Preparation method of rare earth composite fluoride removal agent, rare earth composite fluoride removal agent and application

Abstract

The application discloses a preparation method of a rare earth composite fluorine removal agent, the rare earth composite fluorine removal agent and application. The preparation method of the rare earth composite fluorine removal agent comprises the following steps: S1, adding a heavy metal capturing agent into a rare earth ore slag raffinate to perform metal impurity adsorption treatment, removing the heavy metal capturing agent after the adsorption treatment, and obtaining an intermediate treatment liquid; S2, preheating the intermediate treatment liquid to obtain a preheated material; S3, evaporating and concentrating the preheated material to obtain a concentrated liquid; and S4, cooling and crystallizing to obtain the rare earth composite fluorine removal agent. The rare earth composite fluorine removal agent for water treatment is prepared by performing resource treatment on a rare earth raffinate, and the fluorine removal agent product is prepared by the process, so that the fluorine removal agent with high efficiency is prepared by using cheap and easily obtained raw materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial fluorine-containing wastewater treatment, and particularly to a preparation method of a rare earth composite fluorine removal agent, the rare earth composite fluorine removal agent and application. BACKGROUND

[0002] In recent years, industrial fluorine-containing wastewater has a large discharge volume and a high fluorine content, which seriously threatens the living environment and human health, and therefore attracts close attention of the society. Fluoride pollution is paid more and more attention by people, and how to treat fluorides in wastewater has been an important issue in the field of environmental protection at home and abroad. In recent years, a lot of work has been done in the treatment of fluorine-containing wastewater at home and abroad, and great progress has been made in the theoretical knowledge, methods and technologies of fluorine removal. At present, the industrial wastewater containing fluorine treated at home and abroad has complex components, and many treatment methods are available, such as the precipitation method and the adsorption method, and also including the ion exchange resin method, the reverse osmosis method, the electrocoagulation method, the electrodialysis method and the like.

[0003] In the actual defluorination process of a factory, the defluorination efficiency and economy are comprehensively considered according to different environments and defluorination requirements, so as to determine the fluorine-containing wastewater treatment method and process, so as to achieve good defluorination effect and good economy, and thus achieve the purpose of treating fluorine-containing wastewater and resource utilization.

[0004] Therefore, how to use cheap and readily available raw materials to make efficient fluorine removal agents has become a technical problem. SUMMARY

[0005] In view of the limitations of the prior art, the present application provides a preparation method of a rare earth composite fluorine removal agent, the rare earth composite fluorine removal agent and application. The present application realizes the use of cheap and readily available raw materials to make efficient fluorine removal agents by preparing a rare earth composite fluorine removal agent for water treatment through resource treatment of a rare earth raffinate and the fluorine removal agent product prepared thereby.

[0006] To achieve the above object, the present application adopts the following technical scheme:

[0007] The first aspect of the present application is to provide a preparation method of a rare earth composite fluorine removal agent, comprising the following steps:

[0008] S1: adding a heavy metal capturing agent to a rare earth slag raffinate for metal impurity adsorption treatment, removing the heavy metal capturing agent after the adsorption treatment, and obtaining an intermediate treatment liquid;

[0009] S2: preheating the intermediate treatment liquid to obtain a preheated material;

[0010] S3: evaporating and concentrating the preheated material to obtain a concentrated liquid;

[0011] S4: cooling and crystallizing to obtain a rare earth composite fluorine removal agent.

[0012] As a preferred embodiment, step S1,

[0013] The rare earth ore slag raffinate at least includes Al, Ti, Fe, Pb, Cr, As, Cd or Hg elements; preferably, in the rare earth ore slag raffinate, the content of aluminum element is 4% to 6% in terms of the mass content of aluminum oxide;

[0014] Further preferably,

[0015] The preparation step of the rare earth ore slag raffinate is: once acid dissolution of the rare earth ore slag to obtain a primary acid solution, organic extraction of the primary acid solution to obtain the rare earth ore slag raffinate.

[0016] More preferably,

[0017] The acid solution added in the primary acid dissolution is a sulfuric acid solution; more preferably, the mass concentration of the sulfuric acid solution is 50%;

[0018] The organic solvent added in the organic extraction is an amine extractant; preferably, the organic solvent is at least one of N1923, N263 or N235; the extraction phase ratio is 1:1 to 3:1, and the extraction operation temperature is 30°C to 50°C.

