WO2024021234A1 - 磷石膏净化提纯制备硫酸钙晶须的方法 - Google Patents

磷石膏净化提纯制备硫酸钙晶须的方法 Download PDF

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WO2024021234A1
WO2024021234A1 PCT/CN2022/117484 CN2022117484W WO2024021234A1 WO 2024021234 A1 WO2024021234 A1 WO 2024021234A1 CN 2022117484 W CN2022117484 W CN 2022117484W WO 2024021234 A1 WO2024021234 A1 WO 2024021234A1
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solid
phosphogypsum
calcium sulfate
temperature
filtrate
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French (fr)
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余海军
李爱霞
谢英豪
张学梅
李长东
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广东邦普循环科技有限公司
湖南邦普循环科技有限公司
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    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B7/00—Single-crystal growth from solutions using solvents which are liquid at normal temperature, e.g. aqueous solutions
    • C30B7/14—Single-crystal growth from solutions using solvents which are liquid at normal temperature, e.g. aqueous solutions the crystallising materials being formed by chemical reactions in the solution
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/46—Sulfur-, selenium- or tellurium-containing compounds
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/60—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape characterised by shape
    • C30B29/62—Whiskers or needles

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  • the invention belongs to the technical field of phosphogypsum treatment in phosphorus chemical industry, and specifically relates to a method for purifying and purifying phosphogypsum to prepare calcium sulfate whiskers.
  • Phosphogypsum is a solid waste residue discharged by phosphorus chemical companies using wet processes to produce phosphoric acid.
  • the main component is calcium sulfate dihydrate.
  • it also contains undecomposed phosphate rock, organic matter, silica, fluoride, phosphate, sulfuric acid, and a small amount of Impurities such as metals (potassium, sodium, iron, aluminum) and heavy metals.
  • metals potential, sodium, iron, aluminum
  • Phosphogypsum is rich in calcium and sulfur and is a valuable resource. Modified phosphogypsum can be used to replace increasingly scarce natural gypsum resources. Therefore, from the perspective of environmental protection and resource utilization, the treatment and utilization of phosphogypsum waste residue is urgent.
  • the Chinese patent application number 200410021766.4 discloses a method for producing building decoration materials and wall materials using phosphogypsum
  • the Chinese patent application number 200410081601.6 discloses profiles produced using phosphogypsum and its preparation method
  • the Chinese patent 200410060727.5 discloses the application of lime in the harmless treatment of phosphogypsum.
  • the Chinese patent application number 201110188922.6 discloses the steps of cleaning, neutralizing, dehydrating, calcining, and packaging phosphogypsum to achieve harmless treatment; these technical solutions for treating phosphogypsum require high investment and are difficult to implement. It is relatively difficult and the resulting products can only be used as building materials.
  • Calcium sulfate whiskers are fibrous single crystals of anhydrous calcium sulfate, also known as gypsum whiskers, which are needle-like white fibers. Calcium sulfate whiskers have the advantages of high strength, resistance to chemical corrosion, high temperature resistance, good toughness, and strong affinity with rubber and other polymers. They can be widely used in rubber, plastics, friction materials, coatings, paints, papermaking, catalysis, and conductive powders. and other fields of new materials.
  • the current production methods in various countries around the world not only have high production costs, complicated procedures, but also cause heavy pollution. Therefore, using industrial waste phosphogypsum to prepare gypsum whiskers and studying a cheap and simple preparation method for gypsum whiskers are not only environmentally friendly, but also have excellent socioeconomic benefits.
  • the present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. For this reason, the present invention proposes a method for purifying and purifying phosphogypsum to prepare calcium sulfate whiskers.
  • a method for purifying and purifying phosphogypsum to prepare calcium sulfate whiskers includes the following steps:
  • S1 Mix phosphogypsum and water to make a slurry, add alkali to adjust the pH of the slurry, and separate the solid and liquid to obtain the filter residue;
  • step S5 The material after the hydrothermal reaction in step S4 is cooled and then layered, and the bottom solid is taken to obtain the calcium sulfate whisker.
  • step S1 the mass ratio of the phosphogypsum to water is 1: (1-2).
  • the base is at least one of sodium hydroxide or ammonia water.
  • step S1 the pH of the slurry is adjusted to 7-8.
  • step S2 air flow drying is used for drying, the inlet air temperature is controlled to 400-450°C, the air outlet temperature is 150-180°C, the air inlet speed is 15-20m/s, and the residence time is for 5-10s.
  • step S2 the calcination process is: blowing in hot air, controlling the inlet air temperature to 600-800°C, the outlet air temperature to 400-450°C, and the air inlet speed to 15-20m/ s, the residence time is 5-10s.
  • step S3 the concentration of ethylenediaminetetraacetate in the aqueous solution is 0.5-1.0 mol/L, and the solid-liquid ratio of the calcined material and the aqueous solution is 100-180g/L .
  • the ethylenediaminetetraacetate is selected from tetrasodium ethylenediaminetetraacetate.
  • step S3 the temperature of the heated leaching is 80-95°C.
  • step S3 the heating leaching is performed under stirring at a rotation speed of 100-300 r/min.
  • step S3 the heating leaching time is 4-8 hours.
  • step S4 the added amount of nano-calcium carbonate is 15-30g/L filtrate.
