A method for preparing phosphate based on hydrochloric acid decomposition of phosphate rock

Abstract

This application relates to the field of phosphate product preparation technology, and more particularly to a method for preparing phosphate based on hydrochloric acid decomposition of phosphate rock. The method includes: pulping phosphate rock to obtain a phosphate rock slurry; sequentially acidifying and filtering the phosphate rock slurry to obtain an intermediate filter material; pre-extracting the intermediate filter material using tributyl phosphate to obtain a pre-extracted filter material; extracting the pre-extracted filter material using a composite extractant comprising triethylamine, tributyl phosphate, trioctylamine, and a long-chain fatty alcohol modifier to obtain a calcium-containing aqueous phase and a supported organic phase; sequentially back-extracting the supported organic phase to obtain a dicalcium phosphate product and industrial-grade phosphoric acid; neutralizing the two to obtain a calcium phosphate product; sequentially precipitating and filtering the calcium-containing aqueous phase, wherein the calcium chloride filtrate is concentrated to obtain a calcium chloride product, and the mixed precipitation is calcined to obtain a metal oxide concentrate; the extraction is carried out in a rotary microchannel device including a hollow fiber membrane. This method improves the purity of the phosphoric acid product and the utilization rate of the phosphate rock.

Description

Technical Field

[0001] This application relates to the field of phosphate product preparation technology, and in particular to a method for preparing phosphate based on hydrochloric acid decomposition of phosphate rock. Background Technology

[0002] The utilization of low- to medium-grade phosphate rock involves decomposing it into phosphoric acid products. This decomposition process is divided into high-temperature pyrolysis and wet leaching decomposition, depending on the method. High-temperature pyrolysis involves thermally decomposing the phosphate rock at high temperatures to produce phosphoric acid gas. This method is energy-intensive and requires a certain phosphorus content in the phosphate rock. Wet leaching decomposition uses an acidic solution to treat the phosphate rock, allowing it to decompose in the acidic environment. Acidic solutions include sulfuric acid, nitric acid, and hydrochloric acid. In the case of hydrochloric acid, wet leaching decomposition not only produces phosphoric acid but also calcium chloride and hydrogen fluoride. The specific reaction flow is: Ca5F(PO4)3 + 10HCl → 3H3PO4 + 5CaCl2 + HF↑.

[0003] During the wet leaching decomposition process, if the phosphate rock contains F and Si, SiF4 gas will be generated. Part of the generated SiF4 gas will escape directly, while the remaining SiF4 gas will be converted into residual fluorosilicic acid. The relevant reaction processes are: SiO2 + 4HF → SiF4↑ + 2H2O, SiF4 + 2HF → H2SiF6. Simultaneously, oxide impurities in the phosphate rock will also be decomposed, and some oxides will also generate gas and form corresponding salt components. These salt components will remain in the phosphoric acid, affecting the purity of the phosphoric acid. The relevant reaction processes are: CaC... O3·MgCO3 + 4HCl → CaCl2 + MgCl2 + 2H2O + 2CO2↑, Al2O3 + 6HCl → 2AlCl3 + 3H2O, Fe2O3 + 6HCl → 2FeCl3 + 3H2O. Furthermore, if the amount of hydrochloric acid used in the wet leaching decomposition process is insufficient, it will lead to incomplete decomposition of the phosphate rock, simultaneously generating calcium dihydrogen phosphate chloride. The specific reaction is: Ca5F(PO4)3 + 7HCl + 3H2O → 3CaCl(H2PO4)·H2O↓ + 2CaCl2 + HF↑. The generated calcium dihydrogen phosphate chloride crystals are very fine, making the slurry produced by the phosphate rock decomposition viscous and difficult to filter. Therefore, during the wet leaching decomposition process, phosphoric acid needs to be separated and purified to avoid the residue of fine calcium dihydrogen phosphate chloride.

[0004] However, after phosphate rock is decomposed by wet leaching, some salt components formed by metal oxides may remain in the phosphoric acid product. This not only affects the purity of the phosphoric acid product, but also causes a waste of metal oxide resources and affects the utilization of phosphate rock. Summary of the Invention

[0005] This application provides a method for preparing phosphate based on hydrochloric acid decomposition of phosphate rock, in order to solve the following technical problem: how to improve the purity of phosphate products and the utilization rate of phosphate rock.

[0006] In a first aspect, embodiments of this application provide a method for preparing phosphate based on the hydrochloric acid decomposition of phosphate rock, wherein the phosphate rock comprises metal oxides and calcium, and the method includes: Phosphate ore is pulped to obtain phosphate ore slurry; The phosphate rock slurry was subjected to an acid hydrolysis reaction using hydrochloric acid to obtain an acid hydrolyzed slurry. The acid-hydrolyzed slurry is filtered to obtain intermediate filter material; The intermediate filter media was pre-extracted using tributyl phosphate to obtain pre-extracted filter media; The pre-extraction filter material was extracted using a composite extractant to obtain a calcium-containing aqueous phase and a supported organic phase. The supported organic phase was back-extracted using water to obtain dicalcium phosphate product and industrial-grade phosphoric acid. A portion of the industrial-grade phosphoric acid and the dicalcium phosphate product are sequentially subjected to neutralization reactions and pH adjustments to obtain the calcium phosphate product. The calcium-containing aqueous phase was subjected to precipitation and filtration in sequence to obtain calcium chloride filtrate and mixed precipitate; The calcium chloride filtrate was concentrated to obtain the calcium chloride product; The mixed precipitate was calcined to obtain a metal oxide concentrate. The extraction is carried out in a rotary microchannel device, which includes a hollow fiber membrane disposed in the hydrophobic section of the rotary microchannel device. The composite extractant comprises a mixed organic phase of triethylamine, tributyl phosphate, trioctylamine, and a long-chain fatty alcohol modifier, wherein the mass fraction of trioctylamine is greater than the mass fraction of tributyl phosphate and greater than the mass fraction of triethylamine.

[0007] Optionally, based on the mass fraction of the composite extractant, the mixed organic phase comprises: trioctylamine: 20% to 35%, tributyl phosphate: 10% to 25%, triethylamine: 5% to 15%, and long-chain fatty alcohol modifier: 2% to 8%.

[0008] Optionally, the composite extractant may further include sulfonated kerosene, wherein the sulfonated kerosene has a mass fraction of 35% to 55%.

[0009] Optionally, the volume V1 of the composite extractant and the volume V2 of the intermediate filter material satisfy: V1:V2=1:(6 to 10).

[0010] Optionally, the volume V3 of the water and the volume V4 of the supported organic phase satisfy: V3:V4 = (3 to 10):1; and / or The back-extraction is performed 2 to 4 times.

[0011] Optionally, the acidolysis reaction is carried out at a temperature of 25°C to 30°C for a duration of 20 min to 30 min; and / or The target particle size for filtration is 0.5 mm to 1.5 mm.

[0012] Optionally, the gap between the microchannels in the rotary microchannel device is 1.0 mm to 3.0 mm.

[0013] Optionally, the hollow fiber membrane has a pore size of 50 nm to 80 nm; and / or The thickness of the hollow fiber membrane is 2 mm to 5 mm.

[0014] Optionally, the volume V5 of the first tributyl phosphate and the volume V2 of the intermediate filter material satisfy: V5:V2 = 1:(8 to 15); and / or The mass m1 of the industrial-grade phosphoric acid and the mass m2 of the dicalcium phosphate product satisfy: m1:m2 = (1 to 3):(5 to 10); and / or The mass of the industrial-grade phosphoric acid is 30% to 70% of the total mass of the industrial-grade phosphoric acid.

[0015] Optionally, the neutralization reaction is carried out at a temperature of 40°C to 80°C for a duration of 30 min to 120 min; and / or The calcination temperature is 400℃ to 800℃, and the calcination time is 1h to 4h.