[0019] As a preferred embodiment, step S1,

[0020] The heavy metal capturing agent is added to the rare earth ore slag raffinate and is allowed to stand and adsorb at 20 to 50°C for 50 to 80 min; the heavy metal capturing agent is removed by filtration to obtain the intermediate treatment liquid;

[0021] Preferably, after standing and adsorbing, an auxiliary solution is added and micro-bubbles are introduced for 20 to 30 min, and then the heavy metal capturing agent is removed by filtration to obtain the intermediate treatment liquid;

[0022] Further preferably,

[0023] The mass ratio of the rare earth ore slag raffinate to the heavy metal capturing agent is 1 ton of rare earth ore slag raffinate: 1 to 3 g of heavy metal capturing agent; and / or,

[0024] The auxiliary agent is selected from polypropylene amine hydrochloride; and / or,

[0025] The concentration of the auxiliary solution is 0.2 to 1 wt%; and / or,

[0026] The particle size of the micro-bubbles is 300 to 600 nm; and / or,

[0027] The mass ratio of the auxiliary agent to the heavy metal capturing agent is 1:5 to 10; and / or,

[0028] The aeration amount of the micro-bubbles is 5 L / (m2 • h) ~ 10 L / (m 2 • h).

[0029] The present application surprisingly finds that, under the action of microbubbles, the addition of an auxiliary agent can synergize with a heavy metal capturing agent to improve the absorption effect on heavy metal ions, which is helpful to improve the performance of the prepared heavy rare earth composite fluorine removal agent.

[0030] As a preferred embodiment, step S1,

[0031] The heavy metal capturing agent is graphene oxide grafted with a phosphorus-containing group; preferably,

[0032] The preparation method of the heavy metal capturing agent comprises the following steps:

[0033] (1) Raw material mixing: dispersing graphene oxide in a phosphorous acid solution to obtain a graphene oxide dispersion;

[0034] (2) Ultrasonic peeling: ultrasonic treatment of the graphene oxide dispersion; to obtain a graphene oxide suspension;

[0035] (3) Adding a catalyst: adding a catalyst to the graphene oxide suspension, ultrasonic dispersion again, vacuum drying, to obtain a mixture of graphene oxide and phosphorus trichloride;

[0036] (4) Preparation of the heavy metal capturing agent: high-temperature heat treatment of the mixture of graphene oxide and phosphorus trichloride under a protective atmosphere to obtain the heavy metal capturing agent.

[0037] The heavy metal capturing agent of the present application has specific functional groups through grafting modification, has high selectivity for heavy metal ions, and can remove heavy metal ion pollutants in a targeted manner. The preparation process of the heavy metal capturing agent of the present application is that the carboxyl groups on the surface layer of graphene oxide can react with phosphorous acid under the catalysis of phosphorus trichloride, the double bond of the carboxyl group is opened, and a phosphorus-containing group is grafted thereon. The phosphorus-containing group of the modified graphene oxide fixes heavy metal ions, and filtration of the solid capturing agent can achieve the effect of removing heavy metals.

[0038] As a preferred embodiment, step (1),

[0039] The mass-to-volume ratio of the graphene oxide to the phosphorous acid solution is 1-5 mg: 1; and / or,

[0040] The mass concentration of the phosphorous acid solution is 10%-50%; and / or,

[0041] Step (2),

[0042] The ultrasonic treatment time is 10-60 min; and / or,

[0043] The power of the ultrasonic treatment is 100w-1000w.

[0044] As a preferred embodiment, step (3),

[0045] The catalyst is phosphorus trichloride; and / or,

[0046] The mass ratio of the catalyst to the graphite oxide is 1-5:1; and / or,

[0047] The time of the secondary ultrasonic dispersion is 10min-60min; and / or,

[0048] The power of the secondary ultrasonic treatment is 100w-1000w; and / or,

[0049] The temperature of the vacuum drying is 50-80℃; and / or,

[0050] Step (4),

[0051] The temperature of the high-temperature heat treatment is 700℃-900℃; and / or,

[0052] The time of the high-temperature heat treatment is 30-60min; and / or,

[0053] The protective atmosphere is nitrogen.

[0054] As a preferred embodiment, step S2:

[0055] The intermediate treatment liquid is sequentially preheated by a tail gas preheater, a two-effect condensate water preheater and a one-effect condensate water preheater to obtain preheated material, and the temperature of the preheated material is 40-60℃;

[0056] Preferably,

[0057] The temperature of the tail gas in the tail gas preheater is 40-60℃; and / or,

[0058] The temperature of the heat exchange medium in the two-effect condensate water preheater is 90-100℃; and / or,

[0059] The temperature of the heat exchange medium in the one-effect condensate water preheater is 130-140℃.

