A preparation method and application of modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater

Abstract

The present invention discloses a modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater, and a preparation method and application thereof, and relates to the technical field of comprehensive utilization of phosphate tailings resources. The preparation method comprises: (1) mixing and grinding reverse flotation phosphate tailings, forward flotation phosphate tailings, and montmorillonite to obtain a mixture; (2) granulating the mixture to obtain raw material balls, and drying to obtain dried raw material balls; (3) placing the dried raw material balls in a muffle furnace for roasting to obtain primary tailings ceramsite; (4) placing the primary tailings ceramsite in deionized water, and adding a rare earth modification solution with a pH of 4 to 5 dropwise under stirring in a constant temperature water bath at 30 to 60° C.; after the addition is completed, stirring is continued in a constant temperature water bath for 2 to 6 hours, and then the solution is allowed to stand in a constant temperature water bath for aging for 8 to 10 hours, and then taken out and dried to obtain the modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater. The present invention has the advantages of low cost, short production cycle, good phosphorus removal effect, and the like. The obtained high-efficiency phosphorus removal ceramsite has a strong adsorption effect on phosphate.

Description

Technical Field

[0001] The invention relates to the technical field of comprehensive utilization of phosphorus tailings resources, and in particular to a preparation method of modified phosphorus tailings ceramsite for deep treatment of phosphorus-containing wastewater and application thereof. Background Art

[0002] Phosphate tailings are a byproduct produced during the mining and enrichment of phosphate rock. Based on the beneficiation process, they can be divided into direct flotation tailings and reverse flotation tailings. Direct flotation tailings primarily consist of quartz and silicate minerals, while reverse flotation tailings primarily consist of calcite and dolomite. These are silicon-rich and calcium-magnesium-rich secondary solid waste resources, respectively. Phosphate tailings require significant land resources for storage, and the annual maintenance of tailings ponds consumes significant financial and material resources. Some chemical elements in the tailings undergo chemical migration during storage, potentially contaminating the surrounding soil and damaging surrounding vegetation.

[0003] The main wastewater type in the phosphorus chemical industry is phosphorus-containing wastewater, with a total phosphorus concentration of 50-1000 mg·L -1 About, which is a high-concentration phosphorus-containing wastewater. The traditional treatment method is chemical precipitation, which adds chemical agents (such as calcium salts, iron salts, aluminum salts, etc.) to the wastewater to make the phosphates in the wastewater react with the metal cations in the agents to form insoluble phosphate precipitates. This method will produce a large amount of bottom sludge. It is not only difficult to separate these precipitates from the wastewater by filtration, precipitation or solid-liquid separation, but also requires proper management of waste residues to avoid secondary pollution; the biological treatment method is to use the biochemical action of polyphosphate bacteria to degrade phosphorus in the water body, but it is not applicable because the total phosphorus concentration in the wastewater is too high, and pretreatment and deep treatment are required, which increases the cost of treatment. Relevant researchers have prepared some functional ceramsite as water treatment materials for phosphorus-containing wastewater, but the phosphorus removal ceramsite is difficult to achieve deep removal of phosphorus-containing wastewater (0.5mg·L -1 Below), and in the production process of phosphorus chemical industry, a large amount of H + PO4 3- 、SO4 2- 、F - Impurity ions such as phosphorus and phosphorus oxides will enter the wastewater, making the phosphorus chemical wastewater highly acidic, with high total phosphorus concentration and impurity ions, which are difficult to treat.

[0004] If phosphate tailings could be used to treat phosphorus-containing wastewater, it would not only reduce wastewater treatment costs in the phosphorus chemical industry but also allow for large-scale disposal of phosphate tailings, promoting the sustainable development of China's phosphorus chemical industry. Therefore, it is necessary to develop a method for using phosphate tailings to prepare functional ceramsite for deep treatment of phosphorus-containing wastewater. The resulting modified ceramsite has a wide treatment concentration range, high reaction efficiency, and strong anti-interference properties. Summary of the Invention

[0005] The purpose of the present invention is to solve the shortcomings of the above-mentioned background technology. With direct flotation phosphate tailings and reverse flotation phosphate tailings as the main base material and montmorillonite as an auxiliary agent, a preparation method of modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater is provided. The prepared modified phosphate tailings ceramsite has a wide treatment concentration range, high reaction efficiency and strong anti-interference ability.

[0006] The technical solution of the present invention is: a method for preparing modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater, comprising the following steps:

[0007] (1) mixing and grinding the forward flotation phosphate tailings, the reverse flotation phosphate tailings, and montmorillonite to obtain a mixed powder;

[0008] (2) granulating the mixed powder to obtain raw material balls, and drying to obtain dry raw material balls;

[0009] (3) placing the dried raw material balls in a muffle furnace for roasting to obtain primary tailings ceramsite;

[0010] (4) placing the original tailings ceramsite in deionized water, adding a rare earth modified solution with a pH of 4 to 5 under stirring in a constant temperature water bath at 30 to 60° C., wherein the rare earth modified solution contains trivalent rare earth ions RE with a concentration of 0.01 to 0.05 mol / L. 3+ , RE is lanthanum and / or cerium;

[0011] After the dropwise addition is completed, the original temperature is maintained and the mixture is stirred in a constant temperature water bath for 2 to 6 hours, and then the original temperature is maintained and the mixture is allowed to stand and age for 8 to 10 hours. The mixture is taken out and dried to obtain modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater.

