CN107777691B - Method for recovering fluorine resource in acidic fluorine-containing wastewater - Google Patents
Method for recovering fluorine resource in acidic fluorine-containing wastewater Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/113—Silicon oxides; Hydrates thereof
- C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
- C01B33/126—Preparation of silica of undetermined type
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B7/00—Halogens; Halogen acids
- C01B7/19—Fluorine; Hydrogen fluoride
- C01B7/191—Hydrogen fluoride
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B7/00—Halogens; Halogen acids
- C01B7/19—Fluorine; Hydrogen fluoride
- C01B7/191—Hydrogen fluoride
- C01B7/195—Separation; Purification
- C01B7/196—Separation; Purification by distillation
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/12—Halogens or halogen-containing compounds
- C02F2101/14—Fluorine or fluorine-containing compounds
Abstract
The invention provides a method for recovering fluorine resources in acidic fluorine-containing wastewater, which comprises the following steps: evaporating the acidic fluorine-containing wastewater to obtain an evaporation condensate and an evaporation concentrate; adding metal fluoride salt into the evaporation condensate for reaction, then carrying out solid-liquid separation to obtain a solid filter cake and filtrate, and carrying out rectification and purification on the obtained filtrate to obtain a hydrofluoric acid solution; carrying out carbon-base decomposition reaction on the solid filter cake and a metal carbonate solution to obtain slurry containing metal fluoride and slurry containing silica colloid, and then respectively obtaining a filter cake containing the metal fluoride and a filter cake containing the silica colloid through solid-liquid separation; drying a part of filter cake containing metal fluoride salt, and reacting with sulfuric acid to obtain anhydrous hydrogen fluoride; and drying the filter cake containing the silica colloid to prepare the white carbon black. The method can economically and efficiently recover resources such as fluorine, silicon and the like from the fluorine-containing wastewater, greatly reduce the treatment cost of the fluorine-containing wastewater and simplify the treatment process.
Description
Technical Field
The invention belongs to the field of inorganic fluorine resource recovery, relates to a method for recovering fluorine resources in acidic fluorine-containing wastewater, and particularly relates to a method for recovering fluorine resources from acidic fluorine-containing wastewater in niobium-tantalum hydrometallurgy industry and/or phosphate fertilizer industry.
Background
The fluorine chemical products are called gold industry because of the characteristics of multiple varieties, excellent performance, wide application field, high added value and the like. On one hand, fluorite is also called fluorite, has become a national strategic resource and has the characteristics of co-occurrence and less rich ores, but most fluorites are difficult to be selected, and the resource consumption is fast, so the guarantee degree is seriously insufficient; on the other hand, the water environment has great potential harm of fluorine pollution and serious fluorine resource waste.
Wastewater discharged in the industries of chemical industry, nonferrous metallurgy, glass, electronics, electroplating and the like often contains high-concentration fluoride, most of fluorine elements in the fluorine-containing wastewater enter fluorine-containing sludge in a solid form, secondary pollution is easily caused in the processes of storage, transportation and disposal, and once underground water or soil pollution is caused, an ecological system is extremely difficult to recover. Therefore, the economic and efficient recovery of the fluorine resources in the wastewater is beneficial to relieving the bottleneck problems of resources and environmental protection, and the reduction, harmlessness and recycling of the fluorine-containing wastewater are significant.
Because of different sources and great difference of physicochemical properties of the fluorine-containing wastewater, the wastewater has more fluorine removal methods, which mainly comprise a chemical precipitation method, an adsorption method, a coagulation sedimentation method and the like. Among them, the lime neutralization precipitation method is most widely used for treating high-concentration fluorine-containing wastewater, and CN 1962475a discloses a method and an apparatus for treating fluorine-containing wastewater with limestone, which comprises using natural limestone as a raw material, using an acid capable of generating a soluble calcium salt by a chemical reaction with the limestone as an intermediate medium, generating calcium fluoride hardly soluble in water and an acidic intermediate medium by a reaction between the soluble calcium salt generated in the reaction and fluorine ions in the fluorine-containing wastewater, and reacting the fluorine-containing ions in the intermediate medium to treat the fluorine-containing wastewater. However, the above method has problems that lime consumption is large, neutralized slag is difficult to filter and has a high water content, and it is difficult to use the slag and becomes a new pollution source.
