Semiconductor fluorine-containing and phosphorus-containing waste liquid grading reaction crystallization recovery process and system

Abstract

The invention discloses a grading reaction crystallization recovery process and system for semiconductor fluorine-containing and phosphorus-containing waste liquid, the fluorine-containing and phosphorus-containing waste liquid and a lime solution react in a fluorine recovery crystallization reactor under the condition that the pH is 3-4 to form calcium fluoride crystals, and the calcium fluoride crystals are dehydrated to obtain calcium fluoride particle crystal products; the effluent of the fluorine recovery crystallization reactor, the calcium fluoride crystal dehydration filtrate, the lime solution and the calcium chloride solution react in a secondary reaction tank under the condition that the pH is 5-6, and calcium fluoride, fluorapatite, silicon dioxide and silicon-aluminum precipitates are removed through coagulation, flocculation and precipitation; effluent of the second-stage reaction tank, the lime solution and the calcium chloride solution react in the phosphorus recovery crystallization reactor under the condition that the pH is 7-8 to generate hydroxyapatite crystals, and the hydroxyapatite crystals are dehydrated to obtain hydroxyl calcium phosphate particle crystal products. Meanwhile, a high-purity calcium fluoride crystal product and a hydroxyl calcium phosphate crystal product are produced, and fluorine and phosphorus are recycled.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of wastewater treatment, in particular to a semiconductor fluorine-containing and phosphorus-containing waste liquid grading reaction crystallization recovery process and system. BACKGROUND

[0002] Driven by the massive growth of global information industry and the development of AI chips, the global semiconductor industry is developing rapidly, and the semiconductor industry has gradually surpassed the traditional steel and automobile industries and become a high-value-added and high-tech industry. In the semiconductor production process, various inorganic acids are used, among which hydrofluoric acid is mainly used for wafer etching or cleaning, and phosphoric acid is mainly used for photoresist removal or aluminum pad etching. Such mixed acid wastewater contains high concentrations of fluorine and phosphorus pollutants, as well as impurities such as silicon.

[0003] For such fluorine-containing and phosphorus-containing waste acid solution, the fluorine concentration is as high as several hundred to several thousand mg / L, and the phosphorus concentration can also be as high as several hundred mg / L. The traditional method is to directly add alkaline reagents such as lime or liquid alkali and calcium chloride to the wastewater for neutralization, precipitation and other reactions to remove fluorine, phosphorus and other pollutants in the water through the principle of chemical precipitation. In this process, a large amount of low-purity chemical sludge is generated due to the competition between phosphorus and fluorine, and the main components are calcium fluoride, calcium fluorophosphate and silicon dioxide. Such sludge cannot effectively separate the fluorine-containing and phosphorus-containing sludge, and it is difficult to purify, resulting in low purity of calcium fluoride sludge, which is difficult to produce recycling value, and high water content, which can only be disposed of as solid waste. On the one hand, it produces high treatment cost, and on the other hand, it causes serious waste of fluorine and phosphorus resources. SUMMARY

[0004] In order to overcome the above defects, the application provides a semiconductor fluorine-containing and phosphorus-containing waste liquid grading reaction crystallization recovery process and system, which can recover fluorine and phosphorus in the form of high-purity crystallization respectively and realize resource utilization.

[0005] The technical scheme adopted by the application to solve the technical problem is: a semiconductor fluorine-containing and phosphorus-containing waste liquid grading reaction crystallization recovery process, comprising the following steps:

[0006] Step one: send the fluorine-containing and phosphorus-containing waste liquid into a fluorine recovery crystallization reactor, and send lime solution into the fluorine recovery crystallization reactor, control the pH of the mixed solution in the reactor to be 3-4, and the fluorine ion reacts with the calcium ion to form calcium fluoride crystals;

[0007] Step two: the fluorine recovery crystallization reactor periodically and quantitatively discharges calcium fluoride crystals, and the discharged calcium fluoride crystals are dehydrated to obtain high-quality calcium fluoride particle crystal products with a purity of not less than 85% and a water content of less than 30%;

[0008] Step three: the filtrate produced when the fluorine recovery crystallization reactor in step one and the calcium fluoride crystals in step two are dehydrated is mixed and sent into the reaction zone of the secondary reaction tank, while lime solution and calcium chloride solution are added to the reaction zone of the secondary reaction tank, the pH of the reaction zone of the secondary reaction tank is controlled between 5-6, and the molar ratio of total calcium to fluorine is controlled between 0.5-0.6, the residual fluorine ions in the wastewater react with phosphate ions and calcium ions to generate calcium fluoride and fluorapatite, achieving the removal of residual fluorine ions, after more than 95% of the fluorine ions in the fluorine-containing and phosphorus-containing waste liquid are removed in the form of calcium fluoride crystals by the fluorine recovery crystallization reactor, a large amount of phosphate ions, a small amount of fluorine ions, soluble silicon and aluminum ions remain in the wastewater, in the secondary reaction tank, by adding lime solution and calcium chloride solution, the pH of the wastewater is adjusted to 5-6, the residual fluorine ions react with calcium ions to generate calcium fluoride, while the residual fluorine ions, calcium ions and a small amount of phosphate ions combine to generate fluorapatite, a small amount of soluble silicon, aluminum ions and calcium ions in the wastewater generate silicon-aluminum precipitate (calcium aluminum silicate);

