A quaternary ammonium salt cationic collector containing an azobenzene group, and a preparation method and application thereof
By synthesizing a quaternary ammonium salt cationic collector containing azophenyl groups and utilizing photoresponsiveness to adjust the foam state, the problems of poor selectivity and excessive foam stability in existing cationic collectors have been solved, achieving efficient recovery of medium- and low-grade phosphate rock.
Patent Information
- Application Number
- CN202311062528.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-23
- Publication Date
- 2026-08-25
- Estimated Expiration
- 2043-08-23
AI Technical Summary
In existing phosphate ore beneficiation processes, cationic collectors have weak collecting ability and poor selectivity for complex mineral systems, and the overly stable flotation foam affects the smoothness of the process, making it difficult to effectively recover low- and medium-grade siliceous calcium phosphate ore.
A quaternary ammonium salt cationic collector containing an azophenyl group was synthesized. By utilizing the changes in molecular structure under ultraviolet and visible light, the adsorption density of the agent on silicate minerals was adjusted to achieve foam control.
It improves the selectivity and flotation efficiency of phosphate rock, simplifies the defoaming process, conforms to the concept of green mineral processing, and increases the recovery rate of medium and low grade phosphate rock.
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Figure CN117206084B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of phosphate rock collectors, and more particularly to a quaternary ammonium salt cationic collector containing an azophenyl group, its preparation method, and its application. Background Technology
[0002] my country possesses a large amount of phosphate rock resources, but these are mainly low- to medium-grade phosphate rock, with an average grade of only 17%. Of the proven reserves, approximately 85% are difficult-to-separate and difficult-to-process sedimentary phosphate rocks, most of which are low- to medium-grade siliceous-calcareous (colloidal) phosphate rock that is difficult to separate. In recent years, with the continuous development and consumption of large quantities of high-grade rich phosphate ores and easily processed phosphate ores, the scarcity of domestic phosphate rock resources has gradually become more prominent, and even increasingly serious. Therefore, it is imperative to accelerate the resolution of key technical challenges in the recovery and utilization of low- to medium-grade phosphate rock resources in a "lean, fine, and complex" state.
[0003] The recovery of low- and medium-grade silica-calcium phosphate rock currently faces numerous challenges, including a limited variety of highly efficient and selective reagents, insufficient research on flotation mechanisms, unsatisfactory froth performance, and difficulties in applying novel reagents. These issues urgently require solutions. Currently, commonly used cationic collectors in phosphate ore beneficiation exhibit weak collecting ability in complex mineral systems and poor selectivity for target minerals. Furthermore, in actual flotation processes, the product froth becomes overly stable, severely impacting process smoothness. This invention focuses on the problem of flotation froth control, synthesizing a highly efficient cationic desilication collector with azophenyl groups. By utilizing changes in its molecular structure under ultraviolet and visible light irradiation, the adsorption density of the reagent on silicate minerals can be adjusted, thereby realizing the design concept of artificially green and environmentally friendly froth control. This addresses the problems of sticky froth, difficulty in defoaming, and limitations on industrial application. Summary of the Invention
[0004] Technical problem to be solved: In view of the shortcomings of the current reverse flotation production process of phosphate rock in the existing technology, the present invention provides a quaternary ammonium salt cationic collector containing azophenyl groups, its preparation method and application, which has good selectivity and flotation efficiency.
[0005] Technical solution: A quaternary ammonium salt cationic collector containing an azophenyl group, the chemical structural formula of which is as follows: , Where R1 is -(CH2) n - where n is an integer between 3 and 6.
