Bisphosphonic acid extracting agent for extracting scandium as well as preparation method and application thereof

Abstract

The invention relates to a diphosphonic acid extracting agent for extracting scandium as well as a preparation method and application of the diphosphonic acid extracting agent. The extraction agent has a structure as shown in a formula 1. The extracting agent has two alpha-hydroxyalkyl phosphinic acid coordination functional groups, is high in chelating capacity, is slightly influenced by the acidity of a water phase, can still keep high scandium extraction capacity even in high-acidity waste liquid, can be used for enrichment and recovery of trace scandium ions in high-concentration waste acid, and is named as P, P '-[(imine) bis (methylene) bis [P-alpha-hydroxyalkyl phosphinic acid]. The extracting agent is formed by one-step reaction of alpha-hydroxyalkyl hypophosphorous acid and amine through Mannich reaction, is simple in synthesis method, good in stability and high in extraction capacity, has very good extraction performance on trace scandium in high-acidity and multi-impurity wastewater, can be widely applied to enrichment and recovery of scandium ions in acidic wastewater, and has a wide application prospect. And the extraction process has small loss and can be recycled.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy, and in particular relates to a diphosphonic acid extractant for extracting scandium, and a preparation method and application thereof. Background Art

[0002] Scandium and its compounds are widely used in high-tech fields as trace additives due to their excellent properties such as high melting point, high boiling point and low density, and are important strategic resources. However, scandium rarely has independent ores and is often associated with other minerals. Therefore, the raw materials for extracting scandium are mostly low-grade associated ores and secondary resources such as industrial waste slag and industrial wastewater. Most of them have problems such as scandium content being far lower than other elements, difficulty in extraction, and high cost.

[0003] Eighty percent of scandium oxide products in my country come from waste titanium dioxide acid produced during the production of titanium dioxide. At present, the main methods for recovering scandium from tailings and secondary resources are solvent extraction, adsorption, precipitation, etc. "A method for extracting scandium from waste titanium dioxide acid and red mud solution" (CN117004836A) discloses a method for adsorbing scandium from waste titanium dioxide acid and red mud solution using silicon-based tributyl phosphate resin. The adsorption method often uses ion exchange resin, which has high impurity removal efficiency, but limited loading capacity, and is only economically feasible when the impurity content is very low. The solvent extraction method has a large processing capacity, high efficiency, simple operation, and is easier to achieve large-scale industrialization. At present, the solvent extraction method has an unshakable position in the scandium recovery process. "A method for extracting scandium from coal gangue by concentrated sulfuric acid activation leaching" (CN109777972A) uses primary amine N1923 extractant to extract scandium from the ore pulp leachate. However, alkaline amine extractants are easy to emulsify and difficult to separate, so they are not suitable for industrial extraction of scandium. "A method for extracting scandium from fly ash" (CN106119555A) uses P350 extractant to extract scandium from fly ash, and the primary extraction rate is greater than 85%. However, the coordination ability of neutral extractants for scandium in a strongly acidic sulfuric acid system is relatively poor. Traditional acidic phosphoric acid extractants have problems with difficult stripping and lengthy washing processes in strongly acidic systems. Therefore, it is necessary to design an extractant that has good extraction performance for scandium ions in the presence of high acidity and trace amounts of scandium ions. Summary of the invention

[0004] The raw materials for extracting scandium are complex in composition, with high sulfuric acid concentration and low scandium content, which makes the recovery and purification of scandium extremely difficult. Traditional scandium extractants (P204, P507, P350, TBP, Cyanex273, etc.) generally have low application acidity, severe emulsification, and difficulty in stripping. In order to make up for the shortcomings of traditional extractants, the present invention designs a class of acidic, bidentate organic phosphoric acid extractants, P, P'-[(imine) di(methylene) di[P-α-hydroxyalkyl phosphinate]. The design of the bidentate structure enhances the chelation effect and improves the coordination ability of scandium. The electron-withdrawing effect of the P=O double bond enhances the acidity of -OH, increases the acidity of the extractant, and enhances the extraction ability, so that it can maintain high extraction performance for scandium in a high acidity environment. The presence of the alkyl chain increases the oil solubility, ensures the good oil solubility and metal loading capacity of the extractant, and minimizes the steric hindrance to the greatest extent, so that it can still have good extraction performance under the condition of very low scandium ion concentration.

