System and method for producing calcium fluoride particles using fluoride-containing wastewater

Abstract

The invention discloses a system and method for producing calcium fluoride particles by using fluorine-containing wastewater. The system comprises a fluidized bed crystallizer for reacting the fluorine-containing wastewater with a precipitant to generate calcium fluoride crystals, a drainage device for preliminarily separating the calcium fluoride crystal particles discharged from the fluidized bed crystallizer from water, a dehydrator for dehydrating the calcium fluoride crystal particles after drainage, and a control system for controlling the operation of various mechanisms. The method comprises the following steps: firstly adjusting the fluorine ion concentration in the fluorine-containing wastewater to below 500ppm and the calcium ion concentration in the precipitant to 18000ppm, then reacting and crystallizing the fluorine-containing wastewater and the precipitant in the fluidized bed crystallizer, draining and dehydrating the calcium fluoride crystal particles to reach a solid content of more than 95%, and finally packaging them by a finished product packaging machine. The calcium fluoride particles of the invention have a fast growth rate, are full and neat, and have a stable solid content of more than 95%, thereby improving production efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular to a system and method for producing calcium fluoride particles by utilizing fluorine-containing wastewater. Background Art

[0002] In industry, the treatment of fluoride-containing wastewater uses coagulation and sedimentation, which uses calcium-containing precipitants such as lime to convert fluoride ions in the wastewater into calcium fluoride. Since excessive calcium salts or calcium alkalis need to be added, the resulting calcium fluoride is often muddy and of low purity, making it impossible to realize resource utilization.

[0003] The use of fluidized bed crystallization reactor in the treatment of fluoride-containing wastewater can enhance the mass transfer effect in the calcium fluoride crystallization process, reduce the use of precipitants, homogenize the supersaturation in the reactor, increase the probability of solute collision on the seed surface, reduce the occurrence of secondary nucleation, and thus increase the particle size and purity of calcium fluoride crystals. The obtained particle size of calcium fluoride can reach a purity of more than 93%, and its resource application is more extensive.

[0004] As a primary treatment equipment for fluoride-containing wastewater, the traditional fluidized bed crystallizer usually only carries out simple packaging and drainage for the calcium fluoride crystallized therein. The water content of the calcium fluoride particles is high and unstable, and is not suitable as a by-product. Summary of the invention

[0005] In order to overcome the above-mentioned defects, the present invention provides a system and method for producing calcium fluoride particles using fluoride-containing wastewater. The system for producing calcium fluoride particles using fluoride-containing wastewater can produce calcium fluoride particles with low water content and stability.

[0006] The present invention adopts a technical solution to solve its technical problems: a system for producing calcium fluoride particles by using fluorine-containing wastewater, comprising a fluidized bed crystallizer, a drainage device, a dehydrator and a control system, wherein a reaction chamber for reacting fluorine-containing wastewater with a precipitant is provided in the fluidized bed crystallizer, a wastewater inlet and a precipitant feed inlet are provided on the side wall of the reaction chamber, a crystal discharge outlet is also provided at the lower end of the reaction chamber, the crystal discharge outlet at the lower end of the fluidized bed crystallizer is connected with a sand inlet of the drainage device through a pipeline, the drainage device can preliminarily separate calcium fluoride crystal particles from water and discharge them into the dehydrator, the dehydrator can perform centrifugal dehydration treatment on the calcium fluoride crystal particles, and the control system controls the operation of the fluidized bed crystallizer, the drainage device and the dehydrator.

[0007] As a further improvement of the present invention, a fluorine-containing wastewater regulating tank, a washing water temporary storage tank, a fluorine-containing wastewater delivery pump and a washing water delivery pump are also provided. The washing water separated from the calcium fluoride crystal particles in the drainage device can be discharged into the washing water temporary storage tank. The washing water temporary storage tank is connected to the fluorine-containing wastewater regulating tank through a pipeline. The washing water delivery pump can pump the washing water in the washing water temporary storage tank into the fluorine-containing wastewater regulating tank. The fluorine-containing wastewater regulating tank is also provided with an initial fluorine-containing wastewater inlet for supplying initial fluorine-containing wastewater and a water discharge port for discharging the prepared fluorine-containing wastewater. The fluorine-containing wastewater discharge outlet is connected to the wastewater inlet of the fluidized bed crystallizer. The fluorine-containing wastewater delivery pump can pump the fluorine-containing wastewater prepared in the fluorine-containing wastewater regulating tank into the reaction chamber of the fluidized bed crystallizer. The fluorine-containing wastewater regulating tank is provided with a fluorine ion concentration detection device, which can detect the fluorine ion concentration in the wastewater in the fluorine-containing wastewater regulating tank. The fluorine ion concentration detection device is electrically connected and communicated with the control system, and the control system controls the start and stop of the fluorine-containing wastewater delivery pump and the washing water delivery pump.

