High concentration wet-process phosphoric acid impurity removal method based on oleylamine dispersant

Abstract

The application discloses a high-concentration wet-process phosphoric acid impurity removal method based on an oleylamine dispersant, and is characterized in that oleylamine is used as a dispersant, and a precipitate is generated in a wet-process phosphoric acid system under the synergistic action of a premixed precipitant, and the purified wet-process phosphoric acid is obtained after filtration. By introducing oleylamine as a dispersant, the dispersion state of NaMgAlF6 precipitate is regulated, efficient impurity removal and high-yield recovery of phosphorus resources are realized, and the method is suitable for industrialized continuous production.

Description

Technical Field

[0001] This invention relates to a wet phosphoric acid purification method, and more particularly to a high-concentration wet phosphoric acid purification method based on oleylamine dispersant. Background Technology

[0002] Wet-process phosphoric acid is a core raw material in the phosphorus chemical industry and is widely used in fertilizers, food, and pharmaceuticals. Currently, industrially, wet-process phosphoric acid is mostly produced from phosphate rock using a hemihydrate or dihydrate process. However, due to the complex composition of phosphate rock, the resulting wet-process phosphoric acid often contains a large number of impurities, including Mg. 2+ Al 3+ Metal ions are key impurities that affect the quality of phosphoric acid and its subsequent applications, and must be removed through purification treatment.

[0003] In existing wet phosphoric acid purification technologies, HF and Na2SO4 are used as precipitants to remove Mg by generating NaMgAlF6 coprecipitate. 2+ Al 3+ This method, due to its high impurity removal efficiency and strong process adaptability, has become one of the mainstream research directions. However, this technology has significant technical drawbacks when treating wet-process phosphoric acid with high P2O5 concentration and high metal impurity concentration (≥39wt%): 1. Direct solid-liquid separation of pure NaMgAlF6 precipitate system is difficult: The complex system formed by high concentration of P2O5 and high metal ions will cause the NaMgAlF6 precipitate to be in colloidal form with small particles and high system viscosity. When directly filtration is performed, the filter pores are easily blocked, and the P2O5 yield can only reach 20%-30%, which is difficult to meet the needs of industrial production.

[0004] 2. Dilution process incurs additional costs: To improve separation performance, existing technologies often use wet phosphoric acid dilution to reduce system viscosity. However, dilution requires an additional concentration process, which not only consumes a lot of energy but may also cause phosphorus resource depletion, violating the development concept of efficient resource utilization.

[0005] 3. Poor compatibility of existing dispersants: Some existing technologies attempt to introduce dispersants to improve precipitation dispersion, but most of them use amine dispersants such as oleic acid and octylamine. These dispersants are expensive and are prone to over-dispersion in high-concentration phosphoric acid systems, causing ultrafine particles to pass through the filter paper, which in turn reduces the yield of P2O5. Conventional alcohol dispersants (such as oleyl alcohol) have problems with insufficient dispersion ability and limited improvement in impurity removal effect.

[0006] 4. Long flocculation and sedimentation cycle: Existing technologies use polymeric flocculants (such as CMC) to enhance sedimentation and sedimentation, which can improve the yield of P2O5, but the sedimentation cycle is as long as 2 days, which cannot match the pace of continuous industrial production.

[0007] Therefore, developing a wet phosphoric acid purification method that is suitable for high P2O5 concentration and high metal impurity concentration, can effectively improve precipitation dispersion, increase impurity removal efficiency and P2O5 yield, and is cost-effective and simple, has become a technical problem that urgently needs to be solved in the current field of wet phosphoric acid purification.

[0008] The purpose of this invention is to provide a high-concentration wet phosphoric acid purification method based on oleylamine dispersant. This invention introduces oleylamine as a dispersant to regulate the dispersion state of NaMgAlF6 precipitate, achieving efficient impurity removal and high-yield recovery of phosphorus resources, making it suitable for continuous industrial production.

