Calcium fluoride reaction crystallization apparatus and control method thereof

Abstract

The application relates to the technical field of sewage treatment, and provides a calcium fluoride reaction crystallization device and a control method thereof. The device comprises a reactor, and the inner cavity of the reactor comprises a crystallization reaction zone, a mixing zone and a fluidized crystallization zone. Calcium fluoride crystals with a diameter not less than a first preset size generated in the crystallization reaction zone fall into the bottom of the reactor and are discharged through a first product outlet pipe. The first mixed solution of the crystallization reaction zone enters a separation assembly, the separation assembly enables calcium fluoride crystals with a diameter less than the first preset size and not less than a second preset size to enter the crystallization reaction zone for continuous growth. Calcium fluoride crystals with a diameter less than the second preset size enter the mixing zone. The calcium fluoride crystals with a diameter less than the second preset size are dissolved in the mixing zone to form calcium ions and fluorine ions. The liquid in the mixing zone flows into the fluidized crystallization zone for crystallization again, and the calcium fluoride crystals generated in the fluidized crystallization zone are discharged through a second product outlet pipe. The device has high crystallization rate, high fluorine recovery rate and low water turbidity.

Description

Technical Field

[0001] This application relates to wastewater treatment technology. In particular, it relates to a calcium fluoride reactive crystallization apparatus and its control method. Background Technology

[0002] Currently, calcium fluoride reactive crystallization devices typically employ fluidized beds. By adding a large amount of large-sized seed crystals as reaction carriers and controlling a high upward flow velocity of water, the particles are kept in a fluidized state to remove fluoride and recover the generated calcium fluoride crystals.

[0003] However, since fluidized beds typically involve direct discharge of wastewater after a single crystallization, there are problems such as large loss of small particles, high turbidity of effluent, and low crystallization rate. Summary of the Invention

[0004] This application provides a calcium fluoride reactive crystallization apparatus and its control method, which results in a high crystal product recovery rate and low turbidity.

[0005] In a first aspect, this application provides a calcium fluoride reactive crystallization apparatus, comprising:

[0006] The reactor, the internal cavity of which includes a crystallization reaction zone, a mixing zone and a fluidized crystallization zone;

[0007] The reactor is equipped with a first inlet pipe for discharging first wastewater into the crystallization reaction zone; the reactor is equipped with a first inlet pipe for discharging first reagent into the crystallization reaction zone; the reactor is equipped with a first seed pipe for discharging first seed crystals into the crystallization reaction zone; and the bottom of the reactor is equipped with a first product outlet pipe for discharging calcium fluoride crystals with a diameter not less than a first preset size from the crystallization reaction zone.

[0008] The separation component is configured to receive and separate the first mixture in the crystallization reaction zone, so that calcium fluoride crystals with a diameter smaller than a first preset size and not smaller than a second preset size enter the crystallization reaction zone, and calcium fluoride crystals with a diameter smaller than the second preset size enter the mixing zone.

[0009] The reactor is equipped with a second inlet pipe for discharging the second wastewater into the mixing zone; the reactor is equipped with an acid inlet pipe for discharging the acidic solution into the mixing zone, wherein the second mixed liquid in the mixing zone is acidic and the pH is less than the first preset value, so as to dissolve calcium fluoride crystals with a diameter smaller than the second preset size.

[0010] The fluidized crystallization zone is connected to the mixing zone. The reactor is equipped with a second inlet pipe for discharging the second reagent into the fluidized crystallization zone; the reactor is equipped with a second seed pipe for discharging the second seed crystal into the fluidized crystallization zone; the reactor is equipped with a second product outlet pipe for discharging calcium fluoride crystals in the fluidized crystallization zone; the reactor is equipped with a first outlet for discharging the third mixture in the fluidized crystallization zone.

[0011] In some embodiments, the reactor cavity includes a turbidity control zone, which includes an interconnected particle flocculation zone and a particle settling zone, and the particle flocculation zone is connected to a first outlet.

[0012] The reactor is equipped with a flocculant addition pipe, which is connected to the particle flocculation zone. The flocculant addition pipe is used to add flocculant to the particle flocculation zone; the effluent from the particle flocculation zone undergoes particle settling in the particle settling zone.

[0013] The reactor is equipped with a sludge outlet pipe, which is connected to the particle settling zone and is used to discharge sludge from the turbidity control zone.

[0014] A second outlet is provided at the top of the particle settling zone, which is used to discharge the supernatant from the particle settling zone.

[0015] In some embodiments, the reactor cavity includes an effluent detection zone located at the top of the turbidity control zone, and a second outlet communicates with the effluent detection zone; the reactor is provided with an effluent pipe that communicates with the effluent detection zone and with the outside of the reactor.

[0016] Also includes:

[0017] The water inlet tank is connected to both the water inlet pump and an external wastewater source. The water inlet pump is connected to both the first water inlet pipe and the second water inlet pipe.

[0018] The inlet box is connected to both the inlet pump and the external drug source. The inlet pump is connected to both the first inlet pipe and the second inlet pipe.

[0019] The reactor is equipped with a first return water pipe, which is connected to the effluent detection area, the second inlet water pipe, the first inlet water pipe, and the inlet water tank.

[0020] The reactor is equipped with a second return water pipe, which is connected to the effluent detection area, the second inlet pipe, the first inlet pipe, and the inlet tank.

[0021] In some embodiments, it also includes:

[0022] The first suspended solids detector is configured to detect the concentration of suspended solids in the liquid in the water detection zone;

[0023] The first fluoride ion detector is configured to detect the fluoride ion concentration in the liquid in the water detection zone;

[0024] The first pH detector is configured to detect the pH of the liquid in the water detection zone;

[0025] The fourth suspended solids detector is configured to detect the concentration of suspended solids in the third mixture;

[0026] The controller, the first suspended solids detector, the first fluoride ion detector, the first pH detector, and the fourth suspended solids detector are all electrically connected to the controller;

[0027] The controller is configured as follows:

[0028] If the suspended solids concentration in the liquid in the effluent detection zone is greater than the fifth preset value, and the suspended solids concentration in the third mixed liquid is greater than the sixth preset value, then the amount of second seed crystals discharged from the second seed tube to the fluidized crystallization zone needs to be increased to increase the suspended solids concentration in the fluidized bed zone; at the same time, the effluent pipe is controlled to close.

[0029] If the suspended solids concentration in the effluent detection zone is greater than the fifth preset value, while the suspended solids concentration in the third mixture is not greater than the sixth preset value, then the amount of flocculant added to the granular flocculation zone through the flocculant addition pipe will be increased; at the same time, the effluent pipe will be closed.

[0030] If the concentration of suspended solids in the liquid in the effluent detection zone is not greater than the fifth preset value, the flocculant addition tube will be kept unchanged.

[0031] In some embodiments, the controller is configured to:

[0032] When the pH of the liquid in the effluent detection zone is greater than the second preset value, and the fluoride ion concentration of the liquid in the effluent detection zone is greater than the fourth preset value, the amount of the second reagent discharged from the second inlet pipe to the fluidized crystallization zone is increased, and the amount of acidic solution discharged from the acid inlet pipe to the mixing zone is increased; at the same time, the effluent pipe is closed.

[0033] When the pH of the liquid in the effluent detection zone is greater than the second preset value, and the fluoride ion concentration of the liquid in the effluent detection zone is not greater than the fourth preset value, the amount of the second reagent discharged from the second inlet pipe to the fluidized crystallization zone is reduced, or the amount of acidic solution discharged from the acid inlet pipe to the mixing zone is increased; at the same time, the effluent pipe is closed.

[0034] When the pH of the liquid in the effluent detection zone is less than the third preset value and the fluoride ion concentration of the liquid in the effluent detection zone is greater than the fourth preset value, the amount of the second reagent discharged from the second inlet pipe into the fluidized crystallization zone is increased; at the same time, the effluent pipe is closed.

[0035] When the pH of the liquid in the effluent detection zone is less than the third preset value, and the fluoride ion concentration of the liquid in the effluent detection zone is not greater than the fourth preset value, the amount of acidic solution discharged from the acid inlet pipe to the mixing zone is reduced, or the amount of the second reagent discharged from the second inlet pipe to the fluidized crystallization zone is increased; at the same time, the effluent pipe is closed.

[0036] When the pH of the liquid in the effluent detection zone is not greater than the second preset value and not less than the third preset value, the discharge volume of the second inlet pipe and the acid inlet pipe is kept constant.

[0037] In some embodiments, including:

[0038] The second suspended solids detector is configured to detect the concentration of suspended solids in the crystallization reaction zone;

[0039] The first particle size analyzer is configured to detect the size distribution of calcium fluoride crystals in the crystallization reaction zone;

[0040] The second pH detector is configured to detect the pH of the second mixture;

[0041] The third suspended solids detector is configured to detect the concentration of suspended solids in the fluidized crystallization zone;

[0042] The second particle size analyzer is configured to detect the size distribution of calcium fluoride crystals in the fluidized crystallization zone;

[0043] The second fluoride ion detector is configured to detect the fluoride ion concentration in the liquid in the inlet tank;

[0044] The second suspended solids detector, the first particle size detector, the second pH detector, the third suspended solids detector, the second particle size detector, and the second fluoride ion detector are all electrically connected to the controller.

[0045] The controller is configured to automatically calculate the seed surface area load for fluorine in the crystallization reaction zone based on the concentration of suspended solids in the crystallization reaction zone, the size distribution of calcium fluoride crystals in the crystallization reaction zone, and the fluoride ion concentration; and to automatically calculate the seed surface area load for fluorine in the fluidized crystallization zone based on the concentration of suspended solids in the fluidized crystallization zone, the size distribution of calcium fluoride crystals in the fluidized crystallization zone, and the fluoride ion concentration.

[0046] Based on the surface area load of the fluorine seed crystals in the crystallization reaction zone, the switching frequencies of the first seed tube and the first product outlet tube are controlled. Based on the surface area load of the fluorine seed crystals in the fluidized crystallization zone, the switching frequencies of the second seed tube and the second product outlet tube are controlled.

[0047] In some embodiments, the diameter of the second seed crystal is not less than the diameter of the first seed crystal;

[0048] The fluoride concentration in the first mixture is greater than that in the second mixture;

[0049] The seed surface area loading for fluorine in the crystallization reaction zone is greater than that in the fluidized crystallization zone.