[0006] The preparation method of the quaternary ammonium salt cationic collector containing an azophenyl group described above is as follows: Step 1, Preparation of intermediates: 4-Hydroxy-4'-methoxyazobenzene was dissolved in acetone at a temperature of 20-50°C. Dibromoalkanes were added dropwise. After the addition was complete, the mixture was stirred at 50-55°C for 22-28 hours. After the reaction was completed, the acetone in the reaction system was removed by rotary evaporation. The remaining solid precipitate was recrystallized twice with anhydrous ethanol to obtain the intermediate product 4-hydroxy-4'-bromoalkoxyazobenzene. The dibromoalkanes were dibromopropane, dibromobutane, dibromopentane, or dibromohexane. The molar ratio of 4-hydroxy-4'-methoxyazobenzene to dibromoalkanes was 1:(1.2-2.2), and the molar ratio of 4-hydroxy-4'-methoxyazobenzene to acetone was 1:(45-55). Step 2, Preparation of quaternary ammonium salt cationic collectors containing azophenyl groups: The 4-hydroxy-4'-bromoalkoxyazobenzene prepared in step one is dissolved in ethanol, and the temperature is controlled at 30-35℃. A 30-35% (w / w) solution of trimethylamine in ethanol is added dropwise. After the addition is complete, the mixture is stirred at 70-75℃ for 22-28 hours to obtain a quaternary ammonium salt cationic collector containing an azophenyl group. The molar ratio of 4-hydroxy-4'-bromoalkoxyazobenzene to ethanol is 1:(45-55), and the molar ratio of trimethylamine in the trimethylamine ethanol solution to 4-hydroxy-4'-methoxyazobenzene in step one is (1.2-2.2):1.
[0007] The molar ratio of 4-hydroxy-4'-methoxyazobenzene in step one, dibromoalkane in step one, and trimethylamine in the trimethylamine ethanol solution in step two is 1:1.5:1.5.
[0008] The dibromoalkane in step one described above is 1,3-dibromopropane or 1,6-dibromohexane.
[0009] In step one described above, the temperature is controlled at 45°C, dibromoalkane is added dropwise, and after the addition is complete, the mixture is stirred at 53°C for 24 hours.
[0010] In step two described above, the temperature is controlled at 32°C, and a trimethylamine ethanol solution is added dropwise.
[0011] The application of the aforementioned quaternary ammonium salt cationic collector containing azophenyl groups in the reverse flotation desilication of phosphate rock.
[0012] The aforementioned quaternary ammonium salt cationic collector containing azophenyl groups can be used after being dissolved in water at room temperature by stirring. The weight ratio of the collector to water during preparation is 1:(100-200).
[0013] This invention provides a photoresponsive quaternary ammonium salt cationic collector containing an azophenyl group through simple chemical synthesis. This collector, via its head amino group, specifically adsorbs onto active sites on the surface of silicate minerals, thereby increasing the removal rate of siliceous gangue from phosphate rock and further improving the phosphate rock grade. Compared to traditional methods using physical stirring and defoaming agents, this method directly utilizes the adsorption properties of the collector and employs simpler and cleaner ultraviolet light conditions for defoaming. It also allows for more convenient artificial adjustment of the foam state and aligns better with the principles of green mineral processing.
[0014] Beneficial Effects: The quaternary ammonium salt cationic collector containing an azophenyl group provided by this invention, its preparation method, and its application have the following beneficial effects: 1. The quaternary ammonium salt cationic collector containing azophenyl groups of the present invention can be directly used in the reverse flotation desilication application of phosphate rock. It can be used after being dissolved by stirring with water at room temperature. 2. The quaternary ammonium salt cationic collector containing azophenyl groups of the present invention has good water solubility, certain foaming ability, simple synthesis process, and produces different foaming effects under ultraviolet light and visible light, which has certain practical significance for foam control in phosphate rock reverse flotation. Attached Figure Description
[0015] Figure 1 The above are the 1H NMR spectra of the azophenyl-containing quaternary ammonium salt cationic collector of Example 1 under different light conditions.
[0016] Figure 2 The image shows the UV absorption spectra of the azophenyl-containing quaternary ammonium salt cationic collector of Example 1 under different light conditions.