[0012] Preferably, in step (1), the mixed powder contains 35-45% of forward flotation phosphate tailings, 35-45% of reverse flotation phosphate tailings, and 15-20% of montmorillonite by mass percentage, and the sum of the mass percentages of the above components is 100%.

[0013] Preferably, in step (2), H2O2 solution with a mass concentration of 5-10% is sprayed into the granulation process, wherein the mass ratio of H2O2 solution: mixed powder = (2-5):100.

[0014] Preferably, in step (2), granulation is performed to obtain raw balls with a particle size of 4-6 mm, which are then placed in an oven at 100-110° C. and dried for 2-3 hours to obtain dried raw balls.

[0015] Preferably, in step (3), the calcination comprises: firstly calcining at 8-10°C·min -1 Heat to 350-450℃ and preheat for 30-60min, then heat at 5-10℃·min -1The temperature is raised to 950-1050°C at a constant rate for 60-120 minutes, cooled to below 300°C along with the furnace, taken out, and cooled to room temperature to obtain primary tailings ceramsite.

[0016] Preferably, in step (4), the rare earth modified solution is obtained by adjusting the pH of an aqueous solution of rare earth nitrate RE(NO3)3 by nitric acid HNO3 to 4-5, or by adjusting the pH of an aqueous solution of rare earth chloride RECl3 by hydrochloric acid HCl to 4-5;

[0017] The dosage ratio of the original tailings ceramsite, deionized water and rare earth modified solution is 1g: 2-5mL: 5-10m, and the rare earth modified solution is added dropwise for 2-3h.

[0018] Preferably, in step (4), after taking out, the mixture is dried in an oven at 100-110° C. for 2-3 hours.

[0019] Preferably, in step (4), the mass concentration of nitric acid or hydrochloric acid used for adjusting the pH does not exceed 10%, the stirring speed during the constant temperature water bath is 10 to 30 r / min, and the temperature remains consistent throughout the entire constant temperature water bath process.

[0020] Among the raw materials used in the present invention:

[0021] The SiO2 content in the direct flotation phosphate tailings ranges from 26 to 38%, the Al2O3 content ranges from 3 to 6%, the CaO+MgO content ranges from 24 to 28%, and the rest are impurities;

[0022] The SiO2 content in reverse flotation phosphate tailings ranges from 4 to 10%, the CaO+MgO content ranges from 44 to 62%, and the rest is impurities;

[0023] The SiO2 content in montmorillonite ranges from 40% to 66%, the Al2O3 content ranges from 20% to 25%, and the remainder is MgO+CaO and impurities (the above percentages are all mass percentages).

[0024] The present invention also provides a modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater, which is prepared by any of the above methods for preparing modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater.

[0025] The present invention also provides an application of modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater, which is used for deep treatment of total phosphorus concentration of 10 mg·L -1 ~1000mg·L -1 , rich in SO4 2- and F - Phosphorus chemical wastewater containing impurity ions.

[0026] Preferably, the dosage of the modified phosphate tailings ceramsite is 10 g·L -1 ~120g·L-1 .

[0027] Preferably, F in phosphorus chemical wastewater - Concentration not exceeding 150 mg·L -1 、SO4 2- Concentration not exceeding 250 mg·L -1 .

[0028] In the above preparation method:

[0029] (1) In the present invention, the SiO2 content of the positive flotation phosphate tailings is above 26%, and the SiO2 content of montmorillonite is above 40%. The two mainly serve as silicon sources for the tailings ceramsite; the Al2O3 content of montmorillonite is above 20%, which mainly serves as an aluminum source for the tailings ceramsite. During the high-temperature roasting process, quartz and montmorillonite in the positive flotation phosphate tailings will generate mullite crystal phase as the tailings ceramsite skeleton, which can effectively enhance the compressive strength and acid resistance of the ceramsite.

[0030] (2) The CaO+MgO content of the reverse flotation phosphate tailings in the present invention is above 44%, which mainly serves as the reactive substrate of the tailings ceramsite. During the high-temperature roasting process, the dolomite in the reverse flotation phosphate tailings undergoes thermal decomposition to generate a large amount of CaO, MgO and CO2. CaO and MgO have a highly efficient reaction binding ability with phosphate in the water body. The escape of CO2 can also form a rich pore structure, which is conducive to providing more reaction space.

[0031] (3) The rare earth modified solution in the present invention is any one of RE(NO3)3+HNO3 and RECl3+HCl solutions with a weak acidic pH of 4 to 5, wherein RE is lanthanum La and / or cerium Ce. The modification principle is based on the acid-base proton theory: the surface of the primary tailings ceramsite is rich in CaO and MgO components, and it will release Ca when immersed in water. 2+ Mg 2+ and OH - By adding a weakly acidic rare earth modified solution, H + It will quickly neutralize OH in the water phase - , will promote La 3+ or Ce 3+ Loaded on the surface of tailings ceramsite, on the one hand, it ensures the La 3+ or Ce 3+ Will not react with OH in the water phase - The precipitation is lost; on the other hand, La 3+ or Ce 3+ The load further blocks the Ca 2+ Mg 2+ The release of Ca in tailings ceramsite is effectively inhibited 2+ Mg 2+ of hydrolysis loss.

