ES2325292B1 - PROCEDURE FOR THE RECOVERY OF GERMANIUM IN DISSOLUTION BY COMPLEXING AND USING ION EXCHANGE RESINS. - Google Patents

Abstract

Germanium recovery procedure in solution by complexing and using resins of ion exchange

The present invention describes a process for the recovery of germanium in aqueous solution, by anion exchange resins based on the formation of a anionic complex of germanium with an agent, complexing and the subsequent extraction of said complex by an anionic resin. The selection of the most appropriate operating conditions in the process extraction, such as the amount of complexing agent, the pH or the resin mass, among others, allows to reach a selective and high retention of germanium. The procedure also contemplates the discharge of resin germanium, by destroying the union between the germanium complex and the resin. In the same way than in the previous stage, the appropriate selection of the variables that affect the download stage, makes it possible to obtain high percentages of germanium recovery. Also this procedure offers the possibility of concentrating germanium in the final solution quickly and easily, with an easy implementation in an industrial process of operation in continuous.

Description

Germanium recovery procedure in solution by complexing and using resins of ion exchange

Object of the invention

The invention relates to a method for the recovery of germanium present in aqueous solutions, which separates from other metals also present in said solution by using ion exchange resins. The selective extraction is achieved by forming a organic germanium complex, which is adsorbed in a resin conventional anionic Finally, germanium is desorbed from the resin by contacting it with an aqueous solution, which can be acidic, basic or neutral. The possibility of selecting a desorption solution facilitates the possible subsequent operations to obtain the highest purity germanium. After desorption, the resin can be regenerated for a new utilization.

In addition to the separation of impurities, this procedure achieves a degree of concentration in the final solution of germanium about 20 times, with respect to the original solution.

State of the art

The estimated concentration of germanium (Ge) in the earth's crust is in the range 1-7 ppm, but its extraction is not simple, since it is quite dispersed and is only concentrated in some minerals such as germanite or renierite . Although almost all primary germanium is currently recovered as a byproduct of Zn refining, Germanium-rich coals have regained importance due to the depletion of some germanium ores ( Van Lier, RJM; Dreisinger, DB (1995) Sep. Processes Proc Symp. 203-24 ). The Ge is generally recovered from the ashes, which may contain a concentration of Ge about ten times greater than that of the original coal, after a first stage of leaching it, obtaining an aqueous solution containing Ge in low concentrations with other metals , such as Zn, Cu or Fe. Therefore, the separation and concentration of Ge from aqueous extracts of coal ashes is a great technological challenge.

The methods described in the bibliography for the separation or recovery of the Ge present in aqueous solutions, among which the following:

one.

Precipitation, as can be seen in the works of Jandová ( Jandová, J .; Stefanova, T .; Vu, H. (2001). Proceedings of EMC 2001, 69-75), Font (Font, O. (2007). Doctoral Thesis Department of Mining Engineering and Natural Resources of the Polytechnic University of Catalonia (UPC) or Schoeller (Schoeller. Analyst. 1932, 57: 551 ).

2.

Extraction with Cl 4 C from strongly acidic solutions in hydrochloric medium ( Schoeller. Analyst. 1932, 57: 551 ).

3.

Distillation of GeCl_ {4} ( Jandova, J .; Vu, H .; Fecko, P. (2002). Proceedings-Annual International Pittsburgh Coal Conference 19, 1075-1080 ).

Four.

Ionic flotation ( Hernández-Expósito, A .; Chimenos, JM; Fernández, AI; Font, O .; Querol, X .; Coca, P .; García-Peña, F. (2006). Chem. Eng. J. 118 , 69-75; Matis, KA; Mavros, P. (1991). Sep. & Purif. Reviews 20 (1), pp 1-48; Matis, KA; Stalidis, GA; Zoumboulis, AI (1988). Sep. Sci. Technol. 23 (4-5), pp. 347-362 ).

5.

Adsorption on activated carbon ( Marco, J .; Cazorla, D .; Linares, A. (2006). Patent ES2257181 ).

6.

