Preparation method and application of amino diphosphinic acid

Abstract

The invention belongs to the technical field of synthesis of extraction agents, and particularly relates to a preparation method and application of amido diphosphinic acid. The preparation method comprises the following steps: (1) mixing a solvent, primary amine, cyclohexylphosphinic acid and inorganic acid, and heating until the solution is clear and transparent; (2) adding a formaldehyde solution or paraformaldehyde into the clear and transparent solution for reaction; and (3) removing a water phase from the mixture obtained after the reaction in the step (2) is finished, dissolving jelly obtained after the water phase is removed by using dichloromethane, and carrying out washing, rotary evaporation and drying to obtain the amido diphosphinic acid.

Description

Technical Field

[0001] This application belongs to the field of extractant synthesis technology, specifically a method for preparing and applying an amino-based diphosphonic acid. Background Technology

[0002] The wet-process preparation of phosphoric acid mainly uses the sulfuric acid process (dihydrate, hemihydrate, and anhydrous processes), which is mature and widely adopted. However, iron impurities in the raw materials increase the difficulty of phosphoric acid purification, hindering the high-value utilization of phosphoric acid. In hydrometallurgy, precipitation (requiring large amounts of reagents and prone to secondary pollution) and adsorption (suitable only for low impurity concentrations) each have limitations in removing impurities. Solvent extraction, due to its large processing capacity, high separation efficiency, and ease of control, is more suitable for industrial application, making its use for iron removal a research focus. The patent "A method for extracting and separating iron and phosphorus from ferric phosphate slag to prepare ferric phosphate" (CN 114804048 A) discloses a method for extracting and separating iron from the acid leaching solution of ferric phosphate slag using P204. This method requires the pH of the extraction system to be strictly around 1, which is unsuitable for the low pH generated by the high concentrations of sulfuric acid and phosphoric acid in wet-process phosphoric acid solutions. Another patent, "A Combined Extraction Method for Producing High-Quality Phosphoric Acid" (CN106145075 A), proposes a two-stage design of "removing impurities first and then extracting acid." This method uses P204 extractant to preferentially remove metal ions, followed by extraction of phosphoric acid using a TBP-MIBK composite system, effectively avoiding the double concentration problem of traditional processes. However, the dual extraction system leads to a complex process flow, higher equipment investment costs, and strict requirements for automation control. Furthermore, P204 has limited selectivity for specific metal ions in a strongly acidic environment, which may cause co-extraction and affect the purity of the final product.

[0003] Furthermore, traditional extractants for treating high-acid wet-process phosphoric acid systems suffer from fundamental problems: basic amines readily extract phosphoric acid, leading to losses; neutral extractants have weak coordination ability with iron; and traditional acidic extractants suffer from limited protonation and decreased efficiency under high acid conditions. Due to the high acidity and complex composition of wet-process phosphoric acid, efficient separation of iron impurities remains a bottleneck in the industry. Developing novel extractants that are adaptable to strong acids, highly selective for iron, and do not require extensive co-extraction of phosphoric acid is a key direction for overcoming the current predicament. Summary of the Invention

[0004] To address the problems of the prior art, this application provides a method for preparing and applying an amino-based diphosphonic acid, which is achieved through the following scheme: An amino-based diphosphonic acid, wherein the structural formula of the amino-based diphosphonic acid is: or In the formula, R1 is cyclohexyl or phenyl or 9-octadecenyl or a straight-chain alkyl group having 6 to 20 carbon atoms, and R2 and / or R4 are straight-chain alkyl groups having 6 to 12 carbon atoms.

[0005] A method for preparing amino-based bisphosphonic acid, comprising the following steps: (1) mixing solvent, primary amine, cyclohexylphosphonic acid and inorganic acid, and heating until the solution is clear and transparent; (2) adding formaldehyde solution or paraformaldehyde to the clear and transparent solution for reaction; (3) removing the aqueous phase from the mixture after the reaction in step (2), dissolving the gelatinous substance after removing the aqueous phase with dichloromethane, and obtaining amino-based bisphosphonic acid by washing, rotary evaporation and drying; the reaction equation for the preparation of amino-based bisphosphonic acid is as follows: .

