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WO2023202270A1 - 一种分级利用磷矿石中氟、硅资源的方法 - Google Patents

一种分级利用磷矿石中氟、硅资源的方法 Download PDF

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Publication number
WO2023202270A1
WO2023202270A1 PCT/CN2023/081412 CN2023081412W WO2023202270A1 WO 2023202270 A1 WO2023202270 A1 WO 2023202270A1 CN 2023081412 W CN2023081412 W CN 2023081412W WO 2023202270 A1 WO2023202270 A1 WO 2023202270A1
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Prior art keywords
fluorine
solution
extraction
gas
desorption
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English (en)
French (fr)
Inventor
权晓威
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Chtem Ltd
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Chtem Ltd
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Priority to US18/296,356 priority Critical patent/US11891344B2/en
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    • C—CHEMISTRY; METALLURGY
    • C05—FERTILISERS; MANUFACTURE THEREOF
    • C05B—PHOSPHATIC FERTILISERS
    • C05B17/00—Other phosphatic fertilisers, e.g. soft rock phosphates, bone meal
    • 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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/08—Compounds containing halogen
    • C01B33/10—Compounds containing silicon, fluorine, and other elements
    • C01B33/103—Fluosilicic acid; Salts thereof
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/08—Compounds containing halogen
    • C01B33/107—Halogenated silanes
    • C01B33/10705—Tetrafluoride
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/18—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B7/00—Halogens; Halogen acids
    • C01B7/19—Fluorine; Hydrogen fluoride
    • C01B7/191—Hydrogen fluoride
    • C01B7/193—Preparation from silicon tetrafluoride, fluosilicic acid or fluosilicates

Definitions

  • the present invention relates to the technical field of separation and purification of fluorine and silicon compounds. Specifically, it relates to a method using phosphate rock as raw material to recover and purify fluorine and silicon compounds in the process of producing phosphoric acid and phosphate fertilizer and utilizing the fluorine and silicon compounds in the phosphate rock. silicon resources approach.
  • a large amount of fluorine and silicon-containing gases will be produced during the wet process, and direct discharge will seriously pollute the environment.
  • Most phosphate fertilizer companies can only absorb gases containing fluorine and silicon with water to generate fluorosilicic acid, and only convert waste gas into wastewater.
  • the domestic production of wet phosphoric acid is more than 10 million tons per year, and the by-product fluosilicic acid is about 3.75 million tons based on 15% content.
  • Fluorosilicic acid is an important intermediate product in the process of recovering fluorine and silicon resources in phosphate rock. The higher its concentration, the more conducive it is to subsequent processing. So far, many phosphate fertilizer companies have been practicing in this field for a long time. They usually absorb it through pipeline spraying. The final concentration of fluorosilicic acid obtained is about 18% by mass. It is necessary to maintain a high fluorine recovery rate and a high fluorosilicic acid concentration. The technical difficulty of acid solution concentration is relatively high. Among them, the process of preparing anhydrous hydrogen fluoride from fluorosilicic acid is relatively mature, but the silica obtained in this preparation process often contains 10% to 20% fluorine element, so the application of this silica is greatly limited. Currently, there is basically no way to reduce the fluorine element entrained in the silica generation process when exploring the defluorination and purification process of fluorine-containing silica.
  • silica is generally produced during the hydration process of silicon tetrafluoride.
  • the entrained fluorine includes two types: 1. Free fluorine, accounting for about 70%, mainly sticky fluorine. Fluorosilicic acid attached to the surface of silica can be removed by rinsing. 2. Lattice fluorine, accounting for about 30%, is due to the fact that when silicon tetrafluoride bubbles come into contact with water, the Si-F functional groups inside the bubbles are absorbed by the Si-O bond network generated by the gas-liquid interface reaction before they can react with water. Caused by siege.
  • the present invention aims to provide a production process for efficiently and economically extracting fluorine and silicon elements from phosphate rock and obtaining high-purity products. This production process is also suitable for processing other phosphates containing fluorine and silicon.
  • a method for graded utilization of fluorine and silicon resources in phosphate rock which is characterized by including the following steps.
  • Step (1) Acidification: Mix and react sulfuric acid or phosphoric acid with phosphate rock to generate dilute phosphoric acid or/and phosphate fertilizer, and at the same time produce tail gas containing fluorine and silicon.
  • the main components of the tail gas are water vapor and gaseous fluosilicic acid.
  • Step (2) absorption: absorb the tail gas and fluorine-containing secondary steam with water to obtain an acidic solution containing fluorine and silicon.
  • the absorption may be external cooling forced circulation three-stage countercurrent vacuum absorption.
  • the unabsorbed tail gas is sent to deep absorption;
  • the absorbent used in deep absorption is Na 2 CO 3 , NaHCO 3 or KOH solution, and the set temperature is no higher than 40°C.
  • the reaction generates corresponding precipitated salts to achieve deep absorption. Satisfy environmental protection.
  • Step (3) osmotic concentration: use a phosphate solution or a phosphoric acid solution to perform a forward osmosis operation with the acidic solution.
  • the phosphate solution or the phosphoric acid solution absorbs part of the solvent in the acidic solution to obtain a dilute acid solution or a dilute salt solution.
  • the obtained dilute acid solution is sent to step (1) to be mixed with phosphate rock; the concentration of the acidic solution increases to obtain a concentrated solution.
  • This invention innovatively adopts forward osmosis operation to concentrate fluosilicic acid to a mass fraction of 45-60% fluosilicic acid, providing huge flexibility for subsequent operations. .
  • Using phosphate solution or phosphoric acid solution as the driving fluid facilitates the regeneration and circulation of the driving fluid in the phosphoric acid and phosphate fertilizer production lines.
  • Step (4), concentration and filtration Pass the concentrated solution and silicon fluoride gas into the microemulsion reactor to perform a concentration operation to continue to increase the concentration of the concentrated solution; then filter and separate to obtain SiO 2 solid, containing Fluorine solution and waste gas, the waste gas is sent to step (2) to be absorbed together with the tail gas.
  • the present invention creatively mixes the concentrated solution with surfactant thoroughly first, and then mixes it with SiF 4 gas; this is because the hydration process of silicon tetrafluoride can easily produce crystals.
  • Lattice fluorine because the lattice fluorine is surrounded and protected by a strong Si-O bond network, once the lattice fluorine is formed, it cannot be removed by physical washing. The surrounding Si-O bonds must be loosened through chemical methods to achieve the entry and exit of substances, thereby providing Separation creates conditions.
  • the existing technology only finds ways to remove lattice fluorine after it is generated, which is extremely difficult.
  • the present invention creatively focuses on the nature of the reaction between silicon tetrafluoride and water, and seeks a solution before the formation of lattice fluorine. That is, the concentrated solution is fully mixed with the surfactant first, and the surfactant is used to reduce the surface tension, so that the contact area of the two-phase surfaces is larger, tending to spread, and suppressing the situation that the bubbles are not in contact with the liquid, and then with the SiF 4 gases are mixed to improve the contact between the gas and liquid phases, thereby inhibiting the formation of lattice fluorine in silica (white carbon black), and thereby obtaining high-purity silica.
  • the volume ratio of the surfactant to the concentrated solution is 1:200 to 1:50.
  • Step (5) extraction: add the extraction phase to the fluorine-containing solution, mix thoroughly for extraction, and separate the phases to obtain the load phase and the raffinate.
  • the extraction phase consists of an extraction agent and a diluent, the volume fraction of the extraction agent is not greater than 80%, and the diluent is one or more of kerosene, isopropyl ether, and C 6 to C 14 hydrocarbons. mixture.
  • the extraction operation includes cation extraction and anion extraction, and the loaded phase after cation extraction and anion extraction is washed, regenerated and then recycled.
  • the surfactant in the above step (4) can also be directly used as the extraction phase of cationic extraction.
  • the volume ratio of the extraction phase of the cation extraction to the fluorine-containing solution is 0.5:1 to 6:1
  • the extraction agent of the extraction phase of the cation extraction is organic phosphines, phospholipids, carboxylic acids, and sulfonic acids.
  • the volume ratio of the extraction phase of the anion extraction to the fluorine-containing solution is 0.5:1 to 6:1
  • the extraction agent of the extraction phase of the anion extraction is an organic amine extraction agent.
  • the loaded phase extracted by the cationic extraction phase is washed with water and regenerated with 5% to 40% dilute sulfuric acid for recycling.
  • the volume ratio of the loaded phase after extraction by the cationic extraction phase to water is 10:1 to 40:1
  • the volume ratio of the loaded phase after washing to 5% to 40% dilute sulfuric acid is 10:1 to 40:1.
  • the loaded phase after extraction by the anionic extraction phase is washed with water and 2% to 25% ammonia water is regenerated and recycled.
  • the volume ratio of the load phase after extraction by the anion extraction phase to water is 10:1 to 40:1
  • the volume ratio of the load phase after washing to 2% to 25% ammonia water is 10:1 to 40:1.
  • the residual liquid produced after two water washings is returned to step (2) for absorbing tail gas; the regeneration waste liquid produced after two regenerations is used for phosphate rock acidification or fertilizer production.
  • Step (6) liquid adsorption: adsorption to remove impurities in the raffinate to obtain a refined solution; the adsorption includes activated carbon adsorption, cation adsorption and anion adsorption.
  • the activated carbon, cation adsorbent and anion adsorbent are desorbed after being saturated. Attached regeneration can be reused.
  • the desorption liquid is returned to the step (2) to adsorb the tail gas; the desorption liquid formed by desorption of sodium hydroxide solution and ammonia water is used for fertilizer production, and the desorption liquid formed by desorption of sulfuric acid solution is used for Phosphate rock acidification.
  • Step (7) dehydration: fully mix the purified solution and the dehydrating agent in the microemulsion reactor, fully contact through two-stage countercurrent, absorb the moisture in the purified solution, promote the decomposition of fluorosilicic acid, and obtain crude SiF 4 gas and HF-sulfuric acid solution, the HF-sulfuric acid solution is separated by steam stripping and distillation to produce high-purity anhydrous hydrogen fluoride with a purity of not less than 99% and by-product waste sulfuric acid, and the waste sulfuric acid is sent to step (1) to be mixed with phosphorus Mineral mix.
  • the dehydrating agent is one or a mixture of sulfur trioxide, fuming sulfuric acid, and concentrated sulfuric acid with a mass fraction greater than 93%.
  • the purpose of using a microemulsion reactor to complete the dehydration process is to enhance the uniformity of material mixing and suppress the production of fluorosilicone.
  • Step (8) impurity removal: adsorb the impurities in the crude SiF 4 gas through gaseous adsorption to obtain impurity removal gas.
  • gaseous adsorption includes activated carbon adsorption, molecular sieve adsorption and modified adsorbent adsorption, and the activated carbon, molecular sieve and modified adsorbent can be reused after desorption and regeneration after being saturated.
  • the modified adsorbent is porous alumina surface-modified by an organic amine, silica surface-modified by an organic amine, or porous polymer surface-modified by an organic amine.
  • the activated carbon and molecular sieve are desorbed and regenerated using absolute dry nitrogen. They are first desorbed at a temperature of 100-150°C and a pressure of 0.2-0.3MPaA, and the desorbed gas is sent to the step (4) for use The concentrated solution is concentrated; then desorbed at a temperature of 200 to 250°C and a pressure of 0.3 to 0.5MPaA, and the desorbed gas is sent to fertilizer production. The activated carbon and molecular sieve are desorbed and regenerated using a mixture of absolutely dry nitrogen and ammonia-nitrogen with a volume fraction of 2% to 10%.
  • the desorbent of the modified adsorbent is a mixture of absolute dry nitrogen and ammonia-containing nitrogen with a volume fraction of 2% to 10%.
  • the desorption temperature is greater than 100°C, and the desorption pressure is not greater than 80KPaA.
  • the desorption gas formed by absolutely dry nitrogen is sent to the concentration and filtration step of the fluorosilicic acid solution; the desorption gas formed by the mixed gas containing ammonia nitrogen is sent to the tail washing section of fertilizer production.
  • Step (9) low-temperature distillation: perform low-temperature rectification on the impurity removal gas to deeply remove low-boiling point and high-boiling point impurities to obtain impurity gas and high-purity SiF 4 with a purity of not less than 99%.
  • the impurity gas is passed into the concentrated solution in step (4) as SiF 4 gas.