[0032] (4) The surface of the modified phosphate tailings ceramsite in the present invention is covered with a large amount of rare earth ions to solidify the Ca 2+ , so that the Ca released from the water 2+ The content is very small, which avoids the formation of CaSO4 and covers the adsorption sites on the surface of the ceramsite to make the ceramsite passivated, thus avoiding SO4 2- On the other hand, the surface is covered with a large number of rare earth ions and the solubility product of phosphate is smaller than the solubility product of rare earth ions and fluoride ions, so it reacts with phosphate first, thus avoiding F - interference.

[0033] The present invention has the following beneficial effects:

[0034] (1) The present invention provides a resource utilization method for industrial solid waste, which uses the solid waste of the phosphorus chemical industry - direct flotation and reverse flotation phosphate tailings as the main substrate, and montmorillonite as a binder. The modified phosphate tailings ceramsite is prepared through a series of processes such as granulation, roasting, and modification. The modified ceramsite has a rich mesoporous structure and has good adsorption performance; the reaction efficiency is high, the reaction activity is strong, and it is suitable for 10 to 1000 mg·L -1 Deep treatment of phosphorus-containing wastewater; compressive strength above 2.0Mpa, and conducive to recycling and reuse.

[0035] (2) The reverse flotation phosphate tailings in the present invention are rich in dolomite, which undergoes thermal decomposition during high-temperature calcination, releasing a large amount of CO2 and forming a rich pore structure. In addition to providing more adsorption reaction space, the product CaO and MgO also serve as fluxes for quartz and montmorillonite in the forward flotation phosphate tailings, further promoting the formation of the tailings ceramsite skeleton structure.

[0036] (3) The modification method of tailings ceramsite of the present invention is a new attempt based on the acid-base proton balance theory. The CaO and MgO components rich in the surface of the original tailings ceramsite are not inert phases, and will release a large amount of Ca when immersed in water. 2+ and Mg 2+ , directly put into phosphorus-containing wastewater for use, a large amount of flocculent precipitates will be generated in the aqueous phase, affecting the turbidity and hardness of the water body. When the tailings ceramsite modified by the proton balance method is used to treat actual phosphorus-containing wastewater, since the lanthanum (cerium) ions cover the surface of the tailings ceramsite, they first react with the phosphate in the wastewater to form lanthanum (cerium) phosphate, which effectively avoids the release of calcium ions on the surface of the tailings ceramsite and combines with the phosphate and sulfate in the solution to form flocculent precipitates, which leads to increased turbidity of the wastewater; at the same time, the modified phosphorus tailings ceramsite and phosphate are chelated in the pores of the tailings ceramsite in the form of lanthanum (cerium) phosphate precipitation, which does not affect the adsorption of phosphate into the interior of the tailings ceramsite to form calcium phosphate, thereby further achieving the purpose of phosphorus removal.

[0037] (4) The modified phosphate tailings ceramsite provided by the present invention has an effect on the coexisting ions F in phosphorus chemical wastewater - 、SO4 2- Has strong anti-interference ability. SO4 2- The interference is that it will interact with Ca in the solution 2+ The modified phosphate tailings ceramsite of the present invention releases Ca2+ in the solution. 2+ The content is very small, which avoids the formation of CaSO4 and covers the adsorption sites on the surface of the ceramsite, causing the ceramsite to become passivated. On the other hand, F - The interference is that it has a very strong electronegativity. Since the phosphorus tailings ceramsite of the present invention is modified by lanthanum (cerium), its surface is covered with a large number of lanthanum (cerium) ions, and the solubility product of lanthanum (cerium) phosphate is smaller than that of lanthanum (cerium) fluoride. 3+ (Ce 3+ ) will preferentially chelate with phosphate, thereby - The interference is greatly reduced.

[0038] (5) The modified phosphate tailings ceramsite of the present invention is suitable for pH = 2 to 12 and impurity fluorine concentration ≤ 150 mg·L -1 , total phosphorus concentration 10~1000mg·L -1 The dosage of modified phosphate tailings ceramsite is 20g·L -1 After 2 to 4 hours of reaction, the total phosphorus concentration in the wastewater can be reduced to 0.5 mg·L -1 Below, the removal efficiency can reach more than 99.8%, and the deep treatment effect is significant.

[0039] (6) The modified phosphate tailings ceramsite preparation process of the present invention is simple and safe, and is suitable for industrial-scale production. Furthermore, since most of the raw materials of the present invention are solid wastes such as tailings, it can also achieve the win-win goal of "using waste to treat waste." BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The X-ray diffraction pattern (XRD) of PTC-01 prepared in Example 1;

[0041] Figure 2 N2 adsorption-desorption curve and pore size distribution (BET) of PTC-01 prepared in Example 1;

[0042] Figure 3 The scanning electron microscope (SEM) and energy spectrum scanning diagram (mapping) of PTC-01 prepared in Example 1 before and after adsorption;

[0043] Figure 4Actual photos of PTC-01, PTC-02, PTC-03 prepared in Examples 1 to 3 and DPC-01 and DPC-02 prepared in Comparative Examples 1 to 2 treating simulated phosphorus-containing wastewater;

[0044] Figure 5 This is a data graph showing the treatment of simulated phosphorus-containing wastewater by PTC-01, PTC-02, PTC-03, and DPC-01, DPC-02 in Example 5;