[0006] Furthermore, the solvent mentioned in step (1) is one or more of water, methanol, ethanol, propanol, and isopropanol; the primary amine is one or more of cyclohexylamine, aniline, oleylamine, straight-chain primary amines with 6 to 20 carbon atoms, and primary amine N1923; the inorganic acid is one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, or acetic acid.

[0007] Furthermore, the molar ratio of the primary amine to cyclohexylphosphonic acid can be 1:1 to 1:5; the molar ratio of the primary amine to the inorganic acid can be 10:1 to 1:5; the mass ratio of water to the primary amine can be 3:1 to 15:1; and the molar ratio of the primary amine to the formaldehyde solution is 1:1 to 1:5.

[0008] Furthermore, the heating temperature in step (1) is 50~110℃. o C; The reaction temperature in step (2) is 50~100℃ o C, the reaction time is 1~12h.

[0009] Application of prepared amino-based diphosphonic acid in the extraction of iron from wet phosphoric acid solution.

[0010] Furthermore, the Fe in the wet-process phosphoric acid solution 3+ The concentrations are 0.1~6.5 g / L, sulfuric acid concentrations are 0.01~5 mol / L, and phosphoric acid concentrations are 0.5~8 mol / L.

[0011] Furthermore, the extraction steps are as follows: (1) Use amino-diphosphonic acid prepared with diluent and phase conditioning agent as the organic phase, and the concentration of amino-diphosphonic acid in the organic phase is 0.01~1 mol / L; (2) Preheat the organic phase and wet phosphoric acid solution separately, mix and stir for extraction, and separate the extracted mixed solution to obtain an iron-loaded organic phase and raffinate; (3) Back-extract the iron-loaded organic phase with a back-extracting agent at a back-extraction temperature of 15~80°C. o C, yields an aqueous solution containing iron ions.

[0012] Furthermore, the diluent and phase modifier mentioned in step (1) are one or more of aliphatic hydrocarbons, halogenated hydrocarbons, aromatic hydrocarbons, solvent oils, and alcohols; the volume ratio of wet phosphoric acid solution to organic phase mentioned in step (2) is 1:5 to 5:1, the extraction time is 1 to 120 min, and the extraction temperature is 10 to 90 °C. o C; In step (3), the stripping agent is 0.1~1 mol / L ammonium oxalate, and the stripping time is 10~120 min.

[0013] Beneficial effects: (1) The amino diphosphonic acid extracted from iron in wet phosphoric acid in this invention is simple to prepare, has a high yield, and can be mass-produced; the cyclohexyl group ensures that the extractant has good oil solubility while greatly reducing the loss during high-temperature extraction.

[0014] (2) The present invention uses amino diphosphonic acid as an extractant, which has excellent extraction efficiency for iron in the wet phosphoric acid system, and can achieve deep removal of iron without changing the original wet phosphoric acid process. The overall extraction performance is significantly better than traditional phosphoric (phosphine) extractants such as P204, P507, and Cyanex272.

[0015] (3) The amino diphosphonic acid extracted from iron in wet phosphoric acid in this invention has good thermal stability, is not easily volatilized, and can be reused. All the reagents used are inexpensive, readily available, and require only a small amount, which can effectively control costs.

[0016] (4) When using the present invention to extract amine diphosphonic acid from ferric phosphoric acid in wet process, there is no emulsification, the phase separation rate is fast, and the production efficiency is high. Compared with common phosphorus (phosphine) extractants, this extractant does not require saponification and is an environmentally friendly extractant. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some preferred embodiments of this application, and not all embodiments. For those skilled in the art, other embodiments and drawings can be obtained based on these embodiments and drawings without creative effort, and all of them fall within the protection scope of this application.

