Treatment method for removing fluorine from high-purity quartz sand pickling sewage

Abstract

The invention discloses a treatment method for removing fluorine from high-purity quartz sand pickling sewage, which comprises the following steps: S1, primary precipitation: adjusting the pH value of a silicon fluoride-containing waste liquid to 8-8.5 by using calcium hydroxide, adding a fluorine removal agent F1 for aeration, adding PAC and PAM for aeration, and precipitating and flocculating; s2, secondary ion exchange: feeding the clarified liquid into an ion exchange resin pool for ion exchange; s3, third-stage filtration: sequentially feeding the exchange liquid into a sand filter tank, an activated carbon filter tank and a bag filter for filtration. According to the method, three-stage fluorine removal including first-stage precipitation, second-stage ion exchange and third-stage filtration is adopted, the fluorine ion removal rate is remarkably increased and reaches 99.9% or above, the fluorine content in water is smaller than 0.3 mg / L, the treatment method is simple, and the effect is excellent.

Description

Technical Field

[0001] The invention relates to a method for removing fluorine from high-purity quartz sand pickling wastewater, belonging to the technical field of wastewater. Background Art

[0002] High-purity quartz sand is purified through processes such as quartz stone sorting, roasting / water quenching, crushing / screening, magnetic separation, pickling, flotation, drying, and cooling. Among them, pickling is the acidification of quartz stone (silicon dioxide) with hydrochloric acid (hydrogen chloride) and hydrofluoric acid (hydrogen fluoride) by soaking in a reactor. Therefore, pickling will produce a large amount of waste liquid containing silicon fluoride. If the waste liquid containing silicon fluoride is not handled properly, the fluorine pollution of the water body will not only seriously affect human health, but also cause damage to the ecosystem.

[0003] In the prior art, there are two methods for treating fluoride pollutants in water bodies: precipitation method and adsorption method: precipitation method: for wastewater with higher fluoride content, fluoride ions and calcium ions can be added with lime to form calcium fluoride precipitates for removal; for wastewater with lower fluoride content, fluoride ions can be added with iron salts and aluminum salts as coagulants to form flocculants for precipitation removal, but the fluoride content after treatment still exceeds the standard, the removal efficiency is low, and the fluoride removal rate is low; adsorption method, fluoride in wastewater is removed by adsorption by adsorbents, and commonly used adsorbents include fly ash, impregnation activated alumina, solid industrial waste red mud, etc., but the adsorption capacity of the adsorbent is affected by the fluoride concentration, and the adsorption capacity decreases significantly with the decrease of fluoride concentration, and the fluoride removal efficiency is low. Summary of the invention

[0004] In view of at least one problem existing in the above-mentioned prior art, the present invention provides a method for defluoridating high-purity quartz sand pickling wastewater, which adopts a three-stage defluoridation of primary precipitation-secondary ion exchange-tertiary filtration, and significantly improves the removal rate of fluoride ions to more than 99.9%. The fluoride content in the water quality is less than 0.3 mg / L. The treatment method is simple and the effect is excellent.

[0005] In order to achieve the above object, the present invention adopts the following technical scheme: a method for removing fluorine from high-purity quartz sand pickling wastewater, comprising the following steps:

[0006] S1, primary precipitation

[0007] S1.1 Take the waste liquid containing silicon fluoride from the wastewater collection tank and place it in the regulating tank to determine the fluorine content in the waste liquid;

[0008] S1.2 adding calcium hydroxide to the waste liquid, adjusting the pH to 8-8.5, and then adding a defluorinating agent F1, the amount of which is calculated based on the initial fluorine content in the waste liquid, and turning on a magnetic suspension blower for aeration for 30-50 minutes; the defluorinating agent F1 includes sodium hydroxide, stannous chloride, polyethylene glycol, auxiliary additives and water;

[0009] S1.3 Add polyaluminium chloride and polyacrylamide to the wastewater, and aerate it with a Roots blower to make the tiny particles and colloids in the wastewater condense into larger flocs, and then separate them in a sedimentation and flocculation tank to produce a clear liquid with defluorination;

[0010] S2, Secondary Ion Exchange

[0011] The clarified liquid from the first-stage defluorination is sent to an ion exchange resin pool for ion exchange, with the flow rate controlled at 5 to 20 m / h and the contact time at 20 to 60 min to produce a defluorinated exchange liquid;

[0012] S3, three-stage filtration

[0013] The exchange liquid from the secondary defluorination process is first sent to a sand filter tank for filtration at a flow rate of 5 to 10 m / h to further remove suspended particles and residual flocs in the water and improve the water quality. It is then sent to an activated carbon filter tank for filtration to further adsorb organic matter, residual chlorine, etc. in the water and further purify the water quality. Finally, it is sent to a bag filter for filtration until the water quality reaches the standard for domestic water and is discharged into a pool.

