A device and method for removing fluorine from spodumene ore dressing wastewater

Abstract

The present invention discloses a device and method for defluorination of lithium mica ore dressing wastewater, including a defluorination reaction unit, a coagulation precipitation unit and a precipitation separation unit; the reaction unit includes a pH adjustment area and a defluorination reaction area; the coagulation precipitation unit includes a coagulation reaction area and a flocculation reaction area; the precipitation separation unit is an inclined tube precipitation area; the pH adjustment area is connected to a hydrochloric acid dosing device; the defluorination reaction area is connected to a defluorinating agent dosing device; the defluorinating agent dosing device is provided with a defluorinating agent, and the defluorinating agent includes a precipitant and an adsorption and complex-breaking agent, and the adsorption and complex-breaking agent is porous calcium carbonate loaded with NaOH and AlCl3; the coagulation reaction area is connected to a PAC dosing device; the flocculation reaction area is connected to a PAM dosing device. The present invention reasonably arranges each reaction area in the defluorination device, optimizes the defluorination reaction process, and improves the defluorination effect on lithium mica ore dressing wastewater; an adsorption and complex-breaking agent is added to the defluorinating agent, solving the problem that it is difficult to remove fluorine in fluorosilicic acid complexes.

Description

Technical Field

[0001] The present invention relates to the technical field of fluorine-containing wastewater treatment, and particularly to a device and method for removing fluorine from spodumene ore dressing wastewater. Background Art

[0002] In recent years, with the rapid development of the new energy industry and low-carbon economy, especially the breakthrough and popularization of large-capacity power battery technology, the new energy vehicle industry has risen rapidly, the demand for lithium products has been increasing day by day, and the market demand for lithium has increased sharply. Most of the world's lithium resources come from spodumene and salt lake brine. However, due to the current development of the new energy industry and lithium battery technology, the demand for lithium is increasing day by day, and the limited spodumene and salt lake brine resources may face depletion and supply shortages, and the distribution of spodumene and salt lake brine resources is extremely unbalanced. There are also a large amount of lithium resources stored in ores, and spodumene is one of the lithium-rich ores. China has the largest spodumene ore reserve in Asia. Although the process of extracting lithium from lithium ore is complex and energy-consuming, the reserves of lithium-containing ores are quite rich, so spodumene ore is still one of the important resources for lithium extraction.

[0003] A certain amount of production wastewater will be generated during the beneficiation process of spodumene. Most of the production wastewater is recycled after being treated in the factory, and a small part is discharged externally. The production wastewater contains a certain concentration of fluoride. Exceeding the standard of fluoride will cause the death of aquatic organisms and the destruction of the ecological balance. Long-term drinking of water with excessive fluoride may lead to fluorosis, which has a serious impact on human health. Therefore, before discharging externally, it is necessary to remove fluorine from spodumene ore dressing wastewater.

[0004] In the prior art, when removing fluorine from wastewater, the calcium-based defluorination agent precipitation method using calcium hydroxide, calcium chloride, etc. is generally adopted, so that fluoride ions form insoluble calcium fluoride precipitation with calcium ions and are removed. Since the lithium mica beneficiation wastewater is strongly alkaline, acid is generally added during treatment to adjust its pH to neutral. At the same time, the lithium mica beneficiation wastewater contains more silicates. Under neutral conditions, silicates and fluorides will form fluorosilicate complexes, thus affecting the precipitation of fluoride ions and calcium ions in the wastewater. For free fluoride ions, theoretically when the calcium chloride dosage reaches 100 mg / L, the fluoride ion concentration in water can be reduced from 39 mg / L to 10 mg / L; according to relevant tests and reports, the actual dosage should be greater than the theoretical value, and the calcium chloride dosage needs to reach 300 mg / L to achieve the above removal rate. For the complexed fluoride ions in the lithium mica beneficiation wastewater, when the calcium chloride dosage reaches 2500 mg / L, its fluoride ions are only reduced from 39 mg / L to 36.5 mg / L. Considering from the aspects of treatment effect, economy, and environmental friendliness, the calcium fluoride precipitation method is difficult to be used for the treatment of lithium mica beneficiation wastewater. In addition, for the defluorination of lithium mica beneficiation wastewater, in addition to adding a special defluorination agent, it is also necessary to control parameters such as the pH of the reaction, the defluorination reaction time, the dosing nodes of the coagulant and flocculant aid, the flocculation reaction time, and the surface load of the sedimentation tank. Therefore, a special device suitable for the defluorination treatment of lithium mica beneficiation wastewater is needed. Summary of the Invention

