Extracting agent for wet-process phosphoric acid refining and use method thereof

Abstract

The invention discloses an extracting agent for wet-process phosphoric acid refining and a use method thereof. The extracting agent comprises ketone, alcohol, ether, ester, a catalyst and a demulsifier. The mass ratio of the ketone to the alcohol to the ether to the ester to the catalyst to the demulsifier is (70-80): (10-20): (1-5): (1-5): (0.5-1): (0.5-1); the use method comprises the following steps: 1, carrying out countercurrent contact extraction on the extraction agent and raw acid to obtain a loaded organic phase; 2, carrying out countercurrent contact washing on the loaded organic phase to obtain a washed organic phase; 3, carrying out contact back extraction on the washed organic phase to obtain a back extraction solution and a regenerated organic phase; 4, refining the strip liquor to obtain refined phosphoric acid; and meanwhile, the regenerated organic phase is recycled to obtain the extractant which can be recycled. Therefore, the extraction rate of phosphoric acid is high.

Description

TECHNICAL FIELD

[0001] The present application relates to an extractant and its use method, belonging to the field of wet-process phosphoric acid refining, in particular to an extractant for wet-process phosphoric acid refining and its use method. BACKGROUND

[0002] Wet-process phosphoric acid is the main raw material for preparing high-purity phosphoric acid products such as industrial-grade, food-grade and electronic-grade, but due to the low grade of phosphate rock and the complex composition of impurities in China, the produced crude phosphoric acid must be refined to meet the requirements of high-end applications. At present, the refining of wet-process phosphoric acid generally adopts solvent extraction method, that is, using an extractant to selectively transfer phosphoric acid from the aqueous phase to the organic phase to achieve purification; however, due to the limited distribution coefficient of such traditional extractants, and the mass transfer process is easily inhibited by the interface impurity barrier layer, resulting in a large amount of phosphoric acid remaining in the raffinate phase, thus causing the extraction rate of phosphoric acid to be low.

[0003] Chinese patent application No. 200510021984.2, filed on October 31, 2005, discloses an extractive solvent for purifying wet-process phosphoric acid to produce food-grade phosphoric acid and its extraction method. The liquid mixed extractive solvent is mixed by three single extractive solvents in the following volume ratio: tributoxyethyl phosphate: isopropyl ether: cyclohexanol = 1-6: 2-5: 2-4. The method is to mix the liquid mixed extractive solvent with the pretreated wet-process phosphoric acid according to a certain volume ratio, and then shake and separate the layers. After the shaking and separation is completed, the lower layer of raffinate is discharged, and the upper layer of extractive liquid is washed and separated with a small amount of food-grade phosphoric acid. The aqueous phase after separation is subjected to multi-stage extraction with the food-grade phosphoric acid, and then multi-stage back-extraction is carried out with deionized water. The extracted phosphoric acid is concentrated to obtain food-grade phosphoric acid. Although this patent improves the extraction rate of phosphoric acid, it still has the following defects: The distribution coefficient of the designed extractant is limited, which still leads to a low extraction rate of phosphoric acid.

[0004] The information disclosed in this background section is only intended to increase the understanding of the general background of the present patent application and should not be considered as recognition or suggestion that this information forms the prior art that is already known to those of ordinary skill in the art. SUMMARY

[0005] The purpose of the present application is to overcome the defects and problems of low extraction rate of phosphoric acid in the prior art, and to provide an extractant for wet-process phosphoric acid refining with high extraction rate of phosphoric acid and its use method.

[0006] To achieve the above purpose, the technical solution of the present application is: an extractant for wet-process phosphoric acid refining and its use method, the extractant comprising ketone, alcohol, ether, ester, catalyst, demulsifier; The mass ratio of the ketone: alcohol: ether: ester: catalyst: demulsifier is 70-80: 10-20: 1-5: 1-5: 0.5-1: 0.5-1.

[0007] The ketone is any one or any combination of 4-methyl-2-pentanone, 4-methyl-3-penten-2-one, methyl isopropyl ketone, diisopropyl ketone, diisobutyl ketone, and cyclohexanone.

[0008] The ether is any one or any combination of diallyl ether, diisopropyl ether, diisobutyl ether, diethylene glycol diethyl ether, ethyl butyl ether, and dipentyl ether.

[0009] The alcohol is any one or any combination of 2-propanol, cyclopentanol, n-butanol, isobutyl alcohol, n-pentanol, isopentyl alcohol, cyclohexanol, and 2-ethylhexanol.

[0010] The ester is any one or any combination of butyl isobutyrate, methyl isobutyrate, and tributyl phosphate.

[0011] The catalyst is a carboxylic acid and derivatives thereof.

