Method for producing sodium fluoride by using fluorobenzene hazardous waste

Abstract

The invention discloses a method for producing sodium fluoride by using fluorobenzene hazardous waste, the fluorobenzene hazardous waste is hydrofluoric acid mother liquor generated in a process for producing fluorobenzene by adopting an anhydrous hydrogen fluoride method, and the method comprises the following operation steps: S1) evaporating and concentrating the hydrofluoric acid mother liquor to separate out high-purity hydrogen fluoride so as to obtain concentrated mother liquor; s2) mixing the concentrated mother liquor obtained in the step S1) with methanol or ethanol in a stirring state, and reacting in a methanol or ethanol solution under the catalytic action to obtain a solid-liquid mixture; s3) filtering and separating the solid-liquid mixture obtained in the step S2) to obtain filter residues and filtrate; s4, the filter residues obtained in the step S3 are dried and smashed, and then high-purity sodium fluoride solid powder is obtained.The fluorobenzene hazardous waste-hydrofluoric acid mother liquor is efficiently treated, meanwhile, a continuous batch production process of high-grade, high-purity and high-quality sodium fluoride is formed, and the obtained high-grade sodium fluoride has a wide market prospect.

Description

Technical Field

[0001] The invention belongs to hazardous waste treatment technology in the field of fluorobenzene (chemical formula: C6H5F) production, and specifically relates to a method for producing sodium fluoride by utilizing fluorobenzene hazardous waste. Background Art

[0002] my country's fluorobenzene industry has developed rapidly and has gradually become the main supplier of the global fluorobenzene industry, with strong market competitiveness in the global fluorobenzene industry. In recent years, the fluorobenzene industry has adopted anhydrous hydrogen fluoride production technology to manufacture fluorobenzene, which has completely changed the backward situation of water production in the past, and has enabled the fluorobenzene industry to develop rapidly. In order to ensure the yield, the entire production process of the fluorobenzene industry will add excessive hydrogen fluoride. After the reaction is completed, a hydrofluoric acid mother liquor will be separated (its hydrofluoric acid content is usually around 70%, which is a hazardous waste). This hydrofluoric acid mother liquor is black-green in color, highly corrosive and toxic, difficult to handle, and has high processing costs.

[0003] Since this hydrofluoric acid mother liquor contains fluorine ions, hydrogen ions, sodium ions, tar, etc., it will cause serious corrosion to the equipment, resulting in an average service life of the equipment of only about 30 days. The hydrofluoric acid mother liquor will also cause serious pollution to the environment, destroy the ecological balance, and affect biodiversity; the fluorine ions therein will pose a great threat to human health. In addition, the hydrofluoric acid mother liquor is highly volatile and produces a large amount of white hydrogen fluoride smoke when it comes into contact with the air. People who are exposed to this type of hydrofluoric acid mother liquor for a long time may suffer from organ damage, cancer and other serious diseases. Therefore, the disposal of this hydrofluoric acid mother liquor is very urgent.

[0004] In the prior art, the commonly used method for treating the hydrofluoric acid mother liquor is the concentrated sulfuric acid method, that is, by adding a large amount of concentrated sulfuric acid, the water in the hydrofluoric acid is adsorbed by the concentrated sulfuric acid, and the hydrogen fluoride therein is evaporated by heating at high temperature. However, although the above treatment method and process can recover a certain amount of hydrogen fluoride, the recovery rate is not high, and a large amount of waste liquid containing sulfuric acid and hydrofluoric acid is generated, and there are still problems such as small consumption, complex treatment, and certain waste of hydrofluoric acid resources and environmental pollution.

[0005] In addition, the prior art also uses an acid-base neutralization method or a fluorine gas method to obtain sodium fluoride. The raw materials used in the acid-base neutralization method or the fluorine gas method are expensive, the reaction paths are dangerous and difficult, and it is difficult to achieve large-scale industrial application.

[0006] Therefore, the applicant hopes to seek technical solutions to solve the above technical problems. Summary of the invention

[0007] In view of this, the purpose of the present invention is to provide a method for producing sodium fluoride using fluorobenzene hazardous waste, which not only efficiently disposes of fluorobenzene hazardous waste - hydrofluoric acid mother liquor, but also forms a continuous batch production process for high-grade, high-purity, high-quality sodium fluoride. The obtained high-grade sodium fluoride has broad market prospects.