[0017] Figure 3 The process flow diagram is shown for the reverse flotation desilication flotation test of phosphate rock using the azophenyl-containing quaternary ammonium salt cationic collector of Example 3. Implementation
[0018] The present invention will be specifically described below through embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above-described invention are still within the scope of protection of the present invention.
[0019] The materials and reagents used in Examples 1 and 2 are shown in Table 1 below.
[0020] Table 1 Example 1
[0021] This embodiment provides a quaternary ammonium salt cationic collector containing an azophenyl group, with the following chemical structural formula: .
[0022] The preparation method of this quaternary ammonium salt cationic collector containing an azophenyl group is as follows: Step 1, Preparation of intermediates: 4-Hydroxy-4'-methoxyazobenzene was dissolved in acetone at a controlled temperature of 23°C. Dibromopropane was added dropwise in batches over 1 hour. After the addition was complete, the mixture was stirred at 53°C for 24 hours. After the reaction was completed, the acetone in the reaction system was removed by rotary evaporation. The remaining solid precipitate was recrystallized twice with anhydrous ethanol to obtain the intermediate product 4-hydroxy-4'-bromoalkoxyazobenzene. The molar ratio of 4-hydroxy-4'-methoxyazobenzene to dibromopropane was 1:1.5, and the molar ratio of 4-hydroxy-4'-methoxyazobenzene to acetone was 1:50. Step 2, Preparation of quaternary ammonium salt cationic collectors containing azophenyl groups: The 4-hydroxy-4'-bromoalkoxyazobenzene prepared in step one was dissolved in ethanol, and the temperature was controlled at 33°C. A 33% (w / w) trimethylamine ethanol solution was added dropwise. After the addition was complete, the mixture was stirred at 70°C for 24 hours to obtain a quaternary ammonium salt cationic collector containing an azophenyl group. The molar ratio of 4-hydroxy-4'-bromoalkoxyazobenzene to ethanol was 1:50, and the molar ratio of trimethylamine to 4-hydroxy-4'-methoxyazobenzene in the trimethylamine ethanol solution was 1.5:1.
[0023] The 1H NMR spectrum of the azophenyl-group quaternary ammonium salt cationic collector prepared in Example 1 is shown below. Figure 1 As shown, the NMR data includes: Ultraviolet light: 1 H NMR (600 MHz, Deuterium Oxide), δ(ppm): 6.92 (4H,Ar-H), 6.83 (4H, Ar-H), 4.06 (2H, CH2), 3.72 (3H, CH3), 3.45 (2H, CH2), 3.06(9H,CH3), 2.19 (2H, CH2). Natural light: 1¹H NMR (600 MHz, Deuterium Oxide), δ (ppm): 7.72 (4H, Ar-H), 7.06 (4H, Ar-H), 4.17 (2H, CH₂), 3.83 (3H, CH₃), 3.49 (2H, CH₂), 3.09 (9H, CH₃), 2.25 (2H, CH₂). The obvious chemical shift differences in the figure indicate that the collector molecule was successfully synthesized and possesses photoisomerism.
[0024] The UV absorption spectra of the azophenyl-group quaternary ammonium salt cationic collector prepared in Example 1 under different light conditions are shown below. Figure 2 As shown, under both natural light and ultraviolet light conditions, the absorbance of the collector molecules at different wavelengths varies significantly, indicating that the collector molecules undergo isomerization under ultraviolet light stimulation. Example 2
[0025] This embodiment provides a quaternary ammonium salt cationic collector containing an azophenyl group, with the following chemical structural formula: .