[0005] The present invention discloses a method for preparing a bisphosphonic acid extractant for extracting scandium. The structure of the bisphosphonic acid extractant is shown in Formula 1:

[0006]

[0007] Formula 1: R 1 , R 2 Represents an alkyl chain

[0008] The preparation method of the extractant comprises the following steps:

[0009] S1: Add solvent, amine, α-hydroxyalkylphosphinic acid and inorganic acid in a three-necked round-bottom flask equipped with a mechanical stirrer and a condensation reflux device, and heat until the mixture becomes clear and transparent;

[0010] S2: Start to slowly add 37% formaldehyde solution or paraformaldehyde and continue the reaction at constant temperature for several hours;

[0011] S3: Remove the solvent, dissolve the obtained solid with dichloromethane, wash it with dilute hydrochloric acid and water three times in sequence, and obtain P,P'-[(imino)bis(methylene)bis[P-α-hydroxyalkylphosphinic acid] by rotary evaporation and vacuum drying.

[0012] According to an embodiment of the present invention, in Formula 1, R 1 , R 2 The same or different, are independently selected from substituted or unsubstituted C6-20 straight chain or branched alkyl.

[0013] According to an embodiment of the present invention, the solvent is selected from one or more of water and alcohol; preferably, the alcohol includes ethanol, propanol and isopropanol.

[0014] According to an embodiment of the present invention, the inorganic acid may be one of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid or acetic acid, preferably hydrochloric acid and sulfuric acid.

[0015] According to an embodiment of the present invention, the molar ratio of the amine to the α-hydroxyalkylphosphinic acid may be 1:1 to 1:4, preferably 1:2 to 1:3.

[0016] According to an embodiment of the present invention, the molar ratio of the amine to the inorganic acid may be 10:1 to 1:3, preferably 2:1 to 1:2.

[0017] According to an embodiment of the present invention, the molar ratio of the amine to formaldehyde may be 1:1 to 1:5, preferably 1:2 to 1:4.

[0018] According to an embodiment of the present invention, the reaction temperature may be 50 to 110° C., preferably 80 to 100° C., and the reaction time may be 1 to 10 h, preferably 4 to 8 h.

[0019] The present invention discloses a bisphosphonic acid extractant for extracting scandium, a preparation method and application thereof, and is characterized by comprising the following steps:

[0020] The diphosphonic acid extractant prepared with a diluent and a phase regulator is used as an organic phase, wherein the phase regulator is n-octanol, the diphosphonic acid extractant is N,N-amine di(α-hydroxyalkyl hypophosphorous acid), and the extractant concentration can be 0.01-0.5 mol / L; the aqueous phase and the organic phase are mixed and stirred, and the mixed solution after extraction is phase-separated to obtain an organic phase loaded with scandium ions and a raffinate ℃.

[0021] According to an embodiment of the present invention, Sc in the aqueous phase 3+ The concentration is 0.001~1g / L, and the sulfuric acid concentration is 0.01~5mol / L.

[0022] According to an embodiment of the present invention, the phase regulator is n-octanol, and the diphosphonic acid extractant is N,N-amine di(α-hydroxyalkyl hypophosphorous acid), and the concentration can be 0.01 to 0.5 mol / L, preferably 0.1 to 0.5 mol / L.

[0023] According to an embodiment of the present invention, the diluent may be one or more of an aliphatic hydrocarbon, a halogenated hydrocarbon, an aromatic hydrocarbon, a solvent oil and an alcohol. Preferably, the aliphatic hydrocarbon is one or more of n-hexane, cyclohexane and dodecane, and preferably, the halogenated hydrocarbon is one or more of dichloromethane, chloroform and 1,2-dichloroethane. Preferably, the aromatic hydrocarbon is one or more of toluene, xylene and 1,2,4-trimethylbenzene. Preferably, the solvent oil is one or more of S-100 solvent oil, S-150 solvent oil and S-260 solvent oil, and preferably, the alcohol is n-octanol.