[0008] The technical solution adopted by the present invention is as follows: A method for producing sodium fluoride using fluorobenzene hazardous waste, wherein the fluorobenzene hazardous waste is produced by using anhydrous hydrogen fluoride The method comprises the following steps: S1), separating high-purity hydrogen fluoride from the hydrofluoric acid mother liquor by evaporation and concentration to obtain a concentrated mother liquor; S2), mixing the concentrated mother liquor obtained in the above step S1) with methanol or ethanol under stirring, Reaction is carried out under the action of the methanol or ethanol solution and catalyst to obtain a solid-liquid mixture; S3), filtering and separating the solid-liquid mixture obtained in the above step S2) to obtain a filter residue and a filtrate; S4), drying and crushing the filter residue obtained in the above step S3) to obtain high-purity sodium fluoride solid powder.

[0009] Preferably, in the step S1), the temperature range of evaporation concentration is 130-140° C., and evaporation is performed in an oil bath.

[0010] Preferably, in the step S1), the high-purity hydrogen fluoride separated by evaporation and concentration is subjected to condensation treatment, wherein the condensation temperature ranges from 0 to 5°C.

[0011] Preferably, in the step S2), the stirring speed is set to 120-170 rpm, and the stirring time is set to 20-40 minutes.

[0012] Preferably, in the step S2), the mass ratio of the concentrated mother liquor to methanol or ethanol is in the range of 1:1.1-1:1.35.

[0013] Preferably, in the step S3), filtration is performed using a polyfluoro filter cloth.

[0014] Preferably, the mesh size of the polytetrafluoroethylene filter cloth is 700-900 meshes.

[0015] Preferably, the method further comprises the following steps: S5), distill the filtrate obtained in the above step S3), collect the 68℃-78℃ distillate This fraction is used as the methanol or ethanol raw material in step S2).

[0016] Preferably, the purity of the high-purity sodium fluoride solid powder is not less than 99.9%, more preferably not less than 99.99%.

[0017] Preferably, in the step S1), both the evaporation concentration device and the condensation treatment device are made of polytetrafluoroethylene.

[0018] The present application adopts the hydrofluoric acid mother liquor hazardous waste (its hydrofluoric acid content is usually about 70%, containing fluorine ions, hydrogen ions, sodium ions, tar and other substances) generated in the process of producing fluorobenzene by anhydrous hydrogen fluoride as a raw material, and uses methanol or ethanol as a solvent and a catalyst to react with the concentrated mother liquor in an environment where methanol or ethanol is used as a solvent. Methanol or ethanol participates in the intermediate reaction and is resolved to obtain a solid-liquid mixture, wherein the solid phase is sodium fluoride and the liquid phase includes recyclable methanol or ethanol; the solid-liquid mixture is filtered, dried and crushed to obtain a high-purity sodium fluoride solid powder with analytical grade, and the fluorobenzene hazardous waste-hydrofluoric acid mother liquor is efficiently treated. At the same time, a continuous batch production process of high-grade, high-purity and high-quality sodium fluoride has been formed. The obtained high-grade sodium fluoride is an important fluoride salt and a raw material for manufacturing other fluorides. It can be used as an electrolyte additive, sodium ion battery raw material, agricultural pesticide, wood preservative, water treatment agent, light metal fluoride salt treatment agent, smelting and refining and protective layer, UF3 adsorbent in the nuclear industry, phosphating accelerator in the coating industry, spiritual flux and sunscreen agent for ceramics, glass and enamel, hide and skin treatment in the leather industry. The demand for high-quality sodium fluoride in various industrial fields in my country is huge and growing significantly, and it has broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a process flow chart of producing sodium fluoride from hazardous waste of fluorobenzene according to a specific embodiment of the present invention; Figure 2 This is the XRD diagram of the high-purity sodium fluoride solid powder obtained in Example 1 of the present application. DETAILED DESCRIPTION

[0020] See also Figure 1 As shown, a method for producing sodium fluoride using fluorobenzene hazardous waste, fluorobenzene hazardous waste is used as The hydrofluoric acid mother liquor produced in the process of producing fluorobenzene by anhydrous hydrogen fluoride method comprises the following steps: S1), separating high-purity hydrogen fluoride from the hydrofluoric acid mother liquor by evaporation and concentration to obtain a concentrated mother liquor; Preferably, in step S1), the temperature range of evaporation and concentration is 130-140°C, more preferably 132-138°C, and evaporation is performed in an oil bath; high-purity hydrogen fluoride is separated by evaporation and concentration and condensed, wherein the condensation temperature range is 0-5°C; further preferably, the evaporation and concentration device and the condensation treatment device used in this step are both made of polytetrafluoroethylene; S2), mixing the concentrated mother liquor obtained in the above step S1) with methanol or ethanol under stirring, The reaction is carried out under the action of a methanol or ethanol solution and a catalyst to obtain a solid-liquid mixture; preferably, in this step S2), the stirring speed is set to 120-170 rpm, more preferably 140-160 rpm; the stirring time is set to 20-40 minutes; the mass ratio of the concentrated mother liquor to the methanol or ethanol is in the range of 1:1.1-1:1.35; S3), filtering and separating the solid-liquid mixture obtained in the above step S2) to obtain a filter residue and a filtrate; Preferably, in step S3), PTFE filter cloth is used for filtering; further preferably, the mesh number of the PTFE filter cloth is 700-900 mesh; S4), drying and crushing the filter residue obtained in the above step S3) to obtain a high-purity sodium fluoride solid powder; preferably, the purity of the high-purity sodium fluoride solid powder obtained in this step is not less than 99.9%, more preferably not less than 99.99%; Preferably, in this embodiment, the following steps are also included: S5), distill the filtrate obtained in the above step S3), collect the 68℃-78℃ distillate This fraction is used as the methanol or ethanol raw material in step S2).

