Al2o3-zno microspheres for adsorbing fluorine in zinc sulfate solution and preparation method and application thereof

Abstract

The application discloses an adsorbent for removing fluorine from a zinc sulfate solution and a preparation method and application thereof. Step one: dissolving a water-soluble aluminum salt and a water-soluble zinc salt in deionized water to obtain solution A; step two: dissolving a precipitant and [Al 3+ +Zn 2+ ] in deionized water to obtain solution B; step three: mixing solution A and solution B and stirring to obtain solution C; step four: transferring solution C into a high-pressure reaction kettle and reacting; step five: after the reaction in step four is completed, vacuum filtering and washing the precipitate in the reaction kettle in step four, drying and grinding the obtained white precipitate to obtain a precursor; step six: calcining the precursor to generate a grayish-white adsorbent; step seven: adding the adsorbent into an industrial zinc sulfate solution and performing ultrasonic-assisted adsorption by using a stirring paddle; and step eight: after the adsorbent after fluorine removal in step seven is filtered, washed and dried, performing heat regeneration treatment to obtain a regenerated adsorbent. The application can effectively reduce the content of fluorine ions in the zinc sulfate solution.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of zinc sulfate solution purification and defluorination in zinc hydrometallurgy process, and particularly relates to an Al2O3-ZnO microsphere adsorbent for defluorination of zinc sulfate solution and a preparation method and application thereof. BACKGROUND

[0002] The zinc hydrometallurgy process is a leading method for zinc smelting in the world today due to good resource comprehensive utilization, low energy consumption and environmental friendliness. However, with the decrease of zinc concentrate grade and the increase of secondary resource usage, and the continuous enrichment and accumulation of fluoride ions in the electrolyte in the zinc hydrometallurgy system, the fluoride ion content in the solution is getting higher and higher, which seriously affects the normal production of zinc; in the zinc electrolysis deposition stage, the fluoride ions in the solution can damage the oxide film on the surface of the cathode aluminum plate, causing the cathode zinc to be difficult to peel off from the aluminum plate, resulting in problems such as increased labor intensity for peeling zinc, increased frequency of aluminum plate replacement and reduced cathode current efficiency. At the same time, too high fluoride ion content will also increase the corrosion rate of the anode, which not only shortens the service life of the anode plate, but also affects the quality of zinc ingots. In addition, too high fluoride ion content in the zinc sulfate solution will also worsen the working environment and endanger the health of workers. Therefore, the zinc hydrometallurgy industry generally requires that the fluoride ion content in the zinc sulfate solution be controlled below 50 mg / L.

[0003] Among the many methods for removing fluoride ions, the adsorption method has the advantages of simple operation, low reagent price and high efficiency. Among them, aluminum-based adsorbents show good stability and adsorption performance in drinking water, so they are introduced into the research on defluorination of zinc sulfate solution. Existing research shows that the introduction of activated alumina into the defluorination of zinc sulfate solution can exhibit certain adsorption performance. For example, the adsorption capacity of modified aluminum hydroxide in a zinc sulfate simulation solution reaches 3.68 mg / g; a layered aluminum-based composite material synthesized by a "co-precipitation + calcination method" has an adsorption capacity of 5.62 mg / g in an industrial zinc sulfate solution, and when its dosage is greater than 15 g / L, the fluoride ion content is reduced to below 50 mg / L. For industrial applications, the dosage of the adsorbent should be kept at a lower level (or the adsorption capacity should be further improved) to effectively control the production cost.

[0004] In summary, the current aluminum-based adsorbents used for defluorination of zinc sulfate solution have the problems of low adsorption capacity, large adsorbent usage, poor selectivity, and difficulty in further improving the performance of the adsorbent after its preparation, which makes it difficult to be applied in practice and the production cost of enterprises is too high. SUMMARY

[0005] In order to overcome the defects existing in the prior art, the present application aims to provide a kind of adsorbent for removing fluorine from zinc sulfate solution and its preparation method and application, which has the characteristics of unique semi-enclosed structure and structural adjustment during the use of adsorbent, and can achieve the purposes of reducing the dosage of adsorbent, improving the adsorption capacity and enhancing the selectivity.

[0006] In order to achieve the above-mentioned purposes, the technical scheme adopted by the present application is:

[0007] An Al2O3-ZnO microsphere adsorbent for removing fluorine from zinc sulfate solution, which is a semi-enclosed Al2O3 microsphere composed of nanoflower secondary particles of primary ZnO nanosheets, with the outer part composed of ZnO nanosheets and the inner part being Al2O3 microspheres;

[0008] The Al2O3-ZnO microsphere adsorbent includes the following components with the mass percentage:

[0009] 1) the mass ratio of aluminum oxide to zinc oxide is 34.64-44.12%:55.88-65.36%;

[0010] 2) the specific surface area (S BET ) of the adsorbent is 52-301m 2 / g, the pore size distribution is 7.7-18.5nm, the porosity is 0.14-0.39cm 3 / g, the particle size is 1-60μm, and the morphology is a semi-enclosed Al2O3 microsphere composed of nanoflower secondary particles of primary ZnO nanosheets, with the oxygen vacancy content being 0.2-5%.

