RU2767924C1 - Method for selective extraction of scandium from rare earth concentrates - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy of rare metals and can be used in the technology of selective extraction of scandium from concentrates of rare earth elements (REE). To isolate scandium from an aqueous solution containing scandium nitrate, yttrium nitrate, rare earth nitrates and nitric acid, extraction is carried out. A 0.01 mol/l solution of N6,N6'-diethyl-N6,N6'-bis(2-fluorophenyl)-[2,2'-bipyridyl]-6,6'-dicarboxamide in nitrobenzene is used as an extractant. The extraction is carried out at a concentration of nitric acid of 3-4.5 mol/l for 3 minutes.

EFFECT: invention increases the separation coefficients of metals and the possibility of carrying out the process of selective extraction of scandium from nitric acid solutions of rare-earth nitrates immediately before carrying out the processes of their group separation according to the standard technological scheme.

1 cl, 1 tbl, 2 ex

Description

The invention relates to the field of metallurgy of rare metals and can be used in the technology of selective extraction of scandium from concentrates of rare earth elements (REE).

A known method of separating scandium and REE by extraction of TIA from hydrochloric acid solutions [G.V. Kostikova, N.A. Danilov, Yu.S. Krylov, G.V. Korpusov, E.V. Salnikov. Investigation of scandium extraction with triisoamyl phosphate from various media. Message 2. Extraction of scandium from perchlorate and hydrochloric acid solutions. - Radiochemistry. 2006, vol. 48, no. 2, pp. 164-167].

The disadvantage of this method is that high scandium and REE separation coefficients are observed only at high concentrations of hydrochloric acid in the aqueous phase (more than 5 M), which creates difficulties in the separation processes, does not allow the use of stainless steel equipment, and leads to deterioration of conditions labor and environmental hazards of production, and also leads to the need to carry out operations for the conversion of REE chlorides into nitrates before carrying out the processes of their group separation processes according to the standard technological scheme.

Closest to the proposed method in terms of technical essence and the achieved result is the method of extraction separation of scandium and REE during the extraction of benzo-15-crown-5 from solutions containing lithium trichloroacetate at pH 3-5 [Kostikova G.V., Krasnova O.G. , Tsivadze A.Yu., Zhilov V.I. The method of isolating scandium from rare earth concentrates / Pat. 2626206 Ros. Federation: IPC С22В 59/00 C22B 3/26 A.N. Frumkin (IPChE RAS). - No.; dec. 2016137815 app. 09/22/2016; publ. 07/24/2017, Bull. No. 21. - 5 p.].

The disadvantage of this method is the need to introduce lithium trichloroacetate into a solution containing rare-earth and scandium nitrates, which, after the scandium extraction process, leads to the need for additional operations associated with the removal of lithium trichloroacetate from a solution of rare-earth nitrates for their further group separation.

The technical result of the invention is to increase the distribution coefficients of scandium and increase the separation coefficients of scandium and REE, as well as the absence of additional operations associated with adjusting the obtained solutions of REE nitrates before carrying out the processes of their group separation according to the standard technological scheme.

This technical result is achieved by carrying out extraction for 3 minutes from an aqueous solution containing scandium nitrate, rare earth nitrates and nitric acid. A solution of 0.01 mol/l N6,N6'-diethyl-N6,N6'-bis(2-fluorophenyl)-[2,2'-bipyridyl]-6,6'-dicarboxamide in nitrobenzene is used as an extractant and the extraction process carried out in the concentration range of nitric acid 3-4.5 mol/l.

When the concentration of nitric acid in an aqueous solution is less than 3.0 mol/l, there is a decrease in the distribution coefficients of scandium (D _Sc ) and, accordingly, the separation coefficients of scandium and REE (β _Sc/REE ) due to a decrease in the concentration of nitric acid in an aqueous solution.

When the concentration of nitric acid in an aqueous solution is more than 4.5 mol/l, the distribution coefficients of scandium (D _Sc ) and REE remain constant, thus, a further increase in the concentration of nitric acid does not lead to an increase in the separation coefficients of scandium and REE (β _Sc/REE ) .

Examples illustrating the invention.