[0005] The present invention is to overcome the above problems existing in the treatment of lithium mica beneficiation wastewater in the prior art, and provides a lithium mica beneficiation wastewater defluorination device and a defluorination method, which reasonably layout each reaction zone in the defluorination device, optimize the defluorination reaction process, and improve the defluorination effect on lithium mica beneficiation wastewater; an adsorption and complex-breaking agent is added to the defluorination agent, solving the problem that it is difficult to remove fluorine in fluorosilicate complexes.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A lithium mica beneficiation wastewater defluorination device includes a defluorination reaction unit, a coagulation and precipitation unit, and a precipitation separation unit; the reaction unit includes a pH adjustment zone and a defluorination reaction zone connected by a pipeline; the coagulation and precipitation unit includes a coagulation reaction zone and a flocculation reaction zone connected by a pipeline, and the coagulation reaction zone is connected to the defluorination reaction zone by a pipeline; the precipitation separation unit includes an inclined tube sedimentation zone connected to the flocculation reaction zone;

[0008] The pH adjustment zone is connected to a hydrochloric acid dosing device;

[0009] The defluorination reaction zone is connected to a defluorination agent dosing device; the defluorination agent dosing device is provided with a defluorination agent, and the defluorination agent includes a precipitant and an adsorption and complex-breaking agent. The precipitant is a calcium salt, and the adsorption and complex-breaking agent is loaded with NaOH and AlCl3 porous calcium carbonate;

[0010] The coagulation reaction zone is connected to the PAC dosing device;

[0011] The flocculation reaction zone is connected to the PAM dosing device.

[0012] When treating lepidolite ore dressing wastewater with the device in the present invention, the wastewater successively passes through the pH adjustment zone, the defluorination reaction zone, the coagulation reaction zone, the flocculation reaction zone and the inclined tube sedimentation zone. After pH adjustment, defluorination reaction and coagulation precipitation, the fluoride ions in the wastewater are removed. Finally, after sedimentation in the inclined tube sedimentation zone, the fluoride ion concentration in the effluent can meet the discharge requirement of less than 5 mg / L.

[0013] In the present invention, hydrochloric acid is first added in the pH adjustment zone to adjust the pH of the alkaline lepidolite ore dressing wastewater to a suitable range for discharge and defluorination. Then, a defluorinating agent is added in the defluorination reaction zone. The precipitant in the defluorinating agent can react with the fluoride ions in the wastewater to form insoluble substances, and under the action of the coagulant PAC added in the subsequent coagulation reaction zone and the flocculant PAM added in the flocculation reaction zone, the precipitation is accelerated to remove the fluoride ions in the wastewater by precipitation. In order to further remove the fluoride ions in the complex compounds such as fluorosilicates in the wastewater, a porous calcium carbonate loaded with NaOH and AlCl 3 is used as an adsorption and complex-breaking agent in the defluorinating agent. Part of the fluorosilicates can be adsorbed and removed by the porous calcium carbonate. At the same time, when the fluorosilicates in the wastewater contact the adsorption and complex-breaking agent, they can react with the sodium hydroxide loaded on its surface to destroy its complex system and generate fluoride ions. The fluoride ions after complex-breaking can combine with the precipitant to form a precipitate, and are removed by precipitation under the action of the coagulant and flocculant added in the subsequent coagulation reaction zone and flocculation reaction zone. In the present invention, sodium hydroxide is loaded on the porous calcium carbonate, which can make the reaction between sodium hydroxide and fluorosilicates occur on the surface and in the pores of the porous calcium carbonate, avoiding the direct addition of sodium hydroxide from affecting the pH of the wastewater and affecting the up-to-standard discharge of the wastewater. At the same time, the porous calcium carbonate can not only be used as an adsorbent to adsorb and remove the fluorosilicates in the wastewater, but also react with the fluoride ions in the wastewater to replace the fluoride ions with carbonate radicals (CaCO 3 (s)+2F - (aq)→CaF 2 (s)+CO 3 2- (aq)), and cooperate with the precipitant to improve the fluoride ion removal effect. At the same time, in order to further improve the fluoride ion removal effect and make the fluoride ion concentration in the effluent meet the discharge requirement of less than 5 mg / L, AlCl 3 is also loaded on the porous calcium carbonate, and AlCl 3It can react with the fluoride ions generated after the reaction of fluorosilicate with sodium hydroxide, further accelerating their removal and ensuring that the removal effect of fluoride ions meets the discharge requirements.

[0014] Preferably, the preparation method of the adsorption and complex-breaking agent is as follows: Add porous calcium carbonate into sodium hydroxide solution, filter and wash it after ultrasonic impregnation to obtain porous calcium carbonate loaded with sodium hydroxide; then add the porous calcium carbonate loaded with sodium hydroxide into aluminum chloride solution, filter, wash and dry the product after ultrasonic impregnation to obtain the adsorption and complex-breaking agent.

[0015] Preferably, the mass ratio of the added porous calcium carbonate, sodium hydroxide and aluminum chloride is 10:2-4:0.5-1.

[0016] Preferably, an on-line pH meter is provided in the pH adjustment area, and a hydrochloric acid dosing pump is provided on the pipeline connecting the hydrochloric acid dosing device to the pH adjustment area. The on-line pH meter and the hydrochloric acid dosing pump are interlocked for control. Setting an on-line pH meter in the pH adjustment area and interlocking it with the hydrochloric acid dosing pump can on-line monitor and adjust the pH value of the wastewater in the pH adjustment area, so that the pH value of the wastewater remains in a suitable range for discharge and defluorination.