[0060] The present application fully utilizes the heat of the high-temperature condensate water by the above heat exchange mode, which is beneficial to resource conservation.

[0061] As a preferred embodiment, step S3: the preheated material is evaporated and concentrated by a two-effect evaporator and a single-effect evaporator to obtain concentrated liquid; preferably,

[0062] The temperature of the two-effect evaporator is 90-100℃; and / or,

[0063] The pressure of the double-effect evaporator is 0.1-0.3 MPa; and / or,

[0064] The evaporation time of the double-effect evaporator is 0.1-1 h; and / or,

[0065] The temperature of the single-effect evaporator is 100-110 DEG C; and / or,

[0066] The pressure of the single-effect evaporator is 0.2-0.5 MPa; and / or,

[0067] The single-effect evaporation time of the single-effect evaporator is 0.1-1 h; and / or,

[0068] In the present application, the double-effect evaporator and the single-effect evaporator are both graphite evaporators for evaporation and concentration; the graphite evaporator is heated by steam. In general, the round block hole type graphite evaporator is more suitable. The round block hole type graphite evaporator is composed of graphite air cavity, graphite upper and lower end cover, graphite heat exchange block, carbon steel shell and pressure spring. The graphite heat exchange block is drilled with horizontal holes and vertical holes, which are not communicated, the vertical holes pass corrosive materials, and the horizontal holes pass steam. The two graphite heat exchange blocks are sealed by polytetrafluoroethylene sealing element. Compared with the prior art, the graphite material solves the problems of pipeline corrosion and easy blockage in actual production process.

[0069] In addition, the present application finds that the performance of the prepared heavy rare earth composite fluorine removal agent is improved by setting the process of two-stage evaporation.

[0070] S4: cooling crystallization by a flaking machine to obtain the rare earth composite fluorine removal agent;

[0071] Preferably,

[0072] The temperature of the cooling crystallization is 70-80 DEG C; and / or, the rotating speed of the flaking machine is 10-20 r / min.

[0073] The above-mentioned crystallization step adopts a large-scale roller type structure, and the stock bin adopts a polytetrafluoroethylene lining layer, which is more corrosion-resistant and has a longer service life compared with the traditional carbon steel material.

[0074] The second aspect of the present application is to provide the rare earth composite fluorine removal agent prepared by the preparation method of the rare earth composite fluorine removal agent described in the first aspect of the present application, and the composition of the rare earth composite fluorine removal agent includes hydrated aluminum sulfate, aluminum chloride and rare earth oxide; wherein the content of aluminum element is calculated as aluminum oxide, the mass content of aluminum oxide is 8%-20%; the mass content of rare earth element is 0.1%-5%; preferably, the mass content of aluminum oxide is 10%-16%; further preferably, the mass content of aluminum oxide is 12.5%-16%; more preferably, the mass content of aluminum oxide is 14%-16%.

[0075] The mass content of the rare earth element in the rare earth composite fluorine removal agent is 0.6% to 2%; preferably, the mass content of the rare earth element is 0.9% to 2%; and more preferably, the mass content of the rare earth element is 1.6% to 2%.

[0076] The rare earth composite fluorine removal agent of the present application not only has high concentration of aluminum sulfate for fluorine removal, but also has appropriate amount of rare earth elements, and the rare earth oxides form colloids in water to adsorb fluorine ions. In addition, the rare earth elements form hardly soluble compounds such as LaF3 with fluorine, so that the fluorine in water is removed; therefore, the rare earth elements of the present application also improve the fluorine removal effect.

[0077] The third aspect of the present application is to provide the use of the rare earth composite fluorine removal agent of the second aspect of the present application in fluorine removal.

[0078] Compared with the prior art, the present application has at least the following advantages:

[0079] (1) The present application prepares the rare earth composite fluorine removal agent for water treatment by resource treatment of the rare earth raffinate, and the process and the fluorine removal agent product prepared thereby. The process of the present application is a continuous process with high degree of automation, which is beneficial to operation; the process of the present application includes mature evaporation concentration process, and the equipment runs stably and reliably; the heater used in the process of the present application is not easy to scale or block, and the heater can be selected from graphite material, thereby saving cost; the process of the present application requires less auxiliary equipment, and the device is compact, has small floor area, small temperature difference loss, and is high in efficiency and energy saving.

