CN113800524A - Concentration method of fluosilicic acid - Google Patents
Concentration method of fluosilicic acid Download PDFInfo
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- CN113800524A CN113800524A CN202111226699.XA CN202111226699A CN113800524A CN 113800524 A CN113800524 A CN 113800524A CN 202111226699 A CN202111226699 A CN 202111226699A CN 113800524 A CN113800524 A CN 113800524A
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- C01B33/00—Silicon; Compounds thereof
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- C01B33/103—Fluosilicic acid; Salts thereof
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Abstract
The invention provides a concentration method of fluosilicic acid, which comprises the following steps: a) and (3) carrying out gas-liquid contact on the dry air and the low-concentration fluosilicic acid to respectively obtain the concentrated fluosilicic acid and the wet air. Compared with the prior art, aiming at the low-concentration fluosilicic acid as a byproduct in the phosphorus chemical industry, the invention replaces the traditional concentration mode of heating and evaporation by adopting a mode of changing the quality of the absolutely dry air and the fluosilicic acid in a breakthrough manner, can keep a low-temperature state all the time in the concentration process, can effectively inhibit the self-decomposition of the fluosilicic acid, and has high single fluorine yield and low energy consumption; meanwhile, the obtained concentrated fluosilicic acid is not decomposed by the fluosilicic acid, so that the components of the concentrated fluosilicic acid are basically unchanged, and silica gel removal or other special treatment is not needed. Experimental results show that the concentration of the concentrated fluosilicic acid obtained by the concentration method provided by the invention is more than 35 wt%, the single fluorine yield can reach 99.8%, and the total fluorine yield can reach more than 95%.
Description
Technical Field
The invention relates to the technical field of fluosilicic acid, in particular to a method for concentrating fluosilicic acid.
Background
Over 90% of fluorine resources in nature are associated with phosphate ore. In the wet processing process of phosphorite, the associated fluorine of phosphorite is dissociated and then mainly escapes in the form of hydrogen fluoride and silicon tetrafluoride, and is absorbed into a low-concentration fluorosilicic acid solution through water washing, which accounts for about 30% of the total amount of the associated fluorine of phosphorite, and if the fluorine in the acid is treated by adopting a gas (steam) stripping defluorination process, the total fluorine yield can reach more than 60%. The fluorite resource in China is scarce, the reserves only account for 10 percent of the world, but the annual production capacity reaches more than 60 percent of the world, so that the fluorite storage ratio in China is far lower than the average level in the world. At present, phosphorus ore associated fluorine resource utilization becomes a focus of attention of people, but the byproduct fluosilicic acid is still mainly used for preparing sodium fluosilicate and other fluosilicates with low added values. The reason is mainly that the concentration of the by-product fluosilicic acid is low, generally only 10-20%, and the fluosilicic acid is easy to decompose along with the increase of temperature and concentration, so that the concentration is difficult, and the downstream application is severely limited.
At present, the method for concentrating the fluosilicic acid mainly comprises the following steps: CN103848426B 'method for concentrating fluosilicic acid by vacuum falling film evaporation', CN111017931A 'method for concentrating fluosilicic acid by high-temperature dilute sulphuric acid', and CN110240164A 'method and device for concentrating fluosilicic acid'; according to the technical scheme, vacuum falling film concentration is realized by supplying heat by different heat media, or hot air is directly heated and concentrated, and the fluosilicic acid is poor in thermal stability and easy to decompose into silicon tetrafluoride and hydrogen fluoride gas by heating, so that the decomposition of the fluosilicic acid is accelerated obviously, and the problems of single yield reduction, system operation energy consumption increase and the like are caused.
Disclosure of Invention
In view of the above, the present invention aims to provide a method for concentrating fluorosilicic acid, which can effectively inhibit the self-decomposition of fluorosilicic acid, and has high single fluorine yield and low energy consumption.
The invention provides a concentration method of fluosilicic acid, which comprises the following steps:
a) and (3) carrying out gas-liquid contact on the dry air and the low-concentration fluosilicic acid to respectively obtain the concentrated fluosilicic acid and the wet air.
Preferably, the temperature of the dry air in the step a) is 0-60 ℃, and the water content is less than 1g/Nm3。
Preferably, the preparation process of the dry air specifically comprises the following steps:
and introducing air into the packed tower, and circularly spraying and drying by adopting concentrated sulfuric acid to obtain dry air.
Preferably, the concentration of the concentrated sulfuric acid is 93 wt% to 98 wt%.
Preferably, the flow velocity of air in the packed tower is 0.5-2.5 m/s, and the gas ratio of concentrated sulfuric acid washing liquid is 3L/m3～6L/m3。
Preferably, the temperature of the low-concentration fluosilicic acid in the step a) is less than or equal to 40 ℃, and the concentration is 5-25 wt%.