[0014] Preferably, the calculation method according to the fluorine content in the waste liquid is: the input amount of the defluorination agent F1 = correlation coefficient × the weight of fluoride ions in the waste liquid; the correlation coefficient is 17.0 to 17.5.

[0015] In addition, it should be noted that the weight of fluoride ions in the waste liquid = C0×V0, wherein C0 represents the fluorine content in the waste liquid, mg / L; V0 represents the volume of the waste liquid, L.

[0016] Preferably, the defluorination agent F1 comprises the following raw materials, calculated by mass fraction: 15-25% sodium hydroxide, 0.5-2% stannous chloride, 10-15% polyethylene glycol, 5-7% auxiliary additives and the rest water.

[0017] Preferably, the auxiliary additive is ammonium sulfate, or ammonium sulfate and phosphate additives.

[0018] Preferably, the auxiliary additives are ammonium sulfate and phosphate additives, and the mass ratio of the ammonium sulfate to the phosphate additives is 4:(1-2).

[0019] Preferably, the amount of PAC added is 0.4-0.45% of the amount of defluorination agent F1 added.

[0020] Preferably, the amount of PAM added is 0.1-0.15% of the amount of defluorination agent F1 added.

[0021] Preferably, the rotation speed of the Roots blower for aeration is 100-200 r / min.

[0022] Preferably, the ion exchange resin in the ion exchange resin pool is a strongly basic anion exchange resin having high selectivity and adsorption capacity for fluoride ions, such as strongly basic anion exchange resin IRA900, strongly basic anion exchange resin D201 。

[0023] Preferably, the resin filling amount in the ion exchange resin pool is 10-30% of the treated water volume, for example, when the treated water volume is 10 m3 / h, the resin filling amount is 1-3 m3.

[0024] Preferably, after the ion exchange resin is saturated with adsorption, a regeneration agent is used for regeneration treatment, the regeneration agent is a mixed solution of sodium hydroxide and sodium chloride, the regeneration agent concentration is 5-10%, the regeneration flow rate is 2-4 m / h, and the regeneration time is 30-60 min; in addition, the regeneration cycle is determined according to the adsorption saturation of the ion exchange resin.

[0025] Preferably, the sand filter tank uses quartz sand as filter material, with a particle size of 0.5 to 1.2 mm and a filter layer thickness of 700 to 1000 mm.

[0026] Preferably, the activated carbon filter tank uses activated carbon as filter material, the particle size is 2 to 4 mm, and the filter layer thickness is 500 to 800 mm.

[0027] Beneficial effects of the present invention:

[0028] 1. The method for removing fluorine from high-purity quartz sand pickling wastewater of the present invention adopts a three-stage defluorination process of primary precipitation-secondary ion exchange-tertiary filtration, which significantly improves the removal rate of fluoride ions to more than 99.9%, and the fluoride content in the water quality is less than 0.3 mg / L. The treatment method is simple and the effect is excellent.

[0029] 2. The method for removing fluorine from pickling wastewater of the present invention adopts a defluorinating agent F1. After primary precipitation, the fluorine content in the waste liquid is less than 5 mg / L, and the fluorine ion removal rate reaches more than 99.5%. On the one hand, the discharge standard of the fluorine content in the waste water is met, and on the other hand, it is helpful to the stability of adsorption and replacement during the secondary ion exchange treatment. After the secondary ion exchange, the fluorine content in the waste liquid is less than 0.5 mg / L, the fluorine ion removal rate of the secondary ion exchange reaches more than 99.0%, and the total fluorine ion removal rate reaches more than 99.9%, achieving the standard of fluorine content in domestic water.

[0030] 3. The defluoridation agent F1 of the treatment method for defluoridation of pickling wastewater of the present invention is composed of sodium hydroxide, stannous chloride, polyethylene glycol, auxiliary additives and water. The sodium hydroxide provides an alkaline environment, which is conducive to the precipitation of fluoride. Stannous chloride is used as a reducing agent to convert fluoride into gaseous nitrogen trifluoride, thereby effectively removing fluorine. Polyethylene glycol plays a role in adjusting the solvent performance. DETAILED DESCRIPTION

[0031] The following is a clear and complete description of the technical solutions in the implementation of the present invention. 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 ordinary technicians in the field without making creative work are within the scope of protection of the present invention. If the specific conditions are not specified in the embodiments, they are carried out according to the normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents, instruments, and components used, they are all conventional products that can be purchased commercially.