[0008] As a further improvement of the present invention, the fluorine-containing wastewater regulating tank is further provided with an agitator, a first pH value monitoring device and a first liquid level meter. The agitator can stir the fluorine-containing wastewater in the fluorine-containing wastewater regulating tank. The first pH value monitoring device and the first liquid level meter are respectively electrically connected and communicated with the control system. A first pH value regulator feed bin and a first pH feed pump are also provided. The first pH value regulator feed bin is connected to the fluorine-containing wastewater regulating tank through a pipeline. The first pH feed pump can pump the pH value regulator into the fluorine-containing wastewater regulating tank. An inlet valve is also provided on the initial fluorine-containing wastewater inlet of the fluorine-containing wastewater regulating tank. The control system controls the start and stop actions of the first PH feed pump and the inlet valve.

[0009] As a further improvement of the present invention, the drainage device is a sand-water separator or a cyclone.

[0010] As a further improvement of the present invention, a precipitant dilution barrel and a precipitant dosing pump are further provided. A precipitant solution feed port and a precipitant solution discharge port are provided on the side wall of the precipitant dilution barrel. The precipitant and water can enter the precipitant dilution barrel through the precipitant solution feed port, respectively. A precipitant agitator and a calcium ion concentration detection device are provided in the precipitant dilution barrel. The precipitant agitator can stir the precipitant solution in the precipitant dilution barrel. The calcium ion concentration detection device can detect the calcium ion concentration in the precipitant dilution barrel. The calcium ion concentration detection device is electrically connected and communicated with the control system. The precipitant solution discharge port is connected with the precipitant feed port of the fluidized bed crystallizer through a pipeline. The precipitant dosing pump can pump the precipitant solution in the precipitant dilution barrel into the fluidized bed crystallizer. The control system can control the dosage of the precipitant and water and the start and stop feeding of the precipitant dosing pump.

[0011] As a further improvement of the present invention, a buffer silo and a screw feeder are further provided, the sand discharge port of the drainage device is directly connected to the feed port of the buffer silo, the bottom of the buffer silo is connected to the feed port of the screw feeder, the discharge port of the screw feeder is connected to the feed port of the dehydrator, and a rotary resistance level meter is provided in the buffer silo. The rotary resistance level meter can sense the material level height of the calcium fluoride particles that have undergone primary dehydration in the buffer silo, the rotary resistance level meter is electrically connected and communicated with the control system, and the control system controls the start and stop of the screw feeder.

[0012] As a further improvement of the present invention, a stacking conveying mechanism and a finished product packaging machine are also provided. The feed end of the stacking conveying mechanism is connected to the discharge end of the dehydrator, and the discharge end of the stacking conveying mechanism is connected to the feed port of the finished product packaging machine. The stacking conveying mechanism can feed the calcium fluoride particles dehydrated by the dehydrator into the finished product packaging machine, and the finished product packaging machine can quantitatively package the calcium fluoride particles.

[0013] As a further improvement of the present invention, the fluidized bed crystallizer includes a main reaction chamber, a reflux water distribution chamber, a precipitant distribution pipe, a fluorine-containing wastewater distribution pipe and a reflux pump. The main reaction chamber and the reflux water distribution chamber are connected from top to bottom. The wastewater inlet and the precipitant feed port are respectively located on the side wall of the main reaction chamber. The upper end of the main reaction chamber is also provided with a drain port and a reflux water outlet. A plurality of fluorine-containing wastewater distribution pipes extending in the vertical direction are fixedly installed in the main reaction chamber. Each fluorine-containing wastewater distribution pipe is connected to the wastewater inlet through a pipeline. The lower end of the fluorine-containing wastewater distribution pipe is connected to the reflux water distribution chamber. A plurality of water distribution holes are provided on the side wall of the fluorine-containing wastewater distribution pipe at intervals in the vertical direction. The precipitant distribution pipe extending in the vertical direction is fixedly installed in the main reaction chamber. The medicine distribution holes correspond to the water distribution holes on the fluorine-containing wastewater distribution pipe, the reflux water distribution chamber is a truncated cone structure with an inner diameter at the upper end larger than the inner diameter at the lower end, the crystal discharge port is located at the lower end of the reflux water distribution chamber, the side wall of the reflux water distribution chamber in the circumferential direction is a double-layer structure with a hollow inner cavity, a reflux water distributor connected to the internal space of the reflux water distribution chamber is formed on the inner side wall in the circumferential direction of the reflux water distribution chamber, a reflux water inlet connected to the hollow inner cavity is formed on the outer side wall in the circumferential direction of the reflux water distribution chamber, the water inlet direction of the reflux water inlet is horizontally tangent to the side wall of the reflux water distribution chamber, the reflux water inlet is connected to the reflux water outlet located at the upper end of the main reaction chamber through a pipeline, and the reflux pump pumps the biochemical treatment water discharged from the reflux water outlet into the hollow inner cavity of the side wall of the reflux water distribution chamber.

[0014] As a further improvement of the present invention, a pressure transmitter and a control valve are fixedly installed on the crystal discharge outlet of the fluidized bed crystallizer, and the pressure transmitter can sense the pressure exerted on it by the calcium fluoride particles located at the crystal discharge outlet. The pressure transmitter is electrically connected and communicates with the control system, and the control system controls the control valve on the crystal discharge outlet to open to discharge the calcium fluoride particles.