Extraction with solvents, usually after complexing with various organic reagents, including hydroxyoxime and 8-hydroxyquinoline derivatives, which have been used industrially, using commercial products such as LIX 63 (an oxime from Henkel Corporation), LIX 26 (an 8-hydroxyquinoline from Henkel Corporation) and Kelex 100 (an 8-hydroxyquinoline from (Sherex Chemical Company) ( Deschepper, A .; Van Peteghem. A., US 3883634; Rouillard, D .; Cote, G .; Fossi , P .; Marchon, B., US 4389379; De Schepper A .; Coussement, M .; Van Peteghem, A., US 4432951) Menéndez et al . Detail in their patent (Menendez, FJS; Menendez, FMS; De La Cuadra Herrera, A .; Tamargo, FA; Lorenzo, LP; Valcarcel, MR; Fernandez, VA, US 4886648 ) a process of recovery of germanium, in particular of diluted solutions, by the addition of tartaric acid and extraction with a organic phase that contains a tertiary amine.

7.

Use of ion exchange resins. More recently, and due to the waste generated in most of the previous processes, Ge recovery studies have been carried out from aqueous solutions by means of resin extraction. Strongly basic conventional resins can separate germanium (IV), but not selectively ( Everest, DA; Salmon, JE (1954) J. Chem. Soc. 2438; Everest, DA Popiel, WJ (1956) J. Chem. Soc. 3183; Everest, DA Popiel, WJ (1957) J. Chem. Soc. 2433; Everest DA; Popiel. WJ (1958) J. Inorg. Nucl. Chem. 6 p. 153). Despite this, the work of (Boateng, DA D; Ball; DL; Swinkels; GM (19), US 4525332 ) ensures that both weakly basic and strongly basic resins are suitable for extracting Ge in the presence of antimony and zinc

In the works of Inukai et al . ( Inukai Y .; Chinen T .; Matsuda T .; Kaida Y .; Yasuda S. (1998). Analytica Chimica Acta 371 (2) 187-193 (7 )) and Harada et al . ( Harada, A. Tarutani T .; Yoshimura. K. (1988) Anal. Chim. Acta 209, p. 333 ), it is stated that Ge (IV) is not retained on conventional chelating resins for metal cations, since in aqueous solution, Ge is not in cationic form, but in the form of oxoacid (Ge (OH) 4), or oxoanions (GeO (OH) 3- and GeO2 (OH) 2 -2) depending on the pH of the solution. The same authors assure that a strongly basic anionic resin would extract the germanium in solution, but not selectively ( DA Everest, WJ Popiel. (1956) J. Chem. Soc. 3183, DA Everest, WJ Popie. (1957) J. Chem. Soc. 2433, DA Everest and WJ Popiel. (1958) J. Inorg. Nuc. Chem. 6, p. 153 ).

Because germanium complexes with diphenolic compounds and polysaccharides ( Antikainen. PJ (1959) Acta Chem. Scand. 13, p. 312; Antikainen PJ; Huttunen E. (1973). Suomen Kemistilehti B 46, p. 184 ), There are some studies that have studied the selective extraction of Ge using resins that contain the appropriate functional groups on their surface. There are two ways to obtain an ion exchange resin with functional groups: 1. Incorporate the functional group during polymerization, for example using already functionalized monomers, or 2. Introduce the functional groups on the matrix after polymerization, by means of the appropriate chemical reactions . Thus, there are specific commercial resins for the extraction of Ge, such as Sephadex ( Harada, A .; Tarutani T .; Yoshimura. K. (1988). Anal. Chim. Acta 209, p. 333 ) and N-methylglucamine ( Yasuda S .; Kawazu K. (1988). Bunseki Kagaku 37, p. T67; Schilde, U .; Uhlemann E. (1993). React. Polym. 20, p. 181; Schilde, U .; Kraudeit H .; Uhlemann , E. (1994). React. Polym. 22, p. 101; Yoshimura, K .; Kariya, R .; Tarutani, T. (1979) Anal. Chim. Acta 109, p. 115; Yasuda, S .; Yamauchi, H .; (1987) Nippon Kagaku Kaishi 752; Schilde, U .; Uhlemann, E. (1992). React. Polym. 18, p. 155 ), which present some problems of selectivity, or resins such as those manufactured by Inukai et al . (Inukai Y .; Chinen T .; Matsuda T .; Kaida Y .; Yasuda S. (1998). Anal. Chim. Acta, vol. 371, 2 (5), 187-193 (7)), which synthesize resins polystyrene chelators with groups 1, 2 diol or 1, 3 diol, or chitosan type, with very good yields both loading and unloading. This same type of resins is described in the work of Hayashi et al . ( Hayashi, H .; Ueno, H .; Kogyo, G (1985). US Patent 4525332 ). Kunio et al . ( Kunio, S .; Akira, T .; Hiroyuk, Ti; Masahide, H; Shiyouzou, T; Kouzou, K (1985) Method of recovery of germanium Patent JP 60166225 ) have patented a process in which Ge recovers in a way selective from diluted solutions, using a resin that is loaded with a complexing substance of Ge, such as tannin. Another similar work is that of Ziegenbalg ( Ziegenbalg, S .; Scheffer, E. (1963). GB 933563 ) in which various complexing agents containing hydroxyl groups are introduced into the resin. Elution of Ge is performed in all cases with a concentrated HCI solution (molarity above 7 M). The main problem of most of these chelating resins is their high price, a slower absorption kinetics.