[0050] In some embodiments, the diameter of the second seed crystal is 40 to 50 micrometers; the diameter of the first seed crystal is 25 to 50 micrometers.

[0051] The fluoride concentration in the first mixture is 600 to 1000 mg / L; the fluoride concentration in the second mixture is 100 to 200 mg / L.

[0052] The seed surface area loading for fluorine in the crystallization reaction zone is 3 to 4 g / (m²). 2 •h); the seed surface area loading for fluorine in the fluidized crystallization zone is 1.5 to 3 g / (m²). 2 h).

[0053] In some embodiments, a stirring blade is also included, which is located in the crystallization reaction zone and is rotatably connected to the reactor.

[0054] The first water inlet pipe and the first chemical inlet pipe are located on opposite sides of the stirring blade, and the first water inlet pipe and the first chemical inlet pipe are at different heights. The stirring blade rotates under the action of the first wastewater sprayed from the first water inlet pipe and the first chemical agent sprayed from the first chemical inlet pipe.

[0055] In some embodiments, the stirring blades are provided with a plurality of drag-reducing holes;

[0056] And / or, the first water inlet pipe is provided with multiple spaced-apart cavities, the diameter of which decreases and then increases from the direction closer to the agitator blades to the direction farther away from the agitator blades;

[0057] And / or, the first inlet tube is provided with multiple spaced cavities, with the diameter of the cavities decreasing and increasing from the direction closest to the agitator blades to the direction furthest from the agitator blades.

[0058] In some embodiments, a first control valve is provided on the first product outlet pipe;

[0059] A weight detector is installed at the bottom of the reactor and is configured to detect the weight of calcium fluoride crystals with a diameter not less than a first preset size.

[0060] Both the weight detector and the first control valve are electrically connected to the controller. The controller is configured to open the first control valve when the weight is greater than a preset weight, so that calcium fluoride crystals not smaller than a first preset size can be discharged.

[0061] In some embodiments, the separation component includes:

[0062] The compressed air pipeline is located in the crystallization reaction zone and is connected to an external air source. The compressed air pipeline is arranged in an array along the radial and circumferential directions of the reactor.

[0063] Multiple Venturi tubes are located in the crystallization reaction zone. These Venturi tubes are arranged in a radial and circumferential array along the reactor. The Venturi tubes are perpendicular to the compressed air pipes, located at the top of the pipes, with their bottoms connected to the pipes. The sides of the Venturi tubes are connected to the crystallization reaction zone. The Venturi tubes are symmetrically arranged along the reactor's axis. Along the reactor's radial direction, from the axis furthest from the reactor to the axis closest to the reactor, the height of the Venturi tubes decreases, as does the height at which they connect to the crystallization reaction zone.

[0064] Multiple hydrocyclones are arranged in a one-to-one correspondence with multiple venturi tubes. The top of the venturi tube is connected to the hydrocyclone, the bottom of the hydrocyclone is located in the crystallization reaction zone, and the top of the hydrocyclone is located in the mixing zone.

[0065] In some embodiments, it also includes:

[0066] A liquid distribution plate is located inside the reactor to separate the mixing zone and the fluidized crystallization zone. The liquid distribution plate is provided with a connecting port that connects the mixing zone and the fluidized crystallization zone.

[0067] A fluidized bed inclined plate is located on top of a liquid distribution plate and is arranged around the periphery of the connecting port. The inner wall of the fluidized bed inclined plate is inclined, and the height of the inner wall of the fluidized bed inclined plate increases from the center of the fluidized bed inclined plate to the surrounding area.

[0068] The guide tube is located inside the fluidized bed inclined plate. There is a gap between the bottom of the guide tube and the inner wall of the fluidized bed inclined plate. The second drug inlet tube and the second seed tube are both connected to the interior of the guide tube.

[0069] Secondly, this application provides a control method for a calcium fluoride reactive crystallization apparatus, used in the aforementioned calcium fluoride reactive crystallization apparatus, the method comprising:

[0070] A first reagent, a first seed crystal, and a first wastewater are added to the crystallization reaction zone of the reactor; a second wastewater and an acidic solution are added to the mixing zone of the reactor; a second reagent and a second seed crystal are added to the fluidized crystallization zone of the reactor.

[0071] Calcium fluoride crystals with a diameter not less than the first preset size generated in the crystallization reaction zone fall to the bottom of the reactor and are discharged through the first product outlet pipe;

[0072] The first mixture in the crystallization reaction zone enters the separation component, which causes calcium fluoride crystals with a diameter smaller than the first preset size and not smaller than the second preset size to enter the crystallization reaction zone, and calcium fluoride crystals with a diameter smaller than the second preset size to enter the mixing zone.

[0073] Calcium fluoride crystals smaller than the second preset size dissolve in the mixing zone;

[0074] The liquid in the mixing zone enters the fluidized crystallization zone, and the calcium fluoride crystals generated in the fluidized crystallization zone are discharged through the first product outlet pipe. The third mixed liquid generated in the fluidized crystallization zone is discharged through the inlet and outlet.

[0075] This application provides a calcium fluoride reactive crystallization apparatus and its control method. The calcium fluoride reactive crystallization apparatus includes a reactor, the inner cavity of which includes a crystallization reaction zone, a mixing zone, and a fluidized crystallization zone. Calcium fluoride crystals with a diameter not less than a first preset size generated in the crystallization reaction zone fall to the bottom of the reactor and are discharged through a first product outlet pipe. The first mixed liquid in the crystallization reaction zone enters a separation component, which allows calcium fluoride crystals with a diameter less than the first preset size but not less than a second preset size to enter the crystallization reaction zone for further growth. Calcium fluoride crystals with a diameter less than the second preset size enter the mixing zone. Calcium fluoride crystals smaller than the second preset size dissolve in the mixing zone to form calcium ions and fluoride ions. The liquid in the mixing zone enters the fluidized crystallization zone for further crystallization, and the calcium fluoride crystals generated in the fluidized crystallization zone are discharged through a second product outlet pipe. Thus, compared to the single crystallization generating product and fine crystals in related technologies, this application generates product and fine crystals through a single crystallization, then dissolves the fine crystals and re-crystallizes them to generate the product, resulting in a higher crystal product recovery rate. Moreover, reducing fine crystals can reduce the turbidity of the effluent. Attached Figure Description

[0076] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0077] Figure 1 This is a schematic diagram of the calcium fluoride reactive crystallization apparatus provided in the embodiments of this application;

[0078] Figure 2 A schematic diagram of fluid and product flow in a calcium fluoride reactive crystallization apparatus provided in an embodiment of this application;

[0079] Figure 3 A top view of the stirring paddle, first water inlet pipe, first drug inlet pipe and first air inlet pipe in the calcium fluoride reactive crystallization apparatus provided in the embodiments of this application;

[0080] Figure 4 This is a schematic diagram of the structure of the first water inlet pipe in the calcium fluoride reactive crystallization apparatus provided in the embodiments of this application;

[0081] Figure 5 A schematic diagram of the compressed air pipeline, venturi tube, hydrocyclone and connecting pipe in the calcium fluoride reactive crystallization apparatus provided in the embodiments of this application;

[0082] Figure 6 A top view of the compressed air pipeline, cyclone separator, and connecting pipe in the calcium fluoride reactive crystallization apparatus provided in the embodiments of this application;

[0083] Figure 7 This is a schematic diagram of the structure of the Chinese Tubular tube in the calcium fluoride reactive crystallization apparatus provided in the embodiments of this application;

[0084] Figure 8 This is a schematic diagram of the hydrocyclone in the calcium fluoride reactive crystallization apparatus provided in the embodiments of this application;

[0085] Figure 9 This is a schematic flowchart illustrating the control method of the calcium fluoride reactive crystallization apparatus provided in the embodiments of this application.

[0086] Explanation of reference numerals in the attached figures:

[0087] 100 - Reactor; 110 - Crystallization reaction zone; 120 - Mixing zone; 130 - Fluidized crystallization zone; 140 - First water inlet pipe; 141 - Second control valve; 150 - First reagent inlet pipe; 151 - Third control valve; 160 - First seed crystal pipe; 161 - Sixth control valve; 170 - First product outlet pipe; 171 - First control valve; 180 - Second water inlet pipe; 181 - Seventh control valve; 190 - Acid inlet pipe; 191 - Eleventh control valve; 1100 - Second reagent inlet pipe; 1 110 - Eighth control valve; 1111 - Second seed tube; 1120 - Second product outlet pipe; 1121 - Tenth control valve; 1130 - First outlet; 1140 - Turbidity control zone; 1150 - Flocculant addition pipe; 1160 - Sludge outlet pipe; 1161 - Fifteenth control valve; 1170 - Effluent detection zone; 1180 - First return water pipe; 1181 - Fourth control valve; 1190 - Second return water pipe; 1191 - Fifth control valve; 1200 - First air inlet pipe; 12 10 - Weight detector; 1220 - Third air inlet pipe; 1230 - Water outlet pipe; 1231 - Thirteenth control valve; 200 - Separation assembly; 210 - Compressed air pipe; 220 - Venturi tube; 230 - Hydrocyclone; 240 - Connecting pipe; 250 - Second air inlet pipe; 251 - Fourteenth control valve; 300 - First suspended solids detector; 400 - First fluoride ion detector; 500 - First pH detector; 600 - Water inlet tank; 700 - Water inlet pump; 800 - Chemical inlet. Box; 900-Infeed pump; 1000-Agitator blade; 1300-Liquid distribution plate; 1310-Connecting port; 1400-Fluorescent bed inclined plate; 1500-Guide cylinder; 1600-Sludge inclined plate; 1700-Second suspended solids detector; 1800-First particle size analyzer; 1900-Second pH detector; 2000-Third suspended solids detector; 2100-Second particle size analyzer; 2200-Fourth suspended solids detector; 2300-Second fluoride ion detector. Detailed Implementation

[0088] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0089] In related technologies, calcium fluoride crystals and some fine crystals are generated during wastewater defluorination. The fine crystals cannot be used as a product, resulting in a low recovery rate of the crystal products. Moreover, the presence of fine crystals in the effluent leads to high turbidity.