  • step S4 the particle size of the nano-calcium carbonate is 1-100 nm.
  • step S4 the addition amount of the surfactant is 3-8g/L filtrate.
  • the surfactant is a sulfate ester salt and/or a sulfonate salt.
  • the sulfate ester salt is selected from at least one of fatty alcohol sulfate, secondary alkyl sulfate, fatty alcohol polyoxyethylene ether sulfate ester salt or sulfate ester salt of fatty acid derivatives;
  • the sulfonate salt is selected from From at least one of alkyl benzene sulfonate, alkyl naphthalene sulfonate, alkyl sulfonate, petroleum sulfonate or lignin sulfonate.
  • step S4 the added amount of sulfuric acid is 4.2-4.5 times the molar amount of ethylenediaminetetraacetate.
  • step S4 the temperature of the hydrothermal reaction is 120-150°C. Further, the hydrothermal reaction time is 3-6 hours.
  • the temperature after cooling is 20-40°C.
  • the temperature after cooling is 20-28°C.
  • step S5 the layering is divided into three layers.
  • the upper layer is a mixture of foam and ethylenediaminetetraacetic acid solid.
  • the mixture in the upper layer is solid-liquid separated to obtain ethylenediaminetetraacetic acid.
  • ethylenediaminetetraacetic acid and alkali are mixed to prepare ethylenediaminetetraacetic acid salt, which is used again in step S3.
  • the base is selected from sodium hydroxide.
  • step S5 also includes: washing the bottom solid with water and drying at 100-120°C for 1-2 hours to obtain the calcium sulfate whiskers.
  • the acidic substances in the phosphogypsum are first neutralized by slurrying with alkaline solution, and then dried, calcined and dehydrated.
  • the metal impurities in the gypsum are made to exist in the form of insoluble oxides to avoid the introduction of impurity metals in the subsequent leaching process.
  • ethylenediaminetetraacetate is used to react with calcium sulfate in phosphogypsum to generate soluble chelated calcium, which is then hydrothermally reacted with sulfuric acid to recrystallize calcium sulfate. , and generate ethylenediaminetetraacetic acid and sulfate.
  • the reaction principle is as follows (taking tetrasodium ethylenediaminetetraacetate as an example):
  • nano-calcium carbonate is used as an induced crystal seed. Under the action of sulfuric acid, calcium sulfate whiskers are continuously generated. At the same time, the induced seed crystal nano-calcium carbonate is continuously dissolved and generates carbon dioxide. In the presence of surfactant, Under the action, carbon dioxide forms bubbles, and the newly generated and low-density ethylenediaminetetraacetic acid floats, while the heavier calcium sulfate sinks to the bottom, and the middle layer is a sulfate solution, thereby realizing calcium sulfate, EDTA, sulfate The three solutions are separated to obtain relatively pure calcium sulfate whiskers, with a purity of more than 99%.
  • the EDTA produced at the end of the reaction reacts with alkali and is used as a leaching agent to leach phosphogypsum, thus avoiding the consumption of EDTA.
  • the present invention obtains high-value calcium sulfate whiskers by leaching and recrystallizing phosphogypsum, allowing the solid waste phosphogypsum to be further developed and utilized, achieving environmental protection and increasing value.
  • Figure 1 is a process flow diagram of Embodiment 1 of the present invention.
  • Figure 2 is a SEM image of calcium sulfate whiskers prepared in Example 1 of the present invention.
  • a method for purifying and purifying phosphogypsum to prepare calcium sulfate whiskers Refer to Figure 1. The specific process is:
  • Step 1 Mix phosphogypsum and primary water at a mass ratio of 1:2, then add sodium hydroxide to adjust the slurry, and control the pH of the slurry to 8;
  • Step 2 solid-liquid separation, the obtained filtrate enters the wastewater treatment system, and the obtained filter cake is placed in a pulse airflow dryer for drying.
  • the inlet air temperature is controlled to 450°C, the outlet air temperature is 180°C, and the air inlet speed is 20m/s.
  • the residence time is 5s;
  • Step 3 Place the dried material in a calcining furnace for calcination, blow in high-temperature hot air, control the inlet air temperature to 800°C, the outlet air temperature to 450°C, the air inlet speed to 20m/s, and the residence time to 5s;
  • Step 4 Add the calcined phosphogypsum to an aqueous solution of tetrasodium ethylenediaminetetraacetate of 1.0 mol/L according to a solid-to-liquid ratio of 170g/L for leaching.
  • the reaction temperature is controlled to 95°C and the stirring speed is 300r/ min, the leaching time is 4h;
  • Step 5 perform suction filtration while hot, separate solid and liquid, and obtain filtrate
  • Step 6 Place the filtrate in the reaction kettle, add nanometer calcium carbonate with a particle size of 1-100nm and 8g/L sodium lauryl sulfate according to a solid-liquid ratio of 30g/L, and add tetrasodium ethylenediaminetetraacetate. 4.5 times the molar amount of sulfuric acid, seal it, control the temperature in the kettle to 150°C, and the reaction time to 3 hours;
  • Step 7 After the reaction is completed, the reaction kettle is cooled to room temperature. The materials in the kettle are divided into three layers, and solid-liquid separation is performed. The obtained filtrate is sodium sulfate solution, and the upper layer is a mixture of foam and solid. After solid-liquid separation, the solid obtained is ethyl alcohol. Diaminetetraacetic acid, add 4 times the molar amount of sodium hydroxide to prepare tetrasodium ethylenediaminetetraacetate, and reuse it in step 4. The obtained bottom solid is washed with deionized water and dried at 120°C for 1 hour to obtain sulfuric acid. Calcium whiskers, their morphology is shown in Figure 2.