[0016] The technical solutions provided in this application have the following advantages compared with the prior art: This application provides a method for preparing phosphate based on hydrochloric acid decomposition of phosphate rock. The method first involves pulping the phosphate rock to remove insoluble matter. Then, hydrochloric acid is used to perform an acid hydrolysis reaction on the phosphate rock pulp. The hydrochloric acid reacts with the highly acid-soluble ions in the phosphate rock, causing fluoride ions to form calcium fluoride precipitate and detach from the liquid phase. Next, filtration removes the acid-insoluble precipitate and solid impurities such as slag, resulting in an intermediate filter medium containing only soluble phosphoric acid, calcium chloride, and trace impurities, thus pre-removing fluoride impurities at the source. Subsequently, the specific separation capability of tributyl phosphate for the fluoride-containing components of the intermediate filter medium is utilized to transfer residual HF, H₂SiF₆, etc., to the pre-extraction organic phase in advance, while simultaneously removing some metal complexes, reducing the impurity load of the main extraction, and preventing extractant deactivation and the formation of a third phase. Next, a mixed organic phase composite extractant containing triethylamine, tributyl phosphate, trioctylamine, and long-chain fatty alcohol modifiers was used, and the gradient mass fractions of triethylamine, tributyl phosphate, and trioctylamine were controlled: trioctylamine can be protonated in the strong acid environment of hydrochloric acid, selectively complexing phosphate ions into the organic phase to form an amine-phosphate complex; tributyl phosphate can enhance the extraction rate of trioctylamine, adjust the polarity of the mixed organic phase, inhibit the formation of third-phase impurities, and reduce the entrainment of impurities in the aqueous phase, so as to remove residual fluoride in the intermediate filter material; triethylamine can supplement the active sites of trioctylamine, accelerate the mass transfer rate of the composite extractant, and avoid co-extraction of impurities; long-chain fatty alcohol modifiers occupy amine salt sites through hydrogen bonds, form an interfacial water molecule repulsion layer, and inhibit the co-extraction of metal complex anions such as Fe, Al, and Mg. Furthermore, the extraction process is confined within a rotating microchannel device. Leveraging the small size and high shear force of this device, mass transfer efficiency during extraction is enhanced, the window time for impurity co-extraction is shortened, the extraction phase separation effect is strengthened, and entrainment of impurities in the aqueous phase is eliminated, ensuring that only high-purity phosphoric acid enters the organic phase. Simultaneously, a hollow fiber membrane is installed within the rotating microchannel device to segment and guide hydrophobically encapsulated particles, preventing impurities from penetrating. Then, water back-extraction disrupts the equilibrium of the amine phosphate complex, quantitatively transferring phosphoric acid to the aqueous phase, while remaining impurities containing fluoride ions remain in the organic phase. This achieves secondary purification of phosphoric acid, completing deep defluorination and purification to obtain high-purity phosphoric acid and dicalcium phosphate products. Subsequently, the produced phosphoric acid and dicalcium phosphate products are subjected to neutralization reactions and pH adjustments to prepare high-value calcium phosphate products. Simultaneously, the calcium-containing aqueous phase obtained from extraction is subjected to precipitation and filtration to precipitate the metal hydroxides mixed in it, resulting in a calcium chloride filtrate with a certain purity. Finally, the impurities entrained in the calcium chloride solution are precipitated by concentration to obtain a calcium chloride product with higher purity. The precipitated mixed precipitate can be calcined to form a metal oxide concentrate, thereby completing the full recovery of phosphate rock and improving the utilization rate of phosphate rock. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A flowchart of a method for preparing phosphate based on hydrochloric acid decomposition of phosphate rock is provided in this application embodiment; Figure 2 A process flow diagram of a method for preparing phosphate based on hydrochloric acid decomposition of phosphate rock is provided in this application embodiment; Figure 3 This is a schematic diagram of the composite extractant provided in the embodiments of this application after being washed twice with water. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] The range descriptions used in this application, such as numerical ranges and proportional ranges, include all possible sub-ranges and single numerical values ​​within that range. For example, the range descriptions of "1 to 6" or "1~6" cover all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms "comprising" and others used herein mean "including but not limited to"; relational terms such as "first" and "second" are used only to distinguish different entities or operations and do not imply an actual order or relationship; "and / or" indicates that multiple situations can exist individually or simultaneously; expressions such as "at least one," "multiple," and "at least one" refer to any combination of the corresponding objects, including combinations of single or multiple objects. The proportional relationships involved in this document, such as mass ratios and molar ratios, should be understood as the correspondence between the first and second terms of a proportional formula, according to the order of description. The raw materials, reagents, instruments, and equipment used herein can all be obtained by purchasing from the market or by existing methods.

[0022] It should be noted that during the wet leaching and decomposition process to prepare phosphoric acid, calcium in the phosphate rock will form a water-soluble CaCl2 component, increasing the Ca content in the solution. 2+ At relatively high concentrations, within a certain pH range, the CaF2 precipitation reaction proceeds more completely through the common ion effect. Therefore, the solution in the wet acidolysis process captures free F during defluorination. - This process leads to the formation of CaF2 precipitate, which promotes the defluorination process. Therefore, the removal of fluorine is crucial for improving the purity of phosphoric acid.

[0023] It should be noted that during the wet leaching decomposition process, if metal oxides are present in the phosphate rock, metal salts will be formed to some extent. Most of these metal salts can be removed through extraction and other operations, but a small amount of metal salts will still remain in the phosphoric acid. Therefore, if this part of the metal salts can be separated from the phosphoric acid, the utilization rate of the phosphate rock can be improved.

[0024] Figure 1 An exemplary schematic diagram of a method for preparing phosphate based on hydrochloric acid decomposition of phosphate rock is shown in an embodiment of this application; Figure 2 An exemplary process flow diagram of a method for preparing phosphate based on hydrochloric acid decomposition of phosphate rock is shown in the embodiments of this application; like Figure 1 and Figure 2 As shown in the embodiments of this application, a method for preparing phosphate based on hydrochloric acid decomposition of phosphate rock is provided. The phosphate rock includes metal oxides and calcium. The method includes: S1. Pulverize the phosphate rock to obtain phosphate slurry; S2. The phosphate rock slurry is subjected to an acid hydrolysis reaction using hydrochloric acid to obtain an acid hydrolyzed slurry; S3. Filter the acid-hydrolyzed slurry to obtain intermediate filter material; S4. The intermediate filter material is pre-extracted using tributyl phosphate to obtain a pre-extracted filter material; S5. Extract the pre-extracted filter material using a composite extractant to obtain a calcium-containing aqueous phase and a supported organic phase; S6. The supported organic phase is back-extracted using water to obtain dicalcium phosphate product and industrial-grade phosphoric acid; S7. A portion of the industrial-grade phosphoric acid and the dicalcium phosphate product are subjected to a neutralization reaction and pH adjustment in sequence to obtain the calcium phosphate product; S8. The calcium-containing aqueous phase is subjected to precipitation and filtration sequentially to obtain calcium chloride filtrate and mixed precipitate; S9. Concentrate the calcium chloride filtrate to obtain the calcium chloride product; S10. The mixed precipitate is calcined to obtain a metal oxide concentrate; The extraction is carried out in a rotary microchannel device, which includes a hollow fiber membrane disposed in the hydrophobic section of the rotary microchannel device. The composite extractant comprises a mixed organic phase of triethylamine, tributyl phosphate, and trioctylamine, wherein the mass fraction of trioctylamine is greater than the mass fraction of tributyl phosphate and greater than the mass fraction of triethylamine.

[0025] It should be noted that the main component of phosphate rock is calcium fluorophosphate Ca5F(PO4)3, but it also contains phosphate impurities of other metal cations (Fe, Mg, Al, etc.) and non-metal ions (As, Si, F, etc.). These impurities undergo complex chemical reactions with industrial hydrochloric acid. During these numerous chemical reactions, fluoride ions can be removed through defluorination processes (extraction and back-extraction), while impurities such as Fe, Mg, and Al can be removed in the dicalcium phosphate product (white fertilizer) produced by back-extraction. Therefore, by improving the reaction selectivity of the extraction stage, fluoride and phosphoric acid can be effectively separated to obtain a high-purity phosphoric acid product.

[0026] It should be noted that the mass concentration of hydrochloric acid used in this acidolysis reaction can be 20% to 30%.

[0027] It should be noted that the extractants used in traditional wet acid hydrolysis processes are generally: (1) phosphate esters: including tributyl phosphate (TBP), tributoxyethyl phosphate, etc.; (2) long-chain tertiary amines: trioctylamine (N235, a mixture of C8 to C10 trialkylamines), dioctadecyl dimethyl ammonium chloride, etc.; (3) alcohols, ethers or ketones: n-butanol, isooctyl alcohol, methyl isobutyl ketone, etc. These extractants share the common characteristics of having long carbon chains, low volatility, and better selectivity for extracting phosphoric acid and hydrochloric acid.

[0028] It should be noted that the rotary microchannel device used in this extraction can be a microchannel device as shown in CN202410973262.X. The rotary microchannel device consists of a hollow fiber membrane, an inner cylinder, and an outer cylinder. The outer cylinder is sleeved around the inner cylinder, and a microchannel is formed between the outer cylinder and the inner cylinder. The outer wall of the outer cylinder is provided with an inlet, an upper outlet, and a lower outlet. The upper outlet and the lower outlet are respectively located on one side of the outer wall of the outer cylinder, and the inlet is located on the other side of the outer wall of the outer cylinder, so as to divide the microchannel into an oleophilic section and a hydrophilic section. With the horizontal plane where the lower end of the inlet is located as the reference plane, the material of the inner cylinder and the outer cylinder above the reference plane is a hydrophobic material, and the material of the inner cylinder and the outer cylinder below the reference plane is a hydrophilic material. The filtration section includes at least one hollow fiber membrane. The hollow fiber membrane is made of hydrophobic material and is positioned between the inlet and the top outlet. One end of the hollow fiber membrane is spaced at a predetermined distance from the outer wall of the inner cylinder. During the operation of this rotary microchannel device, the intermediate filter material and the composite extractant are mixed in a pre-mixing tank and then enter the rotary microchannel through the inlet for extraction. Since the mixed organic phase in the composite extractant forms hydrophobic encapsulated particles of water-in-oil and mineral particles, as well as hydrophilic encapsulated particles of oil-in-oil and mineral particles, during the extraction stage, the hydrophobic encapsulated particles are guided by the hydrophobic material into the upper section of the inner and outer cylinders for mixing and extraction, while the hydrophilic encapsulated particles are guided by the hydrophilic material into the lower section of the inner and outer cylinders for mixing and extraction. Larger hydrophobic encapsulated particles are repeatedly mixed, extracted, and separated in the middle region of the inner and outer cylinders under the obstruction of the hollow fiber membrane, thus finally obtaining a fully extracted loaded organic phase from the top outlet.

[0029] It should be noted that a filter screen can be introduced for filtration in the later stages of this back-extraction. This back-extraction needs to be carried out in a reaction vessel equipped with a stirrer, and the stirring speed can be 200 r / min to 300 r / min.

[0030] It should be noted that this back-extraction can also yield a portion of the composite extractant. This portion of the composite extractant can be regenerated by undergoing multiple washing, filtration, and concentration processes. Specifically, the composite extractant after two washings... Figure 3 As shown, it still maintains a certain degree of stability.