[0090] To overcome the deficiencies in the prior art, the calcium fluoride reactive crystallization apparatus provided in this embodiment includes a reactor. The reactor's internal cavity includes a crystallization reaction zone, a mixing zone, and a fluidized crystallization zone. Calcium fluoride crystals with a diameter not less than a first preset size generated in the crystallization reaction zone fall to the bottom of the reactor and are discharged through a first product outlet pipe. The first mixture in the crystallization reaction zone enters a separation component, which allows calcium fluoride crystals with a diameter less than the first preset size but not less than a second preset size to enter the crystallization reaction zone for further growth. Calcium fluoride crystals with a diameter less than the second preset size enter the mixing zone. These crystals dissolve in the mixing zone to form calcium ions and fluoride ions. The liquid in the mixing zone enters the fluidized crystallization zone for further crystallization, and the calcium fluoride crystals generated in the fluidized crystallization zone are discharged through a second product outlet pipe. Thus, compared to the single crystallization process in related technologies that generates both product and fine crystals, this application generates product and fine crystals through a single crystallization process, then dissolves the fine crystals and recrystallizes them to generate the final product, resulting in a higher crystal product recovery rate. Furthermore, reducing the number of fine crystals lowers the turbidity of the effluent.

[0091] The contents of this application will now be described in detail with reference to the accompanying drawings, so that those skilled in the art can have a clearer and more detailed understanding of the contents of this application.

[0092] Figure 1 This is a schematic diagram of the calcium fluoride reactive crystallization apparatus provided in the embodiments of this application. Figure 2 This is a schematic diagram of the flow of fluids and products in the calcium fluoride reactive crystallization apparatus provided in the embodiments of this application.

[0093] See Figure 1 and Figure 2 As shown, this application provides a calcium fluoride reactive crystallization apparatus. The calcium fluoride reactive crystallization apparatus includes a reactor 100. The reactor 100 is used to provide a containment and processing space.

[0094] The reactor 100 includes a crystallization reaction zone 110, a mixing zone 120, and a fluidized crystallization zone 130.

[0095] The crystallization reaction zone 110 is located at the bottom of the reactor 100. The crystallization reaction zone 110 is used to generate calcium fluoride crystals.

[0096] The reactor 100 is provided with a first water inlet pipe 140, which is used to discharge the first wastewater to the crystallization reaction zone 110.

[0097] The reactor 100 is provided with a first inlet pipe 150, which is used to discharge the first reagent into the crystallization reaction zone 110.

[0098] The reactor 100 is equipped with a first seed tube 160, which is used to discharge the first seed crystal into the crystallization reaction zone 110.

[0099] It should be noted that the first wastewater, the first reagent, and the first seed crystal can promote the growth of calcium fluoride on the surface of the first seed crystal. By controlling the supersaturation of the liquid in the crystallization reaction zone 110 (controlling the amount of the first wastewater or the amount of fluoride ions in the first wastewater and the amount of the first reagent) and the surface area of ​​the seed crystal (controlling the number and size of the first seed crystal), the crystallization conditions can be optimized, thereby promoting the growth of calcium fluoride crystals and recovering most of the fluoride.

[0100] The bottom of the reactor 100 is provided with a first product outlet pipe 170, which is used to discharge calcium fluoride crystals with a diameter not less than a first preset size from the crystallization reaction zone 110.

[0101] It should be noted that calcium fluoride crystals with a diameter not less than the first preset size will descend to the bottom of reactor 100 under the influence of gravity. The first preset size can be 50 micrometers.

[0102] The calcium fluoride reaction crystallization apparatus includes a separation component 200. The separation component 200 is used to separate calcium fluoride crystals with a diameter smaller than a first preset size and not smaller than a second preset size, and calcium fluoride crystals with a diameter smaller than the second preset size.

[0103] The separation component 200 is partially located in the crystallization reaction zone 110, and the remaining part is located in the mixing zone 120.

[0104] The separation component 200 is configured to receive and separate the first mixture in the crystallization reaction zone 110, so that calcium fluoride crystals with a diameter smaller than the first preset size and not smaller than the second preset size enter the crystallization reaction zone 110 to continue growing, and calcium fluoride crystals with a diameter smaller than the second preset size enter the mixing zone 120.

[0105] The reactor 100 is provided with a second inlet pipe 180, which is used to discharge the second wastewater to the mixing zone 120.

[0106] The reactor 100 is provided with an acid inlet pipe 190, which is used to discharge the acidic solution to the mixing zone 120. The second mixture in the mixing zone 120 is acidic and the pH is less than the first preset value, so as to dissolve calcium fluoride crystals with a diameter smaller than the second preset size.

[0107] The first preset value can be between 1 and 3, for example, the first preset value can be 2. This is beneficial for fully dissolving the fine calcium fluoride crystals into calcium ions and fluoride ions.

[0108] The acidic solution can be either sulfuric acid or hydrochloric acid. Compared to sulfuric acid, concentrated hydrochloric acid is more volatile, placing higher requirements on the acid storage tank outside the reactor 100.

[0109] For example, the second preset size can be 10 micrometers.

[0110] The fluidized crystallization zone 130 is located at the top of the mixing zone 120 and is connected to the mixing zone 120. The second mixture in the mixing zone 120 enters the fluidized crystallization zone 130.

[0111] The reactor 100 is provided with a second inlet pipe 1100, which is used to discharge the second reagent into the fluidized crystallization zone 130.

[0112] The reactor 100 is equipped with a second seed tube 1111, which is used to discharge the second seed to the fluidized crystallization zone 130.

[0113] The reactor 100 is provided with a second product outlet pipe 1120, which is located at the lower part of the fluidized crystallization zone 130. The second product outlet pipe 1120 is used to discharge calcium fluoride crystals in the fluidized crystallization zone 130.

[0114] It should be noted that the larger diameter calcium fluoride crystals generated in the fluidized crystallization zone 130 will fall to the bottom of the fluidized crystallization zone 130 under the action of gravity, and then be discharged through the second product outlet pipe 1120.

[0115] The reactor 100 is provided with a first outlet 1130, which is located at the upper part of the fluidized crystallization zone 130. The first outlet 1130 is used to discharge the third mixture in the fluidized crystallization zone 130.

[0116] It is understood that the calcium fluoride reaction crystallization apparatus provided in this embodiment includes a reactor 100, the inner cavity of which includes a crystallization reaction zone 110, a mixing zone 120, and a fluidized crystallization zone 130. Calcium fluoride crystals with a diameter not less than a first preset size generated in the crystallization reaction zone 110 fall to the bottom of the reactor 100 and are discharged through a first product outlet pipe 170. The first mixture in the crystallization reaction zone 110 enters a separation component 200, which allows calcium fluoride crystals with a diameter less than the first preset size but not less than a second preset size to enter the crystallization reaction zone 110 for further growth. Calcium fluoride crystals with a diameter less than the second preset size enter the mixing zone 120. Calcium fluoride crystals smaller than the second preset size dissolve in the mixing zone 120 to form calcium ions and fluoride ions. The liquid in the mixing zone 120 enters the fluidized crystallization zone 130 for further crystallization, and the calcium fluoride crystals generated in the fluidized crystallization zone 130 are discharged through a second product outlet pipe 1120. Thus, compared to the single-crystallization process used in related technologies to generate both the product and fine crystals, this application generates the product and fine crystals through a single crystallization process, then dissolves the fine crystals and recrystallizes them to generate the final product. Therefore, the crystal product recovery rate is higher. Furthermore, reducing the amount of fine crystals lowers the turbidity of the effluent.

[0117] In some embodiments, the inner cavity of the reactor 100 includes a turbidity control zone 1140. The turbidity control zone 1140 is used to remove suspended solids (e.g., fine crystals) from the third mixture, thereby reducing the turbidity of the effluent.

[0118] The turbidity control zone includes an interconnected particle flocculation zone and a particle settling zone. Specifically, a partition plate can be installed in the turbidity control zone to divide it into a particle flocculation zone and a particle settling zone, and the partition plate has openings connecting the particle flocculation zone and the particle settling zone.

[0119] The particulate flocculation zone is connected to the first outlet 1130. The third mixture enters the particulate flocculation zone of the turbidity control zone 1140 through the first outlet 1130.

[0120] The reactor 100 is equipped with a flocculant addition pipe 1150, which is connected to the particle flocculation zone of the turbidity control zone 1140. The flocculant addition pipe 1150 is used to add flocculant to the particle flocculation zone of the turbidity control zone 1140. The effluent from the particle flocculation zone undergoes particle settling in the particle settling zone.

[0121] The reactor 100 is equipped with a sludge outlet pipe 1160, which is connected to the particle settling zone of the turbidity control zone 1140. The sludge outlet pipe 1160 is used to discharge sludge from the turbidity control zone 1140.

[0122] A second outlet is provided at the top of the particle settling zone of turbidity control zone 1140, which is used to discharge the supernatant of the particle settling zone.

[0123] It is understandable that adding flocculants promotes particle aggregation and sedimentation to purify the liquid and reduce the turbidity of the effluent.

[0124] In some embodiments, the inner cavity of the reactor 100 includes an effluent detection zone 1170, which is located at the top of the turbidity control zone 1140, and the second outlet is connected to the effluent detection zone 1170.

[0125] The reactor 100 is equipped with an outlet pipe 1230, which is connected to the outlet detection area 1170 and also to the outside of the reactor 100. The outlet pipe 1230 is used to discharge liquid that meets the standards from the outlet detection area 1170.

[0126] In some embodiments, the calcium fluoride reaction crystallization apparatus includes a water inlet tank 600.

[0127] The water inlet tank 600 is connected to the water inlet pump 700 and the external wastewater source, respectively. The water inlet pump 700 is connected to the first water inlet pipe 140 and the second water inlet pipe 180, respectively.

[0128] In some embodiments, the calcium fluoride reactive crystallization apparatus includes a feed tank 800.

[0129] The drug inlet box 800 is connected to the drug inlet pump and the external drug source, respectively, and the drug inlet pump 900 is connected to the first drug inlet pipe 150 and the second drug inlet pipe 1100, respectively.