[0011] A preparation method and application of an Al2O3-ZnO microsphere adsorbent for removing fluorine from zinc sulfate solution, which includes the following steps:

[0012] Step one: dissolve water-soluble aluminum salt and water-soluble zinc salt in deionized water according to the molar ratio of [Al 3+ ]:[Zn 2+ ], and obtain a mixed transparent solution by fully stirring, which is marked as solution A;

[0013] Step two: dissolve a precipitating agent in deionized water according to the molar ratio of precipitating agent:[Al 3+ +Zn 2+ ], and obtain a transparent solution by fully stirring, which is marked as solution B;

[0014] Step three: mix solution A and solution B obtained in steps one and two, and stir to obtain a mixed transparent solution, which is marked as solution C;

[0015] Step four: transfer the mixed solution C obtained in step three into a polytetrafluoroethylene-lined high-pressure reaction kettle for reaction.

[0016] Step five: after the reaction of step four, the precipitate in the reactor of step four is washed by vacuum filtration, the white precipitate is dried and grinded to obtain the precursor;

[0017] Step six: the precursor obtained in step five is calcined under certain conditions to obtain the adsorbent in off-white color;

[0018] Step seven: the adsorbent obtained in step six is added into the industrial zinc sulfate solution and is adsorbed under certain conditions with the aid of ultrasonic and stirring paddle;

[0019] Step eight: the adsorbent after defluorination in step seven is filtered, washed and dried and is subjected to heat regeneration treatment to obtain the regenerated adsorbent, which can be recycled for the operation of step seven.

[0020] Further, the water-soluble aluminum salt in step one is at least one of aluminum sulfate, aluminum nitrate and aluminum chloride, and the water-soluble zinc salt is at least one of zinc sulfate, zinc nitrate, zinc chloride and zinc acetate;

[0021] The water-soluble aluminum salt and the water-soluble zinc salt are dissolved in deionized water at a molar ratio of [Al 3+ ]:[Zn 2+ ] 1:0.25-1.5.

[0022] Further, in step two, the precipitant is dissolved in deionized water at a molar ratio of precipitant:[Al 3+ +Zn 2+ ] 5-40:1, and a transparent solution obtained by sufficient stirring is recorded as solution B; wherein the precipitant is composed of precipitant A and precipitant B at a molar ratio of 0-6:1-4, the precipitant A includes at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonia water, ammonium carbonate and ammonium bicarbonate, and the precipitant B includes at least one of urea and oxalic acid.

[0023] Further, in step three, the mixture is stirred at 25-65℃ for 30-180 min.

[0024] Further, in step four, the mixed solution C obtained in step three is transferred into a polytetrafluoroethylene-lined high-pressure reactor, and is reacted at 120-180℃ for 480-1440 min; the high-pressure reactor used has a specification of 100-300 mL.

[0025] Further, in step five, the washing is performed for 3-6 times, and the washing medium is deionized water, and the drying temperature is 80-100℃.

[0026] Further, the roasting reaction atmosphere in step six is any atmosphere, and the roasting is performed at 350-550 DEG C for 120-480 min.

[0027] Further, the adsorbent obtained in step six is added into the industrial zinc sulfate solution at a liquid-solid ratio of 2-10 g / L, and the ultrasonic-assisted stirring adsorption is performed at 25-80 DEG C, wherein the ultrasonic power is 360-900 W, the rotating speed is 80-180 r / min, and the ultrasonic-assisted stirring adsorption reaction time in step seven is 30-120 min; the stirring paddle blade is at least one of Ag, Co, Mo, Pb, Zr, Al, C, Au, Cu, Si, W, Mg, Ni, Fe, Mn, Ti, or an alloy material comprising the above elements.

[0028] Further, the roasting temperature for the heat regeneration treatment in step eight is 350-550 DEG C, and the roasting time is 120-480 min.

[0029] The adsorbent prepared by the application is applied to zinc sulfate solution and other similar fluorine-containing solutions.

[0030] The application has the following beneficial effects:

[0031] (1) The adsorbent prepared by the application has good affinity for fluorine, good adsorption selectivity and high adsorption capacity (about 15 mg / g, which is 1.5-5 times the adsorption capacity of the existing adsorbent), and can effectively reduce the fluorine ion content in the zinc sulfate solution.

[0032] (2) The preparation method of the adsorbent for removing fluorine from zinc sulfate solution has stable material properties and does not introduce impurities; and in the adsorption process, the weak acidity of the zinc sulfate solution is utilized, the oxygen vacancies are introduced into the adsorbent by the assistance of "ultrasonic + special stirring paddle blade", the surface charge properties are changed, and the performance of the adsorbent is further improved.

