A composite defluorination agent for lithium mica ore dressing wastewater and its preparation method and application

Abstract

The invention discloses a composite defluoridation agent for lithium mica ore dressing wastewater and its preparation method and application, including a primary defluoridation agent and a secondary defluoridation agent added in two steps; the components of the primary defluoridation agent include: 55-80 parts of defluoridation agent, 10-20 parts of adsorption decomposition agent, 5-10 parts of clarifier, 5-10 parts of neutralizer, and 0-5 parts of buffer; the components of the secondary defluoridation agent include: 60-85 parts of defluoridation agent, 5-10 parts of adsorption decomposition agent, 10-15 parts of clarifier, 0-5 parts of neutralizer, and 0-10 parts of buffer. The composite defluoridation agent in the present invention can destroy the complex system of fluorosilicate, so that it can form an insoluble fluoride precipitate with the defluoridation agent and be removed, and by the method of using two-stage defluoridation agents in combination, the problem of fluoride ions being difficult to remove in lithium mica ore dressing wastewater is solved, so that the fluoride ions of the treated effluent are stably up to standard.

Description

Technical Field

[0001] The invention relates to the technical field of fluorine-containing wastewater treatment, and in particular to a composite defluorination agent for lepidolite ore dressing wastewater, and a preparation method and application thereof. Background Art

[0002] With the development of new energy industry and lithium battery technology, the demand for lithium is increasing, and the development of domestic lithium mines is accelerating. The grade of lithium mica ore is usually 0.3-0.6%, and the lithium dioxide content can reach 2.0-3.5% after concentrate mining. A certain amount of production wastewater will be generated during the mining process. Most of the production wastewater is recycled after treatment in the factory, and a small part is discharged. The production wastewater contains a certain concentration of fluoride. Excessive fluoride ions can cause serious harm to the human body. Therefore, for the sustainable development of the enterprise and the need for environmental protection around the enterprise, it is very important to treat the fluoride ions in the lithium mica ore dressing wastewater up to standard.

[0003] In the prior art, when removing fluoride from wastewater, calcium hydroxide, calcium chloride and other calcium-based defluoridants are generally used for precipitation, so that fluoride ions and calcium ions form insoluble calcium fluoride precipitates and are removed. Since lithium mica ore dressing wastewater is highly alkaline, acid is generally added during treatment to adjust its pH to neutral. At the same time, lithium mica ore dressing wastewater contains a large amount of silicates. Under neutral conditions, silicates and fluorides will form fluorosilicate complexes, which will affect 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 the water can be reduced from 39 mg / L to 10 mg / L; according to relevant experiments and reports, the actual dosage must be greater than the theoretical value, and the calcium chloride dosage must reach 300 mg / L to achieve the above removal rate. As for the complexed fluoride ions in the lepidolite beneficiation wastewater, when the calcium chloride dosage reaches 2500 mg / L, the fluoride ions are only reduced from 39 mg / L to 36.5 mg / L. Regardless of the treatment effect, economy, or environmental friendliness, the calcium fluoride precipitation method is difficult to be used for the treatment of lepidolite beneficiation wastewater. Summary of the invention

[0004] The present invention aims to overcome the problem that the existing calcium fluoride precipitation method is difficult to be used for the treatment of lepidolite ore dressing wastewater, and provides a composite defluoridation agent for lepidolite ore dressing wastewater, and a preparation method and application thereof. The composite defluoridation agent in the present invention can destroy the complex system of fluorosilicate, so that it can form an insoluble fluoride precipitate with the defluoridation agent and be removed, and solves the problem that fluoride ions in lepidolite ore dressing wastewater are difficult to remove by using two-stage defluoridation agents in combination, so that the fluoride ions in the treated effluent are stably up to the standard.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention discloses a composite defluorination agent for lithium mica ore dressing wastewater, comprising a primary defluorination agent and a secondary defluorination agent added in two steps; in parts by weight, the components of the primary defluorination agent include: 55-80 parts of defluorination agent, 10-20 parts of adsorption and decomposition agent, 5-10 parts of clarifier, 5-10 parts of neutralizer, and 0-5 parts of buffer; the components of the secondary defluorination agent include: 60-85 parts of defluorination agent, 5-10 parts of adsorption and decomposition agent, 10-15 parts of clarifier, 0-5 parts of neutralizer, and 0-10 parts of buffer;

[0007] The defluoridating agent is selected from one or more of calcium salts, aluminum salts, and iron salts; the adsorption decomplexing agent is porous calcium carbonate loaded with sodium hydroxide modified by octadecyltrimethylammonium chloride; the clarifier is selected from one or more of polyaluminum chloride, polyaluminum sulfate, polyferric sulfate, and polyaluminum ferric chloride; and the neutralizing agent is an acidic reagent.