The adsorption method utilizes an adsorbent or ion exchange to treat the low-fluorine-content wastewater, and has simple process. For example, CN104944506A discloses a method for treating fluorine-containing wastewater, which comprises the following steps: soaking activated carbon in an aluminum salt solution, filtering to obtain filter residue, drying at 120 ℃, washing and drying to obtain a modified activated carbon adsorbent; and (3) throwing the modified activated carbon adsorbent into the fluorine-containing wastewater to be treated, and removing fluorine ions in the wastewater by means of oscillation adsorption. However, the above method has the disadvantages of small adsorption capacity, difficult regeneration and large dosage of the adsorbent, low selectivity, poor recycling performance, and the like.
The coagulation sedimentation method mainly utilizes hydrolytic flocculation products such as ferric salt, aluminum salt and the like to adsorb or complex fluorine ions in the wastewater. CN104803522A discloses a method for treating high-sodium fluorine-containing wastewater, which adopts lime as a precipitator and polyacrylamide as a flocculating agent to treat the high-sodium fluorine-containing wastewater, wherein the fluorine content of effluent can be stably reduced to below 5 mg/L.
Other fluorine removal methods comprise a freezing method, an ultrafiltration method, electrodialysis and the like, but the treatment cost is high, the fluorine removal efficiency is low, the method still stays in an experimental stage till now, and the popularization and the application are difficult.
Therefore, the prior technical scheme for treating and recovering the fluorine-containing wastewater has the problems of large lime consumption, difficult regeneration and large consumption of the adsorbent, complex treatment process, high treatment cost and the like. Therefore, it is very important to research a method for economically and efficiently recovering fluorine resources from fluorine-containing wastewater.
Disclosure of Invention
Aiming at the problems of large lime consumption, difficult regeneration and large consumption of an adsorbent, complex treatment process, high treatment cost and the like in the conventional technical scheme for treating and recovering fluorine from the fluorine-containing wastewater, the invention provides a method for recovering fluorine resources from the acidic fluorine-containing wastewater. The method recovers the fluorine resource in the acidic fluorine-containing wastewater in the form of hydrofluoric acid or anhydrous hydrogen fluoride, and can recover more than 90% of the fluorine resource in the acidic fluorine-containing wastewater in niobium-tantalum industry and phosphate fertilizer industry. The obtained hydrofluoric acid and the like can be directly used as hydrometallurgy raw materials or raw materials for preparing various fluorine-containing compounds, and has wide application. In addition, the method can reduce the amount of the treated fluorine-containing wastewater by more than 70 percent, greatly reduce the treatment cost of the fluorine-containing wastewater and simplify the treatment process; the treated fluorine-containing wastewater is easy to realize the comprehensive utilization of other metal resources and other non-volatile acids, thereby solving the technical problems of reduction, harmlessness and recycling of the fluorine-containing wastewater.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a method for recovering fluorine resources in acidic fluorine-containing wastewater, which comprises the following steps:
(1) evaporating the acidic fluorine-containing wastewater to obtain an evaporation condensate and an evaporation concentrate;
(2) adding metal fluoride salt into the evaporation condensate obtained in the step (1) for reaction, carrying out solid-liquid separation on the slurry after the reaction to obtain a solid filter cake and filtrate, and rectifying and purifying the obtained filtrate to obtain a hydrofluoric acid solution;
(3) carrying out carbon-base decomposition reaction on the solid filter cake obtained in the step (2) and a metal carbonate solution to obtain slurry containing metal fluoride salt and slurry containing silica colloid, carrying out solid-liquid separation on the obtained slurry containing metal fluoride salt to obtain a filter cake containing metal fluoride salt and filtrate, and carrying out solid-liquid separation on the obtained slurry containing silica colloid to obtain a filter cake containing silica colloid and filtrate;
(4) returning one part of the filter cake containing the metal fluoride salt obtained in the step (3) to the step (2) for reaction, and drying the other part of the filter cake and reacting the dried filter cake with sulfuric acid to obtain anhydrous hydrogen fluoride; and (4) drying the filter cake containing the silica colloid obtained in the step (3) to obtain the white carbon black.
In the invention, the carbon-base decomposition reaction is carried out in a normal-pressure tank reactor.