[0017] Preferably, a pipeline mixer is provided on the pipeline between the pH adjustment area and the defluorination reaction area, and the front section of the pipeline mixer is connected to the defluorination agent dosing device through a pipeline. Mixing the defluorination agent and the wastewater in advance through the pipeline mixer is conducive to the uniform mixing of the defluorination agent and the wastewater, ensuring the defluorination effect of the wastewater.

[0018] Preferably, the coagulation and sedimentation unit includes two coagulation reaction areas, both of which are connected to the defluorination reaction area through pipelines, and the flocculation reaction area is located between the two coagulation reaction areas. Setting a coagulation reaction area on each side of the flocculation reaction area can reduce the volume of the device while ensuring the coagulation and sedimentation effect.

[0019] Preferably, a rapid stirrer is provided in the pH adjustment area, the defluorination reaction area and the coagulation reaction area, and a slow stirrer is provided in the flocculation reaction area. Rapid stirring in the pH adjustment area and the defluorination reaction area is conducive to the uniform mixing of hydrochloric acid and the defluorination agent with the wastewater, ensuring the defluorination effect. Rapid stirring in the coagulation reaction area and slow stirring in the flocculation reaction area are conducive to the sedimentation and separation of the precipitate.

[0020] The present invention also discloses a method for removing fluoride from lepidolite ore dressing wastewater, which is carried out using the above-mentioned device for removing fluoride from lepidolite ore dressing wastewater, and includes the following steps:

[0021] (1) The lepidolite ore dressing wastewater enters the pH adjustment area, and hydrochloric acid is added to adjust the pH of the wastewater;

[0022] (2) Then it enters the defluorination reaction area, and a defluorination agent is added for defluorination reaction;

[0023] (3) Then enter the coagulation reaction zone, and add PAC for coagulation precipitation;

[0024] (4) Then enter the flocculation reaction zone, and add PAM for flocculation precipitation;

[0025] (5) Finally, enter the inclined tube sedimentation zone for sedimentation, and the supernatant is discharged.

[0026] Preferably, in step (1), the pH of the wastewater is adjusted to 6.0 - 7.5; the stirring speed in the pH adjustment zone is 120 - 130 r / min.

[0027] Preferably, in the defluorinating agent added in step (2), the dosage of the precipitant is 1500 - 3000 mg / L, and the dosage of the adsorption and complex-breaking agent is 1200 - 2500 mg / L; the residence time in the defluorination reaction zone is 10 - 20 min, and the stirring speed is 70 - 90 r / min.

[0028] Preferably, in step (3), the dosage of PAC is 40 - 60 mg / L, the residence time in the coagulation reaction zone is 8 - 15 min, and the stirring speed is 70 - 90 r / min.

[0029] Preferably, in step (4), the dosage of PAM is 3 - 10 mg / L, the residence time in the flocculation reaction zone is 3 - 8 min, and the stirring speed is 40 - 50 r / min.

[0030] Preferably, the surface loading of the inclined tube sedimentation zone is 1 - 2 m 3 / m 2 ·h.

[0031] Therefore, the present invention has the following beneficial effects:

[0032] (1) Reasonably layout each reaction zone in the defluorination device, optimize the defluorination reaction process, and improve the defluorination effect on the lithium mica ore dressing wastewater;

[0033] (2) Add an adsorption and complex-breaking agent to the defluorinating agent, and solve the problem that it is difficult to remove fluorine in the fluorosilicate complex. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic structural diagram of the lithium mica ore dressing wastewater defluorination device of the present invention.

[0035] In the figure: 1 - pH adjustment area, 2 - defluorination reaction area, 3 - coagulation reaction area, 4 - flocculation reaction area, 5 - inclined tube sedimentation area, 6 - hydrochloric acid dosing device, 7 - defluorinating agent dosing device, 8 - PAC dosing device, 9 - PAM dosing device, 10 - on-line pH meter, 11 - hydrochloric acid dosing pump, 12 - water inlet, 13 - pipe mixer, 14 - first connecting pipe, 15 - second connecting pipe, 16 - third connecting pipe, 17 - water outlet, 18 - sludge discharge port, 19 - sludge discharge pump. Specific embodiments

[0036] The following are specific examples to further illustrate the technical solutions of the present invention. It should be understood that the implementation of the present invention is not limited to the following examples, and any formal modification and / or change made to the present invention will fall within the protection scope of the present invention.

[0037] In the present invention, unless otherwise specified, all parts and percentages are in weight units, and the equipment and raw materials used can be purchased from the market or are commonly used in the art. The methods in the following examples are conventional methods in the art unless otherwise specified. The components or equipment in the following examples are general standard parts or components known to those skilled in the art, and their structures and principles can be known by those skilled in the art through technical manuals or obtained through conventional experimental methods.