  • a method for purifying and purifying phosphogypsum to prepare calcium sulfate whiskers is:
  • Step 1 Mix phosphogypsum and primary water at a mass ratio of 1:1.5, then add ammonia water to adjust the slurry, and control the pH of the slurry to 7.5;
  • Step 2 solid-liquid separation, the obtained filtrate enters the wastewater treatment system, and the obtained filter cake is placed in a pulse airflow dryer for drying.
  • the inlet air temperature is controlled to 430°C, the outlet air temperature is 165°C, and the air inlet speed is 18m/s.
  • the residence time is 8s;
  • Step 3 Place the dried material into a calcining furnace for calcination, blow in high-temperature hot air, control the inlet air temperature to 600°C, the outlet air temperature to 430°C, the air inlet speed to 18m/s, and the residence time to 8s;
  • Step 4 Add the calcined phosphogypsum to a 0.5 mol/L aqueous solution of tetrasodium ethylenediaminetetraacetate according to a solid-to-liquid ratio of 80g/L for leaching.
  • the reaction temperature is controlled to 90°C and the stirring speed is 200r/ min, the leaching time is 6h;
  • Step 5 perform suction filtration while hot, separate solid and liquid, and obtain filtrate
  • Step 6 Place the filtrate in the reaction kettle, add nanometer calcium carbonate with a particle size of 1-100nm and 5g/L sodium hexadecyl sulfonate according to a solid-liquid ratio of 20g/L, and add ethylenediaminetetraacetic acid tetraacetic acid. 4.3 times the molar amount of sodium sulfuric acid, seal it, control the temperature in the kettle to 135°C, and the reaction time to 5 hours;
  • Step 7 After the reaction is completed, the reaction kettle is cooled to room temperature. The materials in the kettle are divided into three layers, and solid-liquid separation is performed. The obtained filtrate is sodium sulfate solution, and the upper layer is a mixture of foam and solid. After solid-liquid separation, the solid obtained is ethyl alcohol. Diaminetetraacetic acid, add 4 times the molar amount of sodium hydroxide to prepare tetrasodium ethylenediaminetetraacetate, and reuse it in step 4. The obtained bottom solid is washed with deionized water and dried at 110°C for 1.5h. Calcium sulfate whiskers.
  • a method for purifying and purifying phosphogypsum to prepare calcium sulfate whiskers is:
  • Step 1 Mix phosphogypsum and primary water at a mass ratio of 1:1, then add ammonia water to adjust the slurry, and control the pH of the slurry to 7;
  • Step 2 solid-liquid separation, the obtained filtrate enters the wastewater treatment system, and the obtained filter cake is placed in a pulse air flow dryer for drying.
  • the inlet air temperature is controlled to 400°C, the outlet air temperature is 150°C, and the air inlet speed is 15m/s.
  • the residence time is 10s;
  • Step 3 Place the dried material in a calcining furnace for calcination, blow in high-temperature hot air, control the inlet air temperature to 600°C, the outlet air temperature to 400°C, the air inlet speed to 15m/s, and the residence time to 10s;
  • Step 4 Add the calcined phosphogypsum to a 0.1 mol/L aqueous solution of tetrasodium ethylenediaminetetraacetate according to a solid-to-liquid ratio of 17g/L for leaching.
  • the reaction temperature is controlled to 80°C and the stirring speed is 100r/ min, the leaching time is 8h;
  • Step 5 perform suction filtration while hot, separate solid and liquid, and obtain filtrate
  • Step 6 Place the filtrate in the reaction kettle, add nanometer calcium carbonate with a particle size of 1-100nm and 3g/L sodium dodecylbenzene sulfonate according to a solid-liquid ratio of 15g/L, and add ethylenediaminetetraacetic acid. 4.2 times the molar amount of tetrasodium sulfuric acid, seal it, control the temperature in the kettle to 120°C, and the reaction time to 6 hours;
  • Step 7 After the reaction is completed, the reaction kettle is cooled to room temperature. The materials in the kettle are divided into three layers, and solid-liquid separation is performed. The obtained filtrate is sodium sulfate solution, and the upper layer is a mixture of foam and solid. After solid-liquid separation, the solid obtained is ethyl alcohol. Diamine tetraacetic acid, add 4 times the molar amount of sodium hydroxide to prepare tetrasodium ethylenediamine tetraacetate, and reuse it in step 4. The obtained bottom solid is washed with deionized water and dried at 100°C for 2 hours to obtain sulfuric acid. Calcium whiskers.
  • a method for preparing calcium sulfate whiskers by purifying and purifying phosphogypsum The difference from Example 1 is that in step 4, tetrasodium ethylenediaminetetraacetate is replaced by ammonium acetate.
  • the specific process is:
  • Step 1 Mix phosphogypsum and primary water at a mass ratio of 1:2, then add sodium hydroxide to adjust the slurry, and control the pH of the slurry to 8;
  • Step 2 solid-liquid separation, the obtained filtrate enters the wastewater treatment system, and the obtained filter cake is placed in a pulse airflow dryer for drying.