  • the low-temperature distillation includes one-stage distillation and two-stage distillation; the first-stage distillation first removes low-boiling point impurities, the tower top pressure is 0.95 ⁇ 1.15MPaA, and the temperature is -56°C ⁇ -51°C.
  • the pressure of the kettle is 1.0 ⁇ 1.2MPaA, and the temperature is -51°C ⁇ -47°C; the two-stage distillation removes high boiling point impurities, the pressure at the top of the tower is 0.85 ⁇ 1.05MPaA, and the temperature is -60°C ⁇ -55°C.
  • the pressure of the kettle is 0.9 ⁇ 1.1MPaA, and the temperature is -55°C ⁇ -50°C.
  • the present invention has the following beneficial effects.
  • the product system of the present invention is flexible.
  • the proportions of SiF 4 , SiO 2 and HF are adjustable.
  • This invention uses forward osmosis to concentrate the aqueous solution containing fluorine and silicon (mainly fluosilicic acid), and its mass fraction can be as high as 60%. In this way, it is possible to produce HF while reducing the circulation amount of SiF 4 , reducing the by-product of SiO 2 , and also helping to suppress the generation of fluorosilicone ether in SiF 4 . This is beyond the reach of vacuum concentration.
  • the fluorine recovery rate of the present invention is high. Since forward osmosis is used to concentrate the absorption liquid, the concentration of the absorption liquid can be relatively low, thereby more thoroughly absorbing fluorine and silicon in the gas phase during the acidification process.
  • the present invention creatively focuses on the process essence of the reaction between silicon tetrafluoride and water, and seeks a solution before the formation of lattice fluorine. That is, first mix the concentrated solution and surfactant thoroughly in a microemulsion reactor, and then mix it with SiF 4 gas to improve the contact between the gas and liquid phases, thereby inhibiting the formation of lattice fluorine in silica (white carbon black). to form high-purity silica.
  • the use of microemulsion reactor can enhance the uniformity of material mixing, inhibit the generation of fluorosilicone and the entrainment of HF in SiF 4 , and provide reliable guarantee for obtaining high-purity SiF 4 .
  • the present invention increases extraction and liquid adsorption, which not only pre-removes a large number of metal ion impurities and organic matter in the system, but more importantly, takes into account the removal of anionic impurities including chlorine, thereby ensuring the reliability of product purity.
  • Figure 1 is a schematic flow diagram of the present invention
  • Figure 2 is a flow chart of the fluorine-containing gas absorption process.
  • This embodiment provides a method for graded utilization of fluorine and silicon resources in phosphate rock.
  • a method for hierarchically utilizing fluorine and silicon resources in phosphate rock may include the following steps.
  • Acidification Mix and react sulfuric acid or phosphoric acid with phosphate rock to generate dilute phosphoric acid or/and phosphate fertilizer, and at the same time produce tail gas containing fluorine and silicon.
  • Osmotic concentration Use a driving fluid and an acidic solution to perform an osmotic operation.
  • the driving fluid absorbs part of the solvent in the acidic solution to obtain a dilute solution; the concentration of the acidic solution increases to obtain a concentrated solution.
  • the osmosis operation is a forward osmosis method
  • the driving liquid is a phosphate solution or a phosphoric acid solution
  • the dilute solution includes a dilute phosphate solution or a dilute phosphoric acid solution.
  • the forward osmosis method is a membrane separation process that relies on the osmotic pressure difference on both sides of the selective permeability membrane as the driving force to spontaneously realize water transfer.
  • the two sides of the membrane are the driving liquid and the raw material liquid.
  • the osmotic pressures of the two are different.
  • the solvent can spontaneously pass through the membrane to the side with higher osmotic pressure until the osmotic pressure on both sides is balanced, but the solute does not pass through the membrane, thereby changing the solution.
  • Concentration is a countercurrent osmosis method. Compared with reverse osmosis, forward osmosis does not require high pressure and is an efficient and energy-saving concentration method.
  • Extraction Add the extraction phase to the fluorine-containing solution, mix thoroughly for extraction, and separate the phases to obtain the load phase and extraction phase. Remaining liquid.
  • the raffinate is the remaining solution obtained after the solution is extracted with the extraction phase.
  • the raffinate may be a preliminarily purified fluorosilicic acid solution.
  • Liquid adsorption removes impurities in the raffinate to obtain a refined solution.
  • Dehydration Add a dehydrating agent to the refined solution and mix thoroughly to obtain crude SiF 4 gas and HF-sulfuric acid solution.
  • the HF-sulfuric acid solution is stripped and distilled to produce anhydrous with a purity of not less than 99%. Hydrogen fluoride and by-product waste sulfuric acid.
  • Impurity removal The impurities in the crude SiF 4 gas are adsorbed through gaseous adsorption to obtain impurity removal gas.
  • the impurity-removing gas is a gas obtained by removing some impurities through gaseous adsorption.
  • the impurity removal gas is refined silicon tetrafluoride gas.
  • Low-temperature rectification perform low-temperature rectification on the impurity-removing gas to remove impurities with low and high boiling points to obtain impurity gas and SiF 4 with a purity of not less than 99%.
  • the impurity gas is SiF 4 containing impurities, for example, SiF 4 with a purity lower than 99%.
  • the dilute solution obtained in step (3) and the waste sulfuric acid obtained in step (7) are sent to step (1) to be mixed with phosphate rock; the waste gas obtained in step (4) is sent to step (2) ) is absorbed together with the tail gas; the impurity gas obtained in step (9) is passed into the concentrated solution in step (4) as SiF 4 gas.
  • step (1) phosphate rock reacts with sulfuric acid to produce calcium chloride, and superheated steam of no less than 140°C is introduced into the slurry to strip fluorosilicic acid to obtain the product calcium chloride and fluorine-containing diphosphate. Secondary steam, fluorine-containing secondary steam and the tail gas generated in step (1) are sent to step (2) for absorption.
  • step (1) dilute phosphoric acid is obtained after mixing sulfuric acid or phosphoric acid with phosphate rock, and the dilute phosphoric acid is concentrated to obtain fluorine-containing secondary steam and a product fertilizer phosphoric acid with a P 2 O 5 mass fraction of not less than 54%. ; The fluorine-containing secondary steam is sent to step (2) for absorption together with the tail gas generated in step (1).
  • step (2) adopts external cooling forced circulation three-stage countercurrent vacuum absorption, and each stage of absorption adopts the co-current contact form of upper-stage spray and lower-stage filler, and the droplet size of the spray is 100 to 300 ⁇ m.
  • the circulating fluid temperature of each stage shall not be higher than 60°C.
  • External cooling forced circulation three-stage countercurrent vacuum absorption refers to the use of evaporation three-effect countercurrent forced circulation production equipment for vacuum absorption. Counterflow is used between stages to obtain a higher concentration of solution; cocurrent flow is used within the stages to reduce fluid resistance; and Each stage of absorption adopts the co-current contact form of upper spray and lower filler, which can achieve rapid mass transfer and reduce mist entrainment.
  • External cooling means that the circulating absorption liquid is cooled by a heat exchanger before contacting the gas. The low temperature is conducive to the dissolution of the gas in the liquid.
  • the unabsorbed exhaust gas in step (2) is sent for deep absorption;
  • the absorbent used for deep absorption can include Na 2 CO 3 , NaHCO 3 or KOH solution, and the temperature for deep absorption is not higher than 40°C. .
  • the concentration operation of step (4) is performed in a microemulsion reactor.
  • the concentrated solution in the concentration operation of step (4), is first fully mixed with the surfactant, and then mixed with SiF 4 gas; the volume ratio of the surfactant to the concentrated solution is 1:200 ⁇ 1 :50.
  • surfactants can be the extraction phase of cationic extractions.
  • the extraction phase in step (5) consists of an extraction agent and a diluent.
  • the volume fraction of the extraction agent is not greater than 80%.
  • the diluent is kerosene, isopropyl ether, or C 6 to C 14 hydrocarbons. One or a mixture of several.
  • the extraction in step (5) includes cation extraction and anion extraction, and the loaded phase after cation extraction and anion extraction is washed, regenerated and then recycled.
  • the volume ratio of the extraction phase of cation extraction to the fluorine-containing solution is 0.5:1 to 6:1
  • the extraction agent of the extraction phase of cation extraction is organic phosphines, phospholipids, carboxylic acids, and sulfonic acids.
  • the volume of the extraction phase of anion extraction and the fluorine-containing solution is 0.5:1 to 6:1
  • the extraction agent of the extraction phase of anion extraction is an organic amine extraction agent.
  • the loaded phase after extraction of the extraction phase of cation extraction is washed with water and regenerated with 5% to 40% dilute sulfuric acid for recycling, wherein the volume ratio of the loading phase after extraction of the extraction phase of cation extraction to water is: 10:1 ⁇ 40:1, the volume ratio of the washed load phase to 5% ⁇ 40% dilute sulfuric acid is 10:1 ⁇ 40:1; the extraction phase of anion extraction, the loaded phase after extraction is washed with water and 2% ⁇ 25% ammonia water is recycled after regeneration.
  • the volume ratio of the load phase after extraction of the anion extraction phase to water is 10:1 ⁇ 40:1
  • the volume ratio of the load phase after washing to 2% ⁇ 25% ammonia water is 10:1 ⁇ 40:1; the residual liquid produced after two water washings is returned to step (2) for absorbing tail gas; the regeneration waste liquid produced after two regenerations is used for phosphate rock acidification or fertilizer production.
  • the liquid adsorption in step (6) includes activated carbon adsorption, cation adsorption and anion adsorption.
  • the activated carbon, cation adsorbent and anion adsorbent can be reused after being saturated by desorption and regeneration.
  • water is first used for desorption, and then a sodium hydroxide solution with a mass fraction of 5% to 10% is used for desorption.
  • the cationic adsorbent is desorbed and regenerated by first desorbing with water and then using a sulfuric acid solution with a mass fraction of 5% to 20%.
  • the anionic adsorbent is desorbed and regenerated by first desorbing with water, and then using 5% to 25% mass fraction of ammonia water for desorption.
  • the desorption temperature is 60-80°C; the desorption liquid formed by water desorption is returned to the step (2) to adsorb the tail gas; the desorption liquid formed by desorption of sodium hydroxide solution and desorption of ammonia water is used
  • the desorption solution formed by desorption of sulfuric acid solution is used for acidification of phosphate rock.
  • step (7) the purified solution and the dehydrating agent are dehydrated through two-stage countercurrent contact in the microemulsion reactor.
  • the dehydrating agent in step (7) is one or a mixture of sulfur trioxide, fuming sulfuric acid, and concentrated sulfuric acid with a mass fraction greater than 93%.
  • the gaseous adsorption in step (8) includes activated carbon adsorption, molecular sieve adsorption and modified adsorption.
  • the adsorbent is adsorbed, and activated carbon, molecular sieves and modified adsorbents can be reused after desorption and regeneration after adsorption saturation.
  • activated carbon and molecular sieves are desorbed and regenerated using absolute dry nitrogen. They are first desorbed at a temperature of 100-150°C and a pressure of 0.2-0.3MPaA. The desorbed gas is sent to step (4) for concentration of the concentrated solution. ; Then desorb at a temperature of 200 ⁇ 250°C and a pressure of 0.3 ⁇ 0.5MPaA, and the desorption gas is sent to fertilizer production.
  • activated carbon, molecular sieves and modified adsorbents are all desorbed and regenerated using a mixture of absolute dry nitrogen and ammonia-containing nitrogen with an ammonia volume fraction of 2% to 10%; the desorption temperature is greater than 100°C , the desorption pressure is not greater than 80KPaA; the desorption gas formed by absolute dry nitrogen is sent to the concentrated solution in step (4); the desorption gas formed by the mixed gas containing ammonia nitrogen is sent to the tail washing section of fertilizer production.
  • the modified adsorbent is porous alumina surface-modified with an organic amine, silica surface-modified with an organic amine, or porous polymer surface-modified with an organic amine.
  • the low-temperature rectification in step (9) includes one-stage distillation and two-stage distillation; the first-stage distillation first removes low-boiling point impurities, the tower top pressure is 0.95 ⁇ 1.15MPaA, and the temperature is -56°C ⁇ -51 °C, the tower still pressure is 1.0 ⁇ 1.2MPaA, the temperature is -51°C ⁇ -47°C; the second stage distillation removes high boiling point impurities, the tower top pressure is 0.85 ⁇ 1.05MPaA, the temperature is -60°C ⁇ -55°C, The pressure of the tower kettle is 0.9 ⁇ 1.1MPaA, and the temperature is -55°C ⁇ -50°C.