[0032] Example 1

[0033] S1, primary precipitation

[0034] S1.1 Take 40L of waste liquid containing silicon fluoride from the wastewater collection tank and put it into the regulating tank. The fluorine content in the waste liquid is measured to be 1634mg / L;

[0035] S1.2 Add calcium hydroxide to the waste liquid to adjust the pH to 8, then add 1143.8g of defluoridation agent F1, and start the magnetic suspension blower for aeration for 50 minutes;

[0036] Defluorinating agent F1, by mass fraction, includes the following raw materials: 15% sodium hydroxide, 0.5% stannous chloride, 10% polyethylene glycol, 5% ammonium sulfate, and the rest is water;

[0037] S1.3 Add 4.58g PAC and 1.45g PAM to the wastewater, and aerate it at 150r / min with a Roots blower to make the tiny particles and colloids in the wastewater condense into larger flocs, and then separate them in a sedimentation and flocculation tank. The fluorine content of the clarified wastewater after defluorination is measured to be 4.5mg / L.

[0038] S2, Secondary Ion Exchange

[0039] The clarified liquid in the first-stage defluorination process is sent to an ion exchange resin pool using alkaline anion exchange resin IRA900 for ion exchange. The resin filling amount in the ion exchange resin pool is 20% of the treated water volume. For example, if the treated water volume is 10m / h, the resin filling amount is 2m, the flow rate is controlled to be 12.5m / h, the contact time is 40min, and the fluorine content of the defluorinated exchange liquid is measured to be 0.43mg / L.

[0040] In addition, the regeneration cycle is determined according to the adsorption saturation of the ion exchange resin. After the ion exchange resin is adsorbed to saturation, a regeneration agent is used for regeneration. The regeneration agent is a mixed solution of sodium hydroxide and sodium chloride. The concentration of the regeneration agent is 8%, the regeneration flow rate is 3m / h, and the regeneration time is 45min.

[0041] S3, three-stage filtration

[0042] The exchange liquid removed from the secondary defluorination process is first sent to a sand filter tank with quartz sand of 0.5-1.2mm in size as filter material and a filter layer thickness of 850mm for filtration at a flow rate of 7.5m / h to further remove suspended particles and residual flocs in the water and improve the water quality. It is then sent to an activated carbon filter tank with activated carbon of 2-4mm in size as filter material and a filter layer thickness of 650mm for filtration to further adsorb organic matter, residual chlorine, etc. in the water and further purify the water quality. Finally, it is sent to a bag filter for filtration. The fluoride content in the water is measured to be 0.28mg / L. The water quality meets the living water standard and is discharged into the pool.

[0043] Example 2

[0044] S1, primary precipitation

[0045] S1.1 Take 40L of waste liquid containing silicon fluoride from the wastewater collection tank and put it into the regulating tank. The fluorine content in the waste liquid is measured to be 1625mg / L;

[0046] S1.2 Add calcium hydroxide (Ca(OH)2) to the waste liquid, adjust the pH to 8.2, add 1137.5g of defluorinating agent F1, and start the magnetic suspension blower for aeration for 50 minutes;

[0047] Defluorinating agent F1, by mass fraction, includes the following raw materials: 20% sodium hydroxide, 1.2% stannous chloride, 12.5% ​​polyethylene glycol, 6% ammonium sulfate, and the rest is water;

[0048] S1.3 Add 4.56g PAC and 1.15g PAM to the wastewater, and aerate it at 150r / min with a Roots blower to make the tiny particles and colloids in the wastewater condense into larger flocs, and then separate them in a sedimentation and flocculation tank. The fluorine content of the clarified wastewater after defluorination is measured to be 3.7mg / L.

[0049] The remaining steps are the same as those in Example 1: in S2, the secondary ion exchange, the fluorine content of the defluorinated exchange liquid is determined to be 0.36 mg / L, and in S3, the tertiary filtration, the fluorine content of the water is determined to be 0.22 mg / L.

