WO2024087546A1 - Method for producing phosphogypsum by hemihydrate-dihydrate wet process phosphoric acid process - Google Patents

Method for producing phosphogypsum by hemihydrate-dihydrate wet process phosphoric acid process Download PDF

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WO2024087546A1
WO2024087546A1 PCT/CN2023/089825 CN2023089825W WO2024087546A1 WO 2024087546 A1 WO2024087546 A1 WO 2024087546A1 CN 2023089825 W CN2023089825 W CN 2023089825W WO 2024087546 A1 WO2024087546 A1 WO 2024087546A1
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Prior art keywords
phosphogypsum
slurry
calcium sulfate
dihydrate
phosphoric acid
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PCT/CN2023/089825
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French (fr)
Chinese (zh)
Inventor
王杰
郑光明
李防
付海军
邹学勇
邓光政
彭涛
黄鑫
黄传国
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宜都兴发化工有限公司
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Publication of WO2024087546A1 publication Critical patent/WO2024087546A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F11/00—Compounds of calcium, strontium, or barium
    • C01F11/46—Sulfates
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/18—Phosphoric acid
    • C01B25/22—Preparation by reacting phosphate-containing material with an acid, e.g. wet process
    • C01B25/222—Preparation by reacting phosphate-containing material with an acid, e.g. wet process with sulfuric acid, a mixture of acids mainly consisting of sulfuric acid or a mixture of compounds forming it in situ, e.g. a mixture of sulfur dioxide, water and oxygen
    • C01B25/228—Preparation by reacting phosphate-containing material with an acid, e.g. wet process with sulfuric acid, a mixture of acids mainly consisting of sulfuric acid or a mixture of compounds forming it in situ, e.g. a mixture of sulfur dioxide, water and oxygen one form of calcium sulfate being formed and then converted to another form
    • C01B25/229—Hemihydrate-dihydrate process
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B11/00—Calcium sulfate cements
    • C04B11/26—Calcium sulfate cements strating from chemical gypsum; starting from phosphogypsum or from waste, e.g. purification products of smoke

Definitions

  • the invention relates to the technical field of phosphorus chemical industry, and in particular to a method for producing high-quality phosphogypsum through a semi-aqueous-dihydrate wet phosphoric acid process.
  • the global annual production of phosphogypsum is 200 million tons, the cumulative stockpile exceeds 6 billion tons, and the comprehensive utilization rate is only about 25%.
  • the comprehensive utilization rate of phosphogypsum is closely related to the quality of phosphogypsum.
  • the use of a new wet phosphoric acid process to improve the quality of phosphogypsum is a core measure for optimizing the phosphogypsum process and an important part of improving the comprehensive utilization rate of phosphogypsum.
  • the purpose of the present invention is to provide a method for producing high-quality phosphogypsum by a semi-aqueous-dihydrate wet phosphoric acid process, which has a simple process, protects the environment, and promotes a green circular economy.
  • the present invention provides a method for producing high-quality phosphogypsum by a semi-aqueous-dihydrate wet phosphoric acid process, comprising the following technical solutions:
  • a method for producing phosphogypsum by a semi-aqueous-dihydrate wet phosphoric acid process comprises the following steps:
  • the water content of the phosphate rock powder after dehydration is less than 12%; the phosphate rock powder is premixed with phosphoric acid having a mass concentration of 20-35% to obtain a slurry containing monocalcium phosphate;
  • the mass fraction of concentrated sulfuric acid in step (2) is 96-98%. After adding concentrated sulfuric acid, stirring is performed at a temperature of 90-100° C. to obtain slurry 1, in which the solid content of slurry 1 is 25-30%, and the mass fraction of liquid phase sulfate is 0.5-1.2%.
  • the mass fraction of concentrated sulfuric acid in step (3) is 96-98%. After adding concentrated sulfuric acid, the mixture is stirred at a temperature of 90-100°C to obtain slurry 2, wherein the solid content of slurry 2 is 25-30%, the mass fraction of liquid sulfate ion is 2.0-4.0%, and the liquid phase P2O5 concentration is 36-43wt%.
  • the solid content includes 75-81% calcium sulfate hemihydrate crystal content and 12-18% calcium sulfate dihydrate content.
  • the sulfate mass fraction of the second liquid phase of the slurry obtained in the step (3) is 2.0-4.0%. If the sulfate content of the liquid phase is too low or too high, the gypsum crystallization in the second slurry will change significantly, resulting in difficulty in filtering in the subsequent step (4), affecting the high water-soluble phosphorus and total phosphorus of the crude phosphogypsum obtained in the step (4).
  • the intermediate acid in step (4) is phosphoric acid, and the mass fraction of phosphoric acid is 36-43%; the semi-hydrated acid contains 20-35% of phosphoric acid and 2-4% of sulfuric acid; the phosphogypsum includes 75-81% of hemihydrate calcium sulfate, 12-18% of dihydrate calcium sulfate, 3-6% of water-soluble phosphorus, 4-7% of total phosphorus, and less than 20% of attached water.
  • the semi-water acid is recycled to step (1) to premix the phosphate rock powder to decompose it into a slurry containing monocalcium phosphate.
  • stirring is performed and the mass fraction of liquid sulfate in the slurry is controlled to be less than 0.1%.
  • the premixing process mainly improves the decomposition rate of the phosphate rock. If the liquid sulfate exceeds 2.0%, or concentrated sulfuric acid is directly added to dissolve the phosphate rock, a wrapping phenomenon may occur, which ultimately affects the total phosphorus content of the crude phosphogypsum obtained in step (4).
  • step (5) concentrated sulfuric acid is added, and stirred at 55-75°C for 2-4 hours to obtain slurry three, wherein the solid content of slurry three is 30-35%, the mass fraction of liquid sulfate is 5.0-9.0%, and the P2O5 concentration is 8-15wt%. If the conversion temperature is higher, the P2O5 concentration is higher, and the corresponding mass fraction of liquid sulfate must be controlled at a lower limit.
  • the conversion temperature, the mass fraction of liquid sulfate and the P2O5 concentration are not well matched, it will affect the conversion of calcium sulfate hemihydrate into calcium sulfate dihydrate, and further affect the high water-soluble phosphorus of the phosphogypsum obtained after filtration in the subsequent step (6).
  • the phosphogypsum obtained after filtration in step (6) comprises 10-20% by mass of calcium sulfate hemihydrate, 71-81% by mass of calcium sulfate dihydrate, 0.6-1.0% of water-soluble phosphorus, 0.8-1.3% of total phosphorus, and less than 20% of attached water;
  • the mass fraction of calcium sulfate hemihydrate in the phosphogypsum obtained after re-slurrying and dehydration in step (6) is 10-20%, the mass fraction of calcium sulfate dihydrate is 71-81%, the water-soluble phosphorus is less than 0.2%, the total phosphorus is about 0.2-0.5%, and the attached water is less than 12%.
  • the phosphogypsum and quicklime are mixed uniformly, the initial pH value of the phosphogypsum is controlled to be 6-12, and after aging for more than 3 days, a fine phosphogypsum with a calcium sulfate dihydrate content of >90% is obtained, preferably a fine phosphogypsum with a calcium sulfate dihydrate content of >92% is obtained after aging for more than 7 days.
  • the mass fraction of calcium sulfate dihydrate in the fine phosphogypsum is >90%, the water-soluble phosphorus is ⁇ 0.1%, the total phosphorus is 0.2-0.5%, the attached water is ⁇ 12%, and the pH value is 4-11.
  • Another technical solution of the present invention is to produce the hemihydrate-dihydrate phosphoric acid process by the bicrystalline phosphogypsum containing calcium sulfate hemihydrate and calcium sulfate dihydrate, wherein the content of calcium sulfate hemihydrate is 10-20%, the content of calcium sulfate dihydrate is 71-81%, the water-soluble phosphorus is about 0.6-1.0%, the total phosphorus is about 0.8-1.3%, and the attached water is less than 20%;
  • the hemihydrate-dihydrate wet phosphoric acid process contains 10-20% hemihydrate calcium sulfate, 71-81% dihydrate calcium sulfate, less than 0.2% water-soluble phosphorus, about 0.2-0.5% total phosphorus, and less than 12% attached water.
  • the present invention provides a method for producing high-quality phosphogypsum by semi-aqueous-dihydrate wet phosphoric acid process. Reduced to 0.2-0.5%, water-soluble phosphorus ⁇ 0.1%, attached water ⁇ 12%, calcium sulfate dihydrate content >90%, and the pH value of phosphogypsum can be adjusted according to different application scenarios;
  • the average phosphorus recovery rate can reach more than 98%
  • the P2O5 concentration of the finished acid is 36-43wt%, and less steam is required for subsequent production of DAP or PPA concentration, thus saving energy and reducing consumption.