  • a method for graded utilization of fluorine and silicon elements in phosphate rock specifically includes the following steps.
  • Acidification Phosphate rock and sulfuric acid react according to the semi-aqueous-dihydrate method to obtain 38% P 2 O 5 fertilizer phosphoric acid, which is then concentrated to 55% P 2 O 5 .
  • concentration technology is an existing technology, that is, vacuum evaporation and concentration are used.
  • the fluorine-containing secondary steam generated during the concentration process and the tail gas generated by acidification are sent to step (2) for absorption.
  • the three-stage countercurrent absorption used in this embodiment refers to the use of external cooling forced circulation three-stage countercurrent vacuum absorption.
  • External cooling forced circulation three-stage countercurrent vacuum absorption refers to the use of evaporation three-effect countercurrent forced circulation production equipment for vacuum absorption. Counterflow is used between stages to obtain a higher concentration of solution; cocurrent flow is used within the stages to reduce fluid resistance; and Each stage of absorption adopts the co-current contact form of upper spray and lower filler, which can achieve rapid mass transfer and reduce mist entrainment.
  • External cooling means that the circulating absorption liquid is cooled by a heat exchanger before contacting the gas. The low temperature is conducive to the dissolution of the gas in the liquid.
  • the setting conditions are that the spray droplet size is 100 to 300 ⁇ m, and the temperature of the circulating fluid in each stage is not higher than 60°C.
  • FIG 2 which includes three absorption towers (T-1, T-2, T-3) placed side by side.
  • the fluorine-containing secondary steam passes through T-1 and T-2 in sequence.
  • T-3 is absorbed as exhaust gas, and is discharged driven by fan C-1.
  • Circulating fluid is based on It passes through T-3, T-2, T-1 and countercurrents with the fluorine-containing secondary steam for absorption.
  • the absorption tower there is an empty spray area at the top and a packing area at the bottom.
  • the circulating liquid After the circulating liquid enters the absorption tower, it forms a spray through the spray device in the tower, and then falls into the packing area to condense into liquid, achieving full contact and absorption with the fluorine-containing secondary steam.
  • the absorption liquid passes through the buffer tank V and the centrifugal pump P, it is cooled by the cooler H.
  • the cooled absorption liquid can enter the corresponding absorption tower for reabsorption, or it can enter the next-level absorption tower for absorption. In this way, the absorption liquid is concentrated, so the concentration of the absorption liquid can be relatively low, thereby more thoroughly absorbing the fluorine and silicon in the gas phase during the acidification process. Therefore, the fluorine recovery rate of the present invention is extremely high.
  • the following embodiments adopt the same absorption method, so no further description is given.
  • the volume ratio of the loaded phase after extraction by the cationic extraction phase to water is 10:1, and the loaded phase after washing is mixed with 5% dilute sulfuric acid.
  • the volume ratio of sulfuric acid is 10:1.
  • the loaded phase after extraction by the anionic extraction phase is washed with water and regenerated with 2% ammonia water and then recycled.
  • the volume ratio of the loaded phase after extraction by the anionic extraction phase to water is 10:1, and the volume ratio of the loaded phase after extraction with 2% ammonia water is 10:1.
  • the volume ratio of ammonia to water is 10:1.
  • Liquid adsorption After the initially purified fluorosilicic acid solution is deeply removed by activated carbon, cationic resin and anionic resin, a refined fluorosilicic acid solution is obtained. During regeneration, activated carbon, cationic resin and anionic resin are first washed with desalted water, and the washing water is returned to the absorption process of acidified exhaust gas. Then use 5% mass fraction of sodium hydroxide solution to clean the activated carbon, use 5% mass fraction of ammonia water to clean the anionic resin, and then use desalted water to rinse the activated carbon and anionic resin. The generated wastewater is sent to the exhaust gas of the phosphate fertilizer production line for absorption. The cationic resin is cleaned with 5% mass fraction of sulfuric acid solution, and then rinsed with desalted water, and the generated wastewater is sent to the acidification process. Among them, the desorption temperature is set to 60°C.
  • Dehydration Use 98% sulfuric acid and refined fluorosilicic acid solution in a microemulsion reactor to complete dehydration through two-stage countercurrent contact to obtain crude silicon tetrafluoride gas and a sulfuric acid solution containing hydrogen fluoride. The solution is stripped and defluorinated into waste sulfuric acid, which is sent to acidify the phosphate rock. After rectification of the stripped gas phase, anhydrous hydrogen fluoride is obtained.
  • Impurity removal through gaseous adsorption The crude silicon tetrafluoride gas is deeply removed by activated carbon, molecular sieves and porous alumina surface-modified with organic amines to obtain refined silicon tetrafluoride gas.
  • activated carbon and molecular sieves are desorbed and regenerated using absolute dry nitrogen. They are first desorbed at a temperature of 100°C and a pressure of 0.2MPaA. The desorption gas is sent to the step (4) for concentration of the concentrated solution; then it is desorbed at a temperature of 200°C. , desorption under a pressure of 0.3MPaA, and the desorption gas is sent to fertilizer production.
  • Activated carbon, molecular sieves and modified adsorbents are all desorbed and regenerated using a mixture of absolute dry nitrogen and ammonia-containing nitrogen with a volume fraction of 2% ammonia; the desorption temperature is 105°C and the desorption pressure is 80KPaA; absolute dry nitrogen is formed
  • the desorption gas is sent to the concentrated solution in step (4); the desorption gas formed by the mixed gas containing ammonia and nitrogen is sent to the tail washing section of fertilizer production.
  • the first stage of rectification removes low-boiling point impurities.
  • the tower top pressure is 0.95MPaA and the temperature is -56°C.
  • the tower bottom pressure is 1.0MPaA and the temperature is -51°C.
  • the second-stage distillation removes high-boiling point impurities.
  • the tower top pressure is 0.85MPaA and the temperature is -60°C.
  • the tower bottom pressure is 0.9MPaA and the temperature is -55°C.
  • a method for graded utilization of fluorine and silicon elements in phosphate rock specifically includes the following steps.
  • Acidification Phosphate rock and sulfuric acid react according to the dihydrate method to obtain 23% P 2 O 5 fertilizer phosphoric acid, which is then concentrated to 55% P 2 O 5 .
  • concentration technology is an existing technology, that is, vacuum evaporation and concentration are used.
  • the fluorine-containing secondary steam generated during the concentration process and the tail gas generated by acidification are sent to step (2) for absorption.
  • Osmosis concentration Use the forward osmosis method, use saturated monoammonium phosphate solution as the driving fluid, and countercurrent osmosis to concentrate the fluosilicic acid solution from a mass fraction of 18% to 47%, and the produced dilute ammonium phosphate is returned to the phosphate fertilizer production line.
  • the volume ratio of sulfuric acid is 20:1; the load phase after extraction by the anion extraction phase is washed with water and regenerated with 12% ammonia water and recycled, wherein the volume ratio of the load phase after extraction by the anion extraction phase and water is 20:1 , the volume ratio of the washed load phase to 10% ammonia water is 20:1.
  • Liquid adsorption After the initially purified fluorosilicic acid solution is deeply removed by activated carbon, cationic resin and anionic resin, a refined fluorosilicic acid solution is obtained. During regeneration, activated carbon, cationic resin and anionic resin are first washed with desalted water, and the washing water is returned to the absorption process of acidified exhaust gas. Then use 10% mass fraction of sodium hydroxide solution to clean the activated carbon, use 10% mass fraction of ammonia water to clean the anionic resin, and then use desalted water to rinse the activated carbon and anionic resin. The generated wastewater is sent to the exhaust gas of the phosphate fertilizer production line for absorption. The cationic resin is cleaned with 20% mass fraction of sulfuric acid solution, and then rinsed with desalted water, and the generated wastewater is sent to the acidification process. Among them, the desorption temperature is set to 70°C.
  • Dehydration Use 101% sulfur trioxide solution and refined fluorosilicic acid solution in a microemulsion reactor to complete dehydration through two-stage countercurrent contact to obtain crude silicon tetrafluoride gas and a sulfuric acid solution containing hydrogen fluoride. The solution is stripped and defluorinated into waste sulfuric acid, which is sent to acidify the phosphate rock. After rectification of the stripped gas phase, anhydrous hydrogen fluoride is obtained.
  • Impurity removal through gaseous adsorption The crude silicon tetrafluoride gas is deeply removed by activated carbon, molecular sieves and porous polymers surface-modified with organic amines to obtain refined silicon tetrafluoride gas.
  • activated carbon and molecular sieves are desorbed and regenerated using absolute dry nitrogen. They are first desorbed at a temperature of 120°C and a pressure of 0.2MPaA. The desorption gas is sent to the step (4) for concentration of the concentrated solution; then it is desorbed at a temperature of 220°C. , desorption under a pressure of 0.4MPaA, and the desorption gas is sent to fertilizer production.
  • Activated carbon, molecular sieves and modified adsorbents are all desorbed and regenerated using a mixture of absolute dry nitrogen and ammonia-containing nitrogen with a volume fraction of 5% ammonia; the desorption temperature is 110°C and the desorption pressure is 75KPaA; absolute dry nitrogen is formed
  • the desorption gas is sent to the concentrated solution in step (4); the desorption gas formed by the mixed gas containing ammonia and nitrogen is sent to the tail washing section of fertilizer production.
  • the first stage of distillation removes low-boiling point impurities
  • the tower top pressure is 1.00MPaA
  • the temperature is -55°C
  • the tower bottom pressure is 1.0MPaA
  • the temperature is -50°C.
  • the second-stage distillation removes high-boiling impurities.
  • the tower top pressure is 1.00MPaA and the temperature is -58°C.
  • the tower bottom pressure is 1.00MPaA and the temperature is -54°C.
  • a method for graded utilization of fluorine and silicon elements in phosphate rock specifically includes the following steps.
  • Acidification Phosphate rock reacts with sulfuric acid to produce ordinary calcium, and superheated steam at 140°C is introduced into the slurry. Fluorosilicic acid. The tail gas generated by the acidification of the fluorine-containing secondary steam generated in this process is sent to step (2) for absorption.
  • Osmosis concentration Use the forward osmosis method, use saturated monoammonium phosphate solution as the driving fluid, and countercurrent osmosis to concentrate the fluosilicic acid solution from a mass fraction of 25% to 54%, and the produced dilute ammonium phosphate is returned to the phosphate fertilizer production line.
  • the volume ratio of sulfuric acid is 30:1; the load phase after extraction by the anion extraction phase is washed with water and regenerated with 20% ammonia water for recycling, wherein the volume ratio of the load phase after extraction by the anion extraction phase and water is 30:1 , the volume ratio of the washed load phase to 20% ammonia water is 30:1.
  • Liquid adsorption After the initially purified fluorosilicic acid solution is deeply removed by activated carbon, cationic resin and anionic resin, a refined fluorosilicic acid solution is obtained. During regeneration, activated carbon, cationic resin and anionic resin are first washed with desalted water, and the washing water is returned to the absorption process of acidified exhaust gas. Then use 5% mass fraction of sodium hydroxide solution to clean the activated carbon, use 20% mass fraction of ammonia water to clean the anionic resin, and then use desalted water to rinse the activated carbon and anionic resin. The generated wastewater is sent to the exhaust gas of the phosphate fertilizer production line for absorption. The cationic resin is cleaned with 18% mass fraction of sulfuric acid solution, and then rinsed with desalted water, and the generated wastewater is sent to the acidification process. Among them, the desorption temperature is set to 70°C.
  • Dehydration Use 93% sulfuric acid and refined fluorosilicic acid solution in a microemulsion reactor to complete dehydration through two-stage countercurrent contact to obtain crude silicon tetrafluoride gas and a sulfuric acid solution containing hydrogen fluoride. The solution is stripped and defluorinated into waste sulfuric acid, which is sent to acidify the phosphate rock. After rectification of the stripped gas phase, anhydrous hydrogen fluoride is obtained.
  • Impurity removal through gaseous adsorption The crude silicon tetrafluoride gas is deeply removed by activated carbon, molecular sieves, and silica surface-modified with organic amines to obtain refined silicon tetrafluoride gas.
  • activated carbon and molecular sieves are desorbed and regenerated using absolute dry nitrogen, first at a temperature of 140°C and a pressure of 0.25MPaA.