[0130] In some embodiments, the reactor 100 is provided with a first return water pipe 1180. The first return water pipe 1180 is connected to the effluent detection area 1170, the second inlet water pipe 180, the first inlet water pipe 140, and the inlet water tank 600.

[0131] In this way, the effluent from the effluent detection zone 1170 can be returned to the second inlet pipe 180 to individually adjust the fluoride concentration in the fluidized crystallization zone 130 and the mixing zone 120. The effluent from the effluent detection zone 1170 can also be returned to the first inlet pipe 140 to individually adjust the fluoride concentration in the crystallization reaction zone 110. Furthermore, the effluent from the effluent detection zone 1170 that fails to meet standards can be further treated via the first return pipe 1180.

[0132] In some embodiments, the reactor 100 is provided with a second return water pipe 1190. The second return water pipe 1190 is connected to the effluent detection area 1170, the second inlet pipe 1100, the first inlet pipe 150 and the inlet tank 800, respectively.

[0133] In this way, the effluent from the effluent detection zone 1170 can be returned to the second inlet pipe 1100 to individually adjust the reagent concentration in the fluidized crystallization zone 130. The effluent from the effluent detection zone 1170 can also be returned to the first inlet pipe 150 to individually adjust the reagent concentration in the crystallization reaction zone 110. Furthermore, the effluent from the effluent detection zone 1170 can be returned to the inlet tank 800 to adjust the reagent concentration in the fluidized crystallization zone 130, the mixing zone 120, and the crystallization reaction zone 110. Moreover, the effluent from the effluent detection zone 1170 that fails to meet the standards can be further treated via the second return water pipe 1190.

[0134] The calcium fluoride reactive crystallization apparatus includes a first suspended solids detector 300. The first suspended solids detector 300 is configured to detect the concentration of suspended solids in the liquid in the effluent detection zone 1170.

[0135] For example, the turbidity of the effluent in the effluent detection zone 1170 is required to be no greater than 70 NTU (Nephelometric Turbidity Units), that is, the concentration of suspended solids in the liquid in the effluent detection zone 1170 is no greater than 70 NTU.

[0136] The calcium fluoride reaction crystallization apparatus includes a first fluoride ion detector 400, which is configured to detect the fluoride ion concentration in the liquid in the effluent detection zone 1170.

[0137] The calcium fluoride reaction crystallization apparatus includes a first pH detector 500, which is configured to detect the pH of the liquid in the effluent detection zone 1170.

[0138] The calcium fluoride reaction crystallization apparatus includes a second fluoride ion detector 2300, which is configured to detect the fluoride ion concentration of the liquid in the inlet tank 600. The second fluoride ion detector 2300 is used to stabilize the fluoride concentration in the reactor inlet by controlling the external wastewater flow rate and the return flow rate of the first return water pipe 1180.

[0139] The calcium fluoride reaction crystallization apparatus includes a controller, and a first suspended solid detector 300, a first fluoride ion detector 400, a first pH detector 500, and a second fluoride ion detector 2300 are all electrically connected to the controller.

[0140] Understandably, by using the first suspended solids detector 300, the first fluoride ion detector 400, and the first pH detector 500 to test the effluent from the calcium fluoride reaction crystallization device, the water quality can be obtained, confirming whether the water quality meets the standards. Furthermore, the reaction process parameters and additive parameters in the crystallization reaction zone 110, mixing zone 120, and fluidized crystallization zone 130 can be adjusted based on the water quality.

[0141] The controller is configured to: when the pH of the liquid in the effluent detection zone 1170 is greater than a second preset value, and the fluoride ion concentration of the liquid in the effluent detection zone 1170 is greater than a fourth preset value, then control the amount of the second reagent discharged from the second inlet pipe 1100 to the fluidized crystallization zone 130 to increase, and control the amount of acidic solution discharged from the acid inlet pipe 190 to the mixing zone 120 to increase. Simultaneously, control the effluent pipe 1230 to close.

[0142] The controller is configured to: when the pH of the liquid in the effluent detection zone 1170 is greater than a second preset value, and the fluoride ion concentration of the liquid in the effluent detection zone 1170 is not greater than a fourth preset value, then control the amount of the second reagent discharged from the second inlet pipe 1100 to the fluidized crystallization zone 130 to decrease, and control the amount of acidic solution discharged from the acid inlet pipe 190 to the mixing zone 120 to increase. Simultaneously, control the effluent pipe 1230 to close.

[0143] It should be noted that the opening degree can be adjusted by controlling the valve. Furthermore, reducing the chemical flow rate should be prioritized to conserve chemical.

[0144] The second preset value can be 9.

[0145] When the pH of the liquid in the effluent detection zone 1170 is less than the third preset value, and the fluoride ion concentration of the liquid in the effluent detection zone 1170 is greater than the fourth preset value, the amount of the second reagent discharged from the second inlet pipe 1100 to the fluidized crystallization zone 130 is increased. At the same time, the effluent pipe 1230 is closed.

[0146] The third preset value can be 6, and the fourth preset value can be 8 mg / L.

[0147] It should be noted that the opening degree of the control valve can be adjusted.

[0148] When the pH of the liquid in the effluent detection zone 1170 is less than the third preset value, and the fluoride ion concentration of the liquid in the effluent detection zone 1170 is not greater than the fourth preset value, the amount of acidic solution discharged from the acid inlet pipe 190 to the mixing zone 120 is reduced, or the amount of the second reagent discharged from the second reagent inlet pipe 1100 to the fluidized crystallization zone 130 is increased. Simultaneously, the effluent pipe 1230 is closed.

[0149] The third preset value can be 6, and the fourth preset value can be 8 mg / L.

[0150] It should be noted that this can be adjusted by controlling the valve opening. Prioritize reducing the flow rate of the acidic solution to conserve reagents.

[0151] When the pH of the liquid in the effluent detection zone 1170 is not greater than the second preset value and not less than the third preset value, the discharge rate of the second inlet pipe 1100 and the acid inlet pipe 190 is kept constant.

[0152] It should be noted that the pH of the effluent from the effluent testing area 1170 must be no greater than 9 and no less than 6.

[0153] If the suspended solids concentration in the liquid in the effluent detection zone 1170 exceeds the fifth preset value, and the suspended solids concentration in the third mixed liquid exceeds the sixth preset value, then the amount of second seed crystals discharged from the second seed tube 1111 into the fluidized crystallization zone 130 is increased. Simultaneously, the effluent pipe 1230 is closed.

[0154] The fifth preset value can be 70 NTU, and the sixth preset value can be 200 NTU.

[0155] It should be noted that the opening degree of the control valve can be adjusted.

[0156] If the suspended solids concentration in the liquid in the effluent detection zone 1170 is greater than the fifth preset value, while the suspended solids concentration in the third mixture is not greater than the sixth preset value, then the amount of flocculant added to the granular flocculation zone via the flocculant addition pipe 1150 will be increased. Simultaneously, the effluent pipe 1230 will be closed.

[0157] It should be noted that the opening degree of the control valve can be adjusted.

[0158] It should be noted that the turbidity of the effluent from the effluent testing area 1170 should not exceed 70 NTU.

[0159] Understandably, if the effluent does not meet the standards, the effluent will be returned to the inlet tank 600 and the chemical inlet tank 800, and will re-enter the device for reaction instead of being directly discharged.

[0160] In some embodiments, a second suspended solids detector 1700 is also included, which is configured to detect the concentration of suspended solids in the crystallization reaction zone 110.

[0161] In some embodiments, a first particle size analyzer 1800 is also included, which is configured to detect the size distribution of calcium fluoride crystals in the crystallization reaction zone 110.

[0162] It should be noted that the crystallization reaction zone 110 is monitored by using the second suspended solids detector 1700 and the first particle size analyzer 1800.

[0163] In some embodiments, a second pH detector 1900 is also included, which is configured to detect the pH of the second mixture.

[0164] In this way, the pH of the second mixture can be monitored by setting up a second pH detector 1900. This ensures the dissolution of fine crystals, and if the pH exceeds the limit, the amount of sulfuric acid added is controlled to increase.

[0165] In some embodiments, a third suspended solids detector 2000 is also included, which is configured to detect the concentration of suspended solids in the fluidized crystallization zone 130.

[0166] In some embodiments, a second particle size analyzer 2100 is also included, which is configured to detect the size distribution of calcium fluoride crystals in the fluidized crystallization zone 130.

[0167] The second suspended solids detector 1700, the first particle size analyzer 1800, the second pH detector 1900, the third suspended solids detector 2000, and the second particle size analyzer 2100 are all electrically connected to the controller.

[0168] It should be noted that the reaction status of the fluidized crystallization zone 130 can be monitored by using the third suspended solids detector 2000 and the second particle size analyzer 2100 to detect the fluidized crystallization zone 130.

[0169] The controller is configured to automatically calculate the seed surface area loading for fluorine in the crystallization reaction zone 110 based on the suspended solids concentration, the size distribution of calcium fluoride crystals in the crystallization reaction zone 110, and the fluoride ion concentration of the liquid. Similarly, it is configured to automatically calculate the seed surface area loading for fluorine in the fluidized crystallization zone 130 based on the suspended solids concentration, the size distribution of calcium fluoride crystals in the fluidized crystallization zone 130, and the fluoride ion concentration of the liquid.

[0170] Specifically, the calculation formula is as follows:

[0171]

[0172] Where 2.8 is the specific gravity of calcium fluoride particles, in g / mL.

[0173] F represents the influent fluoride concentration, expressed in mg / L.

[0174] Q represents the influent flow rate, measured in L / h.

[0175] D 50 The particle size is measured in micrometers (µm). It was determined using a particle size analyzer.

[0176] n is the empirical coefficient in actual operation.

[0177] SS represents the suspended solids concentration, measured in mg / L. It is detected using a suspended solids detector.

[0178] V represents the volume of the reaction zone, measured in liters (L).

[0179] .

[0180] Based on the surface area load of fluorine-containing seed crystals in the crystallization reaction zone 110, the switching frequencies of the first seed tube 160 and the first product outlet tube 170 are controlled. Based on the surface area load of fluorine-containing seed crystals in the fluidized crystallization zone 130, the switching frequencies of the second seed tube 1111 and the second product outlet tube 1120 are controlled.