  • the embodiment of the present invention provides a method for producing high-quality phosphogypsum by a semi-aqueous-dihydrate wet phosphoric acid process, comprising the following steps:
  • the phosphate rock powder is conveyed to a premixing tank by a belt, and 20% by mass of phosphoric acid is added for premixing to decompose the phosphate rock into monocalcium phosphate, and the premix slurry is generated by stirring, and the mass fraction of sulfate in the liquid phase of the premix slurry is controlled to be less than 0.1%;
  • the premixed slurry enters the dissolution tank, and concentrated sulfuric acid (mass fraction 96-98%) is added at the same time, and the phosphate rock is further decomposed by stirring at 90-100°C to generate slurry 1, and the solid content of slurry 1 is controlled to be 25-30%, and the mass fraction of liquid sulfate in slurry 1 is 0.5-0.7%;
  • the slurry 1 enters the crystallization tank, and concentrated sulfuric acid (mass fraction 96-98%) is added at the same time, and stirred at 90-100°C to promote the phosphogypsum to form mixed crystals mainly composed of hemihydrate calcium sulfate crystals, and stirred to form slurry 2, and the solid content of slurry 2 is controlled to be 25-30%, the hemihydrate calcium sulfate content in the solid phase phosphogypsum of slurry 2 is controlled to be 78-80%, the dihydrate calcium sulfate content is controlled to be 12-15%, the mass fraction of liquid phase sulfate in slurry 2 is controlled to be 3.5-4.0%, and the P2O5 concentration is controlled to be 38-42wt%;
  • the slurry 2 is filtered to recover 38-42% of the intermediate acid (product phosphoric acid), semi-hydrated return acid (the semi-hydrated return acid contains 30-31% of phosphoric acid and 2.0-2.8% of sulfuric acid by mass) and phosphogypsum 1, wherein the content of semi-hydrated calcium sulfate in the phosphogypsum 1 is 78-80%, the content of dihydrated calcium sulfate is 12-15%, the total phosphorus is about 5-7% (including about 3-4% of water-soluble phosphorus), and the attached water is 18-19%; the semi-hydrated return acid is recycled to the phosphate rock powder for premixing and decomposition to obtain monocalcium phosphate, and the mass fraction of sulfate in the liquid phase of the premixed slurry is controlled to be less than 0.1%;
  • Phosphogypsum1 enters the conversion tank, and an appropriate amount of concentrated sulfuric acid is added at the same time, and stirred at a temperature of 55-75°C to generate slurry3, the solid content of slurry3 is controlled to be 30-35%, the mass fraction of sulfate in the filtrate of slurry3 is controlled to be 6.0-7.0%, and the P2O5 concentration is 8-14wt%;
  • the phosphogypsum 2 is conveyed to the re-slurry tank by a belt, and water is added to re-slurry to form slurry 4, and the solid content of slurry 4 is controlled to be 30-40%;
  • phosphogypsum 3 wherein the content of hemihydrate calcium sulfate in the phosphogypsum 3 is 10-15%, the content of dihydrate calcium sulfate is 78-83%, the water-soluble phosphorus is 0.1-0.2%, the total phosphorus is about 0.3-0.4%, and the attached water is 10-12%;
  • the phosphogypsum 3 and quicklime are uniformly mixed, the initial pH value of the phosphogypsum is controlled at 6-8, and aged for more than 3 days to obtain phosphogypsum 4, in which the calcium sulfate hemihydrate is completely converted into calcium sulfate dihydrate, the content of calcium sulfate dihydrate is 91-93%, the water-soluble phosphorus is less than 0.1%, the total phosphorus is about 0.2-0.5%, the attached water is less than 9-11%, and the pH value is 4-5.
  • the embodiment of the present invention provides a method for producing high-quality phosphogypsum by a semi-aqueous-dihydrate wet phosphoric acid process, comprising the following steps:
  • the phosphate rock powder is conveyed to a premixing tank by a belt, and 20% by mass of phosphoric acid is added for premixing to decompose the phosphate rock into monocalcium phosphate, and the premix slurry is generated by stirring, and the mass fraction of sulfate in the liquid phase of the premix slurry is controlled to be less than 0.1%;
  • the premixed slurry enters the dissolution tank, and concentrated sulfuric acid (mass fraction 96-98%) is added at the same time, and the phosphate rock is further decomposed by stirring at 90-100°C to generate slurry 1, and the solid content of slurry 1 is controlled to be 28-30%, and the mass fraction of liquid sulfate in slurry 1 is 0.8-1.0%;
  • the slurry 1 enters the crystallization tank, and concentrated sulfuric acid (mass fraction 96-98%) is added at the same time, and stirred at 90-100°C to promote the phosphogypsum to form mixed crystals mainly composed of hemihydrate calcium sulfate crystals, and stirred to form slurry 2, and the solid content of slurry 2 is controlled to be 28-30%, the hemihydrate calcium sulfate content in the solid phase phosphogypsum of slurry 2 is controlled to be 78-81%, the dihydrate calcium sulfate content is controlled to be 13-16%, the mass fraction of liquid phase sulfate in slurry 2 is controlled to be 2.5-3.0%, and the P2O5 concentration is 38-42.5wt%;
  • the slurry 2 is filtered to recover 37.8-42% of intermediate acid (product phosphoric acid), semi-hydrated return acid (the semi-hydrated return acid contains 20-29% by mass of phosphoric acid and 2.0-2.6% by mass of sulfuric acid) and phosphogypsum 1, wherein the content of semi-hydrated calcium sulfate in the phosphogypsum 1 is 78-81%, the content of dihydrated calcium sulfate is 13-16%, the total phosphorus is about 4-7% (including about 3-5% of water-soluble phosphorus), and the attached water is 18.5-19.5%; the semi-hydrated return acid is recycled to the phosphate rock powder for decomposition to obtain monocalcium phosphate, and the mass fraction of sulfate in the liquid phase of the premixed slurry is controlled to be less than 0.1%;
  • the phosphogypsum 1 enters the conversion tank, and an appropriate amount of concentrated sulfuric acid is added at the same time, and the slurry 3 is stirred at a temperature of 55-75°C to form the slurry 3, and the solid content of the slurry 3 is controlled to be 31-34%, the content of hemihydrate calcium sulfate in the solid phase phosphogypsum of the slurry 3 is controlled to be 13-16%, the content of dihydrate calcium sulfate is controlled to be 77-81%, the mass fraction of sulfate ion in the liquid phase of the slurry 3 is controlled to be 7.0-8.0%, and the concentration of P2O5 is controlled to be 11-15wt%;
  • the phosphogypsum 2 is conveyed to the re-slurry tank by a belt, and water is added to re-slurry to form slurry 4, and the solid content of slurry 4 is controlled to be 32-40%;
  • phosphogypsum 3 Dehydrating the slurry 4 to obtain phosphogypsum 3, wherein the content of hemihydrate calcium sulfate in the phosphogypsum 3 is 13-15%, the content of dihydrate calcium sulfate is 77-81%, the water-soluble phosphorus is less than 0.2%, the total phosphorus is about 0.2-0.5%, and the attached water is 10-11.5%;
  • the phosphogypsum 3 and quicklime are uniformly mixed, the initial pH value of the phosphogypsum is controlled at 6-8, and aged for more than 3 days to obtain phosphogypsum 4, in which the calcium sulfate hemihydrate is completely converted into calcium sulfate dihydrate, the calcium sulfate dihydrate content is 92.2-93.5%, the water-soluble phosphorus is less than 0.1%, the total phosphorus is about 0.2-0.5%, the attached water is 10-11%, and the pH value is 4-5.
  • the embodiment of the present invention provides a method for producing high-quality phosphogypsum by a semi-aqueous-dihydrate wet phosphoric acid process, comprising the following steps:
  • the phosphate rock powder is conveyed to a premixing tank by a belt, and 20% by mass of phosphoric acid is added for premixing to decompose the phosphate rock into monocalcium phosphate, and the premix slurry is generated by stirring, and the mass fraction of sulfate in the liquid phase of the premix slurry is controlled to be less than 0.1%;
  • the premixed slurry enters the dissolution tank, and concentrated sulfuric acid (mass fraction 96-98%) is added at the same time, and the phosphate rock is further decomposed by stirring at 90-100°C to generate slurry 1, and the solid content of slurry 1 is controlled to be 25-30%, and the mass fraction of liquid sulfate in slurry 1 is 1.0-1.2%;
  • the slurry 1 enters the crystallization tank, and concentrated sulfuric acid (mass fraction 96-98%) is added at the same time, and stirred at 90-100°C to promote the phosphogypsum to form mixed crystals mainly composed of hemihydrate calcium sulfate crystals, and stirred to form slurry 2, and the solid content of slurry 2 is controlled to be 25-30%, the hemihydrate calcium sulfate content in the solid phase phosphogypsum of slurry 2 is controlled to be 75-81%, the dihydrate calcium sulfate content is controlled to be 12-18%, the mass fraction of liquid phase sulfate in slurry 2 is controlled to be 2.5-3.5%, and the P2O5 concentration is 38-41wt%;
  • the slurry 2 is filtered to recover 37.5-41% of intermediate acid (product phosphoric acid), semi-hydrated return acid (the semi-hydrated return acid contains 20-28% by mass of phosphoric acid and 2.1-2.5% by mass of sulfuric acid) and phosphogypsum 1, wherein the content of semi-hydrated calcium sulfate in the phosphogypsum 1 is 75-81%, the content of dihydrated calcium sulfate is 12-18%, the total phosphorus is about 5-7% (including about 5-6% of water-soluble phosphorus), and the attached water is 19-20%; the semi-hydrated return acid is recycled to the phosphate rock powder for decomposition to obtain monocalcium phosphate, and the mass fraction of sulfate in the liquid phase of the premixed slurry is controlled to be less than 0.1%;
  • the phosphogypsum 1 enters the conversion tank, and an appropriate amount of concentrated sulfuric acid is added at the same time, and the slurry 3 is stirred at a temperature of 55-75°C, and the solid content of the slurry 3 is controlled to be 32-35%, the content of hemihydrate calcium sulfate in the solid phase phosphogypsum of the slurry 3 is controlled to be 11-15%, the content of dihydrate calcium sulfate is controlled to be 76-80%, the mass fraction of sulfate ion in the liquid phase of the slurry 3 is controlled to be 5.0-7.0%, and the concentration of P2O5 is controlled to be 8-12wt%;
  • the phosphogypsum 2 is conveyed to the re-slurry tank by a belt, and water is added to re-slurry to form slurry 4, and the solid content of slurry 4 is controlled to be 32-40%;
  • the slurry 4 is dehydrated to obtain phosphogypsum 3, wherein the content of hemihydrate calcium sulfate in the phosphogypsum 3 is 10-15%, and the content of dihydrate calcium sulfate is 10-15%.
  • the calcium content is 76-81%, water-soluble phosphorus is less than 0.2%, total phosphorus is about 0.2-0.5%, and attached water is 11-12%;
  • the phosphogypsum 3 and quicklime are uniformly mixed, the initial pH value of the phosphogypsum is controlled at 6-8, and aged for more than 3 days to obtain phosphogypsum 4, in which the calcium sulfate hemihydrate is completely converted into calcium sulfate dihydrate, the calcium sulfate dihydrate content is 90.6-91.5%, the water-soluble phosphorus is less than 0.1%, the total phosphorus is about 0.2-0.5%, the attached water is 9-11%, and the pH value is 4-5.
