WO2009106660A1

WO2009106660A1 - Method for the recovery of germanium in solution by means of complexing and use of ion-exchange resins

Info

Publication number: WO2009106660A1
Application number: PCT/ES2009/000102
Authority: WO
Inventors: Constantino FERNÁNDEZ PEREIRA; Fátima ARROYO TORRALBO
Original assignee: Universidad De Sevilla
Priority date: 2008-02-28
Filing date: 2009-02-26
Publication date: 2009-09-03
Also published as: ES2325292B1; ES2325292A1

Abstract

The invention relates to a method for the recovery of germanium present in aqueous solutions, which is separated form other materials also present in said solutions through the use of ion-exchange resins. The selective extraction is performed by forming an organic germanium complex which is absorbed in a conventional anionic resin. Finally, the germanium is desorbed from the resin when the resin is brought into contact with an aqueous solution which can be an acid, base or neutral solution. The possibility of selecting a desorption solution facilitates the possible subsequent operations for obtaining germanium of higher purity. Following desorption, the resin can be regenerated for a new use.

Description

PROCEDURE FOR THE RECOVERY OF GERMANIUM IN

DISSOLUTION BY COMPLEXING AND USING

ION EXCHANGE RESINS

Object of the invention

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

In addition to the separation of impurities, this procedure achieves a degree of concentration in the final germanium solution of 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 being recovered as a byproduct of Zn refining, Germanium-rich coals have regained importance, due to the depletion of some germanium ores (Van Lier, RJ. M .; 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 next to 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. There are numerous methods described in the literature for the separation or recovery of the Ge present in aqueous solutions, among which the following can be mentioned:

1. 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 CI ₄ C from strongly acidic solutions in hydrochloric medium (Schoeller. Analyst. 1932, 57: 551).

3. Distillation of GeCI ₄ (Jandová, J .; Vu, H .; Fecko, P. (2002). Proceedings - Annual International Pittsburgh Coal Conference 19, 1075-1080).

4. Ionic flotation (Hernández-Expósito, A .; Chímenos, 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, among which the hydroxyoxime and derivatives of 8-hydroxyquinoline, which have been used industrially, using commercial products such as LIX 63 (an oxime of 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 an organic phase containing a tertiary amine.

7. Use of ion exchange resins. More recently, and due to the waste generated in most of the previous processes, they have been carried out Ge recovery studies 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. Nucí. Chem. 6 p. 153). Despite this, the work of (Boateng, DA D; BaII; D. L; 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, the Ge is not in cationic form, but in the form of oxoacid (Ge (OH) ₄ ), or oxoanions (GeO (OH) _3- and GeO ₂ (OH) ₂ ^"2 ) depending on the pH of Ia The same authors assure that an anionic resin, strongly basic, 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 the polymerization, for example using already functionalized monomers, or 2. Introduce the functional groups on the matrix after the 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; Masan ide, H; Shiyouzou, T; Kouzou, K (1985) Method of recoven / of Germanium Patent JP 60166225) have patented a process in which Ge recovers selectively from dilute 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 different 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 germanium-catechol complex

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

STAGE I: formation of the Ge complex by adding to the aqueous solution some reagent that forms anionic complexes with this element, such as catechol, some dicarboxylic acids and other diphenols. Catechol has been selected due to its selectivity towards Ge, and its low cost compared to other complexing agents. This stage can be performed using different CATVGe molar proportions, although the minimum amount should be the stoichiometric proportion, which is 3. Once the catechol is dissolved in the solution, the formation of the complex is practically instantaneous, under conditions of agitation that allow good contact. between the Ge and the catechol. As mentioned, the stability of the Ge-catechol complex and the values of the successive acid constants of the catechol determine a maximum stability interval of the complex between pH = 4-9, although for other complexing agents this range may vary. STAGE II: Extraction with ion exchange resins, 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 using columns.

The choice of the resin is carried out between the anionic resins, strongly basic and macroporous, which have pore sizes large enough to retain in them the germanium complex. The amount of resin that needs to be added, expressed in the form of equivalents, must be at least 2 times the number of equivalents of Ge, although a greater excess can displace the equilibrium favorably to the extraction. The contact time can be adjusted from a few minutes to longer times, depending on the type of contact and the required extraction performance. In the examples included in this patent, the contact has been maintained for 7h 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 containers with agitation. After the extraction, the resulting or refined aqueous solution (R) is practically free of germanium, while the rest of the metals remain in the refining, and the resin is loaded with the Ge-CAT complex.

STAGE III: separation of the resin and the refining by filtration or by other methods.

STEP IV: discharge of the Ge contained in the resin, for which the resin loaded with Ge is contacted with an eluent aqueous solution (E) containing the agent responsible for breaking the joint between the complex and the functional groups of The resin One of the advantages of the extraction method with The proposed resin resides in the possibility of choosing the discharge process in acidic, basic, or neutral medium. Although the discharge of germanium is possible using NaOH, NaCI and HCI 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, germanium can be concentrated, using a volume of solution E smaller than that of the original solution F, which allows a saving of reagents. It is not recommended that the ratio between F / E volumes be greater than 20, due to a decrease in discharge performance. As in stage II, this contact can be carried out discontinuously or continuously. The contact time can also be adjusted from a few minutes to longer times. In the examples included in the present patent, the contact has been maintained for 7h although it has been proven that shorter contact times also allow the discharge of germanium. STAGE V: separation of the resin from the concentrated solution by filtration or by other methods, to obtain an aqueous phase concentrated in Ge and practically free of other elements, which will be called the concentrated solution (C).