[0031] It should be noted that this calcium chloride product can be a liquid calcium chloride product with a mass concentration of 15% or higher, or a solid calcium chloride product with a purity of 90% or higher. The mass concentration of this calcium chloride can be determined according to the specific concentration method.

[0032] It should be noted that the mass concentration of phosphate in the loaded organic phase can be 35% to 40%, which is an order of magnitude higher than the mass concentration range of traditional wet acid leaching, and can cover more medium and low grade phosphate rocks.

[0033] It should be noted that the calcium-containing aqueous phase can first be precipitated with an alkaline reagent (e.g., a 25% calcium carbonate solution) to remove metal elements. Then, calcium hydroxide is added to adjust the calcium-containing aqueous phase to neutral. If the phosphate rock contains Mg, calcium hydroxide is continued to be added until the pH value is within the range of 9 to 10, causing Mg to form magnesium hydroxide precipitate, resulting in a mixed precipitate containing metal hydroxide precipitates. This mixed precipitate can be directly calcined to form the corresponding metal oxide concentrate, thereby completing the recovery of the metal oxides.

[0034] It should be noted that the method for preparing phosphate based on hydrochloric acid decomposition of phosphate rock provided in this application embodiment improves the purity of phosphate from three dimensions: the source, process, and end of impurity removal. This is achieved through a six-stage progressive mechanism: pre-extraction and pre-purification + gradient synergistic extraction + microchannel enhanced phase separation + back-extraction secondary purification + terminal solid-liquid separation + full element resource utilization. Simultaneously, it maximizes the utilization of phosphate rock through the full-scale productization of phosphorus, calcium, and metal oxides. The specific mechanism is as follows: I. Mechanisms for improving the purity of phosphoric acid products.

[0035] 1. Pre-extraction and impurity removal: Reduce the impurity load of the main extraction system.

[0036] In the traditional hydrochloric acid decomposition process of phosphate rock, the intermediate filter material directly enters the main extraction stage, containing residual fluorine-containing components such as HF and H2SiF6, as well as some Fe. 3+ Al 3+ Metal ions can compete with the main extractant for active sites, or cause emulsification of the extraction system and the formation of a third phase, which can eventually be carried into the organic phase and contaminate the phosphoric acid product.

[0037] This method adds a pre-extraction step of tributyl phosphate (TBP) after filtration. Utilizing TBP's specific separation capability for fluorine-containing components, residual HF, H₂SiF₆, etc., in the intermediate filter material are transferred to the pre-extraction organic phase in advance, while simultaneously removing some metal complexes. This pretreatment achieves: (1) Reduced burden at the source: The concentration of impurities faced in the main extraction stage is significantly reduced. The ternary composite extractant can focus on the selective complexation of phosphate groups, avoiding co-extraction caused by "competitive extraction of impurities". (2) System protection: Reduce the protonation interference of fluorosilicic acid on subsequent amine extractants, prevent extractant deactivation, and ensure long-term stability of extraction selectivity.

[0038] 2. Synergistic effect of ternary gradient composite extractant and long-chain fatty alcohol modifier: precise targeted extraction, maximizing the suppression of impurity co-extraction.

[0039] The composite extractant uses a gradient ratio of trioctylamine > tributyl diphosphate > triethylamine by mass fraction, and adds 2% to 8% by mass of long-chain fatty alcohol modifiers (such as isooctanol, n-octanol, or decanol) to form a functional zone of "main extraction + co-extraction + mass transfer aid + metal inhibition". (1) Main extractant: Trioctylamine with a mass fraction of 20% to 35% can be protonated in a strongly acidic environment and react with H2PO4. - Electrostatic complexation generates hydrophobic ion pairs, and the long carbon chain structure of the hydrophobic ion pairs affects Ca. 2+ Mg 2+ Fe 3+ Al 3+Cl - Almost no extraction is required, blocking impurity co-extraction at the molecular level.

[0040] (2) Co-extractant + phase regulator: Tributyl phosphate with a mass fraction of 10% to 25% can provide P=O bond to form hydrogen bond with the -OH group of phosphate, thus synergistically improving the extraction rate; Tributyl phosphate can also precisely adjust the polarity of the organic phase, inhibit the formation of the third phase, reduce the entrainment of the aqueous phase (impurity carrier), and further remove residual fluorine.

[0041] (3) Mass transfer promoter: Triethylamine with a mass fraction of 5% to 15% can supplement active sites, increase the rate of extraction reaction, and shorten the equilibrium time of extraction reaction; at the same time, triethylamine can also regulate the interfacial tension and strengthen the contact between the aqueous phase and the organic phase; in addition, the low content of triethylamine can avoid the impurity entrainment caused by the strong water solubility of short carbon chains.

[0042] (4) Metal inhibitor modifier: Long-chain fatty alcohols with a mass fraction of 2% to 8% can form hydrogen bond complexes with the amino group of protonated trioctylamine through the hydroxyl group, occupy the active site of the amine salt, and reduce R3NH + With [FeCl4] - [AlCl4] - This allows for the coordination opportunities of metal complex anions; at the same time, long-chain fatty alcohol molecules form a water molecule repulsion layer at the organic-aqueous phase interface, hindering the interfacial mass transfer channels for the migration of metal complex anions to the organic phase, thereby locking metal ions such as Fe, Al, and Mg in the calcium-containing aqueous phase (raffinate), preventing metal impurities from being lost to the organic phase during the extraction stage and contaminating phosphoric acid.

[0043] The four components—trioctylamine, tributyl phosphate, triethylamine, and long-chain fatty alcohol modifier—work synergistically to significantly improve the extraction rate of phosphoric acid, while impurities such as metal ions and chloride ions are fixed in the raffinate, resulting in a substantial increase in the purity of the organic phase.

[0044] 3. Rotary microchannel equipment: enhances mass transfer and phase separation, and eliminates physical entrainment.

[0045] The extraction step is carried out in a rotary microchannel device, which leverages the structural characteristics of the device to amplify the advantage of chemical selectivity into the advantage of physical separation. (1) Ultra-efficient mass transfer: The rotational shear force of the rotary microchannel device can disperse the two phases into micron-sized droplets or liquid films, which greatly increases the specific interphase area between the aqueous phase and the organic phase, shortens the time required for the phosphoric acid complexation reaction to reach complete equilibrium, and thus shortens the contact time between the hydrophilic phase and the organic phase; the short contact time can compress the co-extraction window period of impurities.

[0046] (2) Centrifugal force in situ phase separation: The centrifugal force generated by the rotation of the rotary microchannel device can simultaneously achieve rapid and thorough separation of the organic phase and the aqueous phase during the extraction process, greatly reducing the entrainment of the aqueous phase in the organic phase and preventing CaCl2 and metal impurities from entering the organic phase along with the aqueous phase from the source.

[0047] (3) Flow pattern control of hollow fiber membrane: The hollow fiber membrane set in the hydrophobic section of the rotary microchannel device can repeatedly divide and guide the hydrophobic encapsulated particles, prevent impurities carried by large particle encapsulations from penetrating the organic phase, and further purify the loaded organic phase.

[0048] (4) Risk management of long-chain fatty alcohol modifiers: Long-chain fatty alcohol modifiers can further reduce the viscosity of the mixed organic phase to 3 mPa·s to 10 mPa·s, and work in conjunction with the high shear force of the rotary microchannel device to enable the aqueous phase and organic phase to be completely separated in a shorter time, further reducing the amount of aqueous phase entrained in the organic phase, and further reducing the risk of metal impurities entering the organic phase with the aqueous phase microdroplets.

[0049] 4. Back-extraction for secondary purification and terminal impurity interception.

[0050] When the organic phase loaded with phosphoric acid is back-extracted with pure water, a dual purification effect occurs: (1) Chemical dissociation purification: H in the aqueous phase + As the concentration decreases sharply, the trioctylamine-phosphate complex completely dissociates, and the phosphoric acid is transferred to the aqueous phase; while a very small amount of neutral organic impurities and non-polar impurities that were co-extracted to the organic phase remain in the organic phase, achieving secondary purification. (2) Terminal solid-liquid separation and impurity removal: In the weakly acidic environment of back-extraction, trace amounts of Ca entrained in the organic phase are removed. 2+ Mg 2+ Fe 3+ Al 3+ and residual F - It combines with phosphate ions to form insoluble precipitates of dicalcium phosphate, calcium fluoride, and metal phosphates. These precipitates are fixed in the white fertilizer product after solid-liquid separation, while the aqueous phase yields clear, high-purity industrial-grade phosphoric acid.

[0051] 5. The entire process is closed-loop with no external contamination.

[0052] The entire method uses only hydrochloric acid (acid hydrolysis) and pure water (back-extraction), without adding any additional chemical reagents such as sulfides, flocculants, or alkali neutralizers, thus avoiding the formation of sodium. + S 2- The introduction of foreign impurities is prevented; the composite extractant can be recycled after washing and regeneration, eliminating the risk of impurity accumulation and ensuring the long-term purity and stability of phosphoric acid products.

[0053] II. Mechanisms for Improving Phosphate Rock Utilization 1. Pre-extraction protects the main extraction system: ensuring long-term stable operation.

[0054] The first pre-extraction of tributyl phosphate not only removes impurities, but more importantly, protects the subsequent ternary composite extractant and the rotary microchannel equipment. (1) Remove impurities such as fluorosilicic acid in advance. If fluorosilicic acid enters the main extraction system, it will form an irreversible complex with amine extractants, leading to deactivation of the extractants and blockage of the hydrophobic section of the microchannel. (2) Pre-extraction extends the service life of the composite extractant, ensuring that the rotary microchannel can operate for a long time, avoiding frequent shutdowns and regeneration due to impurity accumulation, thereby maintaining the continuous and efficient recovery of phosphorus from phosphate rock.

