A leaching agent and method for extracting interstitial phosphorus from ardealite

Abstract

The application provides a leaching agent and method for extracting eutectic phosphorus in phosphogypsum. The leaching agent for extracting eutectic phosphorus in phosphogypsum comprises an extractant and an extracting agent, eutectic phosphorus in a crystal lattice is released by the extracting agent, transferred to a water body, and then dissolved eutectic phosphorus and soluble phosphorus in the water are enriched in an organic phase by the extractant to realize separation of P and F. The method for extracting eutectic phosphorus in phosphogypsum adopts a physical + chemical combined method to promote release of eutectic phosphorus. Wet grinding is used to reshape the morphology of phosphogypsum, break the surface crystal lattice, release all soluble phosphorus and a small part of eutectic phosphorus into the water body, enrich the phosphorus in the water into the organic phase by the extractant, accelerate the release of phosphorus, and thus shorten the washing time. The wet grinding only needs one water washing to achieve the effect of traditional three water washings, greatly reducing the water consumption. Meanwhile, the wet grinding also improves the surface morphology of the phosphogypsum and enhances the flowability of the phosphogypsum, thereby reducing the water requirement when the phosphogypsum is used as building materials.

Description

Technical Field

[0001] This invention relates to the field of harmless treatment technology of phosphogypsum, and in particular to an extractant and method for extracting eutectic phosphorus from phosphogypsum. Background Technology

[0002] Phosphogypsum is a solid waste produced during the wet-process phosphoric acid production process, and its main component is SO4. 2- With Ca 2+ In the process of leaching phosphate rock with sulfuric acid, calcium sulfate precipitate is formed, and impurities such as phosphorus (P), phosphorus (F), heavy metals, and organic matter are mixed in. Indiscriminate dumping of these impurities can cause serious pollution to the surrounding soil, water, and atmosphere. Currently, my country's annual production of phosphogypsum is 80 million tons, with a utilization rate of 40 million tons per year. As of the end of 2022, my country had accumulated 870 million tons of phosphogypsum stockpiles, and this figure is still growing at a rate of approximately 40 million tons per year. Existing phosphogypsum stockpiles will be full within the next few years.

[0003] Phosphorus in phosphogypsum is classified into soluble phosphorus, eutectic phosphorus, and insoluble phosphorus. Insoluble phosphorus is mainly composed of calcium phosphate, which is chemically stable and does not cause harm during accumulation or resource utilization. Soluble phosphorus includes H3PO4 and H2PO4. - HPO4 2- PO4 3- These substances are easily transferred into water bodies, and existing methods for the harmless treatment of phosphogypsum can achieve the required standards through water washing and sedimentation. Eutectic phosphorus is composed of H₂PO₄. - HPO4 2- Replace SO 4- When it enters the calcium sulfate lattice, it exists in the form of lattice phosphorus, which is not easily soluble in water and is difficult to remove by conventional water washing and precipitation. It will be slowly released during the accumulation process, polluting the environment. During the utilization of phosphogypsum in building materials, it will hydrate and precipitate, which will seriously affect the mechanical properties of phosphogypsum-based building materials and hinder the resource utilization of phosphogypsum.

[0004] Current conventional water washing methods are insufficient to remove eutectic phosphorus from phosphogypsum. Therefore, it is necessary to provide a method for extracting eutectic phosphorus from phosphogypsum. Summary of the Invention

[0005] In view of this, the present invention provides an extractant and method for extracting eutectic phosphorus from phosphogypsum to overcome the deficiencies in the prior art.

[0006] In a first aspect, the present invention provides an extractant for extracting eutectic phosphorus from phosphogypsum, comprising the following components by weight: 10-200 parts of extractant and 1-50 parts of extractant.

[0007] Preferably, the leaching agent for extracting eutectic phosphorus from phosphogypsum includes at least one of phosphate ester, isopropyl ether, and kerosene.

[0008] Preferably, the leaching agent for extracting the eutectic phosphorus in the phosphogypsum comprises at least one of potassium hydrogen phthalate, citric acid, boric acid, hydrochloric acid, sulfuric acid, sodium sulfate, and sodium chloride.

[0009] Preferably, the leaching agent for extracting the eutectic phosphorus in the phosphogypsum comprises a mixture of potassium hydrogen phthalate, citric acid, and sodium sulfate.

[0010] Preferably, the leaching agent for extracting the eutectic phosphorus in the phosphogypsum comprises potassium hydrogen phthalate, citric acid, and sodium sulfate in a mass ratio of (10-30):(5-15):(2-8).

[0011] Preferably, the leaching agent for extracting the eutectic phosphorus in the phosphogypsum comprises a mixture of phosphoric acid ester, isopropyl ether, and kerosene.