[0015] A method for producing calcium fluoride particles from fluoride-containing wastewater, the specific steps are as follows:

[0016] Step 1: The fluoride-containing wastewater is regulated in the fluoride-containing wastewater regulating tank to control the fluoride ion concentration below 500ppm, and the precipitant is diluted in the precipitant dilution tank to form a precipitant solution, and the calcium ion concentration in the precipitant solution is controlled to be diluted to 18000ppm;

[0017] Step 2: Pump the prepared fluorine-containing wastewater in the fluorine-containing wastewater regulating tank and the diluted precipitant solution in the precipitant dilution tank into the fluidized bed crystallizer respectively, and the fluoride ions in the fluorine-containing wastewater react with the calcium ions in the precipitant in the main reaction zone of the fluidized bed crystallizer to produce calcium fluoride;

[0018] Step 3: Calcium fluoride is crystallized on the initial seed crystal in the fluidized bed crystallizer, and the calcium fluoride particles are discharged from the crystal discharge port of the fluidized bed crystallizer after reaching the requirements;

[0019] Step 4: The mixture of calcium fluoride particles and water enters the drainage device. After the drainage device completes the primary dehydration and cleaning of the calcium fluoride particles, the calcium fluoride particles are piled in the buffer silo;

[0020] Step 5: The calcium fluoride particles in the buffer silo are fed into a centrifugal dehydrator through a centrifugal feeding screw mechanism for secondary dehydration treatment;

[0021] Step 6: After the centrifugal dehydrator completes the secondary dehydration of the calcium fluoride particles, the solid content of the calcium fluoride particles is controlled to be stable above 95%. The calcium fluoride particles after the secondary dehydration are transported to the finished product packaging machine through the stacking conveying mechanism to complete the packaging.

[0022] The beneficial effects of the present invention are as follows: the fluidized bed crystallizer of the present invention is provided with a truncated cone-shaped reflux water distribution cavity with a hollow cavity as the side wall, so that the reflux water enters tangentially, solid-liquid separation is performed in advance, the tiny particles in the reflux water are reduced, and the growth of calcium fluoride generated by the new reaction on the tiny particles is reduced, thereby accelerating the growth rate of calcium fluoride particles; the control condition for discharging crystals from the fluidized bed crystallizer can be determined according to the indication of the pressure transmitter at the bottom, so as to prevent the calcium fluoride particles from being discharged before they grow up; two-stage dehydration is performed by a drainage device and a dehydrator, the primary dehydration treatment volume is large, and the secondary dehydration uses a centrifugal dehydrator, so that the moisture content of the product is greatly reduced and stable, and efficient and stable dehydration treatment is achieved, and finally calcium fluoride particles with a solid content stable at more than 95% are obtained; the present invention also provides a buffer silo, which connects different operation systems and equipment treatment volumes at both ends, effectively reduces equipment investment, reduces equipment investment costs, and improves production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a process flow chart of the present invention;

[0024] Figure 2 It is a three-dimensional diagram of the system structure of the present invention;

[0025] Figure 3 This is the front view of the system structure of the present invention;

[0026] Figure 4 It is a three-dimensional diagram of the fluidized bed crystallizer of the present invention;

[0027] Figure 5 It is a front view of the fluidized bed crystallizer of the present invention;

[0028] Figure 6 A top view of the fluidized bed crystallizer of the present invention;

[0029] Figure 7 It is a three-dimensional exploded view of the fluidized bed crystallizer of the present invention;

[0030] Figure 8 for Figure 7 Enlarged view of part A in the middle;

[0031] Fig. 9 for Figure 7 Enlarged view of middle part B;

[0032] Fig.10 This is the main view of the fluorine-containing wastewater distribution pipe;

[0033] Fig.11 This is a top view of the fluorine-containing wastewater distribution pipe. DETAILED DESCRIPTION

[0034] Embodiment: A system for producing calcium fluoride particles using fluorine-containing wastewater comprises a fluidized bed crystallizer 200, a drainage device 510, a dehydrator 560 and a control system. A reaction chamber for reacting fluorine-containing wastewater with a precipitant is provided in the fluidized bed crystallizer 200. A wastewater inlet and a precipitant feed inlet are provided on the side wall of the reaction chamber. A crystal discharge port 244 is also provided at the lower end of the reaction chamber. The crystal discharge port 244 at the lower end of the fluidized bed crystallizer 200 is connected to a sand inlet of the drainage device 510 through a pipeline. The drainage device 510 can preliminarily separate calcium fluoride crystal particles from water and discharge them into the dehydrator 560. The dehydrator 560 can perform centrifugal dehydration treatment on the calcium fluoride crystal particles. The control system controls the operation of the fluidized bed crystallizer 200, the drainage device 510 and the dehydrator 560.

[0035] After the fluorine-containing wastewater reacts to generate calcium fluoride through the fluidized bed crystallizer 200, calcium fluoride particles are formed through crystallization. The calcium fluoride particles are discharged through the crystal discharge port 244 of the fluidized bed crystallizer 200. A portion of the wastewater in the fluidized bed crystallizer is also discharged together with the calcium fluoride. The wastewater and the calcium fluoride particles enter the drainage device 510 for dehydration and cleaning, so as to preliminarily separate the calcium fluoride particles with a solid mass concentration of 20% from water and complete the preliminary dehydration. At the same time, the cleaning of the calcium fluoride particles is also completed. At this time, the water content of the calcium fluoride particles is about 80%. The calcium fluoride particles that have undergone preliminary dehydration enter the dehydrator 560 for secondary dehydration. The dehydrator 560 dehydrates the calcium fluoride particles through centrifugal force to further reduce its water content and make the solid content reach more than 95%, so that it can be used as a by-product of fluorine-containing wastewater treatment and recycled, thereby realizing the resource treatment of fluorine-containing wastewater.

