CN1363511A - Process for preparing fluorine compound and SiO2 from sodium fluosilicate - Google Patents
Process for preparing fluorine compound and SiO2 from sodium fluosilicate Download PDFInfo
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- CN1363511A CN1363511A CN 02112659 CN02112659A CN1363511A CN 1363511 A CN1363511 A CN 1363511A CN 02112659 CN02112659 CN 02112659 CN 02112659 A CN02112659 A CN 02112659A CN 1363511 A CN1363511 A CN 1363511A
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Abstract
A process for preparing fluorine compound and SiO2 from sodium fluorosilicate includes such steps as reaction of sodium fluorosilicate on ammonium fluoride, ammoniation to obtain slurry containing sodium fluoride, SiO2 and solution of ammonium fluoride, depositing, separating high-purity sodium fluoride, SiO2 (white carbon black) with large specific area and high-concentration NH4F solution from each other, and preparing fluoric compounds from said NH4F solution, such as ammonium (or sodium, or potassium) fluoride, etc.
Description
A method for producing fluorine compounds and silicon dioxide belongs to the field of inorganic chemical industry, and particularly relates to a method for producing fluorine compounds and depositing silicon dioxide (white carbon black) with a high specific surface by using sodium fluosilicate as a raw material.
In the production of phosphate fertilizer, in order to eliminate the pollution of fluorine-containing waste gas, most manufacturers absorb the fluorine-containing waste gas with water to prepare fluosilicic acid solution, and then further process the solution into sodium fluosilicate product. This is a low value and limited market capacity product, especially when many phosphate manufacturers are ascending the production of sodium fluorosilicate. Therefore, it is a matter of concern to convert it into a more economically valuable product with a wider market capacity.
The method for producing sodium fluoride by using sodium fluosilicate as a raw material is available in China, and sodium fluosilicate is decomposed by using sodium carbonate. Foreign countries also have methods for converting sodium fluorosilicate as a raw material. For example, in US patent US3656894, sodium fluorosilicate is aminated to remove filterable silica to obtain a mixed solution of sodium fluoride and ammonium fluoride, which is then reacted with a sodium aluminate solution to produce high quality cryolite. US patent 4057614 uses a two-step decomposition process to prepare sodium fluoride, the first step is to add sodium fluorosilicate to ammonium fluoride solution to obtain ammonium fluorosilicate containing sodium fluoride crystals and in a dissolved state; and secondly, adding ammonia into the mother liquor after the sodium fluoride is separated and crystallized, decomposing ammonium fluosilicate into silicon dioxide and ammonium fluoride, returning part of the ammonium fluoride solution after the silicon dioxide is separated to decompose the sodium fluosilicate, and adding sodium salt into the part of the ammonium fluoride solution to prepare the sodium fluoride.
The above methods, while feasible, all suffer from certain deficiencies. For example, soda ash is used as a raw material, and a large amount of soda ash withhigher price is consumed. The economic benefit is affected; US3656894 discloses a method for separating silicon dioxide formed by ammoniation, wherein the fluorine concentration in the obtained mixed fluorine solution of ammonium fluoride and sodium fluoride is only-3% F. The processing of such low concentration fluorine-containing solutions requires large processing equipment and high energy consumption, and the dissolution loss caused by a large amount of mother liquor greatly reduces the product yield. In US patent No. 4057614, the first step is to decompose sodium fluorosilicate with an ammonium fluoride solution, and since the ammonium fluoride has a weak reactivity, the decomposition rate of sodium fluorosilicate is only about 80%, and although the remaining sodium fluorosilicate can be completely decomposed when the solution from which sodium fluoride is separated in the second step is subjected to an amination treatment, the sodium fluoride produced in this step exists in a solid phase and is substantially lost with the separation of the silica solid phase. All the above methods for converting sodium fluorosilicate only pay attention to the utilization of fluorine and sodium elements, but neglect the utilization of silicon elements, so that the silicon elements appear in the form of silicon dioxide with less utilization value and are mostly discarded. It is clear that the ideal process for the conversion of sodium fluorosilicate is too efficient to utilize each of the elements in it and convert them to a product of higher economic value.