  • the desorption gas is sent to the step (4) for concentration of the concentrated solution; then it is desorbed at a temperature of 240°C and a pressure of 0.4MPaA, and the desorption gas is sent to fertilizer production.
  • Activated carbon, molecular sieves and modified adsorbents are all desorbed and regenerated using a mixture of absolute dry nitrogen and ammonia-containing nitrogen with an ammonia volume fraction of 8%; the desorption temperature is 114°C and the desorption pressure is 75KPaA; absolute dry nitrogen is formed
  • the desorption gas is sent to the concentrated solution in step (4); the desorption gas formed by the mixed gas containing ammonia and nitrogen is sent to the tail washing section of fertilizer production.
  • the first stage of distillation removes low-boiling point impurities.
  • the tower top pressure is 1.10MPaA and the temperature is -52°C.
  • the tower bottom pressure is 1.1MPaA and the temperature is -48°C.
  • the second-stage distillation removes high-boiling impurities.
  • the tower top pressure is 1.05MPaA and the temperature is -56°C.
  • the tower bottom pressure is 1.00MPaA and the temperature is -52°C.
  • a method for graded utilization of fluorine and silicon elements in phosphate rock specifically includes the following steps.
  • Osmosis concentration Use the forward osmosis method, use saturated monoammonium phosphate solution as the driving fluid, and countercurrent osmosis to concentrate the fluosilicic acid solution from 20% to 50% mass fraction, and the produced dilute ammonium phosphate is returned to the phosphate fertilizer production line.
  • the volume ratio of sulfuric acid is 40:1; the load phase after extraction by the anion extraction phase is washed with water and regenerated with 25% ammonia water and then recycled, wherein the volume ratio of the load phase after extraction by the anion extraction phase and water is 40:1 , the volume ratio of the washed load phase to 25% ammonia water is 40:1.
  • Liquid adsorption After the initially purified fluorosilicic acid solution is deeply removed by activated carbon, cationic resin and anionic resin, a refined fluorosilicic acid solution is obtained. During regeneration, activated carbon, cationic resin and anionic resin are first washed with desalted water, and the washing water is returned to the absorption process of acidified exhaust gas. Then use 5% mass fraction of sodium hydroxide solution to clean the activated carbon, use 25% mass fraction of ammonia water to clean the anionic resin, and then use desalted water to rinse the activated carbon and anionic resin. The generated wastewater is sent to the tail gas of the phosphate fertilizer production line for absorption. The cationic resin is cleaned with 15% mass fraction of sulfuric acid solution, and then rinsed with desalted water, and the generated wastewater is sent to the acidification process. Among them, the desorption temperature is set to 80°C.
  • Dehydration Use 98.3% sulfuric acid and refined fluorosilicic acid solution in a microemulsion reactor to complete dehydration through two-stage countercurrent contact to obtain crude silicon tetrafluoride gas and a sulfuric acid solution containing hydrogen fluoride.
  • the solution is stripped and defluorinated into waste sulfuric acid, which is sent to acidify the phosphate rock. After rectification of the stripped gas phase, anhydrous hydrogen fluoride is obtained.
  • Impurity removal through gaseous adsorption The crude silicon tetrafluoride gas is sequentially deeply removed by activated carbon, molecular sieves and organic amine surface-modified porous alumina to obtain refined silicon tetrafluoride gas.
  • activated carbon and molecular sieves are desorbed and regenerated using absolute dry nitrogen. They are first desorbed at a temperature of 150°C and a pressure of 0.3MPaA. The desorption gas is sent to the step (4) for concentration of the concentrated solution; then it is desorbed at a temperature of 250°C. , desorption under a pressure of 0.5MPaA, and the desorption gas is sent to fertilizer production.
  • Activated carbon, molecular sieves and modified adsorbents are all desorbed and regenerated using a mixture of absolute dry nitrogen and ammonia-containing nitrogen with a volume fraction of 10% ammonia; the desorption temperature is 110°C and the desorption pressure is 80KPaA; absolute dry nitrogen is formed
  • the desorption gas is sent to the concentrated solution in step (4); the desorption gas formed by the mixed gas containing ammonia and nitrogen is sent to the tail washing section of fertilizer production.
  • the first stage of distillation removes low-boiling point impurities.
  • the tower top pressure is 1.15MPaA and the temperature is -51°C.
  • the tower bottom pressure is 1.0 ⁇ 1.2MPaA and the temperature is -47°C.
  • the second-stage distillation removes high-boiling impurities.
  • the tower top pressure is 1.05MPaA and the temperature is -55°C.
  • the tower bottom pressure is 1.10MPaA and the temperature is -50°C.
  • this application uses specific words to describe the embodiments of the application.