[0036] The fluorine-containing wastewater regulating tank 110, the washing water temporary storage tank 520, the fluorine-containing wastewater delivery pump 120 and the washing water delivery pump 530 are also provided. The washing water separated from the calcium fluoride crystal particles in the drainage device 510 can be discharged into the washing water temporary storage tank 520. The washing water temporary storage tank 520 is connected with the fluorine-containing wastewater regulating tank 110 through a pipeline. The washing water delivery pump 530 can pump the washing water in the washing water temporary storage tank 520 into the fluorine-containing wastewater regulating tank 110. The fluorine-containing wastewater regulating tank 110 is also provided with an initial fluorine-containing wastewater inlet for supplying initial fluorine-containing wastewater and a discharge port for discharging the prepared fluorine-containing wastewater. The fluorine-containing wastewater discharge outlet is connected to the wastewater inlet of the fluidized bed crystallizer 200, and the fluorine-containing wastewater delivery pump 120 can pump the fluorine-containing wastewater prepared in the fluorine-containing wastewater regulating tank 110 into the reaction chamber of the fluidized bed crystallizer 200. The fluorine-containing wastewater regulating tank 110 is provided with a fluorine ion concentration detection device, which can detect the fluorine ion concentration in the wastewater in the fluorine-containing wastewater regulating tank 110. The fluorine ion concentration detection device is electrically connected and communicated with the control system, and the control system controls the start and stop of the fluorine-containing wastewater delivery pump 120 and the washing water delivery pump 530.

[0037] Before the fluorine-containing wastewater enters the fluidized bed crystallizer 200 for reaction, it first enters the fluorine-containing wastewater regulating tank 110 for fluorine ion concentration adjustment. The fluorine ion concentration in the fluorine-containing wastewater is reduced to below 500 ppm by adding washing water from which calcium fluoride has been removed into the fluorine-containing wastewater regulating tank 110. When the fluorine ion concentration in the fluorine-containing wastewater is lower than 500 ppm, the washing water delivery pump 530 stops supplying washing water to the fluorine-containing wastewater regulating tank 110, thereby maintaining the fluorine ion concentration of the fluorine-containing wastewater in the fluorine-containing wastewater regulating tank 110 within a balanced numerical range, which is conducive to the fluorine ions fully reacting with the precipitant in the fluidized bed crystallizer 200 and rapidly crystallizing.

[0038] The fluorine-containing wastewater regulating tank 110 is also provided with an agitator, a first pH value monitoring device and a first liquid level meter. The agitator can stir the fluorine-containing wastewater in the fluorine-containing wastewater regulating tank 110. The first pH value monitoring device and the first liquid level meter are electrically connected and communicated with the control system respectively. A first pH value regulator feed bin and a first pH feed pump are also provided. The first pH value regulator feed bin is connected to the fluorine-containing wastewater regulating tank 110 through a pipeline. The first pH feed pump can pump the pH value regulator into the fluorine-containing wastewater regulating tank 110. An inlet valve is also provided on the initial fluorine-containing wastewater inlet of the fluorine-containing wastewater regulating tank 110. The control system controls the start and stop actions of the first pH feed pump and the inlet valve. The fluorine-containing wastewater in the fluorine-containing wastewater regulating tank 110 is stirred by an agitator to ensure that fluorine ions in the fluorine-containing wastewater are evenly distributed, thereby accurately obtaining real data on the fluorine ion concentration, and the pH value and liquid level of the fluorine-containing wastewater in the fluorine-containing wastewater regulating tank 110 are monitored in real time by a first pH value monitoring device and a first liquid level meter to prevent the pH value of the fluorine-containing wastewater from exceeding the standard and affecting the chemical reaction in the fluidized bed crystallizer 200, and to prevent the liquid level in the fluorine-containing wastewater regulating tank 110 from being too high and overflowing.

[0039] The drainage device 510 is a sand-water separator or a cyclone. The calcium fluoride and the biochemical treatment water are initially separated by the sand-water separator or the cyclone. In addition, the calcium fluoride can also be initially dehydrated by a filter screen, etc. These are equivalent replacement structures that can be easily thought of by those skilled in the art based on this application and fall within the scope of protection of this patent.

[0040] A precipitant dilution barrel 130 and a precipitant dosing pump 140 are also provided. A precipitant solution feed port and a precipitant solution discharge port are provided on the side wall of the precipitant dilution barrel 130. The precipitant and water can enter the precipitant dilution barrel 130 through the precipitant solution feed port respectively. A precipitant agitator and a calcium ion concentration detection device are provided in the precipitant dilution barrel 130. The precipitant agitator can stir the precipitant solution in the precipitant dilution barrel 130. The calcium ion concentration detection device can detect the calcium ion concentration in the precipitant dilution barrel 130. The calcium ion concentration detection device is electrically connected and communicated with the control system. The precipitant solution discharge port is connected with the precipitant feed port of the fluidized bed crystallizer 200 through a pipeline. The precipitant dosing pump 140 can pump the precipitant solution in the precipitant dilution barrel 130 into the fluidized bed crystallizer 200. The control system can control the dosage of the precipitant and water and the start and stop of the precipitant dosing pump 140. The precipitant is made into a precipitant solution with a calcium ion concentration of about 18000 ppm by the precipitant dilution barrel 130, so that the precipitant and fluoride ions can react chemically to generate calcium fluoride.