[0024] According to an embodiment of the present invention, the ratio of the aqueous phase to the organic phase mixture can be 1:5-5:1, the extraction time can be 1 to 120 minutes, preferably 10 to 30 minutes; the extraction temperature can be 10 to 90°C, preferably 25 to 80°C.

[0025] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0026] (1) The extractant P,P'-[(imine)bis(methylene)bis[P-α-hydroxyalkylphosphinic acid] of the present invention has simple synthesis, high yield and is suitable for large-scale production.

[0027] (2) The extractant P,P'-[(imine)bis(methylene)bis[P-α-hydroxyalkylphosphinic acid] of the present invention has a bidentate structure design, which enhances chelation and improves the coordination ability to scandium. The electron-withdrawing effect of the P=O double bond enhances the acidity of -OH, increases the acidity of the extractant, and enhances the extraction ability, so that it can maintain high extraction performance for scandium in a high acidity environment. The presence of the alkyl chain increases the oil solubility, ensures the good oil solubility and metal loading capacity of the extractant, and minimizes the steric hindrance, so that it can still have good extraction performance under the condition of very low scandium ion concentration.

[0028] (3) The extractant used in the present invention has good thermal stability, is not easy to volatilize, and can be reused. All reagents used are low-priced, easy to obtain, and require a small amount of input, thereby saving costs.

[0029] (4) The extractant used in the present invention has no emulsification phenomenon, has fast phase separation and high production efficiency.

[0030] (5) The extractant used in the present invention does not need to be saponified when used and is an environmentally friendly extractant. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The following drawings merely illustrate certain embodiments of the present invention and should not be considered as limiting the scope of the invention.

[0032] Figure 1 Infrared spectra of P,P'-[(octylimine)bis(methylene)bis[P-α-hydroxyheptylphosphinic acid], P,P'-[(octylimine)bis(methylene)bis[P-α-hydroxyoctylphosphinic acid], and P,P'-[(octylimine)bis(methylene)bis[P-α-hydroxydecylphosphinic acid] provided in Examples 1, 2, and 3 of the present invention.

[0033] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of P,P'-[(octylimino)bis(methylene)bis[P-α-hydroxyheptylphosphinic acid] provided in Example 1 of the present invention.

[0034] Figure 3This is the hydrogen nuclear magnetic resonance spectrum of P,P'-[(octylimino)bis(methylene)bis[P-α-hydroxyoctylphosphinic acid] provided in Example 2 of the present invention.

[0035] Figure 4 This is the hydrogen nuclear magnetic resonance spectrum of P,P'-[(octylimino)bis(methylene)bis[P-α-hydroxydecylphosphinic acid] provided in Example 3 of the present invention. DETAILED DESCRIPTION

[0036] The extraction distribution ratio (D) and extraction rate (E) can intuitively show the extraction capacity of the extractant. D represents the ratio of the scandium ion concentration in the aqueous phase and the organic phase after extraction, and E represents the ratio of the scandium ion concentration in the aqueous phase before and after extraction. The concentration of scandium ions in this patent is determined by ICP-OES.

[0037] The present invention is described in detail below with reference to specific embodiments, but the protection scope of the present invention is not limited by the embodiments.

[0038] Example 1

[0039] In a three-necked round-bottom flask equipped with a mechanical stirrer and a condensation reflux device, water, 6.46g of n-octylamine, 10.80g of α-hydroxyheptylphosphinic acid and 0.36mL of hydrochloric acid were added in sequence, and heated to 50°C. After the mixture became clear and transparent, 15.00mL of 37% formaldehyde solution was slowly added. After the constant temperature reaction was continued for 4h, the upper aqueous phase was removed, and the lower colloid was dissolved with 30mL of dichloromethane. Washed with appropriate amounts of dilute hydrochloric acid and water several times in sequence, and 18.21g of the product was obtained by rotary evaporation and vacuum drying.