  • “one embodiment”, “an embodiment”, and/or “some embodiments” means a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that “one embodiment” or “an embodiment” or “an alternative embodiment” mentioned twice or more at different places in this specification does not necessarily refer to the same embodiment. .
  • this application Certain features, structures or characteristics of one or more embodiments may be combined appropriately.
  • numbers are used to describe the quantities of components and properties. It should be understood that such numbers used to describe the embodiments are modified by the modifiers "about”, “approximately” or “substantially” in some examples. Grooming. Unless otherwise stated, “about,” “approximately,” or “substantially” means that the stated number is allowed to vary by ⁇ 20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximations that may vary depending on the desired features of the individual embodiment. In some embodiments, numerical parameters should account for the specified number of significant digits and use general digit preservation methods. Although the numerical fields and parameters used to confirm the breadth of the ranges in some embodiments of the present application are approximations, in specific embodiments, such numerical values are set as accurately as feasible.

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Abstract

本说明书具体公开了一种分级利用磷矿石中氟、硅资源的方法。在磷矿石与硫酸反应制得普钙或重钙或肥料磷酸的同时，产生含氟、硅元素的尾气。该尾气被水吸收后，形成含有HF和H2SiF6的溶液，对该溶液提浓、过滤，获得SiO2和高浓度的H2SiF6溶液；再将高浓度的H2SiF6溶液经萃取、吸附、脱水后，获得粗SiF4和含HF和H2SO4的溶液；粗SiF4经吸附、精馏后，获得5N纯度的SiF4，同时，富集杂质的SiF4返回前述的提浓、过滤步骤与含有HF和H2SiF6溶液反应生成H2SiF6和SiO2。含HF的H2SO4溶液经汽提、精馏分离后，获得高纯HF和废硫酸。废硫酸用于与前述的磷矿的反应。该方法可实现零排放零污染，并且产品体系灵活，SiF4、SiO2、HF三种产品的比例可调。

Description

一种分级利用磷矿石中氟、硅资源的方法
交叉引用
本申请要求2022年4月20日提交的中国专利申请202210413670.0的优先权，其全部内容通过引用并入本文。
技术领域
本发明涉及氟、硅化合物分离纯化技术领域，具体而言，涉及一种以磷矿石为原料，在生产磷酸、磷肥的过程中回收并提纯氟、硅化合物的分级利用磷矿石中氟、硅资源的方法。
背景技术
我国每年开采的磷矿石量达5000多万吨，大部分通过湿法工艺——磷矿与硫酸(少数使用硝酸或盐酸)用来制作磷肥、磷酸、磷酸盐。湿法工艺过程中会产生大量的含氟、硅的气体，直接排出会严重污染环境。大部分磷肥企业只能将含氟、硅的气体用水吸收生成氟硅酸，仅把废气转化成废水。国内湿法磷酸的产量每年1000万吨以上，副产氟硅酸——以15％含量计约375万吨。少数有实力的磷肥企业将氟硅酸转化成氟硅酸钠。国内仅有个别企业利用磷矿伴生氟资源成功生产出无水氟化氢，取得可观的经济效益和环境效益，但副产白炭黑的利用不足。由于没有充分的回收利用含氟、硅的气体，每年磷肥尾气浪费掉的氟资源有150多万吨，远大于国内每年萤石生产量中氟的总量。
氟硅酸是回收磷矿石中氟、硅资源工艺的重要中间产物，其浓度越高，越有利于后续处理。至今，已有多家磷肥企业在该领域长期实践，一般是通过管道喷淋吸收，最终获得的氟硅酸浓度在质量分数18％左右，要维持较高的氟回收率和较高的氟硅酸溶液浓度的技术难度偏大。其中，由氟硅酸制备无水氟化氢工艺较为成熟，但是该制备工程中获得的二氧化硅往往含有10％～20％的氟元素，以致该二氧化硅的应用大大受限。目前探索含氟的二氧化硅的脱氟提纯工艺中，基本都没有办法减少二氧化硅生成过程中夹带的氟元素。
在氟硅酸生产无水氟化氢或氟盐工艺中，二氧化硅一般是四氟化硅水化过程产生的，其夹带的氟包括两类：1、游离氟，约占70％，主要是粘附在二氧化硅表面的氟硅酸，可通过漂洗除去。2、晶格氟，约占30％，是由于四氟化硅气泡与水接触时气泡内侧的Si—F官能团未来得及与水接触反应就被气液界面反应生成的Si—O键网络所 包围导致的。由于晶格氟被坚固的Si—O键网络包围保护，故晶格氟一旦形成，物理洗涤无法除去，须通过化学方法松动包围的Si—O键，才行实现物质的进出，从而为分离创造条件。现有的文献和专利基本遵循该思路研究脱氟工艺，而没有着眼四氟化硅与水反应的过程本质，在晶格氟形成之前，寻找解决途径。
相较改良西门子法，硅烷法生产晶体硅更加节能。随着硅烷法技术进步，人们对四氟化硅的关注日益剧增，因为四氟化硅是休斯法生产硅烷的重要原料之一。国内已有业内人士在尝试以四氟化硅为原料生产多晶硅，并将目光投向了磷矿中的氟、硅资源。但是，其生产工艺也或多或少存在一些缺陷。因此，期望提出一种分级利用磷矿石中氟、硅资源的方法，该方法能够充分利用磷矿石中的氟、硅资源，减少资源浪费。
发明内容
本发明旨在提供一种从磷矿石中高效且经济的提取氟、硅元素，并获得高纯产品的生产工艺。该生产工艺也适用于处理其他含氟、硅的磷酸盐。
为实现上述目的，本发明采用的技术方案如下。
一种分级利用磷矿石中氟、硅资源的方法，其特征在于，包括以下步骤。
步骤(1)，酸化：将硫酸或磷酸与磷矿混合反应，生成稀磷酸或/和磷肥，同时产生含氟、硅的尾气，尾气的主要成分是水蒸气和气态的氟硅酸。
其中，若得到的是稀磷酸，浓缩后，可得到含氟二次蒸汽和P2O5质量分数不低于54％的肥料磷酸；并且，得到的磷酸浓度越高，那么逸出的氟越多。若磷矿与硫酸按生产普钙反应，向料浆中通入不低于140℃的过热蒸汽汽提氟硅酸，可直接得到产品普钙和含氟二次蒸汽；这两种方式得到的所述含氟二次蒸汽与步骤(1)产生的所述尾气一起送至步骤(2)吸收。
步骤(2)，吸收：用水吸收所述尾气和含氟二次蒸汽，得到含氟、硅的酸性溶液。
在一些实施例中，吸收可以为外降温强制循环三级逆流真空吸收。
此处，未被吸收的尾气等被送去深度吸收；深度吸收采用的吸收剂Na2CO3、NaHCO3或KOH溶液，设置温度不高于40℃，反应生成对应沉淀盐，实现深度吸收，满足环保。
步骤(3)，渗透增浓：利用磷酸盐溶液或磷酸溶液与所述酸性溶液进行正渗透操作，磷酸盐溶液或磷酸溶液吸收酸性溶液中的部分溶剂，得到稀酸溶液或稀盐溶液， 得到的稀酸溶液送入步骤(1)中与磷矿混合；所述酸性溶液浓度增加，得到浓溶液。
氟硅酸和水的沸点相差不大，蒸发浓缩的难度很大，本发明创新采用正渗透操作，将氟硅酸浓缩到质量分数45～60％的氟硅酸，为后续操作提供巨大的弹性。选用磷酸盐溶液或磷酸溶液做驱动液便于驱动液在磷酸、磷肥生产线中实现再生和循环。
步骤(4)，提浓过滤：将浓溶液与氟化硅气体通入微乳反应器中进行提浓操作，以继续提高所述浓溶液的浓度；然后再进行过滤分离，得到SiO2固体、含氟溶液和废气，所述废气送入步骤(2)中与尾气一起被吸收。
应当注意的是，在微乳反应器中，本发明创造性的先将所述浓溶液与表面活性剂充分混合，再与SiF4气体混合；这是因为四氟化硅水化过程极易产生晶格氟，由于晶格氟被坚固的Si—O键网络包围保护，故晶格氟一旦形成，物理洗涤无法除去，须通过化学方法松动包围的Si—O键，才能实现物质的进出，从而为分离创造条件。现有技术都是在生成晶格氟之后才想方法去除它，难度极大。而本发明创造性的着眼四氟化硅与水反应的过程本质，在晶格氟形成之前，寻找解决途径。即先将所述浓溶液与表面活性剂充分混合，利用表面活性剂降低表面张力，使两相表面的接触面积更大，倾向于铺展，抑制气泡内不与液体接触的情况，此后再与SiF4气体混合，以改善气液两相的接触，从而抑制二氧化硅(白炭黑)中晶格氟的形成，进而得到高纯度的二氧化硅。为达到更好的效果，所述表面活性剂与所述浓溶液的体积比为1:200～1:50。
步骤(5)，萃取：在所述含氟溶液中加入萃取相，并充分混合萃取，分相得到负载相和萃余液。其中，萃取相由萃取剂和稀释剂组成，所述萃取剂的体积分数不大于80％，所述稀释剂是煤油、异丙醚、C6～C14的烃中的一种或几种的混合物。在一些实施例中，该萃取操作包含阳离子萃取和阴离子萃取，且阳离子萃取和阴离子萃取后的负载相均经洗涤、再生后循环使用。上述步骤(4)中的表面活性剂也可直接作为阳离子萃取的萃取相。
具体来说，所述阳离子萃取的萃取相与含氟溶液的体积比为0.5:1～6:1，阳离子萃取的萃取相的萃取剂是有机膦类、磷脂类、羧酸类、磺酸类有机溶剂中的一种或几种的混合物；所述阴离子萃取的萃取相与含氟溶液的体积比为0.5:1～6:1，阴离子萃取的萃取相的萃取剂是有机胺类萃取剂。
所述阳离子萃取相萃取后的负载相经水洗涤和5％～40％稀硫酸再生后循环使用。其中，阳离子萃取相萃取后的负载相与水的体积比为10:1～40:1，洗涤后的负载相与5％～40％稀硫酸的体积比为10:1～40:1。所述阴离子萃取相萃取后的负载相经水洗涤和 2％～25％氨水再生后循环使用。其中，阴离子萃取相萃取后的负载相与水的体积比为10:1～40:1，洗涤后的负载相与2％～25％氨水的体积比为10:1～40:1。两次水洗涤后产生的洗余液返回步骤(2)中用于吸收尾气；两次再生后产生的再生废液用于磷矿酸化或肥料生产。
步骤(6)，液态吸附：吸附脱除所述萃余液里的杂质，得到精制溶液；该吸附包括活性炭吸附、阳离子吸附和阴离子吸附，活性炭、阳离子吸附剂和阴离子吸附剂吸附饱和后经脱附再生得以重复使用。
在一些实施例中，脱附再生活性炭时，先用水脱附，再用5％～10％质量分数的氢氧化钠溶液脱附；脱附再生阳离子吸附剂，先用水脱附，再用5％～20％质量分数的硫酸溶液脱附；脱附再生阴离子吸附剂，先用水脱附，再用5％～25％质量分数的氨水脱附；脱附温度60～80℃；由水脱附形成的脱附液返回所述步骤(2)中吸附所述尾气；氢氧化钠溶液脱附、氨水脱附所形成的脱附液用于肥料生产，硫酸溶液脱附所形成的脱附液用于磷矿酸化。
步骤(7)，脱水：将所述精制溶液与脱水剂在微乳反应器内充分混合，通过两级逆流充分接触，吸收精制溶液中的水分，促使氟硅酸分解，得到粗SiF4气体和HF-硫酸溶液，将所述HF-硫酸溶液经汽提、精馏分离产出纯度不低于99％的高纯无水氟化氢和副产物废硫酸，废硫酸送入步骤(1)中与磷矿混合。其中，脱水剂是三氧化硫、发烟硫酸、质量分数大于93％的浓硫酸中的一种或几种的混合物。采用微乳反应器完成该脱水过程是为了强化物料混合的均匀性，抑制氟硅醚的产生。
步骤(8)，除杂：通过气态吸附来吸附所述粗SiF4气体中的杂质，得到除杂气。其气态吸附包括活性炭吸附、分子筛吸附和改性吸附剂吸附，且活性炭、分子筛和改性吸附剂吸附饱和后经脱附再生得以重复使用。所述改性吸附剂是被有机胺表面改性的多孔氧化铝、被有机胺表面改性的二氧化硅或被有机胺表面改性的多孔高分子聚合物。