In the present invention, the "one part" and the "another part" mean that the filter cake containing the metal fluoride salt is divided into two parts, i.e., "one part" and "another part", as is clear.
In the invention, the fluorine resource in the acid fluorine-containing wastewater is recovered in the form of hydrofluoric acid or anhydrous hydrogen fluoride by adding metal fluoride salt to the concentrated acid fluorine-containing wastewater. In the whole process, the metal fluoride salt is added into the wastewater once, so that the metal fluoride salt can be generated through subsequent reaction and recycled, and the material consumption is greatly saved; and no waste liquid is generated in the whole process, so that the method is more economic and environment-friendly, and the technical problems of reduction, harmlessness and recycling of the fluorine-containing wastewater are solved.
The following technical solutions are preferred but not limited to the technical solutions provided by the present invention, and the technical objects and advantages of the present invention can be better achieved and realized by the following technical solutions.
As a preferable technical scheme of the invention, the acidic fluorine-containing wastewater in the step (1) is acidic fluorine-containing wastewater discharged by niobium-tantalum hydrometallurgy industry and/or phosphate fertilizer industry, and is further preferably acidic fluorine-containing wastewater in the niobium-tantalum hydrometallurgy industry.
In the invention, the fluorine ion content in the acidic fluorine-containing wastewater is about 110-170 g/L, and the silicon ion content is about 10-40 g/L.
Preferably, the acid concentration in the acidic fluorine-containing wastewater in step (1) is > 10N. Here, the acid concentration is an equivalent concentration.
In a preferred embodiment of the present invention, the evaporation temperature in the evaporation in the step (1) is 80 to 180 ℃, for example, 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃, 160 ℃, 170 ℃ or 180 ℃, but is not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable, and more preferably 110 to 160 ℃.
Preferably, the degree of vacuum of the evaporation in the step (1) is 0 to 90kPa, for example, 1kPa, 10kPa, 20kPa, 30kPa, 40kPa, 50kPa, 60kPa, 70kPa, 80kPa or 90kPa, but is not limited to the recited values, and other values not recited in the range of the recited values are also applicable, and more preferably 10 to 70 kPa.
Preferably, the evaporation concentrated solution in the step (1) is sequentially cooled, recovered and extracted to obtain valuable metal elements, and then neutralized by lime milk and discharged.
In the invention, the evaporated concentrated solution is cooled to obtain titanium-rich and iron-rich solid slag and a liquid phase taking concentrated sulfuric acid as a main component, the liquid phase is neutralized by lime milk for harmless treatment, and the liquid phase can also be used for preparing anhydrous hydrogen fluoride or be circularly used as a hydrometallurgy medium instead of the concentrated sulfuric acid.
In a preferred embodiment of the present invention, the metal fluoride salt in step (2) is sodium fluoride and/or potassium fluoride, and more preferably sodium fluoride.
Preferably, the metal fluoride salt in step (2) is added in solid and/or liquid form.
Preferably, the molar ratio of the metal fluoride salt added in step (2) to the silicon element in the evaporation condensate is (1.9 to 2.4):1, for example, 1.9:1, 2:1, 2.1:1, 2.2:1, 2.3:1, or 2.4:1, but not limited to the enumerated values, and other values within the numerical range are also applicable, and more preferably (2.0 to 2.3): 1.
Preferably, the reaction temperature of the reaction in step (2) is 10 to 90 ℃, for example, 10 ℃, 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃ or 90 ℃, but not limited to the recited values, and other values not recited in the range of the values are also applicable.
In a preferred embodiment of the present invention, the hydrofluoric acid solution in the step (2) has a mass concentration of 5 to 20%, for example, 5%, 7%, 10%, 13%, 15%, 17%, or 20%, but the concentration is not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable.
As a preferable technical scheme of the invention, the metal carbonate in the step (3) is sodium carbonate and/or potassium carbonate.
In the invention, the solid filter cake and the metal carbonate solution are subjected to a carbon-alkali decomposition reaction, and the chemical reaction can be expressed as follows:
Na2SiF6+Me2CO3→2NaF+4MeF+SiO2↓+2CO2↑
preferably, the metal carbonate solution in step (3) has a mass concentration of 10 to 30%, for example, 10%, 15%, 20%, 25%, or 30%, but not limited to the recited values, and other values not recited in the range of the values are also applicable.