[0041] A buffer bin 540 and a screw feeder 550 are also provided. The sand discharge port of the drainage device 510 is directly connected to the feed port of the buffer bin 540. The bottom of the buffer bin 540 is connected to the feed port of the screw feeder 550. The discharge port of the screw feeder 550 is connected to the feed port of the dehydrator 560. A rotary level meter is provided in the buffer bin 540. The rotary level meter can sense the material level of the calcium fluoride particles that have undergone primary dehydration in the buffer bin 540. The rotary level meter is electrically connected and communicated with the control system, and the control system controls the start and stop of the screw feeder 550. The drainage device 510 discharges the calcium fluoride particles that have undergone primary dehydration into the buffer bin for temporary storage, and then the screw feeder 550 sends the calcium fluoride particles that have undergone primary dehydration into the dehydrator 560 for dehydration. The buffer bin 540 connects different operating systems and equipment processing capacities at both ends to achieve flexible buffer feeding and reduce equipment investment.

[0042] A stacking conveying mechanism 570 and a finished product packaging machine 580 are also provided. The feeding end of the stacking conveying mechanism 570 is connected to the discharging end of the dehydrator 560, and the discharging end of the stacking conveying mechanism 570 is connected to the feeding port of the finished product packaging machine 580. The stacking conveying mechanism 570 can feed the calcium fluoride particles dehydrated by the dehydrator 560 into the finished product packaging machine 580, and the finished product packaging machine 580 can quantitatively package the calcium fluoride particles. The stacking conveying mechanism 570 and the finished product packaging machine 580 are provided to realize automatic quantitative packaging of the calcium fluoride particles, which is conducive to realizing fully automated production and packaging, reducing manual labor intensity, and reducing manual packaging costs.

[0043] The fluidized bed crystallizer 200 includes a main reaction chamber 210, a reflux water distribution chamber 240, a precipitant distribution pipe 230, a fluorine-containing wastewater distribution pipe 220 and a reflux pump 310. The main reaction chamber 210 and the reflux water distribution chamber 240 are connected from top to bottom. The wastewater inlet and the precipitant feed port are respectively located on the side wall of the main reaction chamber 210. The upper end of the main reaction chamber 210 is also provided with a drain port 214 and a reflux water outlet 213. A plurality of vertically extending The fluorine-containing wastewater distribution pipe 220 is fixedly installed in the main reaction chamber 210, and each fluorine-containing wastewater distribution pipe 220 is connected to the wastewater inlet through a pipeline. The lower end of the fluorine-containing wastewater distribution pipe 220 is connected to the reflux water distribution chamber 240. A plurality of water distribution holes are arranged on the side wall of the fluorine-containing wastewater distribution pipe 220 at intervals in the vertical direction. The precipitant distribution pipe 230 extending in the vertical direction is fixedly installed in the main reaction chamber 210. The precipitant distribution pipe 230 is provided with a precipitant distribution pipe 230 connected to the fluorine-containing wastewater. The water distribution holes on the distribution pipe 220 correspond to the medicine distribution holes, the reflux water distribution chamber 240 is a truncated cone structure with an inner diameter at the upper end larger than the inner diameter at the lower end, the crystal discharge port 244 is located at the lower end of the reflux water distribution chamber 240, the circumferential side wall of the reflux water distribution chamber 240 is a double-layer structure with a hollow inner cavity 242, and a reflux water distributor 243 connected to the internal space of the reflux water distribution chamber 240 is formed on the inner side wall of the circumferential direction of the reflux water distribution chamber 240. A reflux water inlet 241 connected to the hollow inner cavity 242 is formed on the outer side wall in the circumferential direction of 240. The water inlet direction of the reflux water inlet 241 is horizontally tangent to the side wall of the reflux water distribution chamber 240. The reflux water inlet 241 is connected to the reflux water outlet 213 located at the upper end of the main reaction chamber 210 through a pipeline. The reflux pump 310 pumps the biochemical treatment water discharged from the reflux water outlet 213 into the hollow inner cavity 242 of the side wall of the reflux water distribution chamber 240.