  • the inlet air temperature is controlled to 450°C, the outlet air temperature is 180°C, and the air inlet speed is 20m/s.
  • the residence time is 5s;
  • Step 3 Place the dried material in a calcining furnace for calcination, blow in high-temperature hot air, control the inlet air temperature to 800°C, the outlet air temperature to 450°C, the air inlet speed to 20m/s, and the residence time to 5s;
  • Step 4 Add the calcined phosphogypsum to an aqueous solution of 1.0 mol/L ammonium acetate according to a solid-to-liquid ratio of 170g/L for leaching.
  • the reaction temperature is controlled to 95°C
  • the stirring speed is 300r/min
  • the leaching time is 4h;
  • Step 5 perform suction filtration while hot, separate solid and liquid, and obtain filtrate
  • Step 6 Place the filtrate in the reaction kettle, add 4.5 times the molar amount of ammonium acetate and sulfuric acid, seal it, control the temperature in the kettle to 150°C, and the reaction time to 3 hours;
  • Step 7 After the reaction is completed, the reaction kettle is cooled to room temperature. The materials in the kettle are divided into two layers, and the solid and liquid are separated. The obtained filtrate is a mixed solution of ammonium sulfate and acetic acid. The obtained bottom solid is washed with deionized water and washed at 120 Dry at °C for 1 hour to obtain calcium sulfate whiskers.
  • a method for preparing calcium sulfate whiskers by purifying and purifying phosphogypsum The difference from Example 1 is that nanometer calcium carbonate and surfactant are not used.
  • the specific process is:
  • Step 1 Mix phosphogypsum and primary water at a mass ratio of 1:2, then add sodium hydroxide to adjust the slurry, and control the pH of the slurry to 8;
  • Step 2 solid-liquid separation, the obtained filtrate enters the wastewater treatment system, and the obtained filter cake is placed in a pulse airflow dryer for drying.
  • the inlet air temperature is controlled to 450°C, the outlet air temperature is 180°C, and the air inlet speed is 20m/s.
  • the residence time is 5s;
  • Step 3 Place the dried material in a calcining furnace for calcination, blow in high-temperature hot air, control the inlet air temperature to 800°C, the outlet air temperature to 450°C, the air inlet speed to 20m/s, and the residence time to 5s;
  • Step 4 Add the calcined phosphogypsum to an aqueous solution of tetrasodium ethylenediaminetetraacetate of 1.0 mol/L according to a solid-to-liquid ratio of 170g/L for leaching.
  • the reaction temperature is controlled to 95°C and the stirring speed is 300r/ min, the leaching time is 4h;
  • Step 5 perform suction filtration while hot, separate solid and liquid, and obtain filtrate
  • Step 6 Place the filtrate in the reaction kettle, add 4.5 times the molar amount of sulfuric acid of tetrasodium ethylenediaminetetraacetate, seal, control the temperature in the kettle to 150°C, and the reaction time to 3 hours;
  • Step 7 After the reaction is completed, the reaction kettle is cooled to room temperature. After standing, the materials in the kettle are suspended and the solid and liquid are separated. The obtained filtrate is a sodium sulfate solution, and the solid obtained is a mixture of ethylenediaminetetraacetic acid and calcium sulfate whiskers. Mixture, add 4 times the molar amount of sodium hydroxide to the solid to dissolve it to form tetrasodium ethylenediaminetetraacetate, which can be reused in step 4. The remaining bottom solid is washed with deionized water and dried at 120°C for 1 hour to obtain sulfuric acid. Calcium whiskers.
  • the leaching agent of Comparative Example 1 is ammonium acetate, which utilizes the salt effect to increase the solubility of calcium sulfate.
  • the yield of Comparative Example 1 is still much lower than that of the Example, and the leaching agent cannot be reused, and the reagent consumption is More.
  • the purity of the calcium sulfate whiskers obtained in Comparative Example 2 is low, and the residual ethylenediaminetetraacetic acid cannot be completely removed.
  • soaking in alkali solution will not only introduce sodium ions, but the newly generated tetrasodium ethylenediaminetetraacetate will also cause the formation of calcium sulfate.
  • whiskers dissolve, resulting in a reduction in yield; this shows that the present invention utilizes the joint action of carbon dioxide produced by nano-calcium carbonate and surfactants to achieve efficient separation of products, and can obtain high purity and high yield through simple operations.
  • Calcium sulfate whiskers are used to achieve efficient separation of products, and can obtain high purity and high yield through simple operations.