[0181] Specifically, if the seed crystal surface area loading for fluorine is higher than the specified range, the seed crystal surface area loading is reduced to the specified range by increasing the frequency of seed crystal addition. If the seed crystal surface area loading for fluorine is lower than the specified range, the seed crystal surface area loading is increased to the specified range by increasing the frequency of product emission.

[0182] In some embodiments, a second control valve 141 is provided on the first inlet pipe 140. A third control valve 151 is provided on the first inlet pipe 150. A plurality of fourth control valves 1181 are provided on the first return pipe 1180, corresponding to the outlet detection area 1170, the second inlet pipe 180, the first inlet pipe 140, and the inlet tank 600, respectively. A plurality of fifth control valves 1191 are provided on the second return pipe 1190, corresponding to the outlet detection area 1170, the second inlet pipe 1100, the first inlet pipe 150, and the inlet tank 800, respectively. A sixth control valve 161 is provided on the first seed tube 160. A seventh control valve 181 is provided on the second inlet pipe 180. An eighth control valve 1110 is provided on the second inlet pipe 1100. A ninth control valve is provided on the second seed tube 1111. A tenth control valve 1121 is provided on the second product outlet pipe 1120. An eleventh control valve 191 is installed on the acid inlet pipe 190.

[0183] Among them, the second control valve 141, the third control valve 151, the fourth control valve 1181, the fifth control valve 1191, the sixth control valve 161, the seventh control valve 181, the eighth control valve 1110, the ninth control valve, the tenth control valve 1121 and the eleventh control valve 191 are all electrically connected to the controller.

[0184] It should be noted that the number of fourth control valves 1181 can be four, or the number of fourth control valves 1181 can be three. Since a portion of the piping between the first return water pipe 1180 and the second inlet water pipe 180 is shared, one fourth control valve 1181 can be eliminated. Similarly, the number of fifth control valves 1191 can be four, or the number of fifth control valves 1191 can be three. Since a portion of the piping between the second return water pipe 1190 and the second inlet drug pipe 1100 is shared, one fifth control valve 1191 can be eliminated.

[0185] Understandably, the surface area of ​​the first seed crystal is controlled by adjusting the opening frequency of the sixth control valve 161 on the first seed crystal tube 160 and the first control valve 171 on the first product outlet pipe 170. The supersaturation in the crystallization reaction zone 110 is controlled by adjusting the opening degree of the second control valve 141 on the first water inlet pipe 140, the opening degree of the third control valve 151 on the first chemical inlet pipe 150, and the ratio of the fifth control valve 1191 on the second return water pipe 1190. The concentration of fluoride in the incoming water in the mixing zone 120 is controlled by adjusting the opening degree of the third control valve 151 on the second water inlet pipe 180 and the ratio of the fourth control valve 1181 on the first return water pipe 1180. The pH in the mixing zone 120 is controlled by adjusting the opening degree of the third control valve 151 on the second water inlet pipe 180 and the eleventh control valve 191 on the acid inlet pipe 190. The supersaturation in the fluidized crystallization zone 130 is controlled by adjusting the opening degree of the eighth control valve 1110 on the second inlet pipe 1100 and the reflux flow rate ratio of the fifth control valve 1191 on the second return water pipe 1190. The surface area of ​​the second seed crystal is controlled by adjusting the opening frequency of the ninth control valve on the second seed tube 1111 and the opening frequency of the tenth control valve 1121 on the second product outlet pipe 1120. This reduces the difficulty and cost of manual operation.

[0186] In some embodiments, a fourth suspended solids detector 2200 is also included. The third suspended solids detector 2000 is disposed outside the guide tube 1500. The fourth suspended solids detector 2200 is used to detect the concentration of suspended solids in the third mixture. A twelfth control valve is provided on the flocculant addition pipe 1150. Both the fourth suspended solids detector 2200 and the twelfth control valve are electrically connected to the controller. The opening degree of the twelfth control valve is controlled by the concentration of suspended solids in the third mixture detected by the fourth suspended solids detector 2200, thereby controlling the amount of flocculant added and saving flocculant usage.

[0187] In some embodiments, the sludge outlet pipe 1160 is provided with a fifteenth control valve 1161, which is electrically connected to the controller.

[0188] In some embodiments, the water outlet pipe 1230 is provided with a thirteenth control valve 1231, which is electrically connected to the controller.

[0189] In some embodiments, the diameter of the second seed crystal is not less than the diameter of the first seed crystal.

[0190] Thus, since the cross-sectional area and volume of the fluidized crystallization zone 130 are smaller than those of the crystallization reaction zone 110, the residence time is shorter, the upward flow rate is faster, and the concentration of fluorine in the reaction is lower, resulting in a slower crystal growth rate, in order to effectively avoid seed loss and maintain a good fluidization state, it is necessary to ensure that the size of the second seed is larger.

[0191] In some embodiments, the fluoride concentration in the first mixture is greater than the fluoride concentration in the second mixture.

[0192] Thus, the crystallization reaction zone 110 is the main defluorination crystallization reaction zone. The high fluoride concentration leads to rapid crystal growth, which can improve the product formation rate. The mixing zone 120 and the fluidized crystallization zone 130 are secondary crystallization reaction zones, mainly to reduce the fine crystals produced in the crystallization reaction zone 110. If the fluoride concentration is high, it can easily lead to high turbidity in the effluent from the fluidized crystallization zone 130, making it difficult to stabilize the turbidity at a low level.

[0193] In some embodiments, the seed surface area load for fluorine in the crystallization reaction zone 110 is greater than that for fluorine in the fluidized crystallization zone 130.

[0194] Thus, a high surface area loading of fluorine crystals can increase the crystal growth rate, but it easily leads to local supersaturation and the formation of fine crystals. A low surface area loading of fluorine crystals results in a lower crystal growth rate, but it can reduce the amount of fine crystals formed. Crystallization reaction zone 110 is the primary defluorination crystallization reaction zone; the high fluorine concentration leads to rapid crystal growth, which can increase the product formation rate. Fluidized crystallization zone 130 is a secondary crystallization reaction zone, primarily designed to reduce the amount of fine crystals formed in crystallization reaction zone 110; therefore, it is necessary to reduce the amount of fine crystals formed.

[0195] In some embodiments, the first preset size can be 50 micrometers. The size of the calcium fluoride crystals discharged from the first product outlet pipe 170 is 50 to 100 micrometers. The size of the calcium fluoride crystals discharged from the second product outlet pipe 1120 is 40 to 60 micrometers.

[0196] It should be noted that in the wet process of hydrofluoric acid industrial production, hydrofluoric acid is mainly generated by the reaction of calcium fluoride and sulfuric acid. In order to ensure reaction efficiency and production stability, the particle size of calcium fluoride is required to be 50 to 100 micrometers. In this embodiment, the calcium fluoride crystals produced by the calcium fluoride reaction crystallization device are small in size, so there is no need to add grinding treatment, which reduces the production cost.

[0197] In some embodiments, the diameter of the second seed crystal is 40 to 50 micrometers.

[0198] When the diameter of the second seed crystal is less than 40 micrometers, the seed crystal in the fluidized crystallization zone 130 is easily lost.

[0199] When the diameter of the second seed crystal is greater than 50 micrometers, the specific surface area of ​​the seed crystal decreases, requiring a higher seed crystal addition rate, and the amount of fine crystals generated increases.

[0200] In some embodiments, the diameter of the first seed crystal is 25 to 50 micrometers.

[0201] When the diameter of the first seed crystal is less than 25 micrometers, the product generation rate in the crystallization reaction zone 110 slows down.

[0202] When the diameter of the first seed crystal is greater than 50 micrometers, the specific surface area of ​​the seed crystal decreases, requiring a higher seed crystal addition rate, and the amount of fine crystals generated increases.

[0203] In some embodiments, the fluoride concentration in the first mixture is 600 to 1000 mg / L.

[0204] When the fluoride concentration in the first mixture is less than 600 mg / L, the crystal growth rate slows down, the product formation rate is slow, and the product discharge time is prolonged.

[0205] When the fluoride concentration in the first mixture is greater than 1000 mg / L, it is necessary to increase the effluent return flow rate or decrease the external wastewater flow rate; otherwise, it may lead to an increase in the amount of fine crystals formed and a decrease in the fluoride recovery rate.

[0206] In some embodiments, the fluoride concentration in the second mixture is 100 to 200 mg / L.

[0207] When the fluoride concentration in the second mixture is less than 100 mg / L, the crystal growth rate slows down, the product formation rate is slow, and the product discharge time is prolonged.

[0208] When the fluoride concentration in the second mixture is greater than 200 mg / L, it is necessary to increase the effluent return flow rate or decrease the external wastewater flow rate; otherwise, it may lead to an increase in the amount of fine crystals formed and a decrease in the fluoride recovery rate.

[0209] In some embodiments, the seed surface area loading for fluorine in the crystallization reaction zone 110 is 3 to 4 g / (m²). 2 ·h).

[0210] When the surface area loading of fluorine seeds in crystallization reaction zone 110 is less than 3 g / (m²), 2 When ·h), it will result in a low crystal growth rate, but it can reduce the amount of fine crystals formed.

[0211] When the surface area loading of fluorine-containing seed crystals in crystallization reaction zone 110 is greater than 4 g / (m²), 2 When ·h), the crystal growth rate can be increased, but local supersaturation is easily generated, resulting in fine crystals.

[0212] In some embodiments, the seed surface area loading for fluorine in the fluidized crystallization zone 130 is 1.5 to 3 g / (m²). 2 ·h).

[0213] When the surface area loading of the seed crystals in the fluidized crystallization zone 130 is less than 1.5 g / (m²) 2 When ·h), it will result in a low crystal growth rate, but it can reduce the amount of fine crystals formed.

[0214] When the surface area loading of the seed crystals in the fluidized crystallization zone 130 is greater than 3 g / (m²) 2 When ·h), the crystal growth rate can be increased, but local supersaturation is easily generated, resulting in fine crystals.

[0215] Figure 3 This is a top view of the stirring paddle, first water inlet pipe, first drug inlet pipe, and first air inlet pipe in the calcium fluoride reactive crystallization apparatus provided in the embodiments of this application.