[0021] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0022] On the basis of the above implementation contents, in order to verify the technical effects achieved by the present application, the present application further proposes the following embodiments and comparative examples: Example 1: Please refer to Figure 1 As shown in the figure, the mother liquid of hydrofluoric acid produced in the process of producing fluorobenzene by anhydrous hydrogen fluoride method (black-green in color, with a hydrofluoric acid content of 70%, that is, Figure 1The "70% hydrofluoric acid mother liquor" shown in the figure) is put into a beaker made of polytetrafluoroethylene, and is heated in an oil bath with an evaporation temperature of 135°C to volatilize the hydrofluoric acid by heat, and condensed (the condenser is made of polytetrafluoroethylene and the condensation temperature is 3°C) to achieve evaporation pre-concentration treatment to obtain recyclable high-purity hydrogen fluoride, and a concentrated mother liquor is obtained in the beaker; the concentrated mother liquor is mixed with methanol (analytical grade, methanol concentration is not less than 95%, and the mass ratio of concentrated mother liquor to methanol is 1:1.2) at a stirring speed of 150 rpm, dissolved and catalytically reacted at room temperature and pressure for 30 minutes to obtain a solid-liquid mixture; the solid-liquid mixture is filtered using a 800-mesh polytetrafluoroethylene filter cloth to obtain a filter residue and a filtrate; the obtained filter residue is placed in an oven for drying, and the dried solid is crushed using a ball mill to obtain a high-purity sodium fluoride solid powder (i.e. Figure 1 The XRD pattern of "high-quality and high-purity sodium fluoride" shown in Figure 2 As shown, after testing, the purity of sodium fluoride is 99.993%; the filtrate is placed in a rotary evaporator, heated in a water bath, and the 68°C fraction is collected. This fraction is methanol, and the methanol is repeatedly used for mixed dissolution with the concentrated mother liquor and the methanol raw material for catalytic reaction.

[0023] Example 2: The rest of the technical scheme of Example 2 is the same as that of Example 1, except that, in Example 2, the methanol in Example 1 is replaced by ethanol (analytical grade, ethanol concentration is not less than 95%), and the mass ratio of concentrated mother liquor: ethanol is 1:1.35; after testing, the purity of the obtained sodium fluoride is 99.992%.

[0024] Embodiment 3: The rest of the technical scheme of Embodiment 3 is the same as that of Embodiment 1, except that, in Embodiment 3, the mass ratio of concentrated mother liquor to methanol is 1:1.1; upon testing, the purity of the obtained sodium fluoride is 99.991%.

[0025] Embodiment 4: The rest of the technical scheme of Embodiment 4 is the same as that of Embodiment 1, except that, in Embodiment 4, the mass ratio of concentrated mother liquor:methanol is 1:1.25. After testing, the purity of the obtained sodium fluoride is 99.99%.

[0026] Example 5: The rest of the technical scheme of Example 5 is the same as that of Example 1, except that, in Example 5, the mass ratio of concentrated mother liquor: methanol is 1:1. After testing, the purity of the obtained sodium fluoride is 99.97%.

[0027] Example 6: The rest of the technical scheme of Example 6 is the same as that of Example 1, except that, in Example 6, the mass ratio of concentrated mother liquor: methanol is 1:0.95. After testing, the purity of the obtained sodium fluoride is 98.6%.

[0028] Example 7: The rest of the technical scheme of Example 7 is the same as that of Example 1, except that, in Example 7, the mass ratio of concentrated mother liquor: methanol is 1:1.5. After testing, the purity of the obtained sodium fluoride is 98.6%.