在一些实施例中，所述活性炭和分子筛采用绝干氮气脱附再生，先在温度100～150℃、压力0.2～0.3MPaA下脱附，脱附气送至所述步骤(4)中用于浓溶液提浓；再在温度200～250℃，压力0.3～0.5MPaA下脱附，脱附气送去肥料生产。所述活性炭和分子筛是采用绝干氮气和氨气体积分数为2％～10％的含氨氮气的混合气进行脱附再生。改性吸附剂的脱附剂是绝干氮气和氨气体积分数为2％～10％的含氨氮气的混合气。脱附温度大于100℃，脱附压力不大于80KPaA。绝干氮气形成的脱附气被送至氟硅酸溶液的提浓过滤步骤；含氨氮气的混合气形成的脱附气送去肥料生产的尾洗工段。
步骤(9)，低温精馏：对除杂气进行低温精馏，深度脱除低沸点、高沸点的杂质，得到杂质气，及纯度不低于99％的高纯SiF4。其中，杂质气作为SiF4气体通入步骤(4)中的浓溶液中。具体来说，所述低温精馏包括一段精馏和二段精馏；所述一段精馏先脱低沸点杂质，塔顶压力为0.95～1.15MPaA、温度为-56℃～-51℃，塔釜压力为1.0～1.2MPaA、温度为-51℃～-47℃；所述二段精馏再脱高沸点杂质，塔顶压力为0.85～1.05MPaA、温度为-60℃～-55℃，塔釜压力为0.9～1.1MPaA、温度为-55℃～-50℃。
与现有技术相比，本发明具有以下有益效果。
1、本发明全系统整合。将磷矿湿法制酸、制肥、制氟、硅产品全系统整合，充分合理的利用生产高纯氟、硅产品时副产的“三废”，实现零排放、零污染。这是单独使用氟硅酸制四氟化硅无法实现的。
2、本发明产品体系灵活。SiF4、SiO2、HF三种产品的比例可调。
3、本发采用正渗透浓缩含氟、硅的水溶液(主要是氟硅酸)，其质量分数可高达60％。如此便可实现生产HF的同时，减少SiF4循环量，减少SiO2副产量，还有利于抑制SiF4中氟硅醚的生成。这是真空浓缩所不及的。
4、本发明氟回收率高。由于采用了正渗透来浓缩吸收液，故吸收液的浓度可相对偏低，从而更彻底的吸收酸化过程中气相里的氟、硅。
5、本发明创造性的着眼四氟化硅与水反应的过程本质，在晶格氟形成之前，寻找解决途径。即先将所述浓溶液与表面活性剂在微乳反应器充分混合，再与SiF4气体混合，以改善气液两相的接触，从而抑制二氧化硅(白炭黑)中晶格氟的形成，进而得到高纯度的二氧化硅。同时，微乳反应器的使用，可以强化物料混合的均匀性，抑制SiF4中氟硅醚的生成和HF的夹带，为获得高纯的SiF4提供可靠的保障。
6、本发明增加萃取和液态吸附，不仅预脱除了系统中大量的金属离子杂质和有机质，更重要的是考虑了包括氯元素在内的阴离子杂质的脱除，从而确保产品纯度的可靠。
附图说明
本说明书将以示例性实施例的方式进一步说明，这些示例性实施例将通过附图进行详细描述。这些实施例并非限制性的，在这些实施例中，相同的编号表示相同的结构，其中：
图1为本发明的流程示意图；
图2为含氟气体吸收工艺流程图。
具体实施方式
为了更清楚地说明本说明书实施例的技术方案，下面将对实施例描述中所需要使用的附图作简单的介绍。显而易见地，下面描述中的附图仅仅是本说明书的一些示例或实施例，对于本领域的普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图将本说明书应用于其它类似情景。除非从语言环境中显而易见或另做说明，图中相同标号代表相同结构或操作。
如本说明书和权利要求书中所示，除非上下文明确提示例外情形，“一”、“一个”、“一种”和/或“该”等词并非特指单数，也可包括复数。一般说来，术语“包括”与“包含”仅提示包括已明确标识的步骤、元素和/或物质，而这些步骤、元素和/或物质不构成一个排它性的罗列，方法或者平台也可能包含其它的步骤、元素和/或物质。
本发明的术语“包括”以及它的任何变形，意图在于覆盖不排他的包含。例如包含了一系列步骤的过程和方法没有限定于已列出的步骤，而是可选地还包括没有列出的步骤，或可选地还包括对于这些过程和方法固有的其它步骤。
本实施例提供了一种分级利用磷矿石中氟、硅资源的方法。
在一些实施例中，一种分级利用磷矿石中氟、硅资源的方法可以包括以下步骤。
(1)酸化：将硫酸或磷酸与磷矿混合反应，生成稀磷酸或/和磷肥，同时产生含氟、硅的尾气。
(2)吸收：用水吸收所述尾气，得到含氟、硅的酸性溶液。
(3)渗透增浓：利用驱动液与酸性溶液进行渗透操作，驱动液吸收酸性溶液中的部分溶剂，得到稀溶液；酸性溶液浓度增加，得到浓溶液。其中，渗透操作是正渗透法，驱动液为磷酸盐溶液或磷酸溶液，稀溶液包括稀磷酸盐溶液或稀磷酸溶液。
正渗透法是一种依靠选择性渗透膜两侧的渗透压差为驱动力自发实现水传递的膜分离过程。膜两侧分别是驱动液与原料液，二者的渗透压不同，溶剂可自发通过膜向渗透压高的一侧传递，直至两侧渗透压平衡，而溶质不通过该膜，从而实现改变溶液浓度，是一种逆流渗透法。与反渗透相比，正渗透无需高压，是一种高效节能的浓缩方法。
(4)提浓过滤：向浓溶液中通入氟化硅气体进行提浓操作，以继续提高浓溶液的浓度；然后过滤分离，得到SiO2固体、含氟溶液和废气。
(5)萃取：在含氟溶液中加入萃取相，并充分混合萃取，分相得到负载相和萃 余液。萃余液为溶液经萃取相萃取后得到的剩余溶液。在一些实施例中，萃余液可以是初步净化的氟硅酸溶液。
(6)液态吸附：吸附脱除萃余液里的杂质，得到精制溶液。
(7)脱水：在精制溶液中加入脱水剂并充分混合，得到粗SiF4气体和HF-硫酸溶液，将HF-硫酸溶液经汽提、精馏分离产出纯度不低于99％的无水氟化氢和副产物废硫酸。
(8)除杂：通过气态吸附来吸附粗SiF4气体中的杂质，得到除杂气。除杂气为通过气态吸附除去部分杂质后的气体。在一些实施例中，除杂气为精四氟化硅气体。
(9)低温精馏：对除杂气进行低温精馏，脱除低沸点、高沸点的杂质，得到杂质气，及纯度不低于99％的SiF4。杂质气为含杂质的SiF4，例如，纯度低于99％的SiF4。
在一些实施例中，步骤(3)中得到的稀溶液和步骤(7)中得到的废硫酸均送入步骤(1)中与磷矿混合；步骤(4)得到的废气送入步骤(2)中与尾气一起被吸收；步骤(9)得到的杂质气作为SiF4气体通入步骤(4)中的浓溶液中。
在一些实施例中，步骤(1)中，磷矿与硫酸按生产普钙反应，向料浆中通入不低于140℃的过热蒸汽汽提氟硅酸，得到产品普钙和含氟二次蒸汽，含氟二次蒸汽与步骤(1)产生的尾气一起送至步骤(2)吸收。
在一些实施例中，步骤(1)硫酸或磷酸与磷矿混合后得到稀磷酸，将该稀磷酸浓缩，得到含氟二次蒸汽和P2O5质量分数不低于54％的产品肥料磷酸；含氟二次蒸汽与步骤(1)产生的尾气一起送至步骤(2)吸收。
在一些实施例中，步骤(2)采用外降温强制循环三级逆流真空吸收，且每一级吸收均采用上段喷雾、下段填料的并流接触形式，喷雾的雾滴粒径为100～300μm，每级循环液温度不高于60℃。
外降温强制循环三级逆流真空吸收是指采用蒸发三效逆流强制循环生产装置进行真空吸收，级间采用逆流，以获得较高浓度的溶液；级内采用并流，以减小流体阻力；且每一级吸收均采用上段喷雾、下段填料的并流接触形式，可实现迅速传质并较少雾沫夹带。外降温则是指循环吸收液经过换热器降温后再与气体接触，低温有利于气体溶于液体中。
在一些实施例中，步骤(2)中未被吸收的尾气被送去深度吸收；深度吸收采用的吸收剂可以包括Na2CO3、NaHCO3或KOH溶液，深度吸收的温度不高于40℃。
在一些实施例中，所述步骤(4)的提浓操作在微乳反应器内进行。
在一些实施例中，在步骤(4)的提浓操作中，将浓溶液先与表面活性剂充分混合，再与SiF4气体混合；表面活性剂与浓溶液的体积比为1:200～1:50。在一些实施例中，表面活性剂可以为阳离子萃取的萃取相。
在一些实施例中，步骤(5)中的萃取相由萃取剂和稀释剂组成，萃取剂的体积分数不大于80％，稀释剂是煤油、异丙醚、C6～C14的烃中的一种或几种的混合物。
在一些实施例中，步骤(5)的萃取包含阳离子萃取和阴离子萃取，且阳离子萃取和阴离子萃取后的负载相均经洗涤、再生后循环使用。
在一些实施例中，阳离子萃取的萃取相与含氟溶液的体积比为0.5:1～6:1，阳离子萃取的萃取相的萃取剂是有机膦类、磷脂类、羧酸类、磺酸类有机溶剂中的一种或几种的混合物；阴离子萃取的萃取相与含氟溶液的体积为0.5:1～6:1，阴离子萃取的萃取相的萃取剂是有机胺类萃取剂。
在一些实施例中，阳离子萃取的萃取相萃取后的负载相经水洗涤和5％～40％稀硫酸再生后循环使用，其中，阳离子萃取的萃取相萃取后的负载相与水的体积比为10:1～40:1，洗涤后的负载相与5％～40％稀硫酸的体积比为10:1～40:1；阴离子萃取的萃取相萃取后的负载相经水洗涤和2％～25％氨水再生后循环使用，其中，阴离子萃取的萃取相萃取后的负载相与水的体积比为10:1～40:1，洗涤后的负载相与2％～25％氨水的体积比为10:1～40:1；两次水洗涤后产生的洗余液返回步骤(2)中用于吸收尾气；两次再生后产生的再生废液用于磷矿酸化或肥料生产。
在一些实施例中，步骤(6)中液态吸附包括活性炭吸附、阳离子吸附和阴离子吸附，活性炭、阳离子吸附剂和阴离子吸附剂吸附饱和后经脱附再生得以重复使用。在一些实施例中，脱附再生活性炭时，先用水脱附，再用5％～10％质量分数的氢氧化钠溶液脱附。在一些实施例中，脱附再生阳离子吸附剂，先用水脱附，再用5％～20％质量分数的硫酸溶液脱附。在一些实施例中，脱附再生阴离子吸附剂，先用水脱附，再用5％～25％质量分数的氨水脱附。其中，脱附温度为60～80℃；由水脱附形成的脱附液返回所述步骤(2)中吸附所述尾气；氢氧化钠溶液脱附、氨水脱附所形成的脱附液用于肥料生产，硫酸溶液脱附所形成的脱附液用于磷矿酸化。
在一些实施例中，步骤(7)中精制溶液与脱水剂在微乳反应器内通过两级逆流接触完成脱水。在一些实施例中，步骤(7)中的脱水剂是三氧化硫、发烟硫酸、质量分数大于93％的浓硫酸中的一种或几种的混合物。
在一些实施例中，步骤(8)中气态吸附包括活性炭吸附、分子筛吸附和改性吸 附剂吸附，且活性炭、分子筛和改性吸附剂吸附饱和后经脱附再生得以重复使用。
在一些实施例中，活性炭和分子筛采用绝干氮气脱附再生，先在温度100～150℃、压力0.2～0.3MPaA下脱附，脱附气送至步骤(4)中用于浓溶液提浓；再在温度200～250℃，压力0.3～0.5MPaA下脱附，脱附气送去肥料生产。
在一些实施例中，活性炭、分子筛和改性吸附剂均是采用绝干氮气和氨气体积分数为2％～10％的含氨氮气的混合气进行脱附再生的；脱附温度大于100℃，脱附压力不大于80KPaA；绝干氮气形成的脱附气被送至步骤(4)的浓溶液中；由含氨氮气的混合气形成的脱附气送去肥料生产的尾洗工段。
在一些实施例中，改性吸附剂是被有机胺表面改性的多孔氧化铝、被有机胺表面改性的二氧化硅或被有机胺表面改性的多孔高分子聚合物。
在一些实施例中，步骤(9)中低温精馏包括一段精馏和二段精馏；一段精馏先脱低沸点杂质，塔顶压力为0.95～1.15MPaA、温度为-56℃～-51℃，塔釜压力为1.0～1.2MPaA、温度为-51℃～-47℃；二段精馏再脱高沸点杂质，塔顶压力为0.85～1.05MPaA、温度为-60℃～-55℃，塔釜压力为0.9～1.1MPaA、温度为-55℃～-50℃。
实施例1
一种分级利用磷矿石中氟、硅元素的方法，具体包括以下步骤。
(1)酸化：磷矿与硫酸按半水-二水法反应，获得38％P2O5的肥料磷酸，再将其浓缩至55％P2O5。其浓缩技术为现有技术，即采用真空蒸发浓缩。浓缩过程中产生的含氟二次蒸汽和酸化产生的尾气一起送至步骤(2)吸收。
(2)吸收：用清水吸收酸化时产生的尾气，通过在40℃下三级逆流吸收获得质量分数15％的氟硅酸溶液，氟回收率96％。吸收后的尾气送去与纯碱溶液反应，得少量氟硅酸钠。
本实施例采用的三级逆流吸收是指采用外降温强制循环三级逆流真空吸收。外降温强制循环三级逆流真空吸收是指采用蒸发三效逆流强制循环生产装置进行真空吸收，级间采用逆流，以获得较高浓度的溶液；级内采用并流，以减小流体阻力；且每一级吸收均采用上段喷雾、下段填料的并流接触形式，可实现迅速传质并较少雾沫夹带。外降温则是指循环吸收液经过换热器降温后再与气体接触，低温有利于气体溶于液体中。设置条件为喷雾的雾滴粒径100～300μm，每级循环液温度不高于60℃。参见图2所示的含氟气体吸收工艺流程图，包括三个并排放置的吸收塔(T-1、T-2、T-3)，含氟二次蒸汽依次通过T-1、T-2、T-3被吸收后作为尾气，在风机C-1带动下排放。循环液则依 次通过T-3、T-2、T-1，与含氟二次蒸汽逆流，来进行吸收。吸收塔内，上方为空置的喷雾区，下方为填料区，循环液进入吸收塔后通过塔内喷雾装置形成喷雾，然后落到填料区凝成液体，实现与含氟二次蒸汽的充分接触吸收，吸收液通过缓冲槽V、离心泵P后，经冷却器H冷却，冷却后的吸收液可以进入对应的吸收塔再吸收，也可以进入下一级吸收塔吸收。以此浓缩吸收液，故吸收液的浓度可相对偏低，从而更彻底的吸收酸化过程中气相里的氟、硅，也因此，本发明氟回收率极高。以下实施例采用相同的吸收方式，因此不再赘述。