[0012] The carboxylic acid and derivatives thereof are any one or any combination of succinic acid, butenedioic acid, benzoic acid, and ethyl acetate.

[0013] The demulsifier is a zwitterionic polymer.

[0014] The zwitterionic polymer is polysulfobetaine.

[0015] The use method comprises: First step: counter-current contact extraction of the extractant and the original acid to obtain a loaded organic phase; the volume ratio of the extractant to the original acid is 1:2-5; Second step: counter-current contact washing of the loaded organic phase to obtain a washed organic phase; Third step: counter-current contact stripping of the washed organic phase to obtain a stripping solution and a regenerated organic phase; Fourth step: refining treatment of the stripping solution to obtain refined phosphoric acid; and recycling treatment of the regenerated organic phase to obtain a recyclable extractant.

[0016] Compared with the prior art, the present application has the following beneficial effects: 1. The application is a kind of extractant for wet-process phosphoric acid refining and its use method, the extractant includes ketone, alcohol, ether, ester, catalyst, demulsifier, the mass ratio of ketone: alcohol: ether: ester: catalyst: demulsifier is 70-80: 10-20: 1-5: 1-5: 0.5-1: 0.5-1;When applied, the extractant is added to the original acid, first, the carbonyl group in ketone and ester and the phosphorus-oxygen double bond are as strong hydrogen bond acceptors, and form stable hydrophobic complex with phosphoric acid molecules in the original acid, thereby driving the efficient transfer of phosphoric acid from aqueous phase to organic phase, in the process, alcohol directly binds to phosphoric acid molecules in the original acid through the bidirectional hydrogen bonding of its hydroxyl group, on the other hand, it interacts with the functional groups of ketone and ester, enhancing the stability and overall extraction capacity of the entire extraction network, at the same time, the ether effectively reduces the viscosity of the organic phase, optimizes the mass transfer kinetics and ensures the rapid and clear separation of the two phases, at the same time, the catalyst specifically destroys the interfacial barrier layer composed of colloidal impurities, greatly enhances the mass transfer efficiency, and the demulsifier can effectively break the emulsified foam formed by humic acid and beneficiation reagents and other organic impurities in the original acid at the interface of the two phases, so that the two phases are quickly separated, and the efficient extraction of phosphoric acid is finally completed, the application has the following advantages: First, ketone and ester form hydrophobic complex with phosphoric acid through carbonyl group and phosphorus-oxygen double bond, providing extraction driving force, alcohol enhances the stability of the extraction network through bidirectional hydrogen bonding, ether optimizes mass transfer and phase separation performance by adjusting system properties, the three work together to build a high-selectivity extraction system, realizing the efficient separation of phosphoric acid from complex aqueous phase system; Second, by introducing catalyst, the mass transfer barrier formed by colloidal impurities at the interface is effectively destroyed, the mass transfer kinetics of phosphoric acid from aqueous phase to organic phase is enhanced, and the phosphoric acid extraction rate is increased from 65%-70% of traditional process to 80%-92% with the help of demulsifier; Third, the demulsification of demulsifier on the interface of the two phases not only realizes the deep removal of impurities (more than 90% reduction of total amount of impurities), but also maintains the cleanliness of the interface and the unobstructed mass transfer channel, thereby ensuring the high extraction capacity of the extraction system and improving the overall extraction rate of the extraction system; Therefore, the application not only can extract phosphoric acid, but also significantly improves the extraction rate of phosphoric acid.

[0017] 2. In the application, the demulsifier is a zwitterionic polymer; when applied, the zwitterionic polymer synchronously neutralizes the surface charges of negatively charged anionic colloids and positively charged metal ion colloids through the synergistic effect of positive and negative centers in its molecular chain, promotes the efficient demulsification of colloidal system, greatly reduces the amount of impurities carried by phosphoric acid during the transfer to organic phase, and directly improves the product purity of extracted phosphoric acid. Therefore, the application not only has a high extraction rate of phosphoric acid, but also improves the purity of the final product.

[0018] 3. In this invention, an extractant for wet-process phosphoric acid refining and its application method are disclosed. The catalyst is a carboxylic acid or its derivative, specifically succinic acid, butenedioic acid, benzoic acid, and ethyl acetate, or any combination thereof. In application, firstly, the introduction of the carboxylic acid catalyst specifically disrupts the interfacial colloidal barrier layer, enhancing the mass transfer kinetics of phosphoric acid from the aqueous phase to the organic phase and improving single-stage extraction efficiency. Secondly, due to its mild chemical properties, this type of catalyst forms a stable system with ketone, ether, alcohol, and ester components, effectively inhibiting the chemical degradation and volatilization tendencies of the extractant components, improving the extractant recovery rate, reducing the cost of extractant use, and minimizing extractant loss during the recovery process. Simultaneously, this characteristic also reduces the emission of volatile organic compounds (VOCs), reducing environmental pollution. Finally, the catalyst, by mildly regulating the system's microenvironment, synergistically removes corrosive impurities such as fluorine and sulfur ions through deep purification, reducing equipment corrosion rates and extending equipment lifespan. Therefore, this invention not only improves the purity of the final product but also possesses excellent environmental and economic benefits.