[0033] (3) The adsorption and fluorine removal are performed by the method of "stirring + ultrasonic", which changes the traditional adsorption method mainly based on oscillation, increases the diffusion rate of the adsorbent, makes the adsorbent disperse faster in the zinc sulfate solution, shortens the contact time of the adsorbent and fluorine ions, greatly improves the fluorine removal efficiency and adsorption effect, strengthens the purification and fluorine removal process, and keeps the zinc loss rate at a very low level. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The SEM image of the Al2O3-ZnO microspheres and the EDS element mapping of Al, Zn and O elements. DETAILED DESCRIPTION

[0035] The application will be further described in detail below with reference to the drawings.

[0036] An Al2O3-ZnO microsphere adsorbent for defluorination of zinc sulfate solution, comprising or only comprising the following two components in mass percentage:

[0037] 1) alumina: zinc oxide (mass ratio) is 34.64-44.12%: 55.88-65.36%;

[0038] As a preferred solution, alumina: zinc oxide (mass ratio) is 36.44-43.18%: 56.82-63.56%;

[0039] 2) the specific surface area (S BET ) of the adsorbent is 52-301m 2 / g, the pore size distribution is 7.7-18.5nm, the porosity is 0.14-0.39cm 3 / g, the particle size is 1-60μm, and the morphological feature is a "bouquet flower-shaped" ZnO nanoflower secondary particle half-encapsulated Al2O3 microsphere structure assembled by ZnO nanosheets, and the oxygen vacancy content is 0.2-5%.

[0040] As a preferred solution, the defluorination adsorbent has a specific surface area (S BET ) of 55-300m 2 / g, a pore size distribution of 8.0-18.0nm, a porosity of 0.15-0.35cm 3 / g, a particle size of 3-50μm, and an oxygen vacancy content of 0.3-4.8%.

[0041] A preparation method and application of an Al2O3-ZnO microsphere adsorbent for defluorination of zinc sulfate solution, comprising the following steps:

[0042] Step one: dissolve water-soluble aluminum salt and water-soluble zinc salt in 50-150mL deionized water according to [Al 3+ ]:[Zn 2+ ] molar ratio 1:0.25-1.5, and fully stir the obtained mixed transparent solution to obtain solution A;

[0043] Step two: dissolve the precipitant in 50-150mL deionized water according to precipitant:[Al 3+ +Zn 2+ ] molar ratio 5-40:1, and fully stir the obtained transparent solution to obtain solution B; wherein the precipitant is composed of precipitant A and precipitant B according to molar ratio 0-6:1-4, precipitant A includes at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonia, ammonium carbonate, and ammonium bicarbonate, and precipitant B includes at least one of urea and oxalic acid;

[0044] Step three: mix solution A and solution B obtained in step one and step two at 25-65℃, then stir at 80-150 r / min for 30-180 min to obtain a mixed transparent solution, which is recorded as solution C;

[0045] Step four: transfer solution C obtained in step three into a high-pressure reactor with a polytetrafluoroethylene liner, and react at 120-180℃ for 480-1440 min;

[0046] Step five: after the reaction in step four is completed, vacuum filtration and washing are performed on the precipitate in the reactor in step four, and the obtained white precipitate is dried and ground to obtain a precursor;

[0047] Step six: calcine the precursor obtained in step five at 350-550℃ for 120-480 min to obtain an off-white adsorbent;

[0048] Step seven: add the adsorbent obtained in step six into an industrial zinc sulfate solution according to a liquid-solid ratio of 2-10 g / L, and perform ultrasonic-assisted adsorption under stirring at 25-80℃, wherein the ultrasonic power is 360-900 W, the rotation speed is 80-180 r / min, and the stirring blade is at least one of Ag, Co, Mo, Pb, Zr, Al, C, Au, Cu, Si, W, Mg, Ni, Fe, Mn, Ti, or an alloy material comprising the above elements;

[0049] Step eight: after the defluorination of the adsorbent in step seven, perform filtration, washing, and drying, and then perform heat regeneration treatment at a calcination temperature of 350-550℃ and a calcination time of 120-480 min to obtain a regenerated adsorbent, which can be recycled for use in step seven.

[0050] As a preferred solution, the water-soluble aluminum salt in step one is at least one of aluminum sulfate, aluminum nitrate, and aluminum chloride, and the water-soluble zinc salt is at least one of zinc sulfate, zinc nitrate, zinc chloride, and zinc acetate; the water-soluble aluminum salt and the water-soluble zinc salt are dissolved in 50-150 mL of deionized water according to a molar ratio of [Al 3+ ]:[Zn 2+ ] 1:0.30-1.40.

[0051] As a preferred solution, the precipitant in step two is dissolved in 50-150 mL of deionized water according to a molar ratio of precipitant:[Al 3+ +Zn 2+ ] 6-38:1, and a transparent solution obtained after sufficient stirring is recorded as solution B; wherein the precipitant is composed of precipitant A and precipitant B according to a molar ratio of 0-5:1.5-3.5, precipitant A comprises at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonia water, ammonium carbonate, and ammonium bicarbonate, and precipitant B comprises at least one of urea and oxalic acid.