[0055] 2. Full productization of phosphorus resources: cascade utilization of phosphoric acid → dicalcium phosphate → calcium phosphate.

[0056] In traditional processes, the dicalcium phosphate (white fertilizer) obtained from back-extraction is often treated as a low-value byproduct or solid waste, while industrial-grade phosphoric acid is sold directly. This method involves sequentially neutralizing and adjusting the pH of a portion of the industrial-grade phosphoric acid with the dicalcium phosphate product to prepare high-value-added calcium phosphate products (such as tricalcium phosphate, hydroxyapatite, etc.). (1) Internal circulation of calcium and phosphorus: The calcium in dicalcium phosphate and the phosphorus in industrial grade phosphoric acid are combined twice within the system, eliminating the need to purchase phosphorus or calcium sources externally, thus achieving full coverage of phosphorus resources in product form. (2) Product diversification: The same production system can produce three phosphorus products: industrial-grade phosphoric acid, dicalcium phosphate, and calcium phosphate. The output ratio can be flexibly adjusted according to market demand to enhance the economic value of phosphate rock.

[0057] 3. Calcium resource recovery: commercialization of calcium chloride products.

[0058] The calcium-containing aqueous phase (mainly CaCl2) generated during the extraction stage is not discharged as wastewater. Instead, it is precipitated, filtered, and concentrated to prepare calcium chloride products (liquid ≥15% or solid ≥90% purity, metal impurities ≤0.1%). The CaCl2 generated by hydrochloric acid hydrolysis is completely soluble in water. This method, through an extraction-phase separation-aqueous phase concentration process, converts all the calcium elements in the phosphate rock into marketable products, avoiding the loss of calcium resources.

[0059] 4. Metal resource recovery: metal oxide concentrate.

[0060] In traditional processes, metallic impurities such as Fe, Mg, and Al in phosphate rock are either lost with waste residue or contaminate phosphoric acid products. This method achieves metal resource recovery through a three-stage interception process: (1) Interception during acid hydrolysis filtration stage: During the filtration stage of acid hydrolysis slurry, a filter screen can be used to separate the metal oxides that have not participated in the acid hydrolysis reaction, forming slag; the slag can be subsequently separated by magnetic separation or used directly as building material.

[0061] (2) Chemical-physical double-lock interception in the extraction stage: The long-chain fatty alcohol modifier in the composite extractant inhibits the chemical co-extraction of metal complex anions and enhances the physical effect of centrifugal phase separation, so that the metal ions are retained to the maximum extent in the raffinate (calcium-containing aqueous phase), reducing the proportion of metal in phosphate rock entering the organic phase, thereby significantly improving the metal concentration in the calcium-containing aqueous phase and the subsequent precipitation recovery rate.

[0062] (3) Precipitation process of calcium-containing aqueous phase: The pH value of the calcium-containing aqueous phase is adjusted to 9-10, so that the soluble metal chlorides in the calcium-containing aqueous phase form hydroxide precipitates, which are then output in the form of mixed precipitates. The mixed precipitates {Fe(OH)3, Al(OH)3, Mg(OH)2, etc.} are calcined at 400℃ to 800℃ and dehydrated into metal oxide concentrates (Fe2O3, Al2O3, MgO, etc.), which can be sold as ceramic raw materials, water purification agent precursors or metallurgical auxiliary materials, realizing zero waste and full value utilization of metal oxide impurities in phosphate rock.

[0063] (4) Back-extraction precipitation process: Trace amounts of metal phosphates in the loaded organic phase can enter the dicalcium phosphate product during the solid-liquid separation stage of back-extraction, and then enter the calcium phosphate product through the neutralization reaction of the dicalcium phosphate product or be collected separately.

[0064] 5. Zero waste design throughout the entire process and high comprehensive phosphorus recovery rate.

[0065] This method incorporates all elements such as P, Ca, Fe, Mg, Al, and F from phosphate rock into its product system through a product matrix consisting of "phosphate products + dicalcium phosphate + calcium phosphate + calcium chloride + metal oxide concentrate". (1) Phosphorus: distributed in phosphoric acid, dicalcium phosphate, calcium phosphate, and calcium chloride (trace amount); (2) Calcium: distributed in calcium phosphate and calcium chloride; (3) Metallic elements: enriched in metal oxide concentrates; (4) Fluorine: It is fixed and removed in the form of CaF2, fluorosilicic acid, etc. during the pre-extraction and back-extraction stages.

[0066] The method can achieve a comprehensive phosphorus recovery rate of over 90% (phosphoric acid product yield ≥84%, with phosphorus distributed in phosphoric acid, white fertilizer, and calcium phosphate products), and no hazardous waste is generated throughout the process, fundamentally solving the problems of "low phosphorus utilization and difficulty in solid waste storage" that exist in traditional wet phosphoric acid production.

[0067] In summary, the present application provides a method for preparing phosphate from phosphate rock based on hydrochloric acid decomposition. This method achieves six-level gradient removal of impurities such as fluorine, metal ions, and chloride ions in terms of purity through the synergistic effects of pre-extraction and pre-purification, gradient synergistic extraction, microchannel enhanced phase separation, back-extraction secondary purification, terminal solid-liquid separation, and full element resource utilization. Furthermore, by using long-chain fatty alcohol modifiers to inhibit the steric hindrance of metal complex anions and repel water molecules at the interface, the method achieves the directional retention of metal impurities during the extraction stage, enabling the purity of industrial-grade phosphoric acid to reach approximately 90%. In terms of utilization, the method achieves the full resource utilization and productization of phosphorus, calcium, and metals, resulting in a comprehensive phosphorus recovery rate of over 90% in phosphate rock, realizing the full utilization of phosphate rock and turning waste into treasure.

[0068] In some alternative embodiments, the mixed organic phase comprises, by mass fraction of the composite extractant: trioctylamine: 20% to 35%, tributyl phosphate: 10% to 25%, triethylamine: 5% to 15%, and long-chain fatty alcohol modifier: 2% to 8%.

[0069] In these embodiments, with the composite extractant having a mass fraction of 100%, the mixed organic phase designed with a gradient ratio ensures both a high extraction yield of phosphoric acid and maximizes the suppression of impurity co-extraction, which is the core of improving the purity of phosphoric acid. The specific mechanism is as follows: A trioctylamine concentration of 20% to 35% by mass provides sufficient protonation sites, ensuring a high single-stage extraction rate of phosphoric acid and avoiding product yield loss due to insufficient trioctylamine as the primary extractant. Simultaneously, it avoids the problems of excessively low polarity and increased viscosity in the mixed organic phase caused by excessive long-chain tertiary amines, thereby reducing the non-specific co-extraction of metal impurities and fluorine by the primary extractant and fundamentally reducing the load of impurities entering the mixed organic phase.

[0070] Tributyl phosphate at a mass fraction of 10% to 25% can form a significant synergistic extraction effect with trioctylamine. Through the complementary formation of hydrogen bonds between the P=O bond of tributyl phosphate and the -OH group of phosphate, hydrogen bonds can be formed, which can supplement the extraction sites of phosphate and further improve the extraction completeness of the mixed organic phase. At the same time, tributyl phosphate can precisely adjust the polarity of the mixed organic phase, avoiding the precipitation of amine phosphate complexes formed between the mixed organic phase and phosphate, which would otherwise form a third phase that would disrupt the extraction process. In addition, controlling the mass fraction of tributyl phosphate can avoid the co-extraction problem of hydrochloric acid and chloride ions caused by excessive tributyl phosphate, thus ensuring the selective separation of phosphate and impurities.

[0071] Triethylamine at a mass fraction of 5% to 15% can supplement the active extraction sites of the composite extractant, accelerate the extraction reaction rate, and adjust the polarity of the organic phase interface to further enhance the targeted binding ability of phosphoric acid. At the same time, strictly controlling the mass fraction of triethylamine can avoid the inherent defects of short-chain tertiary amines, such as high water solubility, easy entrainment of aqueous phase impurities, and high volatility, thereby improving the completeness of extraction without reducing the separation selectivity.

[0072] Long-chain fatty alcohol modifiers with a mass fraction of 2% to 8% can preferentially occupy the active site of the amine salt by forming hydrogen bonds with the amino group of protonated trioctylamine through hydroxyl groups, thus hindering the modification of [FeCl4]. - [AlCl4] - The interfacial mass transfer channels facilitate the migration of metal complex anions into the organic phase, thereby directionally locking metal ions such as Fe, Al, and Mg in the aqueous phase (raffinate), maximizing the recovery rate of subsequent metal oxide concentrates. Simultaneously, the introduction of long-chain fatty alcohols can precisely reduce the viscosity of the mixed organic phase to the range of 3 mPa·s to 10 mPa·s, improving the flowability of the organic phase in the rotating microchannel. This, combined with rotational shear force, enhances the centrifugal phase separation effect between the two phases, further reducing the amount of aqueous microdroplets entrained in the organic phase. Furthermore, controlling the mass fraction of long-chain fatty alcohols avoids excessive introduction leading to an excessive increase in the polarity of the organic phase, which weakens the selective complexing ability of trioctylamine for phosphate. It also avoids the risk of impurity entrainment caused by increased water solubility and excessive interfacial emulsification of long-chain fatty alcohol modifiers when the carbon chain is too short or the content is too high. This achieves a simultaneous improvement in metal impurity rejection rate and phase separation efficiency without reducing the phosphate extraction rate.

[0073] The mass fraction of the trioctylamine can be 20%, 21%, 22%, 23%, 24%, 25%, 30%, or 35%.

