the same conditions for 2 hours, then the mass temperature was raised to 45-55 ° C and kept under these conditions for another 2 hours.

After that, 10 ml of water are added to the reactor at a temperature of 45-55 ° C and incubated for 1 hour. The reaction mixture is cooled to a temperature of 20-25 ° C, 100 ml of a 10% aqueous NaCl solution are added, stirred and separated after peeling. The organic residue was washed with 100 ml of water and separated.

In the organic residue, 145 g of a synergistic mixture of tris- (2-hexylethyl) phosphate and di- (2-ethylhexyl) phosphoric acid.

Yield 95.7%.

Analysis: D-2 - 37.5%, mono-2EHPA - 2.8%, 2-ethylhexanol - 5.2%, tris- (2-ethylhexyl) phosphate - 54.5%.

The ratio: (T-2: D-2) = (0.11: 0.1) g / mol.

Chem. NMR shifts: T-2 δ ³¹ P - 1.200 ppm; D-2 - δ ³¹ P - 0.7 ppm; mono-2EGFK δ ³¹ P - (-10.79 ppm)

Example 2. Synthesis of synergistic extractant T-2 ÷ D-2 (ratio 0.5: 1).

The synthesis was carried out on a setup as described in Example 1. The reagent ratio in moles was 2-ethylhexanol: phosphorus oxychloride 4.66: 2. 150 g of 2-ethylhexanol are charged into the reactor, cooled to a temperature of + 5 ° C and with stirring and blowing dry air through a bubbler, under a vacuum of 50-70 mm RT. Art. 45 ml of phosphorus oxychloride are added over 1 hour. Upon completion of the addition, the reaction mixture was kept under the same conditions for 3 hours, then the temperature was raised to 45-55 ° C and held for another 2 hours under these conditions. After that, 10 ml of water are gradually added to the reactor at a temperature of 45-55 ° C and held for 1 hour. After cooling to a temperature of 20-25 ° C, the reaction mixture is washed (2 × 50 ml) with 10% NCl solution, then (2 × 50 ml ) 5% solution of ammonium bicarbonate and water. After keeping the organic residue in vacuum at a temperature of 60-80 ° C for 1.5-2 hours, a synergistic mixture of the composition T-2: D-2 = 0.5: 1 in moles is obtained, yield 162 g (91%).

Analysis: D-2 58.1%, T-2 32%, α-ethylhexanol 3.2%, mono-2HPFA 4.7%, 2-ethylhexyl chloride 1.9%.

Chemical shifts ³¹ P correspond to example 1.

Example 3. Extraction of uranium using extractants

Extraction was carried out in a 6-chamber extractor as described above. The solutions were prepared on illuminating kerosene brand "KO-30" (organic phase).

Uranium was extracted from an industrial solution of the following composition: U - 15/8 g / l, Fe ³⁺ - 1.45 g / l, H ₂ SO ₄ - 125 g / l, HNO ₃ - 12 g / l (aqueous phase).

In the process of research, the extraction of uranium and the separation of uranium / iron III were determined.

a) Extractant 0.14 M D2EGFK (analog)

Saturated extractant - 8.65 g / l U, 48 mg / l Fe ³⁺ , raffinate - 9.3 g / l U. Extraction of U in RP - 41.1%, separation coefficient U / Fe = 19.8.

b) Extractant 0.14 M D2EGFK + 0.14 M TBF (prototype)

Saturated extractant - 15.6 g / l U, 0.04 mg / l Fe ³⁺ , raffinate -4.11 g / l U. Extraction of U in RP - 74%, separation coefficient U / Fe = 35800

c) Extractant 0.14 M D2EGFK + 0.14 M T2EGF (subject of invention).

Saturated extractant - 20.6 g / l U, 0.02 mg / l Fe ³⁺ , raffinate - 0.34 g / l U. Extraction of U in RP - 97.8%, separation coefficient U / Fe = 94600.

Example 4. The extraction separation of cobalt and Nickel from sulfate solutions was carried out with a synergistic mixture of D-2: TBP = (10-30)%: 4% in kerosene (prototype) in comparison with a synergistic mixture of D-2: T-2 (subject of the invention) .

The initial sulfate solutions had a pH of 5-6. The ratio of Co / Ni in the aqueous phase is 1: 1. Extraction was carried out at a temperature of 60 ° C. Obtained 95.7%, cobalt recovery at a ratio in RP Co / Ni = 17.4.

Using the synergistic mixture D-2: T-2 = (0.5: 1) in moles (or a 10% solution of D-2 and a 4% solution of T-2) in kerosene made it possible to achieve the separation of Co / Ni = 20.6 in RP, when cobalt is extracted 96% in OF.

Thus, the present invention has several advantages. Firstly, the extractant provides high metal recovery in the organic phase and a higher separation coefficient of metals, which represents economic profitability.

In addition, the method of producing the extractant is one-stage, which simplifies its production technology and gives a significant economic effect.

Sources of information

1. Burger L.L., Wagner R.M. Chem. Engng. Data Series, 3, 2, 310 (1958).

2. A.S. USSR 202101, 09/14/1967.

3. “Modern radiochemistry”, V. Vdovenko M .: Atomizdat, 1969, p. 106.

4. Coleman C.F., Blake C.A., Brown K.B., Talanta. 9, 3, 297 (1962).

5. "Modern radiochemistry", V. Vdovenko M .: Atomizdat, 1969, p. 116].

6. G.M. Ritchie, A.V. Ashbrook, "Extraction" M.: Metallurgy, 1983, p. 166, 257, 291, 299.

7. Bliznyuk N.K., Protasova L.D., Klopkova R.S., SU 480716 (IPC С01 F 9/08, published 03.11.1975).

Claims (7)

1. An extractant for the extraction of metals containing di- (2-ethylhexyl) phosphoric acid, characterized in that it additionally contains tris- (2-ethylhexyl) phosphate at a ratio of components (0.5-1.25): 1.0 in moles. 2. The extractant according to claim 1, characterized in that it is used for the extraction of non-ferrous, rare, rare earth metals and uranium. 3. A method of producing an extractant for the extraction of metals containing di- (2-ethylhexyl) phosphoric acid, comprising adding phosphorus oxychloride to an alcohol, characterized in that phosphorus oxychloride is added to 2-ethylhexanol at a ratio of (4.5-5.1): 2.0 and parameters determined by the completion of the reaction, after which the reaction mixture is maintained until the resulting hydrogen chloride is completely removed, then 1 mol of water is added to the resulting mixture, the mixture is kept until complete hydrolysis, then the mixture is washed and the aqueous mixture is separated the second layer from the organic residue containing di- (2-ethylhexyl) phosphoric acid and tris- (2-ethylhexyl) phosphate. 4. The method according to claim 3, characterized in that phosphorus oxychloride is added to 2-ethylhexanol at a pressure of 50-70 mm Hg, temperature (10 ± 5) ° C for 1-1.5 hours 5. The method according to claim 4, characterized in that the resulting reaction mixture is maintained at a pressure of 50-70 mm Hg. and temperature (10 ± 5) ° С for 2-3 hours 6. The method according to claim 5, characterized in that the reaction mixture after exposure at a temperature of (10 ± 5) ° C is maintained at a temperature of (45-55) ° C for 2-3 hours 7. The method according to any one of claims 3 to 6, characterized in that the washing of the reaction mixture is carried out with a salt reagent.

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