[0018] Figure 1 The nuclear magnetic resonance spectrum of amino diphosphonic acid extracted from iron in wet-process phosphoric acid prepared in Example 4; Figure 2 The infrared spectrum of amino diphosphonic acid extracted from iron in wet-process phosphoric acid prepared in Example 4. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below. It should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. The foregoing definitions are only for the convenience of describing this application and simplifying the description, and are not intended to indicate or imply that the structure referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0020] Example 1 (1) In a 500 mL three-necked round-bottom flask equipped with a mechanical stirrer and a reflux condenser, add 150 mL of water, 0.25 mol of octylamine, 0.25 mol of cyclohexylphosphonic acid and 0.5 mol of hydrochloric acid in sequence, and heat to 75°C. o C, The mixture is clear and transparent; (2) Add 0.5 mol of 37% formaldehyde solution to the clear and transparent solution from step (1), 75 o The reaction was carried out at a constant temperature for 4 hours under C conditions. (3) After the reaction in step (2) is completed, the upper aqueous phase is removed, the gel-like substance after removing the aqueous phase is dissolved in dichloromethane, washed with dilute hydrochloric acid and water in sequence, rotary evaporated, and vacuum dried to obtain amino diphosphonic acid (P,P'-[(octylamine)bis(methylene)]bis[p-cyclohexylphosphonic acid]) from the extraction of iron from wet phosphoric acid.

[0021] Example 2 (1) In a 500 mL three-necked round-bottom flask equipped with a mechanical stirrer and a reflux condenser, add 150 mL of water, 0.25 mol of octylamine, 0.5 mol of cyclohexylphosphonic acid and 0.25 mol of hydrochloric acid in sequence, mix, and heat to 90°C. o C, The mixture is clear and transparent; (2) Add 1 mol of 37% formaldehyde solution to the clear and transparent solution from step (1), 90 o The reaction was carried out at a constant temperature for 5 hours under C conditions. (3) After the reaction in step (2) is completed, the upper aqueous phase is removed, the gel-like substance after removing the aqueous phase is dissolved in dichloromethane, washed with dilute hydrochloric acid and water in sequence, rotary evaporated, and vacuum dried to obtain amino diphosphonic acid (P,P'-[(octylamine)bis(methylene)]bis[p-cyclohexylphosphonic acid]) from the extraction of iron from wet phosphoric acid.

[0022] Example 3 (1) In a 500 mL three-necked round-bottom flask equipped with a mechanical stirrer and a reflux condenser, add 150 mL of water, 0.25 mol of octylamine, 0.5 mol of cyclohexylphosphonic acid and 0.25 mol of sulfuric acid in sequence, mix, and heat to 80 °C. o C, The mixture is clear and transparent; (2) Add 0.5 mol of 37% formaldehyde solution to the clear and transparent solution from step (1), 80 o The reaction was carried out at a constant temperature for 7 hours under C conditions. (3) After the reaction in step (2) is completed, the upper aqueous phase is removed, the gel-like substance after removing the aqueous phase is dissolved in dichloromethane, washed with dilute hydrochloric acid and water in sequence, rotary evaporated, and vacuum dried to obtain amino diphosphonic acid (P,P'-[(octylamine)bis(methylene)]bis[p-cyclohexylphosphonic acid]) from the extraction of iron from wet phosphoric acid.

[0023] Example 4 (1) In a 500 mL three-necked round-bottom flask equipped with a mechanical stirrer and a reflux condenser, add 150 mL of 0.25 mol of octylamine, 0.6 mol of cyclohexylphosphonic acid, and 0.1 mol of sulfuric acid in sequence, mix, and heat to 100 °C. o C, The mixture is clear and transparent; (2) Add 0.75 mol of 37% formaldehyde solution to the clear and transparent solution from step (1), 100 o The reaction was carried out at a constant temperature for 6 hours under C conditions. (3) After the reaction in step (2) is completed, the upper aqueous phase is removed, the gel-like substance after removing the aqueous phase is dissolved in dichloromethane, washed with dilute hydrochloric acid and water in sequence, rotary evaporated, and vacuum dried to obtain amino diphosphonic acid (P,P'-[(octylamine)bis(methylene)]bis[p-cyclohexylphosphonic acid]) from the extraction of iron from wet phosphoric acid.