[0052] The precipitator A used in the present application is an inorganic compound, and its aqueous solution is mainly alkaline, which creates a suitable pH environment for the formation of the precursor of the adsorbent, and the precipitator B is an organic compound, and its aqueous solution is neutral or acidic, which provides a large amount of precipitated precursor (CO 2 3 - , C2O 2 4 - ) to create a suitable chemical environment for the final formation of the adsorbent precursor.

[0053] As a preferred solution, the mixed solution C obtained in step three is transferred to a high-pressure reaction kettle with a polytetrafluoroethylene liner in step four, and is reacted at 130-170℃ for 500-1400min; the high-pressure reaction kettle used has a specification of 100-300mL, preferably 150-250mL.

[0054] In the present application, the hydrothermal time and temperature should be strictly controlled. If the hydrothermal time is too short and the temperature is too low, the yield of the adsorbent precursor will be too low; if the hydrothermal time is too long and the temperature is too high, although the yield of the adsorbent precursor will increase, the physicochemical properties will change, and it will not have good economic efficiency and production efficiency; at the same time, the specification of the high-pressure reaction kettle should also be kept in a reasonable range, and should match the volume of the mixed solution added, otherwise the hydrothermal reaction pressure will be too high or too low, which will also seriously affect the structure formation of the adsorbent precursor.

[0055] The washing times in step five are 3-6 times, and the washing medium is deionized water, and the drying temperature is 80-100℃.

[0056] The calcination reaction atmosphere in step six is any atmosphere.

[0057] As a preferred solution, the precursor obtained in step six is calcined at 370-530℃ for 150-450min to generate a grayish white adsorbent.

[0058] The ultrasonic-assisted stirring adsorption reaction time in step seven is 30-120min; as a preferred solution, the reaction time is 40-110min, and the adsorbent is added to the industrial zinc sulfate solution according to a liquid-solid ratio of 3-9g / L, and is subjected to ultrasonic-assisted stirring adsorption at 30-70℃, wherein the ultrasonic power is 380-880W, the rotation speed is 90-170r / min, and the stirring blade is at least one of Ag, Co, Mo, Pb, Zr, Al, C, Au, Cu, Si, W, Mg, Ni, Fe, Mn, Ti or an alloy material including the above elements.

[0059] In the present application, the adsorption is carried out by using the method of "ultrasonic + stirring", and the stirring blade is specifically made of metal or non-metal whose work function is less than that of aluminum and zinc elements. The ultrasonic wave aims to create a certain number of oxygen vacancies and strengthen the adsorption process, greatly shortening the adsorption time. The material of the stirring blade aims to create the loss of the surface electrons of the adsorbent, so as to increase the number of positive charges on the surface of the adsorbent, improve the Zeta potential of the material, further expand the adsorption active site and the electrostatic adsorption force of the fluorine ion, and realize the significant improvement of the defluorination rate and the reduction of the zinc loss rate. At the same time, the ultrasonic time should not be too short or too long. If the ultrasonic time is too short, the number of oxygen vacancies will be insufficient, resulting in extremely low adsorption capacity and low defluorination rate. If the ultrasonic time is too long, the material structure will be seriously damaged, the porosity of the adsorbent will be extremely reduced, and the adsorbed fluorine ions will be dispersed back into the zinc sulfate solution due to the ultrasonic wave, resulting in a serious decrease in the defluorination rate. Too high or too low ultrasonic power will also cause the same problems as the ultrasonic time.

[0060] As a preferred solution, the calcination temperature in step eight is 370-530 DEG C, and the calcination time is 150-450 min.

[0061] From the attached Figure 1 It can be seen that the Al2O3-ZnO microsphere adsorbent is a nanoflower secondary particle half-wrapped Al2O3 microsphere composed of primary ZnO nanosheets, the outside of which is composed of ZnO nanosheets, and the inside is Al2O3 microspheres.

[0062] Example 1

[0063] (1) Dissolve aluminum sulfate and zinc sulfate in 50 mL of deionized water according to the molar ratio of [Al 3+ ]:[Zn 2+ ] 1:0.75, and obtain a mixed transparent solution by fully stirring, which is marked as solution A;

[0064] (2) Dissolve the precipitant in 100 mL of deionized water according to the molar ratio of precipitant:[Al 3+ +Zn 2+ ] 10:1, and obtain a transparent solution by fully stirring, which is marked as solution B; wherein the precipitant is composed of precipitant A and precipitant B according to the molar ratio of 1:1, precipitant A is ammonia water, and precipitant B is urea.

[0065] (3) Mix solution A and solution B obtained in steps (1) and (2) at 25 DEG C, and then stir at 80 r / min for 30 min to obtain a mixed transparent solution, which is marked as solution C.

[0066] (4) Transfer the mixed solution C obtained in step (3) into a polytetrafluoroethylene-lined high-pressure reaction kettle, and react at 120 DEG C for 600 min.

[0067] (5) After the reaction, the precipitate in the reactor of step (4) was vacuum filtered and washed, and the white precipitate was dried and ground.

[0068] (6) The precursor obtained in step (5) was calcined at 350°C for 120 min to obtain a gray adsorbent.

