Treatment method for extracting ammonium fluoride from fluorine-containing waste liquid

Abstract

The invention discloses a treatment method for extracting ammonium fluoride from fluorine-containing waste liquid, which comprises the following steps: pretreating the fluorine-containing waste liquid: detecting the pH value, fluorine ion concentration and other impurity components of the fluorine-containing waste liquid, adjusting the pH value of the fluorine-containing waste liquid, and removing most of precipitates in the fluorine-containing waste liquid; reacting and precipitating: adding an ammonium sulfate solution into the pretreated fluorine-containing waste liquid, and reacting to generate ammonium fluoride and calcium sulfate precipitates; filtering and separating: after the reaction is finished, separating the calcium sulfate precipitate from the solution containing the ammonium fluoride through filtering equipment, washing the filtered calcium sulfate precipitate for multiple times, and merging the washing liquid into the solution containing the ammonium fluoride to improve the recovery rate of the ammonium fluoride; impurity removal and refinement: adding a proper amount of barium carbonate solution into the solution containing ammonium fluoride to remove sulfate ions in the solution; according to the method, the fluorine element in the waste liquid can be converted into an ammonium fluoride product with economic value, and recycling of resources is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of ammonium fluoride treatment, and specifically to a treatment method for extracting ammonium fluoride from fluorine-containing waste liquid. Background Art

[0002] In many industrial processes such as chemical production, electronic chip manufacturing, and metallurgical surface treatment, a large amount of fluorine-containing waste liquid is generated. The concentration of fluoride ions in these waste liquids is relatively high. If directly discharged, it will cause serious pollution to the ecological environment such as soil and water bodies, and endanger the growth of animals and plants and human health. At present, the treatment method of fluorine-containing waste liquid is mostly simple neutralization precipitation followed by discharge. This treatment method not only cannot recover fluorine resources but may also cause secondary pollution. Ammonium fluoride, as an important chemical raw material, has wide applications in the fields of medicine, pesticides, electronics, etc.

[0003] Therefore, it is of great practical significance to propose a method for extracting ammonium fluoride from fluorine-containing waste liquid. Summary of the Invention

[0004] The purpose of the present invention is to provide a treatment method for extracting ammonium fluoride from fluorine-containing waste liquid, which is characterized in that the treatment method includes:

[0005] Step 1: Pretreat the fluorine-containing waste liquid: Detect the pH value, fluoride ion concentration, and other impurity components of the fluorine-containing waste liquid. For the fluorine-containing waste liquid with strong acidity, add an appropriate amount of calcium hydroxide or calcium oxide for preliminary neutralization to increase the pH value of the waste liquid to 6 - 7, and at the same time generate calcium fluoride precipitation. Filter out most of the calcium fluoride precipitation to reduce the burden of subsequent treatment;

[0006] Step 2: React and precipitate: Add ammonium sulfate solution to the pretreated fluorine-containing waste liquid to react to form ammonium fluoride and calcium sulfate precipitation. The addition amount of ammonium sulfate is calculated according to the content of fluoride ions in the waste liquid, and generally added in an excess of 5% - 10% according to the stoichiometric ratio to ensure the full reaction of fluoride ions. The reaction temperature is controlled at 40 - 50 °C, and the reaction is stirred for 1.5 - 2.5 hours to promote the full progress of the reaction;

[0007] Step 3: Filter and separate: After the reaction is completed, separate the calcium sulfate precipitation from the solution containing ammonium fluoride through a filtering device, wash the filtered calcium sulfate precipitation multiple times, and merge the washing liquid into the solution containing ammonium fluoride to improve the recovery rate of ammonium fluoride;

[0008] Step 4: Remove impurities and refine: Add an appropriate amount of barium carbonate solution to the solution containing ammonium fluoride to remove sulfate ions in the solution, generate barium sulfate precipitation, filter again to remove barium sulfate precipitation, and then add an appropriate amount of activated carbon for adsorption and decolorization to further remove organic impurities and pigments in the solution and improve the purity of ammonium fluoride products;

[0009] Step 5: Crystallization and drying: Evaporate and concentrate the ammonium fluoride solution after impurity removal and refining. When the solution reaches a supersaturated state, stop heating and allow it to cool naturally for crystallization. After crystallization is complete, separate the ammonium fluoride crystals from the mother liquor by centrifugation. The mother liquor can be returned to the reaction precipitation step for recycling to improve the utilization rate of fluorine resources. Dry the separated ammonium fluoride crystals in a drying oven at 60 - 70 °C until constant weight to obtain ammonium fluoride products;