[0050] Example 3

[0051] S1, primary precipitation

[0052] S1.1 Take 40L of waste liquid containing silicon fluoride from the wastewater collection tank and put it into the regulating tank. The fluorine content in the waste liquid is measured to be 1646mg / L;

[0053] S1.2 Add calcium hydroxide (Ca(OH)2) to the waste liquid, adjust the pH to 8.5, add 1152.2g of defluorinating agent F1, and start the magnetic suspension blower for aeration for 50 minutes;

[0054] Defluorinating agent F1, by mass fraction, includes the following raw materials: 25% sodium hydroxide, 0.2% stannous chloride, 15% polyethylene glycol, 7% ammonium sulfate, and the rest is water;

[0055] S1.3 Add 4.65g PAC and 1.16g PAM to the wastewater, and aerate it at 150r / min with a Roots blower to make the tiny particles and colloids in the wastewater condense into larger flocs, and then separate them in a sedimentation and flocculation tank. The fluorine content of the clarified wastewater after defluorination is measured to be 4.7mg / L.

[0056] The remaining steps are the same as those in Example 1: in S2, the secondary ion exchange, the fluorine content of the defluorinated exchange liquid is determined to be 0.46 mg / L, and in S3, the tertiary filtration, the fluorine content of the water is determined to be 0.25 mg / L.

[0057] Example 4

[0058] S1, primary precipitation

[0059] S1.1 Take 40L of waste liquid containing silicon fluoride from the wastewater collection tank and put it into the regulating tank. The fluorine content in the waste liquid is measured to be 1630mg / L;

[0060] S1.2 Add calcium hydroxide (Ca(OH)2) to the waste liquid, adjust the pH to 8.2, add 1141g of defluorinating agent F1, and start the magnetic suspension blower for aeration for 50 minutes;

[0061] Defluorinating agent F1, by mass fraction, includes the following raw materials: 20% sodium hydroxide, 0.5% stannous chloride, 10% polyethylene glycol, 4.8% ammonium sulfate, 1.2% sodium polyphosphate, and the rest is water;

[0062] S1.3 Add 4.55g PAC and 1.15g PAM to the wastewater, and aerate it at 150r / min with a Roots blower to make the tiny particles and colloids in the wastewater condense into larger flocs, and then separate them in a sedimentation and flocculation tank. The fluorine content of the clarified wastewater after defluorination is measured to be 3.5mg / L.

[0063] The remaining steps are the same as those in Example 1: in S2, the secondary ion exchange, the fluorine content of the defluorinated exchange liquid is determined to be 0.34 mg / L, and in S3, the tertiary filtration, the fluorine content of the water is determined to be 0.2 mg / L.

[0064] Example 5

[0065] S1, primary precipitation

[0066] S1.1 Take 40L of waste liquid containing silicon fluoride from the wastewater collection tank and put it into the regulating tank. The fluorine content in the waste liquid is measured to be 1630mg / L;

[0067] S1.2 Add calcium hydroxide (Ca(OH)2) to the waste liquid, adjust the pH to 8.2, add 1141g of defluorinating agent F1, and start the magnetic suspension blower for aeration for 50 minutes;

[0068] Defluorinating agent F1, by mass fraction, includes the following raw materials: 20% sodium hydroxide, 0.5% stannous chloride, 10% polyethylene glycol, 4.4% ammonium sulfate, 1.6% sodium polyphosphate, and the rest is water;

[0069] S1.3 Add 4.57g PAC and 1.15g PAM to the wastewater, and aerate it at 150r / min with a Roots blower to make the tiny particles and colloids in the sewage condense into larger flocs, and then separate them in a sedimentation and flocculation tank. The fluorine content of the clarified wastewater after defluorination is measured to be 3.4mg;

[0070] The remaining steps are the same as those in Example 1: in S2, the secondary ion exchange, the fluorine content of the defluorinated exchange liquid is determined to be 0.32 mg / L, and in S3, the tertiary filtration, the fluorine content of the water is determined to be 0.19 mg / L.

[0071] Example 6

[0072] S1, primary precipitation

[0073] S1.1 Take 40L of waste liquid containing silicon fluoride from the wastewater collection tank and put it into the regulating tank. The fluorine content in the waste liquid is measured to be 1635mg / L;

[0074] S1.2 Add calcium hydroxide (Ca(OH)2) to the waste liquid, adjust the pH to 8.2, add 1144.5g of defluorinating agent F1, and start the magnetic suspension blower for aeration for 50 minutes;

[0075] Defluorinating agent F1, by mass fraction, includes the following raw materials: 20% sodium hydroxide, 0.5% stannous chloride, 10% polyethylene glycol, 4% ammonium sulfate, 2% sodium polyphosphate, and the rest is water;

[0076] S1.3 Add 4.58g PAC and 1.15g PAM to the wastewater, and aerate it at 150r / min with a Roots blower to make the tiny particles and colloids in the sewage condense into larger flocs, and then separate them in a sedimentation and flocculation tank. The fluorine content of the clarified wastewater after defluorination is measured to be 3.5mg / L.