[0009] A high-concentration wet phosphoric acid purification method based on oleylamine dispersant involves using oleylamine as a dispersant, which, in synergistic action with a premixed precipitant, generates a precipitate in the wet phosphoric acid system. After filtration, purified wet phosphoric acid is obtained.

[0010] Preferably, the aforementioned high-concentration wet phosphoric acid purification method based on oleylamine dispersant includes the following steps: (1) Raw material preparation: Take wet-process phosphoric acid and test the content of magnesium and aluminum in it; (2) Addition of dispersant: Add oleylamine dispersant to the wet-process phosphoric acid and stir to disperse; (3) Precipitation reaction: Add a premixed precipitant consisting of Na2SO4 solution and HF solution to the dispersion system in step (2), and react under the same stirring conditions as in step (2) to generate a precipitate; (4) Solid-liquid separation: The reaction system of step (3) is filtered to obtain purified wet phosphoric acid.

[0011] Preferably, in the aforementioned high-concentration wet phosphoric acid purification method based on oleylamine dispersant, the wet phosphoric acid contains P2O5 content ≥39wt%, MgO content ≥2.23wt%, Al2O3 content ≥2.33wt%, and the pH of the wet phosphoric acid is -0.47 to -0.40.

[0012] Preferably, in the aforementioned high-concentration wet phosphoric acid purification method based on oleylamine dispersant, in step (2), the amount of oleylamine added is 1.2-2.0 wt% of the wet phosphoric acid.

[0013] Preferably, in the aforementioned high-concentration wet phosphoric acid purification method based on oleylamine dispersant, in step (2), the stirring is carried out at 50-70°C, with a rotation speed of 150-250 r / min and a time of 10-30 min.

[0014] Preferably, in the aforementioned high-concentration wet phosphoric acid purification method based on oleylamine dispersant, the stirring is carried out at 60°C, at a rotation speed of 200 r / min, for 20 min.

[0015] Preferably, in the aforementioned high-concentration wet phosphoric acid purification method based on oleylamine dispersant, in step (3), the premixed precipitant is composed of a 20% Na2SO4 solution and a 40% HF solution by mass fraction.

[0016] Preferably, in the aforementioned high-concentration wet phosphoric acid purification method based on oleylamine dispersant, in step (3), the mixing molar ratio of the premixed precipitant to the wet phosphoric acid is F:Na:Mg:Al=5-7:0.9-1.1:1.1-1.3:1; and the stirring reaction time is 20-40 min.

[0017] Preferably, in the aforementioned high-concentration wet phosphoric acid purification method based on oleylamine dispersant, the mixing molar ratio of the premixed precipitant to wet phosphoric acid is F:Na:Mg:Al = 6:1:1.23:1, and the reaction time is 30 min.

[0018] Preferably, in the aforementioned high-concentration wet phosphoric acid purification method based on oleylamine dispersant, the filtration is vacuum filtration with a vacuum degree of 0.08-0.10 MPa.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention uses oleylamine as a dispersant, which can be directly applied to high-concentration wet-process phosphoric acid systems with P2O5 content higher than 39wt%, MgO content higher than 2.23wt%, and Al2O3 content higher than 2.33wt%, without the need for dilution, thus avoiding the extra energy consumption and phosphorus resource loss of concentration after dilution, and significantly reducing the cost of industrial production.

[0020] (2) Amine dispersants, due to their hydrophilic amino groups and lipophilic long chains, can form a directional adsorption film on the surface of precipitated particles, regulate surface charge, enhance electrostatic repulsion, and construct steric hindrance. While depolymerizing and dispersing, they also promote the complexation and precipitation of unreacted ions, significantly improving the removal rate. Under optimal process conditions, Mg... 2+ The removal rate can reach over 88.92%, Al 3+ The removal rate can reach over 97.11%, which is a significant improvement in impurity removal efficiency compared to a pure precipitation system.

