RU2123976C1 - Method of isolating tributyl phosphate from aqueous solutions - Google Patents

Abstract

FIELD: hydrometallurgy. SUBSTANCE: invention consists in extraction of tributyl phosphate from aqueous solutions with regeneration of tributyl phosphate and extractant. For extraction, nonpolar organic solvent is used, and isolation of tributyl phosphate from extracts is effected via "three-phase" reextraction process consisting in isolation from organic solvent of low-soluble liquid phase of tributyl phosphate compounds with sulfuric acid, ferric chloride or with ferric chloride-hydrochloric acid complex salt. After separation of three-phase system, tributyl phosphate-free light-weight hydrocarbon phase is directed into tributyl phosphate extraction stage; aqueous solution replenished with reextracting substance (sulfuric acid, ferric chloride, or ferric chloride-hydrochloric acid mixture) is used to reextract tributyl phosphate; and heavy organic phase containing tributyl phosphate salts is washed out with water from inorganic acids and salts to produce tributyl phosphate and dilute aqueous reextracting solution. Aqueous reextract, when evaporated, is used to replenish reextracting solution. EFFECT: enabled return of tributyl phosphate into main extraction cycle. 2 ex

Description

 The invention relates to the field of hydrometallurgy, in particular to methods for extracting tributyl phosphate (TBP) from aqueous solutions in order to reduce its loss.

 As you know, the loss of TBP with raffinates reaches 1 g / l, and in some cases more than 10 g / l, as for example in the extraction of PMZ from pulps of nitric acid leaching.

 Various processes have been developed for the purification of aqueous solutions from TBP using flotation, sorption, and extraction processes, as well as combined extraction processes.

 The known method / Brayalovsky B.S., Lutoshkin S.A., Kovalev N.V. "Journal of Applied Chemistry", 1987, 60, No. 1, 209-210 / flotation of TBP from wastewater in the presence of various surfactants depending on the pH of the solutions. This method can significantly reduce the concentration of TBP in solutions. At the same time, the introduction of a surfactant into the solution prevents the further use of TBP in the technological process, as it contributes to the formation of hardly separable emulsions and leads to a violation of the extraction technological mode.

Also known are methods of sorption purification of raffinates from TBP. So, it is proposed / Rushailo E.D., Rodionov A.I., Vaks G.L., Klushin V.N., A.S. 1188104, USSR, publ. in B.I., 1985, No. 40, and Rushailo E.D., Konkova N.A., Rodionov A.I., Klushin V.N., Vaks G.L., Kotov Yu.I. A.S. 1198013, USSR. Publ. in B.I., 1985, N 46 / use ash, clay, activated carbon as TBP sorbents. Processing is carried out at a temperature of 20 ^o C and pH 1-2, with an absorbent consumption of 20 g / l. It was shown that this treatment provides a decrease in the concentration of TBP in solution from 150 to 10 mg / L. It should be noted that despite the simplicity and efficiency of the process, it, just as in the previous case, does not allow the regeneration of tributyl phosphate. In addition, it is not possible to use the process for the extraction of TBP from prefabricated solutions after the extraction of metals from the pulps. Similar disadvantages are inherent in the process / Vax G. L., Yesenina N.V., Rodionov A.I., Rushailo E.D. "Scientific works. GIREDMET", 1984, 125, 88-92 /, in which activated carbon AG-3 and OPU are used as a sorbent under various conditions.

 Closest to the proposed method for extracting TBP is the method / Skrylev L.D., Tkachenko N.V., Sazonova V.F., Purich A.N., ed. St. N 1161474, USSR, Publ. in B.I., 1985, N 22 /, combining extraction of TBP with kerosene, flotation of the emulsion and sorption after-treatment of the solution. This process allows practically quantitative removal of TBP from solutions. The disadvantage of this method is the absence of stages of regeneration of the extractant (kerosene) and tributyl phosphate.

 The invention is directed to the development of a process for the extraction of tributyl phosphate from aqueous solutions, allowing the TBP to be returned to the main extraction stage.