[0045] Figure 6 This is a data chart showing the treatment of actual phosphorus chemical wastewater by PTC-02, PTC-03, PTC-04, DPC-01, and DPC-02 in Example 6;

[0046] Figure 7 This is a data chart showing the treatment of actual phosphorus chemical wastewater by PTC-02, PTC-03, PTC-04, DPC-01, and DPC-02 in Example 7;

[0047] Figure 8 These are actual pictures of the products of Examples 1 to 4. DETAILED DESCRIPTION

[0048] The following specific examples further illustrate the present invention. The drugs used in the examples are all commercially available unless otherwise specified, and the methods used are all conventional methods in the art unless otherwise specified. The amounts of raw materials used in Examples 1-4 and Comparative Examples 1-2 are shown in Table 1.

[0049] Table 1 Granulation raw material dosage

[0050]

[0051] The SiO2 content in the direct flotation phosphate tailings is 36.83%, and the average particle size is ≤38μm.

[0052] The content of CaO+MgO in the reverse flotation phosphate tailings is 55.45%, and the average particle size is ≤38μm.

[0053] The SiO2 content in montmorillonite is 58.95%, the Al2O3 content is 20.06%, and the average particle size is ≤38μm.

[0054] Example 1

[0055] This embodiment provides a method for preparing modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater, and the steps are as follows:

[0056] (1) Weigh 4 g of direct flotation phosphate tailings, 4 g of reverse flotation phosphate tailings, and 2 g of montmorillonite, mix them evenly, and grind them into 200 mesh (screening rate of more than 80%) using a dry grinder to obtain a mixed powder;

[0057] (2) The mixed powder is placed in a granulator for granulation. During the granulation process, a 5% H2O2 solution is sprayed in, wherein the mass ratio of H2O2 solution to mixed powder is 2:100. After granulation, a round-hole sieve is used to screen out raw material balls with a particle size of 4-6 mm. The balls are placed in an oven at 105°C and dried for 2 hours to obtain dry raw material balls.

[0058] (3) Place the dried raw material balls into a muffle furnace for roasting. The roasting process is as follows: adjust the heating rate to 8°C·min -1 Heat to 450℃ and preheat for 30min, then 5℃·min -1 The temperature was raised to 950°C and kept constant for 60 minutes, then the product was cooled to below 300°C and taken out of the furnace, and cooled to room temperature to obtain the original tailings ceramsite.

[0059] (4) Prepare rare earth modified solution: at a concentration of 0.05 mol·L -1 To the La(NO3)3 solution, add a 10% HNO3 solution to adjust the pH to 4-5 to obtain a rare earth modified solution (RE in this embodiment is lanthanum);

[0060] The original tailings ceramsite was placed in deionized water, and the rare earth modified solution was slowly added dropwise under stirring conditions in a constant temperature water bath of 30-60°C (specifically, the temperature was 30°C and the stirring rate was 30r / min). The addition time was 2h, and the dosage ratio of the original tailings ceramsite, deionized water, and rare earth modified solution was 1g:2mL:5mL. After the addition was completed, the entire system was stirred in a constant temperature water bath for 4h, kept at the original temperature in the constant temperature water bath for aging for 8h, and dried in an oven at 105°C for 2h to obtain modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater, which was named PTC-01.

[0061] Example 2

[0062] This embodiment provides a method for preparing modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater, and the steps are as follows:

[0063] (1) Weigh 4.5 g of direct flotation phosphate tailings, 3.5 g of reverse flotation phosphate tailings, and 2 g of montmorillonite, mix them evenly, and grind them into 200 mesh (screening rate 80%) using a dry grinder to obtain a mixed powder;

[0064] (2) The mixed powder is placed in a granulator for granulation. During the granulation process, a 5% H2O2 solution is sprayed in, wherein the mass ratio of H2O2 solution to mixed powder is 2:100. After granulation, a round-hole sieve is used to screen out raw material balls with a particle size of 4-6 mm. The balls are placed in an oven at 105°C and dried for 2 hours to obtain dry raw material balls.

[0065] (3) Place the dried raw material balls into a muffle furnace for roasting. The roasting process is as follows: adjust the heating rate to 8°C·min -1Heat to 450℃ and preheat for 30min, then heat at 5℃·min -1 The temperature is raised to 950°C and kept constant for 60 minutes, then the product is cooled to below 300°C and taken out of the furnace, and cooled to room temperature to obtain the original tailings ceramsite.

[0066] (4) Prepare rare earth modified solution: at a concentration of 0.01 mol·L -1 To the La(NO3)3 solution, add a 10% HNO3 solution to adjust the pH to 4-5 to obtain a rare earth modified solution (RE in this embodiment is lanthanum);

[0067] The original tailings ceramsite was placed in deionized water, and the rare earth modified solution was slowly added dropwise at 30-60°C (constant temperature water bath stirring conditions (specifically, the temperature was 30°C and the stirring rate was 30r / min). The addition time was 2h, and the amount ratio of the original tailings ceramsite, deionized water, and rare earth modified solution was 1g:5mL:5mL. After the addition was completed, the whole system was stirred in a constant temperature water bath for 4h, kept at the original temperature in the constant temperature water bath for aging for 8h, and dried in an oven at 105°C for 2h to obtain modified phosphorus tailings ceramsite for deep treatment of phosphorus-containing wastewater, named PTC-02.