[0038] General embodiment:

[0039] A device for removing fluorine from spodumene ore dressing wastewater, as Figure 1 shown, includes a defluorination reaction unit, a coagulation sedimentation unit and a sediment separation unit arranged in sequence from left to right.

[0040] The reaction unit includes a pH adjustment area 1 and a defluorination reaction area 2 connected through a first connecting pipe 14; the pH adjustment area is connected to a hydrochloric acid dosing device 6; an on-line pH meter 10 is provided in the pH adjustment area, and a hydrochloric acid dosing pump 11 is provided on the pipeline connecting the hydrochloric acid dosing device to the pH adjustment area, and the on-line pH meter is interlocked with the hydrochloric acid dosing pump for control. A pipe mixer 13 is provided on the first connecting pipe 14, and the front section of the pipe mixer is connected to a defluorinating agent dosing device 7 through a pipeline; a defluorinating agent is provided in the defluorinating agent dosing device, and the defluorinating agent includes a precipitant and an adsorption and complex-breaking agent. The precipitant is a calcium salt, and the adsorption and complex-breaking agent is porous calcium carbonate loaded with NaOH and AlCl 3 3; rapid stirrers are respectively provided in the pH adjustment area and the defluorination reaction area.

[0041] The coagulation and sedimentation unit includes two coagulation reaction zones 3 and a flocculation reaction zone 4. The two coagulation reaction zones 3 are communicated with the defluorination reaction zone 2 through a third connecting pipe 16. The flocculation reaction zone 4 is located between the two coagulation reaction zones. The two coagulation reaction zones 3 are communicated with the defluorination reaction zone 2 through a T-shaped second connecting pipe 15. The main pipe of the second connecting pipe is connected to the PAC dosing device 8 through a pipeline. The flocculation reaction zone 4 is connected to the PAM dosing device 9 through a pipeline. A rapid stirrer is provided in the coagulation reaction zone, and a slow stirrer is provided in the flocculation reaction zone.

[0042] The precipitation separation unit includes an inclined tube sedimentation zone 5 communicated with the flocculation reaction zone 4. The top of the inclined tube sedimentation zone is provided with a water outlet 17, and the bottom is provided with a sludge discharge port 18. The sludge discharge port is connected to a sludge discharge pump 19 through a pipeline.

[0043] A method for defluorinating lepidolite ore dressing wastewater using the above defluorination device includes the following steps:

[0044] (1) The lepidolite ore dressing wastewater enters the pH adjustment zone 1 from the water inlet 12, and hydrochloric acid is added through the hydrochloric acid dosing device 6 to adjust the pH of the wastewater.

[0045] (2) Then the wastewater enters the defluorination reaction zone 2 through the first connecting pipe 14, and a defluorinating agent is added by the defluorinating agent dosing device 7 for defluorination reaction.

[0046] (3) Then the wastewater enters the coagulation reaction zone 3 through the second connecting pipe 15, and PAC is added through the PAC dosing device 8 for coagulation and sedimentation.

[0047] (4) Then the wastewater enters the flocculation reaction zone 4 through the third connecting pipe 16, and PAM is added through the PAM dosing device 9 for flocculation and sedimentation.

[0048] (5) Finally, the wastewater enters the inclined tube sedimentation zone 5 for sedimentation, and the supernatant is discharged from the water outlet 17.

[0049] In the present invention, hydrochloric acid is first added in the pH adjustment zone, and the pH of the alkaline lepidolite ore dressing wastewater can be adjusted to a suitable range for discharge and defluorination. Then, a defluorinating agent is added in the defluorination reaction zone. The adsorption and complex-breaking agent in the defluorinating agent can destroy the complex system of fluorosilicates in the wastewater and release fluoride ions. The precipitant can react with the fluoride ions in the wastewater to form an insoluble substance, and the precipitation is accelerated under the action of the coagulant PAC added in the subsequent coagulation reaction zone and the flocculant PAM added in the flocculation reaction zone, so as to remove the fluoride ions in the wastewater by precipitation.

[0050] As a specific embodiment, in step (1), the pH of the wastewater is adjusted to 6.0 - 7.5; the stirring speed in the pH adjustment zone is 120 - 130 r / min.

[0051] As a specific embodiment, in the defluorinating agent added in step (2), the dosage of the precipitant is 1500 - 3000 mg / L, and the dosage of the adsorption and complex-breaking agent is 1200 - 2500 mg / L; the residence time in the defluorination reaction zone is 10 - 20 min, and the stirring speed is 70 - 90 r / min; the preparation method of the adsorption and complex-breaking agent is as follows: adding porous calcium carbonate into sodium hydroxide solution, filtering and washing after ultrasonic impregnation to obtain porous calcium carbonate loaded with sodium hydroxide; then adding the porous calcium carbonate loaded with sodium hydroxide into aluminum chloride solution, filtering, washing and drying the product after ultrasonic impregnation to obtain the adsorption and complex-breaking agent; the mass ratio of the added porous calcium carbonate, sodium hydroxide and aluminum chloride is 10:2 - 4:0.5 - 1.

