Extraction of rare earth elements from aqueous solutions

 

(57) Abstract:

The method relates to the field of extraction of substances organic extractants from aqueous solutions, such as rare earth elements (REE), and can be used in ferrous and nonferrous metallurgy. How is that as an extractant use technical lubricant, in its composition contains, wt%: oleic acid 10 - 12, triethanolamin of 4.5 - 6.0, engine oil (inert diluent) - else, and extraction is carried out in the interval 0 < pH < 10 a continuous regulation of the optimal pH for a period of not more than two hours. The method allows to increase the degree of REE extraction and separation. table 1.

The invention relates to the extraction of substances organic extractants from aqueous solutions and can be used in ferrous and nonferrous metallurgy, waste treatment and metallurgical industries, as well as for cleaning mine and mine water, industrial sewage.

Known methods of REE extraction extraction esters of phosphorus-containing organic acids (Chemistry and technology of rare and scattered elements, ch. II. Ed. Corr.-Corr. The USSR Academy of Sciences K. A. Bolshakova, M.: Higher school, 1976, S. 128 - 135). the you.

Closest to the invention is the extraction of REE carboxylic acids (CnH2n-1COOH) at pH of 2.0 to 3.5. Most commonly used technical mixture of acids (C7- C9), naphthenic acids, C12-C13). For greater efficiency of separation of the extractant injected alkali, vysalivatel and complexing agents. Best results are obtained with the introduction of nitryltriacetic acid at a pH of 5.5 to 6.0 (Chemistry and technology of rare and scattered elements, ch. II, Ed. Corr. -Corr. The USSR Academy of Sciences K. A. Bolshakova. M.: Higher school, 1976, S. 137 - 138).

The disadvantages of the method are the low efficiency of extraction, as forming connections is much more difficult to dissolve in the organic phase, low partition coefficients, narrow intervals the pH of the extraction.

The objective of the invention is to create an effective, inexpensive and selective way of REE extraction from aqueous solutions using less volatile and readily available extractant.

The technical result that can be achieved by carrying out the invention, lies in the high degree of REE extraction from aqueous solutions, with the possibility of their separation, while the efficiency and safety of the process.

Oleic acid to 10 - 12

Triethanolamine - 4,5 - 6,0

Engine oil (inert diluent) - Rest

and extraction is carried out in the interval 0<pH6H2O, ErCl36H2O and YbCl36H2O mark H. h

The extractant was added to aqueous solution of salts in an amount to provide the formation of water-oil emulsions with a content of 5 wt.% lubrication SP-3.

The extraction was carried out at different pH values of the solutions. During the extraction the pH of the solution was changed, therefore, was carried out by regulating the pH to a specified initial value acid, H2SO4or alkali NaOH.Regulation constant pH in the extraction process was carried out within 0,10 - 2,00 hours; after this time further acid-base characteristics of the solution was changed slightly. The pH in the solutions was controlled by a pH-meter.

Through a day or more after the extraction of the oil phase was separated from the aqueous phase, whereupon the latter missed the new method.

The difference between the concentrations of metals in the initial solution and in the filtered aqueous phase was determined by the concentration of the metal in the organic oil phase.

Extraction was investigated at room temperature.

Example 1 (table, experiment 1). Extraction was carried out from aqueous solution LaCl3when the concentration of the initial solution CRef= 545 mg/DM3and pHRef= 5.5 in the interval 0<pH<10.4correspond to the intervals of pH 1 to 3 and pH 6 - 7.

The minimum concentration of lanthanum in the raffinate 1 mg/DM3obtained in the range of pH 6 to 10.

At a pH of 8 to 10 is formed of a powdery residue.

At pH 4 to 7, the extraction time is 2 hours , at 4>pH>7 the extraction time of 720 hours

Example 2 (table, experiment 2). Extraction was carried out from aqueous solution PrCl3with the concentration of the original solution CRef= 352 mg/DM3and pHRef5,1 in the interval 0<pH<9.

The minimum concentration of praseodymium in the raffinate 1.6 mg/DM3obtained at pH 6 - 9.

At pH 8 - 9 forms a powdery residue.

the.1.

Extraction was carried out from aqueous solution NdCl3when the concentration of the initial solution CRef= 386 mg/DM3and pHRef1.0 in the interval 0<pH<8.

The minimum concentration of neodymium in the raffinate 253 mg/DM3obtained at pH 6.

At pH 8 is formed powdery residue.

At pH 1 to 8, the extraction time is 2 hours

Experience 3.2.

Extraction was carried out from aqueous solution NdCl3when the concentration of the initial solution CRef= 193 mg/DM3and pHRef4.2 in the range of 1<pH<8.

The minimum concentration of neodymium in the raffinate 6 mg/DM3obtained at pH 5.

At pH 8 is formed powdery residue.

At pH 6 extraction for 2 hours, at pH 3 and 7 - time extraction 551 PM

Experience 3.3.

Extraction was carried out from aqueous solution NdCl3when the concentration of the initial solution CRef=247 mg/DM3and pHRef= 5,2 in the range of pH 1 - 8.

The maximum extraction K = 1,5104correspond to pH 6 - 7.

Myaskovsky sediment.

At pH 4 to 6, the extraction time of 2 h, at pH 1 and 8, the extraction time is 360 hours

From the data of experience 3 we can draw the following conclusions:

the extraction efficiency increases with increasing pH of the solution in the extraction process;

lowering pHRefinitial solution the extraction time is reduced.

Example 4 (table, experiments 4.1, 2, 3, 4).

Experience 4.1.

The extraction was carried out from aqueous solution SmCl3when the concentration of the initial solution CRef= 114 mg/DM3and pHRef= 5.2 in the interval 0<pH<9.8correspond to the values of pH 3 and pH 7.