[0010] Step 6: Product detection: Conduct quality detection on the obtained ammonium fluoride products. The quality detection includes the detection of the purity, moisture content, and heavy metal content of ammonium fluoride. Among them, acid-base titration is used for purity detection, the Karl Fischer method is used for moisture content detection, and atomic absorption spectrometry is used for heavy metal content detection.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention utilizes chemical precipitation, acid-base neutralization, and crystallization principles to separate and extract ammonium fluoride from fluorine-containing waste liquid, effectively treating the fluorine-containing waste liquid, reducing the environmental pollution caused by fluoride ions, and at the same time converting the fluorine element in the waste liquid into ammonium fluoride products with economic value to achieve the recycling and reuse of resources. Description of the Drawings

[0012] Figure 1 is the process flow chart of the present invention;

[0013] Figure 2 is the schematic diagram of the product quality and application effect of the present invention under different reaction conditions; Detailed Embodiments

[0014] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0015] As shown in the attached Figure 1 figures, a treatment method for extracting ammonium fluoride from fluorine-containing waste liquid provided by the present invention includes:

[0016] Step 1: Pretreat the fluorine-containing waste liquid: Detect the pH value, fluoride ion concentration, and other impurity components of the fluorine-containing waste liquid. For the fluorine-containing waste liquid with strong acidity, add an appropriate amount of calcium hydroxide or calcium oxide for preliminary neutralization to increase the pH value of the waste liquid to 6 - 7, and at the same time generate calcium fluoride precipitation. Filter out most of the calcium fluoride precipitation to reduce the burden of subsequent treatment;

[0017] Step 2: Reaction precipitation: Add ammonium sulfate solution to the pretreated fluorine-containing waste liquid to react and form ammonium fluoride and calcium sulfate precipitate. The addition amount of ammonium sulfate is calculated according to the fluorine ion content in the waste liquid, and generally 5%-10% is added in excess according to the stoichiometric ratio to ensure the full reaction of fluorine ions. The reaction temperature is controlled at 40-50 °C, and the reaction is stirred for 1.5-2.5 hours to promote the full progress of the reaction;

[0018] Step 3: Filtration separation: After the reaction is completed, separate the calcium sulfate precipitate from the solution containing ammonium fluoride through a filtration device, wash the filtered calcium sulfate precipitate several times with water, and merge the washing liquid into the solution containing ammonium fluoride to improve the recovery rate of ammonium fluoride;

[0019] Step 4: Impurity removal and purification: Add an appropriate amount of barium carbonate solution to the solution containing ammonium fluoride to remove sulfate ions in the solution and form barium sulfate precipitate. Filter again to remove the barium sulfate precipitate, and then add an appropriate amount of activated carbon for adsorption and decolorization to further remove organic impurities and pigments in the solution and improve the purity of ammonium fluoride products;

[0020] Step 5: Crystallization and drying: Evaporate and concentrate the ammonium fluoride solution after impurity removal and purification. When the solution reaches a supersaturated state, stop heating and cool it naturally to crystallize. After crystallization is completed, separate the ammonium fluoride crystals from the mother liquor by centrifugation. The mother liquor can be returned to the reaction precipitation step for recycling to improve the utilization rate of fluorine resources. Dry the separated ammonium fluoride crystals in a drying oven at 60-70 °C to constant weight to obtain ammonium fluoride products;

[0021] Step 6: Product detection: Conduct quality detection on the obtained ammonium fluoride products. The quality detection includes the detection of the purity, moisture content, and heavy metal content of ammonium fluoride. Among them, the purity detection uses the acid-base titration method, the moisture content detection uses the Karl Fischer method, and the heavy metal content detection uses the atomic absorption spectrometry method.

[0022] Example 1:

[0023] Verification:

[0024] Take a certain amount of the prepared ammonium fluoride product and conduct the following verification experiments:

[0025] 1. Purity verification: Accurately weigh 1-2 g of the above-obtained ammonium fluoride product, dissolve it in an appropriate amount of deionized water, and titrate it with a standard sodium hydroxide solution. Calculate the purity of ammonium fluoride according to the volume of the consumed sodium hydroxide solution. If the purity reaches more than 98%, it indicates that the product purity meets the requirements; if the purity is lower than 98%, the reasons need to be analyzed and the extraction process needs to be adjusted;

[0026] 2. Stability verification: Place the ammonium fluoride product at normal temperature and pressure and observe whether there is deliquescence or decomposition. If there is no obvious change within one week, it indicates that the product has good stability. If deliquescence or decomposition occurs, the drying process needs to be optimized or the product packaging needs to be improved.

[0027] 3. Application performance verification: Apply the ammonium fluoride product to relevant chemical production processes, such as as a synthetic raw material for pharmaceutical intermediates, and observe the reaction effect and product quality. If the reaction proceeds smoothly and the obtained product quality meets the requirements, it indicates that the extracted ammonium fluoride product has good performance and can meet the actual application needs.

[0028] As shown in the Figure 2 appendix, the purity and application are verified by three methods.