[0040] Example 2

[0041] In a three-necked round-bottom flask equipped with a mechanical stirrer and a condensation reflux device, water, 6.46g of n-octylamine, 19.40g of α-hydroxyoctylphosphinic acid and 0.36mL of hydrochloric acid were added in sequence, and heated to 50°C. After the mixture became clear and transparent, 15.00mL of 37% formaldehyde solution was slowly added. After the constant temperature reaction was continued for 8h, the upper aqueous phase was removed, and the lower colloid was dissolved with 50mL of dichloromethane. Washed with appropriate amounts of dilute hydrochloric acid and water several times in sequence, and 20.66g of the product was obtained by rotary evaporation and vacuum drying.

[0042] Example 3

[0043] In a three-necked round-bottom flask equipped with a mechanical stirrer and a condensation reflux device, water, 6.46g of n-octylamine, 22.20g of α-hydroxydecylphosphinic acid and 0.36mL of hydrochloric acid were added in sequence, and heated to 50°C. After the mixture became clear and transparent, 15.00mL of 37% formaldehyde solution was slowly added. After the constant temperature reaction was continued for 7h, the upper aqueous phase was removed, and the lower colloid was dissolved with 30mL of dichloromethane. Washed with appropriate amounts of dilute hydrochloric acid and water several times in sequence, and 19.86g of the product was obtained by rotary evaporation and vacuum drying.

[0044] Example 4

[0045] In a three-necked round-bottom flask equipped with a mechanical stirrer and a condensation reflux device, water, 9.27g dodecylamine, 18.00g α-hydroxyheptylphosphinic acid and 0.6mL hydrochloric acid were added in sequence, and heated to 50°C. After the mixture became clear and transparent, 15.00mL of 37% formaldehyde solution was slowly added. After the constant temperature reaction was continued for 7h, the upper aqueous phase was removed, and the lower colloid was dissolved with 50mL of dichloromethane. Washed with appropriate amounts of dilute hydrochloric acid and water several times in sequence, and 22.06g of the product was obtained by rotary evaporation and vacuum drying.

[0046] Example 5

[0047] In a three-necked round-bottom flask equipped with a mechanical stirrer and a condensation reflux device, water, 12.07g hexadecylamine, 18.00g α-hydroxyheptylphosphinic acid and 0.6mL hydrochloric acid were added in sequence, and heated to 50°C. After the mixture became clear and transparent, 15.00mL of 37% formaldehyde solution was slowly added. After the constant temperature reaction for 7h, the upper aqueous phase was removed, and the lower colloid was dissolved with 60mL dichloromethane. Washed with appropriate amount of dilute hydrochloric acid and water several times in sequence, and 27.04g of the product was obtained by rotary evaporation and vacuum drying.

[0048] Example 6

[0049] In a three-necked round-bottom flask equipped with a mechanical stirrer and a condensation reflux device, water, 13.48g of octadecylamine, 18.00g of α-hydroxyheptylphosphinic acid and 0.6mL of hydrochloric acid were added in sequence, and heated to 50°C. After the mixture became clear and transparent, 15.00mL of 37% formaldehyde solution was slowly added. After the constant temperature reaction was continued for 7h, the upper aqueous phase was removed, and the lower colloid was dissolved with 50mL of dichloromethane. Washed with appropriate amounts of dilute hydrochloric acid and water several times in sequence, and 22.65g of the product was obtained by rotary evaporation and vacuum drying.

[0050] Example 7

[0051] In a three-necked round-bottom flask equipped with a mechanical stirrer and a condensation reflux device, ethanol, 6.46g of n-octylamine, 9.00g of α-hydroxyheptylphosphinic acid and 0.36mL of hydrochloric acid were added in sequence, and heated to 60°C. After the mixture became clear and transparent, 15.00mL of 37% formaldehyde solution was slowly added. After the constant temperature reaction was continued for 7h, the ethanol was removed by rotary evaporation, and the lower layer of colloid was dissolved with 50mL of dichloromethane. Washed with appropriate amount of dilute hydrochloric acid and water several times in sequence, and 24.16g of the product was obtained by rotary evaporation and vacuum drying.