[0009] Step four: the effluent from the reaction zone of the secondary reaction tank enters the coagulation and sedimentation zone of the secondary reaction tank, and PAC and PAM are added to the coagulation and sedimentation zone of the secondary reaction tank for coagulation, flocculation and sedimentation treatment to remove calcium fluoride, fluorapatite, silicon dioxide and silicon-aluminum precipitate in the wastewater, after coagulation and flocculation by adding PAC and PAM, the calcium fluoride, fluorapatite, silicon dioxide and silicon-aluminum in the wastewater form lump-shaped precipitate, which finally forms chemical sludge in the sedimentation tank;

[0010] Step five: the effluent from the coagulation and sedimentation zone of the secondary reaction tank enters the phosphorus recovery crystallization reactor, and lime solution and calcium chloride solution are added to the phosphorus recovery crystallization reactor, the pH of the mixed liquor in the phosphorus recovery crystallization reactor is controlled between 7-8, and the molar ratio of total calcium to phosphorus is controlled between 1.67-1.85, calcium ions combine with phosphorus and hydroxyl ions in the wastewater to generate hydroxyapatite crystals, the fluorine and phosphorus contents in the effluent from the phosphorus recovery crystallization reactor meet the discharge requirements, wherein the pH of the reaction tank is controlled by adding lime solution, and the molar ratio of total calcium to phosphorus is controlled by controlling the flow rates of the calcium chloride solution and the lime solution;

[0011] Step six: the phosphorus recovery crystallization reactor periodically and quantitatively discharges hydroxyapatite crystals, and the hydroxyapatite crystals are dehydrated to obtain calcium hydroxyphosphate granular crystal product.

[0012] By adjusting the pH of the wastewater in stages, the pH of the wastewater is controlled in a gradient, thereby achieving the stepwise removal of specific pollutants: the fluorine-containing and phosphorus-containing waste liquid is strongly acidic, lime solution is added in the acidic region to preferentially remove fluorine and block the reaction of phosphate and calcium ions, thereby obtaining high-purity calcium fluoride; the weakly acidic and neutral region removes the remaining fluorine and impurities such as silicon and aluminum ions, purifying the reaction environment for phosphorus crystallization; finally, phosphorus is directionally recovered in a neutral and alkaline environment.

[0013] Both lime and calcium chloride are common calcium salts, which are often used for the removal of fluorine and phosphorus. In the actual process, lime has the functions of synchronous pH adjustment and calcium source provision; calcium chloride is easy to dissolve in water and is often used to provide calcium source. The use of lime alone is prone to the problem of mismatch between reaction pH and calcium source amount, and the use of lime and calcium chloride as double calcium sources in the present application can meet the requirements of both staged pH adjustment and sufficient calcium ions for reducing fluorine and phosphorus to a low level.

[0014] The present application can obtain high-purity calcium fluoride crystals by controlling the pH of wastewater to limit the reaction of phosphorus and calcium under acidic conditions; other impurities in the water can be removed under neutral to weakly acidic conditions by adjusting the pH, and high-purity calcium hydroxyphosphate crystals can be obtained in the neutral to alkaline region by further adjusting the pH. The present process can simultaneously produce calcium fluoride and calcium hydroxyphosphate crystals, realizing the resource utilization of fluorine and phosphorus.

[0015] As a further improvement of the present application, the fluorine- and phosphorus-containing waste liquid is first subjected to homogenization treatment in a fluorine-containing wastewater conditioning tank before entering the fluorine recovery crystallization reactor, lime solids are stirred and configured in the lime tank at a concentration of 2%-5%, and calcium chloride solution is configured in the calcium chloride tank at a concentration of 5%-10%. The advance homogenization treatment of the fluorine- and phosphorus-containing waste liquid can ensure the stability of reagent addition and resource production during the treatment process.

[0016] As a further improvement of the present application, the coagulation and sedimentation zone of the secondary reaction tank periodically discharges chemical sludge containing calcium fluoride, a small amount of fluorapatite, silicon dioxide and silicon-aluminum sediment, and the chemical sludge is subjected to pressure filtration treatment to form waste solid.

[0017] As a further improvement of the present application, the filtrate produced during the dewatering treatment of calcium fluoride crystals from the effluent of the fluorine recovery crystallization reactor and the pressure filtration liquid produced by pressure filtration treatment of the chemical sludge discharged from the coagulation and sedimentation zone of the secondary reaction tank are respectively sent to the primary effluent conditioning tank for homogenization treatment, and the effluent of the primary effluent conditioning tank is sent to the secondary reaction tank.