[0008] The present invention adds a neutralizing agent and a buffering agent to the defluorination agent, and the pH of the alkaline lithium mica ore dressing wastewater can be adjusted to a suitable discharge and defluorination range; the defluorination agent in the defluorination agent can react with the fluoride ions in the wastewater to form insoluble substances, and accelerate precipitation under the action of a clarifier to remove the fluoride ions in the wastewater. In order to further remove the fluoride ions in the complexes such as fluorosilicates in the wastewater, the present invention adds porous calcium carbonate loaded with sodium hydroxide modified by octadecyltrimethylammonium chloride as an adsorption decomposition agent to the defluorination agent, and a part of the fluorosilicate can be adsorbed and removed by the porous calcium carbonate. At the same time, when the fluorosilicate in the wastewater contacts with the adsorption decomposition agent, it can react with the sodium hydroxide loaded thereon on its surface, destroy its complex system, and generate fluoride ions. The fluoride ions after decomposition can combine with the defluorination agent to form precipitation, and are precipitated and removed under the action of a clarifier. The present invention loads sodium hydroxide on porous calcium carbonate, so that the reaction between sodium hydroxide and fluorosilicate can be carried out on the surface and pores of the porous calcium carbonate, thereby avoiding the influence of direct addition of sodium hydroxide on the pH value of wastewater, affecting the discharge of wastewater up to standard, and avoiding the direct neutralization reaction of sodium hydroxide with a neutralizer, which affects the wastewater treatment effect; at the same time, the porous calcium carbonate can not only be used as an adsorbent to adsorb and remove fluorosilicate in the wastewater, but also react with fluoride ions in the wastewater to replace the fluoride ions with carbonate (CaCO3(s)+2F - (aq)→CaF2(s)+CO3 2- (aq)), and the defluoridation agent works together to improve the fluoride ion removal effect. In order to prevent the porous calcium carbonate from dissolving after contacting with the neutralizer, the present invention uses octadecyl trimethyl ammonium chloride to modify it. The modification of the surface organic matter can improve the acid resistance of the porous calcium carbonate and prevent it from dissolving under the action of the neutralizer.

[0009] At the same time, the present invention divides the defluorination agent into a primary defluorination agent and a secondary defluorination agent and adds them in two steps. The dosage of the defluorination agent, the adsorption decomplexing agent and the clarifier in the primary defluorination agent and the secondary defluorination agent is adjusted according to the properties of the lepidolite ore dressing wastewater, so as to obtain a better defluorination effect and ensure that the fluoride ion concentration of the treated lepidolite ore dressing wastewater can meet the discharge requirement of less than 5 mg / L.

[0010] Preferably, the defluoridating agent is selected from one or more of aluminum ferric sulfate, potassium aluminum sulfate, calcium chloride, calcium carbonate, aluminum chloride, and ferric chloride; the clarifier is selected from one or more of polyaluminum chloride, polyaluminum sulfate, polyferric sulfate, and polyaluminum ferric chloride; the neutralizer is sulfuric acid and / or hydrochloric acid; the buffer is selected from one or more of disodium hydrogen phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, citric acid, and sodium bicarbonate.

[0011] In a second aspect, the present invention discloses a method for preparing a composite defluorination agent for the above-mentioned lepidolite ore dressing wastewater, comprising the following steps:

[0012] A) preparing an adsorption decomplexing agent: adding porous calcium carbonate to a sodium hydroxide solution, ultrasonically impregnating, and then filtering to obtain a porous calcium carbonate loaded with sodium hydroxide; adding octadecyltrimethylammonium chloride to ethanol, stirring evenly to obtain an octadecyltrimethylammonium chloride solution; then adding the porous calcium carbonate loaded with sodium hydroxide to the octadecyltrimethylammonium chloride solution, stirring for reaction, filtering, washing, and drying the product to obtain an adsorption decomplexing agent;

[0013] B) Mix the defluoridation agent, adsorption decomplexing agent, clarifier, neutralizer and buffer in proportion to obtain a primary defluoridation agent and a secondary defluoridation agent.

[0014] Preferably, the mass ratio of porous calcium carbonate, sodium hydroxide and octadecyl trimethyl ammonium chloride added in step A) is 10:1-3:0.1-0.5. The present invention controls the amount of porous calcium carbonate and octadecyl trimethyl ammonium chloride, which can effectively prevent the porous calcium carbonate from contacting and dissolving with the neutralizer, and can also enable the fluorosilicate in the wastewater to react with the sodium hydroxide loaded thereon, and remove the complexed fluorine in the fluorosilicate. If the amount of octadecyl trimethyl ammonium chloride is too small, the protective effect on porous calcium carbonate is insufficient, and porous calcium carbonate is easy to react and dissolve with the neutralizer; if the amount of octadecyl trimethyl ammonium chloride is too large, the adsorption of the complex breaking agent is strong, which is not conducive to contact reaction with the fluorosilicate in the wastewater.

[0015] In a third aspect, the present invention discloses an application of the composite defluorination agent for lithium mica ore dressing wastewater in the treatment of lithium mica ore dressing wastewater, comprising the following steps:

[0016] (1) adding a primary defluorination agent to the lepidolite beneficiation wastewater to carry out a primary defluorination reaction;

[0017] (2) adding a flocculant to the wastewater after the primary defluorination reaction to carry out a primary flocculation reaction;

[0018] (3) After the primary flocculation reaction, a primary sedimentation is performed, and after the mud and water are separated, a secondary defluorination agent is added to the supernatant to perform a secondary defluorination reaction;

[0019] (4) adding a flocculant to the wastewater after the secondary defluorination reaction to carry out a secondary flocculation reaction;

[0020] (5) After the secondary flocculation reaction, secondary sedimentation is carried out, and the fluoride ion content in the supernatant after mud and water separation meets the discharge requirements.