[0024] Example 5 (1) In a 500 mL three-necked round-bottom flask equipped with a mechanical stirrer and a reflux condenser, add 150 mL of 0.25 mol of octylamine, 0.75 mol of cyclohexylphosphonic acid, and 0.25 mol of sulfuric acid in sequence, mix, and heat to 110 °C. o C, The mixture is clear and transparent; (2) Add 1 mol of 37% formaldehyde solution to the clear and transparent solution from step (1), 110 o The reaction was carried out at a constant temperature for 8 hours under C conditions. (3) After the reaction in step (2) is completed, the upper aqueous phase is removed, the gel-like substance after removing the aqueous phase is dissolved in dichloromethane, washed with dilute hydrochloric acid and water in sequence, rotary evaporated, and vacuum dried to obtain amino diphosphonic acid (P,P'-[(octylamine)bis(methylene)]bis[p-cyclohexylphosphonic acid]) from the extraction of iron from wet phosphoric acid.

[0025] The raw materials and yields of the aminophosphonic acids for extracting iron from wet-process phosphoric acid prepared in Examples 1-5 are shown in Table 1 below: Table 1 The 1H NMR spectrum and IR spectrum of the aminophosphonic acid extracted from iron in wet-process phosphoric acid prepared in Example 4 are shown below. Figure 1 and Figure 2 As shown.

[0026] P,P'-[(octylamine)bis(methylene)]bis[p-cyclohexylphosphonic acid]: 1 H NMR(400 MHz, Chloroform-d) δ 3.49(d,J=5.6 Hz, 4H), 2.08–1.07(m, 36H), 0.87(t, 3H). IR(KBr, cm -1 ) υ -CH3 (movie) / cm -1 2953; υ -CH2- (movie) / cm -1 2855; υ P-CH2- (movie) / cm -1 1452; υ P=O (movie) / cm -1 1173; υ C-N (movie) / cm -1 1055; υ P-O-H (movie) / cm -1 957. Example 6 (1) Prepare 0.3 mol / L aminophosphonic acid as the organic phase for extracting iron from wet phosphoric acid using diluent and 10% n-octanol (phase modifier). The diluents used are 1,2,4-trimethylbenzene, S-150 solvent oil and S-260 solvent oil, respectively. (2) Mix 25 mL of the organic phase from step (1) with 25 mL of wet phosphoric acid solution (aqueous phase) and stir to extract for 10 min at a temperature of 25°C. o C. After extraction, the mixed solution is separated to obtain an iron-loaded organic phase and a raffinate; the Fe content in the raffinate is determined. 3+ Concentration (Fe) 3+ The concentrations were all less than 0.046 g / L. The extraction rate (E) was calculated according to formula (1). The effect of the diluent on the extraction rate is shown in Table 2. Table 2 (3) The iron-loaded organic phase is back-extracted with ammonium oxalate at a temperature of 40°C. o C, the back-extraction time is 30 min, resulting in an aqueous solution containing iron ions, of which Fe 3+ The concentrations were all greater than 1.94 g / L. The back-extraction rate (S) was calculated according to formula (2), and the back-extraction rate of iron was greater than 99%.

[0027] Example 7 (1) Prepare 0.3 mol / L amino diphosphonic acid for extracting iron from wet phosphoric acid using S-260 solvent oil diluent and 10% n-octanol (phase modifier) ​​as the organic phase; (2) Mix 25 mL of the organic phase from step (1) with 25 mL of wet phosphoric acid solution (aqueous phase) and stir to extract for 15 min at a temperature of 45°C. o C. After extraction, the mixed solution is separated to obtain an iron-loaded organic phase and a raffinate; the Fe content in the raffinate is determined. 3+ Concentration (Fe) 3+ The concentration was 0.056 g / L. The extraction rate (E) was calculated according to formula (1). The extraction results are shown in Table 3. (3) The organic phase loaded with iron ions was back-extracted with ammonium oxalate at a temperature of 40°C for 30 min to obtain an aqueous solution containing iron ions, wherein Fe 3+ The concentration is 1.95 g / L. The back-extraction rate (S) is calculated according to formula (2), and the back-extraction rate of iron is greater than 99%.