[0021] (3) The oleamide dispersant of the present invention can effectively destroy the colloidal aggregate structure of NaMgAlF6 precipitate, avoid filter pore blockage, reduce phosphoric acid entrainment, and increase the P2O5 yield from less than 36.8% in the pure precipitation system to 94.76%, thereby achieving efficient recovery of phosphorus resources.

[0022] (4) The oleamide dispersant of the present invention is inexpensive, readily available, requires only a small amount, does not require complex equipment, and can be completed in the same reaction vessel for stirring, dispersion and precipitation reactions. The process cycle is short and it is suitable for industrial continuous production.

[0023] (5) By introducing an oleylamine dispersant, the present invention only regulates the dispersion state of the NaMgAlF6 precipitate without changing the phase structure of the precipitate. The precipitate can be further recycled and reused, reducing solid waste pollution. Attached Figure Description

[0024] Figure 1 Mg in different dispersion systems in the embodiments of the present invention 2+ Al 3+ Removal rate comparison chart; where CLEAN is the pure precipitation system, A is the oleylamine system, B is the octylamine system, C is the oleyl alcohol system, and D is the oleic acid system; Figure 2 This is a comparison chart of P2O5 yields for different dispersion systems in the embodiments of the present invention; wherein, the vertical axis represents P2O5 yield (%), the horizontal axis represents the type of dispersion system, CLEAN represents pure precipitation system, A represents oleylamine system, B represents octylamine system, C represents oleyl alcohol system, and D represents oleic acid system. Figure 3 This is a comparison chart of the turbidity of the purified liquid from the oleylamine dispersion system and the pure precipitation system (CLEAN) in an embodiment of the present invention; wherein, CLEAN is the pure precipitation system, A is the oleylamine system, B is the octylamine system, C is the oleyl alcohol system, and D is the oleic acid system, and the turbidity unit is NTU; Figure 4 SEM images (500 nm) of precipitates from different dispersion systems are shown; where a represents the CLEAN system, b represents the octylamine system, c represents the oleyl alcohol system, d represents the oleic acid system, and e represents the oleylamine system. Figure 4 As can be seen, the precipitate of the oleylamine system exhibits slight aggregation, and its particle dispersibility is better than that of other systems. Figure 5 This is a comparison of the XRD patterns of the oleylamine dispersion system and the pure precipitate system in this embodiment of the invention; where CLEAN is the pure precipitate system, A is the oleylamine system, B is the octylamine system, C is the oleyl alcohol system, and D is the oleic acid system; both the CLEAN and A curves show a single NaMgAlF6 phase, indicating that oleylamine did not change the precipitate phase; Figure 6 This is an EDS analysis chromatogram of the precipitate from the oleylamine dispersion system in an embodiment of the present invention; wherein, Mg, Al, Na, and F elements were detected, which is consistent with the stoichiometric ratio of NaMgAlF6. Detailed Implementation

[0025] The present invention will be further described below with reference to embodiments, but these embodiments are not intended to limit the scope of the invention.

[0026] Embodiments of the present invention In this embodiment, the raw material used is semi-aqueous wet-process phosphoric acid produced by a chemical company in Guizhou using layer A ore. Its main components are as follows: P2O5 39.6wt%, Fe2O3 0.70wt%, MgO 2.23wt%, Al2O3 2.33wt%, CaO 0.18wt%, NaO 0.02wt%, F 0.67wt%, SO3 1.21wt%. Trace impurities: As 77ppm, Na 236ppm, K 687ppm, Pb 3.4ppm, Cr 143ppm; pH: -0.47. The oleylamine dispersant used was AR grade, purchased from Macklin Corporation; the precipitants were AR grade Na2SO4 solution (20% by mass) and AR grade HF solution (40% by mass); the testing instruments used included a digital display constant temperature water bath (DF-101SH), a centrifuge (H-1850), an electronic analytical balance (JF), an inductively coupled plasma mass spectrometer (ICAP7400), a scanning electron microscope (ZEISS300), an X-ray diffractometer (D8advance), and a turbidimeter (WZB-172), etc.