[0021] Preferably, in step (1), the dosage of the primary defluorination agent is 1 to 3 kg / m 3 Wastewater, reaction time is 15 to 25 minutes.

[0022] Preferably, the flocculant in step (2) is a PAM solution with a mass fraction of 1 to 5‰, and the dosage of PAM is 3 to 8 g / m 3 Wastewater, reaction time is 2 to 10 minutes.

[0023] Preferably, in step (3), the dosage of the secondary defluorination agent is 1 to 3 kg / m 3 Wastewater, reaction time is 15 to 25 minutes.

[0024] Preferably, the flocculant in step (4) is a PAM solution with a mass fraction of 1 to 5‰, and the dosage of PAM is 3 to 8 g / m 3 Wastewater, reaction time is 2 to 10 minutes.

[0025] Preferably, the fluoride ion content in the supernatant of step (5) is less than 5 mg / L.

[0026] Therefore, the present invention has the following beneficial effects:

[0027] (1) Adding an adsorbent to the defluorination agent can adsorb the fluorosilicate in the lithium mica ore dressing wastewater and destroy its complex system, so that it can form an insoluble fluoride precipitate with the defluorination agent and be removed;

[0028] (2) By loading sodium hydroxide on porous calcium carbonate, the reaction between sodium hydroxide and fluorosilicate can be carried out on the surface and in the pores of the porous calcium carbonate, thereby avoiding the direct addition of sodium hydroxide to affect the pH of the wastewater and affect the discharge of the wastewater in compliance with the standards, and also avoiding the direct neutralization reaction of sodium hydroxide with the neutralizer, which affects the wastewater treatment effect;

[0029] (3) The porous calcium carbonate loaded with sodium hydroxide is modified with octadecyltrimethylammonium chloride. The modification of the surface organic matter can improve the acid resistance of the porous calcium carbonate and prevent it from dissolving under the action of the neutralizer;

[0030] (4) The defluorination agent is divided into a primary defluorination agent and a secondary defluorination agent and added in two steps, and the dosage of each component in the primary defluorination agent and the secondary defluorination agent is adjusted to obtain a better defluorination effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a flow chart for treating lithium mica ore dressing wastewater using the composite defluorination agent of the present invention.

[0032] In the figure: 1 wastewater tank, 2 primary defluorination reaction box, 3 primary flocculation reaction box, 4 primary sedimentation tank, 5 primary defluorination dosing box, 6 primary flocculation dosing box, 7 secondary defluorination reaction box, 8 secondary flocculation reaction box, 9 secondary sedimentation tank, 10 secondary defluorination dosing box, 11 secondary flocculation dosing box, 12 sludge collection tank, 13 sludge dewatering machine. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described in detail below through specific embodiments. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any form of modification and / or change made to the present invention will fall within the protection scope of the present invention.

[0034] In the present invention, unless otherwise specified, all parts and percentages are 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 embodiments, unless otherwise specified, are conventional methods in the art. The components or equipment in the following embodiments, unless otherwise specified, are universal standard parts or components known to those skilled in the art, and their structures and principles are known to those skilled in the art through technical manuals or conventional experimental methods.

[0035] Overall embodiment:

[0036] A composite defluoridation agent for lithium mica ore dressing wastewater, comprising a primary defluoridation agent and a secondary defluoridation agent added in two steps; in parts by weight, the components of the primary defluoridation agent include: 55-80 parts of defluoridation agent, 10-20 parts of adsorption and decomposition agent, 5-10 parts of clarifier, 5-10 parts of neutralizer, and 0-5 parts of buffer; the components of the secondary defluoridation agent include: 60-85 parts of defluoridation agent, 5-10 parts of adsorption and decomposition agent, 10-15 parts of clarifier, 0-5 parts of neutralizer, and 0-10 parts of buffer;

[0037] The defluoridating agent is selected from one or more of calcium salts, aluminum salts, and iron salts; the adsorption decomplexing agent is porous calcium carbonate loaded with sodium hydroxide modified by octadecyltrimethylammonium chloride; the clarifier is selected from one or more of polyaluminum chloride, polyaluminum sulfate, polyferric sulfate, and polyaluminum ferric chloride; and the neutralizing agent is an acidic reagent.

[0038] As a specific embodiment, the defluorination agent is selected from one or more of aluminum ferric sulfate, potassium aluminum sulfate, calcium chloride, calcium carbonate, aluminum chloride, and ferric chloride; the clarifier is selected from one or more of polyaluminum chloride, polyaluminum sulfate, polyferric sulfate, and polyaluminum ferric chloride; the neutralizer is sulfuric acid and / or hydrochloric acid; the buffer is selected from one or more of disodium hydrogen phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, citric acid, and sodium bicarbonate.

