CN110683514A - Method for purifying and preparing hydrogen fluoride - Google Patents
Method for purifying and preparing hydrogen fluoride Download PDFInfo
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- C01B7/00—Halogens; Halogen acids
- C01B7/19—Fluorine; Hydrogen fluoride
- C01B7/191—Hydrogen fluoride
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Abstract
The invention discloses a hydrogen fluoride purification preparation method, which is characterized in that the generated hydrogen fluoride gas is purified and prepared in the process of preparing ordinary calcium and calcium-rich white fertilizer; the method comprises the following steps: s1 hot drying the white fertilizer; s2 preparing concentrated fluosilicic acid and primary crude hydrogen fluoride; s3, preparing a crude sulfuric acid diluent and secondary crude hydrogen fluoride; s4, preparing newly-prepared sulfuric acid, anhydrous hydrogen fluoride and light component impurity gas; s5, preparing anhydrous hydrogen fluoride and waste gas; recovering the S6 waste gas to generate anhydrous hydrogen fluoride; the invention has the beneficial effects that: the reaction product is purified to prepare the hydrogen fluoride, so that the purity is ensured; preparing high-purity hydrogen fluoride gas by adopting a multistage circulation process; the purification process flow is reduced by adopting a heat flow drying mode; the fluosilicic acid is in countercurrent contact to obtain concentrated fluosilicic acid which is purified to provide purified concentrated fluosilicic acid for the subsequent generation of hydrogen fluoride gas; and the condensation is adopted, so that the reaction speed is accelerated, and impurities with low freezing point and gas impurities with low boiling point can be removed.
Description
Technical Field
The invention relates to the field of hydrogen fluoride preparation, in particular to a hydrogen fluoride purification preparation method.
Background
At present, the feed-grade calcium hydrophosphate is usually prepared by adopting a defluorination and pressure filtration process in China, a large amount of waste residues generated in a defluorination working section are called defluorination residues (also called white fertilizers), a large amount of citrate-soluble phosphorus and fluorine are also contained in the white fertilizers, and the white fertilizers generated in China are mainly dried and recycled as raw materials of crude fertilizers or compound fertilizers, but harmful fluorine cannot be removed, and simultaneously the medium fluorine cannot be converted into hydrogen fluoride for recycling, so that the hydrogen fluoride can be directly used as the crude fertilizers or the compound fertilizers, and the fluorosis of crops can be possibly caused. However, with the improvement of the living standard of people and the enhancement of food safety in the near future, China also limits harmful elements in the fertilizer like Europe and America, and the fluorine content in the fertilizer is also limited inevitably, so that the white fertilizer can be brought out of the way to meet great challenges and threaten the survival of calcium hydrophosphate plants; the phosphogypsum production, the high added value of the white fertilizer and the harmlessness are the living essentials of the vitamin calcium hydrophosphate in the future; especially, in the preparation of feed-grade calcium hydrophosphate, the white fertilizer can generate a large amount of hydrogen fluoride gas which is diffused into the air to pollute the air, and the hydrogen fluoride has strong toxicity and is easy to influence the absorption of human calcium and damage human bones, so the harmless treatment of the hydrogen fluoride gas is emphasized in the preparation process of the white fertilizer.
The invention discloses a method for preparing hydrogen fluoride in the production process of feed-grade calcium hydrophosphate (2016103429319). The method for preparing hydrogen fluoride in the production process of feed-grade calcium hydrophosphate comprises the steps of introducing fluorine-containing tail gas into an ammonia water solution tank, discharging absorption liquid into a sedimentation tank when the pH value is 2.5-3.5, and adding ammonia water into the ammonia water solution tank; evaporating and concentrating the supernatant in the sedimentation tank under reduced pressure to obtain ammonium fluosilicate solid, adding the ammonium fluosilicate solid into concentrated sulfuric acid, leading the generated gas to pass through a condensation tower, wherein the condensed liquid is hydrogen fluoride, and leading the residual tail gas into the ammonia water solution tank for recycling; but ammonia water is adopted to participate in the whole reaction process, a third-party reagent is introduced, and certain impurities are doped in feed-grade calcium hydrophosphate and participate in the reaction to influence the purity of hydrogen fluoride; meanwhile, tail gas is directly used for entering a circulation process, and the circulation frequency of a single circulation process is too high to influence the generated hydrogen fluoride gas because the tail gas does not carry out fractional circulation aiming at various gases contained in the tail gas; therefore, a complete conversion, multi-stage circulation and environmentally friendly method for purifying and preparing hydrogen fluoride is urgently needed.