[0052] As a specific embodiment, in step (3), the dosage of PAC is 40 - 60 mg / L, the residence time in the coagulation reaction zone is 8 - 15 min, and the stirring speed is 70 - 90 r / min.

[0053] As a specific embodiment, in step (4), the dosage of PAM is 3 - 10 mg / L, the residence time in the flocculation reaction zone is 3 - 8 min, and the stirring speed is 40 - 50 r / min.

[0054] As a specific embodiment, the surface load of the inclined tube sedimentation zone is 1 - 2 m 3 / m 2 ·h.

[0055] Example 1:

[0056] A method for defluorinating lepidolite ore dressing wastewater, comprising the following steps:

[0057] (1) The lepidolite ore dressing wastewater (with a fluoride ion content of 39 mg / L, a pH of 10.25, and a conductivity of 3931 μs / cm) enters the pH adjustment zone, hydrochloric acid is added and stirred by a rapid stirrer to adjust the pH of the wastewater to 6.8; the stirring speed is 127 r / min;

[0058] (2) Then it enters the defluorination reaction zone, a defluorinating agent is added, and it is stirred by a rapid stirrer for defluorination reaction; the defluorinating agent includes calcium chloride and an adsorption and complex-breaking agent, the dosage of calcium chloride is 2500 mg / L, and the dosage of the adsorption and complex-breaking agent is 2000 mg / L; the residence time in the defluorination reaction zone is 15 min, and the stirring speed is 82 r / min;

[0059] The preparation method of the adsorption and complex-breaking agent is as follows: Add porous calcium carbonate (particle size 5 μm) into a sodium hydroxide solution with a concentration of 5 wt%, and after ultrasonic impregnation for 2 h, filter and wash to obtain porous calcium carbonate loaded with sodium hydroxide; then add the porous calcium carbonate loaded with sodium hydroxide into an aluminum trichloride solution with a concentration of 2 mol / L, and after ultrasonic impregnation for 2 h, filter, wash, and dry the product to obtain the adsorption and complex-breaking agent; the mass ratio of the added porous calcium carbonate, sodium hydroxide, and aluminum trichloride is 10:3:0.8;

[0060] (3) Then enter the coagulation reaction zone, add PAC, and stir with a rapid stirrer for coagulation precipitation; the dosage of PAC is 50 mg / L, the residence time in the coagulation reaction zone is 10 min, and the stirring speed is 82 r / min;

[0061] (4) Then enter the flocculation reaction zone, add PAM, and stir with a slow stirrer for flocculation precipitation; the dosage of PAM is 5 mg / L, the residence time in the flocculation reaction zone is 5 min, and the stirring speed is 48 r / min;

[0062] (5) Finally, enter the inclined tube sedimentation zone for sedimentation, and the supernatant is discharged. The surface load of the inclined tube sedimentation zone is 1.4 m 3 / ㎡·h.

[0063] Example 2:

[0064] A method for removing fluorine from lepidolite ore dressing wastewater includes the following steps:

[0065] (1) The lepidolite ore dressing wastewater (fluoride ion content is 37 mg / L, pH is 10.17, and conductivity is 3822 μs / cm) enters the pH adjustment zone, add hydrochloric acid and stir with a rapid stirrer to adjust the pH of the wastewater to 6.80; the stirring speed is 127 r / min;

[0066] (2) Then enter the defluorination reaction zone, add a defluorination agent, and stir with a rapid stirrer for defluorination reaction; the defluorination agent includes calcium chloride and an adsorption and complex-breaking agent. The dosage of calcium chloride is 2250 mg / L, and the dosage of the adsorption and complex-breaking agent is 1800 mg / L; the residence time in the defluorination reaction zone is 15 min, and the stirring speed is 82 r / min;

[0067] The preparation method of the adsorption and complex-breaking agent is as follows: Add porous calcium carbonate (particle size 5 μm) into a sodium hydroxide solution with a concentration of 5 wt%, and after ultrasonic impregnation for 2 h, filter and wash to obtain porous calcium carbonate loaded with sodium hydroxide; then add the porous calcium carbonate loaded with sodium hydroxide into an aluminum trichloride solution with a concentration of 2 mol / L, and after ultrasonic impregnation for 2 h, filter, wash, and dry the product to obtain the adsorption and complex-breaking agent; the mass ratio of the added porous calcium carbonate, sodium hydroxide, and aluminum trichloride is 10:2:1;

[0068] (3) Then enter the coagulation reaction zone, add PAC, and stir with a rapid stirrer to carry out coagulation precipitation; the dosage of PAC is 50 mg / L, the residence time in the coagulation reaction zone is 10 min, and the stirring speed is 82 r / min;

[0069] (4) Then enter the flocculation reaction zone, add PAM, and stir with a slow stirrer to carry out flocculation precipitation; the dosage of PAM is 5 mg / L, the residence time in the flocculation reaction zone is 5 min, and the stirring speed is 48 r / min;

[0070] (5) Finally, enter the inclined tube sedimentation zone for sedimentation, and the supernatant is discharged. The surface loading of the inclined tube sedimentation zone is 1.4 m 3 / ㎡·h.