[0039] The preparation method of the composite defluorination agent for lithium mica ore dressing wastewater comprises the following steps:

[0040] A) preparing an adsorption decomplexing agent: adding porous calcium carbonate to a sodium hydroxide solution, ultrasonically impregnating, and then filtering to obtain a porous calcium carbonate loaded with sodium hydroxide; adding octadecyltrimethylammonium chloride to ethanol, stirring evenly to obtain an octadecyltrimethylammonium chloride solution; then adding the porous calcium carbonate loaded with sodium hydroxide to the octadecyltrimethylammonium chloride solution, stirring for reaction, filtering, washing, and drying the product to obtain an adsorption decomplexing agent;

[0041] B) Mix the defluoridation agent, adsorption decomplexing agent, clarifier, neutralizer and buffer in proportion to obtain a primary defluoridation agent and a secondary defluoridation agent.

[0042] As a specific implementation manner, the mass ratio of porous calcium carbonate, sodium hydroxide and octadecyltrimethylammonium chloride added in step A) is 10:1-3:0.1-0.5.

[0043] The application of the composite defluorination agent for lithium mica ore dressing wastewater in the treatment of lithium mica ore dressing wastewater is as follows: Figure 1 As shown in , the following steps are included:

[0044] (1) Lepidolite beneficiation wastewater enters the primary defluorination reaction box 2 through the wastewater pool 1, and a primary defluorination agent is added to the wastewater through the primary defluorination dosing box 5 to perform a primary defluorination reaction;

[0045] (2) After the primary defluorination reaction, the wastewater enters the primary flocculation reaction box 3, and the flocculant is added through the primary flocculation dosing box 6 to carry out the primary flocculation reaction;

[0046] (3) After the primary flocculation reaction, the wastewater and the formed alum flocs enter the primary sedimentation tank 4 for primary sedimentation. After the mud and water are separated, the sludge is discharged into the sludge collection tank 12, and then the sludge is dehydrated by the sludge dewatering machine 13 and disposed together with the tailings. The wastewater generated by the sludge dehydration is returned to the wastewater tank for further treatment; the supernatant enters the secondary defluorination reaction box 7, and the secondary defluorination agent is added to the wastewater through the secondary defluorination dosing box 10 to carry out the secondary defluorination reaction;

[0047] (4) After the secondary defluorination reaction, the wastewater enters the secondary flocculation reaction box 8, and flocculants are added through the secondary flocculation dosing box 11 to carry out the secondary flocculation reaction;

[0048] (5) After the secondary flocculation reaction, the wastewater and the formed alum flocs enter the secondary sedimentation tank 9 for secondary sedimentation. The fluoride ion content in the supernatant after the mud and water separation meets the discharge requirements. The sludge enters the sludge collection tank 12 and then passes through the sludge dewatering machine 13 for dehydration.

[0049] As a specific implementation method, in step (1), the dosage of the primary defluorination agent is 1 to 3 kg / m 3 Wastewater, reaction time is 15 to 25 minutes.

[0050] As a specific implementation method, the flocculant in step (2) is a PAM solution with a mass fraction of 1 to 5‰, and the dosage of PAM is 3 to 8 g / m 3 Wastewater, reaction time is 2 to 10 minutes.

[0051] As a specific implementation, in step (3), the dosage of the secondary defluorination agent is 1 to 3 kg / m 3 Wastewater, reaction time is 15 to 25 minutes.

[0052] As a specific implementation method, the flocculant in step (4) is a PAM solution with a mass fraction of 1 to 5‰, and the dosage of PAM is 3 to 8 g / m 3 Wastewater, reaction time is 2 to 10 minutes.

[0053] As a specific implementation, the fluoride ion content in the supernatant of step (5) is less than 5 mg / L.

[0054] Embodiment 1:

[0055] A composite defluoridation agent for lithium mica ore dressing wastewater comprises a primary defluoridation agent and a secondary defluoridation agent which are added in two steps; in parts by weight, the components of the primary defluoridation agent include: 75 parts of calcium chloride, 17 parts of an adsorbing complex-breaking agent, 8 parts of polyaluminium chloride, 8 parts of hydrochloric acid, and 2 parts of disodium hydrogen phosphate; the components of the secondary defluoridation agent include: 75 parts of calcium chloride, 5 parts of an adsorbing complex-breaking agent, 10 parts of polyaluminium chloride, 3 parts of hydrochloric acid, and 7 parts of disodium hydrogen phosphate.

[0056] The preparation method of the composite defluorination agent for the above-mentioned lepidolite ore dressing wastewater is as follows:

[0057] A) Preparation of adsorption decomplexing agent: adding porous calcium carbonate (particle size 5 μm) to a sodium hydroxide solution with a concentration of 5 wt%, ultrasonically impregnating for 2 hours, and filtering to obtain porous calcium carbonate loaded with sodium hydroxide; adding octadecyltrimethylammonium chloride to ethanol, stirring evenly to obtain an octadecyltrimethylammonium chloride solution with a concentration of 1 wt%; then adding the porous calcium carbonate loaded with sodium hydroxide to the octadecyltrimethylammonium chloride solution, stirring at 50° C. for 3 hours, filtering, washing, and drying the product to obtain an adsorption decomplexing agent; the mass ratio of the added porous calcium carbonate, sodium hydroxide, and octadecyltrimethylammonium chloride is 10:2:0.3;

[0058] B) Mixing the components of the primary defluorination agent and the secondary defluorination agent in proportion to obtain the primary defluorination agent and the secondary defluorination agent.