In a preferred embodiment of the present invention, the reaction temperature of the carbon-base decomposition reaction in the step (3) is 50 to 110 ℃, for example, 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃, 95, 100 ℃, 105 ℃ or 110 ℃, but the reaction temperature is not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable, and more preferably 80 to 100 ℃.
Preferably, the reaction time of the carbon-base decomposition reaction in step (3) is 0.5 to 2 hours, for example, 0.5 hour, 1 hour, 1.5 hour or 2 hours, but not limited to the recited values, and other values within the range are also applicable, and more preferably 30 to 90 min.
As a preferable technical scheme of the invention, the filtrate obtained in the step (3) is returned to participate in the carbon-base decomposition reaction.
As a preferred embodiment of the present invention, the sulfuric acid used in the step (4) has a mass concentration of 98%.
Preferably, the anhydrous hydrogen fluoride prepared in the step (4) is absorbed by the hydrofluoric acid solution obtained in the step (2). And (3) absorbing by using the hydrofluoric acid solution obtained in the step (2) so as to prepare a hydrofluoric acid product with higher concentration.
As a preferred technical scheme of the invention, the method comprises the following steps:
(1) evaporating the acidic fluorine-containing wastewater at the temperature of 110-160 ℃ and the vacuum degree of 10-70 kPa to obtain an evaporation condensate and an evaporation concentrate;
(2) adding sodium fluoride into the evaporation condensate obtained in the step (1) to react at 10-90 ℃, performing solid-liquid separation on the slurry after the reaction to obtain a solid filter cake and a filtrate, wherein the molar ratio of the added sodium fluoride to silicon element in the evaporation condensate is (2.0-2.3): 1, and rectifying and purifying the obtained filtrate to obtain a hydrofluoric acid solution with the mass concentration of 5-20%;
(3) carrying out carbon-base decomposition reaction on the solid filter cake obtained in the step (2) and a metal carbonate solution with the mass concentration of 10-30% at 80-100 ℃ for 30-90 min to obtain slurry containing metal fluoride and slurry containing silica colloid, carrying out solid-liquid separation on the obtained slurry containing metal fluoride to obtain a filter cake containing metal fluoride and filtrate, and carrying out solid-liquid separation on the obtained slurry containing silica colloid to obtain a filter cake containing silica colloid and filtrate;
(4) returning one part of the filter cake containing the metal fluoride salt obtained in the step (3) to the step (2) for reaction, drying the other part of the filter cake, and reacting the dried part of the filter cake with sulfuric acid with the mass concentration of 98% to prepare anhydrous hydrogen fluoride, wherein the obtained anhydrous hydrogen fluoride is absorbed by the hydrofluoric acid solution obtained in the step (2); and (4) drying the filter cake containing the silica colloid obtained in the step (3) to obtain the white carbon black.
Compared with the prior art, the invention has the following beneficial effects:
(1) the method can recover not less than 90% of fluorine and silicon resources from the acidic fluorine-containing wastewater under mild conditions, and the fluorine resources are recovered in the form of hydrofluoric acid, can be recycled in the wet smelting process or sold as products, and have wide application; the silicon resource is recovered in the form of white carbon black and can be used as a raw material in the industries of rubber, plastics, papermaking, pesticides, coating, printing ink and the like;
(2) the method does not need to additionally add other raw materials or adopt cheap carbon alkali and concentrated sulfuric acid, and the concentrated sulfuric acid can also be taken from acid wastewater, so that the economy is good, and the process is easy to realize;
(3) in the whole process of the method, only one time of metal fluoride salt is added into the wastewater in the initial reaction, and the metal fluoride salt in the subsequent reaction process is directly generated in the reaction, so that the material consumption is greatly saved; no waste liquid is generated in the whole process, the method is more economic and environment-friendly, and the technical problems of reduction, harmlessness and recycling of the fluorine-containing waste water are solved;
(4) the method can greatly reduce the amount of acid wastewater neutralized by lime, reduces the amount of the acid wastewater by more than 70% compared with the prior art, and is easy to realize the comprehensive utilization of other valuable metal elements, thereby being expected to solve the technical problems of reduction, harmlessness and recycling of fluorine-containing wastewater.