(3)渗透增浓：采用正渗透法，用55％P2O5磷酸做驱动液，逆流渗透，将氟硅酸溶液从质量分数15％浓缩到45％，产出的稀磷酸返回酸化步骤。关于正渗透法的更多内容，请参见前文的相关描述。
(4)提浓、过滤：向45％的氟硅酸溶液中添加占其体积1/50的阳离子萃取剂(75％V P507+25％V煤油)，该混合物与本装置的精馏、气态脱附产生的含杂四氟化硅气在微乳反应器内充分接触，然后，静置澄清20分钟，氟硅酸溶液提浓到质量分数50％，同时产生白炭黑，去过滤。
(5)萃取：1份体积的50％的氟硅酸溶液被0.5份体积的阳离子萃取剂(75％V P507+25％V煤油)萃取，然后，1份体积的萃余液再被0.5份体积的阴离子萃取剂(75％V十二烷基二甲基叔铵+25％V煤油)萃取，得初步净化的氟硅酸溶液。阳离子萃取相萃取后的负载相经水洗涤和5％稀硫酸再生后循环使用，其中，阳离子萃取相萃取后的负载相与水的体积比为10:1，洗涤后的负载相与5％稀硫酸的体积比为10:1。所述阴离子萃取相萃取后的负载相经水洗涤和2％氨水再生后循环使用，其中，阴离子萃取相萃取后的负载相与水的体积比为10:1，洗涤后的负载相与2％氨水的体积比为10:1。
(6)液态吸附：初步净化的氟硅酸溶液依次被活性炭、阳离子树脂和阴离子树脂深度除杂后，得精制的氟硅酸溶液。再生时，先用脱盐水冲洗活性炭、阳离子树脂和阴离子树脂，洗水返回酸化尾气的吸收工序。再用5％质量分数的氢氧化钠溶液清洗活性炭，用5％质量分数的氨水清洗阴离子树脂，然后用脱盐水漂洗活性炭和阴离子树脂，产生的废水送磷肥生产线的尾气吸收。用5％质量分数的硫酸溶液清洗阳离子树脂，然后用脱盐水漂洗，产生的废水送去酸化工序。其中，脱附温度设为60℃。
(7)脱水：用98％的硫酸与精制的氟硅酸溶液在微乳反应器内通过两级逆流接触完成脱水，得粗四氟化硅气体和含氟化氢的硫酸溶液。该溶液被汽提脱氟后变成废硫酸，送去酸化磷矿。汽提的气相经精馏后，获得无水氟化氢。
(8)通过气态吸附除杂：粗四氟化硅气体依次被活性炭、分子筛和被有机胺表面改性的多孔氧化铝深度除杂，得精四氟化硅气体。
其中，活性炭和分子筛采用绝干氮气脱附再生，先在温度100℃、压力0.2MPaA下脱附，脱附气送至所述步骤(4)中用于浓溶液提浓；再在温度200℃，压力0.3MPaA下脱附，脱附气送去肥料生产。活性炭、分子筛和改性吸附剂均是采用绝干氮气和氨气体积分数为2％的含氨氮气的混合气进行脱附再生的；脱附温度105℃，脱附压力80KPaA；绝干氮气形成的脱附气被送至步骤(4)的浓溶液中；由含氨氮气的混合气体形成的脱附气送去肥料生产的尾洗工段。
(9)低温精馏：精四氟化硅气体经二级精馏后，得纯度不低于99.99％的高纯四氟化硅。含杂质的SiF4气体被送至氟硅酸溶液的提浓过滤步骤。
其中，一段精馏先脱低沸点杂质，塔顶压力为0.95MPaA、温度为-56℃，塔釜压力为1.0MPaA、温度为-51℃。二段精馏再脱高沸点杂质，塔顶压力为0.85MPaA、温度为-60℃，塔釜压力为0.9MPaA、温度为-55℃。
实施例2
一种分级利用磷矿石中氟、硅元素的方法，具体包括以下步骤。
(1)酸化：磷矿与硫酸按二水法反应，获得23％P2O5的肥料磷酸，再将其浓缩至55％P2O5。其浓缩技术为现有技术，即采用真空蒸发浓缩。浓缩过程中产生的含氟二次蒸汽和酸化产生的尾气一起送至步骤(2)吸收。
(2)吸收：用清水吸收酸化时产生的尾气，通过在42℃下三级逆流吸收获得质量分数18％的氟硅酸溶液，氟回收率90％。吸收后的尾气送去与NaHCO3溶液反应，得少量氟硅酸钠。关于三级逆流吸的更多内容，请参见上文的相关描述。
(3)渗透增浓：采用正渗透法，用饱和磷酸一铵溶液做驱动液，逆流渗透，将氟硅酸溶液从质量分数18％浓缩到47％，产出的稀磷铵返回磷肥生产线。关于正渗透法的更多内容，请参见前文的相关描述。
(4)提浓过滤：向47％的氟硅酸溶液中添加占其体积1/100的阳离子萃取剂(75％V P204+25％V正庚烷)，该混合物与本装置的精馏、气态脱附产生的含杂四氟化硅气在微乳反应器内充分接触，然后，静置澄清20分钟，氟硅酸溶液提浓到质量分数52％，同时产生白炭黑，去过滤。
(5)萃取：1份体积的52％的氟硅酸溶液被1份体积的阳离子萃取剂(75％V P204+25％V正庚烷)萃取，然后，1份体积的萃余液再被1份体积的阴离子萃取剂(75％V  N-235+25％V正庚烷)萃取，得初步净化的氟硅酸溶液。阳离子萃取相萃取后的负载相经水洗涤和15％稀硫酸再生后循环使用，其中，阳离子萃取相萃取后的负载相与水的体积比为20:1，洗涤后的负载相与15％稀硫酸的体积比为20:1；所述阴离子萃取相萃取后的负载相经水洗涤和12％氨水再生后循环使用，其中，阴离子萃取相萃取后的负载相与水的体积比为20:1，洗涤后的负载相与10％氨水的体积比为20:1。
(6)液态吸附：初步净化的氟硅酸溶液依次被活性炭、阳离子树脂和阴离子树脂深度除杂后，得精制的氟硅酸溶液。再生时，先用脱盐水冲洗活性炭、阳离子树脂和阴离子树脂，洗水返回酸化尾气的吸收工序。再用10％质量分数的氢氧化钠溶液清洗活性炭，用10％质量分数的氨水清洗阴离子树脂，然后用脱盐水漂洗活性炭和阴离子树脂，产生的废水送磷肥生产线的尾气吸收。用20％质量分数的硫酸溶液清洗阳离子树脂，然后用脱盐水漂洗，产生的废水送去酸化工序。其中，脱附温度设为70℃。
(7)脱水：用101％的三氧化硫溶液与精制的氟硅酸溶液在微乳反应器内通过两级逆流接触完成脱水，得粗四氟化硅气体和含氟化氢的硫酸溶液。该溶液被汽提脱氟后变成废硫酸，送去酸化磷矿。汽提的气相经精馏后，获得无水氟化氢。
(8)通过气态吸附除杂：粗四氟化硅气体依次被活性炭、分子筛和被有机胺表面改性的多孔高分子聚合物深度除杂，得精四氟化硅气体。
其中，活性炭和分子筛采用绝干氮气脱附再生，先在温度120℃、压力0.2MPaA下脱附，脱附气送至所述步骤(4)中用于浓溶液提浓；再在温度220℃，压力0.4MPaA下脱附，脱附气送去肥料生产。活性炭、分子筛和改性吸附剂均是采用绝干氮气和氨气体积分数为5％的含氨氮气的混合气进行脱附再生的；脱附温度110℃，脱附压力75KPaA；绝干氮气形成的脱附气被送至步骤(4)的浓溶液中；由含氨氮气的混合气形成的脱附气送去肥料生产的尾洗工段。
(9)低温精馏：精四氟化硅气体经二级精馏后，得纯度不低于99.99％的高纯四氟化硅。含杂质的SiF4气体被送至氟硅酸溶液的提浓、过滤步骤。
其中，一段精馏先脱低沸点杂质，塔顶压力为1.00MPaA、温度为-55℃，塔釜压力为1.0MPaA、温度为-50℃。二段精馏再脱高沸点杂质，塔顶压力为1.00MPaA、温度为-58℃，塔釜压力为1.00MPaA、温度为-54℃。
实施例3
一种分级利用磷矿石中氟、硅元素的方法，具体包括以下步骤。
(1)酸化：磷矿与硫酸按生产普钙反应，并向料浆中通入140℃的过热蒸汽汽 提氟硅酸。该过程产生的含氟二次蒸汽酸化产生的尾气一起送至步骤(2)吸收。
(2)吸收：用清水吸收酸化时产生的尾气，通过在40℃下三级逆流吸收获得质量分数25％的氟硅酸溶液，氟回收率78％。吸收后的尾气送去与KOH溶液反应，得少量氟硅酸钾。关于三级逆流吸的更多内容，请参见上文的相关描述。
(3)渗透增浓：采用正渗透法，用饱和磷酸一铵溶液做驱动液，逆流渗透，将氟硅酸溶液从质量分数25％浓缩到54％，产出的稀磷铵返回磷肥生产线。关于正渗透法的更多内容，请参见前文的相关描述。
(4)提浓、过滤：向54％的氟硅酸溶液中添加占其体积1/150的阳离子萃取剂(75％Vβ萘磺酸+25％V正庚烷)，该混合物与本装置的精馏、气态脱附产生的含杂四氟化硅气在微乳反应器内充分接触，然后，静置澄清20分钟，氟硅酸溶液提浓到质量分数60％，同时产生白炭黑，去过滤。
(5)萃取：1份体积的60％的氟硅酸溶液被3份体积的阳离子萃取剂(75％Vβ萘磺酸+25％V正庚烷)萃取，然后，1份体积的萃余液再被3份体积的阴离子萃取剂(75％V N-235+25％V正庚烷)萃取，得初步净化的氟硅酸溶液。阳离子萃取相萃取后的负载相经水洗涤和30％稀硫酸再生后循环使用，其中，阳离子萃取相萃取后的负载相与水的体积比为30:1，洗后的负载相与30％稀硫酸的体积比为30:1；所述阴离子萃取相萃取后的负载相经水洗涤和20％氨水再生后循环使用，其中，阴离子萃取相萃取后的负载相与水的体积比为30:1，洗后的负载相与20％氨水的体积比为30:1。
(6)液态吸附：初步净化的氟硅酸溶液依次被活性炭、阳离子树脂和阴离子树脂深度除杂后，得精制的氟硅酸溶液。再生时，先用脱盐水冲洗活性炭、阳离子树脂和阴离子树脂，洗水返回酸化尾气的吸收工序。再用5％质量分数的氢氧化钠溶液清洗活性炭，用20％质量分数的氨水清洗阴离子树脂，然后用脱盐水漂洗活性炭和阴离子树脂，产生的废水送磷肥生产线的尾气吸收。用18％质量分数的硫酸溶液清洗阳离子树脂，然后用脱盐水漂洗，产生的废水送去酸化工序。其中，脱附温度设为70℃。
(7)脱水：用93％的硫酸与精制的氟硅酸溶液在微乳反应器内通过两级逆流接触完成脱水，得粗四氟化硅气体和含氟化氢的硫酸溶液。该溶液被汽提脱氟后变成废硫酸，送去酸化磷矿。汽提的气相经精馏后，获得无水氟化氢。
(8)通过气态吸附除杂：粗四氟化硅气体依次被活性炭、分子筛和被有机胺表面改性的二氧化硅深度除杂，得精四氟化硅气体。
其中，活性炭和分子筛采用绝干氮气脱附再生，先在温度140℃、压力0.25MPaA 下脱附，脱附气送至所述步骤(4)中用于浓溶液提浓；再在温度240℃，压力0.4MPaA下脱附，脱附气送去肥料生产。活性炭、分子筛和改性吸附剂均是采用绝干氮气和氨气体积分数为8％的含氨氮气的混合气进行脱附再生的；脱附温度114℃，脱附压力75KPaA；绝干氮气形成的脱附气被送至步骤(4)的浓溶液中；由含氨氮气的混合气形成的脱附气送去肥料生产的尾洗工段。
(9)低温精馏：精四氟化硅气体经二级精馏后，得纯度不低于99.999％的高纯四氟化硅。含杂质的SiF4气体被送至氟硅酸溶液的提浓过滤步骤。
其中，一段精馏先脱低沸点杂质，塔顶压力为1.10MPaA、温度为-52℃，塔釜压力为1.1MPaA、温度为-48℃。二段精馏再脱高沸点杂质，塔顶压力为1.05MPaA、温度为-56℃，塔釜压力为1.00MPaA、温度为-52℃。
实施例4
一种分级利用磷矿石中氟、硅元素的方法，具体包括以下步骤。
(1)酸化：磷矿与磷酸按生产重钙反应，并向料浆中通入140℃的过热蒸汽汽提氟硅酸。该过程产生的含氟二次蒸汽酸化产生的尾气一起送至步骤(2)吸收。
(2)吸收：用清水吸收酸化时产生的尾气，通过在45℃下三级逆流吸收获得质量分数20％的氟硅酸溶液，氟回收率88％。吸收后的尾气送去与纯碱溶液反应，得少量氟硅酸钠。关于三级逆流吸的更多内容，请参见上文的相关描述。
(3)渗透增浓：采用正渗透法，用饱和磷酸一铵溶液做驱动液，逆流渗透，将氟硅酸溶液从质量分数20％浓缩到50％，产出的稀磷铵返回磷肥生产线。
(4)提浓、过滤：向50％的氟硅酸溶液中添加占其体积1/200的阳离子萃取剂(80％V P204+20％V煤油)，该混合物与本装置的精馏、气态脱附产生的含杂四氟化硅气在微乳反应器内充分接触，然后，静置澄清20分钟，氟硅酸溶液提浓到质量分数55％，同时产生白炭黑，去过滤。
(5)萃取：1份体积的55％的氟硅酸溶液被6份体积的阳离子萃取剂(80％V P204+20％V煤油)萃取，然后，1份体积的萃余液再被6份体积的阴离子萃取剂(80％V N-235+20％V正庚烷)萃取，得初步净化的氟硅酸溶液。阳离子萃取相萃取后的负载相经水洗涤和40％稀硫酸再生后循环使用，其中，阳离子萃取相萃取后的负载相与水的体积比为40:1，洗后的负载相与40％稀硫酸的体积比为40:1；所述阴离子萃取相萃取后的负载相经水洗涤和25％氨水再生后循环使用，其中，阴离子萃取相萃取后的负载相与水的体积比为40:1，洗后的负载相与25％氨水的体积比为40:1。