 This object is achieved in that the extraction of TBP from the solutions is carried out by extraction with a non-polar organic solvent, and the separation of TBP from the extracts is carried out using the “three-phase” reextraction process, which consists in the isolation of the poorly soluble liquid phase of TBP compounds with sulfuric acid, iron trichloride or a complex salt from the organic solvent ferric trichloride and hydrochloric acid. After separation of the three-phase system, the light hydrocarbon phase, purified from TBP, is sent to the extraction process of TBP, the aqueous solution after reinforcing the extraction extraction of TBP, the aqueous solution after being reinforced with a stripping substance (sulfuric acid, iron trichloride or its mixture with hydrochloric acid) is used for TBP reextraction and the heavy organic phase containing TBP salts is washed with water from inorganic acids and salts, and tributyl phosphate and an aqueous dilute reextract are obtained s solution. TBP is returned to the main extraction cycle, and the aqueous reextract after evaporation is directed to the operation of reinforcing the reextracting solution.

 The process was carried out as follows.

 Example 1

 Aqueous solutions containing a mixture of calcium, magnesium, sodium, and potassium chlorides with a total salinity of about 200 g / L, as well as sodium nitrate 150 g / L, contaminated with TBP (300 mg / L) were contacted with an extraction dearomatized solvent (RED-1) ( a mixture of saturated hydrocarbons) and with liquid paraffins at a phase ratio of O: B = 1: 1 for 3 to 5 minutes. The distribution coefficient of TBP was determined.

 Within the experimental error, the same results were obtained for both organic solvents: the TBP distribution coefficient during extraction from chloride and nitrate solutions was 800–1000.

To determine the possibilities and conditions for TBP reextraction from hydrocarbon solvents, the concentration in the organic phase was brought to 10-20% and processed accordingly:
1) 10 ml / l sulfuric acid solution;
2) a concentrated solution of ferric trichloride;
3) with a mixture (1: 1) conc. solutions of FeCl ₃ and HCl.

After phase separation, 3 solutions were isolated:
a) the hydrocarbon phase containing 1), 2), 3) 3% TBP, 1% TBP, 0.1% TBP for reextracting solutions, respectively (the data for RED-1 and paraffin are identical);
b) the phase of tributyl phosphate with a TBP content of 50-80%;
c) an aqueous solution with a stripping solution.

 Example 2

 In a continuous mode in a three-stage extractor mixer-settler, the process of extraction of tributyl phosphate from aqueous solutions was carried out.

The process was carried out under the following conditions:
TBP extraction step
- initial aqueous solution: calcium chloride brine with a total salinity of 210 g / l, the content of TBP - 300 mg / l;
- extractant: RED-1 hydrocarbon solvent;
- ratio of phase flows, O: B = 1: 1;
- the number of stages of extraction-1.

TBF stripping step
- stripping solution: mixture of FeCl ₃ (conc): HCl (conc) = 1: 1
- the process with the circulation of the stripping solution;
- the number of stages of stripping - 1.

The stage of washing the heavy phase TBP
- periodic washing of the organic phase from iron
and hydrochloric acid with water (O: B = 1: 1).

As a result of laboratory tests of the process, the following results were obtained:
- the concentration of TBP in the collected solution is 5 mg / l;
- product composition: 88% TBP, 12% RED-1 solvent.

 Thus, the proposed process allows you to remove tributyl phosphate from waste solutions and regenerate TBP. The effluent solutions obtained after extraction (conc. TBP up to 5 mg / l) can be further purified from traces of TBP by sorption on activated carbon or using other methods of purification of solutions.

Claims (1)

 A method of extracting tributyl phosphate from aqueous solutions, including extraction of tributyl phosphate with a non-polar hydrocarbon solvent, characterized in that tributyl phosphate is isolated from the organic solution by treatment with solutions of sulfuric acid, ferric trichloride or a mixture of ferric trichloride and hydrochloric acid, followed by washing the phase of tributyl phosphate from the components.