[0018] As a further improvement of the present application, the effluent of the coagulation and sedimentation zone of the secondary reaction tank and the filtrate produced during the dewatering treatment of hydroxyapatite crystals in step six are sent to the secondary effluent conditioning tank for homogenization treatment, and the effluent of the secondary effluent conditioning tank is sent to the phosphorus recovery crystallization reactor.

[0019] As a further improvement of the present application, in the step one, the residence time of the fluorine-containing phosphorus-containing waste liquid and the lime solution in the fluorine recovery crystallization reactor is controlled to be 30-60 minutes; the total hydraulic residence time of the secondary reaction tank is 1-3 hours, the fluoride ion concentration of the effluent of the coagulation sedimentation zone of the secondary reaction tank is lower than 8 mg / L; the reaction time of the mixed solution of the waste water, the lime solution and the calcium chloride solution in the phosphorus recovery crystallization reactor is 1-2 hours, and the phosphorus concentration in the effluent of the phosphorus recovery crystallization reactor is lower than 1 mg / L.

[0020] As a further improvement of the present application, the effluent of the phosphorus recovery crystallization reactor enters the subsequent treatment process of the plant area, is treated to reach the standard, and is discharged. The subsequent treatment process is mainly used for removing other harmful substances and organic matters in the water, so that the water can reach the discharge standard or be reused by the plant.

[0021] The application discloses a semiconductor fluorine-containing phosphorus-containing waste liquid grading reaction crystallization recovery system which comprises a fluorine-containing waste water adjusting pool, a lime pool, a calcium chloride pool, a fluorine recovery crystallization reactor, a first dewatering device, a secondary reaction pool, a filter press, a phosphorus recovery crystallization reactor, a second dewatering device, a first pH meter, a second pH meter, a third pH meter, a first waste water lifting pump, a second waste water lifting pump, a first dosing pump, a second dosing pump, a third dosing pump, a fourth dosing pump, a fifth dosing pump and a control system, the first waste water lifting pump can pump the fluorine-containing phosphorus-containing waste liquid in the fluorine-containing waste water adjusting pool into the fluorine recovery crystallization reactor, the first dosing pump, the second dosing pump and the third dosing pump can pump the lime solution in the lime pool into the fluorine recovery crystallization reactor, the reaction area of the secondary reaction pool and the phosphorus recovery crystallization reactor respectively, the fourth dosing pump and the fifth dosing pump can pump the calcium chloride solution in the calcium chloride pool into the reaction area of the secondary reaction pool and the phosphorus recovery crystallization reactor respectively, the first pH meter, the second pH meter and the third pH meter can detect the pH values of the mixed liquid in the fluorine recovery crystallization reactor, the reaction area of the secondary reaction pool and the phosphorus recovery crystallization reactor respectively in real time, and the first pH meter, the second pH meter and the third pH meter can transmit the detection data to the control system, the water outlet of the fluorine recovery crystallization reactor can enter the reaction area of the secondary reaction pool through a pipeline, the crystal discharge port of the fluorine recovery crystallization reactor is connected with the first dewatering device through a pipeline, the secondary reaction pool further comprises a coagulation area, a flocculation area and a sedimentation area, the reaction area, the coagulation area, the flocculation area and the sedimentation area of the secondary reaction pool are sequentially connected, the waste water which has been sufficiently reacted in the reaction area sequentially enters the coagulation area, the flocculation area and the sedimentation area to carry out coagulation reaction, flocculation reaction and sedimentation sludge-water separation, the water outlet of the sedimentation area of the secondary reaction pool can be sent into the phosphorus recovery crystallization reactor by the second waste water lifting pump through a pipeline, the crystal discharge port of the phosphorus recovery crystallization reactor is connected with the second dewatering device through a pipeline, the sludge discharge port of the sedimentation area of the secondary reaction pool is connected with the filter press through a pipeline, the first dewatering device and the second dewatering device can respectively dewater calcium fluoride crystals and hydroxyapatite crystals, the filter press can filter the chemical sludge discharged from the sedimentation area of the secondary reaction pool to form waste solid, and the control system controls the operation of the first dewatering device, the filter press, the filter press, the first waste water lifting pump, the second waste water lifting pump, the first dosing pump, the second dosing pump, the third dosing pump, the fourth dosing pump and the fifth dosing pump. The control system can control the flow of each dosing pump through the flow of the first and second waste water lifting pumps and the real-time detection data of each pH meter, realize intelligent control of the reaction, and ensure sufficient resource treatment of fluorine and phosphorus.