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Abstract

一种磷石膏净化提纯制备硫酸钙晶须的方法，将磷石膏制浆，调节浆料pH，固液分离，滤渣煅烧，所得煅烧料加入到含乙二胺四乙酸盐的水溶液中加热浸出，固液分离，将滤液、纳米碳酸钙、表面活性剂和硫酸混合进行水热反应，降温后分层，即得硫酸钙晶须。利用诱导晶种纳米碳酸钙产生二氧化碳，在表面活性剂的作用下，负载新生成且密度较低的乙二胺四乙酸上浮，实现硫酸钙、EDTA、硫酸盐溶液三者的高效分离。

Description

磷石膏净化提纯制备硫酸钙晶须的方法 技术领域
本发明属于磷化工中磷石膏处理技术领域，具体涉及一种磷石膏净化提纯制备硫酸钙晶须的方法。
背景技术
磷石膏是磷化工企业采用湿法工艺生产磷酸排出的固体废渣，主要成分为二水硫酸钙，此外还含有未分解完的磷矿、有机质、二氧化硅、氟化物、磷酸根、硫酸、少量的金属(钾、钠、铁、铝)和重金属等杂质。通常情况下，采用湿法工艺生产1t磷酸会产生4.5～5.5t磷石膏。绝大部分的磷石膏以建库堆存的方式进行处置，不但占用大量土地，同时由于磷石膏中的有害物质的渗漏转移更给周围环境带来了严重环境问题。磷石膏中含有丰富的钙、硫，又是宝贵的资源，改性后的磷石膏可用来替代日益紧张的天然石膏资源。因此，从环境保护和资源利用的角度，磷石膏废渣的处理与利用已迫在眉睫。
现有技术中，申请号为200410021766.4的中国专利公开了用磷石膏生产建筑装饰材料和墙体材料的方法，申请号为200410081601.6的中国专利公开了用磷石膏生产的型材及其制法，申请号为200410060727.5的中国专利公开了石灰在磷石膏无害化处理上的应用，申请号为200910272772.X的中国专利公开了将石灰与磷石膏按照质量比(0.5-1.5)：100混合后，使得磷石膏中的有害成分转化，申请号为201110188922.6的中国专利公开了将磷石膏进行清洗、中和、脱水、煅烧、包装等步骤实现无害化处理；这些处理磷石膏的技术方案，投资高，实施比较困难，所得产品也仅能用于建筑材料。
硫酸钙晶须是无水硫酸钙的纤维状单晶体，又称石膏晶须，是一种针状白色纤维。硫酸钙晶须具有高强度、抗化学腐蚀、耐高温、韧性好、和橡胶等聚合物的亲和力强等优点，可广泛应用于橡胶、塑料、摩擦材料、涂料、油漆、造纸、催化、导电粉等新型材料领域。但目前世界各国的生产方法不仅生产成本高、程序复杂，而且污染重，因此，利用工业废渣磷石膏制备石膏晶须，研究石膏晶须的廉价且简易的制备方法不仅环境友 好，同时具有极好的社会经济效益。
发明内容
本发明旨在至少解决上述现有技术中存在的技术问题之一。为此，本发明提出一种磷石膏净化提纯制备硫酸钙晶须的方法。
根据本发明的一个方面，提出了一种磷石膏净化提纯制备硫酸钙晶须的方法，包括以下步骤：
S1：将磷石膏与水混合制浆，并加碱调节浆料pH，固液分离得到滤渣；
S2：所述滤渣经干燥和煅烧，得到煅烧料；
S3：将所述煅烧料加入到含乙二胺四乙酸盐的水溶液中，加热浸出，再固液分离，得到滤液；
S4：将所述滤液、纳米碳酸钙、表面活性剂和硫酸混合，进行水热反应；
S5：步骤S4所述水热反应后的物料经降温后分层，取底层固体即得所述硫酸钙晶须。
在本发明的一些实施方式中，步骤S1中，所述磷石膏与水的质量比为1：(1-2)。
在本发明的一些实施方式中，步骤S1中，所述碱为氢氧化钠或氨水中的至少一种。
在本发明的一些实施方式中，步骤S1中，所述浆料pH调节至7-8。
在本发明的一些实施方式中，步骤S2中，所述干燥采用气流干燥，控制进气温度为400-450℃，出气温度为150-180℃，进气速度为15-20m/s，停留时间为5-10s。
在本发明的一些实施方式中，步骤S2中，所述煅烧的过程为：鼓入热风，控制进气温度为600-800℃，出气温度为400-450℃，进气速度为15-20m/s，停留时间为5-10s。
在本发明的一些实施方式中，步骤S3中，所述水溶液中乙二胺四乙酸盐的浓度为0.5-1.0mol/L，所述煅烧料与水溶液的固液比为100-180g/L。
在本发明的一些实施方式中，步骤S3中，所述乙二胺四乙酸盐选自乙二胺四乙酸四钠。
在本发明的一些实施方式中，步骤S3中，所述加热浸出的温度为80-95℃。
在本发明的一些实施方式中，步骤S3中，所述加热浸出在转速为100-300r/min的搅拌下进行。
在本发明的一些实施方式中，步骤S3中，所述加热浸出的时间为4-8h。
在本发明的一些实施方式中，步骤S4中，所述纳米碳酸钙的加入量为15-30g/L滤液。