Disclosure of Invention
The present invention aims to overcome the disadvantages of the prior art and to provide a process for the preparation of hydrogen fluoride which at least achieves the aim of complete conversion, multistage circulation and no environmental pollution.
The purpose of the invention is realized by the following technical scheme:
a hydrogen fluoride purification preparation method is characterized in that the hydrogen fluoride gas generated in the process of preparing ordinary calcium and calcium-rich white fertilizer is purified and prepared; the method comprises the following steps:
s1, drying the white fertilizer by heating, and collecting gas overflowing to a gas phase by adopting a double-shaft reaction mode;
s2, absorbing moisture and hydrogen fluoride by sulfuric acid to obtain primary crude hydrogen fluoride; absorbing the residual gas after absorption by water vapor and concentrating to obtain concentrated fluosilicic acid;
s3, preheating the obtained concentrated fluosilicic acid, and performing concentrated sulfuric acid action in a closed environment to obtain a mixed solution, and distilling the mixed solution to obtain a crude sulfuric acid diluent and secondary crude hydrogen fluoride;
s4, the obtained crude sulfuric acid diluent is purified by steam stripping to obtain fresh sulfuric acid, and the obtained fresh sulfuric acid is returned to the step; pre-purifying the obtained primary and secondary rough hydrogen fluoride to remove high-boiling point impurities to obtain I-grade hydrogen fluoride gas, condensing to obtain I-grade hydrogen fluoride liquid, pre-purifying the I-grade hydrogen fluoride liquid again to obtain II-grade hydrogen fluoride liquid, and drying the II-grade hydrogen fluoride liquid after pressure rectification to obtain anhydrous hydrogen fluoride and light component impurity gas;
s5, cooling the obtained anhydrous hydrogen fluoride by pressure and sulfuric acid to obtain purified anhydrous hydrogen fluoride, and warehousing for storage; absorbing the obtained light component impurity gas by sulfuric acid, then carrying out the steps of S2-S4 again to obtain anhydrous hydrogen fluoride and waste gas, cooling the obtained anhydrous hydrogen fluoride by the pressure and sulfuric acid, and warehousing for storage;
s6, carrying out counter-current contact reaction on the obtained waste gas by fluosilicic acid, separating by using a filter cake to obtain concentrated fluosilicic acid and tail gas, returning the obtained concentrated fluosilicic acid to the steps S3-S5 for further purification and absorption to obtain purified anhydrous hydrogen fluoride, and warehousing for storage; and (4) the tail gas is treated by steps S1-S5, then is washed by water and is discharged into the air, and the washed waste water is used for washing the filter cake, so that the circulating process is completed.
Preferably, in order to make the waste gas containing silicon fluoride fully absorbed in water solution, the fluosilicic acid countercurrent contact reaction is that the waste gas containing silicon fluoride passes through fluosilicic acid to generate water solution reaction:
5SiF4+2H2O→2H2SiF6·SiF4+SiO2；
the silicon dioxide is separated by filtering the filter cake; and separating the generated silicon dioxide through a filter cake to obtain the concentrated fluosilicic acid through purification.
Preferably, in order to further enable the white fertilizer to be sufficiently dried in a hot mode and reduce water vapor to participate in the hydrogen fluoride preparation process, the white fertilizer is dried in a hot mode through air flow, the white fertilizer is dried in a hot mode, the white fertilizer is dried in a fully drying standard, the white fertilizer is limited to be dried in a moisture content of less than 1%, the white fertilizer is dried in a fully drying standard, the water vapor content of gas in the hot drying process is low, and the purification process flow is reduced.