Drawings
FIG. 1 is a process flow diagram of a method for recovering fluorine resources from acidic fluorine-containing wastewater according to the present invention.
Detailed Description
In order to better illustrate the present invention and facilitate the understanding of the technical solutions of the present invention, the present invention is further described in detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.
As shown in fig. 1, the invention provides a method for recovering fluorine resources in acidic fluorine-containing wastewater, which comprises the following steps:
a method for recovering fluorine resources in acidic fluorine-containing wastewater comprises the following steps:
(1) evaporating the acidic fluorine-containing wastewater to obtain an evaporation condensate and an evaporation concentrate;
(2) adding metal fluoride salt into the evaporation condensate obtained in the step (1) for reaction, carrying out solid-liquid separation on the slurry after the reaction to obtain a solid filter cake and filtrate, and rectifying and purifying the obtained filtrate to obtain a hydrofluoric acid solution;
(3) carrying out carbon-base decomposition reaction on the solid filter cake obtained in the step (2) and a metal carbonate solution to obtain slurry containing metal fluoride salt and slurry containing silica colloid, carrying out solid-liquid separation on the obtained slurry containing metal fluoride salt to obtain a filter cake containing metal fluoride salt and filtrate, and carrying out solid-liquid separation on the obtained slurry containing silica colloid to obtain a filter cake containing silica colloid and filtrate;
(4) returning one part of the filter cake containing the metal fluoride salt obtained in the step (3) to the step (2) for reaction, and drying the other part of the filter cake and reacting the dried filter cake with sulfuric acid to obtain anhydrous hydrogen fluoride; and (4) drying the filter cake containing the silica colloid obtained in the step (3) to obtain the white carbon black.
The following are typical but non-limiting examples of the invention:
example 1:
the embodiment provides a method for recovering fluorine resources in acidic fluorine-containing wastewater, wherein the acidic fluorine-containing wastewater is the fluorine-containing acidic wastewater of a certain niobium-tantalum hydrometallurgy enterprise, and the contents of main chemical components of the acidic fluorine-containing wastewater are shown in table 1:
table 1: chemical component content table in fluorine-containing acidic wastewater of certain niobium-tantalum hydrometallurgy enterprises
The method comprises the following steps:
(1) evaporating the acidic fluorine-containing wastewater at 100 ℃ and under the vacuum degree of 90kPa to obtain an evaporation condensate and an evaporation concentrate; the evaporated concentrated solution is cooled to obtain titanium-rich and iron-rich solid slag and a liquid phase taking concentrated sulfuric acid as a main component, the liquid phase is neutralized by lime milk for harmless treatment, and the liquid phase can also be used for preparing anhydrous hydrogen fluoride or be circularly used as a hydrometallurgy medium instead of the concentrated sulfuric acid;
(2) adding sodium fluoride solid into the evaporation condensate obtained in the step (1) for reaction, and performing solid-liquid separation on slurry after the reaction to obtain a solid filter cake and filtrate, wherein the molar ratio of the added sodium fluoride to silicon element in the evaporation condensate is 2.4:1 to obtain hydrofluoric acid with the concentration of 13 wt%, and then rectifying and purifying to obtain hydrofluoric acid solution with the concentration of 40 wt%;
(3) carrying out carbon-base decomposition reaction on the solid filter cake obtained in the step (2) and a sodium carbonate solution at 100 ℃ for 1h to obtain slurry containing solid sodium fluoride and slurry containing silica colloid, carrying out solid-liquid separation on the obtained slurry containing sodium fluoride to obtain a filter cake containing solid sodium fluoride and filtrate, and carrying out solid-liquid separation on the obtained slurry containing silica colloid to obtain a filter cake containing silica colloid and filtrate;
(4) returning one part of the filter cake containing the solid sodium fluoride obtained in the step (3) to the step (2) for reaction, drying the other part of the filter cake, and reacting the dried part of the filter cake with sulfuric acid to obtain anhydrous hydrogen fluoride, wherein the obtained anhydrous hydrogen fluoride is absorbed by the hydrofluoric acid solution obtained in the step (2) to obtain a hydrofluoric acid product with the concentration of 59 wt%; and (4) drying the filter cake containing the silica colloid obtained in the step (3) to obtain the white carbon black.