[0012] Preferably, the leaching agent for extracting the eutectic phosphorus in the phosphogypsum comprises components in a mass fraction of 60-70% of phosphoric acid ester, 15-20% of isopropyl ether, and 15-20% of kerosene.

[0013] In a second aspect, the present application further provides a method for extracting the eutectic phosphorus in the phosphogypsum, comprising the following steps:

[0014] After the leaching agent is mixed with the phosphogypsum, water is added, wet grinding is performed, and then solid-liquid separation is performed to obtain the phosphogypsum after washing.

[0015] Preferably, in the method for extracting the eutectic phosphorus in the phosphogypsum, after the leaching agent is mixed with the phosphogypsum, water is added, wet grinding is performed until the content of the phosphogypsum with a particle size of ≤120 μm in the total phosphogypsum is more than 60%, and then the wet grinding is stopped, and then solid-liquid separation is performed to obtain the phosphogypsum after washing.

[0016] Preferably, in the method for extracting the eutectic phosphorus in the phosphogypsum, the mass ratio of the leaching agent, the phosphogypsum, and water is 1:(5-15):(5-20).

[0017] The temperature during the wet grinding is controlled to be 20-25°C.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] 1. The leaching agent for extracting the eutectic phosphorus in the phosphogypsum of the present application comprises an extraction agent and a leaching agent, the eutectic phosphorus in the crystal lattice is released by the leaching agent and transferred to the water body, and then the dissolved eutectic phosphorus and soluble phosphorus in the water are enriched in the organic phase by the extraction agent, so that the separation of P and F is realized, the concentration difference of phosphorus between the phosphogypsum and the water body is increased, the release of phosphorus is accelerated, the washing time is shortened, the effective extraction of the eutectic phosphorus in the phosphogypsum is realized, and the recycling of the eutectic phosphorus and the soluble phosphorus is realized.

[0020] 2. The method for extracting the eutectic phosphorus in the phosphogypsum according to the present application adopts the method of combining "physics + chemistry" to promote the release of the eutectic phosphorus; the wet grinding is used to reshape the appearance of the phosphogypsum, break the surface lattice, release all the soluble phosphorus and a small part of the eutectic phosphorus into the water body; the extractant is used to enrich the phosphorus in the water into the organic phase, expand the concentration difference of the phosphorus between the phosphogypsum and the water, accelerate the release of the phosphorus, thereby shortening the washing time and reducing the water consumption; the wet grinding of the present application can achieve the effect of the traditional three times of water washing only by one time of water washing, greatly reducing the water consumption, and meanwhile, the wet grinding also improves the surface appearance of the phosphogypsum and enhances the flowability of the phosphogypsum, thereby reducing the water consumption when the phosphogypsum is used as building materials. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described in combination with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0022] It should be noted that the sequence of the following embodiments is not used as a limitation on the preferred sequence of the embodiments. In addition, in the description of the present application, the term "comprising" means "including but not limited to". Various embodiments of the present application can exist in the form of a range; it should be understood that the description in the form of a range is only for the convenience and brevity, and should not be understood as a hard limitation on the scope of the present application; therefore, it should be considered that the described range has been specifically disclosed all possible sub-ranges and single values in the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed the sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and the single numbers in the range, such as 1, 2, 3, 4, 5 and 6, which is applicable regardless of the range. In addition, whenever a numerical range is indicated in this text, it refers to any cited number (fraction or integer) within the indicated range.

[0023] The leaching agent for extracting the eutectic phosphorus in the phosphogypsum provided by the embodiments of the present application comprises the following components in parts by weight: extractant 10-200 parts, extracting agent 1-50 parts.

[0024] The leaching agent for extracting the eutectic phosphorus in the phosphogypsum of the present application comprises the extractant and the extracting agent, the eutectic phosphorus in the crystal lattice is released by the extracting agent and transferred into the water body, and then the dissolved eutectic phosphorus and soluble phosphorus in the water are enriched into the organic phase by the extractant, so as to realize the separation of P and F, increase the concentration difference of the phosphorus between the phosphogypsum and the water body, accelerate the release of the phosphorus, shorten the washing time, and realize the effective extraction of the eutectic phosphorus in the phosphogypsum, and the recycling of the eutectic phosphorus and the soluble phosphorus.

[0025] In some embodiments, the extractant includes at least one of phosphate ester, isopropyl ether, and kerosene.

[0026] In some embodiments, the extractant includes at least one selected from potassium hydrogen phthalate, citric acid, boric acid, hydrochloric acid, sulfuric acid, sodium sulfate, and sodium chloride.

[0027] In some embodiments, the extractant comprises a mixture of potassium hydrogen phthalate, citric acid, and sodium sulfate.