[0216] See Figures 1 to 3 As shown, in some embodiments, the calcium fluoride reaction crystallization apparatus includes a stirring blade 1000, which is located in the crystallization reaction zone 110 and is rotatably connected to the reactor 100.

[0217] The first water inlet pipe 140 and the first medicine inlet pipe 150 are located on opposite sides of the stirring blade 1000, and the first water inlet pipe 140 and the first medicine inlet pipe 150 are at different heights. The stirring blade 1000 rotates under the action of the first wastewater sprayed from the first water inlet pipe 140 and the first medicine sprayed from the first medicine inlet pipe 150.

[0218] Specifically, the stirring blade 1000 can be a frame-type stirring blade.

[0219] Understandably, using the stirring blade 1000 for stirring can improve the uniformity of the substances in the crystallization reaction zone 110, which is beneficial for accelerating the reaction. Furthermore, the use of the first wastewater sprayed from the first water inlet pipe 140 and the first reagent sprayed from the first reagent inlet pipe 150 for driving eliminates the need for a power unit, thus reducing energy consumption. The rotational speed of the stirring blade 1000 can be controlled by the flow rates of the water and reagent inlet.

[0220] In some embodiments, the first water inlet pipe 140 and the first medicine inlet pipe 150 are diagonally distributed.

[0221] In some embodiments, the flow impact regions corresponding to the first water inlet pipe 140 and the first medicine inlet pipe 150 are both 1 / 4 of the circumference of the stirring blade 1000.

[0222] In some embodiments, the reactor 100 is provided with a first air inlet pipe 1200, which is connected to the crystallization reaction zone 110 and an external air source. Specifically, the first air inlet pipe 1200 is located on one side of the stirring blade 1000. In this way, the amount of air entering through the first air inlet pipe 1200 can help adjust the rotational speed of the stirring blade 1000.

[0223] In some embodiments, the stirring blade 1000 is provided with a plurality of drag-reducing holes. The drag-reducing holes can reduce stirring resistance.

[0224] Among them, multiple drag-reducing holes can be evenly distributed.

[0225] Figure 4 This is a schematic diagram of the structure of the first water inlet pipe in the calcium fluoride reactive crystallization apparatus provided in the embodiments of this application.

[0226] See Figure 1 , Figure 2 and Figure 4 As shown, in some embodiments, the first inlet pipe 140 is provided with multiple spaced-apart cavities, the diameter of which decreases and then increases from the direction near the stirring blade 1000 to the direction away from the stirring blade 1000. This allows the first wastewater to enter the crystallization reaction zone 110 at a faster speed and with a larger spray range.

[0227] In some embodiments, the first inlet pipe 150 is provided with a plurality of spaced-apart cavities, the diameter of which decreases and then increases from the direction near the stirring blade 1000 to the direction away from the stirring blade 1000. This allows the first agent to enter the crystallization reaction zone 110 at a faster speed and with a larger spray range.

[0228] In some embodiments, the second inlet pipe 180 is provided with a plurality of spaced-apart cavities, the diameter of which decreases and then increases from the axis near the reactor 100 to the axis away from the reactor 100. This allows the second wastewater to enter the mixing zone 120 at a faster speed and with a larger spray range.

[0229] In some embodiments, the second drug inlet tube 1100 is provided with a plurality of spaced-apart lumens.

[0230] See Figure 1 and Figure 2 As shown, in some embodiments, a first control valve 171 is provided on the first product outlet pipe 170.

[0231] The calcium fluoride reaction crystallization apparatus includes a weight detector 1210. The weight detector 1210 is located at the bottom of the reactor 100 and is configured to detect the weight of calcium fluoride crystals with a diameter not less than a first preset size.

[0232] Both the weight detector 1210 and the first control valve 171 are electrically connected to the controller, which is configured to open the first control valve when the weight is greater than a preset weight, so that calcium fluoride crystals not smaller than a first preset size can be discharged.

[0233] Specifically, the weight detector 1210 gravity sensor.

[0234] Specifically, the bottom of reactor 100 is conical.

[0235] Figure 5 This is a schematic diagram of the compressed air pipeline, venturi tube, hydrocyclone, and connecting pipe in the calcium fluoride reactive crystallization apparatus provided in the embodiments of this application. Figure 6 This is a top view of the compressed air pipe, cyclone separator, and connecting pipe in the calcium fluoride reactive crystallization apparatus provided in the embodiments of this application. Figure 7 This is a schematic diagram of the structure of the Chinese-language tube in the calcium fluoride reactive crystallization apparatus provided in the embodiments of this application. Figure 8 This is a schematic diagram of the hydrocyclone in the calcium fluoride reactive crystallization apparatus provided in the embodiments of this application.

[0236] See Figure 1 , Figure 2 , Figures 5 to 8 As shown, in some embodiments, the separation component 200 includes a compressed air conduit 210.

[0237] The compressed air pipeline 210 is located in the crystallization reaction zone 110 and is connected to an external air source. The compressed air pipeline 210 is arranged in a radial and circumferential array along the reactor 100. That is, the compressed air pipeline 210 is arranged in multiple concentric circles.

[0238] In some embodiments, the separation assembly 200 includes a plurality of Venturi tubes 220. The plurality of Venturi tubes 220 are located in the crystallization reaction zone 110 and are arranged in a radial and circumferential array along the reactor 100. The Venturi tubes 220 are arranged perpendicularly to the compressed air pipe 210, with the top of the Venturi tubes 220 and the bottom of the Venturi tubes 220 communicating with the compressed air pipe 210. The sides of the Venturi tubes 220 are also connected to the crystallization reaction zone 110.

[0239] In some embodiments, the separation assembly 200 includes a plurality of hydrocyclones 230. The plurality of hydrocyclones 230 are arranged one-to-one with a plurality of venturi tubes 220, the top of the venturi tubes 220 is in communication with the hydrocyclones 230, the bottom of the hydrocyclones 230 is located in the crystallization reaction zone 110, and the top of the hydrocyclones 230 is located in the mixing zone 120.

[0240] Compressed air supplied by an external air source enters the compressed air pipe 210 and flows upward along the venturi tube 220, creating a local pressure drop. Under the action of the pressure difference, the first mixture in the crystallization reaction zone 110 is drawn into the venturi tube 220 and then enters the hydrocyclone 230. In the hydrocyclone 230, the first mixture is separated by centrifugal and centripetal forces. Calcium fluoride crystals with a diameter smaller than the first preset size and not smaller than the second preset size enter the crystallization reaction zone 110 from the bottom of the hydrocyclone 230 to continue growing. Calcium fluoride crystals with a diameter smaller than the second preset size enter the mixing zone 120 from the top of the hydrocyclone 230.

[0241] Understandably, by arranging compressed air pipes 210 in a radial and circumferential array along the reactor 100, with Venturi tubes 220 perpendicularly positioned to the compressed air pipes 210, and multiple Venturi tubes 220 arranged radially and circumferentially along the reactor 100, and multiple hydrocyclones 230 corresponding one-to-one with the multiple Venturi tubes 220, the relatively large size of the compressed air pipes 210 and the large number of Venturi tubes 220 and hydrocyclones 230 can enhance the turbulence in the crystallization reaction zone 110, improving its uniformity. Simultaneously, it enhances the material flow between the crystallization reaction zone 110 and the mixing zone 120.

[0242] It should be noted that the hydrocyclone 230 can be a hydrocyclone commonly used in related technologies, and its structure will not be described in detail in this embodiment.

[0243] In some embodiments, the separation assembly 200 includes a connecting pipe 240 communicating with the bottom of a hydrocyclone 230. One connecting pipe 240 corresponds to a plurality of hydrocyclones 230 along the radius of the reactor 100. In this way, calcium fluoride crystals smaller than a first preset value and not smaller than a second preset size separated by the plurality of hydrocyclones 230 along the radius of the reactor 100 can be introduced into the middle region of the crystallization reaction zone 110.

[0244] See Figure 6 As shown, there are 8 connecting pipes 240, and each connecting pipe 240 is connected to four hydrocyclones 230.

[0245] In some embodiments, a plurality of Venturi tubes 220 are symmetrically arranged along the axis of the reactor 100. Along the radial direction of the reactor 100, and from the axis away from the reactor 100 to the axis closer to the reactor 100, the height of the Venturi tubes 220 decreases, and the height at which the Venturi tubes 220 communicate with the crystallization reaction zone 110 decreases. In this way, the Venturi tubes 220 can draw in the first mixture at different heights, which can enhance the turbulence in the crystallization reaction zone 110, effectively prevent the formation of eddies, and improve the homogeneity of the material within the crystallization reaction zone 110. Simultaneously, it enhances the material flow between the crystallization reaction zone 110 and the mixing zone 120.

[0246] In some embodiments, the bottom of the mixing zone 120 is conical. Along the radial direction of the reactor 100, and from the axis away from the reactor 100 to the axis closer to the reactor 100, the height of the bottom of the mixing zone 120 decreases. The second air inlet pipe 250 is connected to the center of the compressed air pipe 210 and to the mixing zone 120. In this way, calcium fluoride crystals precipitated at the bottom of the mixing zone 120 can slide along the bottom of the mixing zone 120 to the middle position, and then move upwards under the action of the compressed air supplied by the second air inlet pipe 250, thereby allowing the calcium fluoride crystals to dissolve sufficiently. Furthermore, the provision of the second air inlet pipe 250 facilitates uniform mixing of the second mixture.

[0247] In some embodiments, a fourteenth control valve 251 is provided on the second air intake pipe 250, and the fourteenth control valve 251 is electrically connected to the controller.

[0248] See Figure 1 and Figure 2 As shown, in some embodiments, the calcium fluoride reactive crystallization apparatus includes a liquid distribution plate 1300.

[0249] The liquid distribution plate 1300 is located inside the reactor 100 to separate the mixing zone 120 and the fluidized crystallization zone 130. The liquid distribution plate 1300 is provided with a connecting port 1310, which connects the mixing zone 120 and the fluidized crystallization zone 130.

[0250] In some embodiments, the calcium fluoride reactive crystallization apparatus includes a fluidized bed slab 1400. The fluidized bed slab 1400 is located on top of the liquid distribution plate 1300 and is arranged around the periphery of the communication port 1310. The inner wall of the fluidized bed slab 1400 is inclined, and the height of the inner wall of the fluidized bed slab 1400 increases from the center of the fluidized bed slab 1400 to the surrounding area.