[0052] Example 8

[0053] In a three-necked round-bottom flask equipped with a mechanical stirrer and a condensation reflux device, water, 12.92g of n-octylamine, 18.00g of α-hydroxyheptylphosphinic acid and 0.36mL of hydrochloric acid were added in sequence, and heated to 80°C. After the mixture became clear and transparent, 15.00mL of 37% formaldehyde solution was slowly added. After the constant temperature reaction was continued for 7h, the upper aqueous phase was removed, and the lower colloid was dissolved with 60mL of dichloromethane. Washed with appropriate amounts of dilute hydrochloric acid and water several times in sequence, 36.85g of the product was obtained by rotary evaporation and vacuum drying.

[0054] Example 9

[0055] In a three-necked round-bottom flask equipped with a mechanical stirrer and a condensation reflux device, water, 12.92g of n-octylamine, 18.00g of α-hydroxyheptylphosphinic acid and 0.36mL of sulfuric acid were added in sequence, and heated to 80°C. After the mixture became clear and transparent, 15.00mL of 37% formaldehyde solution was slowly added. After the constant temperature reaction was continued for 7h, the upper aqueous phase was removed, and the lower colloid was dissolved with 100mL of dichloromethane. Washed with appropriate amounts of dilute hydrochloric acid and water several times in sequence, 42.95g was obtained by rotary evaporation and vacuum drying.

[0056] Example 10

[0057] In a three-necked round-bottom flask equipped with a mechanical stirrer and a condensation reflux device, water, 25.85g of n-octylamine, 72.00g of α-hydroxyheptylphosphinic acid and 0.72mL of sulfuric acid were added in sequence, and heated to 100°C. After the mixture became clear and transparent, 15.00mL of 37% formaldehyde solution was slowly added. After the reaction was continued at a constant temperature for 10 hours, the upper aqueous phase was removed, and the lower colloid was dissolved with 200mL of dichloromethane. The product was washed several times with appropriate amounts of dilute hydrochloric acid and water in sequence, and 94.6g of the product was obtained by rotary evaporation and vacuum drying.

[0058] Embodiment 11

[0059] In a three-necked round-bottom flask equipped with a mechanical stirrer and a condensation reflux device, water, 6.46g of n-octylamine + 9.27g of dodecylamine, 36.00g of α-hydroxyheptylphosphinic acid and 0.36mL of sulfuric acid were added in sequence, and heated to 80°C. After the mixture became clear and transparent, 15.00mL of 37% formaldehyde solution was slowly added. After the constant temperature reaction was continued for 10 hours, the upper aqueous phase was removed, and the lower colloid was dissolved with 50mL of dichloromethane. Washed with appropriate amounts of dilute hydrochloric acid and water several times in sequence, and 27.05g of the product was obtained by rotary evaporation and vacuum drying.

[0060] Example 12

[0061] Sc in water 3+ The concentration is 1g / L, and the concentration of sulfuric acid is 3mol / L. Prepare 0.01mol / L P,P'-[(octyl imine) di(methylene) di[P-α-hydroxyheptyl phosphinic acid], P,P'-[(dodecyl imine) di(methylene) di[P-α-hydroxyheptyl phosphinic acid], P,P'-[(hexadecyl imine) di(methylene) di[P-α-hydroxyheptyl phosphinic acid], P,P'-[(octadecyl imine) di(methylene) di[P-α-hydroxyheptyl phosphinic acid], P,P'-[(octadecyl imine) di(methylene) di[P-α-hydroxyheptyl phosphinic acid], P,P'-[(octadecyl imine) di(methylene) di[P-α-hydroxyheptyl phosphinic acid] or P,P'-[(octyl imine) di(methylene) di[P-α-hydroxyoctyl phosphinic acid] with a diluent and 20% n-octanol as the organic phase, and the diluent is S-260 solvent oil. 5 mL of the aqueous phase and the organic phase were mixed, the extraction time was 30 min, the extraction temperature was 25 °C, and the Sc in the raffinate was determined. 3+ The effects of the concentration of the extractant on the extraction rate are shown in Table 1.