Therefore, the invention aims to provide an economical and effective method for producing fluorine compounds by fully utilizing each element in sodium fluosilicate and precipitating silica-white carbon black with high specific surface area. Wherein the fluorine compound may be sodium fluoride, ammonium fluoride, potassium fluoride, cryolite, etc.
The implementation of the invention comprises four steps: the first step is that sodium fluosilicate reacts with ammonium fluoride solution; the second step is ammoniation treatment of reactants; the third step is the separation of the sodium fluoride, silicon dioxide and ammonium fluoride solution; the fourth step is the further processing of the ammonium fluoride solution. Characterized in that the concentration of ammonium fluoride in the first reaction step is 25-40% NH4F, the dosage of which is 100-300% of the theoretical amount, the reaction temperature is 50-90 ℃, the reaction time is more than 20 minutes, and the reaction product is a heptafluoride compound NH consisting of sodium fluoride crystals, ammonium fluosilicate solution, ammonium fluosilicate and ammonium fluoride4F.(NH4)2SiF6Crystallizing, and ammoniating the reactant by a two-stage ammoniation method by using liquid ammonia, gas ammonia or gas ammonia containing water vapor at the temperature of 40-90 ℃. Controlling the pH value of a liquid phase to be 7.2-7.5 in a first stage and controlling the pH value of the liquid phase to be more than 8 in a second stage, then separating sodium fluoride crystals from an aminated material by using a gravity settling separation method, settling and drying to obtain a sodium fluoride product, aging the separated silicon dioxide and ammonium fluoride solution for more than 1 hour, separating the silicon dioxide by using a filtration separation method, washing and drying to obtain the product with the specific surface area of 100m2More than g of precipitated white carbon black product. The filtrate is 35-45% NH4A high concentration ammonium fluoride solution of F. Part of the filtrate and the washing liquid of the silicon dioxide are prepared into ammonium fluoride reaction liquid which is returned to the first step procedure for the reaction with the sodium fluosilicate, and the rest part of the ammoniumfluoride solution is further processed to prepare a plurality of fluorine compounds.
The first step of the method is the reaction of ammonium fluoride solution and sodium fluosilicate, and the reaction formula is as follows:
the reaction of this step is characterized by adopting high-concentration and high-dosage ammonium fluoride solution to react with sodium fluosilicate so as to obtain ammonium fluosilicateThe solution appears in the form of a solution, and a part of the solution is combined with ammonium fluoride and is treated with a heptafluoride compound NH4F.(NH4)2SiF6The solid form of (2) appears.
This is followed by an amination reaction, the slurry resulting from the first reaction step being aminated. At this time, the ammonium fluosilicate therein is converted into ammonium fluoride and silicon dioxide, and the reaction formula is:
because the reaction capacity of the ammonium fluoride is stronger, in the first step reaction, the sodium fluosilicate is difficult to completely decompose, and the sodium fluosilicate which is not decomposed can be completely decomposed under the condition of ammoniation reaction, and the reaction formula is as follows:
in order to obtain a high-concentration ammonium fluoride solution and precipitated white carbon black suitable for rubber reinforcement, liquid ammonia, gas ammonia or gas ammonia containing water vapor is used as an ammoniating agent, ammoniation is carried out in two stages, the pH value of a liquid phase is controlled to be 7.2-7.5 in the firststage, the pH value of the liquid phase is controlled to be more than 8 in the second stage, and the temperature in the ammoniation process is preferably controlled to be 50-70 degrees. The loss of ammonia will increase with too high a temperature.