[0044] The main reaction chamber 210 is composed of a water outlet 212 whose upper inner diameter is larger than that of the lower inner diameter and a cylindrical shell 211 of the main reaction chamber 210. The fluorine-containing wastewater distribution pipe 220 includes a fluorine-containing wastewater inlet pipe 221 located on the shell of the cylindrical main reaction chamber 210, a circular main distribution pipe 224 installed on the inner side wall of the shell of the cylindrical main reaction chamber 210, and an axial distribution pipe 222 extending in the vertical direction, wherein the circular main distribution pipe is connected to the fluorine-containing wastewater inlet pipe, and a plurality of axial distribution pipes 222 are connected to the fluorine-containing wastewater inlet pipe. The distribution pipe 222 is vertically cross-connected with the annular main distribution pipe, and a plurality of axial distribution pipes 222 are evenly spaced to surround a circular space. The water distribution hole is located on the axial distribution pipe, and a horizontal distribution nozzle 223 is preferably provided on the water distribution hole, so that the fluorine-containing wastewater enters the annular main distribution pipe 224 through the fluorine-containing wastewater inlet pipe 221, and then evenly enters the fluorine-containing wastewater distribution pipe 220220, and finally evenly enters the main reaction chamber 210 through the horizontal distribution nozzle 223;

[0045] The precipitant distribution pipe 230 includes a horizontal drug feed pipe 231 arranged on the outer shell of the cylindrical main reaction chamber 210 and a vertical drug feed pipe located on the axis of the main reaction chamber 210. The horizontal drug feed pipe is connected to the lower end of the vertical drug feed pipe. The drug distribution hole is on the side wall of the vertical drug feed pipe. An umbrella-shaped distributor 232 is preferably installed on the drug distribution hole. The precipitant enters the vertical drug feed pipe through the horizontal drug feed pipe 231, and then enters the main reaction zone through the umbrella-shaped distributor 232. The umbrella-shaped distributor 232 is preferably arranged in a one-to-one correspondence with the horizontal distribution nozzle 223.

[0046] Fluoride-containing wastewater and precipitant react chemically in the main reaction chamber 210 to generate calcium fluoride. Under the fluidized bed conditions provided by the reflux water distribution chamber 240, calcium fluoride crystallizes on the initial seed crystals. The water after the reaction is discharged through the drain port 214 at the upper end of the main reaction chamber 210, and the grown crystals are discharged through the crystal discharge port 244. Since the fluidized bed crystallizer 200 has a reflux water distribution chamber 240 with a hollow cavity structure, the reflux water enters from a tangential direction. Thanks to its cyclone-like frustum cone structure, the calcium fluoride solid particles will rotate along the outer side of the cavity and gradually gather at the bottom under the action of centrifugal force, which can effectively reduce the solids in the reflux water from entering the reaction zone, reduce the possibility of solids blocking the reflux water distributor 243, and improve the crystallization efficiency of the fluidized bed crystallizer 200.

[0047] A pressure transmitter and a control valve are fixedly installed on the crystal discharge outlet 244 of the fluidized bed crystallizer 200. The pressure transmitter can sense the pressure exerted by the calcium fluoride particles at the crystal discharge outlet 244. The pressure transmitter is electrically connected and communicates with the control system. The control system controls the control valve on the crystal discharge outlet 244 to open to discharge the calcium fluoride particles. After 2-3 days of continuous operation of the fluidized bed crystallizer 200, as the calcium fluoride particles in the fluidized bed crystallizer 200 grow, the bottom pressure increases to twice the initial static pressure, and it can be considered that the crystal discharge condition is met. The control system sends an opening signal to the control valve to open the crystal discharge port 244, so that the calcium fluoride particles are discharged together with part of the wastewater. When the pressure transmitter senses that the pressure value decreases to the initial value, the control system sends a closing signal to the control valve, and the control valve closes the crystal discharge port 244. At this time, the calcium fluoride particles and wastewater in the fluidized bed crystallizer 200 cannot be discharged through the crystal discharge port 244. This structure ensures that the calcium fluoride particles grow large enough before being discharged, and prevents the discharge of small calcium fluoride particles, thereby ensuring that the final calcium fluoride particles are uniform and full without debris.

[0048] A method for producing calcium fluoride particles from fluoride-containing wastewater in a system for producing calcium fluoride particles from fluoride-containing wastewater, the specific steps are as follows:

[0049] Step 1: The fluorine-containing wastewater is regulated in the fluorine-containing wastewater regulating tank 110 to control the fluorine ion concentration to be below 500 ppm, and the precipitant is diluted in the precipitant dilution tank 130 to form a precipitant solution, and the calcium ion concentration in the precipitant solution is controlled to be diluted to 18000 ppm;

[0050] Step 2: Pump the prepared fluorine-containing wastewater in the fluorine-containing wastewater regulating tank 110 and the diluted precipitant solution in the precipitant dilution tank 130 into the fluidized bed crystallizer 200 respectively, and the fluorine ions in the fluorine-containing wastewater react with the calcium ions in the precipitant in the main reaction zone of the fluidized bed crystallizer 200 to produce calcium fluoride;

[0051] Step 3: Calcium fluoride is crystallized on the initial seed crystals in the fluidized bed crystallizer 200, and the calcium fluoride particles are discharged from the crystal discharge port 244 of the fluidized bed crystallizer 200 after reaching the required size;

[0052] Step 4: The mixture of calcium fluoride particles and water enters the drain device 510. After the drain device 510 completes primary dehydration and cleaning of the calcium fluoride particles, the calcium fluoride particles are stacked in the buffer silo 540.