[0062] Comparative Example

[0063] Sc in water 3+ The concentration is 1g / L, and the sulfuric acid concentration is 3mol / L. P204, P507, Cyanex 272, TOPO and TBP are prepared with 0.01mol / L diluent and 20% n-octanol as organic phase, and the diluent is S-260 solvent oil. 5mL of aqueous phase and organic phase are mixed, the extraction time is 30min, the extraction temperature is 25℃, and the Sc in the raffinate is determined. 3+ The effects of the concentration of the extractant on the extraction rate are shown in Table 1.

[0064] Table 1

[0065]

Claims

1. A bisphosphonic acid extractant for extracting scandium, wherein the structure of the bisphosphonic acid extractant is as shown in Formula 1: Formula 1: R1 and R2 represent alkyl chains It is characterized in that The preparation method comprises the following steps: S1: Add solvent, amine, α-hydroxyalkylphosphinic acid and inorganic acid in a three-necked round-bottom flask equipped with a mechanical stirrer and a condensation reflux device, and heat until the mixture becomes clear and transparent; S2: Start to slowly add 37% formaldehyde solution or paraformaldehyde and continue the reaction at constant temperature for several hours; S3: Remove the solvent, dissolve the obtained solid with dichloromethane, wash it with dilute hydrochloric acid and water three times in sequence, and obtain P,P'-[(imino)bis(methylene)bis[P-α-hydroxyalkylphosphinic acid] by rotary evaporation and vacuum drying.

2. A method for preparing a bisphosphonic acid extractant for extracting scandium according to claim 1, characterized in that: In Formula 1, R1 and R2 are the same or different and are independently selected from substituted or unsubstituted C7-18 straight or branched alkyl groups.

3. A method for preparing a bisphosphonic acid extractant for extracting scandium according to claim 1, characterized in that: In the step, the solvent is selected from one or more of water and alcohol; preferably, the alcohol includes ethanol, propanol and isopropanol.

4. A method for preparing a bisphosphonic acid extractant for extracting scandium according to claim 1, characterized in that: In the step, the inorganic acid is selected from one of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid or acetic acid.

5. A method for preparing a bisphosphonic acid extractant for extracting scandium according to claim 1, characterized in that: In the steps, the molar ratio of the amine to the α-hydroxyalkylphosphinic acid is 1:1 to 1:

4.

6. A method for preparing a bisphosphonic acid extractant for extracting scandium according to claim 1, characterized in that: In the steps, the molar ratio of amine to inorganic acid is 10:1 to 1:

3.

7. A method for preparing a bisphosphonic acid extractant for extracting scandium according to claim 1, characterized in that: In the steps, the molar ratio of amine to formaldehyde is 1:1 to 1:

5.

8. A method for preparing a bisphosphonic acid extractant for extracting scandium according to claim 1, characterized in that: In the steps, the reaction temperature is 40 to 120° C., and the reaction time is 1 to 10 hours.

9. A bisphosphonic acid extractant for extracting scandium and its preparation method and application, wherein the aqueous phase contains Sc 3+ The concentration is 0.001-1 g / L, and the sulfuric acid concentration is 0.01-5 mol / L; it is characterized by comprising the following steps: S1: The diphosphonic acid extractant prepared with a diluent and a phase regulator is an organic phase, and the diluent is one or more of aliphatic hydrocarbons, halogenated hydrocarbons, aromatic hydrocarbons, solvent oils and alcohols; preferably, the aliphatic hydrocarbons are one or more of n-hexane, cyclohexane and dodecane, and preferably, the halogenated hydrocarbons are one or more of dichloromethane, chloroform and 1,2-dichloroethane. Preferably, the aromatic hydrocarbons are one or more of toluene, xylene and 1,2,4-trimethylbenzene; preferably, the solvent oil is one or more of S-100 solvent oil, S-150 solvent oil and S-260 solvent oil, and preferably, the alcohol is n-octanol. The diphosphonic acid extractant is the extractant in claim 1, and the concentration of the extractant is 0.01-0.5 mol / L; S2: Mix the aqueous phase and the organic phase, the ratio of the aqueous phase to the organic phase is 1:5-5:1, the extraction time is 1-120 min, the extraction temperature is 10-90°C, and the mixed solution after extraction is phase-separated to obtain the organic phase loaded with scandium ions and the raffinate.

Images