Preferably, the means for gas-liquid contacting in step a) comprises a stripping means, an empty column or a packed column.
Preferably, the gas-liquid contact mode in step a) is not limited to countercurrent contact, and the gas-phase gas inlet mode is radial or tangential gas inlet; the flow velocity of the contact gas is 1-4 m/s, and the liquid-gas ratio is less than or equal to 7L/m3。
Preferably, the gas-liquid contact time in step a) is 4s to 10 s.
Preferably, the step a) further comprises:
and (4) defoaming, condensing, separating and washing the wet air, and then emptying.
The invention provides a concentration method of fluosilicic acid, which comprises the following steps: a) and (3) carrying out gas-liquid contact on the dry air and the low-concentration fluosilicic acid to respectively obtain the concentrated fluosilicic acid and the wet air. Compared with the prior art, aiming at the low-concentration fluosilicic acid as a byproduct in the phosphorus chemical industry, the invention replaces the traditional concentration mode of heating and evaporation by adopting a mode of changing the quality of the absolutely dry air and the fluosilicic acid in a breakthrough manner, can keep a low-temperature state all the time in the concentration process, can effectively inhibit the self-decomposition of the fluosilicic acid, and has high single fluorine yield and low energy consumption; meanwhile, the obtained concentrated fluosilicic acid is not decomposed by the fluosilicic acid, so that the components of the concentrated fluosilicic acid are basically unchanged, and silica gel removal or other special treatment is not needed. Experimental results show that the concentration of the concentrated fluosilicic acid obtained by the concentration method provided by the invention is more than 35 wt%, the single fluorine yield can reach more than 99%, and the total fluorine yield can reach more than 95%.
In addition, the wet air discharged after being concentrated by the concentration method provided by the invention can be directly discharged after being defoamed, condensed and separated and washed by a washing tower, so that the energy consumption of the system is lower, the realization is easier, and the industrialization is more economic.
Drawings
Fig. 1 is a flow chart of a method for concentrating fluosilicic acid provided by the embodiment of the invention.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a concentration method of fluosilicic acid, which comprises the following steps:
a) and (3) carrying out gas-liquid contact on the dry air and the low-concentration fluosilicic acid to respectively obtain the concentrated fluosilicic acid and the wet air.
Referring to fig. 1, fig. 1 is a flow chart of a method for concentrating fluosilicic acid according to an embodiment of the present invention. The invention makes the dry air and the low-concentration fluosilicic acid contact with each other in a gas-liquid manner. In the present invention, the temperature of the dry air is preferably 0 to 60 ℃, more preferably 0 to 50 ℃; the water content of the dry air is preferably < 1g/Nm3More preferably ≦ 0.1g/Nm3. The invention adopts the absolute dry air and the low-concentration fluosilicic acid for quality change, takes away the moisture in the dilute fluosilicic acid by using the dry air with extremely small water content to achieve the concentration effect, can effectively inhibit the self decomposition of the fluosilicic acid at the temperature, and is essentially different from the prior technology of concentrating the fluosilicic acid by depending on a heating mode.
In the invention, the dry air can be obtained by concentrated sulfuric acid treatment, freezing, adsorption drying of compressed air and other ways of removing moisture in air. In a preferred embodiment of the present invention, the preparation process of the dry air specifically comprises:
and introducing air into the packed tower, and circularly spraying and drying by adopting concentrated sulfuric acid to obtain dry air.
In the invention, the concentration of the concentrated sulfuric acid is preferably 93-98 wt%; after the concentrated sulfuric acid is used for preparing dry air, the obtained dilute sulfuric acid (the concentration is reduced from 93 wt% -98 wt% to 80 wt% -95 wt%, and the sulfuric acid is not polluted) is equal to low-concentration sulfuric acid diluted by water, can be directly recycled by a sulfuric acid system for recycling, and can also be used for producing phosphoric acid or any occasions using the dilute sulfuric acid.
In the present invention, the flow rate of air in the packed tower is preferably 0.5 to 2.5m/s, more preferably 0.8 to 2 m/s; the gas ratio of concentrated sulfuric acid washing liquid in the packed tower is preferably 3L/m3～6L/m3More preferably 4L/m3～5L/m3。
In the invention, the concentration of the low-concentration fluosilicic acid is 5-25 wt%, preferably 15-20 wt%; the source of the low-concentration fluosilicic acid is not particularly limited by the invention, and the low-concentration fluosilicic acid which is a byproduct in the phosphorus chemical industry and is well known to those skilled in the art can be adopted. The fluosilicic acid with the concentration is difficult to directly utilize, the fluosilicic acid has poor thermal stability, the fluosilicic acid is easy to decompose into silicon tetrafluoride and hydrogen fluoride gas when being heated, and the concentration difficulty is large; the prior art uses a concentration mode that the concentration is improved by heating fluosilicic acid to evaporate water in the fluosilicic acid.