The minimum concentration of samarium in the raffinate is less than 10-4mg/DM3obtained at pH 7 to 9. This value is determined by the accuracy of ongoing weight analysis.

At pH 8 - 9 obtained powdery residue.

At pH 4 to 6, the extraction time of 24 hours, at a pH of 1 to 3 and pH 7 - 9 - extraction time 480 hours

Experience 4.2.

The extraction was carried out from aqueous solution Sm2(SO4)3when the concentration of the initial solution CRef= 941 mg/DM3and pHRef= 3,2 in the range of 1<pH<8.3cootware pH 8.

PI pH 8 obtained powdery residue.

At pH 6 to 8, the extraction time of 15 min, with 1 - 5 the extraction time is 2 hours

Experience 4.3.

The extraction was carried out from aqueous solution Sm2(O4)3when the concentration of the initial solution CRef= 1008 mg/DM3and pHRef5,3 in the interval 0<pH<8.3correspond to the values of pH 3 and pH 7.

The minimum concentration of samarium in the raffinate 84 mg/DM3obtained at pH 8.

At pH 8 is formed powdery residue.

At pH 1 to 8, the extraction time is 2 hours

Experience 4.4.

The extraction was carried out from an aqueous solution of Sm(NO3)3when the concentration of the initial solution CRef= 841 mg/DM3and pHRef5,3 in the interval 0<pH<10.5correspond to the values of pH 4 and pH 8.

The minimum concentration of samarium in the raffinate 3 mg/DM3obtained at pH 8.

At pH 6 in solution form white flakes.

At pH>8 emulsion were separated into oil and water phases in a period of not less than 40 days.

At pH 5 and 8, the extraction time of 2 hours, at a pH of 1 to 3 and pH 6 - 7 extraction time of 48 hours


SmCl3CRef= 114, pH 7, K = 1,2 108>

Sm(NO3)3CRef= 841, pH 8, K = 1,6 105>

Sm2(SO4)3CRef= 941 - 1008, pH 7, K = (1.5 to 3.0) 103.

2. The nature of the anion and initial solution concentrations affect the results of the extraction.

3. The extraction time is minimal from sulfate solutions and most of chloride.

Example 5 (table, experience 5). The extraction was carried out from aqueous solution TbCl3when the concentration of the initial solution CRef= 444 mg/DM3and when pHRef= 5,1 in the range of 1<pH<8.4correspond to the values of pH 2 and pH 6 - 7.

The minimum concentration of terbium in the raffinate 1.7 mg/DM3obtained at pH 6 - 8.

At pH 8 the resulting crystalline precipitate.

At pH 5 to 7, the extraction time of 2 hours, at a pH of 1 to 3 and pH 8, the extraction time is 48 hours

Example 6 (table 6). The extraction was carried out from aqueous solution ErCl3when the concentration of the initial solution CRef= 396 mg/DM3and pHRef= 4,3 in the interval 0<pH<10.8according to the Chen at pH 7 - 10. This value is determined by the accuracy of ongoing weight analysis.

At pH 8 to 10 the resulting crystalline precipitate.

At pH 4 to 7, the extraction time of 2 h, at pH 1 to 2 and 8, the extraction time is 48 hours

Example 7 (table, experience 7). The extraction was carried out from aqueous solution YbCl3when the concentration of the initial solution CRef= 446 mg/DM3and pHRef= 5,1 in the range of 1<pH<8.3correspond to the values of pH 3 and pH 6.

The minimum concentration of ytterbium in the raffinate 1 mg/DM3obtained at pH 8.

At pH 7 - 8 forms a powdery residue.

At pH 4 to 6 and pH 1 extraction time of 24 h, at pH 2 to 3 and pH 7 to 8 time of extraction 48 hours

From the table we can draw the following conclusions:

1. Extraction of REE is in the range of 0<pH<10, while for most of the REE at pH 1 - 4 distribution coefficient varies in the range K = 50-500, at pH 5 - 10 the distribution coefficient varies within K = 103- 108. High distribution coefficients of metals in a certain range of pH indicate the possibility for deep extraction of REE in the performance of this extractant.

2. The coefficient of recepcii, temperature and other process parameters.

3. Significant differences in the values of the distribution coefficient of the REE under the same conditions of the extraction point to a possible practically significant differences in the partition coefficients of REE and the possibility of selective extraction when their joint presence in solution.

4. Research has shown the possibility of selective extraction of REE from aqueous solutions in the presence of ions of non-ferrous metals, iron and several anions.

5. Technical lubrication SP-3, is used as the extractant, in comparison with commonly used extractants, easily accessible and inexpensive.

Engine oil contained in the lubricant composition SP-3 and used in extraction as an inert diluent, less volatile and therefore less pozharoopasna compared to commonly used.

Use for the purpose of extraction of the treated water-oil emulsion-based lubricant SP-3 significantly reduces the cost of the process.

The proposed extraction method of REE extraction can be applied to the technological solutions, waste water in industry, mine and mine UXO increases the recovery of REE while efficiency and process safety.

Extraction of rare earth elements from aqueous solutions, including contact of the extractant and the solution, stirring the mixture, settling and separation of the phases, characterized in that the extractant use technical lubricant, in its composition with an inert diluent, in the following ratio, wt.%:

Oleic acid to 10 - 12

Triethanolamine - 4,5 - 6,0

Engine oil (inert diluent) - Rest

and extraction is carried out in the interval 0 < pH < 10 a continuous regulation of the optimal pH for a period of not more than 2 hours

 

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EFFECT: improved separating method.

5 tbl, 5 ex

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