[0019] 4. In the extractant and its application method for wet-process phosphoric acid purification of the present invention, the ether is any one or any combination of diallyl ether, diisopropyl ether, diisobutyl ether, diethylene glycol diethyl ether, ethylbutyl ether, and dipentyl ether; and the alcohol is any one or any combination of 2-propanol, cyclopentanol, n-butanol, isobutanol, n-pentanol, isopentanol, cyclohexanol, and 2-ethylhexanol. In application, the ether improves the hydrodynamic conditions for mixing and separating the two phases (aqueous and organic phases) by reducing the viscosity of the organic phase. Simultaneously, the alcohol (especially branched alcohols, such as 2-ethylhexanol) forms a dense molecular layer at the phase interface, inhibiting the adsorption of colloidal impurities at the interface and stabilizing the formation of the emulsion layer through steric hindrance. The synergistic effect of these two factors shortens the complete separation time of the two phases from approximately 20 minutes in the traditional process to less than 10 minutes, reducing the phase separation time and improving process efficiency. Therefore, the present invention not only possesses good environmental friendliness and economy but also reduces the phase separation time.

[0020] 5. In the present invention, an extractant for wet-process phosphoric acid refining and its application method, the ketone has a mass ratio of 70-80%, and the ether has a mass ratio of 1-5%. In application, this ratio of ketone and ether optimizes the mass transfer process while maintaining high selectivity in the extraction system. The higher mass ratio of ketone ensures efficient extraction and loading capacity of phosphoric acid, while the moderate mass ratio of ether promotes the rapid release of phosphoric acid into the aqueous phase during back-extraction by adjusting the polarity and density of the organic phase. The synergistic effect of this ratio of ketone and ether with the catalyst increases the initial concentration of dilute phosphoric acid after back-extraction from approximately 15% in traditional processes to over 40%. The increased concentration of the back-extraction solution reduces the evaporation load and energy consumption in the subsequent concentration stage, while also allowing for a smaller concentration equipment, thus reducing equipment investment and operating costs. Therefore, the present invention not only reduces phase separation time but also improves back-extraction performance and energy-saving effects. Attached Figure Description

[0021] Figure 1 This is a flowchart of the method for using the extractant of the present invention. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] See Figure 1 An extractant for wet-process phosphoric acid refining and its method of use, wherein the extractant comprises ketones, alcohols, ethers, esters, catalysts, and demulsifiers; The mass ratio of ketone: alcohol: ether: ester: catalyst: demulsifier is 70-80: 10-20: 1-5: 1-5: 0.5-1: 0.5-1.

[0024] The ketone is any one or any combination of 4-methyl-2-pentanone, 4-methyl-3-penten-2-one, methyl isopropyl ketone, diisopropyl ketone, diisobutyl ketone, and cyclohexanone.

[0025] The ether is any one or any combination of diallyl ether, diisopropyl ether, diisobutyl ether, diethylene glycol diethyl ether, ethyl butyl ether, and dipentyl ether.

[0026] The alcohol is any one or any combination of 2-propanol, cyclopentanol, n-butanol, isobutanol, n-pentanol, isopentanol, cyclohexanol, and 2-ethylhexanol.

[0027] The ester is any one or any combination of butyl isobutyrate, methyl isobutyrate, and tributyl phosphate.

[0028] The catalyst is a carboxylic acid or its derivative.

[0029] The carboxylic acids and their derivatives are any one or any combination of succinic acid, butylated succinic acid, benzoic acid, and ethyl acetate.

[0030] The demulsifier is an amphoteric polymer.

[0031] The zwitterionic polymer is polysulfobetaine.

[0032] The method of use includes: Step 1: The extractant is subjected to countercurrent contact extraction with the original acid to obtain a supported organic phase; the volume ratio of the extractant to the original acid is 1:2-5. Step 2: Perform countercurrent contact washing on the above-mentioned loaded organic phase to obtain a washed organic phase; Step 3: Perform contact back-extraction on the washed organic phase to obtain back-extraction solution and regenerated organic phase; Step 4: The above-mentioned back-extraction solution is purified to obtain purified phosphoric acid; at the same time, the regenerated organic phase is recycled to obtain a recyclable extractant.