[0074] The mass fraction of the tributyl phosphate can be 10%, 11%, 12%, 13%, 14%, 15%, 20%, or 25%.

[0075] The mass fraction of the triethylamine can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%.

[0076] The mass fraction of the long-chain fatty alcohol modifier can be 2%, 3%, 4%, 5%, 6%, 7%, or 8%.

[0077] It should be noted that the composition of the mixed organic phase, including trioctylamine, tributyl phosphate, triethylamine, and long-chain fatty alcohol modifiers, is highly compatible with the microchannel characteristics of the rotary microchannel device, completely solving the problems of flow pattern disorder, clogging, and incomplete phase separation inherent in traditional extraction. Specifically: (1) Precise control of physical properties to adapt to the microchannel flow pattern requirements of rotary microchannel equipment: The synergistic effect between trioctylamine, tributyl phosphate and triethylamine can stabilize the viscosity of the mixed organic phase within the optimal viscosity range of microchannel flow from 5 mPa·s to 15 mPa·s, so that the mixed organic phase has excellent flowability and completely avoids problems such as microchannel blockage and flow pattern disorder caused by high viscosity mixed organic phase; at the same time, triethylamine in the mixed organic phase can precisely adjust the interfacial tension of the mixed organic phase, so that the mixed organic phase in the rotary microchannel forms a uniform and stable micron-level slug flow or droplet flow under the action of shear force, and the specific phase area is greatly increased to improve the mass transfer efficiency in the extraction stage, so that the extraction equilibrium time is fully adapted to the short residence time of the microchannel. Furthermore, the addition of long-chain fatty alcohol modifiers can further optimize the viscosity of the mixed organic phase to a lower range of 3 mPa·s to 10 mPa·s. The hydrogen bonding between the hydroxyl groups of the long-chain fatty alcohol modifiers and the protonated trioctylamine, in conjunction with triethylamine, precisely regulates the interfacial tension, enabling the mixed organic phase in the rotating microchannel to form a more uniform and stable micron-scale slug flow or droplet flow under shear force, further increasing the specific phase area. At the same time, the long-chain fatty alcohol modifiers can form a water molecule repulsion layer at the interface, which can hinder the migration of metal complex anions to the organic phase, reduce the initial deposition of metal impurities on the microchannel wall, and prevent flow pattern disturbance and blockage from the source.

[0078] (2) Enhance the centrifugal phase separation effect and eliminate impurity entrainment: The rotary microchannel device relies on centrifugal force to achieve in-situ phase separation. In this mixed organic phase, tributyl phosphate can precisely control the density difference between the two phases, which shortens the phase separation time of the intermediate filter material and the composite extractant to a very short time. The organic phase and aqueous phase of the intermediate filter material can be completely separated within the short residence time of the microchannel. Compared with the binary system, the amount of aqueous phase entrainment in the organic phase can be greatly reduced, which fundamentally prevents soluble impurities from entering the organic phase with the aqueous phase, and further improves the separation accuracy. At the same time, the long-chain fatty alcohol modifier significantly improves the two-phase separation speed by reducing the viscosity of the organic phase and based on the phase separation kinetics principle under the centrifugal force field, which further shortens the phase separation time. In addition, the water molecule repulsion layer effect formed by the long-chain fatty alcohol modifier can further reduce the mechanical entrainment of aqueous microdroplets in the organic phase, which further reduces the amount of aqueous phase entrainment in the organic phase, fundamentally preventing soluble metal impurities from entering the organic phase with the aqueous phase, and further improving the separation accuracy and the recovery rate of metal oxide concentrate.

[0079] (3) Ensuring long-term continuous operation of microchannels: Strictly controlling the mass fraction of triethylamine avoids the problems of air blockage and flow pattern instability in microchannels caused by the high volatility of short-chain tertiary amines; at the same time, the system has strong anti-emulsification ability and will not flocculate or emulsify due to trace amounts of silica slag and colloidal impurities in the acid hydrolysate, which can realize long-term continuous operation of the rotating microchannel equipment, and can run continuously for many days. In addition, the carbon chain of the long-chain fatty alcohol modifier is relatively long and the volatility is extremely low, which will not introduce air blockage or flow pattern instability problems; the long-chain fatty alcohol modifier reduces the deposition and scaling of metal hydroxides or phosphates on the wall surface of the rotating microchannel equipment and the hollow fiber membrane surface by inhibiting the co-extraction of metal complex anions, thus ensuring the permeability and flow pattern stability of the hydrophobic section, thereby achieving long-term continuous operation of the rotating microchannel equipment together with triethylamine.

[0080] In some alternative embodiments, the composite extractant further includes sulfonated kerosene, wherein the sulfonated kerosene has a mass fraction of 35% to 55%.

[0081] In these embodiments, sulfonated kerosene is introduced into the composite extractant, and the mass fraction of sulfonated kerosene is controlled to be 35% to 55%. The sulfonated kerosene can fully disperse the trioctylamine, tributyl phosphate, triethylamine, and long-chain fatty alcohol modifiers in the mixed organic phase. This facilitates thorough mixing of the mixed organic phase of the composite extractant with the intermediate filter material in the rotary microchannel device, allowing for complete extraction and improving the extraction effect. At the same time, the uniformly dispersed long-chain fatty alcohol modifier can effectively inhibit soluble metal impurities from entering the organic phase with the aqueous phase, improving the recovery rate of metal oxide concentrate and thus increasing the utilization of phosphate rock.

[0082] The mass fraction of the sulfonated kerosene can be 35%, 36%, 37%, 38%, 39%, 40%, 45%, 46%, 47%, 48%, 49%, 50%, or 55%.

[0083] It should be noted that the composite extractant can be washed with ultrapure water after extraction, and then regenerated through impurity removal treatment (such as membrane separation methods like ultrafiltration membrane).

[0084] In some optional embodiments, the volume V1 of the composite extractant and the volume V2 of the intermediate filter material satisfy: V1:V2=1:(6 to 10).

[0085] In these embodiments, the composite extractant and intermediate filter media with a volume ratio of 1:(3 to 10) can be thoroughly mixed in a rotary microchannel device, which is beneficial for improving the extraction effect and ensuring that the phosphoric acid in the intermediate filter media completely enters the organic phase, thereby improving the purity of the phosphoric acid obtained from subsequent back-extraction. Simultaneously, the long-chain fatty alcohol modifier in the composite extractant can effectively inhibit soluble metal impurities from entering the organic phase with the aqueous phase, improving the recovery rate of metal oxide concentrate and thus increasing the utilization rate of phosphate rock.

[0086] The volume V2 of the intermediate filter media can be 6, 7, 8, 9 or 10.

[0087] In some alternative embodiments, the volume V3 of the water and the volume V4 of the supported organic phase satisfy: V3:V4 = (3 to 10):1; and / or The back-extraction is performed 2 to 4 times.

[0088] In these embodiments, a water-to-supported organic phase volume ratio of (3 to 10):1 ensures sufficient water in the back-extraction stage. This large volume of water disrupts the stable equilibrium of the amine-phosphate complex in the supported organic phase, causing phosphoric acid to transfer from the organic phase to the pure aqueous phase, thus achieving secondary purification of phosphoric acid. Furthermore, back-extraction two to four times allows for the staged addition of water, which is beneficial for fully disrupting the stable equilibrium of the amine-phosphate complex in the supported organic phase, thereby achieving secondary purification of phosphoric acid.

[0089] The volume V3 of the water can be 3, 4, 5, 6, 7, 8, 9 or 10.

[0090] The back-extraction can be performed 2, 3, or 4 times.

[0091] It should be noted that the volume of water used and the number of back-extractions are mainly determined by the composition of the mixed organic phase. In addition, the back-extraction of pure water has the following advantages: (1) The trioctylamine, which plays the main role in the extraction of the mixed organic phase, is highly sensitive to pH value. The organic phase loaded with amine phosphate complex can break the complexation equilibrium with only pure water, so that the single-stage back-extraction rate of phosphate is as high as 99% or more. No additional reagents such as alkali or neutralizing agent are needed, which avoids the contamination of phosphate products by impurities in these reagents from the source and ensures the purity of phosphate products. Furthermore, the addition of long-chain fatty alcohol modifiers can further optimize the viscosity of the mixed organic phase to a lower range of 3 mPa·s to 10 mPa·s. At the same time, through the hydrogen bonding between the hydroxyl groups of the long-chain fatty alcohol modifiers and protonated trioctylamine, triethylamine can be used to precisely regulate the interfacial tension, enabling the mixed organic phase in the rotating microchannel device to form a more uniform and stable micron-scale slug flow or droplet flow under shear force, further increasing the specific phase area. Meanwhile, the water molecule repulsion layer formed at the interface by the long-chain fatty alcohol modifiers can hinder the migration of metal complex anions to the organic phase, reducing the initial deposition of metal impurities on the microchannel wall and preventing flow pattern disturbance and blockage from the source.

[0092] (2) In addition, trace amounts of Ca are produced during the back-extraction process. 2+ Impurities such as metallic impurities and residual fluorine enter the aqueous phase. In the weakly acidic environment of back-extraction, these impurities combine with phosphate ions to form insoluble precipitates such as dicalcium phosphate and calcium fluoride, which can completely fix the trace impurities remaining in the loaded organic phase. High-purity industrial-grade phosphoric acid can be obtained through simple solid-liquid separation, while simultaneously achieving deep defluorination of phosphate rock and solving the problem of excessive fluorine in wet-process phosphoric acid. Furthermore, long-chain fatty alcohol modifiers significantly improve the separation rate of the two phases by reducing the viscosity of the organic phase and based on the phase separation kinetics principle under centrifugal force, further shortening the phase separation time. Moreover, the interfacial water molecule repulsion layer effect of the long-chain fatty alcohol modifiers can further reduce the mechanical entrainment of aqueous microdroplets in the organic phase, reducing the amount of aqueous entrainment in the organic phase by 30% to 50%, fundamentally preventing soluble metallic impurities from entering the organic phase with the aqueous phase, further improving separation accuracy and the recovery rate of metal oxide concentrates.