[0022] As a further improvement of the present application, a first effluent regulating tank, a second effluent regulating tank, a first filtrate conveying pump, a second filtrate conveying pump and a third filtrate conveying pump are also provided, the effluent outlet of the fluorine recovery crystallization reactor is communicated with the water inlet of the first effluent regulating tank through a pipeline, the effluent of the fluorine recovery crystallization reactor flows into the first effluent regulating tank, the filtrate tank of the first dewatering device and the filter press is also communicated with the water inlet of the first effluent regulating tank through a pipeline, the first filtrate conveying pump and the second filtrate conveying pump can respectively pump the filtrate in the filtrate tank of the first dewatering device and the filter press into the first effluent regulating tank, the effluent outlet of the first effluent regulating tank is communicated with the reaction zone of the secondary reaction tank through a pipeline, the effluent outlet of the sedimentation zone of the secondary reaction tank is communicated with the water inlet of the second effluent regulating tank through a pipeline, the effluent of the sedimentation zone of the secondary reaction tank flows into the second effluent regulating tank, the filtrate tank of the second dewatering device is communicated with the water inlet of the second effluent regulating tank through a pipeline, the third filtrate conveying pump can pump the filtrate in the filtrate tank of the second dewatering device into the second effluent regulating tank, the effluent outlet of the second effluent regulating tank is communicated with the water inlet of the phosphorus recovery crystallization reactor through a pipeline, a stirrer is arranged in each of the first effluent regulating tank, the second effluent regulating tank and the fluorine-containing wastewater regulating tank, and the stirrer can stir and homogenize the liquid in the first effluent regulating tank, the second effluent regulating tank and the fluorine-containing wastewater regulating tank.

[0023] As a further improvement of the present application, a medicament stirrer is arranged in each of the lime tank and the calcium chloride tank, the medicament stirrer can respectively stir the lime solution in the lime tank and the calcium chloride solution in the calcium chloride tank, a coagulant dosing device and a flocculant dosing device are also provided, the control system can control the coagulant dosing device and the flocculant dosing device to quantitatively add coagulant and flocculant to the coagulation zone and the flocculation zone of the secondary reaction tank, and a control valve is arranged at each of the crystal discharge outlet of the fluorine recovery crystallization reactor, the sludge discharge outlet of the sedimentation zone of the secondary reaction tank and the crystal discharge outlet of the phosphorus recovery crystallization reactor, and the control system controls each valve to realize periodic and quantitative crystal and sludge discharge.

[0024] The beneficial effects of the present application are: the present application realizes pH gradient control of fluorine-containing and phosphorus-containing waste liquid by adding lime solution and calcium chloride solution in stages, and then realizes the removal of specific pollutants in stages: the original fluorine-containing and phosphorus-containing waste liquid is strongly acidic, the lime solution is added in the acidic region to remove fluorine preferentially and block the reaction of phosphate and calcium ions, so that high-purity calcium fluoride is obtained, the reagent dosage is reduced, and the reagent cost is reduced; the weak acid near neutral region removes the remaining fluorine and impurities such as silicon and aluminum ions, and purifies the reaction environment for phosphorus crystallization; phosphorus is recovered in a neutral alkaline environment; the present application uses lime solution and calcium chloride solution as double calcium sources for collaborative addition, the lime solution is used to control the reaction pH, and the calcium fluoride ratio is supplemented by the calcium chloride solution, which can meet the needs of staged pH adjustment and ensure that sufficient calcium ions reduce fluorine and phosphorus to a dischargeable level, the reaction of phosphorus and calcium under acidic conditions is limited by controlling the pH, and high-purity calcium fluoride crystals can be obtained; other impurities in the water quality are removed after the pH is increased, and high-purity calcium hydroxyl phosphate crystals can be obtained in a neutral alkaline region, the present application can simultaneously produce high-purity (purity above 85%) calcium fluoride crystal products and calcium hydroxyl phosphate crystal products, realize fluorine and phosphorus resources, and the fluorine ion recovery rate is above 90%, only a small amount of fluorine ions and other impurities are left to form sludge in the secondary reaction tank, and the amount of sludge is greatly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The system principle diagram of the present application is shown in the figure;

[0026] Figure 2 The secondary reaction tank principle diagram of the present application is shown in the figure;

[0027] Figure 3 The system principle diagram of the comparative example is shown in the figure. DETAILED DESCRIPTION

[0028] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in a clear and complete manner in combination with the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. Therefore, the detailed description of the embodiments of the present application provided below is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0029] Embodiment: The fluorine-containing and phosphorus-containing waste liquid generated by a certain semiconductor manufacturing plant has the following indexes as shown in the table:

[0030] Indicator pH Fluoride mg / L Orthophosphorus mg / L Silicon mg / L Detection value <1.2 2754 697 387

[0031] Comparative Example:

[0032] The original treatment method uses lime method to simultaneously remove fluorine and phosphorus, and the treatment process is as follows:

[0033] The raw water and the lime solution enter the reaction tank at the same time, and the reaction is controlled at a certain pH value (pH 8-9). The effluent successively enters the coagulation tank, flocculation tank and sedimentation tank to further reduce the content of fluorine, silicon and the like in the water, and to separate the sludge and water, and the chemical sludge produced is dewatered in a sludge dewatering device, and the mixed sludge cake obtained is outsourced for treatment. The effluent fluorine can be reduced to below 10 mg / L, and the phosphorus can be reduced to 5.5 mg / L. The sludge production per ton of water in the system is 21.3 kg.