[0071] Example 3:

[0072] A method for removing fluorine from spodumene ore dressing wastewater, comprising the following steps:

[0073] (1) The spodumene ore dressing wastewater (fluoride ion content is 19 mg / L, pH is 9.82, conductivity is 2018 μs / cm) enters the pH adjustment zone, add hydrochloric acid and stir with a rapid stirrer to adjust the pH of the wastewater to 6.80; the stirring speed is 127 r / min;

[0074] (2) Then enter the defluorination reaction zone, add a defluorination agent, and stir with a rapid stirrer to carry out defluorination reaction; the defluorination agent includes calcium chloride and an adsorption and complex-breaking agent. The dosage of calcium chloride is 1500 mg / L, and the dosage of the adsorption and complex-breaking agent is 1200 mg / L; the residence time in the defluorination reaction zone is 15 min, and the stirring speed is 82 r / min;

[0075] The preparation method of the adsorption and complex-breaking agent is: add porous calcium carbonate (particle size 5 μm) to a sodium hydroxide solution with a concentration of 5 wt%, ultrasonically impregnate for 2 h, then filter and wash to obtain porous calcium carbonate loaded with sodium hydroxide; then add the porous calcium carbonate loaded with sodium hydroxide to a aluminum trichloride solution with a concentration of 2 mol / L, ultrasonically impregnate for 2 h, then filter, wash and dry the product to obtain the adsorption and complex-breaking agent; the mass ratio of the added porous calcium carbonate, sodium hydroxide and aluminum trichloride is 10:4:0.5;

[0076] (3) Then enter the coagulation reaction zone, add PAC, and stir with a rapid stirrer to carry out coagulation precipitation; the dosage of PAC is 40 mg / L, the residence time in the coagulation reaction zone is 10 min, and the stirring speed is 82 r / min;

[0077] (4) Then enter the flocculation reaction zone, add PAM, and stir with a slow stirrer for flocculation precipitation; the dosage of PAM is 4 mg / L, the residence time in the flocculation reaction zone is 5 min, and the stirring speed is 48 r / min;

[0078] (5) Finally, enter the inclined tube sedimentation zone for sedimentation, and the supernatant is discharged. The surface load of the inclined tube sedimentation zone is 1.4 m 3 / ㎡·h.

[0079] Comparative Example 1 (no adsorption and complex-breaking agent is added to the defluorinating agent):

[0080] A method for removing fluorine from spodumene ore dressing wastewater includes the following steps:

[0081] (1) Spodumene ore dressing wastewater (fluoride ion content is 39 mg / L, pH is 10.25, conductivity is 3931 μs / cm) enters the pH adjustment zone, add hydrochloric acid and stir with a fast stirrer to adjust the pH of the wastewater to 6.8; the stirring speed is 127 r / min;

[0082] (2) Then enter the defluorination reaction zone, add the defluorinating agent, and stir with a fast stirrer for defluorination reaction; the defluorinating agent is calcium chloride, and the dosage of calcium chloride is 2500 mg / L; the residence time in the defluorination reaction zone is 15 min, and the stirring speed is 82 r / min;

[0083] (3) Then enter the coagulation reaction zone, add PAC, and stir with a fast stirrer for coagulation precipitation; the dosage of PAC is 50 mg / L, the residence time in the coagulation reaction zone is 10 min, and the stirring speed is 82 r / min;

[0084] (4) Then enter the flocculation reaction zone, add PAM, and stir with a slow stirrer for flocculation precipitation; the dosage of PAM is 5 mg / L, the residence time in the flocculation reaction zone is 5 min, and the stirring speed is 48 r / min;

[0085] (5) Finally, enter the inclined tube sedimentation zone for sedimentation, and the supernatant is discharged. The surface load of the inclined tube sedimentation zone is 1.4 m 3 / ㎡·h.

[0086] Comparative Example 2 (porous calcium carbonate is not loaded with sodium hydroxide):

[0087] The difference between Comparative Example 2 and Example 1 is that the preparation method of the adsorption and complex-breaking agent added in step (2) is: add porous calcium carbonate (particle size 5 μm) to aluminum chloride solution with a concentration of 2 mol / L, ultrasonically impregnate for 2 h, then filter, wash, and dry the product to obtain the adsorption and complex-breaking agent; the mass ratio of the added porous calcium carbonate to aluminum chloride is 10:0.8; the rest are the same as in Example 1.

[0088] Comparative Example 3 (porous calcium carbonate not loaded with AlCl 3 ):

[0089] The difference between Comparative Example 3 and Example 1 is that the preparation method of the adsorption and complex-breaking agent added in step (2) is as follows: Porous calcium carbonate (particle size 5 μm) is added to a sodium hydroxide solution with a concentration of 5 wt%, and after ultrasonic impregnation for 2 h, the product is filtered, washed, and dried to obtain the adsorption and complex-breaking agent; the mass ratio of the added porous calcium carbonate to sodium hydroxide is 10:3; the rest are the same as in Example 1.