The third step is to make the ammoniation reaction containing sodium fluoride, silicon dioxide and ammonium fluoride solutionThe slurry is subjected to an effective separation, which is the key to the present invention. Therefore, by utilizing the difference of the sedimentation velocity of the sodium fluoride and the silicon dioxide in the liquid phase and adopting a gravity separation method, the sodium fluoride with higher sedimentation velocity is separated out firstly, and the sodium fluoride product is prepared by filtering, washing and drying. And (3) aging the silicon dioxide suspended in the ammonium fluoride solution for more than 1 hour, separating by adopting a filtering separation method, and washing and drying to obtain the precipitated silicon dioxide-white carbon black product. The specific surface area can reach 100m2More than g. The filtrate obtained by filtering is a high-concentration ammonium fluoride solution, and the concentration of the ammonium fluoride solution can reach 35-45% of NH4F, mixing one part of the sodium fluosilicate with washing liquid, and returning to the first step for decomposing the sodium fluosilicate.
The fourth step is to process the obtained high-concentration ammonium fluoride solution to prepare ammonium fluoride, sodium fluoride, potassium fluoride, cryolite and the like.
When sodium salt is added, sodium fluoride is obtained. The addition of the sodium salt is usually more than 120% of the theoretical amount, and the reaction temperature is 40-90 ℃. Taking the addition of sodium chloride as an example, the reaction formula is:
because the concentration of the ammonium fluoride is higher, conditions are created for separating and recovering the sodium fluoride and the ammonium chloride from the mother liquor after the sodium fluoride is separated by adopting a thermal method, the separated sodium chloride can be returned to participate in the reaction with the ammonium fluoride solution, and the separated ammonium chloride can be sold as a byproduct.
The method for preparing cryolite is more particular, in order to prepare cryolite, sodium fluoride thick slurry or filter cake separated from ammoniated slurry by settlement and ammonium fluoride solution separated from silicon dioxide by filtration are combined into sodium fluoride and ammonium fluoride slurry without silicon dioxide, and the sodium fluoride and ammonium fluoride slurry react with sodium aluminate to prepare the cryolite, and the reaction formula is as follows:
when ammonium fluoride solution reacts with potassium hydroxide or potassium carbonate, potassium fluoride is produced, which reacts with potassium hydroxide according to the formula:
examples
Prepare 700 g of 32% NH4Solution F and 200 g of 99% Na2SiF6. In a reactor equipped with a stirrer, 150 g of 32% NH was added4And (3) slowly adding 43 g of sodium fluosilicate into the solution F at the temperature of 65 ℃, uniformly adding the rest ammonium fluoride solution and the sodium fluosilicate in proportion, wherein the whole feeding time is 1 hour, and continuously stirring and reacting for half an hour after the addition is finished. Controlling a certain speed to put the reaction slurry into a reactor with a small amount of 32% NH4In an ammoniation device with stirring for the F solution, andand introducing ammonia gas to keep the pH value of a liquid phase in the ammoniator at 7.2-7.5, after the reaction slurry is added, continuously introducing ammonia to raise the pH value of the liquid phase and keep the pH value above 8, and simultaneously controlling the temperature of the slurry within the range of 50-70 ℃. Stopping stirring after ammoniation, naturally settling, discharging upper suspension, adding dilute ammonium fluoride solution of saturated sodium fluoride (washing after filtering silicon dioxide)Liquid and washing liquid after filtering sodium fluoride), stirring and settling to discharge upper suspension, if the upper suspension is discharged for three times, washing sodium fluoride precipitate, drying at 105 ℃ to obtain 85.2 g of sodium fluoride with the purity of 99.2%, standing the discharged suspension after the first settling for 1 hour, filtering, washing a silicon dioxide filter cake in a counter current manner, finally washing the silicon dioxide filter cake with clear water until the eluate is nearly neutral, and drying at 120 ℃ to obtain 62.5 g of washing liquid with the specific surface area of 110m2Precipitated silica product/g, filtrate 42.3% NH4F in ammonium fluoride.
500 g of 42.3% NH were added to a reactor equipped with a stirrer4And (3) raising the temperature of the solution F, stabilizing the temperature at about 70 ℃, slowly adding 1336 g of 25.5% NaCl solution and 100 g of solid salt, continuing to react for 30 minutes after the addition is finished, filtering a product while the product is hot, washing the product with a saturated sodium fluoride aqueous solution, and drying the product to obtain 226 g of sodium fluoride with the purity of 99.2%. The filtrate is separated by a thermal separation method to separate ammonium chloride and sodium chloride, and the sodium chloride is returned to participate in the reaction for preparing sodium fluoride.
