RU2462523C1 - Method of extraction of rare-earth elements from technological and productive solutions - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method for extracting rare-earth elements from the technological and productive solutions containing iron (III) and aluminium, with a pH-0.5÷2.5, includes the sorption of rare-earth elements with strong-acid cation resin. As the strong-acid cation resin the microporous strong-acid cation resin is used based on hypercrosslinked polystyrene having a size of micropores 1-2 nm.

EFFECT: higher efficiency of the process due to greater sorption capacity of the said strong-acid cation resin, high kinetics of sorption and selectivity, improvement of the subsequent quality of eluates and simplification of the process of their further processing.

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Description

The invention relates to hydrometallurgy of rare metals, in particular to the field of extraction of rare earth elements (REE) in the complex processing of technological and productive solutions, and can be used in the technology of obtaining REE concentrates.

In connection with the restoration of the rare-earth industry in Russia, the task of the associated extraction of rare-earth elements (REE) in the ferrous, non-ferrous and rare-metal industries, as well as involving non-traditional raw materials in processing, is becoming urgent. The features of these sources are, as a rule, low REE contents and complex chemical composition. In this regard, many technologies developed by industry for concentration and extraction of REEs are unsuitable and inefficient. In addition, the choice of REE extraction method is often associated with the impossibility of changing the chemical composition of technological intermediates in closed technologies.

The sorption extraction of REE seems to be most appropriate at the stage of primary concentration. A serious problem in the sorption extraction of REE from technological and productive solutions with pH 0.5 ÷ 2.5 is the presence in them of a large amount of iron (III) and Al, because it is known that such a medium is non-selective for the separation of iron (III) and Al (as the most interfering impurities) from REE, both at the sorption stage and at the desorption stage [K. Bolshakov Chemistry and technology of rare and trace elements. Part 2 - M .: Higher school. 1976. - 360 p.]. In practice, the task of extracting REE from such solutions is solved by hydrolytic precipitation of iron (III) and Al with alkaline agents [Mursalimova ML, Stroeva E.V. Determination of the equilibrium sorption parameters of yttrium and lanthanum ions from mineralized solutions and iron-containing pulps on gel type KB-4 carboxyl cation exchanger. // Bulletin of OSU, No. 5, 2006, p. 86-90]. The disadvantages of this method include the large losses of REE (20 ÷ 25%) due to coprecipitation with hydroxides of iron (III) and Al, the use of strong solutions of precipitators, their high consumption, the formation of difficult to process waste water.

Another method is a preliminary reduction in a solution with pH 0.5 ÷ 2.5 of the most interfering impurity of iron (III) to iron (II) with iron chips, urea, sodium sulfite, etc. With this organization of the process, the choice of sorption systems with significant separation coefficients of iron (II) and REE is much wider [A.S. 2070595. A method of extracting cerium / Shevchuk Ivan Alekseevich, Simonova Tamara Nikolaevna, Rokun Antonina Nikolaevna // Publ. 12/20/1996]. The disadvantage of this method is a change in the chemical composition of technological solutions with a high consumption of reagent reductants.

At the same time, in a number of industries, maintaining a high concentration of dissolved iron (III) is dictated by technological necessity, because its presence helps to increase the leaching (oxidizing) ability of solutions [E.A. Tolstov. Physicochemical geotechnologies for the development of uranium and gold deposits in the Kyzylkum region. - M.: MGGU. 1999. - 331 p.]. Therefore, the development of a method for the selective extraction of REE from solutions with a pH of 0.5 ÷ 2.5 containing iron (III) and Al without changing the chemical composition of the solutions is an extremely urgent task.

The known method [Smirnov D.I., Molchanova T.V., Divers L.I., Peganov V.A. Sorption extraction of rare earth elements, yttrium and aluminum from red mud. // Non-ferrous metals. - 2002. - No. 8. - S.64-69], in which the extraction of REE from the technological solution pH 0.5 ÷ 2.5 is carried out by sorption on gel sulfocationic acid KU-2. Obtained after precipitation, the rough concentrate contains,%: REE - 1; iron - 2.0-2.2; aluminum - 15-18; water - 82. Next, a reprecipitation stage is proposed with the aim of bringing the rough concentrate of rare-earth metals to marketable products of 30-40%.