[0033] The following are supplementary descriptions of the present invention: The extractant of this invention is prepared by the following method: First, weigh the corresponding ketone and ether according to the mass ratio of ketone: alcohol: ether: ester: catalyst: demulsifier = 70-80: 10-20: 1-5: 1-5: 0.5-1: 0.5-1; add them to a reaction vessel, stir at room temperature for 5-10 minutes until the solution is clear and stop stirring to obtain a ketone-ether mixed solution; while continuing to stir, add alcohol, ester, catalyst, and demulsifier to the ketone-ether mixed solution in sequence; then, continue stirring at room temperature for 20-30 minutes until the mixed solution becomes uniform and clear again, thus obtaining the extractant.

[0034] The original acid of this invention is prepared by the following method: First, crude phosphoric acid obtained by wet process is concentrated to obtain concentrated acid, wherein the mass percentage concentration of phosphorus pentoxide in the concentrated acid is 42%-45%; then, sodium carbonate is added to the concentrated acid to carry out a defluorination reaction to obtain defluorinated crude phosphoric acid, wherein the amount of sodium carbonate added for defluorination is 100%-120% of the stoichiometry of free fluoride ions in the concentrated acid; then, a settling agent is added to the defluorinated crude phosphoric acid for sedimentation separation to obtain precipitated clear acid and sludge acid; finally, activated carbon is added to the precipitated clear acid for decolorization treatment, wherein the amount of activated carbon added is 0.3%-0.8% of the mass of the precipitated clear acid; after decolorization, the mixture is filtered to obtain original acid that meets the extraction requirements.

[0035] Example 1: See Figure 1 An extractant for wet-process phosphoric acid refining and its method of use, wherein the extractant comprises ketones, alcohols, ethers, esters, catalysts, and demulsifiers; wherein the mass ratio of ketone:alcohol:ether:ester:catalyst:demulsifier is 70-80:10-20:1-5:1-5:0.5-1:0.5-1.

[0036] In application, after the extractant is added to the orthocyanin, ketones and esters, as the core extraction components, first form stable hydrophobic complexes with the phosphate molecules in the orthocyanin through their carbonyl and phosphorus-oxygen double bonds, acting as strong hydrogen bond acceptors. This drives the efficient and directional transfer of phosphate from the aqueous phase to the organic phase. During this process, alcohols, through the bidirectional hydrogen bonding of their hydroxyl groups, directly bind to the phosphate molecules in the orthocyanin, enhancing extraction efficiency. Simultaneously, they cross-link with the functional groups of ketones and esters, constructing a stable three-dimensional extraction network, thereby enhancing the system's stability and overall extraction capacity. Meanwhile, ethers effectively reduce... The low viscosity of the organic phase continuously optimizes mass transfer kinetics and ensures rapid and clear separation of the two phases. In synergy, the catalyst acts specifically on the phase interface, destroying the barrier layer composed of colloidal impurities and fundamentally eliminating mass transfer resistance. Meanwhile, the demulsifier effectively removes organic impurities such as humic acid and mineral processing reagents from the original acid. The emulsion foam formed at the two-phase interface enables rapid phase separation. The above-mentioned synergistic purification mechanism simultaneously completes the deep removal of impurities during the extraction of phosphoric acid. Finally, based on the completion of interface purification and mass transfer enhancement, high selectivity and high efficiency extraction of phosphoric acid are achieved. The mass ratio of each component is set based on a precise consideration of its functional synergy and performance balance: For ketones: as the main extractant, this ratio ensures sufficient phosphate complexation sites and high extraction capacity; if the content is too low (less than 70), the extraction capacity will be insufficient and the phosphate recovery rate will decrease; if the content is too high (greater than 80), the proportion of other functional components will be relatively insufficient, resulting in increased system viscosity and poor purification effect. For ethers: as a property modifier, this ratio can maintain the viscosity of the organic phase in the optimal range of 1.8-2.5 mPa·s; if the content is too low (less than 1), the mass transfer rate will decrease and phase separation will be difficult; if the content is too high (greater than 5), the effective extractable components will be over-diluted, resulting in a decrease in the extraction rate. For alcohols: if the content is too low (less than 10), the three-dimensional network stability is insufficient, the extraction capacity decreases and the interfacial tension increases, affecting the mass transfer efficiency; if the content is too high (greater than 20), the water content of the organic phase will increase significantly, leading to increased solvent loss. For esters: if the content is too low (less than 1), the synergistic extraction effect is insufficient and the phosphoric acid recovery rate decreases; if the content is too high (greater than 5), the viscosity of the organic phase will increase significantly and the phase separation time will be prolonged. For catalysts: if the content is too low (less than 0.5), the interfacial barrier layer will not be completely broken down, and the mass transfer efficiency will decrease; if the content is too high (greater than 1), the system will become too acidic, and the equipment corrosion rate will increase. For demulsifiers: if the content is too low (less than 0.5), the charge density is insufficient and the colloidal demulsification efficiency decreases; if the content is too high (greater than 1), the excessive positive and negative charge centers will restabilize the colloidal system, forming a stable microemulsion, which leads to a prolonged phase separation time.