[0077] The remaining steps are the same as those in Example 1: in S2, the secondary ion exchange, the fluorine content of the defluorinated exchange liquid is determined to be 0.33 mg / L, and in S3, the tertiary filtration, the fluorine content of the water is determined to be 0.2 mg / L.

[0078] Example 7

[0079] S1, primary precipitation

[0080] S1.1 Take 50L of waste liquid containing silicon fluoride from the wastewater collection tank and put it into the regulating tank. The fluorine content in the waste liquid is measured to be 1765mg / L;

[0081] S1.2 Add calcium hydroxide (Ca(OH)2) to the waste liquid, adjust the pH to 8.2, add 1517.9g of defluorinating agent F1, and start the magnetic suspension blower for aeration for 40 minutes;

[0082] Defluorinating agent F1, by mass fraction, includes the following raw materials: 15% sodium hydroxide, 0.5% stannous chloride, 10% polyethylene glycol, 5% ammonium sulfate, and the rest is water;

[0083] S1.3 Add 6.38g PAC and 1.83g PAM to the wastewater, and aerate it at 200r / min through a Roots blower to make the tiny particles and colloids in the sewage condense into larger flocs, and then separate them in a sedimentation and flocculation tank. The fluorine content of the clarified wastewater after defluorination is measured to be 4.9mg / L;

[0084] S2, Secondary Ion Exchange

[0085] The clarified liquid in the first-stage defluorination process is sent to an ion exchange resin pool using a strong alkaline anion exchange resin D201 for ion exchange. The resin filling amount in the ion exchange resin pool is 30% of the treated water volume. For example, if the treated water volume is 10m / h, the resin filling amount is 3m, the flow rate is controlled to be 10m / h, and the contact time is 60min. The fluorine content of the defluorinated exchange liquid is measured to be 0.48mg / L.

[0086] In addition, the regeneration cycle is determined according to the adsorption saturation of the ion exchange resin. After the ion exchange resin is saturated with adsorption, a regeneration agent is used for regeneration. The regeneration agent is a mixed solution of sodium hydroxide and sodium chloride. The concentration of the regeneration agent is 10%, the regeneration flow rate is 2m / h, and the regeneration time is 40min.

[0087] S3, three-stage filtration

[0088] The exchange liquid removed from the secondary defluorination process is first sent to a sand filter tank with quartz sand of 0.5-1.2mm in size as filter material and a filter layer thickness of 1000mm for filtration at a flow rate of 10m / h to further remove suspended particles and residual flocs in the water and improve the water quality. It is then sent to an activated carbon filter tank with activated carbon of 2-4mm in size as filter material and a filter layer thickness of 800mm for filtration to further adsorb organic matter, residual chlorine, etc. in the water and further purify the water quality. Finally, it is sent to a bag filter for filtration. The fluoride content in the water is measured to be 0.27mg / L. The water quality meets the living water standard and is discharged into the pool.

[0089] Example 8

[0090] S1, primary precipitation

[0091] S1.1 Take 45L of waste liquid containing silicon fluoride from the wastewater collection tank and put it into the regulating tank. The fluorine content in the waste liquid is measured to be 1718mg / L;

[0092] S1.2 Add calcium hydroxide (Ca(OH)2) to the waste liquid, adjust the pH to 8.2, add 1314.27g of defluorinating agent F1, and start the magnetic suspension blower for aeration for 30 minutes;

[0093] Defluorinating agent F1, by mass fraction, includes the following raw materials: 15% sodium hydroxide, 0.5% stannous chloride, 10% polyethylene glycol, 4.8% ammonium sulfate, % sodium tripolyphosphate, and the rest is water;

[0094] S1.3 Add 5.91g PAC and 1.97g PAM to the wastewater, and aerate it at 200r / min through a Roots blower to make the tiny particles and colloids in the sewage condense into larger flocs, and then separate them in a sedimentation and flocculation tank. The fluorine content of the clarified wastewater after defluorination is measured to be 3.7mg / L;

[0095] S2, Secondary Ion Exchange

[0096] The clarified liquid in the first-stage defluorination process is sent to an ion exchange resin pool using a strong alkaline anion exchange resin D201 for ion exchange. The resin filling amount in the ion exchange resin pool is 30% of the treated water volume. For example, if the treated water volume is 10m / h, the resin filling amount is 3m, the flow rate is controlled to be 10m / h, and the contact time is 60min. The fluorine content of the defluorinated exchange liquid is measured to be 0.33mg / L.