[0059] The composite defluorination agent is used for treating the lepidolite ore dressing wastewater, comprising the following steps:

[0060] (1) The lithium mica beneficiation wastewater (fluoride ion content of 39 mg / L, pH 10.25, conductivity of 3931 μs / cm) enters the primary defluorination reaction box through the wastewater pool. The primary defluorination agent is added to the wastewater through the primary defluorination dosing box at a dosage of 2.25 kg / m 3 The wastewater was subjected to primary defluorination reaction under stirring in a mixer, the reaction residence time was 20 minutes, and the pH value of the wastewater was adjusted to 6.8;

[0061] (2) After the primary defluorination reaction, the wastewater enters the primary flocculation reaction tank, and the flocculant (3wt‰ polyacrylamide (PAM) solution) is added through the primary flocculation dosing box. The PAM dosage is 5g / m 3 Wastewater, and stirred to carry out primary flocculation reaction, the reaction residence time is 5 minutes;

[0062] (3) After the primary flocculation reaction, the wastewater and the formed alum flocs enter the primary sedimentation tank for primary sedimentation. The surface load of the primary sedimentation tank is 0.8m 3 / m 2 h, the sludge after primary sedimentation is discharged into the sludge collection tank, and then the sludge is dehydrated by the sludge dewatering machine and disposed together with the tailings. The wastewater generated by sludge dehydration is returned to the wastewater tank for further treatment; the fluoride ion concentration of the effluent from the primary sedimentation tank is shown in Table 1;

[0063] (4) The supernatant obtained from the primary precipitation enters the secondary defluorination reaction box, and the secondary defluorination agent is added to the wastewater through the secondary defluorination dosing box, with a dosage of 2.25 kg / m 3The wastewater was subjected to secondary defluorination reaction under stirring in a mixer, the reaction residence time was 20 minutes, and the pH value of the wastewater was 6.8;

[0064] (5) After the secondary defluorination reaction, the wastewater enters the secondary flocculation reaction box, and the flocculant (3wt‰ polyacrylamide (PAM) solution) is added through the secondary flocculation dosing box. The PAM dosage is 5g / m 3 Wastewater, and stirred for secondary flocculation reaction, the reaction residence time was 5 minutes;

[0065] (6) After the secondary flocculation reaction, the wastewater and the formed alum flocs enter the secondary sedimentation tank for secondary sedimentation. The surface load of the secondary sedimentation tank is 0.8m 3 / m 2 ·h. The fluoride ion content in the effluent after secondary sedimentation is shown in Table 1, which meets the discharge requirements. The sludge enters the sludge collection tank and is then dehydrated by the sludge dewatering machine.

[0066] Embodiment 2:

[0067] A composite defluoridation agent for lithium mica ore dressing wastewater comprises a primary defluoridation agent and a secondary defluoridation agent which are added in two steps; in parts by weight, the components of the primary defluoridation agent include: 55 parts of calcium chloride, 20 parts of an adsorbing complex-breaking agent, 10 parts of polyaluminium chloride, 10 parts of hydrochloric acid, and 5 parts of disodium hydrogen phosphate; the components of the secondary defluoridation agent include: 85 parts of calcium chloride, 5 parts of an adsorbing complex-breaking agent, 10 parts of polyaluminium chloride, 2 parts of hydrochloric acid, and 3 parts of disodium hydrogen phosphate.

[0068] The preparation method of the composite defluorination agent for the above-mentioned lepidolite ore dressing wastewater is as follows:

[0069] A) Preparation of adsorption decomplexing agent: adding porous calcium carbonate (particle size 5 μm) to a sodium hydroxide solution with a concentration of 5 wt%, ultrasonically impregnating for 2 hours, and filtering to obtain porous calcium carbonate loaded with sodium hydroxide; adding octadecyltrimethylammonium chloride to ethanol, stirring evenly to obtain an octadecyltrimethylammonium chloride solution with a concentration of 1 wt%; then adding the porous calcium carbonate loaded with sodium hydroxide to the octadecyltrimethylammonium chloride solution, stirring at 50° C. for 3 hours, filtering, washing, and drying the product to obtain an adsorption decomplexing agent; the mass ratio of the added porous calcium carbonate, sodium hydroxide, and octadecyltrimethylammonium chloride is 10:1:0.1;

[0070] B) Mixing the components of the primary defluorination agent and the secondary defluorination agent in proportion to obtain the primary defluorination agent and the secondary defluorination agent.

[0071] The composite defluorination agent is used for treating the lepidolite ore dressing wastewater, comprising the following steps:

[0072] (1) The lithium mica beneficiation wastewater (fluoride ion content of 20.5 mg / L, pH of 10.12, and conductivity of 2037 μs / cm) enters the primary defluorination reaction box through the wastewater pool. The primary defluorination agent is added to the wastewater through the primary defluorination dosing box at a dosage of 1.25 kg / m 3 The wastewater was subjected to primary defluorination reaction under stirring in a mixer, the reaction residence time was 20 minutes, and the pH value of the wastewater was adjusted to 6.7;

[0073] (2) After the primary defluorination reaction, the wastewater enters the primary flocculation reaction tank, and the flocculant (3wt‰ polyacrylamide (PAM) solution) is added through the primary flocculation dosing box. The PAM dosage is 5g / m 3 Wastewater, and stirred to carry out primary flocculation reaction, the reaction residence time is 5 minutes;