The method of the invention fully utilizes each element in the sodium fluosilicate to economically and effectively produce fluorine compounds and precipitated silica-white carbon black with high specific surface area, wherein the fluorine compounds comprise sodium fluoride, ammonium fluoride, potassium fluoride, cryolite and the like, and the method has higher economic benefit.
Claims (5)
1. The production method for preparing fluorine compounds and silicon dioxide by taking sodium fluosilicate as a raw material mainly comprises four steps: the first step is that sodium fluosilicate reacts with ammonium fluoride solution; the second step is ammoniation treatment of reactants; the third step is the separation of the sodium fluoride, silicon dioxide and ammonium fluoride solution; fourth step ofThe step is the further processing of the ammonium fluoride solution. Characterized in that the concentration of ammonium fluoride in the first reaction step is 25-40% NH4F, the using amount is 100-300% of the theoretical amount, the reaction temperature is 50-90 ℃, and the reaction time is more than 20 minutes. The reaction product is a heptafluoride compound NH consisting of sodium fluoride crystals, ammonium fluosilicate solution, ammonium fluosilicate and ammonium fluoride4F.(NH4F)2SiF6And (4) crystallizing. Ammoniating the reactant by using liquid ammonia, gas ammonia or gas ammonia containing water vapor at the temperature of 40-90 ℃ by using a two-stage ammoniation method, controlling the pH value of a liquid phase to be 7.2-7.5 in the first stage and controlling the pH value of the liquid phase to be more than 8 in thesecond stage, then separating fluoride crystals from the aminated material by using a gravity settling separation method, and washing and drying to obtain a sodium fluoride product; aging the separated silicon dioxide and ammonium fluoride solution for more than 1 hour, separating the silicon dioxide by adopting a filtering separation method, washing and drying to obtain the silicon dioxide with the specific surface area of 100m2More than one g of precipitated white carbon black product, namely filtrate which is 35-45% of NH4F, preparing ammonium fluoride reaction liquid from a high-concentration ammonium fluoride solution, part of filtrate and a silicon dioxide solution, and returning to the first step of the process for reacting with sodium fluosilicate. The remaining part of the ammonium fluoride solution is further processed to prepare a plurality of fluorine compounds. The above process can be realized by either a continuous or discontinuous production method.
2. The method for preparing fluorine compound and silica according to claim 1, wherein the washing separation liquid used in the method for separating sodium fluoride crystal by gravity settling is a dilute ammonium fluoride solution of saturated sodium fluoride, which is obtained from the washing liquid during the filtration of silica and the filtration and washing liquid of sodium fluoride crystal.
3. The process for producing fluorine compounds and silica according to claim 1, wherein the fluorine-containing compound is sodium fluoride or ammonium fluoride.
4. The process for producing fluorine compounds and silica according to claim 1, wherein the fluorine-containing compound is potassium fluoride or sodium fluoride.
5. The process according to claim 1, wherein the fluorine-containing compound is cryolite, and more particularly, wherein the cryolite is prepared by mixing a slurry or cake of sodium fluoride with a solution of ammonium fluoride.