在本发明的一些实施方式中，步骤S4中，所述纳米碳酸钙的粒径为1-100nm。
在本发明的一些实施方式中，步骤S4中，所述表面活性剂的加入量为3-8g/L滤液。
在本发明的一些实施方式中，步骤S4中，所述表面活性剂为硫酸酯盐和/或磺酸盐。进一步地，所述硫酸酯盐选自脂肪醇硫酸盐、仲烷基硫酸盐、脂肪醇聚氧乙烯醚硫酸酯盐或脂肪酸衍生物的硫酸酯盐中的至少一种；所述磺酸盐选自烷基苯磺酸盐、烷基萘磺酸盐、烷基磺酸盐、石油磺酸盐或木质素磺酸盐中的至少一种。
在本发明的一些实施方式中，步骤S4中，所述硫酸的加入量为乙二胺四乙酸盐摩尔量的4.2-4.5倍。
在本发明的一些实施方。式中，步骤S4中，所述水热反应的温度为120-150℃。进一步地，所述水热反应的时间为3-6h。
在本发明的一些实施方式中，步骤S4中，所述降温后的温度为20-40℃。优选的，所述降温后的温度为20-28℃。
在本发明的一些实施方式中，步骤S5中，所述分层共分为三层，上层为泡沫与乙二胺四乙酸固体的混合物，将上层的混合物固液分离得到乙二胺四乙酸，再将乙二胺四乙酸与碱混合配制成乙二胺四乙酸盐，回用于步骤S3中。进一步地，所述碱选自氢氧化钠。
在本发明的一些实施方式中，步骤S5中，还包括：将所述底层固体用水洗涤，在100-120℃下干燥1-2h，得所述硫酸钙晶须。
根据本发明的一种优选的实施方式，至少具有以下有益效果：
1、本发明首先通过碱液调浆中和磷石膏中的酸性物质，然后经干燥、煅烧脱水， 同时使其中的金属杂质以难溶的氧化物形式存在，避免后续浸出过程引入杂质金属。部分反应如下：
Fe 3++3OH -→Fe(OH) 3；
Al 3++3OH -→Al(OH) 3；
2Fe(OH) 3→Fe 2O 3+3H 2O；
2Al(OH) 3→Al 2O 3+3H 2O。
2、利用钙离子与EDTA的螯合作用，采用乙二胺四乙酸盐与磷石膏中的硫酸钙反应，生成可溶性的螯合钙，再与硫酸进行水热反应，使硫酸钙进行重结晶，并生成乙二胺四乙酸和硫酸盐。反应原理如下(以乙二胺四乙酸四钠为例)：
CaSO 4·2H 2O+Na 4EDTA→CaNa 2EDTA+Na 2SO 4+2H 2O；
CaNa 2EDTA+2H 2SO 4+2H 2O→Na 2SO 4+CaSO 4·2H 2O+EDTA。
3、在水热过程中，利用纳米碳酸钙作为诱导晶种，在硫酸的作用下，不断生成硫酸钙晶须的同时，诱导晶种纳米碳酸钙不断溶解，并产生二氧化碳，在表面活性剂的作用下，使二氧化碳形成气泡，并负载新生成且密度较低的乙二胺四乙酸上浮，较重的硫酸钙则沉在底部，中层为硫酸盐溶液，由此实现硫酸钙、EDTA、硫酸盐溶液三者的分离，从而得到较为纯净的硫酸钙晶须，其纯度达到99％以上。
4、作为优选的，反应最后产生的EDTA经与碱反应，重新作为浸出剂进行磷石膏的浸出，避免了EDTA的消耗。
5、本发明通过对磷石膏进行浸出并重新结晶的方式，获得价值较高的硫酸钙晶须，使固废磷石膏得到了进一步的开发和利用，实现了环境的保护，提高了价值。
附图说明
下面结合附图和实施例对本发明做进一步的说明，其中：
图1为本发明实施例1的工艺流程图；
图2为本发明实施例1制备的硫酸钙晶须SEM图。
具体实施方式
以下将结合实施例对本发明的构思及产生的技术效果进行清楚、完整地描述，以充分地理解本发明的目的、特征和效果。显然，所描述的实施例只是本发明的一部分实施例，而不是全部实施例，基于本发明的实施例，本领域的技术人员在不付出创造性劳动的前提下所获得的其他实施例，均属于本发明保护的范围。
实施例1
一种磷石膏净化提纯制备硫酸钙晶须的方法，参照图1，具体过程为：
步骤1，将磷石膏与一次水按照质量比1：2混合后，加入氢氧化钠进行调浆，控制浆料pH为8；
步骤2，固液分离，所得滤液进入废水处理系统，所得滤饼置于脉冲气流式干燥机中进行干燥，控制进气温度为450℃，出气温度为180℃，进气速度为20m/s，停留时间为5s；
步骤3，将干燥后的物料置于煅烧炉内煅烧，鼓入高温热风，控制进气温度为800℃，出气温度为450℃，进气速度为20m/s，停留时间为5s；
步骤4，按照固液比170g/L将煅烧后的磷石膏加入到1.0mol/L的乙二胺四乙酸四钠的水溶液中进行浸出，浸出过程控制反应温度为95℃，搅拌转速为300r/min，浸出时间为4h；
步骤5，趁热抽滤，固液分离，得到滤液；
步骤6，将滤液置于反应釜内，按照固液比30g/L加入粒径为1-100nm的纳米碳酸钙以及8g/L的十二烷基硫酸钠，并加入乙二胺四乙酸四钠4.5倍摩尔量的硫酸，密封，控制釜内温度为150℃，反应时间为3h；