[0034] The specific steps of the semiconductor fluorine-containing and phosphorus-containing waste liquid fractional reaction crystallization recovery process of the present application are as follows:

[0035] (1). The wastewater is collected in a fluorine-containing wastewater conditioning tank for homogenization, the lime solid is stirred and configured in a lime tank at a concentration of 2%-5%, and the calcium chloride solution in the calcium chloride tank has a concentration of 5%-10%;

[0036] (2). The lime solution in the lime tank and the wastewater in the fluorine-containing wastewater conditioning tank are fed into a fluorine recovery crystallization reactor according to a certain proportion, the pH in the reactor is controlled at 3.5-3.8, the residence time of the reactor is controlled at 30-45 minutes, and the fluorine removal rate of the effluent from the fluorine recovery crystallization reactor reaches 95%;

[0037] (3). The calcium fluoride crystals discharged from the fluorine recovery crystallization reactor are dewatered by a first dewatering device to obtain high-quality calcium fluoride crystal products with a purity of more than 85%, and the absolute dry yield of calcium fluoride per ton of water is 7.8 kg;

[0038] (4). The effluent from the fluorine recovery crystallization reactor and the filtrate produced by the first dewatering device are mixed and homogenized in a first effluent conditioning tank, the effluent from the first effluent conditioning tank, the calcium chloride solution and the lime solution are fed into a second reaction tank, the pH in the second reaction tank is controlled at 5.2-5.5, PAC and PAM are used for coagulation and sedimentation, the effluent from the sedimentation zone of the second reaction tank is clear, the sludge from the sedimentation zone of the second reaction tank is dewatered by a filter press and then is outsourced for waste solid treatment, and the sludge production per ton of water in the second reaction tank is 6 kg;

[0039] (5). The effluent from the second reaction tank and the filter press filtrate are homogenized in a second effluent conditioning tank, at this time the fluorine ion in the water is below 8 mg / L, the silicon concentration is reduced to below 20 mg / L, and the orthophosphorus concentration is reduced to about 200 mg / L;

[0040] (6). The secondary effluent in the adjusting tank, the lime solution in the lime tank and the calcium chloride solution in the calcium chloride tank are added into the phosphorus recovery crystallization reactor according to the calcium-phosphorus molar ratio of 1.74, the lime solution is added for pH adjustment according to the pH of the mixed solution through the self-control linkage program of the control system, so that the reaction pH is between 7.1 and 7.5, after the reaction, the orthophosphorus concentration of the effluent of the phosphorus recovery crystallization reactor is reduced to below 1 mg / L, the calcium hydroxyl phosphate crystals in the phosphorus recovery crystallization reactor are periodically and quantitatively discharged, the calcium hydroxyl phosphate crystals enter the second dewatering device, the calcium hydroxyl phosphate product is obtained, the purity is greater than 95%, and 1.5 kg of absolutely dry calcium hydroxyl phosphate crystals is generated per ton of water.m 3

[0041] The two kinds of implementation modes and effect comparison are shown in the following table:

[0042]

[0043]

[0044] From the two kinds of implementation modes, no matter from the dosing amount, sludge yield, and resource effect, the present application has obvious advantages.