[0069] (7) The adsorbent obtained in step (6) was added to a zinc sulfate solution with a fluorine content of 120.28 mg / L and a pH of 5.4 at a solid-liquid ratio of 5 g / L, and was subjected to ultrasonic-assisted stirring adsorption at 30°C for 45 min under the conditions of an ultrasonic power of 500 W, a rotation speed of 100 r / min, and an Al material stirring paddle blade. After the adsorption, the fluorine ion concentration of the solution was reduced to 46.72 mg / L, the adsorption capacity of the adsorbent was 14.71 mg / g, and the zinc loss rate was 0.56%.

[0070] (8) After the adsorption, the adsorbent after defluorination in step (7) was vacuum filtered and washed with deionized water for 3-5 times, and then was dried in a blast drying oven at 80°C. Subsequently, the adsorbent was calcined at 350°C for 120 min to obtain a regenerated adsorbent for defluorination.

[0071] Comparative Example 1

[0072] Compared with Example 1, the only difference is that the aluminum sulfate and zinc sulfate in step (1) are in a molar ratio of [Al 3+ ]:[Zn 2+ ] 1:2. Then, the obtained adsorbent is subjected to defluorination, and the fluorine ion concentration of the solution after adsorption is reduced to 76.96 mg / L, the adsorption capacity of the adsorbent is 8.66 mg / g, and the zinc loss rate is 0.64%.

[0073] Comparative Example 2

[0074] Compared with Example 1, the only difference is that the aluminum sulfate and zinc sulfate in step (1) are in a molar ratio of [Al 3+ ]:[Zn 2+ ] 1:0.2. Then, the obtained adsorbent is subjected to defluorination, and the fluorine ion concentration of the solution after adsorption is reduced to 49.01 mg / L, the adsorption capacity of the adsorbent is 14.25 mg / g, and the zinc loss rate is 2.83%.

[0075] Comparative Example 3

[0076] Compared with Example 1, the only difference is that the precipitant in step (2) is in a molar ratio of precipitant:[Al 3+ +Zn 2+ ] 3:1. Then, the obtained adsorbent is subjected to defluorination, and the fluorine ion concentration of the solution after adsorption is reduced to 89.22 mg / L, the adsorption capacity of the adsorbent is 6.21 mg / g, and the zinc loss rate is 3.24%.

[0077] Comparative Example 4

[0078] Comparative Example 4 is the same as Example 1 except that the precipitant in step (2) is precipitant A and precipitant B in a molar ratio of 2:0. Precipitant A is ammonia water. Then, the obtained adsorbent is defluorinated, and the concentration of fluoride ions in the solution after adsorption is reduced to 91.63 mg / L, the adsorption capacity of the adsorbent is 5.73 mg / g, and the zinc loss rate is 2.94%. 3+ +Zn 2+ Comparative Example 5 is the same as Example 1 except that the precipitant in step (2) is precipitant A and precipitant B in a molar ratio of 2:5. Precipitant B is urea. Then, the obtained adsorbent is defluorinated, and the concentration of fluoride ions in the solution after adsorption is reduced to 48.35 mg / L, the adsorption capacity of the adsorbent is 14.39 mg / g, and the zinc loss rate is 0.54%. However, the amount of precipitant B is increased.

[0079] Comparative Example 5

[0080] Comparative Example 5 is the same as Example 1 except that the precipitant in step (2) is precipitant A and precipitant B in a molar ratio of 2:5. Precipitant B is urea. Then, the obtained adsorbent is defluorinated, and the concentration of fluoride ions in the solution after adsorption is reduced to 48.35 mg / L, the adsorption capacity of the adsorbent is 14.39 mg / g, and the zinc loss rate is 0.54%. However, the amount of precipitant B is increased.

[0081] Comparative Example 6

[0082] Comparative Example 6 is the same as Example 1 except that the precipitant in step (2) is precipitant A and precipitant B in a molar ratio of 2:5. Precipitant B is urea. Then, the obtained adsorbent is defluorinated, and the concentration of fluoride ions in the solution after adsorption is reduced to 48.35 mg / L, the adsorption capacity of the adsorbent is 14.39 mg / g, and the zinc loss rate is 0.54%. However, the amount of precipitant B is increased.

[0083] Comparative Example 7

[0084] Comparative Example 7 is the same as Example 1 except that the polytetrafluoroethylene-lined high-pressure reactor in step (4) is reacted at 200°C for 600 min. Then, the obtained adsorbent is defluorinated, and the concentration of fluoride ions in the solution after adsorption is reduced to 73.36 mg / L, the adsorption capacity of the adsorbent is 9.38 mg / g, and the zinc loss rate is 0.66%.

[0085] Comparative Example 8

[0086] Comparative Example 8 is the same as Example 1 except that the polytetrafluoroethylene-lined high-pressure reactor in step (4) is reacted at 100°C for 600 min. Then, the obtained adsorbent is defluorinated, and the concentration of fluoride ions in the solution after adsorption is reduced to 93.36 mg / L, the adsorption capacity of the adsorbent is 5.38 mg / g, and the zinc loss rate is 3.22%.