  • the dehydrated phosphate rock powder is directly added with concentrated sulfuric acid at a mass fraction of 96-98% without adding 20% dilute phosphoric acid for premixing, and the concentrated sulfuric acid is added and stirred at a temperature of 90-100°C to obtain slurry 1.
  • the final phosphogypsum 3 has a hemihydrate calcium sulfate content of 10-20%, a dihydrate calcium sulfate content of 70-80%, water-soluble phosphorus ⁇ 0.2%, total phosphorus of about 0.5-0.8%, and attached water ⁇ 12%;
  • the phosphogypsum 3 and quicklime are uniformly mixed, the initial pH value of the phosphogypsum is controlled at 6-8, and aged for more than 3 days to obtain phosphogypsum 4, in which the calcium sulfate hemihydrate is completely converted into calcium sulfate dihydrate, the content of calcium sulfate dihydrate is 90.8%, the water-soluble phosphorus is less than 0.1%, the total phosphorus is about 0.5-0.8%, the attached water is 9-11%, and the pH value is 4-5.
  • Example 1 of the present application Compared with Example 1 of the present application, the premixed slurry enters the dissolution tank, and concentrated sulfuric acid (mass fraction 96-98%) is added to further decompose the phosphate rock, and the slurry is kept for 4 hours to generate slurry 1, and the mass fraction of sulfate ions in the liquid phase of slurry 1 is controlled at 1.5%, the temperature of slurry 1 is controlled at 90-100° C., and the solid content of slurry 1 is controlled at 37%;
  • the final phosphogypsum 3 has a hemihydrate calcium sulfate content of 15-27%, a dihydrate calcium sulfate content of 60-77%, water-soluble phosphorus ⁇ 0.2%, total phosphorus of about 0.4-1.1% (with a large fluctuation range and instability), and attached water ⁇ 12%;
  • the phosphogypsum 3 and quicklime are mixed evenly, the initial pH value of the phosphogypsum is controlled at 6-8, and aged for more than seven days to obtain phosphogypsum 4, in which the calcium sulfate hemihydrate is completely converted into calcium sulfate dihydrate, the content of calcium sulfate dihydrate is 89.5%, the water-soluble phosphorus is less than 0.1%, the total phosphorus is about 0.4-1.1%, the attached water is 8-10%, and the pH value is 4-5.
  • slurry 1 enters the crystallization tank, and concentrated sulfuric acid (mass fraction 96-98%) is added to promote the phosphogypsum to form mixed crystals mainly composed of hemihydrate calcium sulfate crystals, and stays for 3 hours to generate slurry 2, and the mass fraction of sulfate ions in the liquid phase of slurry 2 is controlled to be 1.2%, the concentration of P2O5 is 41wt%, the temperature of slurry 2 is controlled to be 90-100°C, and the solid content of slurry 3 is controlled to be 36%;
  • the final phosphogypsum 3 has a content of calcium sulfate hemihydrate of 5-18%, a content of calcium sulfate dihydrate of 68-82%, water-soluble phosphorus of about 0.8-1.5%, total phosphorus of about 1.1-1.9%, and attached water of ⁇ 12%;
  • the phosphogypsum 3 and quicklime are mixed evenly, the initial pH value of the phosphogypsum is controlled at 6-8, and the phosphogypsum is aged for more than seven days to obtain phosphogypsum 4, and the hemihydrate calcium sulfate in the phosphogypsum 4 is completely converted into dihydrate calcium sulfate, the dihydrate calcium sulfate content is 91.5%, and the water-soluble phosphorus is less than 0.2%, total phosphorus is about 1.0-1.9%, attached water is 8.5-10%, and the pH value is 3.2-5.6.
  • phosphogypsum 1 enters the conversion tank, and an appropriate amount of concentrated sulfuric acid is added at the same time, and the mixture stays for 1.5 hours to generate slurry 3, and the mass fraction of sulfate ions in the liquid phase of slurry 3 is controlled to be 11.5%, the concentration of P2O5 is 15wt%, the temperature of slurry 3 is controlled to be 80°C, and the solid content of slurry 3 is controlled to be 27%;
  • the final phosphogypsum 3 has a content of calcium sulfate hemihydrate of 17-26%, a content of calcium sulfate dihydrate of 65-75%, a water-soluble phosphorus of about 0.4-0.7%, a total phosphorus of about 0.7-1.0%, and an adhering water content of ⁇ 12%;
  • the phosphogypsum 3 and quicklime are uniformly mixed, the initial pH value of the phosphogypsum is controlled at 6-8, and aged for more than seven days to obtain phosphogypsum 4, in which the calcium sulfate hemihydrate is completely converted into calcium sulfate dihydrate, the content of calcium sulfate dihydrate is 92.6%, the water-soluble phosphorus is less than 0.1%, the total phosphorus is about 0.7-1.0%, the attached water is 8-10%, and the pH value is 3.8-4.7.

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Abstract

Provided are a method for producing phosphogypsum by a hemihydrate-dihydrate wet process phosphoric acid process and phosphogypsum produced by the method. The method comprises: (1) dehydrating phosphate rock slurry to obtain phosphate rock powder; (2) adding concentrated sulfuric acid into the phosphate rock powder for dissolution to obtain a slurry I; (3) adding concentrated sulfuric acid into the slurry I for crystallization to obtain a slurry II; (4) filtering the slurry II to obtain an intermediate acid, a hemihydrate returned acid and crude phosphogypsum; (5) adding concentrated sulfuric acid into the crude phosphogypsum for conversion to obtain a slurry III; (6) filtering the slurry III, adding water for re-slurrying, and dehydrating to obtain phosphogypsum; and (7) uniformly mixing the phosphogypsum with quicklime, and aging to obtain fine phosphogypsum. The method is simple, easy to control, green, and environmentally friendly, leaves no dilute sulfuric acid residue, and achieves high phosphorus yield and good phosphogypsum quality.

Description

一种半水-二水湿法磷酸工艺生产磷石膏的方法A method for producing phosphogypsum by semi-aqueous-dihydrate wet phosphoric acid process 技术领域Technical Field
本发明涉及磷化工技术领域，具体涉及一种半水-二水湿法磷酸工艺生产高品质磷石膏的方法。The invention relates to the technical field of phosphorus chemical industry, and in particular to a method for producing high-quality phosphogypsum through a semi-aqueous-dihydrate wet phosphoric acid process.
技术背景technical background
全球磷石膏年产生量2亿吨，累计堆存量超60亿吨，综合利用率仅25％左右，磷石膏综合利用率与磷石膏品质息息相关，为实现磷石膏产销动态平衡，采用湿法磷酸新工艺提高磷石膏品质是磷石膏过程优化的核心举措，是提高磷石膏综合利用率的重要一环。The global annual production of phosphogypsum is 200 million tons, the cumulative stockpile exceeds 6 billion tons, and the comprehensive utilization rate is only about 25%. The comprehensive utilization rate of phosphogypsum is closely related to the quality of phosphogypsum. In order to achieve a dynamic balance between the production and sales of phosphogypsum, the use of a new wet phosphoric acid process to improve the quality of phosphogypsum is a core measure for optimizing the phosphogypsum process and an important part of improving the comprehensive utilization rate of phosphogypsum.
发明内容Summary of the invention
本发明的目的是提供一种工艺简单、保护环境、助推绿色循环经济的半水-二水湿法磷酸工艺生产高品质磷石膏的方法。The purpose of the present invention is to provide a method for producing high-quality phosphogypsum by a semi-aqueous-dihydrate wet phosphoric acid process, which has a simple process, protects the environment, and promotes a green circular economy.
为解决上述技术问题，本发明提供一种半水-二水湿法磷酸工艺生产高品质磷石膏的方法，包括以下技术方案：In order to solve the above technical problems, the present invention provides a method for producing high-quality phosphogypsum by a semi-aqueous-dihydrate wet phosphoric acid process, comprising the following technical solutions:
一种半水-二水湿法磷酸工艺生产磷石膏的方法，包括以下步骤：A method for producing phosphogypsum by a semi-aqueous-dihydrate wet phosphoric acid process comprises the following steps:
(1)对磷矿浆进行脱水，得到磷矿粉；(1) dehydrating the phosphate slurry to obtain phosphate rock powder;
(2)将磷矿粉加入浓硫酸进行溶解，得到料浆一；(2) adding concentrated sulfuric acid to dissolve phosphate rock powder to obtain slurry 1;
(3)将料浆一加入浓硫酸进行结晶，得到料浆二；(3) adding concentrated sulfuric acid to slurry 1 for crystallization to obtain slurry 2;
(4)将料浆二过滤得到中间酸、半水返酸和磷石膏粗品；(4) filtering the slurry II to obtain intermediate acid, semi-hydrated acid and crude phosphogypsum;
(5)将磷石膏粗品加入浓硫酸进行转化，得到料浆三；(5) adding concentrated sulfuric acid to the crude phosphogypsum for conversion to obtain slurry three;
(6)将料浆三经过滤、加水再浆、脱水后得到磷石膏；(6) filtering the slurry, adding water to re-slurry, and dehydrating to obtain phosphogypsum;
(7)将磷石膏加生石灰混合均匀，陈化后得到磷石膏精品。(7) Mix phosphogypsum and quicklime evenly, and obtain fine phosphogypsum after aging.
所述的步骤(1)中磷矿粉经脱水后含水量低于12％；磷矿粉加入质量浓度为20-35％的磷酸进行预混，得到含磷酸一钙的料浆；In the step (1), the water content of the phosphate rock powder after dehydration is less than 12%; the phosphate rock powder is premixed with phosphoric acid having a mass concentration of 20-35% to obtain a slurry containing monocalcium phosphate;
所述的步骤(2)中浓硫酸的质量分数为96-98％，加入浓硫酸后在温度为90-100℃下搅拌得到料浆一，料浆一中固含量为25-30％，液相硫酸根质量分数在0.5-1.2％。The mass fraction of concentrated sulfuric acid in step (2) is 96-98%. After adding concentrated sulfuric acid, stirring is performed at a temperature of 90-100° C. to obtain slurry 1, in which the solid content of slurry 1 is 25-30%, and the mass fraction of liquid phase sulfate is 0.5-1.2%.