Preferably, in order to further reduce impurities in the crude hydrogen fluoride gas, the preliminary purification is to place the primary and secondary crude hydrogen fluoride gases in a preliminary purification tower, and remove high-boiling impurities by cooling in the tower; the high boiling point impurities are converted from gas phase to liquid phase or solid phase in a cooling mode through cooling treatment in a pre-purification tower, so that gas-liquid or gas-solid separation is realized; thereby realizing the removal of high boiling point impurities.
Preferably, in order to further return the newly prepared sulfuric acid to the reaction system and embody a circulation process, the newly prepared sulfuric acid is sulfuric acid obtained by stripping the crude sulfuric acid diluent to remove hydrogen fluoride; the mass fraction of the fresh sulfuric acid is 70-75%; further, the sulfuric acid reaches the level of industrial-grade sulfuric acid by adopting a stripping mode, and then the sulfuric acid is returned to a reaction system, so that a circulating process is embodied.
Preferably, in order to further fully condense the hydrogen fluoride gas, two cascade condensers are adopted for condensation, the temperature of a condensing agent is set to be 10-15 ℃, and the low-temperature condensing agent is adopted to rapidly liquefy the I-grade hydrogen fluoride gas, so that the reaction speed is increased, and meanwhile, impurities with low freezing points and gas impurities with low boiling points can be removed.
Preferably, in order to further limit the composition of the mixed liquid entering the distillation process, the mixed liquid comprises sulfuric acid, water and hydrogen fluoride, and further, the crude sulfuric acid diluent, the primary crude hydrogen fluoride and the secondary crude hydrogen fluoride are separated by distillation, so that the subsequent separation of each part is facilitated.
Preferably, in order to further enable the gas generated in the system to sufficiently participate in the reaction, the light component impurity gas comprises sulfur dioxide and silicon fluoride, and the light component impurity gas is defined to further explain the reason for the light component impurity gas to participate in the reaction system, so that the hydrogen fluoride purification preparation process is more complete.
The invention has the beneficial effects that:
1. in the process of preparing ordinary calcium and calcium-rich by adopting the white fertilizer, the hydrogen fluoride is prepared by purifying the reaction product in the reaction system without introducing other reagent elements, so that the purity of the prepared hydrogen fluoride is ensured, and meanwhile, the high-purity hydrogen fluoride gas can be prepared by adopting a multistage circulation process, and the silicon element in the white fertilizer is completely removed, so that the method is harmless to the environment.
2. By adopting a heat flow drying mode, the moisture of the white fertilizer is ensured to be less than 1 percent, the white fertilizer is fully dried, the moisture content in the gas in the heat drying process is further ensured to be low, and the purification process flow is reduced.
3. The waste gas containing silicon fluoride is subjected to fluosilicic acid countercurrent contact to generate water-soluble reaction, and the generated silicon dioxide is separated out through a filter cake to obtain concentrated fluosilicic acid through purification, so that purified concentrated fluosilicic acid is provided for the subsequent generation of hydrogen fluoride gas.
4. Two cascade condensers are adopted, and the temperature of a condensing agent is set to be 10-15 ℃ as a condensing mode, so that the reaction speed is accelerated, and impurities with low freezing point and gas impurities with low boiling point can be removed.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Detailed Description
The technical solutions of the present invention are further described in detail below with reference to the accompanying drawings, but the scope of the present invention is not limited to the following.