[0027] Impurity removal performance evaluation method: (1) Mg 2+ Al 3+ The removal rate (E) is calculated according to formula (1): In the formula: C i Mg before impurity removal 2+ Al 3+ Ion concentration (mg / L), Vi is the volume of the solution before purification (L); C f Mg after impurity removal 2+ Al 3+ Ion concentration (mg / L), V f The volume of the solution after impurity removal (L).

[0028] (2) The yield of P2O5 (Y) is calculated according to formula (2): In the formula: W i The content of P2O5 before impurity removal (wt%), m i The mass (g) of the phosphoric acid solution before impurity removal; W f The content of P2O5 after impurity removal (wt%) is m f The mass (g) of the phosphoric acid solution after impurity removal.

[0029] (3) The turbidity of the purified liquid was measured using a turbidity meter (WZB-172), and the unit is NTU. Example 1

[0030] A high-concentration wet phosphoric acid purification method based on oleylamine dispersant includes the following steps: (1) Raw material pretreatment: The above-mentioned high-concentration wet-process phosphoric acid was selected as raw material and prepared for use; (2) Addition of dispersant: Add 1.2g of oleylamine dispersant to 100g of wet-process phosphoric acid and stir and disperse for 10min at 50℃ and 150r / min; (3) Precipitation reaction: Add a premixed precipitant consisting of 20% Na2SO4 solution and 40% HF solution, and control the molar ratio of precipitant F:Na:Mg:Al = 5.0:0.9:1.1:1.0. React for 20 min at 50℃ and 150 r / min. (4) Solid-liquid separation: Under a vacuum of 0.08 MPa, quantitative filter paper was used for vacuum filtration for 2.0 h to obtain purified wet phosphoric acid and NaMgAlF6 precipitate. Example 2

[0031] A high-concentration wet phosphoric acid purification method based on oleylamine dispersant includes the following steps: (1) Raw material pretreatment: The above-mentioned high-concentration wet-process phosphoric acid was selected as raw material and prepared for use; (2) Addition of dispersant: Add 1.6g of oleylamine dispersant to 100g of wet-process phosphoric acid and stir and disperse for 20min at 60℃ and 200r / min; (3) Precipitation reaction: Add a premixed precipitant consisting of 20% Na2SO4 solution and 40% HF solution, and control the molar ratio of precipitant F:Na:Mg:Al = 6.0:1.0:1.23:1.0. React at 60℃ and 200r / min for 30min. (4) Solid-liquid separation: Under a vacuum of 0.09 MPa, quantitative filter paper was used for vacuum filtration for 2.5 h to obtain purified wet phosphoric acid and NaMgAlF6 precipitate. Example 3

[0032] A high-concentration wet phosphoric acid purification method based on oleylamine dispersant includes the following steps: (1) Raw material pretreatment: The above-mentioned high-concentration wet-process phosphoric acid was selected as raw material and prepared for use; (2) Addition of dispersant: Add 2.0g of oleylamine dispersant to 100g of wet-process phosphoric acid and stir and disperse for 30min at 70℃ and 250r / min; (3) Precipitation reaction: Add a premixed precipitant consisting of 20% Na2SO4 solution and 40% HF solution, and control the molar ratio of precipitant F:Na:Mg:Al = 7.0:1.1:1.3:1.0. React at 70℃ and 250r / min for 40min. (4) Solid-liquid separation: Under a vacuum of 0.10 MPa, quantitative filter paper was used for vacuum filtration for 3.0 h to obtain purified wet phosphoric acid and NaMgAlF6 precipitate. Example 4

[0033] A high-concentration wet phosphoric acid purification method based on oleylamine dispersant is different from Example 2 in that the amount of oleylamine added in step (2) is 1.4g, while the remaining steps and parameters are the same as in Example 2. Example 5

[0034] A high-concentration wet phosphoric acid purification method based on oleylamine dispersant differs from Example 2 in that the molar ratio of precipitant in step (3) is F:Na:Mg:Al=5.5:1.0:1.2:1.0, while the remaining steps and parameters are the same as in Example 2.