The main disadvantages of this method are the small sorption capacity of cation exchanger in the amount of REE, and therefore, the complex subsequent operation of bringing the rough concentrate of REE to marketable products. These shortcomings lead to the need to use additional equipment - reactors for dissolving hydrates, filters for filtering a large number of intermediate products, as well as to the additional consumption of a rather expensive reagent - alkali during aluminum leaching. In addition, the degree of REE extraction by this method is quite low - the yield is 60%.

The closest in technical essence and the achieved result is a method (prototype) for the extraction of REE in the presence of iron (III) and Al from solutions with pH 0.5 ÷ 2.5, in which for the extraction of REE are used sulfocationic macroporous structure with a divinylbenzene content from 8 to 12% [E .I. Kazantsev, A.N. Denisov. GC. 1963, 8, No. 9, 2189]. Such sulfocationionites are obtained by copolymerization of monomers (styrene and divinylbenzene) in the presence of inert additives, which are then removed from the polymer structure. However, the relatively low values of their sorption capacity due to the fact that the copolymerization process with divinylbenzene far from always ensures uniform distribution of cross-links in the polymer network are a significant drawback of sulfocationic macroporous structures. This leads to the formation of cavities in the volume of macroporous sulfocathionites, inaccessible to sorbed ions, and hence to a decrease in sorption capacity.

In addition, macroporous, and to a large extent, gel-like sulfonation cations that are swollen in water change in volume upon contact with concentrated electrolyte solutions. Changing the volume of the sulfocationite layer reduces the efficiency of the separation process and shortens the life of the sulfocationite.

The most satisfactory requirements are microporous sulfocationionites based on hypercrosslinked polystyrene. The process of forming an ultra-cross-linked polystyrene network is fundamentally different from the synthesis of traditional styrene-divinylbenzene copolymers. Supercrosslinked polystyrene is obtained not by copolymerization of styrene and divinylbenzene, but by crosslinking of dissolved or highly swollen polystyrene chains with a large number of rigid spacer bridges. This leads to the fact that in all hypercrosslinked polystyrenes, small cavities characteristic of gel nonporous styrene copolymers with a radius of 0.1–0.5 nm practically disappear, and larger cavities appear with a size distribution of 1–2 nm - micropores. The result is a porous structure with a very large internal surface of more than 1000 m ² / g. The size of the macropores in macroporous sulfocationionites varies from 50 to 1000 nm, depending on the content of divinylbenzene.

The size of micropores is commensurate with the size of hydrated ions of simple mineral electrolytes, which introduces the main effect in the separation process, reducing the ability of more hydrated (and therefore having a larger size) iron (III) and Al ions in solutions with pH 0.5 ÷ 2.5, due to sieve effect, penetrate into the volume of microporous sulfocationite to its functional groups.

A characteristic feature of microporous sulfocathionite based on hypercrosslinked polystyrene is that it does not change in volume when replacing water with concentrated electrolyte solutions due to the fact that the three-dimensional network of hypercrosslinked polystyrene has an extremely rigid frame.

The objective of the present invention is to provide a more efficient, sorption method for the extraction of REE from solutions of pH 0.5 ÷ 2.5, containing iron (III) and Al.

The problem is achieved according to the method, which consists in the sorption extraction of the amount of REE microporous sulfocathionite based on hypercrosslinked polystyrene.

Example 1

Sorption was carried out under static conditions from solutions of HCl, H ₂ SO ₄ , HNO ₃ (pH 0.5; 1; 1.5; 2; 2.5) containing 1000 mg / dm ³ REE (lanthanum). Samples of the studied samples of sulfocationionites (0.5 g) were contacted with stirring with 50 cm ^{3 of the} above solution for 5 days. Solutions were analyzed by inductively coupled plasma atomic emission method. Sorbability and the degree of extraction were determined by the difference between the initial and final concentration of ions in solution.

From the data of table 1 it follows that microporous sulfocationionite extracts lanthanum as effectively as gel and macroporous sulfocationionites from solutions of a selected pH range.