Example 1
As shown in fig. 1, a method for purifying and preparing hydrogen fluoride, which is to purify and prepare hydrogen fluoride gas generated in the process of preparing common calcium from white fertilizer and enriching calcium; the method comprises the following steps:
s1, drying the white fertilizer by heating, and collecting gas overflowing to a gas phase by adopting a double-shaft reaction mode; in order to further enable the white fertilizer to be fully dried by heating and reduce the participation of water vapor in the hydrogen fluoride preparation process, the white fertilizer is dried by adopting airflow, the moisture content of the white fertilizer is less than 1 percent as the full drying standard, and the moisture content of the white fertilizer is less than 1 percent as the full drying standard, so that the low water vapor content in the gas in the drying process is ensured, and the purification process flow is reduced;
s2, absorbing moisture and hydrogen fluoride by sulfuric acid to obtain primary crude hydrogen fluoride; absorbing the residual gas after absorption by water vapor and concentrating to obtain concentrated fluosilicic acid;
s3, preheating the obtained concentrated fluosilicic acid, and performing concentrated sulfuric acid action in a closed environment to obtain a mixed solution, and distilling the mixed solution to obtain a crude sulfuric acid diluent and secondary crude hydrogen fluoride;
s4, the obtained crude sulfuric acid diluent is purified by steam stripping to obtain fresh sulfuric acid, and the obtained fresh sulfuric acid is returned to the step; pre-purifying the obtained primary and secondary rough hydrogen fluoride to remove high-boiling point impurities to obtain I-grade hydrogen fluoride gas, condensing to obtain I-grade hydrogen fluoride liquid, pre-purifying the I-grade hydrogen fluoride liquid again to obtain II-grade hydrogen fluoride liquid, and drying the II-grade hydrogen fluoride liquid after pressure rectification to obtain anhydrous hydrogen fluoride and light component impurity gas; in order to further reduce impurities in the crude hydrogen fluoride gas, the pre-purification is to place the crude hydrogen fluoride gas in a pre-purification tower, and remove high-boiling-point impurities by cooling in the tower; the high boiling point impurities are converted from gas phase to liquid phase or solid phase in a cooling mode through cooling treatment in a pre-purification tower, so that gas-liquid or gas-solid separation is realized; thereby realizing the removal of high boiling point impurities; in order to further return the newly prepared sulfuric acid to the reaction system and embody a circulating process, the newly prepared sulfuric acid is sulfuric acid obtained by stripping the crude sulfuric acid diluent to remove hydrogen fluoride; the mass fraction of the fresh sulfuric acid is 70-75%; further, the sulfuric acid reaches the level of industrial-grade sulfuric acid by adopting a stripping mode, and then the sulfuric acid is returned to a reaction system, so that a circulating process is embodied; in order to further fully condense the hydrogen fluoride gas, two cascade condensers are adopted for condensation, the temperature of a condensing agent is set to be 10 ℃, and the low-temperature condensing agent is adopted to rapidly liquefy the I-grade hydrogen fluoride gas, so that the reaction speed is increased and impurities with low condensation point and gas impurities with low boiling point can be removed;
s5, cooling the obtained anhydrous hydrogen fluoride by pressure and sulfuric acid to obtain purified anhydrous hydrogen fluoride, and warehousing for storage; absorbing the obtained light component impurity gas by sulfuric acid, then carrying out the steps of S2-S4 again to obtain anhydrous hydrogen fluoride and waste gas, cooling the obtained anhydrous hydrogen fluoride by the pressure and sulfuric acid, and warehousing for storage;
s6, carrying out counter-current contact reaction on the obtained waste gas by fluosilicic acid, separating by using a filter cake to obtain concentrated fluosilicic acid and tail gas, returning the obtained concentrated fluosilicic acid to the steps S3-S5 for further purification and absorption to obtain purified anhydrous hydrogen fluoride, and warehousing for storage; the tail gas is treated by steps S1-S5, then is washed by water and then is discharged into the air, and the washed waste water washes the filter cake to complete the cycle process; the fluosilicic acid countercurrent contact reaction is that waste gas containing silicon fluoride passes through fluosilicic acid to generate a water-soluble reaction:
5SiF4+2H2O→2H2SiF6·SiF4+SiO2；
the silicon dioxide is separated by filtering the filter cake; and separating the generated silicon dioxide through a filter cake of the molecular sieve to obtain the concentrated fluosilicic acid through purification.