[0068] Example 3

[0069] This embodiment provides a method for preparing modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater, and the steps are as follows:

[0070] (1) Weigh 4 g of direct flotation phosphate tailings, 4.5 g of reverse flotation phosphate tailings, and 1.5 g of montmorillonite, mix them evenly, and grind them into 200 mesh (screening rate 80%) using a dry grinder to obtain a mixed powder;

[0071] (2) The mixed powder is placed in a granulator for granulation. During the granulation process, a 5% H2O2 solution is sprayed in, wherein the mass ratio of H2O2 solution to mixed powder is 2:100. After granulation, a round-hole sieve is used to screen out raw material balls with a particle size of 4-6 mm. The balls are placed in an oven at 105°C and dried for 3 hours to obtain dry raw material balls.

[0072] (3) Place the dried raw material balls into a muffle furnace for roasting. The roasting process is as follows: adjust the heating rate to 10°C / min -1 Heat to 450℃ and preheat for 30min, then heat at 5℃·min -1 After heating to 1000°C and keeping the temperature constant for 60 minutes, the furnace is cooled to below 300°C, taken out, and cooled to room temperature to obtain primary tailings ceramsite;

[0073] (4) Prepare rare earth modified solution: at a concentration of 0.05 mol·L -1A 10% HNO3 solution was added to the Ce(NO3)3 solution to adjust the pH to 4-5 to obtain a rare earth modified solution (RE in this embodiment is cerium);

[0074] The original tailings ceramsite was placed in deionized water, and the rare earth modified solution was slowly added dropwise under stirring conditions in a constant temperature water bath of 30-60°C (specifically, the temperature was 60°C and the stirring rate was 30r / min). The addition time was 2h, and the dosage ratio of the original tailings ceramsite, deionized water, and rare earth modified solution was 1g:5mL:5mL. After the addition was completed, the entire system was stirred in a constant temperature water bath for 2h, kept at the original temperature in the constant temperature water bath for aging for 8h, and dried in an oven at 105°C for 2h to obtain modified phosphorus tailings ceramsite for deep treatment of phosphorus-containing wastewater, which was named PTC-03.

[0075] Example 4

[0076] This embodiment provides a method for preparing modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater, and the steps are as follows:

[0077] (1) Weigh 3.5 g of direct flotation phosphate tailings, 4.5 g of reverse flotation phosphate tailings, and 2 g of montmorillonite, mix them evenly, and grind them into 200 mesh (screening rate 80%) using a dry grinder to obtain a mixed powder;

[0078] (2) The mixed powder is placed in a granulator for granulation. During the granulation process, a 5% H2O2 solution is sprayed in, wherein the mass ratio of H2O2 solution to mixed powder is 2:100. After granulation, a round-hole sieve is used to screen out raw material balls with a particle size of 4-6 mm. The balls are placed in an oven at 105°C and dried for 3 hours to obtain dry raw material balls.

[0079] (3) Place the dried raw material balls into a muffle furnace for roasting. The roasting process is as follows: adjust the heating rate to 10°C / min -1 Heat to 350℃ and preheat for 60min, then heat at 10℃·min -1 After heating to 1050°C and keeping the temperature constant for 60 minutes, the product is cooled to below 300°C along with the furnace and taken out, and cooled to room temperature to obtain the original tailings ceramsite;

[0080] (4) Prepare rare earth modified solution: at a concentration of 0.05 mol·L -1 To the LaCl3 solution, add 10% HCl solution to adjust the pH to 4-5 to obtain a rare earth modified solution (RE in this embodiment is lanthanum);

[0081] The original tailings ceramsite was placed in deionized water, and the rare earth modified solution was slowly added dropwise under stirring conditions in a constant temperature water bath of 30-60°C (specifically, the temperature was 45°C and the stirring rate was 30r / min). The addition time was 3 hours, and the dosage ratio of the original tailings ceramsite, deionized water, and rare earth modified solution was 1g:2mL:10mL. After the addition was completed, the entire system was stirred in a constant temperature water bath for 6 hours, kept at the original temperature in the constant temperature water bath for aging for 10 hours, and dried in an oven at 105°C for 2 hours to obtain modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater, which was named PTC-04.

[0082] Comparative Example 1

[0083] The ceramsite preparation steps of Comparative Example are as follows:

[0084] (1) Weigh 4 g of direct flotation phosphate tailings, 4 g of reverse flotation phosphate tailings, and 2 g of montmorillonite, mix them evenly, and grind them into 200 mesh (screening rate 80%) using a dry grinder to obtain a mixed powder;

[0085] (2) The mixed powder is placed in a granulator for granulation. During the granulation process, a 5% H2O2 solution is sprayed in, wherein the mass ratio of H2O2 solution to mixed material is 2:100. After granulation, raw material balls with a particle size of 4-6 mm are sieved with a round hole sieve and placed in a 105°C oven for drying for 3 hours to obtain dry raw material balls;

[0086] (3) Place the dried raw material balls into a muffle furnace for roasting. The roasting process is as follows: adjust the heating rate to 8°C·min -1 Heat to 450℃ and preheat for 30min, then heat at 10℃·min -1 After heating to 950°C and maintaining the temperature for 60 minutes, the furnace was cooled to below 300°C, taken out, and cooled to room temperature to obtain the original tailings ceramsite; named DPC-01.