[0074] (3) After the primary flocculation reaction, the wastewater and the formed alum flocs enter the primary sedimentation tank for primary sedimentation. The surface load of the primary sedimentation tank is 0.8m 3 / m 2 h, the sludge after primary sedimentation is discharged into the sludge collection tank, and then the sludge is dehydrated by the sludge dewatering machine and disposed together with the tailings. The wastewater generated by sludge dehydration is returned to the wastewater tank for further treatment; the fluoride ion concentration of the effluent from the primary sedimentation tank is shown in Table 1;

[0075] (4) The supernatant obtained from the primary precipitation enters the secondary defluorination reaction box, and the secondary defluorination agent is added to the wastewater through the secondary defluorination dosing box, with a dosage of 1.25 kg / m 3 The wastewater was subjected to secondary defluorination reaction under stirring in a mixer, the reaction residence time was 20 minutes, and the pH value of the wastewater was 6.7;

[0076] (5) After the secondary defluorination reaction, the wastewater enters the secondary flocculation reaction box, and the flocculant (3wt‰ polyacrylamide (PAM) solution) is added through the secondary flocculation dosing box. The PAM dosage is 5g / m 3 Wastewater, and stirred for secondary flocculation reaction, the reaction residence time was 5 minutes;

[0077] (6) After the secondary flocculation reaction, the wastewater and the formed alum flocs enter the secondary sedimentation tank for secondary sedimentation. The surface load of the secondary sedimentation tank is 0.8m 3 / m 2 ·h. The fluoride ion content in the effluent after secondary sedimentation is shown in Table 1, which meets the discharge requirements. The sludge enters the sludge collection tank and is then dehydrated by the sludge dewatering machine.

[0078] Embodiment 3:

[0079] A composite defluoridation agent for lithium mica ore dressing wastewater comprises a primary defluoridation agent and a secondary defluoridation agent which are added in two steps; in parts by weight, the components of the primary defluoridation agent include: 80 parts of aluminum chloride, 10 parts of an adsorbing complex-breaking agent, 5 parts of polyaluminum chloride, 5 parts of hydrochloric acid, and 2 parts of disodium hydrogen phosphate; the components of the secondary defluoridation agent include: 60 parts of calcium chloride, 10 parts of an adsorbing complex-breaking agent, 15 parts of polyaluminum chloride, 5 parts of hydrochloric acid, and 10 parts of disodium hydrogen phosphate.

[0080] The preparation method of the composite defluorination agent for the above-mentioned lepidolite ore dressing wastewater is as follows:

[0081] A) Preparation of adsorption decomplexing agent: adding porous calcium carbonate (particle size 5 μm) to a sodium hydroxide solution with a concentration of 5 wt%, ultrasonically impregnating for 2 hours, and filtering to obtain porous calcium carbonate loaded with sodium hydroxide; adding octadecyltrimethylammonium chloride to ethanol, stirring evenly to obtain an octadecyltrimethylammonium chloride solution with a concentration of 1 wt%; then adding the porous calcium carbonate loaded with sodium hydroxide to the octadecyltrimethylammonium chloride solution, stirring at 50° C. for 3 hours, filtering, washing, and drying the product to obtain an adsorption decomplexing agent; the mass ratio of the added porous calcium carbonate, sodium hydroxide, and octadecyltrimethylammonium chloride is 10:3:0.5;

[0082] B) Mixing the components of the primary defluorination agent and the secondary defluorination agent in proportion to obtain the primary defluorination agent and the secondary defluorination agent.

[0083] The composite defluorination agent is used for treating the lepidolite ore dressing wastewater, comprising the following steps:

[0084] (1) The lithium mica beneficiation wastewater (fluoride ion content of 42.0 mg / L, pH 10.3, conductivity of 4210 μs / cm) enters the primary defluorination reaction box through the wastewater pool. The primary defluorination agent is added to the wastewater through the primary defluorination dosing box at a dosage of 2.25 kg / m 3 The wastewater was subjected to primary defluorination reaction under stirring in a mixer, the reaction residence time was 20 minutes, and the pH value of the wastewater was adjusted to 6.7;

[0085] (2) After the primary defluorination reaction, the wastewater enters the primary flocculation reaction tank, and the flocculant (3wt‰ polyacrylamide (PAM) solution) is added through the primary flocculation dosing box. The PAM dosage is 5g / m 3 Wastewater, and stirred to carry out primary flocculation reaction, the reaction residence time is 5 minutes;

[0086] (3) After the primary flocculation reaction, the wastewater and the formed alum flocs enter the primary sedimentation tank for primary sedimentation. The surface load of the primary sedimentation tank is 0.8m 3 / m 2h, the sludge after primary sedimentation is discharged into the sludge collection tank, and then the sludge is dehydrated by the sludge dewatering machine and disposed together with the tailings. The wastewater generated by sludge dehydration is returned to the wastewater tank for further treatment; the fluoride ion concentration of the effluent from the primary sedimentation tank is shown in Table 1;