[0035] Comparative test To verify the beneficial effects of the present invention, a comparative experiment was conducted using a pure precipitation system (without dispersant, CLEAN system), an octylamine dispersant system, an oleyl alcohol dispersant system, and an oleic acid dispersant system. The remaining process parameters were the same as in Example 2. The test results are shown in the accompanying drawings of the specification.

[0036] The comparative results show that, by using oleylamine as a dispersant, the present invention increases the P2O5 yield from 36.8% in the CLEAN system to 94.76% without significantly affecting the impurity removal efficiency. Although the turbidity of the purified liquid is slightly higher than that of other systems, it effectively solves the core defects of the pure precipitation system, such as the difficulty of solid-liquid separation and the low P2O5 yield.

[0037] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-concentration wet phosphoric acid purification method based on oleylamine dispersant, characterized in that: Using oleylamine as a dispersant, in synergistic effect with a premixed precipitant, a precipitate is generated in the wet-process phosphoric acid system, and purified wet-process phosphoric acid is obtained after filtration.

2. The high-concentration wet phosphoric acid purification method based on oleylamine dispersant according to claim 1, characterized in that, Includes the following steps: (1) Raw material preparation: Take wet-process phosphoric acid and test the content of magnesium and aluminum in it; (2) Addition of dispersant: Add oleylamine dispersant to the wet-process phosphoric acid and stir to disperse; (3) Precipitation reaction: Add a premixed precipitant consisting of Na2SO4 solution and HF solution to the dispersion system in step (2), and react under the same stirring conditions as in step (2) to generate a precipitate; (4) Solid-liquid separation: The reaction system of step (3) is filtered to obtain purified wet phosphoric acid.

3. The high-concentration wet phosphoric acid purification method based on oleylamine dispersant according to claim 1 or 2, characterized in that: The wet-process phosphoric acid has a P2O5 content ≥39wt%, an MgO content ≥2.23wt%, an Al2O3 content ≥2.33wt%, and a pH of -0.47 to -0.

40.

4. The high-concentration wet phosphoric acid purification method based on oleylamine dispersant according to claim 2, characterized in that: In step (2), the amount of oleylamine added is 1.2-2.0 wt% of wet-process phosphoric acid.

5. The high-concentration wet phosphoric acid purification method based on oleylamine dispersant according to claim 2, characterized in that: In step (2), the stirring is carried out at 50-70℃, with a rotation speed of 150-250r / min and a time of 10-30min.

6. The high-concentration wet phosphoric acid purification method based on oleylamine dispersant according to claim 5, characterized in that: The stirring was carried out at 60°C, at a speed of 200 r / min, for 20 min.

7. The high-concentration wet phosphoric acid purification method based on oleylamine dispersant according to claim 2, characterized in that: In step (3), the premixed precipitant is composed of a 20% Na2SO4 solution and a 40% HF solution by mass.

8. The high-concentration wet phosphoric acid purification method based on oleylamine dispersant according to claim 2, characterized in that: In step (3), the mixing molar ratio of the premixed precipitant to wet phosphoric acid is F:Na:Mg:Al = 5-7:0.9-1.1:1.1-1.3:1; the stirring reaction time is 20-40 min.

9. The high-concentration wet phosphoric acid purification method based on oleylamine dispersant according to claim 8, characterized in that: The molar ratio of the premixed precipitant to wet-process phosphoric acid is F:Na:Mg:Al = 6:1:1.23:1, and the reaction time is 30 min.

10. The high-concentration wet phosphoric acid purification method based on oleylamine dispersant according to claim 1 or 2, characterized in that: The filtration is performed by vacuum filtration, with a vacuum level of 0.08-0.10 MPa.

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