[0093] (3) In addition, the dicalcium phosphate precipitate formed during the back-extraction process has high purity and can be directly used as a feed-grade or fertilizer-grade white fertilizer product. No hazardous waste is generated, realizing the resource utilization of impurities in phosphate rock and further improving the overall economic efficiency of the method. In addition, the long-chain fatty alcohol modifier has a long carbon chain and extremely low volatility, which will not introduce air clogging or flow pattern instability problems. The long-chain fatty alcohol modifier reduces the deposition and scaling of metal hydroxides or phosphates on the microchannel wall and hollow fiber membrane surface by inhibiting the co-extraction of metal complex anions, ensuring the permeability and flow pattern stability of the hydrophobic section, thereby achieving long-term continuous operation of the rotating microchannel equipment together with triethylamine.

[0094] In some optional embodiments, the acidolysis reaction is carried out at a temperature of 25°C to 30°C for a duration of 20 min to 30 min; and / or The target particle size for filtration is 0.5 mm to 1.5 mm.

[0095] In these embodiments, the acidolysis reaction at a temperature of 25°C to 30°C and a time of 20 to 30 minutes allows for a thorough acidolysis reaction between hydrochloric acid and phosphate rock slurry, forming an acidolysis slurry rich in phosphate ions. Furthermore, filtration with a target particle size of 0.5 mm to 1.5 mm separates large, insoluble particles from the acidolysis slurry, ultimately yielding a relatively pure intermediate filter media. This facilitates subsequent extraction with the composite extractant, significantly improving the extraction efficiency.

[0096] The acidolysis reaction can be performed at temperatures of 25°C, 26°C, 27°C, 28°C, 29°C, or 30°C.

[0097] The acidolysis reaction can be performed for 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27 min, 28 min, 29 min, or 30 min.

[0098] The target particle size for filtration can be 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm or 1.5mm.

[0099] In some alternative embodiments, the gap between the microchannels in the rotary microchannel device is 1.0 mm to 3.0 mm.

[0100] In these embodiments, the microchannels with a gap of 1.0 mm to 3.0 mm in the rotary microchannel device allow sufficient space for mixing between the intermediate filter material and the composite extractant. Simultaneously, the rotational shear force of the rotary microchannel device, in conjunction with the microchannels, disperses the aqueous and organic phases into micron-sized droplets or liquid films, significantly increasing the specific interphase area between the aqueous and organic phases. This shortens the time required for the phosphate complexation reaction to reach complete equilibrium, thereby reducing the contact time between the hydrophilic and organic phases and improving the extraction efficiency. Furthermore, it ensures the inhibitory effect of the long-chain fatty alcohol modifier in the composite extractant on soluble metals, preventing soluble metal impurities from entering the organic phase with the aqueous phase, further improving separation precision and the recovery rate of metal oxide concentrates.

[0101] The gap between the microchannels in this rotary microchannel device can be 1.0mm, 1.5mm, 2.0mm, 2.5mm or 3.0mm.

[0102] In some optional embodiments, the hollow fiber membrane has a pore size of 50 nm to 80 nm; and / or The thickness of the hollow fiber membrane is 2 mm to 5 mm.

[0103] In these embodiments, hollow fiber membranes with pore sizes of 50 nm to 80 nm and thicknesses of 2 mm to 5 mm can effectively regulate the flow pattern between the intermediate filter material and the composite extractant, thereby repeatedly dividing and guiding the hydrophobic encapsulated particles, preventing impurities carried by large particle encapsulations from penetrating the organic phase, further purifying the loaded organic phase, and improving the extraction effect of the composite extractant.

[0104] The pore size of the hollow fiber membrane can be 50nm, 51nm, 52nm, 53nm, 54nm, 55nm, 60nm, 65nm, 70nm, 75nm or 80nm.

[0105] The thickness of the hollow fiber membrane can be 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm or 5mm.

[0106] In some optional embodiments, the volume V5 of the first tributyl phosphate and the volume V2 of the intermediate filter media satisfy: V5:V2 = 1:(8 to 15); and / or The mass m1 of the industrial-grade phosphoric acid and the mass m2 of the dicalcium phosphate product satisfy: m1:m2 = (1 to 3):(5 to 10); and / or The mass of the industrial-grade phosphoric acid is 30% to 70% of the total mass of the industrial-grade phosphoric acid.

[0107] In these embodiments, a tributyl phosphate at a volume ratio of 1:(8 to 15) to the intermediate filter media can remove impurities such as fluorosilicic acid from the intermediate filter media in advance, preventing these impurities from forming irreversible complexes with amine extractants, ensuring the activity of the composite extractant, and maintaining continuous and efficient recovery of phosphorus from phosphate rock. Additionally, a portion of industrial-grade phosphoric acid at a mass ratio of (1 to 3):(5 to 10) to the dicalcium phosphate product allows the neutralization reaction to proceed fully, forming a high-value calcium phosphate product. Furthermore, a portion of industrial-grade phosphoric acid, comprising 30% to 70% of the total mass of industrial-grade phosphoric acid, allows the neutralization reaction to proceed fully without affecting the yield of phosphoric acid products, achieving full recovery of phosphorus from phosphate rock.

[0108] The volume V2 of the intermediate filter media can be 8, 9, 10, 11, 12, 13, 14 or 15.

[0109] The mass m1 of this industrial-grade phosphoric acid can be 1, 1.1, 1.2, 1.3, 1.4, 1.5, 2.0, 2.5 or 3.0.

[0110] The mass m2 of this dicalcium phosphate product can be 5, 6, 7, 8, 9 or 10.

[0111] The mass of this portion of industrial-grade phosphoric acid can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, or 70% of the total mass of industrial-grade phosphoric acid.

[0112] In some optional embodiments, the neutralization reaction is carried out at a temperature of 40°C to 80°C for a duration of 30 min to 120 min; and / or The calcination temperature is 400℃ to 800℃, and the calcination time is 1h to 4h.

[0113] In these embodiments, a neutralization reaction at a temperature of 40°C to 80°C and a time of 30 min to 120 min allows for a sufficient reaction between some of the industrial-grade phosphoric acid and dicalcium phosphate products, via the H+ ionization of phosphoric acid. + The hydrogen phosphate ions of calcium phosphate react fully with those of dicalcium phosphate to form a large amount of calcium phosphate product. In addition, calcination at a temperature of 400°C to 800°C for 1 to 4 hours can cause the mixed precipitate containing metal hydroxides to form a high-purity metal oxide concentrate under high-temperature conditions.

[0114] The temperature for the neutralization reaction can be 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃.

[0115] The neutralization reaction time can be 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, or 120 min.

[0116] The calcination temperature can be 400℃, 450℃, 500℃, 550℃, 600℃, 650℃, 700℃, 750℃ or 800℃.

[0117] The calcination time can be 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, or 4 hours.

[0118] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national / industry standards; if there is no corresponding national / industry standard, they are performed according to general international standards, conventional conditions, or conditions recommended by the manufacturer.