[0029] Example 8: The rest of the technical scheme of Example 8 is the same as that of Example 1, except that, in Example 8, the mass ratio of concentrated mother liquor: methanol is 1:1.6. After testing, the purity of the obtained sodium fluoride is 99.5%.

[0030] Comparative Example 1: The remaining technical solutions of this comparative example 1 are the same as those of Example 1, except that, in this comparative example 1, methanol with a concentration of 35% is used to replace the methanol (analytical grade) in Example 1; after testing, the purity of the obtained sodium fluoride is 96.3%.

[0031] Comparative Example 2: The remaining technical solutions of this comparative example 2 are the same as those of Example 1, except that, in this comparative example 2, ethanol with a concentration of 45% is used to replace the methanol (analytical grade) in Example 1; after testing, the purity of the obtained sodium fluoride is 95.8%.

[0032] Comparative Example 3: The remaining technical solutions of Comparative Example 3 are the same as those of Example 1, except that, in Comparative Example 3, methanol with a concentration of 30% is used to replace the methanol (analytical grade) in Example 1; after testing, the purity of the obtained sodium fluoride is 92.4%.

[0033] Comparative Example 4: The remaining technical solutions of Comparative Example 4 are the same as those of Example 1, except that, in Comparative Example 4, methanol with a concentration of 25% is used to replace the methanol (analytical grade) in Example 1; after testing, the purity of the obtained sodium fluoride is 88.5%.

[0034] Comparative Example 5: The remaining technical solutions of this comparative example 5 are the same as those of Example 1, except that, in this comparative example 5, the evaporation pre-concentration treatment is cancelled, and the 70% hydrofluoric acid mother liquor is directly mixed with methanol at a stirring speed of 150 rpm, dissolved and catalytically reacted at normal temperature and pressure for 30 minutes to obtain a solid-liquid mixture; after testing, the purity of the obtained sodium fluoride is 78.3%.

[0035] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0036] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for producing sodium fluoride using fluorobenzene hazardous waste, wherein the fluorobenzene hazardous waste is a hydrofluoric acid mother liquor produced in the process of producing fluorobenzene using anhydrous hydrogen fluoride method, characterized in that: The steps are as follows: S1), separating high-purity hydrogen fluoride from the hydrofluoric acid mother liquor by evaporation and concentration to obtain a concentrated mother liquor. liquid; S2), mixing the concentrated mother liquor obtained in the above step S1) with methanol or ethanol under stirring, Reaction is carried out under the action of the methanol or ethanol solution and catalyst to obtain a solid-liquid mixture; S3), filtering and separating the solid-liquid mixture obtained in the above step S2) to obtain a filter residue and a filtrate; S4), drying and crushing the filter residue obtained in the above step S3) to obtain high-purity sodium fluoride solid powder.

2. The method for producing sodium fluoride using fluorobenzene hazardous waste according to claim 1, characterized in that: In the step S1), the temperature range of evaporation concentration is 130-140° C., and evaporation is performed in an oil bath.

3. The method for producing sodium fluoride using fluorobenzene hazardous waste according to claim 1, characterized in that: In the step S1), high-purity hydrogen fluoride is separated by evaporation and concentration and then condensed, wherein the condensation temperature ranges from 0 to 5°C.

4. The method for producing sodium fluoride using fluorobenzene hazardous waste according to claim 1, characterized in that: In the step S2), the stirring speed is set to 120-170 rpm, and the stirring time is set to 20-40 minutes.

5. The method for producing sodium fluoride using fluorobenzene hazardous waste according to claim 1, characterized in that: In the step S2), the mass ratio of the concentrated mother liquor to methanol or ethanol is in the range of 1:1.1-1:1.

35.

6. The method for producing sodium fluoride using fluorobenzene hazardous waste according to claim 1, characterized in that: In the step S3), filtration is performed using a polyfluoro filter cloth.

7. The method for producing sodium fluoride using fluorobenzene hazardous waste according to claim 6, characterized in that: The mesh number of the polytetrafluoroethylene filter cloth is 700-900 meshes.

8. The method for producing sodium fluoride using fluorobenzene hazardous waste according to claim 1, characterized in that: The following steps are also included: S5), distill the filtrate obtained in the above step S3), collect the 68℃-78℃ distillate This fraction is used as the methanol or ethanol raw material in step S2).

9. The method for producing sodium fluoride using fluorobenzene hazardous waste according to claim 1, characterized in that: The purity of the high-purity sodium fluoride solid powder is not less than 99.9%, and more preferably not less than 99.99%.

10. The method for producing sodium fluoride using hazardous waste fluorobenzene according to claim 3, characterized in that: In the step S1), both the evaporation concentration device and the condensation treatment device are made of polytetrafluoroethylene.

Images