[0037] Example 2: The basic content is the same as in Example 1, except that the ketone is any one or any combination of 4-methyl-2-pentanone, 4-methyl-3-penten-2-one, methyl isopropyl ketone, diisopropyl ketone, diisobutyl ketone, and cyclohexanone.

[0038] In applications, the main function of ketones is as strong hydrogen bond acceptors, forming hydrophobic complexes with phosphate molecules and providing the core driving force for extraction. Branched ketones (such as 4-methyl-2-pentanone) reduce side reactions while maintaining carbonyl complexing ability through moderate steric hindrance. Symmetrical dialkyl ketones (such as diisopropyl ketone) enhance the carbonyl oxygen electron cloud density and strengthen phosphate complexing ability by leveraging the electron-donating effect of alkyl groups. The rigid cyclic structure of cyclohexanone helps to regulate the fluid properties of the organic phase and form a densely packed layer at the interface. 4-methyl-3-penten-2-one further enhances its interaction with phosphate molecules by utilizing the π-electron synergistic effect of its unsaturated bonds. At the same time, the selected ketones all have suitable boiling points and viscosity characteristics, which can ensure that the phosphate partition coefficient remains within the optimized range while maintaining the main body proportion of the system and keeping solvent residue within a small range.

[0039] Example 3: The basic content is the same as in Example 1, except that the ether is any one or any combination of diallyl ether, diisopropyl ether, diisobutyl ether, diethylene glycol diethyl ether, ethyl butyl ether, and dipentyl ether.

[0040] In application, the main function of ethers is to regulate the physical properties of the organic phase, optimize mass transfer kinetics, and ensure rapid separation of the two phases. The selected ethers (such as diisopropyl ether and diisobutyl ether) effectively reduce the viscosity of the organic phase and optimize mass transfer due to their moderate polarity and branched structure. Diallyl ethers provide unique polarity regulation through their allyl structure. Diethylene glycol diethyl ether, with its high boiling point and polyether bond structure, enhances the back-extraction performance of the system while reducing volatilization losses. The synergistic effect of these ethers ensures the high efficiency and rapid phase separation of the extraction process.

[0041] Example 4: The basic content is the same as in Example 1, except that the alcohol is any one or any combination of 2-propanol, cyclopentanol, n-butanol, isobutanol, n-pentanol, isopentanol, cyclohexanol, and 2-ethylhexanol.

[0042] In application, the main function of alcohols is as bidirectional hydrogen-bonded bridging agents. On the one hand, they combine with phosphoric acid molecules in orthocyanins to enhance extraction efficiency; on the other hand, they crosslink with the functional groups of ketones and esters to construct a stable three-dimensional extraction network, thereby improving the overall extraction capacity and stability of the system. Among them, short-chain alcohols such as 2-propanol rapidly construct hydrogen-bonded networks due to their smaller steric hindrance; straight-chain alcohols such as n-butanol and n-pentanol enhance the directional alignment of the interface through regular alkyl chains, thereby improving extraction capacity; branched-chain alcohols such as isobutanol and isoamyl alcohol utilize their branched structures to generate a steric shielding effect, effectively preventing co-extraction of impurities; the rigid cyclic skeletons of cyclopentanol and cyclohexanol significantly enhance the stability of the three-dimensional network and reduce solvent loss; 2-ethylhexanol, as a representative of extra-long branched alcohols, forms a dense molecular layer at the phase interface, improving phase separation performance. This polyol system, through the combination of chain length regulation, branching design, and cyclic reinforcement, improves the stability of the extraction network, increases the phosphoric acid loading capacity, and keeps the residual solvent content within a small range while maintaining the ratio.

[0043] Example 5: The basic content is the same as in Example 1, except that the ester is any one or any combination of butyl isobutyrate, methyl isobutyrate, and tributyl phosphate.