[0090] Comparative Example 4 (excessive loaded AlCl 3 ):

[0091] The difference between Comparative Example 4 and Example 1 is that the preparation method of the adsorption and complex-breaking agent added in step (2) is as follows: Porous calcium carbonate (particle size 5 μm) is added to a sodium hydroxide solution with a concentration of 5 wt%, and after ultrasonic impregnation for 2 h, it is filtered and washed to obtain porous calcium carbonate loaded with sodium hydroxide; then the porous calcium carbonate loaded with sodium hydroxide is added to an aluminum chloride solution with a concentration of 2 mol / L, and after ultrasonic impregnation for 2 h, the product is filtered, washed, and dried to obtain the adsorption and complex-breaking agent; the mass ratio of the added porous calcium carbonate, sodium hydroxide, and aluminum chloride is 10:3:2; the rest are the same as in Example 1.

[0092] Comparative Example 5 (directly adding AlCl 3 into the wastewater):

[0093] A method for removing fluorine from lepidolite ore dressing wastewater includes the following steps:

[0094] (1) Lepidolite ore dressing wastewater (fluoride ion content is 39 mg / L, pH is 10.25, conductivity is 3931 μs / cm) enters the pH adjustment zone, hydrochloric acid is added and stirred by a rapid stirrer to adjust the pH of the wastewater to 6.8; the stirring speed is 127 r / min;

[0095] (2) Then it enters the defluorination reaction zone, a defluorinating agent is added, and stirred by a rapid stirrer for defluorination reaction; the defluorinating agent includes calcium chloride, aluminum chloride, and an adsorption and complex-breaking agent. The dosage of calcium chloride is 2500 mg / L, the dosage of the adsorption and complex-breaking agent is 1884 mg / L, and the dosage of aluminum chloride is 116 mg / L; the residence time in the defluorination reaction zone is 15 min, and the stirring speed is 82 r / min; the preparation method of the adsorption and complex-breaking agent is: Porous calcium carbonate (particle size 5 μm) is added to a sodium hydroxide solution with a concentration of 5 wt%, and after ultrasonic impregnation for 2 h, the product is filtered, washed, and dried to obtain the adsorption and complex-breaking agent; the mass ratio of the added porous calcium carbonate to sodium hydroxide is 10:3;

[0096] (3) Then enter the coagulation reaction zone, add PAC, and stir with a rapid stirrer for coagulation precipitation; the dosage of PAC is 50 mg / L, the residence time in the coagulation reaction zone is 10 min, and the stirring speed is 82 r / min;

[0097] (4) Then enter the flocculation reaction zone, add PAM, and stir with a slow stirrer for flocculation precipitation; the dosage of PAM is 5 mg / L, the residence time in the flocculation reaction zone is 5 min, and the stirring speed is 48 r / min;

[0098] (5) Finally, enter the inclined tube sedimentation zone for sedimentation, and the supernatant is discharged. The surface loading of the inclined tube sedimentation zone is 1.4 m 3 / ㎡·h.

[0099] The fluoride ion concentrations in the effluent from the inclined tube sedimentation zone in the above-mentioned examples and comparative examples were tested, and the results are shown in Table 1.

[0100] Table 1: Removal effect of fluoride ions in fluorine-containing wastewater from spodumene beneficiation.

[0101]

[0102] As can be seen from Table 1, in Examples 1 to 3, the device and method of the present invention were used to treat spodumene beneficiation wastewater, and the total removal rate of fluoride ions was high, and the fluoride ion content in the effluent was less than the discharge requirement of 5 mg / L.

[0103] In Comparative Example 1, the adsorption and complex-breaking agent was not added to the defluorinating agent, and the fluorosilicate complex in the fluorine-containing wastewater from spodumene beneficiation could not be destroyed, and it was difficult for fluoride ions to form precipitates with calcium ions for removal. The removal rate of fluoride ions decreased significantly compared with that in the examples, and the fluoride ion content in the effluent could not meet the discharge requirements.

[0104] In the adsorption and complex-breaking agent of Comparative Example 2, sodium hydroxide was not surface-loaded on the porous calcium carbonate, and only aluminum trichloride was loaded. The porous calcium carbonate could only physically adsorb the fluorosilicate in the wastewater and could not destroy the complex system of fluorosilicate through chemical reactions to release fluoride ions and react with the defluorinating agent to form precipitates for removal; the defluorination effect decreased compared with that in the examples, and the fluoride ion concentration in the effluent could not meet the discharge requirements.

[0105] In the adsorption and complex-breaking agent of Comparative Example 3, only sodium hydroxide was surface-loaded on the porous calcium carbonate, and aluminum trichloride was not loaded; the removal effect of fluoride ions by aluminum trichloride was missing, and the defluorination effect could not reach the level in the examples either.