Description of the figures

Figure 1.- Catechol structure (CAT).

Figure 2.- structure of the complex Germanium-Catechol.

Description of the invention

The present invention relates to a procedure for the recovery of germanium from aqueous solutions and provides a simple and effective process to the concentration and selective separation of germanium from aqueous solutions containing other metals, such as zinc, antimony, arsenic, cobalt, vanadium, molybdenum or nickel. He The process of the invention comprises the following steps:

Stage I

Formation of the Ge complex by adding to the aqueous solution of some reagent that forms complexes anionic with this element, such as catechol, some acids dicarboxylic and other diphenols. The catechol has been selected due to its selectivity towards the Ge, and its low cost if Compare with other complexing agents. This stage can be done. using different CAT / Ge molar ratios, although the Minimum quantity should be the stoichiometric ratio, which is 3. Once the catechol is dissolved in the solution, the formation of the complex is practically instantaneous, in conditions of agitation that allow a good contact between the Ge and the catechol. How has it said, the stability of the Ge-catechol complex and the values of the successive acid constants of the catechol determine a range of maximum stability of the complex between pH = 4-9, although for other complexing agents this interval may vary.

Stage II

Extraction with ion exchange resins, what which is done by contacting the fertile solution (F) that contains the Ge-CAT complex with a certain amount of resin. This contact can be made discontinuously, adding the resin to the solution and stirring, or continuously by employing columns

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The choice of resin is carried out between anionic resins, strongly basic and macroporous, which they have pore sizes large enough to retain in them the germanium complex. The amount of resin that is It is necessary to add, expressed in the form of equivalents, to be at minus 2 times the number of equivalents of Ge, although a greater excess can shift the balance favorably to the extraction.

The contact time can be adjusted from about minutes to longer times, depending on the type of contact and the extraction performance required. In the examples included in the present patent, the contact has been maintained for 7 h although it has been proven that shorter contact times also allow the extraction of the complex. The contact can be continuous, using resin filled columns; or discontinuous, using vessels with stirring. After extraction, the aqueous solution resulting or refined (R) is practically free of germanium, while the rest of the metals remain in the refined, and the resin is loaded with the Ge-CAT complex.

Stage III

Separation of resin and refining by filtration or by other methods.

Stage IV

Unloading of the Ge contained in the resin, for that the resin loaded with Ge is contacted with a solution aqueous eluent (E) containing the agent responsible for break the union between the complex and the functional groups of the resin. One of the advantages of the resin extraction method proposed lies in the possibility of choosing the download process in acidic, basic, or neutral medium. Although the germanium discharge it is possible using NaOH, NaCl and HCl solutions, with molarities greater than 0.5 M, the best yields have been obtained with molarity solutions greater than 1 M in all three cases.

In the elution stage the germanium, using a volume of solution E less than that of the Original F solution, allowing reagent savings. I dont know recommends that the ratio between F / E volumes be greater than 20, due to a decrease in download performance.

As in stage II, this contact can be carried out discontinuously or continuously. Contact time It can also be adjusted from a few minutes to longer times. In the examples included in this patent, it has been maintained the contact for 7 h although it has been verified that shorter times of contact also allow the discharge of germanium.

Stage V

Solution resin separation concentrated by filtration or by other methods, to obtain an aqueous phase concentrated in Ge and practically free of others elements, which will be called concentrated solution (C).

Stage SAW

Optionally, the concentrated solution (C) can be reused again as an eluent solution in a new process of discharge of Ge, producing an increase in concentration Ge end with each reuse.