[0087] Comparative Example 2

[0088] The modified ceramsite preparation steps of the comparative example are as follows:

[0089] (1) Weigh 3.5 g of direct flotation phosphate tailings, 4.5 g of reverse flotation phosphate tailings, and 2 g of montmorillonite, mix them evenly, and grind them into 200 mesh (screening rate 80%) using a dry grinder to obtain a mixed powder;

[0090] (2) The mixed powder is placed in a granulator for granulation. During the granulation process, a 5% H2O2 solution is sprayed in, wherein the mass ratio of H2O2 solution to mixed material is 2:100. After granulation, raw material balls with a particle size of 4-6 mm are sieved with a round hole sieve and placed in a 105°C oven for drying for 3 hours to obtain dry raw material balls;

[0091] (3) Place the dried raw material balls into a muffle furnace for roasting. The roasting process is as follows: adjust the heating rate to 10°C / min -1 Heat to 350℃ and preheat for 60min, then heat at 10℃·min -1 After heating to 950°C and keeping the temperature constant for 60 minutes, the furnace is cooled to below 300°C, taken out, and cooled to room temperature to obtain primary tailings ceramsite;

[0092] (4) Prepare a molar concentration of 0.05 mol·L -1 La(NO3)3 aqueous solution was used as the modification solution;

[0093] The original tailings ceramsite was placed in deionized water, and the rare earth modified solution was slowly added dropwise under the stirring condition of a constant temperature water bath (specific temperature was 30°C, stirring rate was 30r / min). The addition time was 2h, and the amount ratio of the original tailings ceramsite, deionized water, and rare earth modified solution was 1g:5mL:5mL. After the addition was completed, the whole system was stirred in a constant temperature water bath for 4h, kept at the original temperature in a constant temperature water bath for aging for 8h, and dried in an oven at 105°C for 2h to obtain a comparative modified phosphate tailings ceramsite, named DPC-02.

[0094] Example 5

[0095] Weigh 2g each of PTC-01, PTC-02, PTC-03, DPC-01 and DPC-02 and treat 100ml of simulated phosphorus-containing wastewater (total phosphorus concentration 50mg·L) at pH 5. -1 ), treatment time was 4 hours, shaking intensity was 120 rpm, and total phosphorus in wastewater was determined according to the reference standard "Water quality - Determination of total phosphorus - Ammonium molybdate spectrophotometric method" (GB 11893-89).

[0096] The actual picture after processing is as follows Figure 4 As shown in the figure, the effluent water of the simulated phosphorus-containing wastewater treated by PTC-01, PTC-02 and PTC-03 is clear and transparent, while the effluent water of the simulated phosphorus-containing wastewater treated by DPC-01 and DPC-02 is turbid with obvious white flocs. The above water turbidity is mainly caused by water hardness. PTC-01, PTC-02 and PTC-03 are tailings ceramsite modified by the proton balance method. When treating phosphorus-containing wastewater, they will not release Ca 2+ and Mg 2+ , simulated phosphorus-containing wastewater treatment data such as Figure 5 As shown, the effluent Ca 2+ The concentrations were 1.21 mg·L -1 , 1.23mg·L -1 , 1.32mg·L -1 Mg 2+ The concentrations were 0.3 mg·L-1 , 0.15mg·L -1 , 0.32mg·L -1 .

[0097] DPC-01 is unmodified tailings ceramsite, which will release a large amount of Ca when treating phosphorus-containing wastewater. 2+ and Mg 2+ (Ca in water 2+ concentration and Mg 2+ The concentrations were 55 mg·L -1 and 19 mg·L -1 ) and lead to an increase in water hardness, Ca 2+ It will react with phosphate and sulfate in the water to form white flocs, so the effluent of phosphorus-containing wastewater is turbid and white flocs are formed in the water. DPC-02 is a common modified tailings ceramsite, which carries a certain amount of rare earth ions on its surface, which will reduce Ca to a certain extent. 2+ and Mg 2+ release, but because no H is introduced + Promote the large-area loading of rare earth ions on the surface of tailings ceramsite, resulting in Ca 2+ Mg 2+ There is still a certain amount of hydrolysis loss, so similar to DPC-01, the effluent of phosphorus-containing wastewater is turbid, and white flocs are generated in the water body (Ca in the water body 2+ concentration and Mg 2+ The concentrations were 15.6 mg·L -1 and 6.8 mg·L -1 ).

[0098] The four-hour adsorption rate of PTC-01 on phosphate reached 99.72%, and the remaining total phosphorus concentration dropped to 0.18 mg·L -1 The four-hour adsorption rate of PTC-02 on phosphate reached 99.61%, and the remaining total phosphorus concentration dropped to 0.21 mg·L -1 The four-hour adsorption rate of PTC-03 on phosphate reached 99.68%, and the remaining total phosphorus concentration dropped to 0.16 mg·L -1 The three types of tailings ceramsite modified by the proton balance method all achieved deep treatment of simulated phosphorus-containing wastewater. DPC-01 and DPC-02 are unmodified and conventionally modified tailings ceramsite, respectively. Their four-hour adsorption rates for phosphate were 75.6% and 85.5%, respectively, and the residual total phosphorus concentration was reduced to 12.5 mg·L -1 and 7.25 mg·L -1 , have not reached deep treatment, the simulated phosphorus-containing wastewater treatment data are as follows Figure 5The reference standard for the determination of total phosphorus in wastewater is "Water quality - Determination of total phosphorus - Ammonium molybdate spectrophotometry" (GB 11893-89), the reference standard for the determination of calcium ions in water samples is "Water quality - Determination of calcium - EDTA titration method" (GB 7476-87), and the reference standard for the determination of magnesium ions in water samples is "Water quality - Determination of total calcium and magnesium - EDTA titration method" (GB 7477-87).