In the present invention, the temperature of the low-concentration fluorosilicic acid is preferably 40 ℃ or lower.
In the present invention, the means for gas-liquid contacting preferably comprises a stripping means, an empty column or a packed column, more preferably an empty column. The source of the gas-liquid contact device is not particularly limited in the invention, and the above-mentioned equipment capable of realizing gas-liquid exchange, which is well known to those skilled in the art, can be adopted.
In the present invention, the gas-liquid contact is not limited to the countercurrent contact, and the gas phaseThe air inlet mode is radial or tangential air inlet; preferably countercurrent contact, thereby ensuring better gas-liquid quality change effect. In the present invention, the contact gas flow rate is preferably 1m/s to 4m/s, more preferably 1.5m/s to 3 m/s; the ratio of the contacted liquid to gas (low-concentration fluosilicic acid to dry air) is preferably less than or equal to 7L/m3More preferably 3.5L/m3～7L/m3。
In the present invention, the gas-liquid contact time is preferably 4s to 10s, more preferably 5s to 8 s.
In the present invention, the step a) preferably further comprises:
and (4) defoaming, condensing, separating and washing the wet air, and then emptying. The device for defoaming, condensing, separating and washing is not particularly limited and can be a device well known to those skilled in the art. The invention directly empties the concentrated and discharged wet air after defoaming, condensation separation and washing, has lower energy consumption of the system, is easier to realize and is more economical in industrialization.
Aiming at the low-concentration fluosilicic acid as a byproduct in the phosphorus chemical industry, the invention replaces the traditional concentration mode of heating evaporation with a mode of changing the quality of the absolutely dry air and the fluosilicic acid, and can keep a low-temperature state all the time in the concentration process, thereby effectively inhibiting the self-decomposition of the fluosilicic acid, and having high yield of single fluorine and low energy consumption; meanwhile, the obtained concentrated fluosilicic acid is not decomposed by the fluosilicic acid, so that the components of the concentrated fluosilicic acid are basically unchanged, and silica gel removal or other special treatment is not needed.
To further illustrate the present invention, the following examples are provided for illustration.
Example 1
(1) Introducing clean air into a packed tower, adopting 93-95 wt% concentrated sulfuric acid for circulating spray drying, controlling the gas flow rate in the packed tower at 0.8-1.5 m/s, and controlling the gas ratio of concentrated sulfuric acid washing liquid at 4L/m3～5L/m3The temperature is 40-50 ℃, and the water content is 0.8g/Nm3Dry air.
(2) Introducing the dry air obtained in the step (1) into an empty tower concentration tower, carrying out countercurrent exchange with fluosilicic acid with the concentration of 18 wt% (not more than 40 ℃),controlling the gas ratio of the washing liquid to be 5L/m3～7L/m3The gas velocity of the empty tower is 2-3 m/s, the retention time is 6-7 s, the fluosilicic acid with the concentration of 35.4wt percent (less than or equal to 40 ℃) is obtained, the single fluorine yield is 99.8 percent, and the total fluorine yield is 95.8 percent; in addition, wet air is obtained and enters the rear end for defoaming, condensation separation and washing, and then is exhausted after reaching the standard.
Example 2
(1) Introducing clean air into a packed tower, circularly spraying and drying by adopting 95-98 wt% concentrated sulfuric acid, controlling the gas flow rate in the packed tower to be 0.8-1.5 m/s and the gas ratio of concentrated sulfuric acid washing liquid to be 4L/m3～5L/m3The temperature is 40-50 ℃, and the water content is 0.1g/Nm3Dry air.
(2) Introducing the dry air obtained in the step (1) into an empty tower concentration tower, carrying out countercurrent exchange with 20 wt% fluosilicic acid (the temperature is less than or equal to 40 ℃), and controlling the gas-to-gas ratio of the washing liquid to be 6L/m3～7L/m3The gas velocity of the empty tower is 1.5-2.5 m/s, the retention time is 6-8 s, fluosilicic acid with the concentration of 37.1wt percent (less than or equal to 40 ℃) is obtained, the single fluorine yield is 99.5 percent, and the total fluorine yield is 96.7 percent; in addition, wet air is obtained and enters the rear end for defoaming, condensation separation and washing, and then is exhausted after reaching the standard.