[0044] In application, the main function of esters is as synergistic extractants. The phosphorus-oxygen double bond in their molecules acts as a strong hydrogen bond acceptor, working synergistically with ketones and ethers to form stable hydrophobic complexes with phosphate molecules in orthocyanins, thereby improving the selectivity and overall efficiency of the extraction system. Among them, butyl isobutyrate and methyl isobutyrate, with their branched alkyl structures, provide moderate steric hindrance, which helps improve the flowability of the organic phase while maintaining good extraction selectivity. Tributyl phosphate provides strong complexing sites through its phosphorus-oxygen double bond, enhancing its binding ability to phosphate molecules. The synergistic effect of these ester components maintains the extraction efficiency of the system while optimizing the properties of the organic phase and improving the phase separation effect.

[0045] Example 6: The basic content is the same as in Example 1, except that: the catalyst is a carboxylic acid and its derivatives; the carboxylic acid and its derivatives are any one or any combination of succinic acid, edematic acid, benzoic acid, and ethyl acetate.

[0046] In application, the main function of the catalyst is to specifically disrupt the mass transfer barrier layer formed by colloidal impurities at the phase interface, thereby enhancing the mass transfer kinetics of phosphoric acid from the aqueous phase to the organic phase. Simultaneously, its mild chemical properties inhibit the degradation and volatilization of the extractant components. The selected carboxylic acid catalysts exert synergistic catalytic effects through their specific molecular structures and acidic properties. Specifically, succinic acid and butenedioic acid, with their dicarboxylic acid structures, provide a moderately acidic environment and multidentate coordination ability, effectively disrupting the structure of interfacial colloidal impurities without causing equipment corrosion. Benzoic acid utilizes the steric effect and acidic characteristics of its aromatic ring structure to selectively promote the interfacial mass transfer process. Ethyl acetate provides a mild acidic microenvironment through its hydrolysis equilibrium, while its ester structure helps maintain the stability of the organic phase. The synergistic effect of these catalytic components enhances interfacial mass transfer kinetics while maintaining the chemical stability of the system, reducing solvent degradation and equipment corrosion, and ensuring the purity of the final product.

[0047] Example 7: The basic content is the same as in Example 1, except that the demulsifier is an amphoteric polymer.

[0048] In application, the main function of demulsifiers is to disrupt the stability of colloidal systems in orthoacids, promoting the destabilization and aggregation of fine colloidal impurities. The choice of zwitterionic polymers as demulsifiers is based on the fact that their molecular chains contain equal amounts of positive and negative charge centers, which can act simultaneously on negatively charged anionic colloids and positively charged metal cation colloids in orthoacids through a bidirectional charge neutralization effect, achieving efficient and broad-spectrum destabilization of the entire colloidal system and overcoming the limitation of single-charge type demulsifiers in terms of their limited range of action.

[0049] Example 8: The basic content is the same as in Example 1, except that the zwitterionic polymer is polysulfobetaine.

[0050] In application, the quaternary ammonium cation center of polysulfobetaine neutralizes the negatively charged anionic colloid surface charge, while the sulfonate anion center interacts with the positively charged metal cation. This bidirectional neutralization effect effectively disrupts the stability of the colloid, promoting the destabilization and aggregation of colloidal particles. Subsequently, the unstable colloidal particles aggregate, break down, settle, and separate into phases, thus achieving the purpose of demulsification.

[0051] Example 9: The basic content is the same as in Example 1, except that the method of use includes: Step 1: The extractant is subjected to countercurrent contact extraction with the original acid to obtain a supported organic phase; the volume ratio of the extractant to the original acid is 1:2-5. Step 2: Perform countercurrent contact washing on the above-mentioned loaded organic phase to obtain a washed organic phase; Step 3: Perform contact back-extraction on the washed organic phase to obtain back-extraction solution and regenerated organic phase; Step 4: The above-mentioned back-extraction solution is purified to obtain purified phosphoric acid; at the same time, the regenerated organic phase is recycled to obtain a recyclable extractant.

[0052] Example 10: The basic content is the same as in Example 9, except that: In the first step, the extractant and the original acid are subjected to countercurrent contact extraction to obtain a loaded organic phase; the volume ratio of extractant to original acid of 1:2-5 means that the volume ratio of extractant to original acid is controlled at 1:2-5, and multi-stage countercurrent contact is performed; after extraction, the phases are separated by standing, the upper layer is the loaded organic phase rich in phosphoric acid, and the lower layer is the raffinate enriched with impurities, and the raffinate is discharged from the system as waste liquid; In the second step, the countercurrent contact washing of the above-mentioned loaded organic phase to obtain the washed organic phase refers to: introducing the above-mentioned loaded organic phase into the washing section, controlling the volume ratio of the loaded organic phase to the washing water to be 5-15:1, and performing countercurrent washing; after washing, phase separation is performed to obtain a washed organic phase with improved purity, and the washing water containing a small amount of phosphoric acid and soluble impurities is discharged. In the third step, the contact back-extraction of the washed organic phase refers to: mixing the washed organic phase with distilled water in a back-extraction device at a volume ratio of 6-20:1, so that phosphoric acid is transferred from the organic phase to the aqueous phase; after back-extraction, the phases are separated to obtain a back-extraction solution rich in phosphoric acid and a regenerated organic phase in which phosphoric acid has been stripped. In the fourth step, the purification of the above-mentioned back-extraction solution to obtain refined phosphoric acid, and the recovery of the regenerated organic phase to obtain a recyclable extractant, refers to: evaporating and concentrating the above-mentioned back-extraction solution under normal or reduced pressure to remove some water, obtaining refined phosphoric acid with a mass percentage concentration of 75%-85%; simultaneously, recovering the regenerated organic phase to obtain a recyclable extractant; the mass percentage concentration of the refined phosphoric acid is 75%-85%.