Stage VII

Regeneration of the resin by one or several cycles with different aqueous solutions before a new one use, to reinstate the active groups, and condition it for its new use in the process. You can use HCl or NaCl, if the resin is to be used in chloride form, or NaOH, if the resin is desired to have hydroxide form. The concentration of these solutions must be much higher than eluent solutions (according to the specifications of the manufacturer), and an excess of more than 100% of the theoretical capacity of the resin.

Embodiment of the invention

To illustrate the procedure described in the The present invention describes the following examples, but in No case should be considered as limiting it.

Example 1 Extraction of Ge with a resin of type IRA-958 (Rohm-Haas)

It starts from 75 mL of a standard with 100 mg / L of Ge. To this solution is added 35 mg of catechol (CAT), and shake well. The original pH of the solution (2,1) is increased to 7.8 by adding 6 mL of a 0.1 M solution of NaOH.

The above solution contacts 340 mg of an IRA-958 resin (in chloride form), and maintains contact between the phases for 7 h, at temperature ambient.

Next, the phases are separated: the resin, that is loaded with the Ge complex, and the solution is practically free of that element (refined). The refining is analyzed, and its Ge content turns out to be less than 5 mg / L, so the Extraction yield is greater than 95%.

Example 2 Extraction of Ge with a resin of the IRA-900 type (Rohm-Haas) from a solution obtained by leaching an ash from a plant thermal

It starts from 1000 mL of a liquid solution (solution L) whose composition is shown in Table 1. The solution L has been obtained by extracting a fly ash with water from a thermal power plant at room temperature for 24 h, in a reactor with stirring at atmospheric pressure.

To the solution L is added 296 mg of catechol (CAT), and stir well. The original pH of the solution (4.2) is increases to 7.1 by adding 15 mL of a 0.1 solution M of NaOH.

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TABLE 1 Composition of solution L

one

The above solution contacts 1524 mg of an IRA-900 resin (in chloride form), and contact is maintained by flipping for 7 h at temperature ambient.

Subsequently the phases are separated, and the Refined is saved for analysis. Its composition is shown in the Table 2. Said composition shows how the extracted germanium assumes 92.6% of the initially present in solution L, while the rest of the elements remain in the liquid solution, that is, they are barely extracted by the resin, resulting in the operation selective for the Ge. As you can see, they are just something retained by the resin: Sb, V, Mo and Ni, much less As or Zn, but in all cases to a much lesser extent than germanium. There is It should also be noted that the initial quantities of elements such as V, Mo or Zn (<2.5 mg / L) in ash leachate (solution L) they are much smaller than those of Ge (35.6 mg / L).

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TABLE 2 Refined composition (R)

2

Example 3 Discharge of the adsorbed Ge on a resin IRA-958 caused by a NaCl solution

It starts from 1889 mg of a resin loaded with Ge for having been contacted with the previous L solution. How It has been indicated above, in this resin they have been retained, In addition to germanium, small amounts of other elements. The maximum amount of each of these elements that can be found in the resin has been calculated by difference between the concentration of each element in the liquid solution (L) and the refined (R), and said amounts are shown in Table 3.

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TABLE 3 Maximum amounts absorbed in the resin

3

Next, the germanium charged resin is contacts 150 mL of a 3M sodium chloride solution and both phases are kept agitated by flipping for 7 h at room temperature. The phases are separated, and the chloride solution sodium now has the composition indicated in Table 4. In this case, reextracted germanium accounts for 89.2% of the content in the resin.

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TABLE 4 Composition of the concentrated solution (solution C) obtained after discharge of germanium and yields of discharge

4

When comparing metal concentrations in the original solution L (Table 1) with those observed in the table above (concentrated solution), the goodness of a method that allows you to concentrate the Ge about four times, at the same time that reduces the presence of the main interference

Example 4 Extraction of Ge with an IRA-958 resin and discharge produced by a NaCl solution

It starts from 1000 mL of a liquid solution (solution L). To this solution is added 294 mg of catechol (CAT), and stir well. The original pH of the solution (4.3) is increases to 7 by adding 15 mL of a 0.1 M solution NaOH The above solution is contacted with 1893 mg of an IRA-958 resin (in chloride form), and it maintains contact by flipping for 7 h at temperature ambient.