[0099] Example 6

[0100] Weigh 2g each of PTC-02, PTC-03, PTC-04, DPC-01 and DPC-02 and treat 100ml of actual phosphorus chemical wastewater (total phosphorus concentration of 53.5mg·L) at pH 5. -1 , fluoride ion concentration is 25.69 mg·L -1 , sulfate ion concentration is 56.87 mg·L -1 ), treatment time was 4 hours, and the shaking intensity was 120 rpm.

[0101] Specific data such as Figure 6 As shown, when the concentration of interfering ion fluoride is 25.69 mg·L -1 , sulfate ion concentration is 56.87 mg·L -1 Under the condition of low temperature, the four-hour adsorption rates of phosphate by PTC-02, PTC-03 and PTC-04 reached 99.63%, 99.76% and 99.66%, respectively, and the remaining total phosphorus concentration dropped to 0.186 mg·L -1 , 0.21mg·L -1 , 0.168mg·L -1 The results of deep treatment were achieved, which showed that fluoride ions and sulfate ions did not interfere with the treatment effect of tailings ceramsite modified by proton balance method.

[0102] At the same time, PTC-02, PTC-03, and PTC-04 treat the effluent Ca of phosphorus-containing wastewater. 2+ The concentrations were 1.56 mg·L -1 , 1.83mg·L -1 , 1.94 mg·L -1 Mg 2+ The concentrations were 0.38 mg·L -1 , 0.18mg·L -1 , 0.34mg·L -1 DPC-01 and DPC-02 treat phosphorus-containing wastewater effluent Ca 2+ The concentrations were 57.3 mg·L -1 , 9.86mg·L -1 Mg 2+The concentrations were 19.6 mg·L -1 , 4.89mg·L -1 .

[0103] Example 7

[0104] Weigh 2 g each of PTC-02, PTC-03, PTC-04, DPC-01, and DPC-02 and treat 100 ml of actual phosphorus chemical wastewater (total phosphorus concentration of 209.6 mg·L) at a pH of 5. -1 , fluoride ion concentration was 82.69 mg·L -1 , sulfate ion concentration is 189.87 mg·L -1 ), treatment time was 4 h, and the shaking intensity was 120 rpm.

[0105] Specific data such as Figure 7 As shown in the figure, when the concentration of interfering ion fluoride is 82.69 mg·L -1 , sulfate ion concentration was 189.87 mg·L -1 Under the condition of phosphate absorption, the four-hour adsorption rates of PTC-02, PTC-03 and PTC-04 reached 99.90%, 99.88% and 99.91%, respectively, and the total phosphorus concentration in the effluent was reduced to 0.196 mg·L -1 , 0.234 mg·L -1 , 0.179 mg·L -1 The deep treatment effect was still achieved, which shows that when treating high-concentration phosphorus-containing wastewater, high-concentration fluoride ions and sulfate ions did not interfere with the tailings ceramsite modified by the proton balance method. At the same time, the effluent Ca of PTC-02, PTC-03, and PTC-04 in treating phosphorus-containing wastewater 2+ The concentrations were 1.86 mg·L -1 、1.93 mg·L -1 , 2.04 mg·L -1 Mg 2 + The concentrations were 0.48 mg·L -1 , 0.28 mg·L -1 , 0.44 mg·L -1 The effluent Ca of DPC-01 and DPC-02 for treating phosphorus-containing wastewater 2+ The concentrations were 58.36 mg·L -1 , 24.36 mg·L -1 Mg 2+ The concentrations were 17.36 mg·L -1 , 9.86mg·L -1 .

[0106] Performance Testing

[0107] (1) The chemical composition (%) of PTC-01 prepared in Example 1 was analyzed by X-ray fluorescence spectrometer (XRF). The results are shown in Table 2.

[0108] Table 2 Chemical composition analysis of PTC-01 (%)

[0109]

[0110] It can be seen from the data in Table 2 that the main components of PTC-01 are CaO, SiO2 and MgO, with contents of 36.34%, 26.48% and 17.32% respectively.

[0111] (2) The PTC-01 prepared in Example 1 was tested using an X-ray diffraction analyzer (XRD) and compared with the diffraction file (PDF) card in the standard database. The results are as follows: Figure 1 As shown. Figure 1 It can be seen that the main mineral components of the PTC-01 tailings ceramsite prepared in Example 1 are quartz, marble, periclase and fluorapatite.

[0112] (3) The pore structure parameters and compressive strength of PTC-01, PTC-02, PTC-03, and PTC-04 prepared in Examples 1 to 4 and DPC-01 and DPC-02 prepared in Comparative Examples 1 to 2 were analyzed using a BET tester and a compressive strength tester. The results are shown in Table 3.