所述的步骤(3)中浓硫酸的质量分数为96-98％，加入浓硫酸后在温度为90-100℃下搅拌得到料浆二，料浆二中固含量为25-30％，液相硫酸根质量分数在2.0-4.0％，液相P2O5浓度为36-43wt％；所述的固含量中包括半水硫酸钙晶体含量在75-81％，二水硫酸钙含量在12-18％。 The mass fraction of concentrated sulfuric acid in step (3) is 96-98%. After adding concentrated sulfuric acid, the mixture is stirred at a temperature of 90-100°C to obtain slurry 2, wherein the solid content of slurry 2 is 25-30%, the mass fraction of liquid sulfate ion is 2.0-4.0%, and the liquid phase P2O5 concentration is 36-43wt%. The solid content includes 75-81% calcium sulfate hemihydrate crystal content and 12-18% calcium sulfate dihydrate content.
所述的步骤(3)中得到的料浆二液相硫酸根质量分数在2.0-4.0％，若液相硫酸根含量过低或过高，料浆二中石膏结晶会发生明显变化，导致后续步骤(4)中过滤困难，影响步骤(4)得到的磷石膏粗品水溶磷和总磷均较高。The sulfate mass fraction of the second liquid phase of the slurry obtained in the step (3) is 2.0-4.0%. If the sulfate content of the liquid phase is too low or too high, the gypsum crystallization in the second slurry will change significantly, resulting in difficulty in filtering in the subsequent step (4), affecting the high water-soluble phosphorus and total phosphorus of the crude phosphogypsum obtained in the step (4).
所述步骤(4)的中间酸为磷酸，磷酸质量分数为36-43％；所述的半水返酸中含质量分数为20-35％的磷酸及质量分数为2-4％的硫酸；所述的磷石膏中包括质量分数在75-81％半水硫酸钙，质量分数在12-18％二水硫酸钙，水溶磷为3-6％，总磷为4-7％，附着水＜20％。The intermediate acid in step (4) is phosphoric acid, and the mass fraction of phosphoric acid is 36-43%; the semi-hydrated acid contains 20-35% of phosphoric acid and 2-4% of sulfuric acid; the phosphogypsum includes 75-81% of hemihydrate calcium sulfate, 12-18% of dihydrate calcium sulfate, 3-6% of water-soluble phosphorus, 4-7% of total phosphorus, and less than 20% of attached water.
所述的半水返酸回用至步骤(1)中，对磷矿粉进行预混使其分解成含磷酸一钙的料浆，预混过程中搅拌，同时控制料浆中液相硫酸根质量分数＜0.1％，预混过程主要提高磷矿分解率。若液相硫酸根超过2.0％，或者直接加浓硫酸溶解磷矿，可能会出现包裹现象，最终影响步骤(4)中得到的磷石膏粗品总磷较高。The semi-water acid is recycled to step (1) to premix the phosphate rock powder to decompose it into a slurry containing monocalcium phosphate. During the premixing process, stirring is performed and the mass fraction of liquid sulfate in the slurry is controlled to be less than 0.1%. The premixing process mainly improves the decomposition rate of the phosphate rock. If the liquid sulfate exceeds 2.0%, or concentrated sulfuric acid is directly added to dissolve the phosphate rock, a wrapping phenomenon may occur, which ultimately affects the total phosphorus content of the crude phosphogypsum obtained in step (4).
所述步骤(5)中加入浓硫酸，在55-75℃下搅拌2-4小时得到料浆三，料浆三中含固量在30-35％，液相硫酸根质量分数在5.0-9.0％，P2O5浓度为8-15wt％。若转化温度越高，P2O5浓度越高，液相硫酸根对应质量分数须偏下限控制，若转化温度、液相硫酸根质量分数和P2O5浓度匹配度不高，会影响半水硫酸钙转化为二水硫酸钙，进一步影响后续步骤(6)中过滤后得到的磷石膏水溶磷较高。In the step (5), concentrated sulfuric acid is added, and stirred at 55-75°C for 2-4 hours to obtain slurry three, wherein the solid content of slurry three is 30-35%, the mass fraction of liquid sulfate is 5.0-9.0%, and the P2O5 concentration is 8-15wt%. If the conversion temperature is higher, the P2O5 concentration is higher, and the corresponding mass fraction of liquid sulfate must be controlled at a lower limit. If the conversion temperature, the mass fraction of liquid sulfate and the P2O5 concentration are not well matched, it will affect the conversion of calcium sulfate hemihydrate into calcium sulfate dihydrate, and further affect the high water-soluble phosphorus of the phosphogypsum obtained after filtration in the subsequent step (6).
所述步骤(6)中过滤后得到的磷石膏中包括质量分数为10-20％的半水硫酸钙，质量分数为71-81％二水硫酸钙，水溶磷为0.6-1.0％，总磷为0.8-1.3％，附着水＜20％；The phosphogypsum obtained after filtration in step (6) comprises 10-20% by mass of calcium sulfate hemihydrate, 71-81% by mass of calcium sulfate dihydrate, 0.6-1.0% of water-soluble phosphorus, 0.8-1.3% of total phosphorus, and less than 20% of attached water;
所述步骤(6)中再浆脱水后得到的磷石膏中半水硫酸钙质量分数为10-20％，二水硫酸钙质量分数为71-81％，水溶磷＜0.2％，总磷约为0.2-0.5％，附着水＜12％。The mass fraction of calcium sulfate hemihydrate in the phosphogypsum obtained after re-slurrying and dehydration in step (6) is 10-20%, the mass fraction of calcium sulfate dihydrate is 71-81%, the water-soluble phosphorus is less than 0.2%, the total phosphorus is about 0.2-0.5%, and the attached water is less than 12%.
所述的步骤(7)中磷石膏加生石灰混合均匀，控制磷石膏初始PH值在6-12，陈化3天以上后得到二水硫酸钙含量＞90％的磷石膏精品，优选为陈化7天以上得到二水硫酸钙含量＞92％的磷石膏精品，磷石膏精品中二水硫酸钙质量分数＞90％，水溶磷＜0.1％，总磷为0.2-0.5％，附着水＜12％，PH值4-11。In the step (7), the phosphogypsum and quicklime are mixed uniformly, the initial pH value of the phosphogypsum is controlled to be 6-12, and after aging for more than 3 days, a fine phosphogypsum with a calcium sulfate dihydrate content of >90% is obtained, preferably a fine phosphogypsum with a calcium sulfate dihydrate content of >92% is obtained after aging for more than 7 days. The mass fraction of calcium sulfate dihydrate in the fine phosphogypsum is >90%, the water-soluble phosphorus is <0.1%, the total phosphorus is 0.2-0.5%, the attached water is <12%, and the pH value is 4-11.
本发明的又一技术方案是将所述的半水-二水湿法磷酸工艺生产得到的含半水硫酸钙及二水硫酸钙双晶态磷石膏，其中半水硫酸钙含量在10-20％，二水硫酸钙含量在71-81％，水溶磷约为0.6-1.0％，总磷约为0.8-1.3％，附着水＜20％；Another technical solution of the present invention is to produce the hemihydrate-dihydrate phosphoric acid process by the bicrystalline phosphogypsum containing calcium sulfate hemihydrate and calcium sulfate dihydrate, wherein the content of calcium sulfate hemihydrate is 10-20%, the content of calcium sulfate dihydrate is 71-81%, the water-soluble phosphorus is about 0.6-1.0%, the total phosphorus is about 0.8-1.3%, and the attached water is less than 20%;
或者半水-二水湿法磷酸工艺生产的含半水硫酸钙含量在10-20％，二水硫酸钙含量在71-81％，水溶磷＜0.2％，总磷约为0.2-0.5％，附着水＜12％。Or the hemihydrate-dihydrate wet phosphoric acid process contains 10-20% hemihydrate calcium sulfate, 71-81% dihydrate calcium sulfate, less than 0.2% water-soluble phosphorus, about 0.2-0.5% total phosphorus, and less than 12% attached water.
本发明提供了一种半水-二水湿法磷酸工艺生产高品质磷石膏的方法，磷石膏总磷可 降低至0.2-0.5％，水溶磷＜0.1％，附着水＜12％，二水硫酸钙含量＞90％，同时可根据不同应用场景调节磷石膏pH值；The present invention provides a method for producing high-quality phosphogypsum by semi-aqueous-dihydrate wet phosphoric acid process. Reduced to 0.2-0.5%, water-soluble phosphorus <0.1%, attached water <12%, calcium sulfate dihydrate content >90%, and the pH value of phosphogypsum can be adjusted according to different application scenarios;
磷回收率高，平均磷收率可达98％以上；High phosphorus recovery rate, the average phosphorus recovery rate can reach more than 98%;
成品酸P2O5浓度为36-43wt％，后续生产DAP或PPA浓缩所需蒸汽少，节能降耗。The P2O5 concentration of the finished acid is 36-43wt%, and less steam is required for subsequent production of DAP or PPA concentration, thus saving energy and reducing consumption.
具体实施方式Detailed ways
以下结合实施例对本发明作进一步说明，但本发明要求保护的范围并不局限于实施例表述的范围。The present invention is further described below in conjunction with embodiments, but the scope of protection claimed by the present invention is not limited to the scope described in the embodiments.