[0028] Example 8 (1) Prepare 0.3 mol / L amino diphosphonic acid for extracting iron from wet phosphoric acid using S-260 solvent oil diluent and 10% n-octanol (phase modifier) ​​as the organic phase; (2) Mix 25 mL of the organic phase from step (1) with 25 mL of wet phosphoric acid solution (aqueous phase) and stir to extract for 15 min at 55 °C. After extraction, the mixed solution is separated to obtain an organic phase loaded with iron ions and a raffinate. The Fe content in the raffinate is then determined. 3+ Concentration (Fe) 3+ The concentration was 0.072 g / L. The extraction rate (E) was calculated according to formula (1). The extraction results are shown in Table 3. (3) The organic phase loaded with iron ions was back-extracted with ammonium oxalate at a temperature of 40°C for 30 min to obtain an aqueous solution containing iron ions, wherein Fe 3+ The concentration is 1.91 g / L. The back-extraction rate (S) is calculated according to formula (2), and the back-extraction rate of iron is greater than 99%.

[0029] Example 9 (1) Prepare 0.3 mol / L amino diphosphonic acid for extracting iron from wet phosphoric acid using S-260 solvent oil diluent and 10% n-octanol (phase modifier) ​​as the organic phase; (2) Mix 30 mL of the organic phase from step (1) with 10 mL of wet phosphoric acid solution (aqueous phase) and stir to extract for 15 min at 65 °C. After extraction, the mixed solution is separated to obtain an organic phase loaded with iron ions and a raffinate. The Fe content in the raffinate is then determined. 3+ Concentration (Fe) 3+ The concentration was 0.01 g / L. The extraction rate (E) was calculated according to formula (1). The extraction results are shown in Table 3. (3) The organic phase loaded with iron ions was back-extracted with ammonium oxalate at a temperature of 40°C for 30 min to obtain an aqueous solution containing iron ions, wherein Fe 3+ The concentration is 1.98 g / L. The back-extraction rate (S) is calculated according to formula (2), and the back-extraction rate of iron is greater than 99%.

[0030] Example 10 (1) Prepare 0.3 mol / L amino diphosphonic acid for extracting iron from wet phosphoric acid using S-260 solvent oil diluent and 10% n-octanol (phase modifier) ​​as the organic phase; (2) Mix 10 mL of the organic phase from step (1) with 30 mL of wet phosphoric acid solution (aqueous phase) and stir to extract for 15 min at 75 °C. After extraction, the mixed solution is separated to obtain an organic phase loaded with iron ions and a raffinate. The Fe content in the raffinate is then determined. 3+ Concentration (Fe) 3+ The concentration was 0.95 g / L. The extraction rate (E) was calculated according to formula (1). The extraction results are shown in Table 3. (3) The organic phase loaded with iron ions was back-extracted with ammonium oxalate at a temperature of 40°C for 30 min to obtain an aqueous solution containing iron ions, wherein Fe 3+ The concentration is 1.04 g / L. The back-extraction rate (S) is calculated according to formula (2), and the back-extraction rate of iron is greater than 99%.

[0031] Examples 7-10: Extraction of iron-containing amino diphosphonic acid from wet-process phosphoric acid for Fe in wet-process phosphoric acid solution 3+ The extraction rates are shown in Table 3 below: Table 3 Example 11 (1) Prepare 0.3 mol / L amino diphosphonic acid for extracting iron from wet phosphoric acid using S-260 solvent oil diluent and 10% n-octanol (phase modifier) ​​as the organic phase; (2) Mix 25 mL of the organic phase from step (1) with 25 mL of wet phosphoric acid solution (aqueous phase) for extraction. After extraction, the mixed solution is separated to obtain an organic phase loaded with iron ions and a raffinate (aqueous phase). The extraction time is 5 min and the extraction temperature is 25 °C. The Fe content in the raffinate is measured. 3+ Concentration (Fe) 3+ The concentration was 0.27 g / L. The extraction rate (E) was calculated according to formula (1). The extraction results are shown in Table 4. (3) The organic phase loaded with iron ions was back-extracted with ammonium oxalate at a temperature of 40 °C for 30 min to obtain an aqueous solution containing iron ions, wherein Fe 3+ The concentration is 1.72 g / L. The back-extraction rate (S) is calculated according to formula (2), and the back-extraction rate of iron is greater than 99%.