[0053] Step 5: The calcium fluoride particles in the buffer silo 540 are fed into the centrifugal dehydrator 560 through a centrifugal feeding screw mechanism for secondary dehydration treatment;

[0054] Step 6: After the centrifugal dehydrator 560 completes secondary dehydration of the calcium fluoride particles, the solid content of the calcium fluoride particles is controlled to be stable above 95%. The calcium fluoride particles after secondary dehydration are transported to the finished product packaging machine 580 through the stacking conveying mechanism 570 to complete packaging.

Claims

1. A system for producing calcium fluoride particles using fluoride-containing wastewater, characterized in that: The invention comprises a fluidized bed crystallizer (200), a drainage device (510), a dehydrator (560) and a control system. The fluidized bed crystallizer is provided with a reaction chamber for reacting fluorine-containing wastewater with a precipitant. The side wall of the reaction chamber is provided with a wastewater inlet and a precipitant feed inlet. The lower end of the reaction chamber is also provided with a crystal discharge port (244). The crystal discharge port at the lower end of the fluidized bed crystallizer is connected to the sand inlet of the drainage device through a pipeline. The drainage device can perform preliminary separation of calcium fluoride crystal particles from water and discharge the separated particles into the dehydrator. The dehydrator can perform centrifugal dehydration on the calcium fluoride crystal particles. The control system controls the operation of the fluidized bed crystallizer, the drainage device and the dehydrator. The fluidized bed crystallizer comprises a main reaction chamber (210), a reflux water distribution chamber (240), a precipitant distribution pipe (230), a fluorine-containing wastewater distribution pipe (220) and a reflux pump (310). The main reaction chamber and the reflux water distribution chamber are connected from top to bottom. The wastewater inlet and the precipitant feed port are respectively located on the side wall of the main reaction chamber. A drain port (214) and a reflux water outlet (213) are also provided at the upper end of the main reaction chamber. A plurality of fluorine-containing wastewater distribution pipes extending in a vertical direction are fixed to the main reaction chamber. It is installed in the main reaction chamber, each fluorine-containing wastewater distribution pipe is connected with the wastewater inlet through a pipeline, the lower end of the fluorine-containing wastewater distribution pipe is connected with the reflux water distribution chamber, a plurality of water distribution holes are arranged on the side wall of the fluorine-containing wastewater distribution pipe at intervals in the vertical direction, and a precipitant distribution pipe extending in the vertical direction is fixedly installed in the main reaction chamber, and a precipitant distribution pipe is provided with a medicine distribution hole corresponding to the water distribution hole on the fluorine-containing wastewater distribution pipe. The reflux water distribution chamber is a truncated cone structure with an inner diameter of the upper end larger than that of the lower end, the crystal discharge port is located at the lower end of the reflux water distribution chamber, and the side wall of the reflux water distribution chamber in the circumferential direction is a A double-layer structure with a hollow inner cavity is provided, a reflux water distributor (243) connected to the internal space of the reflux water distribution cavity is formed on the inner side wall in the circumferential direction of the reflux water distribution cavity, and a reflux water inlet connected to the hollow inner cavity (242) is formed on the outer side wall in the circumferential direction of the reflux water distribution cavity. The water inlet direction of the reflux water inlet is horizontally tangent to the side wall of the reflux water distribution cavity. The reflux water inlet (241) is connected to the reflux water outlet located at the upper end of the main reaction cavity through a pipeline, and a reflux pump pumps the biochemical treatment water discharged from the reflux water outlet into the hollow inner cavity of the side wall of the reflux water distribution cavity.

2. The system for producing calcium fluoride particles using fluoride-containing wastewater according to claim 1, characterized in that: The invention also provides a fluorine-containing wastewater regulating tank (110), a washing water temporary storage tank (520), a fluorine-containing wastewater delivery pump (120) and a washing water delivery pump (530). The washing water from which calcium fluoride crystal particles are separated in the drainage device can be discharged into the washing water temporary storage tank. The washing water temporary storage tank is connected to the fluorine-containing wastewater regulating tank through a pipeline. The washing water delivery pump can pump the washing water in the washing water temporary storage tank into the fluorine-containing wastewater regulating tank. The fluorine-containing wastewater regulating tank is also provided with an initial fluorine-containing wastewater inlet for supplying initial fluorine-containing wastewater and a fluorine-containing wastewater delivery pump for transferring the prepared fluorine-containing wastewater into the fluorine-containing wastewater. A fluorine-containing wastewater discharge outlet is provided for fluorine-containing wastewater, and the fluorine-containing wastewater discharge outlet is connected with the wastewater inlet of the fluidized bed crystallizer. The fluorine-containing wastewater delivery pump can pump the fluorine-containing wastewater prepared in the fluorine-containing wastewater regulating tank into the reaction chamber of the fluidized bed crystallizer. A fluorine ion concentration detection device is provided in the fluorine-containing wastewater regulating tank. The fluorine ion concentration detection device can detect the fluorine ion concentration in the wastewater in the fluorine-containing wastewater regulating tank. The fluorine ion concentration detection device is electrically connected and communicated with the control system. The control system controls the start and stop of the fluorine-containing wastewater delivery pump and the washing water delivery pump.