实施例1Example 1
本发明的实施例提供了一种半水-二水湿法磷酸工艺生产高品质磷石膏的方法，包括以下步骤：The embodiment of the present invention provides a method for producing high-quality phosphogypsum by a semi-aqueous-dihydrate wet phosphoric acid process, comprising the following steps:
对磷矿浆进行脱水，得到水分在12％的磷矿粉；Dehydrating the phosphate slurry to obtain phosphate rock powder with a moisture content of 12%;
采用皮带输送该磷矿粉至预混槽，加入质量分数为20％磷酸进行预混合，使磷矿分解为磷酸一钙，搅拌生成预混料浆，控制预混料浆液相硫酸根质量分数＜0.1％；The phosphate rock powder is conveyed to a premixing tank by a belt, and 20% by mass of phosphoric acid is added for premixing to decompose the phosphate rock into monocalcium phosphate, and the premix slurry is generated by stirring, and the mass fraction of sulfate in the liquid phase of the premix slurry is controlled to be less than 0.1%;
预混料浆进入溶解槽，同时加入浓硫酸(质量分数96-98％)，在90-100℃下搅拌使磷矿进一步分解，生成料浆①，控制料浆①含固量在25-30％，料浆①中液相硫酸根质量分数在0.5-0.7％；The premixed slurry enters the dissolution tank, and concentrated sulfuric acid (mass fraction 96-98%) is added at the same time, and the phosphate rock is further decomposed by stirring at 90-100°C to generate slurry ①, and the solid content of slurry ① is controlled to be 25-30%, and the mass fraction of liquid sulfate in slurry ① is 0.5-0.7%;
料浆①进入结晶槽，同时加入浓硫酸(质量分数96-98％)，在90-100℃下搅拌促进磷石膏形成以半水硫酸钙结晶为主的混晶，搅拌生成料浆②，控制料浆②含固量在25-30％，控制料浆②固相磷石膏中半水硫酸钙含量在78-80％，二水硫酸钙含量在12-15％，控制料浆②中液相硫酸根质量分数在3.5-4.0％，P2O5浓度为38-42wt％；The slurry ① enters the crystallization tank, and concentrated sulfuric acid (mass fraction 96-98%) is added at the same time, and stirred at 90-100°C to promote the phosphogypsum to form mixed crystals mainly composed of hemihydrate calcium sulfate crystals, and stirred to form slurry ②, and the solid content of slurry ② is controlled to be 25-30%, the hemihydrate calcium sulfate content in the solid phase phosphogypsum of slurry ② is controlled to be 78-80%, the dihydrate calcium sulfate content is controlled to be 12-15%, the mass fraction of liquid phase sulfate in slurry ② is controlled to be 3.5-4.0%, and the P2O5 concentration is controlled to be 38-42wt%;
将料浆②过滤，回收得到38-42％的中间酸(产品磷酸)、半水返酸(半水返酸中含有质量分数为30-31％的磷酸及2.0-2.8％的硫酸)和磷石膏①，磷石膏①中半水硫酸钙含量在78-80％，二水硫酸钙含量在12-15％，总磷约为5-7％(其中含有水溶磷约为3-4％)，附着水为18-19％；半水返酸回用至磷矿粉中，用于预混分解得到磷酸一钙，同时控制预混料浆液相硫酸根质量分数＜0.1％；The slurry ② is filtered to recover 38-42% of the intermediate acid (product phosphoric acid), semi-hydrated return acid (the semi-hydrated return acid contains 30-31% of phosphoric acid and 2.0-2.8% of sulfuric acid by mass) and phosphogypsum ①, wherein the content of semi-hydrated calcium sulfate in the phosphogypsum ① is 78-80%, the content of dihydrated calcium sulfate is 12-15%, the total phosphorus is about 5-7% (including about 3-4% of water-soluble phosphorus), and the attached water is 18-19%; the semi-hydrated return acid is recycled to the phosphate rock powder for premixing and decomposition to obtain monocalcium phosphate, and the mass fraction of sulfate in the liquid phase of the premixed slurry is controlled to be less than 0.1%;
磷石膏①进入转化槽，同时加入适量浓硫酸，在温度为55-75℃下搅拌生成料浆③，控制料浆③含固量在30-35％，控制料浆③滤液硫酸根质量分数在6.0-7.0％，P2O5浓度为8-14wt％；Phosphogypsum① enters the conversion tank, and an appropriate amount of concentrated sulfuric acid is added at the same time, and stirred at a temperature of 55-75℃ to generate slurry③, the solid content of slurry③ is controlled to be 30-35%, the mass fraction of sulfate in the filtrate of slurry③ is controlled to be 6.0-7.0%, and the P2O5 concentration is 8-14wt%;
将料浆③过滤，得到滤液和磷石膏②，磷石膏②中半水硫酸钙含量在10-15％，二水硫酸钙含量在78-83％，水溶磷为0.6-1.0％，总磷为0.8-1.3％，附着水19-20％； Filter the slurry ③ to obtain a filtrate and phosphogypsum ②, wherein the phosphogypsum ② contains 10-15% calcium sulfate hemihydrate, 78-83% calcium sulfate dihydrate, 0.6-1.0% water-soluble phosphorus, 0.8-1.3% total phosphorus, and 19-20% attached water;
通过皮带输送磷石膏②至再浆槽，加水再浆生成料浆④，控制料浆④含固量为30-40％；The phosphogypsum ② is conveyed to the re-slurry tank by a belt, and water is added to re-slurry to form slurry ④, and the solid content of slurry ④ is controlled to be 30-40%;
对料浆④进行脱水处理，得到磷石膏③，磷石膏③中半水硫酸钙含量在10-15％，二水硫酸钙含量在78-83％，水溶磷为0.1-0.2％，总磷约为0.3-0.4％，附着水10-12％；Dehydrating the slurry ④ to obtain phosphogypsum ③, wherein the content of hemihydrate calcium sulfate in the phosphogypsum ③ is 10-15%, the content of dihydrate calcium sulfate is 78-83%, the water-soluble phosphorus is 0.1-0.2%, the total phosphorus is about 0.3-0.4%, and the attached water is 10-12%;
将磷石膏③和生石灰混合均匀，控制磷石膏初始pH值在6-8，陈化3天以上，得到磷石膏④，磷石膏④中半水硫酸钙完全转化为二水硫酸钙，二水硫酸钙含量91-93％，水溶磷＜0.1％，总磷约为0.2-0.5％，附着水＜9-11％，pH值在4-5。The phosphogypsum ③ and quicklime are uniformly mixed, the initial pH value of the phosphogypsum is controlled at 6-8, and aged for more than 3 days to obtain phosphogypsum ④, in which the calcium sulfate hemihydrate is completely converted into calcium sulfate dihydrate, the content of calcium sulfate dihydrate is 91-93%, the water-soluble phosphorus is less than 0.1%, the total phosphorus is about 0.2-0.5%, the attached water is less than 9-11%, and the pH value is 4-5.
实施例2Example 2
本发明的实施例提供了一种半水-二水湿法磷酸工艺生产高品质磷石膏的方法，包括以下步骤：The embodiment of the present invention provides a method for producing high-quality phosphogypsum by a semi-aqueous-dihydrate wet phosphoric acid process, comprising the following steps:
对磷矿浆进行脱水，得到水分在11％的磷矿粉；Dehydrating the phosphate slurry to obtain phosphate rock powder with a moisture content of 11%;
采用皮带输送该磷矿粉至预混槽，加入质量分数为20％磷酸进行预混合，使磷矿分解为磷酸一钙，搅拌生成预混料浆，控制预混料浆液相硫酸根质量分数＜0.1％；The phosphate rock powder is conveyed to a premixing tank by a belt, and 20% by mass of phosphoric acid is added for premixing to decompose the phosphate rock into monocalcium phosphate, and the premix slurry is generated by stirring, and the mass fraction of sulfate in the liquid phase of the premix slurry is controlled to be less than 0.1%;
预混料浆进入溶解槽，同时加入浓硫酸(质量分数96-98％)，在90-100℃下搅拌使磷矿进一步分解，生成料浆①，控制料浆①含固量在28-30％，料浆①中液相硫酸根质量分数在0.8-1.0％；The premixed slurry enters the dissolution tank, and concentrated sulfuric acid (mass fraction 96-98%) is added at the same time, and the phosphate rock is further decomposed by stirring at 90-100°C to generate slurry ①, and the solid content of slurry ① is controlled to be 28-30%, and the mass fraction of liquid sulfate in slurry ① is 0.8-1.0%;
料浆①进入结晶槽，同时加入浓硫酸(质量分数96-98％)，在90-100℃下搅拌促进磷石膏形成以半水硫酸钙结晶为主的混晶，搅拌生成料浆②，控制料浆②含固量在28-30％，控制料浆②固相磷石膏中半水硫酸钙含量在78-81％，二水硫酸钙含量在13-16％，控制料浆②中液相硫酸根质量分数在2.5-3.0％，P2O5浓度为38-42.5wt％；The slurry ① enters the crystallization tank, and concentrated sulfuric acid (mass fraction 96-98%) is added at the same time, and stirred at 90-100°C to promote the phosphogypsum to form mixed crystals mainly composed of hemihydrate calcium sulfate crystals, and stirred to form slurry ②, and the solid content of slurry ② is controlled to be 28-30%, the hemihydrate calcium sulfate content in the solid phase phosphogypsum of slurry ② is controlled to be 78-81%, the dihydrate calcium sulfate content is controlled to be 13-16%, the mass fraction of liquid phase sulfate in slurry ② is controlled to be 2.5-3.0%, and the P2O5 concentration is 38-42.5wt%;
将料浆②过滤，回收得到37.8-42％的中间酸(产品磷酸)、半水返酸(半水返酸中含有质量分数为20-29％的磷酸及2.0-2.6％的硫酸)和磷石膏①，磷石膏①中半水硫酸钙含量在78-81％，二水硫酸钙含量在13-16％，总磷约为4-7％(其中含有水溶磷约为3-5％)，附着水为18.5-19.5％；半水返酸回用至磷矿粉中，用于分解得到磷酸一钙，同时控制预混料浆液相硫酸根质量分数＜0.1％；The slurry ② is filtered to recover 37.8-42% of intermediate acid (product phosphoric acid), semi-hydrated return acid (the semi-hydrated return acid contains 20-29% by mass of phosphoric acid and 2.0-2.6% by mass of sulfuric acid) and phosphogypsum ①, wherein the content of semi-hydrated calcium sulfate in the phosphogypsum ① is 78-81%, the content of dihydrated calcium sulfate is 13-16%, the total phosphorus is about 4-7% (including about 3-5% of water-soluble phosphorus), and the attached water is 18.5-19.5%; the semi-hydrated return acid is recycled to the phosphate rock powder for decomposition to obtain monocalcium phosphate, and the mass fraction of sulfate in the liquid phase of the premixed slurry is controlled to be less than 0.1%;