Example 1

An aqueous solution containing a mixture of scandium, yttrium and REE nitrates (0.1 g/l in terms of metal) and 3.0 mol/l nitric acid is brought into contact with a solution of 0.01 mol/l N6,N6'- diethyl-N6,N6'-bis(2-fluorophenyl)-[2,2'-bipyridyl]-6,6'-dicarboxamide in nitrobenzene. The mixing time is 3 minutes, the ratio of the volumes of the phases o:b=1:1. In this case, the scandium distribution coefficient (D _Sc ) is 43, the distribution coefficients of yttrium and REE are 0.001÷0.006, and the separation coefficients β _Sc/Ln are 7153÷43000 (table 1).

Example 2

An aqueous solution containing a mixture of scandium, yttrium and REE nitrates (0.1 g/l in terms of metal) and 3.7 mol/l nitric acid is brought into contact with a solution of 0.01 mol/l N6,N6'- diethyl-N6,N6'-bis(2-fluorophenyl)-[2,2'-bipyridyl]-6,6'-dicarboxamide in nitrobenzene. The mixing time is 3 minutes, the ratio of the volumes of the phases o:b=1:1. In this case, the scandium distribution coefficient (D _Sc ) is 260, the distribution coefficients of yttrium and REE are 0.016÷0.044, and the separation coefficients β _Sc/Ln are 7477÷16568 (table 1).

Example 3.

An aqueous solution containing a mixture of scandium, yttrium and REE nitrates (0.1 g/l in terms of metal) and 4.5 mol/l nitric acid is brought into contact with a solution of 0.01 mol/l N6,N6'- diethyl-N6,N6'-bis(2-fluorophenyl)-[2,2'-bipyridyl]-6,6'-dicarboxamide in nitrobenzene. The mixing time is 3 minutes, the ratio of the volumes of the phases o:b=1:1. In this case, the scandium partition coefficient (D _Sc ) is 475, the distribution coefficients of yttrium and REE are 0.028÷0.088, and the separation coefficients β _Sc/Ln are 5396÷16878 (table 1).

Table 1. Values of distribution coefficients (D) and separation coefficients (β) of Sc and REE during extraction with a solution of 0.01 mol/l N6,N6'-diethyl-N6,N6'-bis(2-fluorophenyl)-[2,2' -bipyridyl]-6,6'-dicarboxamide in nitrobenzene from nitric acid solutions

Element Example 1 Example 2 Example 3 _3.0M HNO3 _3.7M HNO3 _4.5M HNO3 D β _Sc/Ln D β _Sc/Ln D β _Sc/Ln sc 43 260 475 Y 0.003 13258 0.016 16568 0.028 16878 La 0.001 43000 0.016 16265 0.031 15338 Ce 0.001 43000 0.020 13081 0.039 12257 Pr 0.004 11893 0.026 9828 0.049 9636 Nd 0.003 14333 0.034 7739 0.072 6604 sm 0.004 10750 0.031 8310 0.088 5396 Eu 0.001 43000 0.044 5968 0.086 5514 Gd 0.006 7153 0.033 7767 0.061 7795 Tb 0.004 9907 0.039 6693 0.073 6475 Dy 0.001 28738 0.033 7841 0.065 7328 Ho 0.005 8069 0.035 7477 0.064 7397 Er 0.001 43000 0.033 7843 0.065 7274 Tm 0.001 43000 0.027 9536 0.054 8873 Yb 0.001 43000 0.020 13292 0.038 12460 Lu 0.001 43000 0.025 10544 0.048 9831

As can be seen in all the examples given, upon extraction with a solution of 0.01 mol/l N6,N6'-diethyl-N6,N6'-bis(2-fluorophenyl)-[2,2'-bipyridyl]-6,6'-dicarboxamide in nitrobenzene from nitric acid solutions, the separation coefficients of scandium and REE are significantly higher (in all cases more than 5000) than in the extraction of benzo-15-crown-5 from neutral trichloroacetate solutions, which allows using various extraction methods at a large ratio of phase flows (B:O> 20:1) to carry out selective extraction of scandium from nitric acid solutions of rare-earth nitrates immediately before carrying out the processes of their group separation according to the standard technological scheme. This will both increase the efficiency and productivity of the process, and reduce the number of technological operations.

Claims (1)

A method for separating scandium from an aqueous solution containing scandium nitrate, yttrium nitrate, nitrates of rare earth elements and nitric acid, including extraction, characterized in that a 0.01 mol/l solution of N6,N6'-diethyl-N6,N6 is used as an extractant '-bis(2-fluorophenyl)-[2,2'-bipyridyl]-6,6'-dicarboxamide in nitrobenzene, while the extraction is carried out at a concentration of nitric acid of 3-4.5 mol/l for 3 minutes.