[0251] In some embodiments, the calcium fluoride reactive crystallization apparatus includes a flow guide tube 1500, which is located inside a fluidized bed inclined plate 1400. The bottom of the flow guide tube 1500 has a gap with the inner wall of the fluidized bed inclined plate 1400. The second drug inlet tube 1100 and the second seed tube 1111 are both in communication with the interior of the flow guide tube 1500.

[0252] Understandably, by setting the liquid distribution plate 1300 and the connecting port 1310, the area of ​​the fluidized crystallization zone 130 can be controlled to ensure sufficient upward flow velocity and promote seed crystal fluidization. Furthermore, by setting the fluidized bed inclined plate 1400 and the guide tube 1500, the inner wall of the fluidized bed inclined plate 1400 is inclined, and the height of the inner wall of the fluidized bed inclined plate 1400 increases from the center outwards. The guide tube 1500 is located inside the fluidized bed inclined plate 1400, and there is a gap between the bottom of the guide tube 1500 and the inner wall of the fluidized bed inclined plate 1400. In this way, the calcium fluoride crystals precipitated on the fluidized bed inclined plate 1400 can slide downwards along the fluidized bed inclined plate 1400 into the guide tube 1500, and thus can be smoothly discharged from the second product outlet pipe 1120.

[0253] In some embodiments, the communication port 1310 includes a plurality of spaced-apart communication holes, thereby effectively preventing the second seed crystal and calcium fluoride crystal from falling out of the communication port 1310 into the mixing region 120.

[0254] In some embodiments, the turbidity control zone 1140 is located on one side of the fluidized crystallization zone 130.

[0255] In some embodiments, the turbidity control zone 1140 is provided with a sludge inclined plate 1600, the inner wall of which is inclined and the height of the inner wall increases from the center to the periphery. A sludge outlet pipe 1160 is located at the bottom center of the sludge inclined plate 1600. This allows the sludge generated in the turbidity control zone 1140 to slide along the inner wall of the sludge inclined plate 1600 to the sludge outlet pipe 1160 and then be discharged through the sludge outlet pipe 1160.

[0256] In some embodiments, a third air inlet pipe 1220 is also included, which is connected to the particulate flocculation zone of the turbidity control zone 1140 and an external air source, respectively. This can improve the uniformity of the distribution of substances in the particulate flocculation zone.

[0257] In some embodiments, the effluent monitoring area is a hemispherical region with an overflow weir. This allows some impurities to settle, reducing the turbidity of the effluent.

[0258] Figure 9 This is a schematic flowchart illustrating the control method of the calcium fluoride reactive crystallization apparatus provided in the embodiments of this application.

[0259] See Figure 9 As shown, this application provides a control method for a calcium fluoride reactive crystallization apparatus, used in the aforementioned calcium fluoride reactive crystallization apparatus, the method comprising:

[0260] S101. Add a first reagent, a first seed crystal, and a first wastewater to the crystallization reaction zone of the reactor; add a second wastewater and an acidic solution to the mixing zone of the reactor; add a second reagent and a second seed crystal to the fluidized crystallization zone of the reactor.

[0261] S102. Calcium fluoride crystals with a diameter not less than the first preset size generated in the crystallization reaction zone fall to the bottom of the reactor and are discharged through the first product outlet pipe.

[0262] S103. The first mixture in the crystallization reaction zone enters the separation component. The separation component causes calcium fluoride crystals with a diameter smaller than the first preset size and not smaller than the second preset size to enter the crystallization reaction zone, and calcium fluoride crystals with a diameter smaller than the second preset size to enter the mixing zone.

[0263] S104. Calcium fluoride crystals smaller than the second preset size dissolve in the mixing zone.

[0264] S105. The liquid in the mixing zone enters the fluidized crystallization zone. The calcium fluoride crystals generated in the fluidized crystallization zone are discharged through the second product outlet pipe, and the third mixed liquid generated in the fluidized crystallization zone is discharged through the inlet and outlet.

[0265] Understandably, calcium fluoride crystals with a diameter not less than the first preset size generated in the crystallization reaction zone 110 fall to the bottom of the reactor 100 and are discharged through the first product outlet pipe 170. The first mixture in the crystallization reaction zone 110 enters the separation component 200, which allows calcium fluoride crystals with a diameter less than the first preset size but not less than the second preset size to continue growing in the crystallization reaction zone 110. Calcium fluoride crystals with a diameter less than the second preset size enter the mixing zone 120. Calcium fluoride crystals smaller than the second preset size dissolve in the mixing zone 120 to form calcium ions and fluoride ions. The liquid in the mixing zone 120 enters the fluidized crystallization zone 130 for re-crystallization, and the calcium fluoride crystals generated in the fluidized crystallization zone 130 are discharged through the second product outlet pipe 1120. Thus, compared to the single crystallization process in related technologies that generates both product and fine crystals, this application generates product and fine crystals through a single crystallization process, then dissolves the fine crystals and re-crystallizes them to generate the product, resulting in a higher crystal product recovery rate. Moreover, reducing the number of fine crystals can lower the turbidity of the effluent.

[0266] It should be noted that the terms "one embodiment," "embodiment," "exemplary embodiment," "some embodiments," etc., mentioned in the specification indicate that the described embodiment may include a specific feature, structure, or characteristic, but not every embodiment necessarily includes that specific feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Moreover, when a specific feature, structure, or characteristic is described in connection with an embodiment, implementing such a feature, structure, or characteristic in conjunction with other embodiments, whether explicitly described or not, is within the knowledge scope of those skilled in the art.

[0267] Generally speaking, terms should be understood at least in part by their use in context. For example, at least in part by context, the term "one or more" as used in the text can be used to describe any feature, structure, or characteristic of the singular meaning, or a combination of features, structures, or characteristics of the plural meaning. Similarly, at least in part by context, terms such as "a" or "the" can also be understood to convey either singular or plural usage.

[0268] It should be readily understood that the terms “on,” “above,” and “on top of” in this application should be interpreted in the broadest possible sense, such that “on” means not only “directly on something” but also “on something” with an intermediate feature or layer therebetween, and that “above” or “on top of” means not only “on something” but also “on something” without an intermediate feature or layer therebetween (i.e., directly on something).

[0269] Furthermore, for ease of explanation, spatially relative terms such as "below," "below," "under," "above," and "above" may be used to describe the relationship of one element or feature relative to other elements or features as shown in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation other than those shown in the figures. The device may have other orientations (rotated 90° or in other orientations), and the spatially relative descriptive terms used herein may be interpreted accordingly.

[0270] It should be noted that the brief descriptions of terms in this application are only for the convenience of understanding the embodiments described below, and are not intended to limit the embodiments of this application. Unless otherwise stated, these terms should be understood in their ordinary and common meaning.

[0271] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover but not exclusively include, for example, a product or device that includes a series of components is not necessarily limited to those that are explicitly listed, but may include other components that are not explicitly listed or that are inherent to such product or device.

[0272] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0273] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0274] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0275] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A calcium fluoride reactive crystallization apparatus, characterized in that, include: The reactor, wherein the internal cavity of the reactor includes a crystallization reaction zone, a mixing zone, and a fluidized crystallization zone; The reactor is provided with a first inlet pipe for discharging first wastewater into the crystallization reaction zone; the reactor is provided with a first inlet pipe for discharging first reagent into the crystallization reaction zone; the reactor is provided with a first seed crystal pipe for discharging first seed crystal into the crystallization reaction zone; and the bottom of the reactor is provided with a first product outlet pipe for discharging calcium fluoride crystals with a diameter not less than a first preset size in the crystallization reaction zone. A separation component is configured to receive and separate a first mixture in the crystallization reaction zone, so that calcium fluoride crystals with a diameter smaller than the first preset size and not smaller than the second preset size enter the crystallization reaction zone, and calcium fluoride crystals with a diameter smaller than the second preset size enter the mixing zone. The reactor is equipped with a second inlet pipe for discharging second wastewater into the mixing zone; the reactor is equipped with an acid inlet pipe for discharging acidic solution into the mixing zone, wherein the second mixture in the mixing zone is acidic and the pH is less than a first preset value, so as to dissolve calcium fluoride crystals with a diameter smaller than the second preset size; The fluidized crystallization zone is connected to the mixing zone. The reactor is provided with a second inlet pipe for discharging the second reagent into the fluidized crystallization zone; the reactor is provided with a second seed pipe for discharging the second seed crystal into the fluidized crystallization zone; and the reactor is provided with a second product outlet pipe for discharging calcium fluoride crystals from the fluidized crystallization zone. The reactor is provided with a first outlet, which is used to discharge the third mixture in the fluidized crystallization zone; The separation component includes: A compressed air pipeline is located in the crystallization reaction zone. The compressed air pipeline is connected to an external air source and is arranged in a radial and circumferential array along the reactor. Multiple Venturi tubes are located in the crystallization reaction zone. These Venturi tubes are arranged in a radial and circumferential array along the reactor. The Venturi tubes are perpendicular to the compressed air pipe, located at the top of the compressed air pipe, with their bottoms connected to the compressed air pipe and their sides connected to the crystallization reaction zone. The Venturi tubes are symmetrically arranged along the reactor's axis. Along the reactor's radial direction, from the axis away from the reactor to the axis closer to the reactor, the height of the Venturi tubes decreases, and the height of the position where the Venturi tube connects to the crystallization reaction zone decreases. Multiple hydrocyclones are provided, each corresponding to a venturi tube. The top of each venturi tube is connected to a hydrocyclone. The bottom of each hydrocyclone is located in the crystallization reaction zone, and the top of each hydrocyclone is located in the mixing zone.

2. The calcium fluoride reaction crystallization apparatus according to claim 1, characterized in that, The reactor's inner cavity includes a turbidity control zone, which includes an interconnected particle flocculation zone and a particle settling zone. The particle flocculation zone is connected to the first outlet. The reactor is equipped with a flocculant addition pipe, which is connected to the particle flocculation zone and is used to add flocculant to the particle flocculation zone; the effluent from the particle flocculation zone undergoes particle settling in the particle settling zone. The reactor is equipped with a sludge outlet pipe, which is connected to the particle settling zone and is used to discharge sludge from the turbidity control zone. The top of the particle settling zone is provided with a second outlet, which is used to discharge the supernatant of the particle settling zone.