磷石膏①进入转化槽，同时加入适量浓硫酸，在温度为55-75℃下搅拌生成料浆③，控制料浆③含固量在31-34％，控制料浆③固相磷石膏中半水硫酸钙含量在13-16％，二水硫酸钙含量在77-81％，控制料浆③液相硫酸根质量分数在7.0-8.0％，P2O5浓度为11-15wt％；The phosphogypsum ① enters the conversion tank, and an appropriate amount of concentrated sulfuric acid is added at the same time, and the slurry ③ is stirred at a temperature of 55-75°C to form the slurry ③, and the solid content of the slurry ③ is controlled to be 31-34%, the content of hemihydrate calcium sulfate in the solid phase phosphogypsum of the slurry ③ is controlled to be 13-16%, the content of dihydrate calcium sulfate is controlled to be 77-81%, the mass fraction of sulfate ion in the liquid phase of the slurry ③ is controlled to be 7.0-8.0%, and the concentration of P2O5 is controlled to be 11-15wt%;
将料浆③过滤，得到滤液和磷石膏②，磷石膏②中半水硫酸钙含量在13-15％，二水硫酸钙含量在77-81％，水溶磷为0.6-0.9％，总磷为0.8-1.1％，附着水19-20％；Filter the slurry ③ to obtain a filtrate and phosphogypsum ②, wherein the phosphogypsum ② contains 13-15% calcium sulfate hemihydrate, 77-81% calcium sulfate dihydrate, 0.6-0.9% water-soluble phosphorus, 0.8-1.1% total phosphorus, and 19-20% attached water;
通过皮带输送磷石膏②至再浆槽，加水再浆生成料浆④，控制料浆④含固量为32-40％； The phosphogypsum ② is conveyed to the re-slurry tank by a belt, and water is added to re-slurry to form slurry ④, and the solid content of slurry ④ is controlled to be 32-40%;
对料浆④进行脱水处理，得到磷石膏③，磷石膏③中半水硫酸钙含量在13-15％，二水硫酸钙含量在77-81％，水溶磷＜0.2％，总磷约为0.2-0.5％，附着水10-11.5％；Dehydrating the slurry ④ to obtain phosphogypsum ③, wherein the content of hemihydrate calcium sulfate in the phosphogypsum ③ is 13-15%, the content of dihydrate calcium sulfate is 77-81%, the water-soluble phosphorus is less than 0.2%, the total phosphorus is about 0.2-0.5%, and the attached water is 10-11.5%;
将磷石膏③和生石灰混合均匀，控制磷石膏初始pH值在6-8，陈化3天以上，得到磷石膏④，磷石膏④中半水硫酸钙完全转化为二水硫酸钙，二水硫酸钙含量92.2-93.5％，水溶磷＜0.1％，总磷约为0.2-0.5％，附着水10-11％，pH值在4-5。The phosphogypsum ③ and quicklime are uniformly mixed, the initial pH value of the phosphogypsum is controlled at 6-8, and aged for more than 3 days to obtain phosphogypsum ④, in which the calcium sulfate hemihydrate is completely converted into calcium sulfate dihydrate, the calcium sulfate dihydrate content is 92.2-93.5%, the water-soluble phosphorus is less than 0.1%, the total phosphorus is about 0.2-0.5%, the attached water is 10-11%, and the pH value is 4-5.
实施例3Example 3
本发明的实施例提供了一种半水-二水湿法磷酸工艺生产高品质磷石膏的方法，包括以下步骤：The embodiment of the present invention provides a method for producing high-quality phosphogypsum by a semi-aqueous-dihydrate wet phosphoric acid process, comprising the following steps:
对磷矿浆进行脱水，得到水分在12％的磷矿粉；Dehydrating the phosphate slurry to obtain phosphate rock powder with a moisture content of 12%;
采用皮带输送该磷矿粉至预混槽，加入质量分数为20％磷酸进行预混合，使磷矿分解为磷酸一钙，搅拌生成预混料浆，控制预混料浆液相硫酸根质量分数＜0.1％；The phosphate rock powder is conveyed to a premixing tank by a belt, and 20% by mass of phosphoric acid is added for premixing to decompose the phosphate rock into monocalcium phosphate, and the premix slurry is generated by stirring, and the mass fraction of sulfate in the liquid phase of the premix slurry is controlled to be less than 0.1%;
预混料浆进入溶解槽，同时加入浓硫酸(质量分数96-98％)，在90-100℃下搅拌使磷矿进一步分解，生成料浆①，控制料浆①含固量在25-30％，料浆①中液相硫酸根质量分数在1.0-1.2％；The premixed slurry enters the dissolution tank, and concentrated sulfuric acid (mass fraction 96-98%) is added at the same time, and the phosphate rock is further decomposed by stirring at 90-100°C to generate slurry ①, and the solid content of slurry ① is controlled to be 25-30%, and the mass fraction of liquid sulfate in slurry ① is 1.0-1.2%;
料浆①进入结晶槽，同时加入浓硫酸(质量分数96-98％)，在90-100℃下搅拌促进磷石膏形成以半水硫酸钙结晶为主的混晶，搅拌生成料浆②，控制料浆②含固量在25-30％，控制料浆②固相磷石膏中半水硫酸钙含量在75-81％，二水硫酸钙含量在12-18％，控制料浆②中液相硫酸根质量分数在2.5-3.5％，P2O5浓度为38-41wt％；The slurry ① enters the crystallization tank, and concentrated sulfuric acid (mass fraction 96-98%) is added at the same time, and stirred at 90-100°C to promote the phosphogypsum to form mixed crystals mainly composed of hemihydrate calcium sulfate crystals, and stirred to form slurry ②, and the solid content of slurry ② is controlled to be 25-30%, the hemihydrate calcium sulfate content in the solid phase phosphogypsum of slurry ② is controlled to be 75-81%, the dihydrate calcium sulfate content is controlled to be 12-18%, the mass fraction of liquid phase sulfate in slurry ② is controlled to be 2.5-3.5%, and the P2O5 concentration is 38-41wt%;
将料浆②过滤，回收得到37.5-41％的中间酸(产品磷酸)、半水返酸(半水返酸中含有质量分数为20-28％的磷酸及2.1-2.5％的硫酸)和磷石膏①，磷石膏①中半水硫酸钙含量在75-81％，二水硫酸钙含量在12-18％，总磷约为5-7％(其中含有水溶磷约为5-6％)，附着水19-20％；半水返酸回用至磷矿粉中，用于分解得到磷酸一钙，同时控制预混料浆液相硫酸根质量分数＜0.1％；The slurry ② is filtered to recover 37.5-41% of intermediate acid (product phosphoric acid), semi-hydrated return acid (the semi-hydrated return acid contains 20-28% by mass of phosphoric acid and 2.1-2.5% by mass of sulfuric acid) and phosphogypsum ①, wherein the content of semi-hydrated calcium sulfate in the phosphogypsum ① is 75-81%, the content of dihydrated calcium sulfate is 12-18%, the total phosphorus is about 5-7% (including about 5-6% of water-soluble phosphorus), and the attached water is 19-20%; the semi-hydrated return acid is recycled to the phosphate rock powder for decomposition to obtain monocalcium phosphate, and the mass fraction of sulfate in the liquid phase of the premixed slurry is controlled to be less than 0.1%;
磷石膏①进入转化槽，同时加入适量浓硫酸，在温度为55-75℃下搅拌生成料浆③，控制料浆③含固量在32-35％，控制料浆③固相磷石膏中半水硫酸钙含量在11-15％，二水硫酸钙含量在76-80％，控制料浆③液相硫酸根质量分数在5.0-7.0％，P2O5浓度为8-12wt％；The phosphogypsum ① enters the conversion tank, and an appropriate amount of concentrated sulfuric acid is added at the same time, and the slurry ③ is stirred at a temperature of 55-75°C, and the solid content of the slurry ③ is controlled to be 32-35%, the content of hemihydrate calcium sulfate in the solid phase phosphogypsum of the slurry ③ is controlled to be 11-15%, the content of dihydrate calcium sulfate is controlled to be 76-80%, the mass fraction of sulfate ion in the liquid phase of the slurry ③ is controlled to be 5.0-7.0%, and the concentration of P2O5 is controlled to be 8-12wt%;
将料浆③过滤，得到滤液和磷石膏②，磷石膏②中半水硫酸钙含量在10-15％，二水硫酸钙含量在76-80％，水溶磷为0.7-1.0％，总磷为0.8-1.3％，附着水19-20％；Filter the slurry ③ to obtain a filtrate and phosphogypsum ②, wherein the phosphogypsum ② contains 10-15% calcium sulfate hemihydrate, 76-80% calcium sulfate dihydrate, 0.7-1.0% water-soluble phosphorus, 0.8-1.3% total phosphorus, and 19-20% attached water;
通过皮带输送磷石膏②至再浆槽，加水再浆生成料浆④，控制料浆④含固量为32-40％；The phosphogypsum ② is conveyed to the re-slurry tank by a belt, and water is added to re-slurry to form slurry ④, and the solid content of slurry ④ is controlled to be 32-40%;
对料浆④进行脱水处理，得到磷石膏③，磷石膏③中半水硫酸钙含量在10-15％，二水硫酸 钙含量在76-81％，水溶磷＜0.2％，总磷约为0.2-0.5％，附着水11-12％；The slurry ④ is dehydrated to obtain phosphogypsum ③, wherein the content of hemihydrate calcium sulfate in the phosphogypsum ③ is 10-15%, and the content of dihydrate calcium sulfate is 10-15%. The calcium content is 76-81%, water-soluble phosphorus is less than 0.2%, total phosphorus is about 0.2-0.5%, and attached water is 11-12%;
将磷石膏③和生石灰混合均匀，控制磷石膏初始pH值在6-8，陈化3天以上，得到磷石膏④，磷石膏④中半水硫酸钙完全转化为二水硫酸钙，二水硫酸钙含量90.6-91.5％，水溶磷＜0.1％，总磷约为0.2-0.5％，附着水9-11％，pH值在4-5。The phosphogypsum ③ and quicklime are uniformly mixed, the initial pH value of the phosphogypsum is controlled at 6-8, and aged for more than 3 days to obtain phosphogypsum ④, in which the calcium sulfate hemihydrate is completely converted into calcium sulfate dihydrate, the calcium sulfate dihydrate content is 90.6-91.5%, the water-soluble phosphorus is less than 0.1%, the total phosphorus is about 0.2-0.5%, the attached water is 9-11%, and the pH value is 4-5.