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| Application Number | Priority Date | Filing Date | Title |
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| CN 02112659 CN1234596C (en) | 2002-02-08 | 2002-02-08 | Process for preparing fluorine compound and SiO2 from sodium fluosilicate |
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| CN 02112659 CN1234596C (en) | 2002-02-08 | 2002-02-08 | Process for preparing fluorine compound and SiO2 from sodium fluosilicate |
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| CN1363511A true CN1363511A (en) | 2002-08-14 |
| CN1234596C CN1234596C (en) | 2006-01-04 |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101269816A (en) * | 2008-05-16 | 2008-09-24 | 夏克立 | Method for producing fluorine series compounds and white carbon black |
| CN100577568C (en) * | 2006-03-01 | 2010-01-06 | 多氟多化工股份有限公司 | Method for linked production of ammonium acid fluoride and white carbon black |
| CN102320614A (en) * | 2011-09-01 | 2012-01-18 | 浙江矽昶绿能源有限公司 | Production method of high-purity silicon dioxide |
| CN102502669A (en) * | 2011-10-26 | 2012-06-20 | 瓮福（集团）有限责任公司 | Preparation method of nanometer silicon dioxide |
| CN102874821A (en) * | 2012-10-31 | 2013-01-16 | 天津舜能润滑科技股份有限公司 | Preparation method of high-purity silicon dioxide |
| CN103663476A (en) * | 2013-12-21 | 2014-03-26 | 瓮福（集团）有限责任公司 | Precipitation method for white carbon black production |
| CN105271244A (en) * | 2015-09-18 | 2016-01-27 | 武汉工程大学 | Method for synthesis of mesoporous molecular sieve and byproduct cryolite by use of fluosilicic acid |
| CN106865573A (en) * | 2017-04-16 | 2017-06-20 | 刘放放 | A kind of method that utilization lithium salts by-product nitration mixture prepares commercial fluorided sodium and industrial ammonium chloride |
| CN112119035A (en) * | 2018-05-08 | 2020-12-22 | “新化学产品”有限责任公司 | Method for treating hexafluorosilicic acid to produce hydrogen fluoride |
-
2002
- 2002-02-08 CN CN 02112659 patent/CN1234596C/en not_active Expired - Fee Related
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100577568C (en) * | 2006-03-01 | 2010-01-06 | 多氟多化工股份有限公司 | Method for linked production of ammonium acid fluoride and white carbon black |
| CN101269816A (en) * | 2008-05-16 | 2008-09-24 | 夏克立 | Method for producing fluorine series compounds and white carbon black |
| CN102320614B (en) * | 2011-09-01 | 2013-01-16 | 浙江矽昶绿能源有限公司 | Production method of high-purity silicon dioxide |
| CN102320614A (en) * | 2011-09-01 | 2012-01-18 | 浙江矽昶绿能源有限公司 | Production method of high-purity silicon dioxide |
| CN102502669B (en) * | 2011-10-26 | 2013-12-18 | 瓮福（集团）有限责任公司 | Preparation method of nanometer silicon dioxide |
| CN102502669A (en) * | 2011-10-26 | 2012-06-20 | 瓮福（集团）有限责任公司 | Preparation method of nanometer silicon dioxide |
| CN102874821A (en) * | 2012-10-31 | 2013-01-16 | 天津舜能润滑科技股份有限公司 | Preparation method of high-purity silicon dioxide |
| CN103663476A (en) * | 2013-12-21 | 2014-03-26 | 瓮福（集团）有限责任公司 | Precipitation method for white carbon black production |
| CN103663476B (en) * | 2013-12-21 | 2016-03-23 | 瓮福（集团）有限责任公司 | Intermediate processing in a kind of white carbon black production |
| CN105271244A (en) * | 2015-09-18 | 2016-01-27 | 武汉工程大学 | Method for synthesis of mesoporous molecular sieve and byproduct cryolite by use of fluosilicic acid |
| CN106865573A (en) * | 2017-04-16 | 2017-06-20 | 刘放放 | A kind of method that utilization lithium salts by-product nitration mixture prepares commercial fluorided sodium and industrial ammonium chloride |
| CN112119035A (en) * | 2018-05-08 | 2020-12-22 | “新化学产品”有限责任公司 | Method for treating hexafluorosilicic acid to produce hydrogen fluoride |
| CN112119035B (en) * | 2018-05-08 | 2024-01-16 | “新化学产品”有限责任公司 | Method for treating hexafluorosilicic acid to produce hydrogen fluoride |
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| CN1234596C (en) | 2006-01-04 |
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Address after: 104, room 7, 210019, Cui Shan garden, 198 prosperous Avenue, Jianye District, Jiangsu, Nanjing Patentee after: Xia Keli Address before: 210048 room 6, building 104, Xinhua three village, Dachang District, Jiangsu, Nanjing Patentee before: Xia Keli |
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