[0045] The semiconductor fluorine-containing phosphorus-containing waste liquid fractional reaction crystallization recovery system used in the semiconductor fluorine-containing phosphorus-containing waste liquid fractional reaction crystallization recovery process comprises a fluorine-containing waste water adjusting pool, a lime pool, a calcium chloride pool, a fluorine recovery crystallization reactor, a first dewatering device, a secondary reaction pool, a filter press, a phosphorus recovery crystallization reactor, a second dewatering device, a first pH meter, a second pH meter, a third pH meter, a first waste water lifting pump, a second waste water lifting pump, a first dosing pump, a second dosing pump, a third dosing pump, a fourth dosing pump, a fifth dosing pump, a first effluent adjusting pool, a secondary effluent adjusting pool, a first filtrate conveying pump, a second filtrate conveying pump, a third filtrate conveying pump and a control system, the first waste water lifting pump can pump the fluorine-containing phosphorus-containing waste liquid in the fluorine-containing waste water adjusting pool into the fluorine recovery crystallization reactor, the first dosing pump, the second dosing pump and the third dosing pump can pump the lime solution in the lime pool into the fluorine recovery crystallization reactor, the reaction zone of the secondary reaction pool and the phosphorus recovery crystallization reactor respectively, the fourth dosing pump and the fifth dosing pump can pump the calcium chloride solution in the calcium chloride pool into the reaction zone of the secondary reaction pool and the phosphorus recovery crystallization reactor respectively, the first pH meter, the second pH meter and the third pH meter can detect the pH value of the mixed liquid in the fluorine recovery crystallization reactor, the reaction zone of the secondary reaction pool and the phosphorus recovery crystallization reactor respectively in real time, and the first pH meter, the second pH meter and the third pH meter can transmit the detection data to the control system, the effluent outlet of the fluorine recovery crystallization reactor is communicated with the water inlet of the first effluent adjusting pool through a pipeline, the effluent of the fluorine recovery crystallization reactor flows into the first effluent adjusting pool, the effluent outlet of the first effluent adjusting pool is communicated with the reaction zone of the secondary reaction pool through a pipeline, the crystal discharge port of the fluorine recovery crystallization reactor is connected with the first dewatering device through a pipeline, the secondary reaction pool further comprises a coagulation zone, a flocculation zone and a sedimentation zone, the reaction zone, the coagulation zone, the flocculation zone and the sedimentation zone of the secondary reaction pool are sequentially communicated, the waste water reacted sufficiently in the reaction zone sequentially enters the coagulation zone, the flocculation zone and the sedimentation zone to carry out coagulation reaction, flocculation reaction and sedimentation sludge-water separation, the sedimentation zone of the secondary reaction pool is communicated with the water inlet of the secondary effluent adjusting pool through a pipeline, the effluent of the sedimentation zone of the secondary reaction pool flows into the secondary effluent adjusting pool, the effluent outlet of the secondary effluent adjusting pool is communicated with the water inlet of the phosphorus recovery crystallization reactor through a pipeline, the effluent of the secondary effluent adjusting pool can be pumped into the phosphorus recovery crystallization reactor by the second waste water lifting pump through a pipeline, the crystal discharge port of the phosphorus recovery crystallization reactor is connected with the second dewatering device through a pipeline, the sludge discharge port of the sedimentation zone of the secondary reaction pool is connected with the filter press through a pipeline, the first dewatering device and the second dewatering device can carry out dewatering on calcium fluoride crystals and hydroxyapatite crystals respectively, the filter press can carry out pressure filtration on the chemical sludge discharged from the sedimentation zone of the secondary reaction pool to form waste solid, the filtrate pools of the first dewatering device and the filter press are also communicated with the water inlet of the first effluent adjusting pool through a pipeline, the first filtrate conveying pump and the second filtrate conveying pump can pump the filtrate in the filtrate pools of the first dewatering device and the filter press into the first effluent adjusting pool respectively.The filtrate pool of the second dewatering device is communicated with the water inlet of the secondary effluent adjusting pool through a pipeline, and the third filtrate conveying pump can pour the filtrate in the filtrate pool of the second dewatering device into the secondary effluent adjusting pool, a stirring machine is arranged in each of the primary effluent adjusting pool, the secondary effluent adjusting pool and the fluorine-containing wastewater adjusting pool, the stirring machine can stir and homogenize the liquid in the primary effluent adjusting pool, the secondary effluent adjusting pool and the fluorine-containing wastewater adjusting pool, a medicament stirring machine is arranged in each of the lime pool and the calcium chloride pool, the medicament stirring machine can stir the lime solution in the lime pool and the calcium chloride solution in the calcium chloride pool respectively, a coagulant dosing device and a flocculant dosing device are further arranged, the control system can control the coagulant dosing device and the flocculant dosing device to quantitatively add coagulant and flocculant to the coagulation zone and the flocculation zone of the secondary reaction pool, control valves are arranged at the crystal discharge port of the fluorine recovery crystallization reactor, the sludge discharge port of the precipitation zone of the secondary reaction pool and the crystal discharge port of the phosphorus recovery crystallization reactor, the control system controls each valve to realize regular and quantitative crystal and sludge discharge, and the control system further controls the operation of the first dewatering device, the filter press, the filter press, the first wastewater lifting pump, the second wastewater lifting pump, the first dosing pump, the second dosing pump, the third dosing pump, the fourth dosing pump and the fifth dosing pump, the control system can control the flow of each dosing pump through the flow of the first and second wastewater lifting pumps and the real-time detection data of each pH meter, realize intelligent control of the reaction, and ensure sufficient resource treatment of fluorine and phosphorus.