[0087] Comparative Example 9

[0088] The difference between the example 1 and the comparative example 2 is that the precursor obtained in step (5) is calcined at 650°C for 120 min. Then, the obtained adsorbent is defluorinated, and the concentration of fluoride ion in the solution after adsorption is reduced to 78.75 mg / L, the adsorption capacity of the adsorbent is 8.31 mg / g, and the loss rate of zinc is 0.63%.

[0089] Comparative example 10

[0090] The difference between the example 1 and the comparative example 11 is that the precursor obtained in step (5) is not calcined. Then, the obtained adsorbent is defluorinated, and the concentration of fluoride ion in the solution after adsorption is reduced to 107.98 mg / L, the adsorption capacity of the adsorbent is 2.46 mg / g, and the loss rate of zinc is 4.25%.

[0091] Comparative example 11

[0092] The difference between the example 1 and the comparative example 11 is that the precursor obtained in step (5) is not calcined. Then, the obtained adsorbent is defluorinated, and the concentration of fluoride ion in the solution after adsorption is reduced to 107.98 mg / L, the adsorption capacity of the adsorbent is 2.46 mg / g, and the loss rate of zinc is 4.25%.

[0093] Comparative example 12

[0094] The difference between the example 1 and the comparative example 12 is that the adsorbent obtained in step (6) is added into the industrial zinc sulfate solution with a fluorine content of 120 mg / L and a pH of 5.4 at a solid-liquid ratio of 5 g / L, and the adsorption is carried out by ordinary stirring at 30°C for 45 min at a rotating speed of 100 r / min, and the stirring paddle blade is made of Al. After adsorption, the concentration of fluoride ion in the solution is reduced to 76.26 mg / L, the adsorption capacity of the adsorbent is 8.80 mg / g, and the loss rate of zinc is 0.63%.

[0095] Comparative example 13

[0096] The difference between the example 1 and the comparative example 13 is that the adsorbent obtained in step (6) is added into the industrial zinc sulfate solution with a fluorine content of 120 mg / L and a pH of 5.4 at a solid-liquid ratio of 5 g / L, and the adsorption is carried out by ultrasonic-assisted stirring at 30°C for 45 min at a rotating speed of 100 r / min, and the stirring paddle blade is made of ordinary PVC plastic. After adsorption, the concentration of fluoride ion in the solution is reduced to 79.29 mg / L, the adsorption capacity of the adsorbent is 8.20 mg / g, and the loss rate of zinc is 0.67%.

[0097] Comparative example 14

[0098] Compared with Example 1, the difference is that the adsorbent obtained in step (6) is added into the industrial zinc sulfate solution with a fluorine content of 120 mg / L and a pH of 5.4 at a solid-liquid ratio of 5 g / L, and ultrasonic-assisted stirring adsorption is carried out at 30°C for 10 min at a rotating speed of 100 r / min with the stirring blade made of Al. After adsorption, the fluorine ion concentration of the solution is reduced to 96.35 mg / L, the adsorption capacity of the adsorbent is 4.79 mg / g, and the zinc loss rate is 0.34%.

[0099] Comparative Example 15

[0100] Compared with Example 1, the difference is that the adsorbent obtained in step (6) is added into the industrial zinc sulfate solution with a fluorine content of 120 mg / L and a pH of 5.4 at a solid-liquid ratio of 5 g / L, and ultrasonic-assisted stirring adsorption is carried out at 30°C for 150 min at a rotating speed of 100 r / min with the stirring blade made of Al. After adsorption, the fluorine ion concentration of the solution is reduced to 48.35 mg / L, the adsorption capacity of the adsorbent is 14.39 mg / g, and the zinc loss rate is 4.12%.

[0101] Comparative Example 16

[0102] Compared with Example 1, the difference is that the adsorbent obtained in step (6) is added into the industrial zinc sulfate solution with a fluorine content of 120 mg / L and a pH of 5.4 at a solid-liquid ratio of 1 g / L, and ultrasonic-assisted stirring adsorption is carried out at 30°C for 45 min at a rotating speed of 100 r / min with the stirring blade made of Al. After adsorption, the fluorine ion concentration of the solution is reduced to 102.35 mg / L, the adsorption capacity of the adsorbent is 17.93 mg / g, and the zinc loss rate is 0.38%. Although the adsorption capacity is better under the condition of lower adsorbent dosage, the fluorine ion concentration in the solution under the condition of lower adsorbent dosage is difficult to meet the requirements of industrial application.

[0103] It can be found through the comparison of the examples and comparative examples that only within the scope of the present application can the fluorine ion concentration in the zinc sulfate solution meet the requirements of industrial application under the condition of appropriate adsorbent dosage, and the adsorbent exhibits higher adsorption capacity and lower zinc loss.

[0104] Example 2

[0105] (1) Aluminum nitrate and zinc nitrate are dissolved in 100 mL of deionized water at a molar ratio of [Al 3+ ]:[Zn 2+ ] 1:1 to obtain a mixed transparent solution, which is denoted as solution A;

[0106] (2) The precipitant is added into the solution A at a precipitant:[Al 3+ +Zn 2+]mole ratio 20:1 was dissolved in 100 mL of deionized water, and a transparent solution obtained by sufficient stirring was recorded as solution B; wherein, the precipitant was composed of precipitant A and precipitant B according to a mole ratio of 1:2, the precipitant A was ammonium carbonate, and the precipitant B was urea.