实施例4Example 4
与本申请实施例1相比，不加质量浓度为20％的稀磷酸进行预混，直接将脱水后的磷矿粉加入浓硫酸的质量分数为96-98％，加入浓硫酸后在温度为90-100℃下搅拌得到料浆①。则最终得到的磷石膏③中半水硫酸钙含量在10-20％，二水硫酸钙含量在70-80％，水溶磷＜0.2％，总磷约为0.5-0.8％，附着水＜12％；Compared with Example 1 of the present application, the dehydrated phosphate rock powder is directly added with concentrated sulfuric acid at a mass fraction of 96-98% without adding 20% dilute phosphoric acid for premixing, and the concentrated sulfuric acid is added and stirred at a temperature of 90-100°C to obtain slurry ①. The final phosphogypsum ③ has a hemihydrate calcium sulfate content of 10-20%, a dihydrate calcium sulfate content of 70-80%, water-soluble phosphorus <0.2%, total phosphorus of about 0.5-0.8%, and attached water <12%;
将磷石膏③和生石灰混合均匀，控制磷石膏初始pH值在6-8，陈化3天以上，得到磷石膏④，磷石膏④中半水硫酸钙完全转化为二水硫酸钙，二水硫酸钙含量90.8％，水溶磷＜0.1％，总磷约为0.5-0.8％，附着水9-11％，pH值在4-5。The phosphogypsum ③ and quicklime are uniformly mixed, the initial pH value of the phosphogypsum is controlled at 6-8, and aged for more than 3 days to obtain phosphogypsum ④, in which the calcium sulfate hemihydrate is completely converted into calcium sulfate dihydrate, the content of calcium sulfate dihydrate is 90.8%, the water-soluble phosphorus is less than 0.1%, the total phosphorus is about 0.5-0.8%, the attached water is 9-11%, and the pH value is 4-5.
实施例5Example 5
与本申请实施例1相比，预混料浆进入溶解槽，同时加入浓硫酸(质量分数96-98％)使磷矿进一步分解，停留4小时生成料浆①，控制料浆①液相硫酸根质量分数在1.5％，控制料浆①温度在90-100℃，控制料浆①含固量在37％；Compared with Example 1 of the present application, the premixed slurry enters the dissolution tank, and concentrated sulfuric acid (mass fraction 96-98%) is added to further decompose the phosphate rock, and the slurry is kept for 4 hours to generate slurry ①, and the mass fraction of sulfate ions in the liquid phase of slurry ① is controlled at 1.5%, the temperature of slurry ① is controlled at 90-100° C., and the solid content of slurry ① is controlled at 37%;
则最终得到的磷石膏③中半水硫酸钙含量在15-27％，二水硫酸钙含量在60-77％，水溶磷＜0.2％，总磷约为0.4-1.1％(波动范围较大，不稳定)，附着水＜12％；The final phosphogypsum ③ has a hemihydrate calcium sulfate content of 15-27%, a dihydrate calcium sulfate content of 60-77%, water-soluble phosphorus <0.2%, total phosphorus of about 0.4-1.1% (with a large fluctuation range and instability), and attached water <12%;
将磷石膏③和生石灰混合均匀，控制磷石膏初始pH值在6-8，陈化七天以上，得到磷石膏④，磷石膏④中半水硫酸钙完全转化为二水硫酸钙，二水硫酸钙含量89.5％，水溶磷＜0.1％，总磷约为0.4-1.1％，附着水8-10％，pH值在4-5。The phosphogypsum ③ and quicklime are mixed evenly, the initial pH value of the phosphogypsum is controlled at 6-8, and aged for more than seven days to obtain phosphogypsum ④, in which the calcium sulfate hemihydrate is completely converted into calcium sulfate dihydrate, the content of calcium sulfate dihydrate is 89.5%, the water-soluble phosphorus is less than 0.1%, the total phosphorus is about 0.4-1.1%, the attached water is 8-10%, and the pH value is 4-5.
实施例6Example 6
与本申请实施例1相比，料浆①进入结晶槽，同时加入浓硫酸(质量分数96-98％)促进磷石膏形成以半水硫酸钙结晶为主的混晶，停留3小时生成料浆②，控制料浆②液相硫酸根质量分数在1.2％，P2O5浓度为41wt％，控制料浆②温度在90-100℃，控制料浆③含固量在36％；Compared with Example 1 of the present application, slurry ① enters the crystallization tank, and concentrated sulfuric acid (mass fraction 96-98%) is added to promote the phosphogypsum to form mixed crystals mainly composed of hemihydrate calcium sulfate crystals, and stays for 3 hours to generate slurry ②, and the mass fraction of sulfate ions in the liquid phase of slurry ② is controlled to be 1.2%, the concentration of P2O5 is 41wt%, the temperature of slurry ② is controlled to be 90-100°C, and the solid content of slurry ③ is controlled to be 36%;
则最终得到的磷石膏③中半水硫酸钙含量在5-18％，二水硫酸钙含量在68-82％，水溶磷约为0.8-1.5％，总磷约为1.1-1.9％，附着水＜12％；The final phosphogypsum ③ has a content of calcium sulfate hemihydrate of 5-18%, a content of calcium sulfate dihydrate of 68-82%, water-soluble phosphorus of about 0.8-1.5%, total phosphorus of about 1.1-1.9%, and attached water of <12%;
将磷石膏③和生石灰混合均匀，控制磷石膏初始pH值在6-8，陈化七天以上，得到磷石膏④，磷石膏④中半水硫酸钙完全转化为二水硫酸钙，二水硫酸钙含量91.5％，水溶磷＜ 0.2％，总磷约为1.0-1.9％，附着水8.5-10％，pH值在3.2-5.6。The phosphogypsum ③ and quicklime are mixed evenly, the initial pH value of the phosphogypsum is controlled at 6-8, and the phosphogypsum is aged for more than seven days to obtain phosphogypsum ④, and the hemihydrate calcium sulfate in the phosphogypsum ④ is completely converted into dihydrate calcium sulfate, the dihydrate calcium sulfate content is 91.5%, and the water-soluble phosphorus is less than 0.2%, total phosphorus is about 1.0-1.9%, attached water is 8.5-10%, and the pH value is 3.2-5.6.
实施例7Example 7
与本申请实施例1相比，磷石膏①进入转化槽，同时加入适量浓硫酸，停留1.5小时，生成料浆③，控制料浆③液相硫酸根质量分数在11.5％，P2O5浓度为15wt％，控制料浆③温度在80℃，控制料浆③含固量在27％；Compared with Example 1 of the present application, phosphogypsum ① enters the conversion tank, and an appropriate amount of concentrated sulfuric acid is added at the same time, and the mixture stays for 1.5 hours to generate slurry ③, and the mass fraction of sulfate ions in the liquid phase of slurry ③ is controlled to be 11.5%, the concentration of P2O5 is 15wt%, the temperature of slurry ③ is controlled to be 80°C, and the solid content of slurry ③ is controlled to be 27%;
则最终得到的磷石膏③中半水硫酸钙含量在17-26％，二水硫酸钙含量在65-75％，水溶磷约为0.4-0.7％，总磷约为0.7-1.0％，附着水＜12％；The final phosphogypsum ③ has a content of calcium sulfate hemihydrate of 17-26%, a content of calcium sulfate dihydrate of 65-75%, a water-soluble phosphorus of about 0.4-0.7%, a total phosphorus of about 0.7-1.0%, and an adhering water content of <12%;
将磷石膏③和生石灰混合均匀，控制磷石膏初始pH值在6-8，陈化七天以上，得到磷石膏④，磷石膏④中半水硫酸钙完全转化为二水硫酸钙，二水硫酸钙含量92.6％，水溶磷＜0.1％，总磷约为0.7-1.0％，附着水8-10％，pH值在3.8-4.7。 The phosphogypsum ③ and quicklime are uniformly mixed, the initial pH value of the phosphogypsum is controlled at 6-8, and aged for more than seven days to obtain phosphogypsum ④, in which the calcium sulfate hemihydrate is completely converted into calcium sulfate dihydrate, the content of calcium sulfate dihydrate is 92.6%, the water-soluble phosphorus is less than 0.1%, the total phosphorus is about 0.7-1.0%, the attached water is 8-10%, and the pH value is 3.8-4.7.

Claims (10)

  1. 一种半水-二水湿法磷酸工艺生产磷石膏的方法，其特征在于，包括以下步骤：A method for producing phosphogypsum by a semi-aqueous-dihydrate wet phosphoric acid process, characterized in that it comprises the following steps:
    (1)对磷矿浆进行脱水，得到磷矿粉；(1) dehydrating the phosphate slurry to obtain phosphate rock powder;
    (2)将磷矿粉加入浓硫酸进行溶解，得到料浆一；(2) adding concentrated sulfuric acid to dissolve phosphate rock powder to obtain slurry 1;
    (3)将料浆一加入浓硫酸进行结晶，得到料浆二；(3) adding concentrated sulfuric acid to slurry 1 for crystallization to obtain slurry 2;
    (4)将料浆二过滤得到中间酸、半水返酸和磷石膏粗品；(4) filtering the slurry II to obtain intermediate acid, semi-hydrated acid and crude phosphogypsum;
    (5)将磷石膏粗品加入浓硫酸进行转化，得到料浆三；(5) adding concentrated sulfuric acid to the crude phosphogypsum for conversion to obtain slurry three;
    (6)将料浆三经过滤、加水再浆、脱水后得到磷石膏；(6) filtering the slurry, adding water to re-slurry, and dehydrating to obtain phosphogypsum;
    (7)将磷石膏加生石灰混合均匀，陈化后得到磷石膏精品。(7) Mix phosphogypsum and quicklime evenly, and obtain fine phosphogypsum after aging.