[0026] The preparation method of this quaternary ammonium salt cationic collector containing an azophenyl group is as follows: Step 1, Preparation of intermediates: 4-Hydroxy-4'-methoxyazobenzene was dissolved in acetone at 25°C. 1,6-Dibromohexane was added dropwise in batches over 1 hour. After the addition was complete, the mixture was stirred at 55°C for 24 hours. After the reaction was complete, the acetone in the reaction system was removed by rotary evaporation. The remaining solid precipitate was recrystallized twice with anhydrous ethanol to obtain the intermediate product 4-hydroxy-4'-bromoalkoxyazobenzene. The molar ratio of 4-hydroxy-4'-methoxyazobenzene to 1,6-dibromohexane was 1:1.8, and the molar ratio of 4-hydroxy-4'-methoxyazobenzene to acetone was 1:55. Step 2, Preparation of quaternary ammonium salt cationic collectors containing azophenyl groups: The 4-hydroxy-4'-bromoalkoxyazobenzene prepared in step one was dissolved in ethanol, and the temperature was controlled at 35°C. A 33% (w / w) trimethylamine ethanol solution was added dropwise. After the addition was complete, the mixture was stirred at 73°C for 24 hours to obtain a quaternary ammonium salt cationic collector containing an azophenyl group. The molar ratio of 4-hydroxy-4'-bromoalkoxyazobenzene to ethanol was 1:55, and the molar ratio of trimethylamine to 4-hydroxy-4'-methoxyazobenzene in the trimethylamine ethanol solution was 1.8:1. Example 3
[0027] This embodiment provides a quaternary ammonium salt cationic collector containing an azophenyl group, with the following chemical structural formula: .
[0028] The preparation method of this quaternary ammonium salt cationic collector containing an azophenyl group is as follows: Step 1, Preparation of intermediates: 4-Hydroxy-4'-methoxyazobenzene was dissolved in acetone at 23°C. Dibromopropane was added dropwise in batches over 1 hour. After the addition was complete, the mixture was stirred at 53°C for 24 hours. After the reaction was completed, the acetone in the reaction system was removed by rotary evaporation. The remaining solid precipitate was recrystallized twice with anhydrous ethanol to obtain the intermediate product 4-hydroxy-4'-bromoalkoxyazobenzene. The molar ratio of 4-hydroxy-4'-methoxyazobenzene to dibromopropane was 1:1.8, and the molar ratio of 4-hydroxy-4'-methoxyazobenzene to acetone was 1:50. Step 2, Preparation of quaternary ammonium salt cationic collectors containing azophenyl groups: The 4-hydroxy-4'-bromoalkoxyazobenzene prepared in step one was dissolved in ethanol, and the temperature was controlled at 33°C. A 33% (w / w) trimethylamine ethanol solution was added dropwise. After the addition was complete, the mixture was stirred at 70°C for 24 hours to obtain a quaternary ammonium salt cationic collector containing an azophenyl group. The molar ratio of 4-hydroxy-4'-bromoalkoxyazobenzene to ethanol was 1:50, and the molar ratio of trimethylamine to 4-hydroxy-4'-methoxyazobenzene in the trimethylamine ethanol solution was 1.8:1.
[0029] The quaternary ammonium salt cationic collector containing azophenyl groups prepared in Example 3 was used in a reverse flotation desilication flotation test of phosphate rock. The mineral raw material used was a siliceous calcium phosphate rock from Guizhou Province. The ore sample contained 17.25% P2O5, 7.78% MgO, and 18.16% SiO2, with gangue minerals mainly consisting of quartz and dolomite.
[0030] The flotation reagent system and operating methods are as follows: Figure 3As shown, the specific process is as follows: 150g of raw ore sample was weighed and ground for 14 minutes at a pulp concentration of 66% to allow for basic individual dissociation of the components. The sample then entered the flotation process. Phosphoric acid and sulfuric acid were mixed in a specific ratio to adjust the pH of the raw ore pulp to 4. A fatty acid collector was used for reverse flotation to remove magnesium. When the magnesium content of the removed magnesium concentrate reached approximately 1%, reverse flotation desilication was performed. A three-stage reverse flotation desilication process was adopted. Sodium carbonate was used to adjust the pH of the removed magnesium concentrate pulp to 8. The aforementioned synthetic reagents were used for reverse flotation desilication, with dosages of 0.4kg / t, 0.6kg / t, and 0.2kg / t for the three stages, respectively. After enrichment, the desilication tailings were treated with ultraviolet light and then scavenged for 2 minutes after merging. The flotation temperature was controlled at ambient temperature (20-25℃). The flotation test results are shown in Table 2 below.