[0097] In addition, the regeneration cycle is determined according to the adsorption saturation of the ion exchange resin. After the ion exchange resin is saturated with adsorption, a regeneration agent is used for regeneration. The regeneration agent is a mixed solution of sodium hydroxide and sodium chloride. The concentration of the regeneration agent is 5%, the regeneration flow rate is 4m / h, and the regeneration time is 60min.

[0098] S3, three-stage filtration

[0099] The exchange liquid removed from the secondary defluorination process is first sent to a sand filter tank with quartz sand of 0.5-1.2mm in size as filter material and a filter layer thickness of 700mm for filtration at a flow rate of 10m / h to further remove suspended particles and residual flocs in the water and improve the water quality. It is then sent to an activated carbon filter tank with activated carbon of 2-4mm in size as filter material and a filter layer thickness of 500mm for filtration to further adsorb organic matter, residual chlorine, etc. in the water and further purify the water quality. Finally, it is sent to a bag filter for filtration. The fluoride content in the water is measured to be 0.23mg / L. The water quality meets the living water standard and is discharged into the pool.

[0100] Comparative Example 1

[0101] S1, primary precipitation

[0102] S1.1 Take 40L of waste liquid containing silicon fluoride from the wastewater collection tank and put it into the regulating tank. The fluorine content in the waste liquid is measured to be 1630mg / L;

[0103] S1.2 Add calcium hydroxide (Ca(OH)2) to the waste liquid, adjust the pH to 8, add 762g of calcium chloride, turn on the magnetic suspension blower for aeration for 50 minutes, and settle for 3 hours.

[0104] S1.3 Add 3.25g PAC and 0.78g PAM to the wastewater, and aerate it at 150r / min with a Roots blower to make the tiny particles and colloids in the sewage condense into larger flocs, and then separate them in a sedimentation and flocculation tank. The fluorine content of the clarified wastewater after defluorination is measured to be 305mg / L.

[0105] The remaining steps are the same as those in Example 1: in S2, the secondary ion exchange, the fluorine content of the defluorinated exchange liquid is determined to be 46.1 mg / L, and in S3, the tertiary filtration, the fluorine content of the water quality is determined to be 44.6 mg / L.

[0106] Comparative Example 2

[0107] S1. The primary precipitation process is the same as in Example 1. The fluorine content in 40L of waste liquid is determined to be 1634mg / L. The pH is adjusted to 8, and the defluorinating agent F1 is added to 1143.8. After precipitation treatment, the fluorine content of the defluorinated clarified waste liquid is determined to be 4.8mg / L.

[0108] S2, secondary adsorption

[0109] The clarified liquid in the first-stage defluorination was sent to an adsorption tank containing activated alumina. The amount of activated alumina adsorbent added was 800 g, the stirring time was 120 min, the empty bed residence time was 20 min, and the fluorine content of the defluorinated exchange liquid was measured to be 2.1 mg / L.

[0110] In addition, the regeneration cycle is determined according to the adsorption saturation of the ion exchange resin. After the ion exchange resin is saturated with adsorption, a regeneration agent is used for regeneration. The regeneration agent is a sodium hydroxide solution with a regeneration agent concentration of 3%, a regeneration flow rate of 3 m / h, and a regeneration time of 90 min.

[0111] S3. The three-stage filtration is the same as in Example 1, and the fluoride content of the water is measured to be 1.6 mg / L.

[0112] Comparative Example 3

[0113] S1. The primary precipitation process is partially the same as that of Example 1, except that: the defluorinating agent F1, by mass fraction, includes the following raw materials: 15% sodium hydroxide, 0.5% stannous chloride, 10% polyethylene glycol, 2% ammonium sulfate, and the rest is water; the fluorine content in 40L of waste liquid is measured to be 1633mg / L; the pH is adjusted to 8, and the defluorinating agent F1 is added to 1143.1, and after precipitation treatment; the fluorine content of the clarified waste liquid after defluorination is measured to be 38.6mg / L;

[0114] The remaining steps are the same as those in Example 1: in S2, the secondary ion exchange, the fluorine content of the defluorinated exchange liquid is determined to be 4.9 mg / L, and in S3, the tertiary filtration, the fluorine content of the water quality is determined to be 4.1 mg / L.