3. The calcium fluoride reaction crystallization apparatus according to claim 2, characterized in that, The reactor's inner cavity includes an effluent detection zone located at the top of the turbidity control zone, and the second outlet is connected to the effluent detection zone; the reactor is equipped with an effluent pipe connected to the effluent detection zone and also connected to the outside of the reactor. Also includes: The water inlet tank is connected to the water inlet pump and an external wastewater source, and the water inlet pump is connected to the first water inlet pipe and the second water inlet pipe. The drug inlet box is connected to both a drug inlet pump and an external drug source. The drug inlet pump is connected to both the first drug inlet pipe and the second drug inlet pipe. The reactor is equipped with a first return water pipe, which is connected to the effluent detection area, the second inlet water pipe, the first inlet water pipe and the inlet water tank respectively. The reactor is equipped with a second return water pipe, which is connected to the effluent detection area, the second inlet pipe, the first inlet pipe, and the inlet tank.

4. The calcium fluoride reaction crystallization apparatus according to claim 3, characterized in that, Also includes: A first suspended solids detector is configured to detect the concentration of suspended solids in the liquid in the effluent detection zone; A first fluoride ion detector is configured to detect the fluoride ion concentration in the liquid in the effluent detection zone; A first pH detector is configured to detect the pH of the liquid in the water outlet detection zone; A fourth suspended solids detector is configured to detect the concentration of suspended solids in the third mixture; The controller is electrically connected to the first suspended solids detector, the first fluoride ion detector, the first pH detector, and the fourth suspended solids detector. The controller is configured to: If the suspended solids concentration in the liquid in the effluent detection zone is greater than the fifth preset value, and the suspended solids concentration in the third mixture is greater than the sixth preset value, then the amount of second seed crystals discharged from the second seed tube into the fluidized crystallization zone is increased; at the same time, the effluent pipe is closed. If the suspended solids concentration in the effluent detection zone is greater than the fifth preset value, and the suspended solids concentration in the third mixture is not greater than the sixth preset value, then the amount of flocculant added to the particulate flocculation zone through the flocculant addition pipe is increased; at the same time, the effluent pipe is closed. If the concentration of suspended solids in the liquid in the effluent detection zone is not greater than the fifth preset value, then the flocculant addition tube is kept unchanged.

5. The calcium fluoride reactive crystallization apparatus according to claim 4, characterized in that, The controller is configured as follows: When the pH of the liquid in the effluent detection zone is greater than the second preset value, and the fluoride ion concentration of the liquid in the effluent detection zone is greater than the fourth preset value, the amount of the second agent discharged from the second inlet pipe to the fluidized crystallization zone is increased, and the amount of acidic solution discharged from the acid inlet pipe to the mixing zone is increased; at the same time, the effluent pipe is closed. When the pH of the liquid in the effluent detection zone is greater than the second preset value, and the fluoride ion concentration of the liquid in the effluent detection zone is not greater than the fourth preset value, the amount of the second agent discharged from the second inlet pipe to the fluidized crystallization zone is reduced, or the amount of acidic solution discharged from the acid inlet pipe to the mixing zone is increased; at the same time, the effluent pipe is closed. When the pH of the liquid in the effluent detection zone is less than the third preset value, and the fluoride ion concentration of the liquid in the effluent detection zone is greater than the fourth preset value, the amount of the second agent discharged from the second inlet pipe into the fluidized crystallization zone is increased; at the same time, the effluent pipe is closed. When the pH of the liquid in the effluent detection zone is less than the third preset value, and the fluoride ion concentration of the liquid in the effluent detection zone is not greater than the fourth preset value, the amount of acidic solution discharged from the acid inlet pipe to the mixing zone is reduced, or the amount of the second agent discharged from the second inlet pipe to the fluidized crystallization zone is increased; at the same time, the effluent pipe is closed. When the pH of the liquid in the effluent detection zone is not greater than the second preset value and not less than the third preset value, the discharge rates of the second drug inlet pipe and the acid inlet pipe are kept constant.

6. The calcium fluoride reactive crystallization apparatus according to claim 5, characterized in that, include: A second suspended solids detector is configured to detect the concentration of suspended solids in the crystallization reaction zone; A first particle size analyzer is configured to detect the size distribution of calcium fluoride crystals in the crystallization reaction zone; The second pH detector is configured to detect the pH of the second mixture; A third suspended solids detector is configured to detect the concentration of suspended solids in the fluidized crystallization zone; The second particle size analyzer is configured to detect the size distribution of calcium fluoride crystals in the fluidized crystallization zone; The second fluoride ion detector is configured to detect the fluoride ion concentration in the liquid in the water inlet tank; The second suspended solids detector, the first particle size analyzer, the second pH detector, the third suspended solids detector, the second particle size analyzer, and the second fluoride ion detector are all electrically connected to the controller; The controller is configured to automatically calculate the seed surface area load for fluorine in the crystallization reaction zone based on the suspended solids concentration, the size distribution of calcium fluoride crystals in the crystallization reaction zone, and the fluoride ion concentration in the liquid; and to automatically calculate the seed surface area load for fluorine in the fluidized crystallization zone based on the suspended solids concentration, the size distribution of calcium fluoride crystals in the fluidized crystallization zone, and the fluoride ion concentration. The switching frequencies of the first seed tube and the first product outlet tube are controlled according to the seed surface area load of fluorine in the crystallization reaction zone. The switching frequencies of the second seed tube and the second product outlet tube are also controlled according to the seed surface area load of fluorine in the fluidized crystallization zone.

7. The calcium fluoride reactive crystallization apparatus according to any one of claims 1 to 6, characterized in that, The diameter of the second seed crystal is not less than the diameter of the first seed crystal; The fluoride concentration in the first mixture is greater than the fluoride concentration in the second mixture; The surface area load of fluorine seed crystals in the crystallization reaction zone is greater than that in the fluidized crystallization zone.

8. The calcium fluoride reactive crystallization apparatus according to claim 7, characterized in that, The diameter of the second seed crystal is 40 to 50 micrometers; the diameter of the first seed crystal is 25 to 50 micrometers. The fluoride concentration in the first mixture is 600 to 1000 mg / L; the fluoride concentration in the second mixture is 100 to 200 mg / L. The seed surface area loading for fluorine in the crystallization reaction zone is 3 to 4 g / (m²). 2 h); the seed surface area loading for fluorine in the fluidized crystallization zone is 1.5 to 3 g / (m²). 2 h).

9. The calcium fluoride reactive crystallization apparatus according to any one of claims 1 to 6, characterized in that, It also includes a stirring blade, which is located in the crystallization reaction zone and is rotatably connected to the reactor; The first water inlet pipe and the first medicine inlet pipe are located on opposite sides of the stirring blade, and the first water inlet pipe and the first medicine inlet pipe are at different heights. The stirring blade rotates under the action of the first wastewater sprayed from the first water inlet pipe and the first medicine sprayed from the first medicine inlet pipe.

10. The calcium fluoride reactive crystallization apparatus according to claim 9, characterized in that, The stirring blades are provided with multiple drag-reducing holes; And / or, the first water inlet pipe is provided with a plurality of spaced-apart cavities, the diameter of which decreases and then increases from the direction closer to the stirring blade to the direction farther away from the stirring blade; And / or, the first drug inlet tube is provided with multiple spaced cavities, the diameter of which decreases and then increases from the direction near the stirring blade to the direction away from the stirring blade.

11. The calcium fluoride reactive crystallization apparatus according to claim 4, characterized in that, A first control valve is installed on the outlet pipe of the first product; The calcium fluoride reaction crystallization apparatus also includes a weight detector, which is located at the bottom of the reactor. The weight detector is configured to detect the weight of calcium fluoride crystals with a diameter not less than a first preset size. Both the weight detector and the first control valve are electrically connected to the controller. The controller is configured to open the first control valve when the weight is greater than a preset weight, so that the calcium fluoride crystals not smaller than a first preset size can be discharged.

12. The calcium fluoride reactive crystallization apparatus according to any one of claims 1 to 6, characterized in that, Also includes: A liquid distribution plate is located inside the reactor to separate the mixing zone and the fluidized crystallization zone. The liquid distribution plate is provided with a connecting port that connects the mixing zone and the fluidized crystallization zone. A fluidized bed inclined plate is located on top of the liquid distribution plate and is arranged around the periphery of the communication port. The inner wall of the fluidized bed inclined plate is inclined, and the height of the inner wall of the fluidized bed inclined plate increases from the center of the fluidized bed inclined plate to the periphery. A flow guide tube is located inside the fluidized bed inclined plate. The bottom of the flow guide tube has a gap with the inner wall of the fluidized bed inclined plate. The second drug inlet tube and the second seed tube are both connected to the interior of the flow guide tube.

13. A method for controlling a calcium fluoride reactive crystallization apparatus, characterized in that, The method for the calcium fluoride reactive crystallization apparatus according to any one of claims 1 to 12 comprises: A first reagent, a first seed crystal, and a first wastewater are added to the crystallization reaction zone of the reactor; a second wastewater and an acidic solution are added to the mixing zone of the reactor; a second reagent and a second seed crystal are added to the fluidized crystallization zone of the reactor. The calcium fluoride crystals with a diameter not less than the first preset size generated in the crystallization reaction zone fall into the bottom of the reactor and are discharged through the first product outlet pipe; The first mixture in the crystallization reaction zone enters the separation component, which allows calcium fluoride crystals with a diameter smaller than the first preset size and not smaller than the second preset size to enter the crystallization reaction zone, and calcium fluoride crystals with a diameter smaller than the second preset size to enter the mixing zone. Calcium fluoride crystals smaller than the second preset size dissolve in the mixing zone; The liquid in the mixing zone enters the fluidized crystallization zone, the calcium fluoride crystals generated in the fluidized crystallization zone are discharged through the second product outlet pipe, and the third mixed liquid generated in the fluidized crystallization zone is discharged through the first outlet.

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