3. The system for producing calcium fluoride particles using fluoride-containing wastewater according to claim 2, characterized in that: The fluorine-containing wastewater regulating tank is also provided with an agitator, a first pH value monitoring device and a first liquid level meter. The agitator can stir the fluorine-containing wastewater in the fluorine-containing wastewater regulating tank. The first pH value monitoring device and the first liquid level meter are electrically connected and communicated with the control system respectively. A first pH value regulator feed bin and a first pH feed pump are also provided. The first pH value regulator feed bin is connected to the fluorine-containing wastewater regulating tank through a pipeline. The first pH feed pump can pump the pH value regulator into the fluorine-containing wastewater regulating tank. An inlet valve is also provided on the initial fluorine-containing wastewater inlet of the fluorine-containing wastewater regulating tank. The control system controls the start and stop actions of the first pH feed pump and the inlet valve.

4. The system for producing calcium fluoride particles using fluoride-containing wastewater according to claim 1, characterized in that: The drainage device is a sand-water separator or a cyclone.

5. The system for producing calcium fluoride particles using fluoride-containing wastewater according to claim 1, characterized in that: A precipitant dilution barrel (130) and a precipitant dosing pump (140) are also provided. A precipitant solution feed port and a precipitant solution discharge port are provided on the side wall of the precipitant dilution barrel. The precipitant and water can enter the precipitant dilution barrel through the precipitant solution feed port, respectively. A precipitant agitator and a calcium ion concentration detection device are provided in the precipitant dilution barrel. The precipitant agitator can stir the precipitant solution in the precipitant dilution barrel. The calcium ion concentration detection device can detect the calcium ion concentration in the precipitant dilution barrel. The calcium ion concentration detection device is electrically connected and communicates with the control system. The precipitant solution discharge port is connected to the precipitant feed port of the fluidized bed crystallizer through a pipeline. The precipitant dosing pump can pump the precipitant solution in the precipitant dilution barrel into the fluidized bed crystallizer. The control system can control the dosage of the precipitant and water and the start and stop of the precipitant dosing pump.

6. The system for producing calcium fluoride particles using fluoride-containing wastewater according to claim 5, characterized in that: A buffer silo (540) and a screw feeder (550) are also provided. The sand discharge port of the drainage device is directly connected to the feed port of the buffer silo. The bottom of the buffer silo is connected to the feed port of the screw feeder. The discharge port of the screw feeder is connected to the feed port of the dehydrator. A rotary paddle level meter is provided in the buffer silo. The rotary paddle level meter can sense the material level height of the calcium fluoride particles that have undergone primary dehydration in the buffer silo. The rotary paddle level meter is electrically connected to the control system for communication. The control system controls the start and stop of the screw feeder.

7. The system for producing calcium fluoride particles using fluoride-containing wastewater according to claim 6, characterized in that: A stacking and conveying mechanism (570) and a finished product packaging machine (580) are also provided. The feed end of the stacking and conveying mechanism is connected to the discharge end of the dehydrator, and the discharge end of the stacking and conveying mechanism is connected to the feed port of the finished product packaging machine. The stacking and conveying mechanism can deliver the calcium fluoride particles dehydrated by the dehydrator into the finished product packaging machine, and the finished product packaging machine can quantitatively package the calcium fluoride particles.

8. The system for producing calcium fluoride particles using fluoride-containing wastewater according to claim 1, characterized in that: A pressure transmitter and a control valve are fixedly installed on the crystal discharge outlet of the fluidized bed crystallizer. The pressure transmitter can sense the pressure exerted on it by the calcium fluoride particles at the crystal discharge outlet. The pressure transmitter is electrically connected and communicates with the control system. The control system controls the control valve on the crystal discharge outlet to open to discharge the calcium fluoride particles.

9. A method for producing calcium fluoride particles from fluoride-containing wastewater using the system for producing calcium fluoride particles from fluoride-containing wastewater according to claim 7, characterized in that: The specific steps are as follows: Step 1: The fluoride-containing wastewater is regulated in the fluoride-containing wastewater regulating tank to control the fluoride ion concentration below 500ppm, and the precipitant is diluted in the precipitant dilution tank to form a precipitant solution, and the calcium ion concentration in the precipitant solution is controlled to be diluted to 18000ppm; Step 2: Pump the prepared fluorine-containing wastewater in the fluorine-containing wastewater regulating tank and the diluted precipitant solution in the precipitant dilution tank into the fluidized bed crystallizer respectively, and the fluoride ions in the fluorine-containing wastewater react with the calcium ions in the precipitant in the main reaction zone of the fluidized bed crystallizer to produce calcium fluoride; Step 3: Calcium fluoride is crystallized on the initial seed crystal in the fluidized bed crystallizer, and the calcium fluoride particles are discharged from the crystal discharge port of the fluidized bed crystallizer after reaching the requirements; Step 4: The mixture of calcium fluoride particles and water enters the drainage device. After the drainage device completes the primary dehydration and cleaning of the calcium fluoride particles, the calcium fluoride particles are piled in the buffer silo; Step 5: The calcium fluoride particles in the buffer silo are fed into a centrifugal dehydrator through a screw feeder for secondary dehydration treatment; Step 6: After the centrifugal dehydrator completes the secondary dehydration of the calcium fluoride particles, the solid content of the calcium fluoride particles is controlled to be stable above 95%. The calcium fluoride particles after the secondary dehydration are transported to the finished product packaging machine through the stacking conveying mechanism to complete the packaging.

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