[0053] Example 11: The basic content is the same as in Example 10, except that the above-mentioned back-extraction solution is subjected to subsequent purification treatments including but not limited to the following: Primary refining process: The refined phosphoric acid is subjected to desulfurization, concentration, and decolorization processes sequentially to obtain high-quality phosphoric acid; the high-quality phosphoric acid has a phosphoric acid mass percentage concentration of greater than or equal to 85%. Food-grade refining process: The high-quality phosphoric acid is subjected to defluorination, lead removal, arsenic removal and aeration refining in sequence to obtain food-grade phosphoric acid.

[0054] Example 12: The basic content is the same as in Example 1, except that: the extractant is first added to the original acid to obtain a mixed solution; the original acid is pretreated wet-process phosphoric acid, and the mass percentage concentration of phosphorus pentoxide in the original acid is 42wt%-48wt%; the mass ratio of ketone to ether in the extractant is 70-80:1-5; and the mass percentage concentration of catalyst in the extractant is 1%.

[0055] When applying, follow these steps: Step 1: Perform seven-stage countercurrent extraction on the mixed solution of the extractant and the original acid, controlling the volume ratio of the organic phase to the aqueous phase (O:A) to be 3:1, to obtain the loaded organic phase; Step 2: Perform four-stage countercurrent washing on the above-mentioned loaded organic phase, controlling the washing ratio (O:A) to be 12:1, to obtain the washed organic phase; Step 3: Perform three-stage countercurrent back-extraction on the washed organic phase, controlling the back-extraction ratio (O:A) to be 6:1, to obtain the back-extraction solution and the regenerated organic phase; Step 4: The above-mentioned back-extraction solution is successively concentrated, desulfurized, and decolorized and filtered to obtain an 85wt% phosphoric acid product; at the same time, the above-mentioned regenerated organic phase is recovered to obtain a recyclable extractant. According to the test, the extraction rate of phosphoric acid in this embodiment reached 82.2%, and the contents of each impurity in the phosphoric acid product were as follows: sulfate ≤0.002%, fluorine ≤0.0005%, iron ≤0.001%, arsenic ≤0.0002%, heavy metals (calculated as lead) ≤0.0009%, and chlorides (calculated as chlorine) ≤0.0005%.

[0056] Example 13: The basic content is the same as in Example 1, except that: the extractant is first added to the original acid to obtain a mixed solution; the original acid is pretreated wet-process phosphoric acid, and the mass percentage concentration of phosphorus pentoxide in the original acid is 42wt%-48wt%; the mass ratio of ketone: alcohol: ether: ester: catalyst: zwitterionic polymer (polysulfobetaine) in the extractant is 79:10:5:5:0.5:0.5.

[0057] When applying, follow these steps: Step 1: Perform seven-stage countercurrent extraction on the mixed solution of the extractant and the original acid, controlling the volume ratio of the organic phase to the aqueous phase (O:A) to be 2.5:1, to obtain the loaded organic phase; Step 2: Perform four-stage countercurrent washing on the above-mentioned loaded organic phase, controlling the washing ratio (O:A) to be 6.5:1, to obtain the washed organic phase; Step 3: Perform three-stage countercurrent back-extraction on the washed organic phase, controlling the back-extraction ratio (O:A) to be 4:1, to obtain the back-extraction solution and the regenerated organic phase; Step 4: The above-mentioned back-extraction solution is successively concentrated, desulfurized, and decolorized and filtered to obtain an 85wt% phosphoric acid product; at the same time, the above-mentioned regenerated organic phase is recovered to obtain a recyclable extractant. According to the test, the extraction rate of phosphoric acid in this embodiment reached 86.2%, and the contents of each impurity in the phosphoric acid product were as follows: sulfate ≤0.002%, fluorine ≤0.0007%, iron ≤0.002%, arsenic ≤0.0003%, heavy metals (calculated as lead) ≤0.0010%, and chlorides (calculated as chlorine) ≤0.0006%.