[0087] (4) The supernatant obtained from the primary precipitation enters the secondary defluorination reaction box, and the secondary defluorination agent is added to the wastewater through the secondary defluorination dosing box, with a dosage of 2.25 kg / m 3 The wastewater was subjected to secondary defluorination reaction under stirring in a mixer, the reaction residence time was 20 minutes, and the pH value of the wastewater was 6.7;

[0088] (5) After the secondary defluorination reaction, the wastewater enters the secondary flocculation reaction box, and the flocculant (3wt‰ polyacrylamide (PAM) solution) is added through the secondary flocculation dosing box. The PAM dosage is 5g / m 3 Wastewater, and stirred for secondary flocculation reaction, the reaction residence time was 5 minutes;

[0089] (6) After the secondary flocculation reaction, the wastewater and the formed alum flocs enter the secondary sedimentation tank for secondary sedimentation. The surface load of the secondary sedimentation tank is 0.8m 3 / m 2 ·h. The fluoride ion content in the effluent after secondary sedimentation is shown in Table 1, which meets the discharge requirements. The sludge enters the sludge collection tank and is then dehydrated by the sludge dewatering machine.

[0090] Comparative Example 1 (without adding adsorption decomposition agent):

[0091] A composite defluoridation agent for lithium mica ore dressing wastewater, comprising a primary defluoridation agent and a secondary defluoridation agent added in two steps; in parts by weight, the components of the primary defluoridation agent include: 75 parts of calcium chloride and 8 parts of polyaluminium chloride; the components of the secondary defluoridation agent include: 75 parts of calcium chloride and 10 parts of polyaluminium chloride;

[0092] The method for treating lithium mica ore dressing wastewater is the same as that in Example 1.

[0093] Comparative Example 2 (porous calcium carbonate does not load sodium hydroxide):

[0094] The difference between Comparative Example 2 and Example 1 is that the preparation method of the adsorption decomposition agent is as follows: octadecyl trimethyl ammonium chloride is added to ethanol, and stirred evenly to obtain an octadecyl trimethyl ammonium chloride solution with a concentration of 1wt%; then porous calcium carbonate (particle size 5μm) is added to the octadecyl trimethyl ammonium chloride solution, and the product is filtered, washed, and dried after stirring at 50°C for 3h to obtain an adsorption decomposition agent; the mass ratio of the added porous calcium carbonate to the octadecyl trimethyl ammonium chloride is 10:0.3;

[0095] The rest are the same as in Example 1.

[0096] Comparative Example 3 (porous calcium carbonate is not modified by octadecyltrimethylammonium chloride):

[0097] The difference between Comparative Example 3 and Example 1 is that the preparation method of the adsorption decomposition agent is as follows: porous calcium carbonate (particle size 5 μm) is added to a sodium hydroxide solution with a concentration of 5wt%, and after ultrasonic immersion for 2 hours, the product is filtered, washed, and dried to obtain the adsorption decomposition agent; the mass ratio of the added porous calcium carbonate to the sodium hydroxide is 10:2;

[0098] The rest are the same as in Example 1.

[0099] Comparative Example 4 (excessive use of octadecyltrimethylammonium chloride):

[0100] The difference between Comparative Example 4 and Example 1 is that the preparation method of the adsorption decomplexing agent is as follows: adding porous calcium carbonate (particle size 5 μm) to a sodium hydroxide solution with a concentration of 5wt%, ultrasonically immersing for 2h and then filtering to obtain a porous calcium carbonate loaded with sodium hydroxide; adding octadecyltrimethylammonium chloride to ethanol, stirring evenly to obtain an octadecyltrimethylammonium chloride solution with a concentration of 1wt%; then adding the porous calcium carbonate loaded with sodium hydroxide to the octadecyltrimethylammonium chloride solution, stirring the reaction at 50°C for 3h, filtering, washing and drying the product to obtain an adsorption decomplexing agent; the mass ratio of the added porous calcium carbonate, sodium hydroxide and octadecyltrimethylammonium chloride is 10:2:1;

[0101] Table 1: Fluoride ion removal effect in lithium mica beneficiation wastewater.

[0102]

[0103] As can be seen from Table 1, in Examples 1 to 3, the method of the present invention is adopted, an adsorbent decomplexing agent is added to the defluorination agent, and the primary defluorination agent and the secondary defluorination agent are distributed and added, the total removal rate of fluoride ions is high, and the fluoride ion content of the effluent is less than the discharge requirement of 5 mg / L.

[0104] In Comparative Example 1, no adsorbent decomplexing agent is added to the defluorination agent, the fluorosilicate complex in the lithium mica beneficiation wastewater cannot be destroyed, and the fluoride ions are difficult to form precipitation with calcium ions for removal. The fluoride ion removal rate is significantly lower than that in the embodiment, and the fluoride ion content of the effluent cannot meet the discharge requirements.

[0105] In the adsorption decomplexing agent of Comparative Example 2, sodium hydroxide is not loaded on the surface of the porous calcium carbonate. The porous calcium carbonate can only physically adsorb the fluorosilicate in the wastewater, and cannot destroy the complex system of the fluorosilicate by chemical reaction to release fluoride ions and react with the defluorinating agent to form a precipitate for removal; the defluorination effect is reduced compared with that in the embodiment.