步骤7，反应结束后，将反应釜冷却至室温，釜内物料分为三层，固液分离，得到的滤液为硫酸钠溶液，得到上层为泡沫和固体混合物，经固液分离得到固体为乙二胺四乙酸，加入4倍摩尔量的氢氧化钠配制成乙二胺四乙酸四钠，重新用于步骤4中，得到的底层固体经去离子水洗涤后在120℃下干燥1h即得硫酸钙晶须，其形貌如图2所见。
实施例2
一种磷石膏净化提纯制备硫酸钙晶须的方法，具体过程为：
步骤1，将磷石膏与一次水按照质量比1：1.5混合后，并加入氨水进行调浆，控制浆料pH为7.5；
步骤2，固液分离，所得滤液进入废水处理系统，所得滤饼置于脉冲气流式干燥机中进行干燥，控制进气温度为430℃，出气温度为165℃，进气速度为18m/s，停留时间为8s；
步骤3，将干燥后的物料置于煅烧炉内煅烧，鼓入高温热风，控制进气温度为600℃，出气温度为430℃，进气速度为18m/s，停留时间为8s；
步骤4，按照固液比80g/L将煅烧后的磷石膏加入到0.5mol/L的乙二胺四乙酸四钠的水溶液中进行浸出，浸出过程控制反应温度为90℃，搅拌转速为200r/min，浸出时间为6h；
步骤5，趁热抽滤，固液分离，得到滤液；
步骤6，将滤液置于反应釜内，按照固液比20g/L加入粒径为1-100nm的纳米碳酸钙以及5g/L的十六烷基磺酸钠，并加入乙二胺四乙酸四钠4.3倍摩尔量的硫酸，密封，控制釜内温度为135℃，反应时间为5h；
步骤7，反应结束后，将反应釜冷却至室温，釜内物料分为三层，固液分离，得到的滤液为硫酸钠溶液，得到上层为泡沫和固体混合物，经固液分离得到固体为乙二胺四乙酸，加入4倍摩尔量的氢氧化钠配制成乙二胺四乙酸四钠，重新用于步骤4中，得到的底层固体经去离子水洗涤后在110℃下干燥1.5h即得硫酸钙晶须。
实施例3
一种磷石膏净化提纯制备硫酸钙晶须的方法，具体过程为：
步骤1，将磷石膏与一次水按照质量比1：1混合后，并加入氨水进行调浆，控制浆料pH为7；
步骤2，固液分离，所得滤液进入废水处理系统，所得滤饼置于脉冲气流式干燥机中进行干燥，控制进气温度为400℃，出气温度为150℃，进气速度为15m/s，停留时间 为10s；
步骤3，将干燥后的物料置于煅烧炉内煅烧，鼓入高温热风，控制进气温度为600℃，出气温度为400℃，进气速度为15m/s，停留时间为10s；
步骤4，按照固液比17g/L将煅烧后的磷石膏加入到0.1mol/L的乙二胺四乙酸四钠的水溶液中进行浸出，浸出过程控制反应温度为80℃，搅拌转速为100r/min，浸出时间为8h；
步骤5，趁热抽滤，固液分离，得到滤液；
步骤6，将滤液置于反应釜内，按照固液比15g/L加入粒径为1-100nm的纳米碳酸钙以及3g/L的十二烷基苯磺酸钠，并加入乙二胺四乙酸四钠4.2倍摩尔量的硫酸，密封，控制釜内温度为120℃，反应时间为6h；
步骤7，反应结束后，将反应釜冷却至室温，釜内物料分为三层，固液分离，得到的滤液为硫酸钠溶液，得到上层为泡沫和固体混合物，经固液分离得到固体为乙二胺四乙酸，加入4倍摩尔量的氢氧化钠配制成乙二胺四乙酸四钠，重新用于步骤4中，得到的底层固体经去离子水洗涤后在100℃下干燥2h即得硫酸钙晶须。
对比例1
一种磷石膏净化提纯制备硫酸钙晶须的方法，与实施例1的区别在于，步骤4乙二胺四乙酸四钠替换成醋酸铵，具体过程为：
步骤1，将磷石膏与一次水按照质量比1：2混合后，并加入氢氧化钠进行调浆，控制浆料pH为8；
步骤2，固液分离，所得滤液进入废水处理系统，所得滤饼置于脉冲气流式干燥机中进行干燥，控制进气温度为450℃，出气温度为180℃，进气速度为20m/s，停留时间为5s；
步骤3，将干燥后的物料置于煅烧炉内煅烧，鼓入高温热风，控制进气温度为800℃，出气温度为450℃，进气速度为20m/s，停留时间为5s；
步骤4，按照固液比170g/L将煅烧后的磷石膏加入到1.0mol/L的醋酸铵的水溶液 中进行浸出，浸出过程控制反应温度为95℃，搅拌转速为300r/min，浸出时间为4h；
步骤5，趁热抽滤，固液分离，得到滤液；
步骤6，将滤液置于反应釜内，加入醋酸铵4.5倍摩尔量的硫酸，密封，控制釜内温度为150℃，反应时间为3h；
步骤7，反应结束后，将反应釜冷却至室温，釜内物料分为两层，固液分离，得到的滤液为硫酸铵和醋酸的混合溶液，得到的底层固体经去离子水洗涤后在120℃下干燥1h即得硫酸钙晶须。
对比例2
一种磷石膏净化提纯制备硫酸钙晶须的方法，与实施例1的区别在于，不使用纳米碳酸钙和表面活性剂，具体过程为：
步骤1，将磷石膏与一次水按照质量比1：2混合后，加入氢氧化钠进行调浆，控制浆料pH为8；