[0119] Example 1

[0120] A method for preparing phosphate based on hydrochloric acid decomposition of phosphate rock, wherein the phosphate rock comprises metal oxides and calcium, comprising: S1. The phosphate rock is pulped to obtain phosphate slurry; the specific process is as follows: Phosphate ore (with a phosphorus mass fraction of more than 5%) is crushed by a crusher, and then deionized water is added for grinding and pulping to obtain phosphate ore slurry (with a phosphorus mass fraction of more than 1.5%). S2. The phosphate rock slurry is acid-hydrolyzed using hydrochloric acid to obtain an acid-hydrolyzed slurry; the specific process is as follows: Phosphate rock slurry is introduced into a phosphoric acid reaction tank, and then hydrochloric acid with a mass concentration of 26% is added and mixed. The material in the phosphoric acid reaction tank is then introduced into an intermediate tank for acid hydrolysis. After the reaction is completed, the acid hydrolysate in the phosphoric acid reaction tank is introduced into the next process. S3. Filter the acid-hydrolyzed slurry to obtain intermediate filter material; the specific process is as follows: In a filter containing a filter screen with a pore size of 1.0 mm, the acid hydrolysate is repeatedly filtered three times to obtain intermediate filter material and filter residue; the filter residue can be transported out and used as building material. S4. Pre-extract the intermediate filter media using tributyl phosphate to obtain pre-extracted filter media; the specific process is as follows: Tributyl phosphate and intermediate filter media are fed into a pre-extraction mixing tank via a feed pump and stirred at 150 r / min for 15 min at room temperature, followed by standing for phase separation for 20 min; the pre-extraction organic phase loaded with fluorosilicic acid and trace metal complexes and the pre-extraction filter media are obtained; the pre-extraction filter media is exported to the next process, and the pre-extraction organic phase is recycled or centrally treated after alkaline washing and regeneration. S5. Extract the pre-extraction filter material using a composite extractant to obtain a calcium-containing aqueous phase and a supported organic phase; the specific process is as follows: The composite extractant and pre-extraction filter material are premixed in a mixing tank and then pumped into a rotary microchannel device through the corresponding inlet. The rotation speed of the rotary microchannel device is controlled at 500 r / min. The shear force generated by the rotation disperses the composite extractant and pre-extraction filter material into micron-sized droplets or liquid films for extraction. In the hydrophobic section, the hollow fiber membrane repeatedly divides and guides the hydrophobic particles. After extraction, the organic phase and the aqueous phase are rapidly separated in situ under centrifugal force. The phosphoric acid-loaded organic phase is discharged from the upper outlet, and the calcium-containing aqueous phase is discharged from the lower outlet. S6. Back-extraction of the supported organic phase using water yields dicalcium phosphate and industrial-grade phosphoric acid; the specific process is as follows: The loaded organic phase was pumped into a back-extraction reactor, deionized water was added, and back-extraction was performed at a stirring speed of 250 r / min and room temperature. The back-extraction was repeated three times. After each back-extraction, the phases were separated by standing, and the aqueous phase was collected. During the back-extraction process, trace amounts of Ca were entrained. 2+ Mg 2+ Fe 3+ Al 3+ and residual F - In a weakly acidic environment, it combines with phosphate to form insoluble dicalcium phosphate, calcium fluoride, and metal phosphate precipitates; in the later stage of back-extraction, a filter screen is introduced for solid-liquid separation, the filter cake is washed and dried to obtain dicalcium phosphate product (white fertilizer), and the filtrate is purified to obtain industrial grade phosphoric acid. S7. A portion of industrial-grade phosphoric acid and dicalcium phosphate products are sequentially neutralized and their pH adjusted to obtain calcium phosphate product; the specific process is as follows: A portion of industrial-grade phosphoric acid and dicalcium phosphate were added to a neutralization reaction vessel, and deionized water was added to prepare a slurry. The neutralization reaction was carried out under a stirring speed of 200 r / min. During the neutralization reaction, the pH of the system was adjusted to 6.5 to 8.5 by adding ammonia or calcium hydroxide emulsion dropwise, so that a portion of the industrial-grade phosphoric acid and dicalcium phosphate reacted fully to form calcium phosphate. After the neutralization reaction was completed, the mixture was filtered, washed, and dried to obtain the calcium phosphate product. S8. The calcium-containing aqueous phase is subjected to precipitation and filtration sequentially to obtain calcium chloride filtrate and mixed precipitate; the specific process is as follows: First, a 25% (w / w) calcium carbonate suspension was added to the calcium-containing aqueous phase to adjust the pH to approximately 4. Then, a calcium hydroxide emulsion was added to adjust the pH to 9-10. The mixture was reacted for 30 minutes under stirring to allow the Fe content in the calcium-containing aqueous phase to increase. 3+ Al 3+ Mg 2+ Once the metal ions are completely converted into hydroxide precipitates, a precipitate mixture is formed. The precipitate mixture is then subjected to pressure filtration or vacuum filtration to obtain calcium chloride filtrate and mixed precipitate. The mixed precipitate is then washed 2 to 3 times with deionized water, and the washing liquid is reused in the acidolysis or pulping process. S9. Concentrate the calcium chloride filtrate to obtain the calcium chloride product; the specific process is as follows: The calcium chloride filtrate is introduced into an evaporation and concentration device and concentrated under reduced pressure at 100°C. When the calcium chloride mass concentration in the solution reaches more than 15%, the concentrate can be directly packaged as a liquid calcium chloride product; or it can be further evaporated, crystallized, centrifuged, and dried to obtain a solid calcium chloride product with a purity of about 90%. S10. The mixed precipitate is calcined to obtain a metal oxide concentrate; the specific process is as follows: The washed mixed precipitate is placed in a calcining furnace for calcination, so that the hydroxides in the mixed precipitate are completely dehydrated and transformed into stable metal oxides. After natural cooling or forced cooling, it is crushed and screened to obtain metal oxide concentrate (mainly containing Fe2O3, Al2O3, MgO, etc.), which can be used as ceramic raw material, water purification agent precursor or metallurgical auxiliary material. The extraction is carried out in a rotary microchannel device, which includes a hollow fiber membrane located in the hydrophobic section of the rotary device. The composite extractant includes a mixed organic phase of triethylamine, tributyl phosphate, and trioctylamine, wherein the mass fraction of trioctylamine is greater than the mass fraction of tributyl phosphate and greater than the mass fraction of triethylamine.

[0121] The mixed organic phase, by mass fraction of the composite extractant, includes: trioctylamine: 25%, tributyl phosphate: 10%, triethylamine: 10%, and long-chain fatty alcohol modifier (n-octanol): 5%.

[0122] The compound extractant also includes sulfonated kerosene, with a mass fraction of 50%.

[0123] The volume V1 of the composite extractant and the volume V2 of the intermediate filter media satisfy the following: V1:V2=1:8; The volume of water, V3, and the volume of the supported organic phase, V4, satisfy the following ratio: V3:V4 = 7:1; The number of back-extractions was 3.

[0124] The acid hydrolysis reaction was carried out at a temperature of 25℃ for 25 minutes. The target particle size for filtration is 1.0 mm.

[0125] The gap between the microchannels in the rotary microchannel device is 2.0 mm.

[0126] The hollow fiber membrane has a pore size of 70 nm; The thickness of the hollow fiber membrane is 4 mm.

[0127] The volume V5 of the first tributyl phosphate and the volume V2 of the intermediate filter material satisfy the following ratio: V5:V2=1:10; The mass m1 of a portion of industrial-grade phosphoric acid and the mass m2 of dicalcium phosphate product satisfy the following ratio: m1:m2=2:7; The mass of some industrial-grade phosphoric acid is 40% of the total mass of industrial-grade phosphoric acid.

[0128] The neutralization reaction was carried out at a temperature of 60℃ for 80 minutes. The calcination temperature was 600℃ and the calcination time was 3 hours.

[0129] Example 2

[0130] Compared to Example 1, the differences in this example are as follows, and corresponding modifications have been made; all other aspects remain the same: The mixed organic phase, by mass fraction of the composite extractant, includes: trioctylamine: 20%, tributyl phosphate: 12%, triethylamine: 5%, and long-chain fatty alcohol modifier: 8%.

[0131] The compound extractant also includes sulfonated kerosene, which has a mass fraction of 55%.

[0132] The volume V1 of the composite extractant and the volume V2 of the intermediate filter media satisfy the following ratio: V1:V2=1:6; The volume of water, V3, and the volume of the supported organic phase, V4, satisfy the following ratio: V3:V4 = 5:1.

[0133] The acid hydrolysis reaction was carried out at a temperature of 30℃ for 20 minutes. The target particle size for filtration is 0.5 mm.

[0134] The gap between the microchannels in the rotary microchannel device is 1.0 mm.

[0135] The hollow fiber membrane has a pore size of 50 nm; The thickness of the hollow fiber membrane is 2 mm.

[0136] The volume V5 of the first tributyl phosphate and the volume V2 of the intermediate filter material satisfy the following: V5:V2=1:9; The mass m1 of a portion of industrial-grade phosphoric acid and the mass m2 of dicalcium phosphate product satisfy the following ratio: m1:m2 = 2.5:7.5; The mass of industrial-grade phosphoric acid is 30% of the total mass of industrial-grade phosphoric acid.

[0137] The neutralization reaction was carried out at a temperature of 50℃ for 60 minutes. The calcination temperature was 500℃ and the calcination time was 4 hours.

[0138] Example 3

[0139] Compared to Example 1, the differences in this example are as follows, and corresponding modifications have been made; all other aspects remain the same: The mixed organic phase, by mass fraction of the composite extractant, includes: trioctylamine: 30%, tributyl phosphate: 15%, triethylamine: 15%, and long-chain fatty alcohol modifier: 5%.

[0140] The compound extractant also includes sulfonated kerosene, which has a mass fraction of 35%.

[0141] The volume V1 of the composite extractant and the volume V2 of the intermediate filter media satisfy the following ratio: V1:V2=1:10; The volume of water, V3, and the volume of the supported organic phase, V4, satisfy the following ratio: V3:V4 = 9:1; The number of back-extractions was 3.

[0142] The acid hydrolysis reaction was carried out at a temperature of 27℃ for 30 minutes. The target particle size for filtration is 1.5 mm.

[0143] The gap between the microchannels in the rotary microchannel device is 3.0 mm.

[0144] The hollow fiber membrane has a pore size of 80 nm; The thickness of the hollow fiber membrane is 5 mm.

[0145] The volume V5 of the first tributyl phosphate and the volume V2 of the intermediate filter material satisfy the following ratio: V5:V2=1:12; The mass m1 of a portion of industrial-grade phosphoric acid and the mass m2 of dicalcium phosphate product satisfy the following ratio: m1:m2=3:9; The mass of industrial-grade phosphoric acid is 60% of the total mass of industrial-grade phosphoric acid.

[0146] The neutralization reaction was carried out at a temperature of 40℃ for 120 minutes. The calcination temperature was 800℃ and the calcination time was 1 hour.

[0147] Comparative Example 1 Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same: Trioctylamine is not added to the mixed organic phase. That is, based on the mass fraction of the composite extractant, the mixed organic phase includes: tributyl phosphate: 35%, triethylamine: 10%, and long-chain fatty alcohol modifier: 5%.

[0148] The sulfonated kerosene has a mass fraction of 50%.

[0149] Comparative Example 2 Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same: Tributyl phosphate is not added to the mixed organic phase. That is, based on the mass fraction of the composite extractant, the mixed organic phase includes: trioctylamine: 35%, triethylamine: 10%, and long-chain fatty alcohol modifier: 5%.

[0150] The sulfonated kerosene has a mass fraction of 50%.

[0151] Comparative Example 3 Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same: Triethylamine is not added to the mixed organic phase. That is, based on the mass fraction of the composite extractant, the mixed organic phase includes: trioctylamine: 25%, tributyl phosphate: 20%, and long-chain fatty alcohol modifier: 5%.