[0113] Table 3 Pore structure parameters and compressive strength of the embodiments and comparative examples

[0114]

[0115] It can be seen from the data in Table 3 that Examples 1 to 4 and Comparative Examples 1 to 2 are all mesoporous materials, with an average pore diameter between microporous and macroporous materials, and an average pore diameter of 16.879 nm to 17.023 nm.

[0116] Example 1 Preparation of N2 adsorption-desorption curve and pore size distribution of PTC-01 Figure 2 As shown in the figure, the adsorption-desorption curve of PTC-01 conforms to the type IV adsorption isotherm, which belongs to monolayer adsorption; the middle section of the curve shows an H3 type hysteresis loop, which is speculated to be caused by capillary condensation due to the pores of PTC-01 being narrow slits formed by particle accumulation.

[0117] (4) The microscopic morphology of the PTC-01 prepared in Example 1 before and after adsorption was observed by field emission scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Figure 3As shown in the figure, the SEM images show that the surface of PTC-01 before adsorption exhibits a rough and grooved appearance, with a crisscross pattern of uneven cracks of varying sizes, indicating that it provides a large number of adsorption sites, laying the foundation for the effective capture of phosphate. After the adsorption task is completed, the surface of PTC-01 is evenly covered with a layer of precipitate, forming a dense adsorption layer, which directly reflects the excellent adsorption capacity of PTC-01. EDS scans show that the main elements Si, Al, La, Fe, and O of PTC-01 are evenly distributed before and after adsorption, with no over-enrichment of certain elements. This proves that the PTC-01 prepared in Example 1 provides sufficient reaction space during the adsorption process. Furthermore, the surface scan of PTC-01 after adsorption shows the enrichment of P element, further demonstrating the excellent adsorption performance of PTC-01.

Claims

1. A method for preparing modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater, characterized in that: The following steps are involved: (1) mixing and grinding the forward flotation phosphate tailings, the reverse flotation phosphate tailings, and montmorillonite to obtain a mixed powder; (2) granulating the mixed powder to obtain raw material balls, and drying to obtain dry raw material balls; (3) placing the dried raw material balls in a muffle furnace for roasting to obtain primary tailings ceramsite; (4) placing the original tailings ceramsite in deionized water, adding a rare earth modified solution with a pH of 4 to 5 under stirring in a constant temperature water bath at 30 to 60° C., wherein the rare earth modified solution contains trivalent rare earth ions RE with a concentration of 0.01 to 0.05 mol / L. 3+ , RE is lanthanum and / or cerium; After the dropwise addition is completed, the original temperature is maintained and the mixture is stirred in a constant temperature water bath for 2 to 6 hours, and then the original temperature is maintained and the mixture is allowed to stand and age for 8 to 10 hours. The mixture is taken out and dried to obtain modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater.

2. The method for preparing modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater according to claim 1, wherein: In step (1), the mixed powder contains 35-45% of forward flotation phosphate tailings, 35-45% of reverse flotation phosphate tailings, and 15-20% of montmorillonite by mass percentage, and the sum of the mass percentages of the above components is 100%.

3. The method for preparing modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater according to claim 1, wherein: In step (2), H2O2 solution with a mass concentration of 5-10% is sprayed into the granulation process, wherein the mass ratio of H2O2 solution: mixed powder is (2-5):

100.

4. The method for preparing modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater according to claim 1, wherein: In step (2), granulation is performed to obtain raw material balls with a particle size of 4 to 6 mm, which are placed in an oven at 100 to 110° C. and dried for 2 to 3 hours to obtain dry raw material balls.

5. The method for preparing modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater according to claim 1, wherein: In step (3), the calcination comprises: firstly heating at 8-10°C·min -1 Heat to 350-450℃ at a rate of 30-60min, then heat at 5-10℃·min -1 The temperature is raised to 950-1050° C. at a constant rate for 60-120 min, cooled to below 300° C. in the furnace, taken out, and cooled to room temperature to obtain primary tailings ceramsite.

6. The method for preparing modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater according to claim 1, wherein: In step (4), the rare earth modified solution is obtained by adjusting the pH of an aqueous solution of rare earth nitrate RE(NO3)3 by nitric acid to 4-5, or by adjusting the pH of an aqueous solution of rare earth chloride RECl3 by hydrochloric acid to 4-5; The dosage ratio of the original tailings ceramsite, deionized water and rare earth modified solution is 1g:2-5mL:5-10mL, and the rare earth modified solution is added dropwise for 2-3h.

7. The method for preparing modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater according to claim 1, wherein: In step (4), the product is taken out and dried in an oven at 100-110° C. for 2-3 hours.

8. A modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater, characterized in that: The modified phosphate tailings ceramsite is prepared by the method for preparing the modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater according to any one of claims 1 to 7.

9. An application of the modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater as claimed in claim 8, characterized in that: For deep treatment of total phosphorus concentration 10 mg·L -1 ~1000mg·L -1 , rich in SO4 2- and F - Phosphate industry wastewater containing impurity ions.

10. The use of modified phosphate tailings ceramsite for deep treatment of phosphorus-containing wastewater as claimed in claim 9, characterized in that: The dosage of the modified phosphate tailings ceramsite is 10g·L -1 ~120g·L -1 .

Images