[0031] Table 2
[0032] Through experimental process, it was found that the foam in the desilication process can break down quickly after being exposed to ultraviolet light. The flotation foam layer is significantly thinner than before the light exposure, the overall flotation process can proceed smoothly, and the final phosphate concentrate can be obtained with a P2O5 grade of 32.94%, a recovery rate of 53.83%, a SiO2 grade of 8.55%, and a MgO grade of less than 1.5%.
[0033] The embodiments of the present invention have been described in detail above. For those skilled in the art, there may be changes in the specific implementation methods and application scope based on the ideas of the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.
Claims
1. A quaternary ammonium salt cationic collector containing an azophenyl group, characterized in that... The chemical structural formula of the quaternary ammonium salt cationic collector containing an azophenyl group is: ， Where R1 is -(CH2) n - where n is an integer between 3 and 6; The preparation method of this quaternary ammonium salt cationic collector containing an azophenyl group is as follows: Step 1, Preparation of intermediates: 4-Hydroxy-4'-methoxyazobenzene was dissolved in acetone at a temperature of 20-50°C. Dibromoalkanes were added dropwise. After the addition was complete, the mixture was stirred at 50-55°C for 24 hours. After the reaction was completed, the acetone in the reaction system was removed by rotary evaporation. The remaining solid precipitate was recrystallized twice with anhydrous ethanol to obtain the intermediate product 4-hydroxy-4'-bromoalkoxyazobenzene. The dibromoalkanes were dibromopropane, dibromobutane, dibromopentane, or dibromohexane. The molar ratio of 4-hydroxy-4'-methoxyazobenzene to dibromoalkanes was 1:(1.2-2.2), and the molar ratio of 4-hydroxy-4'-methoxyazobenzene to acetone was 1:(45-55). Step 2, Preparation of quaternary ammonium salt cationic collectors containing azophenyl groups: The 4-hydroxy-4'-bromoalkoxyazobenzene prepared in step one is dissolved in ethanol, and the temperature is controlled at 30-35℃. A 30-35% (w / w) trimethylamine ethanol solution is added dropwise. After the addition is complete, the mixture is stirred at 70-75℃ for 24 hours to obtain a quaternary ammonium salt cationic collector containing an azophenyl group. The molar ratio of 4-hydroxy-4'-bromoalkoxyazobenzene to ethanol is 1:(45-55), and the molar ratio of trimethylamine to 4-hydroxy-4'-methoxyazobenzene in the trimethylamine ethanol solution is (1.2-2.2):
1. The azophenyl-containing quaternary ammonium salt cationic collector is used for reverse flotation desilication of phosphate rock. The azophenyl-containing quaternary ammonium salt cationic collector can be used after being dissolved in water at room temperature by stirring. The weight ratio of collector to water is 1:(100-200) when preparing the mixture.
2. The quaternary ammonium salt cationic collector containing an azophenyl group according to claim 1, characterized in that: The dibromoalkane in step one is 1,3-dibromopropane or 1,6-dibromohexane.
3. The quaternary ammonium salt cationic collector containing an azophenyl group according to claim 1, characterized in that: In step one, the temperature is controlled at 23°C, and dibromoalkane is added dropwise. After the addition is complete, the mixture is stirred at 53°C for 24 hours.
4. The quaternary ammonium salt cationic collector containing an azophenyl group according to claim 1, characterized in that: In step two, the temperature is controlled at 33°C, and an ethanol solution of trimethylamine is added dropwise.