In the invention, the recovery rates of fluorine and silicon in the acidic fluorine-containing wastewater are 91.9% and 92.4% respectively.
Example 2:
the embodiment provides a method for recovering fluorine resources in acidic fluorine-containing wastewater, wherein the acidic fluorine-containing wastewater is the fluorine-containing acidic wastewater of a certain niobium-tantalum hydrometallurgy enterprise, and the content of the main chemical components of the acidic fluorine-containing wastewater is the same as that in the embodiment 1.
The method comprises the following steps:
(1) evaporating the acidic fluorine-containing wastewater at 180 ℃ under atmospheric pressure to obtain an evaporation condensate and an evaporation concentrate; the evaporated concentrated solution is cooled to obtain titanium-rich and iron-rich solid slag and a liquid phase taking concentrated sulfuric acid as a main component, the liquid phase is neutralized by lime milk for harmless treatment, and the liquid phase can also be used for preparing anhydrous hydrogen fluoride or be circularly used as a hydrometallurgy medium instead of the concentrated sulfuric acid;
(2) adding sodium fluoride solid into the evaporation condensate obtained in the step (1) for reaction, and performing solid-liquid separation on slurry after the reaction to obtain a solid filter cake and filtrate, wherein the molar ratio of the added sodium fluoride to silicon element in the evaporation condensate is 2:1 to obtain hydrofluoric acid with the concentration of 6 wt%, and then rectifying and purifying to obtain a hydrofluoric acid solution with the concentration of 20 wt%;
(3) carrying out carbon-base decomposition reaction on the solid filter cake obtained in the step (2) and a sodium carbonate solution at 50 ℃ for 2h to obtain slurry containing solid sodium fluoride and slurry containing silica colloid, carrying out solid-liquid separation on the obtained slurry containing sodium fluoride to obtain a filter cake containing solid sodium fluoride and filtrate, and carrying out solid-liquid separation on the obtained slurry containing silica colloid to obtain a filter cake containing silica colloid and filtrate;
(4) returning one part of the filter cake containing the solid sodium fluoride obtained in the step (3) to the step (2) for reaction, drying the other part of the filter cake, and reacting the dried part of the filter cake with sulfuric acid to obtain anhydrous hydrogen fluoride, wherein the obtained anhydrous hydrogen fluoride is absorbed by the hydrofluoric acid solution obtained in the step (2) to obtain a hydrofluoric acid product with the concentration of 41 wt%; and (4) drying the filter cake containing the silica colloid obtained in the step (3) to obtain the white carbon black.
In the invention, the recovery rates of fluorine and silicon in the acidic fluorine-containing wastewater are respectively 94.3% and 95.8%.
Example 3:
the embodiment provides a method for recovering fluorine resources in acidic fluorine-containing wastewater, wherein the acidic fluorine-containing wastewater is the fluorine-containing acidic wastewater of a certain niobium-tantalum hydrometallurgy enterprise, and the content of the main chemical components of the acidic fluorine-containing wastewater is the same as that in the embodiment 1.
The method is the same as that in the example 1 except that the evaporation temperature in the step (1) is 80 ℃, the evaporation vacuum degree is 60kPa, the molar ratio of the sodium fluoride added in the step (2) to the silicon element in the evaporation condensate is 1.9:1, the temperature of the decomposition reaction of the carbon base in the step (3) is 110 ℃, and the reaction time is 0.5 h.
In this example, the recovery rates of fluorine and silicon in the acidic fluorine-containing wastewater were 90.3% and 91.6%, respectively.
Example 4:
the embodiment provides a method for recovering fluorine resources in acidic fluorine-containing wastewater, wherein the acidic fluorine-containing wastewater is the fluorine-containing acidic wastewater of a certain niobium-tantalum hydrometallurgy enterprise, and the content of the main chemical components of the acidic fluorine-containing wastewater is the same as that in the embodiment 1.
The amounts of the materials and the preparation method were the same as in example 1 except that the metal fluoride salt was potassium fluoride and the metal carbonate was potassium carbonate.
In this example, the recovery rates of fluorine and silicon in the acidic fluorine-containing wastewater were 95.2% and 96.7%, respectively.