Claims

1. A fractional reaction crystallization recovery process for semiconductor fluorine- and phosphorus-containing waste solutions, characterized by: It comprises the following steps: Step one: send the fluorine-containing and phosphorus-containing waste liquid into the fluorine recovery crystallization reactor, and send lime solution into the fluorine recovery crystallization reactor, control the pH of the mixed solution in the reactor to be 3-4, and the fluorine ion reacts with the calcium ion to form calcium fluoride crystals; Step two: the fluorine recovery crystallization reactor periodically and quantitatively discharges calcium fluoride crystals, and the discharged calcium fluoride crystals are dehydrated to obtain high-quality calcium fluoride crystal product; Step three: the filtrate produced when the fluorine recovery crystallization reactor in step one and the calcium fluoride crystals in step two are dehydrated is mixed and sent into the reaction area of the secondary reaction tank, and at the same time, lime solution and calcium chloride solution are added into the reaction area of the secondary reaction tank, the pH of the reaction area of the secondary reaction tank is controlled to be between 5-6, and the molar ratio of total calcium to fluorine is controlled to be between 0.5-0.6, the residual fluorine ion in the waste water reacts with the phosphate ion and the calcium ion to generate calcium fluoride and fluorapatite, and the residual fluorine ion is removed; Step four: the effluent of the reaction area of the secondary reaction tank enters the coagulation and sedimentation area of the secondary reaction tank, and PAC and PAM are added into the coagulation and sedimentation area of the secondary reaction tank for coagulation, flocculation and sedimentation treatment to remove calcium fluoride, fluorapatite, silicon dioxide and silicon aluminum precipitates in the waste water; Step five: the effluent of the coagulation and sedimentation area of the secondary reaction tank enters the phosphorus recovery crystallization reactor, and lime solution and calcium chloride solution are added into the phosphorus recovery crystallization reactor, the pH of the mixed solution in the phosphorus recovery crystallization reactor is controlled to be between 7-8, and the molar ratio of total calcium to phosphorus is controlled to be between 1.67-1.85, the calcium ion combines with the phosphorus and hydroxyl ion in the waste water to generate hydroxyapatite crystals, and the fluorine and phosphorus contents in the effluent of the phosphorus recovery crystallization reactor meet the discharge requirements; Step six: the phosphorus recovery crystallization reactor periodically and quantitatively discharges hydroxyapatite crystals, and the hydroxyapatite crystals are dehydrated to obtain calcium hydroxyphosphate crystal product.

2. The fractional reaction crystallization recovery process of semiconductor fluorine- and phosphorus-containing waste solutions according to claim 1, characterized in that: The fluorine-containing waste water is first sent into the fluorine-containing waste water conditioning tank for homogenization treatment before entering the fluorine recovery crystallization reactor, the lime solid is stirred and configured in the lime tank at a concentration of 2%-5%, and the calcium chloride solution with a concentration of 5%-10% is prepared in the calcium chloride tank.

3. The fractional reaction crystallization recovery process of semiconductor fluorine- and phosphorus-containing waste solutions according to claim 1, characterized in that: The coagulation and sedimentation area of the secondary reaction tank periodically discharges chemical sludge containing calcium fluoride, a small amount of fluorapatite, silicon dioxide and silicon aluminum precipitates, and the chemical sludge is formed into waste solid after pressure filtration treatment.

4. The fractional reaction crystallization recovery process of semiconductor fluorine- and phosphorus-containing waste solutions according to claim 3, characterized in that: The effluent of the fluorine recovery crystallization reactor, the filtrate produced when the calcium fluoride crystals are dehydrated, and the pressure filtration liquid produced by pressure filtration treatment of the chemical sludge discharged from the coagulation and sedimentation area of the secondary reaction tank are respectively sent into the primary effluent conditioning tank, and homogenization treatment is carried out in the primary effluent conditioning tank, and the effluent of the primary effluent conditioning tank enters the secondary reaction tank.

5. The fractional reaction crystallization recovery process of semiconductor fluorine- and phosphorus-containing waste solutions according to claim 1, characterized in that: The effluent of the coagulation and sedimentation area of the secondary reaction tank and the filtrate produced by dehydrating the hydroxyapatite crystals in step six are sent into the secondary effluent conditioning tank for homogenization treatment, and the effluent of the secondary effluent conditioning tank enters the phosphorus recovery crystallization reactor.

6. The fractional reaction crystallization recovery process of semiconductor fluoro- phosphated waste solutions according to claim 1, 4 or 5, characterized in that: The residence time of the fluorine-containing phosphorus-containing waste liquid and the lime solution in the fluorine recovery crystallization reactor is controlled to be 30-60 minutes; the total hydraulic residence time of the secondary reaction tank is 1-3 hours, and the fluorine ion concentration of the effluent of the coagulation sedimentation zone of the secondary reaction tank is lower than 8 mg / L; the reaction time of the waste water and the mixed solution of the lime solution and the calcium chloride solution in the phosphorus recovery crystallization reactor is 1-2 hours, and the phosphorus concentration in the effluent of the phosphorus recovery crystallization reactor is lower than 1 mg / L.

7. The fractional reaction crystallization recovery process of semiconductor fluorine- and phosphorus-containing waste solutions according to claim 1, characterized in that: The effluent of the phosphorus recovery crystallization reactor enters the subsequent treatment process of the plant area, is treated to reach the standard, and is discharged.