Example 2
As shown in fig. 1, a method for purifying and preparing hydrogen fluoride, which is to purify and prepare hydrogen fluoride gas generated in the process of preparing common calcium from white fertilizer and enriching calcium; the method comprises the following steps:
s1, drying the white fertilizer by heating, and collecting gas overflowing to a gas phase by adopting a double-shaft reaction mode; in order to further enable the white fertilizer to be fully dried by heating and reduce the participation of water vapor in the hydrogen fluoride preparation process, the white fertilizer is dried by adopting airflow, the moisture content of the white fertilizer is less than 1 percent as the full drying standard, and the moisture content of the white fertilizer is less than 1 percent as the full drying standard, so that the low water vapor content in the gas in the drying process is ensured, and the purification process flow is reduced;
s2, absorbing moisture and hydrogen fluoride by sulfuric acid to obtain primary crude hydrogen fluoride; absorbing the residual gas after absorption by water vapor and concentrating to obtain concentrated fluosilicic acid;
s3, preheating the obtained concentrated fluosilicic acid, and performing concentrated sulfuric acid action in a closed environment to obtain a mixed solution, and distilling the mixed solution to obtain a crude sulfuric acid diluent and secondary crude hydrogen fluoride;
s4, the obtained crude sulfuric acid diluent is purified by steam stripping to obtain fresh sulfuric acid, and the obtained fresh sulfuric acid is returned to the step; pre-purifying the obtained primary and secondary rough hydrogen fluoride to remove high-boiling point impurities to obtain I-grade hydrogen fluoride gas, condensing to obtain I-grade hydrogen fluoride liquid, pre-purifying the I-grade hydrogen fluoride liquid again to obtain II-grade hydrogen fluoride liquid, and drying the II-grade hydrogen fluoride liquid after pressure rectification to obtain anhydrous hydrogen fluoride and light component impurity gas; in order to further reduce impurities in the crude hydrogen fluoride gas, the preliminary purification is to place the primary and secondary crude hydrogen fluoride gases in a preliminary purification tower, and remove high-boiling-point impurities by cooling in the tower; the high boiling point impurities are converted from gas phase to liquid phase or solid phase in a cooling mode through cooling treatment in a pre-purification tower, so that gas-liquid or gas-solid separation is realized; thereby realizing the removal of high boiling point impurities; in order to further return the newly prepared sulfuric acid to the reaction system and embody a circulating process, the newly prepared sulfuric acid is sulfuric acid obtained by stripping the crude sulfuric acid diluent to remove hydrogen fluoride; the mass fraction of the fresh sulfuric acid is 70-75%; further, the sulfuric acid reaches the level of industrial-grade sulfuric acid by adopting a stripping mode, and then the sulfuric acid is returned to a reaction system, so that a circulating process is embodied; in order to further fully condense the hydrogen fluoride gas, two cascade condensers are adopted for condensation, the temperature of a condensing agent is set to be 15 ℃, and the low-temperature condensing agent is adopted to rapidly liquefy the I-grade hydrogen fluoride gas, so that the reaction speed is increased and impurities with low condensation point and gas impurities with low boiling point can be removed;
s5, cooling the obtained anhydrous hydrogen fluoride by pressure and sulfuric acid to obtain purified anhydrous hydrogen fluoride, and warehousing for storage; absorbing the obtained light component impurity gas by sulfuric acid, then carrying out the steps of S2-S4 again to obtain anhydrous hydrogen fluoride and waste gas, cooling the obtained anhydrous hydrogen fluoride by the pressure and sulfuric acid, and warehousing for storage;
s6, carrying out counter-current contact reaction on the obtained waste gas by fluosilicic acid, separating by using a filter cake to obtain concentrated fluosilicic acid and tail gas, returning the obtained concentrated fluosilicic acid to the steps S3-S5 for further purification and absorption to obtain purified anhydrous hydrogen fluoride, and warehousing for storage; directly washing the tail gas with water, then discharging the tail gas into air, and washing the filter cake with the washed wastewater to finish a circulating process; the fluosilicic acid countercurrent contact reaction is that waste gas containing silicon fluoride passes through fluosilicic acid to generate a water-soluble reaction:
5SiF4+2H2O→2H2SiF6·SiF4+SiO2；
the silicon dioxide is separated by filtering the filter cake; and separating the generated silicon dioxide through a filter cake to obtain the concentrated fluosilicic acid through purification.