步骤2，固液分离，所得滤液进入废水处理系统，所得滤饼置于脉冲气流式干燥机中进行干燥，控制进气温度为450℃，出气温度为180℃，进气速度为20m/s，停留时间为5s；
步骤3，将干燥后的物料置于煅烧炉内煅烧，鼓入高温热风，控制进气温度为800℃，出气温度为450℃，进气速度为20m/s，停留时间为5s；
步骤4，按照固液比170g/L将煅烧后的磷石膏加入到1.0mol/L的乙二胺四乙酸四钠的水溶液中进行浸出，浸出过程控制反应温度为95℃，搅拌转速为300r/min，浸出时间为4h；
步骤5，趁热抽滤，固液分离，得到滤液；
步骤6，将滤液置于反应釜内，加入乙二胺四乙酸四钠4.5倍摩尔量的硫酸，密封，控制釜内温度为150℃，反应时间为3h；
步骤7，反应结束后，将反应釜冷却至室温，静置后，釜内物料悬浊，固液分离，得到的滤液为硫酸钠溶液，得到固体为乙二胺四乙酸与硫酸钙晶须的混合物，向固体中 加入4倍摩尔量的氢氧化钠溶解生成乙二胺四乙酸四钠，重新用于步骤4中，残留的底层固体经去离子水洗涤后在120℃下干燥1h即得硫酸钙晶须。
表1实施例及对比例所得硫酸钙晶须的纯度及收率
  纯度 收率
实施例1 99.27％ 95.76％
实施例2 99.36％ 94.37％
实施例3 99.39％ 93.22％
对比例1 98.79％ 81.73％
对比例2 97.31％ 88.61％
由表1可见，对比例1的浸出剂为醋酸铵，利用了盐效应提高硫酸钙的溶解度，但对比例1的收率仍然比实施例低得多，而且浸出剂无法重复利用，试剂耗量较多。对比例2所得硫酸钙晶须纯度较低，无法完全去除残留的乙二胺四乙酸，且采用碱液浸泡，不仅会引入钠离子，新生成的乙二胺四乙酸四钠还会造成硫酸钙晶须少量溶出，导致收率降低；由此表明，本发明利用纳米碳酸钙产生的二氧化碳与表面活性剂的共同作用实现产物的高效分离，通过简单的操作即可获得高纯度和高收率的硫酸钙晶须。
上面结合附图对本发明实施例作了详细说明，但是本发明不限于上述实施例，在所属技术领域普通技术人员所具备的知识范围内，还可以在不脱离本发明宗旨的前提下作出各种变化。此外，在不冲突的情况下，本发明的实施例及实施例中的特征可以相互组合。

Claims (10)

  1. 一种磷石膏净化提纯制备硫酸钙晶须的方法，其特征在于，包括以下步骤：
    S1：将磷石膏与水混合制浆，并加碱调节浆料pH，固液分离得到滤渣；
    S2：所述滤渣经干燥和煅烧，得到煅烧料；
    S3：将所述煅烧料加入到含乙二胺四乙酸盐的水溶液中，加热浸出，再固液分离，得到滤液；
    S4：将所述滤液、纳米碳酸钙、表面活性剂和硫酸混合，进行水热反应；
    S5：步骤S4所述水热反应后的物料经降温后分层，取底层固体即得所述硫酸钙晶须。
  2. 根据权利要求1所述的方法，其特征在于，步骤S1中，所述浆料pH调节至7-8。
  3. 根据权利要求1所述的方法，其特征在于，步骤S2中，所述干燥采用气流干燥，控制进气温度为400-450℃，出气温度为150-180℃，进气速度为15-20m/s，停留时间为5-10s。
  4. 根据权利要求1所述的方法，其特征在于，步骤S2中，所述煅烧的过程为：鼓入热风，控制进气温度为600-800℃，出气温度为400-450℃，进气速度为15-20m/s，停留时间为5-10s。
  5. 根据权利要求1所述的方法，其特征在于，步骤S3中，所述水溶液中乙二胺四乙酸盐的浓度为0.5-1.0mol/L，所述煅烧料与水溶液的固液比为100-180g/L。
  6. 根据权利要求1所述的方法，其特征在于，步骤S3中，所述加热浸出的温度为80-95℃。
  7. 根据权利要求1所述的方法，其特征在于，步骤S4中，所述纳米碳酸钙的加入量为15-30g/L滤液。
  8. 根据权利要求1所述的方法，其特征在于，步骤S4中，所述表面活性剂的加入量为3-8g/L滤液。
  9. 根据权利要求1所述的方法，其特征在于，步骤S4中，所述水热反应的温度为 120-150℃。
  10. 根据权利要求1所述的方法，其特征在于，步骤S5中，所述分层共分为三层，上层为泡沫与乙二胺四乙酸固体的混合物，将上层的混合物固液分离得到乙二胺四乙酸，再将乙二胺四乙酸与碱混合配制成乙二胺四乙酸盐，回用于步骤S3中。
    ，
PCT/CN2022/117484 2022-07-28 2022-09-07 磷石膏净化提纯制备硫酸钙晶须的方法 WO2024021234A1 (zh)

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