The results of the examples 1-4 show that the method can recover not less than 90% of fluorine and silicon resources from the acidic fluorine-containing wastewater under mild conditions, the fluorine resources are recovered in the form of hydrofluoric acid, and can be recycled in the wet smelting process or sold as products, so that the method has wide application; the silicon resource is recovered in the form of white carbon black, and can be used as a raw material in industries such as rubber, plastics, papermaking, pesticides, coating, printing ink and the like.
Meanwhile, other raw materials do not need to be additionally added or cheap carbon alkali and concentrated sulfuric acid are adopted, and the concentrated sulfuric acid can also be obtained from acid wastewater, so that the method is good in economy and easy to realize; in the whole process, only one time of metal fluoride salt is added to the wastewater in the initial reaction, and the metal fluoride salt in the subsequent reaction process is directly generated in the reaction, so that the material consumption is greatly saved; and no waste liquid is generated in the whole process, so that the method is more economic and environment-friendly, and the technical problems of reduction, harmlessness and recycling of the fluorine-containing wastewater are solved.
In addition, the method can greatly reduce the amount of acid wastewater neutralized by lime, so that the amount of the acid wastewater is reduced by more than 70% compared with the prior art, and the comprehensive utilization of other valuable metal elements is easy to realize, so that the technical problems of reduction, harmlessness and recycling of fluorine-containing wastewater are expected to be solved.
The applicant states that the present invention is illustrated by the above examples to show the detailed process equipment and process flow of the present invention, but the present invention is not limited to the above detailed process equipment and process flow, i.e. it does not mean that the present invention must rely on the above detailed process equipment and process flow to be implemented. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (24)
1. A method for recovering fluorine resources in acidic fluorine-containing wastewater is characterized by comprising the following steps:
(1) evaporating the acidic fluorine-containing wastewater to obtain an evaporation condensate and an evaporation concentrate;
(2) adding metal fluoride salt into the evaporation condensate obtained in the step (1) for reaction, carrying out solid-liquid separation on the slurry after the reaction to obtain a solid filter cake and filtrate, and rectifying and purifying the obtained filtrate to obtain a hydrofluoric acid solution;
(3) carrying out carbon-base decomposition reaction on the solid filter cake obtained in the step (2) and a metal carbonate solution to obtain slurry containing metal fluoride salt and slurry containing silica colloid, carrying out solid-liquid separation on the obtained slurry containing metal fluoride salt to obtain a filter cake containing metal fluoride salt and filtrate, and carrying out solid-liquid separation on the obtained slurry containing silica colloid to obtain a filter cake containing silica colloid and filtrate;
(4) returning one part of the filter cake containing the metal fluoride salt obtained in the step (3) to the step (2) for reaction, and drying the other part of the filter cake and reacting the dried filter cake with sulfuric acid to obtain anhydrous hydrogen fluoride; drying the filter cake containing the silica colloid obtained in the step (3) to prepare white carbon black;
the acidic fluorine-containing wastewater in the step (1) is acidic fluorine-containing wastewater in niobium-tantalum hydrometallurgy industry.
2. The recovery method according to claim 1, wherein the acid concentration in the acidic fluorine-containing wastewater in step (1) is > 10N.
3. The recycling method according to claim 1, wherein the evaporation temperature of the evaporation in the step (1) is 80 to 180 ℃.
4. The recycling method according to claim 3, wherein the evaporation temperature of the evaporation in the step (1) is 110 to 160 ℃.
5. The recycling method according to claim 1, wherein the degree of vacuum of the evaporation in the step (1) is 0 to 90 kPa.
6. The recycling method according to claim 5, wherein the degree of vacuum of the evaporation in the step (1) is 10 to 70 kPa.
7. The recovery method according to claim 1, characterized in that the evaporation concentrated solution in the step (1) is sequentially cooled, recovered and extracted with valuable metal elements, neutralized with lime milk and discharged.
8. The recovery method according to claim 1, wherein the metal fluoride salt in the step (2) is sodium fluoride and/or potassium fluoride.
9. The recovery method according to claim 8, wherein the metal fluoride salt in the step (2) is sodium fluoride.
10. The recovery method according to claim 1, wherein the metal fluoride salt is added in the step (2) in a solid and/or liquid form.
11. The recovery method according to claim 1, wherein the molar ratio of the metal fluoride salt added in the step (2) to the silicon element in the evaporation condensate is (1.9-2.4): 1.