Example 3
As shown in fig. 1, a method for purifying and preparing hydrogen fluoride, which is to purify and prepare hydrogen fluoride gas generated in the process of preparing common calcium from white fertilizer and enriching calcium; the method comprises the following steps:
s1, drying the white fertilizer by heating, and collecting gas overflowing to a gas phase by adopting a double-shaft reaction mode; in order to further enable the white fertilizer to be fully dried in a hot mode and reduce water vapor to participate in the hydrogen fluoride preparation process, the white fertilizer is dried in a hot mode through airflow, the moisture content of the white fertilizer is smaller than 1% as a full drying standard, the moisture content of the white fertilizer is limited to be smaller than 1% as the full drying standard, and therefore it is guaranteed that the water vapor S2 in the gas in the hot drying process absorbs the moisture content and the hydrogen fluoride through sulfuric acid, and primary crude hydrogen fluoride is obtained; absorbing the residual gas after absorption by water vapor and concentrating to obtain concentrated fluosilicic acid;
s3, preheating the obtained concentrated fluosilicic acid, and performing concentrated sulfuric acid action in a closed environment to obtain a mixed solution, and distilling the mixed solution to obtain a crude sulfuric acid diluent and secondary crude hydrogen fluoride;
s4, the obtained crude sulfuric acid diluent is purified by steam stripping to obtain fresh sulfuric acid, and the obtained fresh sulfuric acid is returned to the step; pre-purifying the obtained primary and secondary rough hydrogen fluoride to remove high-boiling point impurities to obtain I-grade hydrogen fluoride gas, condensing to obtain I-grade hydrogen fluoride liquid, pre-purifying the I-grade hydrogen fluoride liquid again to obtain II-grade hydrogen fluoride liquid, and drying the II-grade hydrogen fluoride liquid after pressure rectification to obtain anhydrous hydrogen fluoride and light component impurity gas; in order to further reduce impurities in the crude hydrogen fluoride gas, the preliminary purification is to place the primary and secondary crude hydrogen fluoride gases in a preliminary purification tower, and remove high-boiling-point impurities by cooling in the tower; the high boiling point impurities are converted from gas phase to liquid phase or solid phase in a cooling mode through cooling treatment in a pre-purification tower, so that gas-liquid or gas-solid separation is realized; thereby realizing the removal of high boiling point impurities; in order to further return the newly prepared sulfuric acid to the reaction system and embody a circulating process, the newly prepared sulfuric acid is sulfuric acid obtained by stripping the crude sulfuric acid diluent to remove hydrogen fluoride; the mass fraction of the fresh sulfuric acid is 70-75%; further, the sulfuric acid reaches the level of industrial-grade sulfuric acid by adopting a stripping mode, and then the sulfuric acid is returned to a reaction system, so that a circulating process is embodied; in order to further fully condense the hydrogen fluoride gas, the condensation adopts two cascade condensers, the temperature of a condensing agent is set to be 12 ℃, and the low-temperature condensing agent is adopted to rapidly liquefy the I-grade hydrogen fluoride gas, so that the reaction speed is increased and impurities with low condensation point and gas impurities with low boiling point can be removed;
s5, cooling the obtained anhydrous hydrogen fluoride by pressure and sulfuric acid to obtain purified anhydrous hydrogen fluoride, and warehousing for storage; absorbing the obtained light component impurity gas by sulfuric acid, then carrying out the steps of S2-S4 again to obtain anhydrous hydrogen fluoride and waste gas, cooling the obtained anhydrous hydrogen fluoride by the pressure and sulfuric acid, and warehousing for storage;
s6, carrying out counter-current contact reaction on the obtained waste gas by fluosilicic acid, separating by using a filter cake to obtain concentrated fluosilicic acid and tail gas, returning the obtained concentrated fluosilicic acid to the steps S3-S5 for further purification and absorption to obtain purified anhydrous hydrogen fluoride, and warehousing for storage; the tail gas is treated by steps S1-S5, then is washed by water and then is discharged into the air, and the washed waste water washes the filter cake to complete the cycle process; the fluosilicic acid countercurrent contact reaction is that waste gas containing silicon fluoride passes through fluosilicic acid to generate a water-soluble reaction:
5SiF4+2H2O→2H2SiF6·SiF4+SiO2；
the silicon dioxide is separated by filtering the filter cake; and separating the generated silicon dioxide through a filter cake to obtain the concentrated fluosilicic acid through purification.