Example 2

Sorption was carried out under static conditions from a sulfate solution (pH 1.5) containing 1000 mg / dm ³ REE (lanthanum). Samples of the studied samples of sulfocathionites (0.5 g) were contacted with stirring with 50 cm ^{3 of the} above solution for 0.2; one; 2; four; 8 ocloc'k. Solutions were analyzed by inductively coupled plasma atomic emission method. Sorbability and the degree of extraction were determined by the difference between the initial and final concentration of ions in solution.

table 2 Ionite % capacity of maximum 0.5 hours 1 hour 2 hours 4 hours 8 ocloc'k Gel sulfocationite eighteen 40 fifty 66 80 Macroporous Sulfocation 45 70 91 95 one hundred Microporous sulfocationite 71 93 96 98 one hundred

From the data of Table 2 it follows that the kinetics of lanthanum extraction by microporous sulfocationionite is much higher than the kinetics of sorption of lanthanum on gel and macroporous sulfocationionites from solutions of a selected pH range.

Example 3

Sorption was carried out under static conditions from a sulfate solution (pH 1.5) containing 1000 mg / dm ³ REE (lanthanum). Samples of the studied samples of sulfocathionites (0.5 g) were contacted with stirring with 50 cm ^{3 of the} above solution at a temperature of 20; 40; 60; 80 ° C for 3 hours. Solutions were analyzed by inductively coupled plasma atomic emission method. Sorbability and the degree of extraction were determined by the difference between the initial and final concentration of ions in solution.

Table 3 Ionite The degree of extraction,% 20 ° C 40 ° C 60 ° C 80 ° C Gel sulfocationite 55 57 60 63 Macroporous Sulfocation 92 93 94 95 Microporous sulfocationite 97 98 one hundred one hundred

From the data of table 3 it follows that the temperature of the sorption extraction of lanthanum by sulfocathionites does not significantly affect the degree of extraction from acidic solutions.

Example 4

Sorption was carried out under static conditions from a sulfate solution (pH 0.5; 1; 1.5; 2; 2.5) containing 50 mg / dm ^{3 of} lanthanum, 1000 mg / dm ^{3 of} iron (III) and 1000 mg / dm ^{3 of} aluminum. Samples of the studied samples of sulfocathionites (0.5 g) were contacted with stirring with 50 cm ^{3 of the} above solution at a temperature of 20 ° C for 5 days. Solutions were analyzed by inductively coupled plasma atomic emission method. Sorbability and the degree of extraction were determined by the difference between the initial and final concentration of ions in solution.

From the data of table 4 it follows that microporous sulfocationionite has a significantly larger capacity for REE (lanthanum) in the presence of a 20-fold excess of iron (III) and Al and a lower capacity for these elements in comparison with gel and macroporous sulfocationionites when sorbed from solutions of a selected pH range .

Example 5

Sorption was carried out under static conditions from sulfate solutions (pH 1.5) containing 50 mg / dm ^{3 of} lanthanum, or containing 50 mg / dm ^{3 of} cerium, or containing 50 mg / dm ^{3 of} dysprosium, or containing 50 mg / dm ^{3 of} lutetium, or containing 50 mg / dm ^{3 the} amount of REE. Samples of the studied samples of sulfocathionites (0.5 g) were contacted with stirring with 50 cm ^{3 of the} above solution at a temperature of 20 ° C for 5 days. Solutions were analyzed by inductively coupled plasma atomic emission method. Sorbability and the degree of extraction were determined by the difference between the initial and final concentration of ions in solution.

Table 5 Ionite The degree of extraction,% La Xie Dy Lu Σ REE Microporous cation exchanger 55 57 55 57 56

Thus, the technical result of the proposed method for the extraction of REE from solutions with pH 0.5 ÷ 2.5 is determined by the high efficiency of this method due to the greater sorption capacity of microporous sulfocathionite by REE in the presence of iron (III) and aluminum, high sorption kinetics and selectivity, which leads to an improvement in the subsequent quality of eluates and simplification of the process of their further processing.

Claims (1)

The method of extracting rare earth elements from technological and productive solutions containing iron (III) and aluminum, with a pH of 0.5 ÷ 2.5, including the sorption of rare earth elements by sulfocathionite, characterized in that microporous sulfocationionite based on hypercrosslinked polystyrene having micropore size 1-2 nm.