12. The recovery method according to claim 11, wherein the molar ratio of the metal fluoride salt added in the step (2) to the silicon element in the evaporation condensate is (2.0-2.3): 1.
13. The recovery method according to claim 1, wherein the reaction temperature of the reaction in the step (2) is 10 to 90 ℃.
14. The recovery method according to claim 1, wherein the hydrofluoric acid solution in the step (2) has a mass concentration of 5 to 20%.
15. The recovery method according to claim 1, wherein the metal carbonate in the step (3) is sodium carbonate and/or potassium carbonate.
16. The recycling method according to claim 1, wherein the mass concentration of the metal carbonate solution in the step (3) is 10 to 30%.
17. The recovery method according to claim 1, wherein the reaction temperature of the carbon-base decomposition reaction in the step (3) is 50 to 110 ℃.
18. The recovery method according to claim 17, wherein the reaction temperature of the carbon-base decomposition reaction in the step (3) is 80 to 100 ℃.
19. The recovery method according to claim 1, wherein the reaction time of the carbon-base decomposition reaction in the step (3) is 0.5 to 2 hours.
20. The recovery method according to claim 19, wherein the reaction time of the carbon-base decomposition reaction in the step (3) is 30 to 90 min.
21. The recovery method according to claim 1, wherein the filtrate obtained in the step (3) is returned to participate in the carbon-alkali decomposition reaction.
22. The recovery method according to claim 1, wherein the sulfuric acid used in the step (4) has a mass concentration of 98%.
23. The recovery method according to claim 1, wherein the anhydrous hydrogen fluoride obtained in the step (4) is absorbed by the hydrofluoric acid solution obtained in the step (2).
24. A recovery process according to any of claims 1-23, characterized in that the process comprises the steps of:
(1) evaporating the acidic fluorine-containing wastewater at the temperature of 110-160 ℃ and the vacuum degree of 10-70 kPa to obtain an evaporation condensate and an evaporation concentrate;
(2) adding sodium fluoride into the evaporation condensate obtained in the step (1) to react at 10-90 ℃, performing solid-liquid separation on the slurry after the reaction to obtain a solid filter cake and a filtrate, wherein the molar ratio of the added sodium fluoride to silicon element in the evaporation condensate is (2.0-2.3): 1, and rectifying and purifying the obtained filtrate to obtain a hydrofluoric acid solution with the mass concentration of 5-20%;
(3) carrying out carbon-base decomposition reaction on the solid filter cake obtained in the step (2) and a metal carbonate solution with the mass concentration of 10-30% at 80-100 ℃ for 30-90 min to obtain slurry containing metal fluoride and slurry containing silica colloid, carrying out solid-liquid separation on the obtained slurry containing metal fluoride to obtain a filter cake containing metal fluoride and filtrate, and carrying out solid-liquid separation on the obtained slurry containing silica colloid to obtain a filter cake containing silica colloid and filtrate;
(4) reacting a part of the filter cake containing the metal fluoride salt obtained in the step (3) in the step (2), drying the other part of the filter cake, and reacting the dried part of the filter cake with sulfuric acid with the mass concentration of 98% to obtain anhydrous hydrogen fluoride, wherein the obtained anhydrous hydrogen fluoride is absorbed by the hydrofluoric acid solution obtained in the step (2); and (4) drying the filter cake containing the silica colloid obtained in the step (3) to obtain the white carbon black.
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| JPH0615266A (en) * | 1992-07-02 | 1994-01-25 | Japan Organo Co Ltd | Concentration of fluorine-containing waste water |
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| CN105461138A (en) * | 2015-12-28 | 2016-04-06 | 中南大学 | Method for recycling sulfuric acid and hydrochloric acid from smelting wastewater and realizing fluorine open circuit |
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| JPH0615266A (en) * | 1992-07-02 | 1994-01-25 | Japan Organo Co Ltd | Concentration of fluorine-containing waste water |
| CN1504419A (en) * | 2002-11-28 | 2004-06-16 | �G�ֻ�е��������˾ | Hydrofluoric acid wastewater treatment method and device |
| CN102502500A (en) * | 2011-11-07 | 2012-06-20 | 韩扶军 | Device for producing hydrogen chloride by resolving hydrochloric acid |
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