[0115] Comparative Example 4

[0116] S1. The primary precipitation process is partially the same as that of Example 1, except that: the defluorinating agent F1, by mass fraction, includes the following raw materials: 15% sodium hydroxide, 0.5% stannous chloride, 10% polyethylene glycol, 6% sodium polyphosphate, and the rest is water; the fluorine content in 40L of waste liquid is measured to be 1630mg / L; the pH is adjusted to 8, 1141 of defluorinating agent F1 is added, and after precipitation treatment; the fluorine content of the clarified waste liquid after defluorination is measured to be 105.3mg / L;

[0117] The remaining steps are the same as those in Example 1: in S2, the secondary ion exchange, the fluorine content of the defluorinated exchange liquid is determined to be 13.3 mg / L, and in S3, the tertiary filtration, the fluorine content of the water quality is determined to be 12.5 mg / L.

[0118] Comparative Example 5

[0119] S1, the primary precipitation process is the same as that of Example 1, except that: the amount of defluorinating agent F1 added; the fluorine content in 40L of waste liquid was measured to be 1634mg / L; the pH was adjusted to 8, the defluorinating agent F1 was added to 1078.45, and after precipitation treatment; the fluorine content of the clarified waste liquid after defluorination was measured to be 11.8mg / L;

[0120] The remaining steps are the same as those in Example 1: in S2, the secondary ion exchange, the fluorine content of the defluorinated exchange liquid is determined to be 1.3 mg / L, and in S3, the tertiary filtration, the fluorine content of the water is determined to be 0.9 mg / L.

[0121] Comparative Example 6

[0122] S1, the primary precipitation process is the same as that of Example 1, except that: the amount of defluorinating agent F1 added; the fluorine content in 40L of waste liquid was measured to be 1634mg / L; the pH was adjusted to 8, the defluorinating agent F1 was added to 1163.4, and after precipitation treatment; the fluorine content of the clarified waste liquid after defluorination was measured to be 4.4mg / L;

[0123] The remaining steps are the same as those in Example 1: in S2, the secondary ion exchange, the fluorine content of the defluorinated exchange liquid is determined to be 0.43 mg / L, and in S3, the tertiary filtration, the fluorine content of the water is determined to be 0.29 mg / L.

[0124] The waste liquids obtained by treatment in Examples 1 to 8 and Comparative Examples 1 to 6 were tested for fluoride ion content. The test results are shown in Table 1.

[0125] Table 1

[0126]

[0127] As can be seen from Table 1, in the primary precipitation treatment of Comparative Example 1, calcium chloride is used instead of defluoridation agent F1, and the efficiency of fluorine removal is low, and it is difficult to meet the standard for wastewater discharge; the secondary adsorption of Comparative Example 2 replaces the secondary ion exchange, and the efficiency of fluorine removal is low, and the fluorine content standard for domestic water cannot be met; the content of ammonium sulfate in the defluoridation agent F1 in Comparative Example 3 is too low, and the defluoridation agent F1 in Comparative Example 4 contains only sodium polyphosphate, and the efficiency of fluorine removal is low. After the primary precipitation, the standard for wastewater discharge cannot be met, which affects the secondary ion exchange and the tertiary filtration, resulting in the failure to meet the fluorine content standard for domestic water. In addition, the content of ammonium sulfate in the defluoridation agent F1 is too high, which will affect the water quality content, and it is necessary to increase the treatment process and increase the workload; the input amount of defluoridation agent F1 in Comparative Example 5 is too low, and after the primary precipitation, the fluorine content is slightly higher than the standard for wastewater discharge, resulting in a shortened regeneration cycle of the ion exchange resin, and the input amount of defluoridation agent F1 in Comparative Example 6 is too high. Although the removal rate of fluoride ions is high, it will affect the water quality content, increase the treatment process, and increase the workload.