8. A semiconductor fluorine-containing phosphorus-containing waste liquid fractional reaction crystallization recovery system used in the semiconductor fluorine-containing phosphorus-containing waste liquid fractional reaction crystallization recovery process according to any one of claims 1 to 7, characterized by: The system comprises a fluorine-containing waste water adjusting tank, a lime tank, a calcium chloride tank, a fluorine recovery crystallization reactor, a first dewatering device, a secondary reaction tank, a filter press, a phosphorus recovery crystallization reactor, a second dewatering device, a first pH meter, a second pH meter, a third pH meter, a first waste water lifting pump, a second waste water lifting pump, a first dosing pump, a second dosing pump, a third dosing pump, a fourth dosing pump, a fifth dosing pump and a control system, the first waste water lifting pump can pump the fluorine-containing phosphorus-containing waste liquid in the fluorine-containing waste water adjusting tank into the fluorine recovery crystallization reactor, the first dosing pump, the second dosing pump and the third dosing pump can pump the lime solution in the lime tank into the fluorine recovery crystallization reactor, the reaction zone of the secondary reaction tank and the phosphorus recovery crystallization reactor respectively, the fourth dosing pump and the fifth dosing pump can pump the calcium chloride solution in the calcium chloride tank into the reaction zone of the secondary reaction tank and the phosphorus recovery crystallization reactor respectively, the first pH meter, the second pH meter and the third pH meter can detect the pH value of the mixed solution in the fluorine recovery crystallization reactor, the reaction zone of the secondary reaction tank and the phosphorus recovery crystallization reactor respectively in real time, and the first pH meter, the second pH meter and the third pH meter can transmit the detection data to the control system, the effluent outlet of the fluorine recovery crystallization reactor can enter the reaction zone of the secondary reaction tank through a pipeline, the crystal discharge outlet of the fluorine recovery crystallization reactor is connected with the first dewatering device through a pipeline, the secondary reaction tank further comprises a coagulation zone, a flocculation zone and a sedimentation zone, the reaction zone, the coagulation zone, the flocculation zone and the sedimentation zone of the secondary reaction tank are sequentially connected, the waste water after sufficient reaction in the reaction zone sequentially enters the coagulation zone, the flocculation zone and the sedimentation zone to perform coagulation reaction, flocculation reaction and sedimentation and water separation, the effluent of the sedimentation zone of the secondary reaction tank can be sent into the phosphorus recovery crystallization reactor by the second waste water lifting pump through a pipeline, the crystal discharge outlet of the phosphorus recovery crystallization reactor is connected with the second dewatering device through a pipeline, and the sludge discharge outlet of the sedimentation zone of the secondary reaction tank is connected with the filter press through a pipeline, the first dewatering device and the second dewatering device can respectively dewater the calcium fluoride crystal and the hydroxyapatite crystal, the filter press can filter the chemical sludge discharged from the sedimentation zone of the secondary reaction tank to form waste solid, and the control system controls the operation of the first dewatering device, the filter press, the filter press, the first waste water lifting pump, the second waste water lifting pump, the first dosing pump, the second dosing pump, the third dosing pump, the fourth dosing pump and the fifth dosing pump.

9. The fractional reaction crystallization recovery system of semiconductor fluorine-containing phosphorus-containing waste liquid according to claim 8, characterized in that: The fluorine recovery crystallization reactor outlet is communicated with the water inlet of the first-stage water regulating tank through a pipeline, and the fluorine recovery crystallization reactor outlet water flows into the first-stage water regulating tank; the filter liquid tanks of the first dewatering device and the filter press are also communicated with the water inlet of the first-stage water regulating tank through a pipeline; the first filter liquid conveying pump and the second filter liquid conveying pump can respectively pump the filter liquid in the filter liquid tanks of the first dewatering device and the filter press into the first-stage water regulating tank; the water outlet of the first-stage water regulating tank is communicated with the reaction zone of the secondary reaction tank through a pipeline; the sedimentation zone water outlet of the secondary reaction tank is communicated with the water inlet of the second-stage water regulating tank through a pipeline, and the sedimentation zone water of the secondary reaction tank flows into the second-stage water regulating tank; the filter liquid tank of the second dewatering device is communicated with the water inlet of the second-stage water regulating tank through a pipeline; the third filter liquid conveying pump can pump the filter liquid in the filter liquid tank of the second dewatering device into the second-stage water regulating tank; the water outlet of the second-stage water regulating tank is communicated with the water inlet of the phosphorus recovery crystallization reactor through a pipeline; the first-stage water regulating tank, the second-stage water regulating tank and the fluorine-containing wastewater regulating tank are each provided with a stirrer, and the stirrer can stir and homogenize the liquid in the first-stage water regulating tank, the second-stage water regulating tank and the fluorine-containing wastewater regulating tank.

10. The fractional reaction crystallization recovery process of semiconductor fluoro- phosphorous waste liquid according to claim 8, characterized in that: The lime tank and the calcium chloride tank are each provided with a medicament stirrer, the medicament stirrer can respectively stir the lime solution in the lime tank and the calcium chloride solution in the calcium chloride tank, and a coagulant dosing device and a flocculant dosing device are further arranged; the control system can control the coagulant dosing device and the flocculant dosing device to quantitatively add coagulant and flocculant to the coagulation zone and the flocculation zone of the secondary reaction tank; the control valves are arranged at the crystal discharge port of the fluorine recovery crystallization reactor, the sludge discharge port of the sedimentation zone of the secondary reaction tank and the crystal discharge port of the phosphorus recovery crystallization reactor, and the control system controls the valves to realize periodic and quantitative crystal and sludge discharge.

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