[0029] Method 1: The ammonium sulfate is in excess by 5%, the reaction temperature is 40 °C, and the reaction time is 1.5 hours.

[0030] Method 2: The ammonium sulfate is in excess by 8%, the reaction temperature is 45 °C, and the reaction time is 2 hours.

[0031] Method 3: The ammonium sulfate is in excess by 10%, the reaction temperature is 50 °C, and the reaction time is 2.5 hours.

[0032] Conclusion:

[0033] 1. By adopting the process route of ammonium sulfate precipitation, impurity removal and refining, and crystallization drying, under the conditions that the ammonium sulfate is in excess by 8%, the reaction temperature is 45 °C, and the reaction time is 2 hours, ammonium fluoride products with high purity and stable quality can be extracted from fluorine-containing waste liquid.

[0034] 2. During the extraction process, by strictly controlling the reaction conditions and impurity removal steps, the impurity content in the product can be effectively reduced and the product quality can be improved.

[0035] 3. This extraction method can realize the resource utilization of fluorine-containing waste liquid, reduce fluorine pollution, and has good environmental and economic benefits. At the same time, the obtained ammonium fluoride products can meet the requirements of relevant industrial applications.

[0036] Using the technical solution described in the present invention, or those skilled in the art designing similar technical solutions inspired by the technical solution of the present invention and achieving the above technical effects shall fall within the protection scope of the present invention.

Claims

1. A treatment method for extracting ammonium fluoride from fluorine-containing waste liquid, characterized in that: The treatment method includes: Step 1: Pretreat the fluorine-containing waste liquid: Detect the pH value, fluoride ion concentration, and other impurity components of the fluorine-containing waste liquid, adjust the pH value of the fluorine-containing waste liquid, and remove most of the precipitates in the fluorine-containing waste liquid; Step 2: React and precipitate: Add ammonium sulfate solution to the pretreated fluorine-containing waste liquid to react to form ammonium fluoride and calcium sulfate precipitate; Step 3: Filter and separate: After the reaction is completed, separate the calcium sulfate precipitate from the solution containing ammonium fluoride through a filtering device, wash the filtered calcium sulfate precipitate multiple times, and merge the washing liquid into the solution containing ammonium fluoride to improve the recovery rate of ammonium fluoride; Step 4: Remove impurities and refine: Add an appropriate amount of barium carbonate solution to the solution containing ammonium fluoride to remove sulfate ions in the solution, form barium sulfate precipitate, filter again to remove the barium sulfate precipitate, and then add an appropriate amount of activated carbon for adsorption and decolorization to further remove organic impurities and pigments in the solution and improve the purity of the ammonium fluoride product; Step 5: Crystallize and dry: Evaporate and concentrate the ammonium fluoride solution after impurity removal and refinement. When the solution reaches a supersaturated state, stop heating and cool it naturally to crystallize. After crystallization is completed, separate the ammonium fluoride crystals from the mother liquor through centrifugal separation. The mother liquor can be returned to the reaction precipitation step for recycling to improve the utilization rate of fluorine resources. Dry the separated ammonium fluoride crystals in a drying oven until they reach a constant weight to obtain ammonium fluoride products; Step 6: Product detection: Conduct quality detection on the obtained ammonium fluoride products.

2. The treatment method for extracting ammonium fluoride from fluorine-containing waste liquid according to claim 1, characterized in that: In Step 1, for the fluorine-containing waste liquid with strong acidity, add an appropriate amount of calcium hydroxide or calcium oxide for preliminary neutralization to raise the pH value of the waste liquid to 6-7, and at the same time generate calcium fluoride precipitate. Filter to remove most of the calcium fluoride precipitate to reduce the burden of subsequent treatment.

3. The treatment method for extracting ammonium fluoride from fluorine-containing waste liquid according to claim 1, characterized in that: The addition amount of ammonium sulfate in Step 2 is calculated according to the content of fluoride ions in the waste liquid, and generally added in an excess of 5%-10% according to the stoichiometric ratio to ensure full reaction of fluoride ions. The reaction temperature is controlled at 40-50°C, and the stirring reaction is carried out for 1.5-2.5 hours to promote full reaction.

4. The treatment method for extracting ammonium fluoride from fluorine-containing waste liquid according to claim 1, characterized in that: In Step 5, the drying oven dries the ammonium fluoride crystals at a temperature of 60-70°C.

5. The treatment method for extracting ammonium fluoride from fluorine-containing waste liquid according to claim 1, wherein: The quality detection in Step 6 includes the detection of the purity, moisture content, and heavy metal content of ammonium fluoride. Among them, the purity detection uses the acid-base titration method, the moisture content detection uses the Karl Fischer method, and the heavy metal content detection uses the atomic absorption spectrometry method.

Images