[0128] The present invention adopts three-stage defluorination: primary precipitation-secondary ion exchange-third-stage filtration, and adopts a defluorination agent F1 composed of appropriate amounts of sodium hydroxide, stannous chloride, polyethylene glycol, ammonium sulfate and / or phosphate additives and water, and adds an appropriate amount of the defluorination agent F1 according to the fluorine content in the waste liquid. The defluorinated clarified liquid after the primary precipitation reaches the standard of waste water discharge and is less than 5 mg / L, and the defluorinated exchange liquid after the subsequent secondary ion exchange reaches the fluorine content standard of domestic water and is less than 0.5 mg / L. After the third-stage filtration, the water quality is further improved, and other requirements meet the standard of domestic water, and the fluorine content is further reduced to less than 0.3 mg / L, and the removal rate of fluorine ions is significantly improved to more than 99.9%. The process is simple and the effect is good.

[0129] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit and essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0130] 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 removing fluorine from high-purity quartz sand pickling wastewater, characterized in that: The following steps are involved: S1, primary precipitation S1.1 Take the waste liquid containing silicon fluoride from the wastewater collection tank and place it in the regulating tank to determine the fluorine content in the waste liquid; S1.2 adding calcium hydroxide to the waste liquid, adjusting the pH to 8-8.5, and then adding a defluorinating agent F1, the amount of which is calculated based on the weight of fluoride ions in the waste liquid, and turning on a magnetic suspension blower for aeration for 30-50 minutes; the defluorinating agent F1 includes sodium hydroxide, stannous chloride, polyethylene glycol, auxiliary additives and water; S1.3 Add polyaluminium chloride and polyacrylamide to the wastewater, and aerate it with a Roots blower to make the tiny particles and colloids in the wastewater condense into larger flocs, and then separate them in a sedimentation and flocculation tank to produce a clear liquid with defluorination; S2, Secondary Ion Exchange The clarified liquid from the first-stage defluorination is sent to an ion exchange resin pool for ion exchange, with the flow rate controlled at 5 to 20 m / h and the contact time at 20 to 60 min to produce a defluorinated exchange liquid; S3, three-stage filtration The exchange liquid removed from the secondary defluorination process is first sent to a sand filter tank for filtration at a flow rate of 5 to 10 m / h, then sent to an activated carbon filter tank for filtration, and finally sent to a bag filter for filtration. The water quality reaches the living water standard and is discharged into the pool.

2. The method for defluoridating high-purity quartz sand pickling wastewater according to claim 1, characterized in that: The calculation method based on the fluorine content in the waste liquid is: the input amount of defluorination agent F = correlation coefficient × the weight of fluoride ions in the waste liquid; the correlation coefficient is 17.0~17.

5.

3. The method for defluoridating high-purity quartz sand pickling wastewater according to claim 1, characterized in that: The defluorinating agent F1 comprises the following raw materials, calculated by mass fraction: 15-25% sodium hydroxide, 0.5-2% stannous chloride, 10-15% polyethylene glycol, 5-7% auxiliary additives and the rest water.

4. A method for defluoridating high-purity quartz sand pickling wastewater according to claim 1 or 3, characterized in that: The auxiliary additive is ammonium sulfate, or ammonium sulfate and phosphate additives.

5. A method for defluoridating high-purity quartz sand pickling wastewater according to claim 1 or 3, characterized in that: The auxiliary additives are ammonium sulfate and phosphate additives, and the mass ratio of the ammonium sulfate to the phosphate additives is 4:(1-2).

6. The method for defluoridating high-purity quartz sand pickling wastewater according to claim 1, characterized in that: The amount of PAC added is 0.4-0.45% of the amount of defluorination agent F1 added.

7. The method for defluoridating high-purity quartz sand pickling wastewater according to claim 1, characterized in that: The amount of PAM added is 0.1-0.15% of the amount of defluorination agent F1 added.

8. The method for defluoridating high-purity quartz sand pickling wastewater according to claim 1, characterized in that: The ion exchange resins in the ion exchange resin pool are strongly basic anion exchange resin IRA900 and strongly basic anion exchange resin D201.

9. A method for defluoridating high-purity quartz sand pickling wastewater according to claim 1 or 8, characterized in that: The resin filling amount in the ion exchange resin pool is 10-30% of the treated water amount.

10. The method for defluoridating high-purity quartz sand pickling wastewater according to claim 1, characterized in that: The sand filter tank uses quartz sand as the filter material, with a particle size of 0.5 to 1.2 mm and a filter layer thickness of 700 to 1000 mm; the activated carbon filter tank uses activated carbon as the filter material, with a particle size of 2 to 4 mm and a filter layer thickness of 500 to 800 mm.

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