[0028] In some embodiments, the mass ratio of potassium hydrogen phthalate, citric acid and sodium sulfate is (10-30):(5-15):(2-8).

[0029] In some embodiments, the extractant comprises a mixture of phosphate ester, isopropyl ether, and kerosene.

[0030] In some embodiments, the extractant comprises the following components by mass fraction: 60-70% phosphate ester, 15-20% isopropyl ether, and 15-20% kerosene.

[0031] Based on the same inventive concept, the present invention also provides a method for extracting eutectic phosphorus from phosphogypsum, comprising the following steps:

[0032] After mixing the above-mentioned extractant with phosphogypsum, water is added, and the mixture is wet-milled. Solid-liquid separation is then performed to obtain water-washed phosphogypsum.

[0033] In some embodiments, the above-mentioned extractant is mixed with phosphogypsum, and then water is added. The mixture is wet-milled until the phosphogypsum particles with a diameter ≤120μm account for more than 60% of the total mass of the phosphogypsum. The mixture is then separated into solid and liquid components to obtain water-washed phosphogypsum.

[0034] In some embodiments, the mass ratio of the extractant, phosphogypsum and water is 1:(5-15):(5-20).

[0035] In some embodiments, the temperature is controlled at 20-25°C during wet milling, preferably room temperature (25°C).

[0036] The present invention provides a method for extracting eutectic phosphorus from phosphogypsum using a combination of physical and chemical methods to promote the release of eutectic phosphorus. Wet milling reshapes the morphology of phosphogypsum, breaking the surface lattice and releasing all soluble phosphorus and a small portion of eutectic phosphorus into the water. An extractant enriches phosphorus in the organic phase, increasing the phosphorus concentration difference between phosphogypsum and water, accelerating phosphorus release, thereby shortening washing time and reducing water consumption. The wet milling method of this invention achieves the effect of three traditional water washes with only one wash, significantly reducing water consumption. Simultaneously, wet milling improves the surface morphology of phosphogypsum and enhances its fluidity, further reducing water requirements when used as a building material.

[0037] The following further illustrates the leaching agent and method for extracting eutectic phosphorus in phosphogypsum according to the present application with specific examples. This part further illustrates the content of the present application in combination with specific examples, but should not be understood as a limitation of the present application. Unless specifically stated, the technical means adopted in the examples are conventional means familiar to those skilled in the art. Unless specifically stated, the reagents, methods and equipment adopted in the present application are conventional reagents, methods and equipment in the art.

[0038] Example 1

[0039] The present example provides a leaching agent for extracting eutectic phosphorus in phosphogypsum, which comprises an extraction agent (specifically comprising a mixture of 10 mL of tributyl phosphate and 10 mL of isopropyl ether) and an extracting agent (specifically comprising a mixture of 4 g of potassium hydrogen phthalate, 2 g of citric acid and 2 g of sodium sulfate).

[0040] The present example also provides a method for extracting eutectic phosphorus in phosphogypsum, which comprises the following steps:

[0041] After mixing 100 g of phosphogypsum, 100 g of water, the extraction agent (specifically comprising a mixture of 10 mL of tributyl phosphate and 10 mL of isopropyl ether) and the extracting agent (a mixture of 4 g of potassium hydrogen phthalate, 2 g of citric acid and 2 g of sodium sulfate), wet grinding is performed at room temperature (25°C) until the content of phosphogypsum with a particle size of ≤120 μm in the phosphogypsum is more than 60% of the total mass of the phosphogypsum, and then solid-liquid separation is performed to obtain the water-washed phosphogypsum.

[0042] Example 2

[0043] The present example provides a leaching agent for extracting eutectic phosphorus in phosphogypsum, which comprises an extraction agent (specifically comprising a mixture of 60 mL of tributyl phosphate, 20 mL of isopropyl ether and 20 mL of kerosene) and an extracting agent (specifically comprising a mixture of 30 g of potassium hydrogen phthalate, 15 g of citric acid and 6 g of sodium sulfate).

[0044] The present example also provides a method for extracting eutectic phosphorus in phosphogypsum, which comprises the following steps:

[0045] After mixing 1000 g of phosphogypsum, 1200 g of water, the extraction agent (specifically comprising a mixture of 60 mL of tributyl phosphate, 20 mL of isopropyl ether and 20 mL of kerosene) and the extracting agent (a mixture of 30 g of potassium hydrogen phthalate, 15 g of citric acid and 6 g of sodium sulfate), wet grinding is performed at room temperature (25°C) until the content of phosphogypsum with a particle size of ≤120 μm in the phosphogypsum is more than 60% of the total mass of the phosphogypsum, and then solid-liquid separation is performed to obtain the water-washed phosphogypsum.