  2. 根据权利要求1所述的半水-二水湿法磷酸工艺生产磷石膏的方法，其特征在于，所述的步骤(1)中磷矿粉经脱水后含水量低于12％；磷矿粉加入质量浓度为20-35％的磷酸进行预混，得到含磷酸一钙的料浆；The method for producing phosphogypsum by a semi-aqueous-dihydrate wet phosphoric acid process according to claim 1, characterized in that the water content of the phosphate rock powder after dehydration in the step (1) is less than 12%; phosphoric acid having a mass concentration of 20-35% is added to the phosphate rock powder for premixing to obtain a slurry containing monocalcium phosphate;
    所述的步骤(2)中浓硫酸的质量分数为96-98％，加入浓硫酸后在温度为90-100℃下搅拌得到料浆一。The mass fraction of concentrated sulfuric acid in step (2) is 96-98%. After adding concentrated sulfuric acid, the mixture is stirred at a temperature of 90-100° C. to obtain slurry 1.
  3. 根据权利要求2所述的半水-二水湿法磷酸工艺生产磷石膏的方法，其特征在于，所述的步骤(3)中浓硫酸的质量分数为96-98％，加入浓硫酸后在温度为90-100℃下搅拌得到料浆二。The method for producing phosphogypsum by a semi-aqueous-dihydrate wet phosphoric acid process according to claim 2, characterized in that the mass fraction of concentrated sulfuric acid in step (3) is 96-98%, and after adding concentrated sulfuric acid, stirring is carried out at a temperature of 90-100°C to obtain slurry 2.
  4. 根据权利要求3所述的半水-二水湿法磷酸工艺生产磷石膏的方法，其特征在于，所述步骤(4)的中间酸为磷酸，磷酸质量分数为36-43％；所述的半水返酸中包括质量分数为20-35％的磷酸及质量分数为2-4％的硫酸；所述的磷石膏粗品中包括质量分数在75-81％半水硫酸钙，质量分数在12-18％二水硫酸钙，水溶磷为3-6％，总磷为4-7％，附着水＜20％。The method for producing phosphogypsum by the semi-hydrated-dihydrate wet phosphoric acid process according to claim 3 is characterized in that the intermediate acid in step (4) is phosphoric acid, and the mass fraction of phosphoric acid is 36-43%; the semi-hydrated return acid includes phosphoric acid with a mass fraction of 20-35% and sulfuric acid with a mass fraction of 2-4%; the crude phosphogypsum includes calcium sulfate hemihydrate with a mass fraction of 75-81%, calcium sulfate dihydrate with a mass fraction of 12-18%, water-soluble phosphorus with a mass fraction of 3-6%, total phosphorus with a mass fraction of 4-7%, and attached water <20%.
  5. 根据权利要求4所述的半水-二水湿法磷酸工艺生产磷石膏的方法，其特征在于，所述的半水返酸回用至步骤(2)中，对磷矿粉进行预混使其分解成含磷酸一钙的料浆，同时控制料浆中液相硫酸根质量分数＜0.1％。The method for producing phosphogypsum by a semi-aqueous-dihydrate wet phosphoric acid process according to claim 4 is characterized in that the semi-aqueous acid is recycled to step (2), the phosphate rock powder is premixed to decompose it into a slurry containing monocalcium phosphate, and the mass fraction of liquid sulfate in the slurry is controlled to be less than 0.1%.
  6. 根据权利要求5所述的半水-二水湿法磷酸工艺生产磷石膏的方法，其特征在于，所述步骤(5)中加入浓硫酸，在55-75℃下搅拌得到料浆三。The method for producing phosphogypsum by a semi-aqueous-dihydrate wet phosphoric acid process according to claim 5, characterized in that concentrated sulfuric acid is added in step (5) and stirred at 55-75°C to obtain slurry three.
  7. 根据权利要求5所述的半水-二水湿法磷酸工艺生产磷石膏的方法，其特征在于，所述步骤(6)中得到的磷石膏中半水硫酸钙质量分数为10-20％，二水硫酸钙质量分数为71-81％，水溶磷＜0.2％，总磷为0.2-0.5％，附着水＜12％。The method for producing phosphogypsum by a semi-hydrated-dihydrate wet phosphoric acid process according to claim 5, characterized in that the mass fraction of calcium sulfate semi-hydrate in the phosphogypsum obtained in the step (6) is 10-20%, the mass fraction of calcium sulfate dihydrate is 71-81%, the water-soluble phosphorus is less than 0.2%, the total phosphorus is 0.2-0.5%, and the attached water is less than 12%.
  8. 根据权利要求7所述的半水-二水湿法磷酸工艺生产磷石膏的方法，其特征在于，所述的步骤(7)中磷石膏加生石灰混合均匀，控制磷石膏初始PH值在6-12，陈化3天以上得到 磷石膏精品，磷石膏精品中二水硫酸钙质量分数＞90％，水溶磷＜0.1％，总磷为0.2-0.5％，附着水＜12％，PH值4-11。The method for producing phosphogypsum by semi-aqueous-dihydrate wet phosphoric acid process according to claim 7, characterized in that in the step (7), the phosphogypsum is mixed with quicklime evenly, the initial pH value of the phosphogypsum is controlled to be 6-12, and the phosphogypsum is aged for more than 3 days to obtain High-quality phosphogypsum, in which the mass fraction of calcium sulfate dihydrate is greater than 90%, water-soluble phosphorus is less than 0.1%, total phosphorus is 0.2-0.5%, attached water is less than 12%, and pH value is 4-11.
  9. 根据权利要求1-8任一项所述的半水-二水湿法磷酸工艺生产的磷石膏。Phosphogypsum produced by the semi-aqueous-dihydrate wet phosphoric acid process according to any one of claims 1 to 8.
  10. 根据权利要求1-8任一项所述的半水-二水湿法磷酸工艺生产的含半水硫酸钙及二水硫酸钙双晶态磷石膏，其中半水硫酸钙含量在10-20％，二水硫酸钙含量在71-81％，水溶磷为0.6-1.0％，总磷为0.8-1.3％，附着水＜20％；The bicrystalline phosphogypsum containing calcium sulfate hemihydrate and calcium sulfate dihydrate produced by the hemihydrate-dihydrate wet phosphoric acid process according to any one of claims 1 to 8, wherein the content of calcium sulfate hemihydrate is 10-20%, the content of calcium sulfate dihydrate is 71-81%, the water-soluble phosphorus is 0.6-1.0%, the total phosphorus is 0.8-1.3%, and the attached water is less than 20%;
    或者半水-二水湿法磷酸工艺生产的含半水硫酸钙含量在10-20％，二水硫酸钙含量在71-81％，水溶磷＜0.2％，总磷为0.2-0.5％，附着水＜12％。 Or the hemihydrate-dihydrate wet phosphoric acid process contains 10-20% hemihydrate calcium sulfate, 71-81% dihydrate calcium sulfate, less than 0.2% water-soluble phosphorus, 0.2-0.5% total phosphorus, and less than 12% attached water.
PCT/CN2023/089825 2022-10-25 2023-04-21 Method for producing phosphogypsum by hemihydrate-dihydrate wet process phosphoric acid process WO2024087546A1 (en)

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CN115583666B (en) * 2022-10-25 2024-03-29 宜都兴发化工有限公司 Method for producing phosphogypsum by semi-water-dihydrate wet phosphoric acid process
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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4452770A (en) * 1981-12-14 1984-06-05 United States Gypsum Company Phosphoanhydrite process
CN105948009A (en) * 2016-04-28 2016-09-21 昆明川金诺化工股份有限公司 Energy-saving semihydrate-dihydrate wet-process phosphoric acid and white gypsum coproduction method
CN106431034A (en) * 2016-08-31 2017-02-22 贵州川恒化工股份有限公司 Method for producing building gypsum powder from semi-hydrate phosphogypsum
CN109734344A (en) * 2019-03-05 2019-05-10 昆明川金诺化工股份有限公司 A method of cement retarder is prepared using half water ardealite
CN112194109A (en) * 2020-09-30 2021-01-08 湖北宜化松滋肥业有限公司 Method for producing phosphoric acid and coproducing gypsum by semi-water-dihydrate wet-process phosphoric acid process
CN115583666A (en) * 2022-10-25 2023-01-10 宜都兴发化工有限公司 Method for producing phosphogypsum by semi-water-dihydrate wet-process phosphoric acid process

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4452770A (en) * 1981-12-14 1984-06-05 United States Gypsum Company Phosphoanhydrite process
CN105948009A (en) * 2016-04-28 2016-09-21 昆明川金诺化工股份有限公司 Energy-saving semihydrate-dihydrate wet-process phosphoric acid and white gypsum coproduction method
CN106431034A (en) * 2016-08-31 2017-02-22 贵州川恒化工股份有限公司 Method for producing building gypsum powder from semi-hydrate phosphogypsum
CN109734344A (en) * 2019-03-05 2019-05-10 昆明川金诺化工股份有限公司 A method of cement retarder is prepared using half water ardealite
CN112194109A (en) * 2020-09-30 2021-01-08 湖北宜化松滋肥业有限公司 Method for producing phosphoric acid and coproducing gypsum by semi-water-dihydrate wet-process phosphoric acid process
CN115583666A (en) * 2022-10-25 2023-01-10 宜都兴发化工有限公司 Method for producing phosphogypsum by semi-water-dihydrate wet-process phosphoric acid process

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