Example 4
Directly collecting hydrogen fluoride gas generated in the process of preparing ordinary calcium from white fertilizer and enriching calcium, purifying by adopting the method for preparing hydrogen fluoride in the process of producing feed-grade calcium hydrophosphate, and collecting the obtained purified hydrogen fluoride gas.
Table 1 was obtained by measuring the weight ratio of hydrogen fluoride in the hydrogen fluoride after purification in example 1, example 2, example 3, and example 4, and measuring the weight ratio of hydrogen fluoride after purification to the initially collected hydrogen fluoride gas.
TABLE 1 purified Hydrogen fluoride gas Condition
As can be seen from table 1, in the purification preparation method of the present invention, the condensing agent temperature is 15 ℃ and a multi-stage circulation manner is adopted, so that the obtained purified hydrogen fluoride is anhydrous hydrogen fluoride, the weight ratio of the hydrogen fluoride gas in the purified hydrogen fluoride is 99.5%, and the weight ratio of the purified hydrogen fluoride to the initially collected hydrogen fluoride gas is 85%, which represents the superiority of the present invention.
The foregoing is illustrative of the preferred embodiments of this invention, and it is to be understood that the invention is not limited to the precise form disclosed herein and that various other combinations, modifications, and environments may be resorted to, falling within the scope of the concept as disclosed herein, either as described above or as apparent to those skilled in the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (9)
1. A method for preparing hydrogen fluoride by purification is characterized in that: the method comprises the steps of purifying and preparing hydrogen fluoride gas generated in the process of preparing ordinary calcium and calcium-rich white fertilizer; the method comprises the following steps:
s1, drying the white fertilizer by heating, and collecting gas overflowing to a gas phase by adopting a double-shaft reaction mode;
s2, absorbing moisture and hydrogen fluoride by sulfuric acid to obtain primary crude hydrogen fluoride; absorbing the residual gas after absorption by water vapor and concentrating to obtain concentrated fluosilicic acid;
s3, preheating the obtained concentrated fluosilicic acid, and performing concentrated sulfuric acid action in a closed environment to obtain a mixed solution, and distilling the mixed solution to obtain a crude sulfuric acid diluent and secondary crude hydrogen fluoride;
s4, the obtained crude sulfuric acid diluent is purified by steam stripping to obtain fresh sulfuric acid, and the obtained fresh sulfuric acid is returned to the step; pre-purifying the obtained primary and secondary rough hydrogen fluoride to remove high-boiling point impurities to obtain I-grade hydrogen fluoride gas, condensing to obtain I-grade hydrogen fluoride liquid, pre-purifying the I-grade hydrogen fluoride liquid again to obtain II-grade hydrogen fluoride liquid, and drying the II-grade hydrogen fluoride liquid after pressure rectification to obtain anhydrous hydrogen fluoride and light component impurity gas;
s5, cooling the obtained anhydrous hydrogen fluoride by pressure and sulfuric acid to obtain purified anhydrous hydrogen fluoride, and warehousing for storage; absorbing the obtained light component impurity gas by sulfuric acid, then carrying out the steps of S2-S4 again to obtain anhydrous hydrogen fluoride and waste gas, cooling the obtained anhydrous hydrogen fluoride by the pressure and sulfuric acid, and warehousing for storage;
s6, carrying out counter-current contact reaction on the obtained waste gas by fluosilicic acid, separating by using a filter cake to obtain concentrated fluosilicic acid and tail gas, returning the obtained concentrated fluosilicic acid to the steps S3-S5 for further purification and absorption to obtain purified anhydrous hydrogen fluoride, and warehousing for storage; and (4) the tail gas is treated by steps S1-S5, then is washed by water and is discharged into the air, and the washed waste water is used for washing the filter cake, so that the circulating process is completed.