[0058] Example 14: The basic content is the same as in Example 1, except that: the extractant is first added to the original acid to obtain a mixed solution; the original acid is pretreated wet-process phosphoric acid, and the mass percentage concentration of phosphorus pentoxide in the original acid is 42wt%-48wt%; the mass ratio of ketone: alcohol: ether: ester: catalyst: zwitterionic polymer (polysulfobetaine) in the extractant is 70:18:5:5:1:1.

[0059] When applying, follow these steps: Step 1: Perform seven-stage countercurrent extraction on the mixed solution of the extractant and the original acid, controlling the volume ratio of the organic phase to the aqueous phase (O:A) to be 5:1, to obtain the loaded organic phase; Step 2: Perform four-stage countercurrent washing on the above-mentioned loaded organic phase, controlling the washing ratio (O:A) to be 7.25:1, to obtain the washed organic phase; Step 3: Perform three-stage countercurrent back-extraction on the washed organic phase, controlling the back-extraction ratio (O:A) to be 6:1, to obtain the back-extraction solution and the regenerated organic phase; Step 4: The above-mentioned back-extraction solution is successively concentrated, desulfurized, and decolorized and filtered to obtain an 85wt% phosphoric acid product; at the same time, the above-mentioned regenerated organic phase is recovered to obtain a recyclable extractant. According to the test, the extraction rate of phosphoric acid in this embodiment reached 88.2%, and the contents of each impurity in the phosphoric acid product were as follows: sulfate ≤0.002%, fluorine ≤0.0005%, iron ≤0.001%, arsenic ≤0.0009%, heavy metals (calculated as lead) ≤0.0009%, and chlorides (calculated as chlorine) ≤0.0004%.

[0060] The above description is only a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Any equivalent modifications or changes made by those skilled in the art based on the content disclosed in the present invention should be included within the scope of protection set forth in the claims.

Claims

1. An extractant for wet-process phosphoric acid refining, characterized by: The extractant includes ketone, alcohol, ether, ester, catalyst, demulsifier; The ketone: The mass ratio of alcohol: ether: ester: catalyst: demulsifier is 70-80: 10-20: 1-5: 1-5: 0.5-1: 0.5-1.

2. An extractant for wet-process phosphoric acid refining according to claim 1, characterized in that: The ketone is any one or any combination of 4-methyl-2 pentanone, 4-methyl-3-penten-2-one, methyl isopropyl ketone, diisopropyl ketone, diisobutyl ketone, cyclohexanone.

3. An extractant for wet-process phosphoric acid refining according to claim 1, characterized in that: The ether is any one or any combination of diallyl ether, diisopropyl ether, diisobutyl ether, diethylene glycol diethyl ether, ethyl butyl ether, dipentyl ether.

4. An extractant for wet-process phosphoric acid refining according to claim 1, characterized in that: The alcohol is any one or any combination of 2-propanol, cyclopentanol, n-butanol, isobutyl alcohol, n-pentanol, isoamyl alcohol, cyclohexanol, 2-ethylhexanol.

5. An extractant for wet-process phosphoric acid refining according to claim 1, characterized in that: The ester is any one or any combination of butyl isobutyrate, methyl isobutyrate, tributyl phosphate.

6. An extractant for wet-process phosphoric acid refining according to claim 1, characterized in that: The catalyst is carboxylic acid and its derivatives.

7. An extractant for the wet-process phosphoric acid purification according to claim 6, characterized by the fact that: The carboxylic acid and its derivatives are any one or any combination of succinic acid, butenedioic acid, benzoic acid, ethyl acetate.

8. An extractant for wet-process phosphoric acid refining according to any one of claims 1 to 6, characterized in that: The demulsifier is a zwitterionic polymer.

9. An extractant for the wet-process phosphoric acid purification according to claim 8, characterized by the fact that: The zwitterionic polymer is polysulfobetaine.

10. A method of use of an extractant for wet-process phosphoric acid refining according to any one of claims 1-6, characterized in that: The use method includes: First step: the extractant is contacted with the original acid in countercurrent to extract, and the loaded organic phase is obtained; the volume ratio of the extractant to the original acid is 1:2-5; Second step: the loaded organic phase is washed in countercurrent to obtain a washed organic phase; Third step: the washed organic phase is contacted to back extract to obtain a back extraction liquid and a regenerated organic phase; Fourth step: the back extraction liquid is refined to obtain refined phosphoric acid; at the same time, the regenerated organic phase is recycled to obtain a recyclable extractant.

Images