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TABLE 5 Extraction yields by element

5

The phases are separated, and the refining is saved For analysis. Extraction yields are shown in the Table 5. In this example, the extracted germanium accounts for 93.1% of the initially present in solution L, while the rest of Elements barely changes its concentration. Just adsorb partially in the resin: Sb, Co, V, Mo, Ni or Zn, but in all cases to a much lesser extent than germanium, and in almost all cases, starting from much lower concentrations (<2.5 mg / L) than that of Ge in the original solution.

Next, the germanium charged resin is contacts 250 mL of a 3M sodium chloride solution and both phases are kept agitated by flipping for 7 h at room temperature. Then the phases are separated, and the solution of sodium chloride is analyzed. Download performances are shown in Table 6. This table also shows the concentrations of these elements present in the concentrated solution (C).

Again, the considerations made in example 3 concerning the selectivity of the method and the concentration of Ge.

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TABLE 6 Composition of the concentrated solution (solution C) obtained after discharge of germanium and elution yields by elements

6

Table 7 shows the yields Global upload and download (%) of each item in the operation explained in example 4.

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TABLE 7 Global returns of loading and unloading of the Ge and main elements interfering

7

If the extraction performance is compared overall of germanium with that of the rest of the elements, you can see that the only elements whose extraction yields are high, they are the V and the Mo, probably because they are both in forms anionic in solution. However, these elements have some contained in the original liquid solution (L) less than 0.5 mg / L and in the concentrated solution (C) less than 1 mg / L. In the case of Sb, the main impurity in the extraction stage, you can see that The overall yield is 0.6%.

Claims (11)

1. A process for the recovery of the Ge present in an aqueous liquid phase (L) in which other metals are found, after the addition of a complexing agent, through the use of anion exchange resins, characterized in that it comprises: a) the complexation of the Ge contained in the liquid solution (L) by adding a reagent complexing, subsequently performing a pH adjustment to achieve maximum stability of the complex. b) the contact of the fertile solution With the exchange resin. The amount of resin, expressed in equivalent form, must be at least 2 times the number of Germanium equivalents c) separation of the resin from the solution resulting (refined, R). d) discharge of resin germanium, putting it in contact with an acidic aqueous solution (HCl), basic (NaOH) or neutral (NaCl), called eluent solution (E). e) separation of the resin from the solution concentrated in Ge (concentrated solution, C) and the regeneration of the resin by one or several cycles with acidic, basic solutions or neutral high concentration, to reinstate the groups assets, and condition it for new use in the process. 2. Method according to claim 1 characterized in that the complexation of the Ge contained in the solution L is carried out by the addition of a complexing agent selected from oxygenated organic compounds, dicarboxylic acids or poly-alcoholic compounds, or polyphenolics, capable of forming stable complexes with Germanium, such as catechol, using a catechol: Ge ratio of at least 3. 3. Method according to claim 1 characterized in that the pH selected for the formation of the complex must be in the stability range of the complex, the pH for the catechol being greater than 4 and less than 9. Method according to claim 1, characterized in that the complex extraction process is carried out by means of an anion exchange resin, strongly basic and macroporous. 5. Method according to claim 1 characterized in that the contact between the resin and the fertile solution is carried out using contact times ranging from a few minutes to several hours, the process being continuous with columns filled with resin or discontinuous with vessels of the stirred tank type . Method according to claim 1, characterized in that the separation between the resin and the refining can be carried out by filtration or by other methods, such as decantation. 7. Method according to claim 1 characterized in that the elution process is carried out with an aqueous solution of HCl, NaCl or NaOH, the concentration of which must be greater than 0.5 M. Method according to claim 1, characterized in that the discharge of the Ge is carried out by contacting the resin with different volumes of solution E, in a range of volumes of fertile solution (F) / eluent solution (E) whose value is at most 20/1, so that the final solution of Ge can be concentrated up to 20 times. 9. Method according to claim 1 characterized in that the separation between the resin and the concentrated solution can be carried out by filtration or by other methods, such as decantation. Method according to claims 1-9, characterized in that the concentrated solution (C) can be reused in several processes of discharge of Ge, producing an increase in the final concentration of Ge with each use. 11. Method according to claims 1-9 characterized in that the resins can be reused in several cycles of loading and unloading of germanium, after being subjected to regeneration for which aqueous solutions of HCl or NaCl can be used, if the resin is to be used in it forms chloride, or NaOH, if the resin is desired to have in hydroxide form, the concentration of these solutions being higher than that of the eluent solutions and in an excess greater than 100% of the theoretical capacity of the resin.