2. The process according to claim 1, wherein the hydrogen fluoride is prepared by the following steps: the fluosilicic acid countercurrent contact reaction is that waste gas containing silicon fluoride passes through fluosilicic acid to generate a water-soluble reaction:
5SiF4+2H2O→2H2SiF6·SiF4+SiO2；
the silica is separated by filtration through the filter cake.
3. The process according to claim 1, wherein the hydrogen fluoride is prepared by the following steps: the white fertilizer is dried by air flow, and the moisture of the white fertilizer is less than 1 percent as the full drying standard.
4. The process according to claim 1, wherein the hydrogen fluoride is prepared by the following steps: the pre-purification is to place the primary and secondary crude hydrogen fluoride gases in a pre-purification tower and remove high boiling point impurities by cooling in the tower.
5. The process according to claim 1, wherein the hydrogen fluoride is prepared by the following steps: the fresh sulfuric acid is sulfuric acid obtained by stripping the crude sulfuric acid diluent to remove hydrogen fluoride.
6. The process according to claim 5, wherein the hydrogen fluoride is prepared by: the mass fraction of the fresh sulfuric acid is 70-75%.
7. The process according to claim 1, wherein the hydrogen fluoride is prepared by the following steps: the condensation adopts two cascade condensers, and the temperature of a condensing agent is set to be 10-15 ℃.
8. The process according to claim 1, wherein the hydrogen fluoride is prepared by the following steps: the mixed liquid comprises sulfuric acid, water and hydrogen fluoride.
9. The process according to claim 1, wherein the hydrogen fluoride is prepared by the following steps: the light component impurity gas comprises sulfur dioxide and silicon fluoride.
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| CN112340703A (en) * | 2020-11-11 | 2021-02-09 | 四川大学 | Method for preparing anhydrous hydrogen fluoride and nano silicon dioxide by using fluosilicic acid |
| CN112374463A (en) * | 2020-11-19 | 2021-02-19 | 苏州金宏气体股份有限公司 | Purification method and purification system of hydrogen fluoride |
| CN112607708A (en) * | 2020-12-22 | 2021-04-06 | 四川大学 | Hydrogen fluoride gas treatment process |
| CN113479845A (en) * | 2021-08-10 | 2021-10-08 | 福建省清流县东莹化工有限公司 | Process and device for preparing anhydrous hydrogen fluoride by recovery method |
| CN115120998A (en) * | 2022-07-11 | 2022-09-30 | 多氟多新材料股份有限公司 | Method for improving hydrogen fluoride yield, and method and device for treating hydrogen fluoride tail gas |
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| CN113479845A (en) * | 2021-08-10 | 2021-10-08 | 福建省清流县东莹化工有限公司 | Process and device for preparing anhydrous hydrogen fluoride by recovery method |
| CN113479845B (en) * | 2021-08-10 | 2022-12-27 | 福建省清流县东莹化工有限公司 | Process and device for preparing anhydrous hydrogen fluoride by recovery method |
| CN115120998A (en) * | 2022-07-11 | 2022-09-30 | 多氟多新材料股份有限公司 | Method for improving hydrogen fluoride yield, and method and device for treating hydrogen fluoride tail gas |
| CN115120998B (en) * | 2022-07-11 | 2024-02-02 | 多氟多新材料股份有限公司 | Method for improving hydrogen fluoride yield, and treatment method and treatment device for hydrogen fluoride tail gas |
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