[0107] (3) The solution A and solution B obtained in steps (1) and (2) were mixed at 35℃, and then stirred at 100 r / min for 90 min to obtain a mixed transparent solution, which was recorded as solution C.

[0108] (4) The mixed solution C obtained in step (3) was transferred into a high-pressure reaction kettle with a polytetrafluoroethylene liner, and reacted at 140℃ for 720 min.

[0109] (5) After the reaction was completed, the precipitate in the reaction kettle of step (4) was vacuum filtered and washed, and the white precipitate was dried and ground.

[0110] (6) The precursor obtained in step (5) was calcined at 450℃ for 150 min to generate a grayish white adsorbent.

[0111] (7) The adsorbent obtained in step (6) was added into an industrial zinc sulfate solution with a fluorine content of 120.28 mg / L and a pH of 5.4 according to a solid-liquid ratio of 7 g / L, and was subjected to ultrasonic-assisted stirring adsorption under the conditions of 40℃, 60 min, an ultrasonic power of 450 W, a rotating speed of 120 r / min, and a stirring blade made of Fe material. After the adsorption, the fluorine ion concentration of the solution was reduced to 32.74 mg / L, the adsorption capacity of the adsorbent was 12.51 mg / g, and the zinc loss rate was 0.51%.

[0112] (8) After the adsorption was completed, the defluorinated adsorbent after step (7) was vacuum filtered and washed with deionized water for 3-5 times, and then was placed in a blast drying oven for drying at 80℃. Subsequently, the adsorbent was calcined at 450℃ for 150 min for regeneration to obtain a regenerated adsorbent for defluorination.

[0113] Example 3

[0114] (1) Aluminum chloride and zinc chloride were dissolved in 150 mL of deionized water according to a mole ratio of [Al 3+ ]:[Zn 2+ ] 1:1.25, and a mixed transparent solution obtained by sufficient stirring was recorded as solution A;

[0115] (2) A precipitant was dissolved in 150 mL of deionized water according to a mole ratio of precipitant:[Al 3+ + Zn 2+ ] 15:1, and a transparent solution obtained by sufficient stirring was recorded as solution B; wherein, the precipitant was composed of precipitant A and precipitant B according to a mole ratio of 3:4, the precipitant A was ammonium carbonate, and the precipitant B was oxalic acid.

[0116] (3) The solution A and solution B obtained in step (1) and step (2) were mixed at 50℃ and stirred at 120 r / min for 150 min to obtain a mixed transparent solution, which was marked as solution C.

[0117] (4) The mixed solution C obtained in step (3) was transferred into a high-pressure reactor with a polytetrafluoroethylene liner and reacted at 140℃ for 840 min.

[0118] (5) After the reaction was completed, the precipitate in the reactor of step (4) was vacuum filtered and washed, and the white precipitate was dried and ground.

[0119] (6) The precursor obtained in step (5) was calcined at 550℃ for 180 min to obtain a grayish white adsorbent.

[0120] (7) The adsorbent obtained in step (6) was added to an industrial zinc sulfate solution with a fluorine content of 120.28 mg / L and a pH of 5.4 at a solid-liquid ratio of 5 g / L, and ultrasonic-assisted stirring adsorption was carried out at 35℃ for 30 min, with an ultrasonic power of 650 W, a rotation speed of 150 r / min, and an Ag material stirring paddle blade. After adsorption, the fluorine ion concentration of the solution was reduced to 44.69 mg / L, the adsorption capacity of the adsorbent was 15.12 mg / g, and the zinc loss rate was 0.55%.

[0121] (8) After the adsorption was completed, the defluorinated adsorbent of step (7) was vacuum filtered and washed with deionized water for 3-5 times, and then dried in a blast drying oven at 80℃. Subsequently, the regenerated adsorbent was obtained by calcining at 550℃ for 180 min.

[0122] The above is only the result of the preferred embodiment of the present application.

Claims

1. An Al2O3-ZnO microsphere adsorbent for defluorination of zinc sulfate solution, characterized in that, Al2O3-ZnO microsphere adsorbent is composed of nanoflower-like secondary particles made up of primary ZnO nanosheets that partially encapsulate Al2O3 microspheres. The outer layer is composed of ZnO nanosheets, and the inner layer is composed of Al2O3 microspheres. The Al2O3-ZnO microsphere adsorbent comprises the following two components by mass percentage: 1) The mass ratio of alumina to zinc oxide is 34.64-44.12% : 55.88-65.36%; 2) Adsorbent specific surface area (S) BET ) is 52-301m 2 / g, pore size distribution of 7.7-18.5nm, porosity of 0.14-0.39cm 3 / g, with a particle size of 1-60μm, and morphological characteristics of nanoflower secondary particles composed of primary ZnO nanosheets semi-encapsulated Al2O3 microspheres, with an oxygen vacancy content of 0.2-5%.