STAGE Vl: optionally, the concentrated solution (C) can be reused again as an eluent solution in a new Ge discharge process, resulting in an increase in the final concentration of Ge with each reuse.

STEP VII: regeneration of the resin by one or several cycles with different aqueous solutions before a new use, to reinstate the active groups, and condition it for its new use in the process. HCI or NaCI can be used, 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 that of the eluent solutions (according to the manufacturer's specifications), and an excess greater than 100% of the theoretical capacity of the resin must be used.

SUBSTITUTE SHEET (RULE 26) Embodiment of the invention

To illustrate the procedure described in the present invention, the following examples are described, but in no case should they be considered as limiting thereof.

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 stirred well. The original pH of the solution (2.1) is increased to 7.8 by adding 6 mL of a 0.1 M NaOH solution.

The above solution is contacted with 340 mg of an IRA-958 resin (in chloride form), and the contact between the phases is maintained for 7 h, at room temperature.

Next, the phases are separated: the resin, which is charged with the Ge complex, and the virtually free solution 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 type IRA-900 (Rohm-Haas) from a solution obtained by leaching an ash from a thermal power plant.

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

To solution L, 296 mg of catechol (CAT) _{1 is added} and stirred well. The original pH of the solution (4.2) is increased to 7.1 by adding 15 mL of a 0.1 M NaOH solution.

SUBSTITUTE SHEET (RULE 26) Table 1. Composition of solution L

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

The phases are subsequently separated, and the refining is saved for analysis. Its composition is shown in Table 2. Said composition shows how the extracted germanium represents 92.6% of the initially present in the solution L, while the rest of the elements remain in the liquid solution, that is, they are hardly extracted by Ia resin, resulting in the selective operation for the Ge. As can be seen, they are only somewhat 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. It should also be noted that the initial amounts of elements such as V, Mo or Zn (<2.5 mg / L) in ash leachate (solution L) are much smaller than those of Ge (35.6 mg / L) .

SUBSTITUTE SHEET (RULE 26) Table 2. Refining composition (R)

Example 3: discharge of the adsorbed Ge onto an IRA-958 resin caused by a NaCI solution

It starts from 1889 mg of a resin loaded with Ge for having been contacted with the previous L solution. As indicated above, in this resin, in addition to germanium, small amounts of other elements have been retained. 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 .

SUBSTITUTE SHEET (RULE 26) Table 3. Maximum amounts adsorbed on the resin

Next, the germanium-loaded resin is contacted with 150 ml of a 3M sodium chloride solution and both phases are kept stirred by flipping for 7 h at room temperature. The phases are separated, and the sodium chloride solution now presents the composition indicated in Table 4. In this case, the re-extracted germanium represents 89.2% of the resin content.

SUBSTITUTE SHEET (RULE 26) Table 4. Composition of the concentrated solution (solution C) obtained after the germanium discharge and discharge yields

When comparing the concentrations of metals in the original solution L (Table 1) with those observed in the previous table (concentrated solution), the goodness of a method that allows to concentrate the Ge about four times, while reducing The presence of the main interferences.

Example 4: Ge extraction with an IRA-958 resin and discharge produced by a NaCI solution

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

The phases are separated, and the refining is saved for analysis. The extraction yields are shown in Table 5. In this example, the extracted germanium represents 93.1% of that initially present in solution L, while the rest of the elements hardly change their concentration. Only partially adsorbed 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.

SUBSTITUTE SHEET (RULE 26) Table 5. Extraction performances by element

Next, the germanium-loaded resin is contacted with 250 ml of a 3M sodium chloride solution and both phases are kept stirred by flipping for 7 h at room temperature. Then the phases are separated, and the sodium chloride solution is analyzed. The discharge yields 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 regarding the selectivity of the method and the concentration of the Ge can be made here.

SUBSTITUTE SHEET (RULE 26) Table 6. Composition of the concentrated solution (solution C) obtained after the discharge of germanium and yields of elution by elements

Table 7 shows the global loading and unloading performance of each element in the operation explained in example 4.

Table 7. Global loading and unloading performance of the Ge and main interfering elements

SUBSTITUTE SHEET (RULE 26) If the overall extraction performance of germanium is compared with that of the other elements, it can be seen that the only elements whose extraction yields are high are V and Mo, probably because they are both in anionic forms in solution. However, these elements have contents in the original liquid solution (L) of less than 0.5 mg / L and in the concentrated solution (C) of less than 1 mg / L. In the case of Sb, the main impurity in the extraction stage, it can be seen that the overall yield is 0.6%.

SUBSTITUTE SHEET (RULE 26)

Claims

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 the addition of a complexing reagent, subsequently carrying out a pH adjustment to reach the maximum stability of the complex. b) the contacting of the fertile solution with the exchange resin. The amount of resin, expressed in the form of equivalents, must be at least 2 times the number of equivalents of germanium. c) The separation of the resin from the resulting solution (refined, R). d) the discharge of germanium from the resin, putting it in contact with an aqueous acidic (HCI), basic (NaOH) or neutral (NaCI) solution, called eluent solution (E). e) the 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 or neutral solutions of high concentration, to reinstate the active groups, and condition it for its 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 catecoLGe molar 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.

SUBSTITUTE SHEET (RULE 26)

4. Method according to claim 1 characterized in that the process of extraction of the complex 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 containers of the stirred tank type .

6. 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 HCI, NaCl or NaOH, the concentration of which must be greater than 0.5 M.

8. 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) value whose maximum is 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.

10. 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.

SUBSTITUTE SHEET (RULE 26)

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 HCI or NaCI 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.

SUBSTITUTE SHEET (RULE 26) Summary

SUBSTITUTE SHEET (RULE 26)