[0106] In Comparative Example 4, too much aluminum trichloride was loaded, which would affect the complex-breaking reaction of sodium hydroxide with fluorosilicate, and the defluorination effect also decreased compared with that in the examples.

[0107] In Comparative Example 5, aluminum trichloride was directly added to the wastewater without being loaded on the surface of porous calcium carbonate, and the fluoride removal effect of the wastewater also decreased compared with that in the examples. This shows that loading aluminum trichloride on the surface of porous calcium carbonate and acting together with sodium hydroxide are beneficial to the removal of fluoride ions in the spodumene ore dressing wastewater.

[0108] Although specific embodiments have been used above to illustrate the invention, it can be understood that the above embodiments are for understanding the method and core matters of the present invention and should not be construed as a limitation of the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention without departing from the principles and purposes of the present invention. Any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention shall be regarded as within the protection scope of the present invention.

Claims

1. A fluorine removal device for lithium mica ore dressing wastewater, characterized in that: It includes a defluorination reaction unit, a coagulation sedimentation unit and a sedimentation separation unit; the reaction unit includes a pH adjustment zone and a defluorination reaction zone connected by a pipeline; the coagulation sedimentation unit includes a coagulation reaction zone and a flocculation reaction zone connected by a pipeline, and the coagulation reaction zone is connected to the defluorination reaction zone through a pipeline; the sedimentation separation unit includes an inclined tube sedimentation zone connected to the flocculation reaction zone; The pH adjustment area is connected to the hydrochloric acid dosing device; The defluorination reaction zone is connected to the defluorination agent dosing device; the defluorination agent dosing device is provided with a defluorination agent, the defluorination agent includes a precipitant and an adsorption decomposition agent, the precipitant is a calcium salt, and the adsorption decomposition agent is a porous calcium carbonate loaded with NaOH and AlCl3; the mass ratio of the porous calcium carbonate, sodium hydroxide and aluminum chloride is 10:2~4:0.5~1; The coagulation reaction zone is connected to the PAC dosing device; The flocculation reaction zone is connected to the PAM dosing device.

2. The lepidolite beneficiation wastewater defluorination device according to claim 1, characterized in that: An online pH meter is provided in the pH adjustment area, a hydrochloric acid dosing pump is provided on the pipeline connecting the hydrochloric acid dosing device and the pH adjustment area, and the online pH meter and the hydrochloric acid dosing pump are interlocked and controlled.

3. The lepidolite beneficiation wastewater defluorination device according to claim 1, characterized in that: A pipeline mixer is arranged on the pipeline between the pH adjustment zone and the defluorination reaction zone, and the front section of the pipeline mixer is connected with the defluorination agent dosing device through a pipeline.

4. The fluorine removal device for lithium mica ore dressing wastewater according to claim 1 is characterized in that: The coagulation sedimentation unit comprises two coagulation reaction zones, both of which are connected with the defluorination reaction zone through pipelines, and the flocculation reaction zone is located between the two coagulation reaction zones.

5. The fluorine removal device for lithium mica ore dressing wastewater according to claim 1, 3 or 4, characterized in that: A fast agitator is provided in the pH adjustment zone, the defluorination reaction zone and the coagulation reaction zone, and a slow agitator is provided in the flocculation reaction zone.

6. A method for removing fluorine from lithium mica ore dressing wastewater, characterized in that: The method is carried out using the lepidolite beneficiation wastewater defluorination device as described in any one of claims 1 to 5, comprising the following steps: (1) Lepidolite beneficiation wastewater enters the pH adjustment zone, and hydrochloric acid is added to adjust the pH of the wastewater; (2) Then enter the defluorination reaction zone, add defluorination agent to carry out defluorination reaction; (3) Then it enters the coagulation reaction zone and PAC is added for coagulation and sedimentation; (4) Entering the flocculation reaction zone, adding PAM for flocculation precipitation; (5) Finally, it enters the inclined tube sedimentation area for sedimentation and the supernatant is discharged.

7. The method for defluorinating lithium mica ore dressing wastewater according to claim 6, wherein: In step (1), the pH of the wastewater is adjusted to 6.0-7.5; the stirring speed in the pH adjustment zone is 120-130 r / min.

8. The method for defluorinating lithium mica ore dressing wastewater according to claim 6, wherein: In the defluorination agent added in step (2), the dosage of the precipitant is 1500-3000 mg / L, and the dosage of the adsorption decomplexing agent is 1200-2500 mg / L; the residence time in the defluorination reaction zone is 10-20 min, and the stirring speed is 70-90 r / min.

9. The method for defluorinating lithium mica ore dressing wastewater according to claim 6, wherein: In step (3), the dosage of PAC is 40-60 mg / L, the residence time in the coagulation reaction zone is 8-15 min, and the stirring speed is 70-90 r / min.

10. The method for defluorinating lithium mica ore dressing wastewater according to claim 6, wherein: In step (4), the dosage of PAM is 3-10 mg / L, the residence time in the flocculation reaction zone is 3-8 min, and the stirring speed is 40-50 r / min.

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