[0152] The sulfonated kerosene has a mass fraction of 50%.

[0153] Comparative Example 4 Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same: No long-chain fatty alcohol modifiers are added to the mixed organic phase. That is, based on the mass fraction of the composite extractant, the mixed organic phase includes: trioctylamine: 25%, tributyl phosphate: 15%, and triethylamine: 10%.

[0154] The sulfonated kerosene has a mass fraction of 50%.

[0155] Comparative Example 5 Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same: The extraction process does not use a mixed organic phase; instead, trioctylamine is used directly to replace the mixed organic phase.

[0156] Comparative Example 6 Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same: The extraction process does not use rotating microchannel equipment; extraction is performed directly using an extraction tank.

[0157] Comparative Example 7 Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same: Trioctylamine is used directly to replace the mixed organic phase; and the extraction process is not carried out in a rotary microchannel device, but directly in an extraction tank.

[0158] Comparative Example 8 Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same: Instead of using tributyl phosphate for pre-extraction, the intermediate filter material is directly extracted.

[0159] Relevant experimental and effect data: Phosphoric acid products and dicalcium phosphate products (white fertilizer) obtained from each example and comparative example were collected. The purity and yield of phosphoric acid products, the yield of calcium phosphate products, the yield of metal oxide concentrates, and the overall phosphorus recovery rate of phosphate rock were statistically analyzed. The results are shown in Table 1. The overall phosphorus recovery rate of phosphate rock refers to the ratio of the mass of phosphorus in the phosphoric acid products, dicalcium phosphate products, and calcium phosphate products to the mass of phosphorus in the phosphate rock. The yields of phosphoric acid products, calcium phosphate products, and metal oxide concentrates were all calculated based on the dry basis mass of the phosphate rock.

[0160] Table 1. Purity and yield results of phosphoric acid products obtained from each example and comparative example. As shown in Table 1, the method for preparing phosphate based on hydrochloric acid decomposition of phosphate rock provided in this application achieves six-level gradient removal of impurities such as fluorine, metal ions, and chloride ions in terms of purity through the synergistic effects of pre-extraction and pre-purification, gradient synergistic extraction, microchannel enhanced phase separation, back-extraction secondary purification, terminal solid-liquid separation, and full element resource utilization. Furthermore, by using long-chain fatty alcohol modifiers to inhibit the steric hindrance of metal complex anions and repel interfacial water molecules, the method achieves directional retention of metal impurities during the extraction stage, resulting in an industrial-grade phosphoric acid purity of approximately 90%. Subsequent calcination treatment achieves full resource utilization and productization of phosphorus, calcium, and metals, resulting in a comprehensive phosphorus recovery rate of over 90% in the phosphate rock. Therefore, this method comprehensively realizes the full utilization of phosphate rock and transforms waste into treasure.

[0161] Compared to Example 1, Comparative Example 1 did not use trioctylamine, Comparative Example 2 did not use tributyl phosphate, Comparative Example 3 did not use triethylamine, and Comparative Example 4 did not use long-chain fatty alcohol modifiers. As a result, the synergistic effect of the mixed organic phase could not be achieved, which reduced the purity of the phosphoric acid product to 81% to 85% and the overall phosphorus recovery rate to 84% to 88%. This indicates that there is indeed a synergistic effect among the components in the mixed organic phase.

[0162] Compared to Example 1, Comparative Example 5 used a single trioctylamine as the mixed organic phase, which resulted in a phosphoric acid product purity of only 75% and a comprehensive phosphorus recovery rate of only 78.5%, indicating a significant synergistic effect between the composite extractants.

[0163] Compared to Example 1, Comparative Example 6 used a traditional extraction tank instead of a rotary microchannel device, which resulted in a phosphoric acid product purity of only 78% and a phosphorus recovery rate of only 81%, indicating that the rotary microchannel device has an enhanced mass transfer effect.

[0164] Compared to Example 1, Comparative Example 7 used only trioctylamine as the mixed organic phase and used a conventional extraction tank instead of a rotating microchannel device, resulting in a phosphoric acid product purity of only 65.5% and a total phosphorus recovery rate of only 70.5%. Compared to Comparative Examples 5 and 6, this demonstrates a significant synergistic effect between the composite extractant and the rotating microchannel.

[0165] Compared to Example 1, Comparative Example 8 lacked the pre-extraction of tributyl phosphate to remove impurities, resulting in a phosphoric acid product purity of only 85.8%, which is between that of the Example and the Comparative Example. This indicates that pre-extraction has a certain effect on improving the purity of phosphoric acid.

[0166] In summary, the embodiments of this application provide a method for preparing phosphate based on hydrochloric acid decomposition of phosphate rock. This method improves the purity of phosphate from three dimensions: the source, process, and end of impurity removal, through a six-level progressive mechanism of pre-extraction and pre-purification, gradient synergistic extraction, microchannel enhanced phase separation, back-extraction secondary purification, terminal solid-liquid separation, and full element resource utilization. At the same time, it maximizes the utilization of phosphate rock through the full productization of phosphorus, calcium, and metal oxides.

[0167] In addition, the embodiments of this application provide a method for preparing phosphate based on hydrochloric acid decomposition of phosphate rock. This method produces phosphoric acid by wet leaching decomposition with hydrochloric acid, without the problem of by-product solid waste from other inorganic or organic acids. At the same time, by precipitation and filtration of calcium-containing aqueous phase and calcination of mixed precipitate, the loss of phosphate rock is reduced from the source, and the environmental risks of wet leaching decomposition are greatly reduced.

[0168] Furthermore, this application provides a method for preparing phosphate based on hydrochloric acid decomposition of phosphate rock. This method can not only solve the current problem of large hydrochloric acid production and difficulty in consumption, but also produce calcium chloride, metal oxide concentrate and high-value calcium phosphate products while fully recovering phosphate rock, thereby realizing the full utilization of phosphate rock and hydrochloric acid and improving the utilization rate of phosphate rock.

[0169] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed in this application.

Claims

1. A method for preparing phosphate based on hydrochloric acid decomposition of phosphate rock, wherein the phosphate rock comprises metal oxides and calcium, characterized in that, The method includes: Phosphate ore is pulped to obtain phosphate ore slurry; The phosphate rock slurry was subjected to an acid hydrolysis reaction using hydrochloric acid to obtain an acid hydrolyzed slurry. The acid-hydrolyzed slurry is filtered to obtain intermediate filter material; The intermediate filter media was pre-extracted using tributyl phosphate to obtain pre-extracted filter media; The pre-extraction filter material was extracted using a composite extractant to obtain a calcium-containing aqueous phase and a supported organic phase. The supported organic phase was back-extracted using water to obtain dicalcium phosphate product and industrial-grade phosphoric acid. A portion of the industrial-grade phosphoric acid and the dicalcium phosphate product are sequentially subjected to neutralization reactions and pH adjustments to obtain the calcium phosphate product. The calcium-containing aqueous phase was subjected to precipitation and filtration in sequence to obtain calcium chloride filtrate and mixed precipitate; The calcium chloride filtrate was concentrated to obtain the calcium chloride product; The mixed precipitate was calcined to obtain a metal oxide concentrate. The extraction is carried out in a rotary microchannel device, which includes a hollow fiber membrane disposed in the hydrophobic section of the rotary device. The composite extractant comprises a mixed organic phase of triethylamine, tributyl phosphate, trioctylamine, and a long-chain fatty alcohol modifier, wherein the mass fraction of trioctylamine is greater than the mass fraction of tributyl phosphate and greater than the mass fraction of triethylamine.

2. The method according to claim 1, characterized in that, Based on the mass fraction of the composite extractant, the mixed organic phase comprises: trioctylamine: 20% to 35%, tributyl phosphate: 10% to 25%, triethylamine: 5% to 15%, and long-chain fatty alcohol modifier: 2% to 8%.

3. The method according to claim 1, characterized in that, The composite extractant also includes sulfonated kerosene, wherein the sulfonated kerosene has a mass fraction of 35% to 55%.

4. The method according to claim 1, characterized in that, The volume V1 of the composite extractant and the volume V2 of the intermediate filter material satisfy the following condition: V1:V2=1:(6 to 10).

5. The method according to claim 1, characterized in that, The volume V3 of the water and the volume V4 of the supported organic phase satisfy: V3:V4 = (3 to 10):1; and / or The back-extraction is performed 2 to 4 times.

6. The method according to claim 1, characterized in that, The acidolysis reaction is carried out at a temperature of 25°C to 30°C for a duration of 20 min to 30 min; and / or The target particle size for filtration is 0.5 mm to 1.5 mm.

7. The method according to claim 1, characterized in that, The gap between the microchannels in the rotary microchannel device is 1.0 mm to 3.0 mm.

8. The method according to claim 1, characterized in that, The hollow fiber membrane has a pore size of 50 nm to 80 nm; and / or The thickness of the hollow fiber membrane is 2 mm to 5 mm.

9. The method according to claim 1, characterized in that, The volume V5 of the first tributyl phosphate and the volume V2 of the intermediate filter media satisfy: V5:V2 = 1:(8 to 15); and / or The mass m1 of the industrial-grade phosphoric acid and the mass m2 of the dicalcium phosphate product satisfy: m1:m2 = (1 to 3):(5 to 10); and / or The mass of the industrial-grade phosphoric acid is 30% to 70% of the total mass of the industrial-grade phosphoric acid.

10. The method according to claim 1, characterized in that, The neutralization reaction is carried out at a temperature of 40°C to 80°C for a duration of 30 min to 120 min; and / or The calcination temperature is 400℃ to 800℃, and the calcination time is 1h to 4h.

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