(6)液态吸附：初步净化的氟硅酸溶液依次被活性炭、阳离子树脂和阴离子树脂深度除杂后，得精制的氟硅酸溶液。再生时，先用脱盐水冲洗活性炭、阳离子树脂和阴离子树脂，洗水返回酸化尾气的吸收工序。再用5％质量分数的氢氧化钠溶液清洗活性炭，用25％质量分数的氨水清洗阴离子树脂，然后用脱盐水漂洗活性炭和阴离子树脂，产生的废水送磷肥生产线的尾气吸收。用15％质量分数的硫酸溶液清洗阳离子树脂，然后用脱盐水漂洗，产生的废水送去酸化工序。其中，脱附温度设为80℃。
(7)脱水：用98.3％的硫酸与精制的氟硅酸溶液在微乳反应器内通过两级逆流接触完成脱水，得粗四氟化硅气体和含氟化氢的硫酸溶液。该溶液被汽提脱氟后变成废硫酸，送去酸化磷矿。汽提的气相经精馏后，获得无水氟化氢。
(8)通过气态吸附除杂：粗四氟化硅气体依次被活性炭、分子筛和有机胺表面改性的多孔氧化铝深度除杂，得精四氟化硅气体。
其中，活性炭和分子筛采用绝干氮气脱附再生，先在温度150℃、压力0.3MPaA下脱附，脱附气送至所述步骤(4)中用于浓溶液提浓；再在温度250℃，压力0.5MPaA下脱附，脱附气送去肥料生产。活性炭、分子筛和改性吸附剂均是采用绝干氮气和氨气体积分数为10％的含氨氮气的混合气进行脱附再生的；脱附温度110℃，脱附压力80KPaA；绝干氮气形成的脱附气被送至步骤(4)的浓溶液中；由含氨氮气的混合气形成的脱附气送去肥料生产的尾洗工段。
(9)低温精馏：精四氟化硅气体经二级精馏后，得纯度不低于99.999％的高纯四氟化硅。含杂质的SiF4气体被送至氟硅酸溶液的提浓、过滤步骤。
其中，一段精馏先脱低沸点杂质，塔顶压力为1.15MPaA、温度为-51℃，塔釜压力为1.0～1.2MPaA、温度为-47℃。二段精馏再脱高沸点杂质，塔顶压力为1.05MPaA、温度为-55℃，塔釜压力为1.10MPaA、温度为-50℃。
上文已对基本概念做了描述，显然，对于本领域技术人员来说，上述详细披露仅仅作为示例，而并不构成对本申请的限定。虽然此处并没有明确说明，本领域技术人员可能会对本申请进行各种修改、改进和修正。该类修改、改进和修正在本申请中被建议，所以该类修改、改进、修正仍属于本申请示范实施例的精神和范围。
同时，本申请使用了特定词语来描述本申请的实施例。如“一个实施例”、“一实施例”、和/或“一些实施例”意指与本申请至少一个实施例相关的某一特征、结构或特点。因此，应强调并注意的是，本说明书中在不同位置两次或多次提及的“一实施例”或“一个实施例”或“一个替代性实施例”并不一定是指同一实施例。此外，本申请的 一个或多个实施例中的某些特征、结构或特点可以进行适当的组合。
此外，除非权利要求中明确说明，本申请所述处理元素和序列的顺序、数字字母的使用、或其他名称的使用，并非用于限定本申请流程和方法的顺序。尽管上述披露中通过各种示例讨论了一些目前认为有用的发明实施例，但应当理解的是，该类细节仅起到说明的目的，附加的权利要求并不仅限于披露的实施例，相反，权利要求旨在覆盖所有符合本申请实施例实质和范围的修正和等价组合。
同理，应当注意的是，为了简化本申请披露的表述，从而帮助对一个或多个发明实施例的理解，前文对本申请实施例的描述中，有时会将多种特征归并至一个实施例、附图或对其的描述中。但是，这种披露方法并不意味着本申请对象所需要的特征比权利要求中提及的特征多。实际上，实施例的特征要少于上述披露的单个实施例的全部特征。
一些实施例中使用了描述成分、属性数量的数字，应当理解的是，此类用于实施例描述的数字，在一些示例中使用了修饰词“大约”、“近似”或“大体上”来修饰。除非另外说明，“大约”、“近似”或“大体上”表明所述数字允许有±20％的变化。相应地，在一些实施例中，说明书和权利要求中使用的数值参数均为近似值，该近似值根据个别实施例所需特点可以发生改变。在一些实施例中，数值参数应考虑规定的有效数位并采用一般位数保留的方法。尽管本申请一些实施例中用于确认其范围广度的数值域和参数为近似值，在具体实施例中，此类数值的设定在可行范围内尽可能精确。
针对本申请引用的每个专利、专利申请、专利申请公开物和其他材料，如文章、书籍、说明书、出版物、文档等，特此将其全部内容并入本申请作为参考。与本申请内容不一致或产生冲突的申请历史文件除外，对本申请权利要求最广范围有限制的文件(当前或之后附加于本申请中的)也除外。需要说明的是，如果本申请附属材料中的描述、定义、和/或术语的使用与本申请所述内容有不一致或冲突的地方，以本申请的描述、定义和/或术语的使用为准。
最后，应当理解的是，本申请中所述实施例仅用以说明本申请实施例的原则。其他的变形也可能属于本申请的范围。因此，作为示例而非限制，本申请实施例的替代配置可视为与本申请的教导一致。相应地，本申请的实施例不仅限于本申请明确介绍和描述的实施例。

Claims (19)

  1. 一种分级利用磷矿石中氟、硅资源的方法，其特征在于，包括以下步骤：
    步骤(1)，酸化：将硫酸或磷酸与磷矿混合反应，生成稀磷酸或/和磷肥，同时产生含氟、硅的尾气；
    步骤(2)，吸收：用水吸收所述尾气，得到含氟、硅的酸性溶液；
    步骤(3)，渗透增浓：利用驱动液与所述酸性溶液进行渗透操作，驱动液吸收酸性溶液中的部分溶剂，得到稀溶液；所述酸性溶液浓度增加，得到浓溶液；
    其中，所述渗透操作是正渗透，所述驱动液为磷酸盐溶液或磷酸溶液，所述稀溶液包括稀磷酸盐溶液或稀磷酸溶液；
    步骤(4)，提浓过滤：向所述浓溶液中通入氟化硅气体进行提浓操作，以继续提高所述浓溶液的浓度；然后过滤分离，得到SiO2固体、含氟溶液和废气；
    步骤(5)，萃取：在所述含氟溶液中加入萃取相，并充分混合萃取，分相得到负载相和萃余液；
    步骤(6)，液态吸附：吸附脱除所述萃余液里的杂质，得到精制溶液；
    步骤(7)，脱水：在所述精制溶液中加入脱水剂并充分混合，得到粗SiF4气体和HF-硫酸溶液，将所述HF-硫酸溶液经汽提、精馏分离产出纯度不低于99％的无水氟化氢和副产物废硫酸；
    步骤(8)，除杂：通过气态吸附吸附所述粗SiF4气体中的杂质，得到除杂气；
    步骤(9)，低温精馏：对除杂气进行低温精馏，深度脱除低沸点、高沸点的杂质，得到杂质气，及纯度不低于99％的SiF4。
  2. 根据权利要求1所述的分级利用磷矿石中氟、硅资源的方法，其特征在于，所述步骤(3)中得到的稀磷酸溶液、所述步骤(7)中得到的废硫酸均送入所述步骤(1)中与磷矿混合；所述步骤(4)得到的废气送入所述步骤(2)中与尾气一起被吸收；所述步骤(9)得到的所述杂质气作为SiF4气体通入所述步骤(4)中的浓溶液中。
  3. 根据权利要求1所述的分级利用磷矿石中氟、硅资源的方法，其特征在于，在所述步骤(1)中，磷矿与硫酸按生产普钙反应，向料浆中通入不低于140℃的过热蒸汽汽提氟硅酸，得到产品普钙和含氟二次蒸汽，所述含氟二次蒸汽与所述步骤(1)产生 的所述尾气一起送至步骤(2)吸收。
  4. 根据权利要求1所述的分级利用磷矿石中氟、硅资源的方法，其特征在于，所述步骤(1)中的硫酸或磷酸与磷矿混合后得到稀磷酸，将所述稀磷酸浓缩，得到含氟二次蒸汽和P2O5质量分数不低于54％的肥料磷酸；所述含氟二次蒸汽与步骤(1)产生的所述尾气一起送至所述步骤(2)吸收。
  5. 根据权利要求1所述的分级利用磷矿石中氟、硅资源的方法，其特征在于，所述步骤(2)采用外降温强制循环三级逆流真空吸收，且每一级吸收均采用上段喷雾、下段填料的并流接触形式，喷雾的雾滴粒径为100～300μm，每级循环液温度不高于60℃。
  6. 根据权利要求5所述的分级利用磷矿石中氟、硅资源的方法，其特征在于，所述步骤(2)中未被吸收的尾气被送去深度吸收；深度吸收采用的吸收剂包括Na2CO3、NaHCO3或KOH溶液，深度吸收的温度不高于40℃。
  7. 根据权利要求1所述的分级利用磷矿石中氟、硅资源的方法，其特征在于，所述步骤(4)的所述提浓操作是在微乳反应器内进行。
  8. 根据权利要求1所述的分级利用磷矿石中氟、硅资源的方法，其特征在于，所述步骤(4)的所述提浓操作中，所述浓溶液先与表面活性剂充分混合，再与SiF4气体混合；所述表面活性剂与所述浓溶液的体积比为1:200～1:50；其中，所述表面活性剂为阳离子萃取的萃取相。
  9. 根据权利要求1所述的分级利用磷矿石中氟、硅资源的方法，其特征在于，所述步骤(5)中的所述萃取相由萃取剂和稀释剂组成，所述萃取剂的体积分数不大于80％，所述稀释剂是煤油、异丙醚、C6～C14的烃中的一种或几种的混合物。
  10. 根据权利要求9所述的分级利用磷矿石中氟、硅资源的方法，其特征在于，所述步骤(5)的所述萃取包括阳离子萃取和阴离子萃取，且阳离子萃取和阴离子萃取后 的负载相均经洗涤、再生后循环使用。
  11. 根据权利要求10所述的分级利用磷矿石中氟、硅资源的方法，其特征在于，所述阳离子萃取的萃取相与含氟溶液的体积比为0.5:1～6:1，所述阳离子萃取相的萃取剂是有机膦类、磷脂类、羧酸类、磺酸类有机溶剂中的一种或几种的混合物；所述阴离子萃取的萃取相与含氟溶液的体积为0.5:1～6:1，所述阴离子萃取相的萃取剂是有机胺类萃取剂。
  12. 根据权利要求11所述的分级利用磷矿石中氟、硅资源的方法，其特征在于，所述阳离子萃取相萃取后的负载相经水洗涤和5％～40％稀硫酸再生后循环使用，其中，所述阳离子萃取相萃取后的负载相与水的体积比为10:1～40:1，水洗后的负载相与5％～40％稀硫酸的体积比为10:1～40:1；所述阴离子萃取相萃取后的负载相经水洗涤和2％～25％氨水再生后循环使用，其中，所述阴离子萃取相萃取后的负载相与水的体积比为10:1～40:1，水洗后的负载相与2％～25％氨水的体积比为10:1～40:1；两次水洗涤后产生的洗余液返回所述步骤(2)中用于吸收尾气；两次再生后产生的再生废液用于磷矿酸化或肥料生产。
  13. 根据权利要求1所述的分级利用磷矿石中氟、硅资源的方法，其特征在于，所述步骤(6)中的所述液态吸附包括活性炭吸附、阳离子吸附和阴离子吸附，活性炭、阳离子吸附剂和阴离子吸附剂吸附饱和后经脱附再生得以重复使用；其中，脱附再生活性炭时，先用水脱附，再用5％～10％质量分数的氢氧化钠溶液脱附；脱附再生阳离子吸附剂，先用水脱附，再用5％～20％质量分数的硫酸溶液脱附；脱附再生阴离子吸附剂，先用水脱附，再用5％～25％质量分数的氨水脱附；脱附温度为60～80℃；由水脱附形成的脱附液返回所述步骤(2)中吸附所述尾气；氢氧化钠溶液脱附、氨水脱附所形成的脱附液用于肥料生产，硫酸溶液脱附所形成的脱附液用于磷矿酸化。
  14. 根据权利要求1所述的分级利用磷矿石中氟、硅资源的方法，其特征在于，所述步骤(7)中所述精制溶液与脱水剂在微乳反应器内通过两级逆流接触完成脱水；其中，所述步骤(7)中的脱水剂是三氧化硫、发烟硫酸、质量分数大于93％的浓硫酸中 的一种或几种的混合物。
  15. 根据权利要求1所述的分级利用磷矿石中氟、硅资源的方法，其特征在于，所述步骤(8)中的气态吸附包括活性炭吸附、分子筛吸附和改性吸附剂吸附，且活性炭、分子筛和改性吸附剂吸附饱和后经脱附再生得以重复使用。
  16. 根据权利要求15所述的分级利用磷矿石中氟、硅资源的方法，其特征在于，所述活性炭和分子筛采用绝干氮气脱附再生，先在温度100～150℃、压力0.2～0.3MPaA下脱附，脱附气送至所述步骤(4)中用于浓溶液提浓；再在温度200～250℃，压力0.3～0.5MPaA下脱附，脱附气送去肥料生产。
  17. 根据权利要求16所述的分级利用磷矿石中氟、硅资源的方法，其特征在于，所述活性炭、分子筛和改性吸附剂均是采用绝干氮气和氨气体积分数为2％～10％的含氨氮气的混合气进行脱附再生的；脱附温度大于100℃，脱附压力不大于80KPaA；绝干氮气形成的脱附气被送至步骤(4)的浓溶液中；由含氨氮气的混合气形成的脱附气送去肥料生产的尾洗工段。
  18. 根据权利要求17所述的分级利用磷矿石中氟、硅资源的方法，其特征在于，所述改性吸附剂是被有机胺表面改性的多孔氧化铝、被有机胺表面改性的二氧化硅或被有机胺表面改性的多孔高分子聚合物。
  19. 根据权利要求18所述的分级利用磷矿石中氟、硅资源的方法，其特征在于，所述步骤(9)中的所述低温精馏包括一段精馏和二段精馏；所述一段精馏先脱低沸点杂质，塔顶压力为0.95～1.15MPaA、温度为-56℃～-51℃，塔釜压力为1.0～1.2MPaA、温度为-51℃～-47℃；所述二段精馏再脱高沸点杂质，塔顶压力为0.85～1.05MPaA、温度为-60℃～-55℃，塔釜压力为0.9～1.1MPaA、温度为-55℃～-50℃。
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