[0032] Example 12 (1) Prepare 0.3 mol / L amino diphosphonic acid for extracting iron from wet phosphoric acid using S-260 solvent oil diluent and 10% n-octanol (phase modifier) ​​as the organic phase; (2) Mix 25 mL of the organic phase from step (1) with 25 mL of wet phosphoric acid solution (aqueous phase) for extraction. After extraction, the mixed solution is separated to obtain an organic phase loaded with iron ions and a raffinate (aqueous phase). The extraction time is 15 min and the extraction temperature is 25 °C. The Fe content in the raffinate is measured. 3+ Concentration (Fe) 3+ The concentration was 0.014 g / L. The extraction rate (E) was calculated according to formula (1). The extraction results are shown in Table 4. (3) The organic phase loaded with iron ions was back-extracted with ammonium oxalate at a temperature of 40°C for 30 min to obtain an aqueous solution containing iron ions, wherein Fe 3+ The concentration is 1.97 g / L. The back-extraction rate (S) is calculated according to formula (2), and the back-extraction rate of iron is greater than 99%.

[0033] Example 13 (1) Prepare 0.1 mol / L aminophosphonic acid for extracting iron from wet-process phosphoric acid using S-260 solvent oil diluent and 10% n-octanol (phase modifier) ​​as the organic phase; (2) Mix 25 mL of the organic phase from step (1) with 25 mL of wet phosphoric acid solution (aqueous phase) for extraction. After extraction, the mixed solution is separated to obtain an organic phase loaded with iron ions and a raffinate (aqueous phase). The extraction time is 10 min and the extraction temperature is 25 °C. The Fe content in the raffinate is measured. 3+ Concentration (Fe) 3+ The concentration was 0.88 g / L. The extraction rate (E) was calculated according to formula (1). The extraction results are shown in Table 4. (3) The organic phase loaded with iron ions was back-extracted with ammonium oxalate at a temperature of 40°C for 30 min to obtain an aqueous solution containing iron ions, wherein Fe 3+ The concentration is 1.12 g / L. The back-extraction rate (S) is calculated according to formula (2), and the back-extraction rate of iron is greater than 99%.

[0034] Example 14 (1) Prepare 0.1 mol / L aminophosphonic acid for extracting iron from wet-process phosphoric acid using S-260 solvent oil diluent and 10% n-octanol (phase modifier) ​​as the organic phase; (2) Mix 25 mL of the organic phase from step (1) with 25 mL of wet phosphoric acid solution (aqueous phase) for extraction. After extraction, the mixed solution is separated to obtain an organic phase loaded with iron ions and a raffinate (aqueous phase). The extraction time is 10 min and the extraction temperature is 25 °C. The Fe content in the raffinate is measured. 3+ Concentration (Fe) 3+ The concentration was 0.45 g / L. The extraction rate (E) was calculated according to formula (1). The extraction results are shown in Table 4. (3) The organic phase loaded with iron ions was back-extracted with ammonium oxalate at a temperature of 40°C for 30 min to obtain an aqueous solution containing iron ions, wherein Fe 3+ The concentration is 1.54 g / L. The back-extraction rate (S) is calculated according to formula (2), and the back-extraction rate of iron is greater than 99%.

[0035] Table 4 Comparative Example 1 (1) A solution of D2EHPA, P538, PC-88A, naphthenic acid, CA-12, Cyanex272, TOPO and TBP with a concentration of 0.3 mol / L was prepared using S-260 solvent oil as a diluent, and used as the organic phase. The organic phase and wet phosphoric acid solution were mixed at a volume ratio of 5:1 and extracted for 30 min at a temperature of 25 °C. After extraction, the mixed solution was separated to obtain an organic phase loaded with iron and aluminum ions and a raffinate. The Fe content in the raffinate was determined. 3+ The concentration of the sample was used to calculate the extraction rate (E) according to formula (1). The extraction results are shown in Table 7. (2) A 0.3 mol / L aminophosphonic acid (P,P'-[(octylamine)di(methylene)]di[p-cyclohexylphosphonic acid]) for extracting iron from wet-process phosphoric acid was prepared using S-260 solvent oil diluent and 10% n-octanol (phase modifier) ​​as the organic phase. The organic phase and wet-process phosphoric acid solution (aqueous phase) were mixed at a volume ratio of 5:1 for extraction. The extraction time was 30 min and the extraction temperature was 25℃. After extraction, the mixed solution was separated to obtain an organic phase loaded with iron and aluminum ions and a raffinate. The Fe content in the raffinate was determined. 3+ The concentration of the sample was used to calculate the extraction rate (E) according to formula (1). The extraction results are shown in Table 7. Table 7 Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the spirit and scope of the technical solutions of this application, and all such modifications or substitutions should be covered within the scope of the claims of this application.