[0046] Example 3

[0047] The embodiment of the present application provides a leaching agent for extracting eutectic phosphorus in phosphogypsum, which comprises an extractant (specifically comprising a mixture of 100 mL of tributyl phosphate, 60 mL of isopropyl ether and 20 mL of kerosene) and an extracting agent (specifically comprising a mixture of 45 g of potassium hydrogen phthalate, 18 g of citric acid and 9 g of sodium sulfate).

[0048] The embodiment also provides a method for extracting eutectic phosphorus in phosphogypsum, which comprises the following steps:

[0049] After the phosphogypsum 2000 g, water 3000 g, the extractant (specifically comprising a mixture of 100 mL of tributyl phosphate, 60 mL of isopropyl ether and 20 mL of kerosene) and the extracting agent (a mixture of 45 g of potassium hydrogen phthalate, 18 g of citric acid and 9 g of sodium sulfate) are mixed, wet grinding is performed at room temperature (25 DEG C) until the content of the phosphogypsum with a particle size of less than or equal to 120 mu m in the phosphogypsum is more than 60% of the total mass of the phosphogypsum, and then solid-liquid separation is performed to obtain the phosphogypsum after water washing.

[0050] Comparative Example 1

[0051] The comparative example provides a method for extracting eutectic phosphorus in phosphogypsum, which comprises the following steps:

[0052] After the phosphogypsum 100 g and water 300 g are mixed, beating is performed, and then stirring is performed for 15 min, and then filtration is performed.

[0053] 300 g of water is added to the filtered phosphogypsum to directly perform filtration, and the step is repeated twice (i.e., 300 g of water is added to the filtered phosphogypsum to directly perform filtration, and the step is repeated twice), and then the phosphogypsum after water washing is obtained.

[0054] Performance test

[0055] The content of soluble phosphorus and eutectic phosphorus in the original phosphogypsum (i.e., the phosphogypsum before water washing) and the phosphogypsum after water washing used in the test examples 1 to 3 and the comparative example 1 is tested, and the results are shown in the following table 1.

[0056] Table 1-Content of soluble phosphorus and eutectic phosphorus in the original phosphogypsum and the phosphogypsum after water washing used in the test examples 1 to 3 and the comparative example 1

[0057]

[0058] Soluble phosphorus detection

[0059] First, the phosphogypsum samples before and after treatment are prepared according to the sample preparation standard (HJ 557-2010 Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method) cited in GB 18599-2020 General Industrial Solid Waste Storage and Filling Pollution Control Standard, then the water quality analyzer is used to determine the content of phosphorus in the leaching solution according to HJ 671-2013 Water Quality Total Phosphorus Determination Flow Injection-Ammonium Molybdate Spectrophotometric Method.

[0060] Eutectic phosphorus detection

[0061] The sample from which the water-soluble phosphorus is removed by washing is dried at 40 DEG C. 5g of the sample is weighed and placed in a 100mL pH = 4 potassium hydrogen phthalate buffer solution and shaken, 80mL of 10% Ba(NO3)2 solution is added and shaken, and then diluted to 500mL in a volumetric flask, filtered, and the filtrate is removed and tested for eutectic phosphorus content according to GB / T 223.61-1988 Steel and Alloy Chemical Analysis Method Phosphorus Determination by Ammonium Molybdate Volumetric Method.

[0062] The water-soluble phosphorus in the phosphogypsum is converted to water-soluble P2O5 according to the following chemical reaction equation, expressed as C P :

[0063]

[0064] TP x 10 -3 C P ;

[0065] (unit: wt%)

[0066] As can be seen from Table 1, the eutectic phosphorus in the phosphogypsum can be effectively extracted by the method of the present application.

[0067] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for extracting eutectic phosphorus from phosphogypsum, characterized in that, Includes the following steps: After mixing the extractant with phosphogypsum, water is added, and wet milling is stopped when phosphogypsum particles with a diameter ≤120μm account for more than 60% of the total mass of phosphogypsum. Solid-liquid separation is then performed to obtain water-washed phosphogypsum. The mass ratio of the extractant, phosphogypsum, and water is 1:(5-15):(5-20); During wet grinding, the temperature should be controlled at 20–25℃. The leaching agent comprises the following components in parts by weight: 10-200 parts of extractant and 1-50 parts of extractant; The extractant comprises a mixture of potassium hydrogen phthalate, citric acid, and sodium sulfate; The mass ratio of potassium hydrogen phthalate, citric acid and sodium sulfate is (10-30):(5-15):(2-8); The extractant comprises the following components by mass fraction: 60-70% phosphate ester, 15-20% isopropyl ether, and 15-20% kerosene; the phosphate ester is tributyl phosphate.

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