Example 3
(1) Introducing clean air into a packed tower, adopting 93-95 wt% concentrated sulfuric acid for circulating spray drying, controlling the gas flow rate in the packed tower to be 1.5-2 m/s, and controlling the gas ratio of concentrated sulfuric acid washing liquid to be 4L/m3～5L/m3The temperature is 40-50 ℃, and the water content is 0.5g/Nm3Dry air.
(2) Introducing the dry air obtained in the step (1) into an empty tower concentration tower, carrying out countercurrent exchange with fluosilicic acid with the concentration of 15 wt% (not more than 40 ℃), and controlling the gas-to-gas ratio of the washing liquid to be 3.5L/m3～5L/m3The gas velocity of the empty tower is 2-3 m/s, the retention time is 5-6 s, the fluosilicic acid with the concentration of 39.7wt percent (less than or equal to 40 ℃) is obtained, the single fluorine yield is 99.3 percent, and the total fluorine yield is 95.6 percent; in addition, wet air is obtained and enters the rear end for defoaming, condensation separation and washing, and then is exhausted after reaching the standard.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A method for concentrating fluosilicic acid comprises the following steps:
a) and (3) carrying out gas-liquid contact on the dry air and the low-concentration fluosilicic acid to respectively obtain the concentrated fluosilicic acid and the wet air.
2. The method of concentration according to claim 1, wherein the temperature of the dry air in step a) is 0 ℃ to 60 ℃ and the water content is < 1g/Nm3。
3. The concentration method according to claim 2, wherein the dry air is prepared by:
and introducing air into the packed tower, and circularly spraying and drying by adopting concentrated sulfuric acid to obtain dry air.
4. The concentration method according to claim 3, wherein the concentration of the concentrated sulfuric acid is 93 wt% to 98 wt%.
5. The concentration method according to claim 3, wherein the flow rate of air in the packed tower is 0.5-2.5 m/s, and the gas ratio of concentrated sulfuric acid washing liquid is 3L/m3～6L/m3。
6. The concentration method according to claim 1, wherein the temperature of the low-concentration fluosilicic acid in the step a) is less than or equal to 40 ℃ and the concentration is 5-25 wt%.
7. The method of claim 1, wherein the means for contacting the gas and liquid in step a) comprises a stripping means, an empty column or a packed column.
8. The concentration method according to claim 1, wherein the gas-liquid contact mode in step a) is not limited to countercurrent contact, and the gas-phase gas inlet mode is radial or tangential gas inlet; the flow velocity of the contact gas is 1-4 m/s, and the liquid-gas ratio is less than or equal to 7L/m3。
9. The method according to claim 1, wherein the gas-liquid contact time in step a) is 4 to 10 seconds.
10. The concentration method according to any one of claims 1 to 9, wherein the step a) further comprises:
and (4) defoaming, condensing, separating and washing the wet air, and then emptying.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116425167A (en) * | 2023-04-19 | 2023-07-14 | 贵州瓮福蓝天氟化工股份有限公司 | Concentration method and system of fluosilicic acid solution |
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| US3645679A (en) * | 1970-03-09 | 1972-02-29 | Wellman Lord Inc | Concentrating fluosilicic acid |
| CN1974380A (en) * | 2006-11-09 | 2007-06-06 | 湖北三新磷酸有限公司 | Phosphorus and flourine absorbing and separating method in preparing kiln process phosphoric acid |
| CN103848426A (en) * | 2014-02-25 | 2014-06-11 | 瓮福（集团）有限责任公司 | Method for concentrating fluosilicic acid by utilizing vacuum falling film evaporation method |
| CN110240164A (en) * | 2019-06-26 | 2019-09-17 | 威海恒邦化工有限公司 | The method and device of fluosilicic acid concentration |
| CN112717443A (en) * | 2020-12-22 | 2021-04-30 | 四川大学 | Concentration process of fluosilicic acid |
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- 2021-10-21 CN CN202111226699.XA patent/CN113800524A/en active Pending
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| US3645679A (en) * | 1970-03-09 | 1972-02-29 | Wellman Lord Inc | Concentrating fluosilicic acid |
| CN1974380A (en) * | 2006-11-09 | 2007-06-06 | 湖北三新磷酸有限公司 | Phosphorus and flourine absorbing and separating method in preparing kiln process phosphoric acid |
| CN103848426A (en) * | 2014-02-25 | 2014-06-11 | 瓮福（集团）有限责任公司 | Method for concentrating fluosilicic acid by utilizing vacuum falling film evaporation method |
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| CN116425167A (en) * | 2023-04-19 | 2023-07-14 | 贵州瓮福蓝天氟化工股份有限公司 | Concentration method and system of fluosilicic acid solution |
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