Claims

1. An amino-based diphosphonic acid, characterized in that, The structural formula of the amino-diphosphonic acid is: or In the formula, R1 is cyclohexyl or phenyl or 9-octadecenyl or a straight-chain alkyl group having 6 to 20 carbon atoms, and R2 and / or R4 are straight-chain alkyl groups having 6 to 12 carbon atoms.

2. The method for preparing an amino-based diphosphonic acid as described in claim 1, characterized in that, The steps are as follows: (1) Mix the solvent, primary amine, cyclohexylphosphonic acid and inorganic acid, and heat until the solution is clear and transparent; (2) Add formaldehyde solution or paraformaldehyde to the clear and transparent solution to carry out the reaction; (3) Remove the aqueous phase from the mixture after the reaction in step (2), dissolve the gelatinous substance after removing the aqueous phase with dichloromethane, and obtain amino-based phosphonic acid by washing, rotary evaporation and drying; The reaction equation for the preparation of amino-based phosphonic acid is as follows: 。 3. The method for preparing an amino-based diphosphonic acid as described in claim 2, characterized in that, The solvent mentioned in step (1) is one or more of water, methanol, ethanol, propanol, and isopropanol; the primary amine is one or more of cyclohexylamine, aniline, oleylamine, straight-chain primary amines with 6 to 20 carbon atoms, and primary amine N1923; the inorganic acid is one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, or acetic acid.

4. The method for preparing an amino-based diphosphonic acid as described in claim 2, characterized in that, The molar ratio of the primary amine to cyclohexylphosphonic acid can be 1:1 to 1:5; the molar ratio of the primary amine to the inorganic acid can be 10:1 to 1:5; the mass ratio of water to the primary amine can be 3:1 to 15:1; and the molar ratio of the primary amine to the formaldehyde solution is 1:1 to 1:

5.

5. The method for preparing an amino-based diphosphonic acid as described in claim 2, characterized in that, The heating temperature in step (1) is 50~110℃. o C; The reaction temperature in step (2) is 50~100℃ o C, the reaction time is 1~12h.

6. The application of the amino-diphosphonic acid prepared according to any one of claims 1-5 in the extraction of iron from wet phosphoric acid solution.

7. The application of the aminophosphonic acid as described in claim 6 in the extraction of iron from wet phosphoric acid solution, characterized in that, Fe in the wet phosphoric acid solution 3+ The concentrations are 0.1~6.5 g / L, sulfuric acid concentrations are 0.01~5 mol / L, and phosphoric acid concentrations are 0.5~8 mol / L.

8. The application of the amino-diphosphonic acid as described in claim 7 in the extraction of iron from wet phosphoric acid solution, characterized in that, The extraction steps are as follows: (1) Use amino-diphosphonic acid prepared with diluent and phase conditioning agent as organic phase, and the concentration of amino-diphosphonic acid in organic phase is 0.01~1mol / L; (2) Preheat organic phase and wet phosphoric acid solution separately, mix and stir for extraction, and separate the extracted mixed solution to obtain iron-loaded organic phase and raffinate; (3) Back-extract the iron-loaded organic phase with back-extracting agent at a temperature of 15~80°C. o C, yields an aqueous solution containing iron ions.

9. The method for preparing an amino-based diphosphonic acid as described in claim 8, characterized in that, The diluent and phase modifier mentioned in step (1) are one or more of aliphatic hydrocarbons, halogenated hydrocarbons, aromatic hydrocarbons, solvent oils, and alcohols; the volume ratio of wet phosphoric acid solution to organic phase mentioned in step (2) is 1:5 to 5:1, the extraction time is 1 to 120 min, and the extraction temperature is 10 to 90 °C. o C; In step (3), the stripping agent is 0.1~1 mol / L ammonium oxalate, and the stripping time is 10~120 min.

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