2. The method for preparing an Al2O3-ZnO microsphere adsorbent for defluorination of zinc sulfate solution according to claim 1, characterized in that, Includes the following steps: Step 1: Mix water-soluble aluminum salt and water-soluble zinc salt according to [Al 3+ ]:[Zn 2+ The mixed transparent solution obtained by dissolving the molecules in deionized water at a molar ratio and stirring thoroughly is denoted as solution A; Step 2: Add the precipitant according to the precipitant ratio: [Al] 3+ +Zn 2+ The molar ratio of the solution to the solution is dissolved in deionized water, and the resulting transparent solution is denoted as solution B. Step 3: Mix solution A and solution B obtained in Step 1 and Step 2 and stir to obtain a mixed transparent solution, which is denoted as solution C; Step 4: Transfer the mixed solution C obtained in Step 3 to a high-pressure reactor lined with polytetrafluoroethylene for reaction; Step 5: After the reaction in Step 4 is completed, the precipitate in the reaction vessel of Step 4 is vacuum filtered and washed. The white precipitate is dried and ground to obtain the precursor. Step 6: The precursor obtained in Step 5 is calcined under certain conditions to generate a grayish-white adsorbent; Step 7: Add the adsorbent obtained in Step 6 to an industrial zinc sulfate solution, and perform ultrasonic-assisted adsorption using a stirring paddle under certain conditions; Step 8: After the adsorbent in Step 7 has been defluorinated, filtered, washed and dried, it is then subjected to thermal regeneration to obtain a regenerated adsorbent. The regenerated adsorbent can be recycled by repeating the operation in Step 7.

3. The method for preparing an Al2O3-ZnO microsphere adsorbent for defluorination of zinc sulfate solution according to claim 2, characterized in that, The water-soluble aluminum salt mentioned in step one is at least one of aluminum sulfate, aluminum nitrate, and aluminum chloride, and the water-soluble zinc salt is at least one of zinc sulfate, zinc nitrate, zinc chloride, and zinc acetate. Water-soluble aluminum salts and water-soluble zinc salts are arranged according to [Al 3+ ]:[Zn 2+ Dissolve in deionized water at a molar ratio of 1:0.25-1.

5.

4. The method for preparing an Al2O3-ZnO microsphere adsorbent for defluorination of zinc sulfate solution according to claim 2, characterized in that, In step two, the precipitant is precipitated as follows: [Al] 3+ +Zn 2+ The solution obtained by dissolving in deionized water at a molar ratio of 5-40:1 and stirring thoroughly is denoted as solution B; wherein, the precipitant is composed of precipitant A and precipitant B at a molar ratio of 0-6:1-4, precipitant A includes at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonia, ammonium carbonate, and ammonium bicarbonate, and precipitant B includes at least one of urea and oxalic acid.

5. The method for preparing an Al2O3-ZnO microsphere adsorbent for defluorination of zinc sulfate solution according to claim 2, characterized in that, In step three, after mixing at 25-65℃, stir at 80-150r / min for 30-180min.

6. The method for preparing an Al2O3-ZnO microsphere adsorbent for defluorination of zinc sulfate solution according to claim 2, characterized in that, In step four, the mixed solution C obtained in step three is transferred to a high-pressure reactor lined with polytetrafluoroethylene and reacted at 120-180℃ for 480-1440 min; the high-pressure reactor used has a capacity of 100-300 mL. In step five, the washing is performed 3-6 times, the washing medium is deionized water, and the drying temperature is 80-100℃.

7. The method for preparing an Al2O3-ZnO microsphere adsorbent for defluorination of zinc sulfate solution according to claim 2, characterized in that, In step six, the calcination reaction atmosphere can be any atmosphere, and the calcination is carried out at 350-550℃ for 120-480 minutes.

8. The method for preparing an Al2O3-ZnO microsphere adsorbent for defluorination of zinc sulfate solution according to claim 2, characterized in that, The adsorbent obtained in step six is ​​added to an industrial zinc sulfate solution at a liquid-to-solid ratio of 2-10 g / L. The adsorption is carried out under ultrasonic-assisted stirring with a stirring paddle at 25-80℃, wherein the ultrasonic power is 360-900W and the rotation speed is 80-180 r / min. The ultrasonic-assisted stirring adsorption reaction time in step seven is 30-120 min. The stirring paddle blades are at least one of Ag, Co, Mo, Pb, Zr, Al, C, Au, Cu, Si, W, Mg, Ni, Fe, Mn, Ti or an alloy material including the above elements.

9. The method for preparing an Al2O3-ZnO microsphere adsorbent for defluorination of zinc sulfate solution according to claim 2, characterized in that, In step eight, the calcination temperature for the thermal regeneration treatment is 350-550℃, and the calcination time is 120-480 min.

10. The application of the adsorbent according to any one of claims 1-9, characterized in that, The adsorbent is applied to zinc sulfate solutions and other similar fluorine-containing solutions.

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