[0106] In Comparative Example 3, octadecyltrimethylammonium chloride is not used to modify the porous calcium carbonate loaded with sodium hydroxide. The porous calcium carbonate is easily dissolved in contact with the neutralizer, which destroys the porous structure on its surface, reduces the adsorption of fluorosilicate in the wastewater, and the defluorination effect is also reduced compared with that in the embodiment.

[0107] In Comparative Example 4, too much octadecyltrimethylammonium chloride was added during the modification, and the hydrophobicity of the porous calcium carbonate surface was too strong, which was not conducive to its adsorption and contact reaction with fluorosilicate in wastewater. The defluorination effect was also reduced compared with that in the example.

[0108] Although specific embodiments have been used to illustrate the invention, it is understood that the above embodiments are used to understand the methods and core matters of the present invention and cannot be understood as limitations on the present invention. A person of ordinary skill in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose 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 deemed to be within the protection scope of the present invention.

Claims

1. A composite defluorination agent for lithium mica ore dressing wastewater, characterized in that: The invention comprises a primary defluoridation agent and a secondary defluoridation agent added in two steps; in parts by weight, the components of the primary defluoridation agent include: 55-80 parts of defluoridation agent, 10-20 parts of adsorption and decomposition agent, 5-10 parts of clarifier, 5-10 parts of neutralizer, and 0-5 parts of buffer; the components of the secondary defluoridation agent include: 60-85 parts of defluoridation agent, 5-10 parts of adsorption and decomposition agent, 10-15 parts of clarifier, 0-5 parts of neutralizer, and 0-10 parts of buffer; The defluoridating agent is selected from one or more of calcium salts, aluminum salts, and iron salts; the adsorption decomplexing agent is porous calcium carbonate loaded with sodium hydroxide modified by octadecyltrimethylammonium chloride; the clarifier is selected from one or more of polyaluminum chloride, polyaluminum sulfate, polyferric sulfate, and polyaluminum ferric chloride; and the neutralizing agent is an acidic reagent.

2. The composite defluorination agent for lithium mica ore dressing wastewater according to claim 1, characterized in that: The defluoridating agent is selected from one or more of aluminum ferric sulfate, potassium aluminum sulfate, calcium chloride, calcium carbonate, aluminum chloride, and ferric chloride; the neutralizing agent is sulfuric acid and / or hydrochloric acid; the buffer is selected from one or more of disodium hydrogen phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, citric acid, and sodium bicarbonate.

3. A method for preparing a composite defluorination agent for lithium mica ore dressing wastewater as claimed in claim 1 or 2, characterized in that: The steps include: A) preparing an adsorbent decomplexing agent: adding porous calcium carbonate to a sodium hydroxide solution, ultrasonically impregnating, and then filtering to obtain a porous calcium carbonate loaded with sodium hydroxide; adding octadecyltrimethylammonium chloride to ethanol, stirring evenly to obtain an octadecyltrimethylammonium chloride solution; then adding the porous calcium carbonate loaded with sodium hydroxide to the octadecyltrimethylammonium chloride solution, stirring for reaction, filtering, washing, and drying the product to obtain an adsorbent decomplexing agent; B) Mix the defluoridation agent, adsorption decomplexing agent, clarifier, neutralizer and buffer in proportion to obtain a primary defluoridation agent and a secondary defluoridation agent.

4. The preparation method according to claim 3, characterized in that: The mass ratio of porous calcium carbonate, sodium hydroxide and octadecyltrimethylammonium chloride added in step A) is 10:1-3:0.1-0.

5.

5. An application of the composite defluorination agent for lithium mica ore dressing wastewater as claimed in claim 1 or 2 in the treatment of lithium mica ore dressing wastewater, characterized in that: The steps include: (1) Adding a primary defluorination agent to the lepidolite beneficiation wastewater to carry out a primary defluorination reaction; (2) After the primary defluorination reaction, a flocculant is added to the wastewater to carry out a primary flocculation reaction; (3) After the primary flocculation reaction, a primary sedimentation is performed, and after the mud and water are separated, a secondary defluorination agent is added to the supernatant to perform a secondary defluorination reaction; (4) After the secondary defluorination reaction, a flocculant is added to the wastewater to carry out a secondary flocculation reaction; (5) After the secondary flocculation reaction, secondary sedimentation is carried out, and the fluoride ion content in the supernatant after mud and water separation meets the discharge requirements.

6. The use according to claim 5, characterized in that: In step (1), the dosage of the primary defluoridation agent is 1-3 kg / m 3 Wastewater, reaction time is 15~25min.

7. The use according to claim 5, characterized in that: The flocculant in step (2) is a PAM solution with a mass fraction of 1-5‰, and the dosage of PAM is 3-8 g / m 3 Wastewater, reaction time is 2~10min.

8. The use according to claim 5, characterized in that: In step (3), the dosage of the secondary defluorination agent is 1~3 kg / m 3 Wastewater, reaction time is 15~25min.

9. The use according to claim 5, characterized in that: The flocculant in step (4) is a PAM solution with a mass fraction of 1-5‰, and the dosage of PAM is 3-8 g / m 3 Wastewater, reaction time is 2~10min.

10. The use according to claim 5, characterized in that: The fluoride ion content in the supernatant of step (5) is less than 5 mg / L.

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