[0080] (2) The fluorine removal agent prepared by the process of the present application has lower dosage and less mud production, and the dosage is reduced by 10% to 20% and the mud production is reduced by 15% to 25% compared with the conventional fluorine removal agent and PAC on the market. BRIEF DESCRIPTION OF DRAWINGS

[0081] Figure 1 The process flow chart of the preparation method of the rare earth composite fluorine removal agent of the present application. DETAILED DESCRIPTION

[0082] The present application will be specifically described below in combination with specific examples, and it is necessary to point out here that the following examples are only used for further illustration of the present application, and cannot be understood as limiting the protection scope of the present application, and some non-essential improvements and adjustments of the present application by the person skilled in the art according to the content of the present application still belong to the protection scope of the present application.

[0083] Preparation Example 1

[0084] The heavy metal capturing agent of the present application is graphene oxide grafted with modified phosphorus-containing groups; the preparation method thereof comprises the following steps:

[0085] (1) raw material mixing: disperse the graphite oxide in the phosphorous acid solution, the mass-volume ratio of the graphite oxide and the phosphorous acid solution is 100 mg: 50 ml; the mass concentration of the phosphorous acid solution is 10%; obtain the graphite oxide dispersion liquid;

[0086] (2) ultrasonic stripping: ultrasonic treatment to the graphite oxide dispersion liquid, the ultrasonic treatment time is 10 min; the ultrasonic treatment power is 100 w; obtain the graphene oxide suspension;

[0087] (3) adding catalyst: add the catalyst phosphorus trichloride to the graphene oxide suspension, the mass ratio of the phosphorus trichloride and the graphite oxide is 1:1; ultrasonic dispersion again, the ultrasonic dispersion time is 10 min; the power is 100 w; vacuum drying, the vacuum drying temperature is 50 DEG C; obtain the mixture of the graphene oxide and the phosphorus trichloride;

[0088] (4) preparation of heavy metal capturing agent: high temperature heat treatment to the mixture of the graphene oxide and the phosphorus trichloride under nitrogen, the high temperature heat treatment temperature is 700 DEG C, the time is 30 min; obtain the heavy metal capturing agent.

[0089] Preparation Example 2

[0090] The heavy metal capturing agent of the application is the graphene oxide grafted with the phosphorus-containing group; the preparation method comprises the following steps:

[0091] (1) raw material mixing: disperse the graphite oxide in the phosphorous acid solution, the mass-volume ratio of the graphite oxide and the phosphorous acid solution is 100 mg: 50 ml; the mass concentration of the phosphorous acid solution is 30%; obtain the graphite oxide dispersion liquid;

[0092] (2) ultrasonic stripping: ultrasonic treatment to the graphite oxide dispersion liquid, the ultrasonic treatment time is 30 min; the ultrasonic treatment power is 500 w; obtain the graphene oxide suspension;

[0093] (3) adding catalyst: add the catalyst phosphorus trichloride to the graphene oxide suspension, the mass ratio of the phosphorus trichloride and the graphite oxide is 3:1; ultrasonic dispersion again, the ultrasonic dispersion time is 30 min; the power is 500 w; vacuum drying, the vacuum drying temperature is 60 DEG C; obtain the mixture of the graphene oxide and the phosphorus trichloride;

[0094] (4) preparation of heavy metal capturing agent: high temperature heat treatment to the mixture of the graphene oxide and the phosphorus trichloride under nitrogen, the high temperature heat treatment temperature is 800 DEG C, the time is 40 min; obtain the heavy metal capturing agent.

[0095] Preparation Example 3

[0096] The heavy metal capturing agent of the present application is graphene oxide grafted with phosphorus-containing groups; the preparation method thereof comprises the following steps:

[0097] (1) raw material mixing: dispersing the oxidized graphite in a phosphorous acid solution, the mass-volume ratio of the oxidized graphite to the phosphorous acid solution being 100 mg: 50 ml; the mass concentration of the phosphorous acid solution being 50%; obtaining an oxidized graphite dispersion liquid;

[0098] (2) ultrasonic peeling: ultrasonically treating the oxidized graphite dispersion liquid, the ultrasonic treatment time being 60 min; the ultrasonic treatment power being 1000 w; obtaining a graphene oxide suspension liquid;

[0099] (3) adding a catalyst: adding a catalyst phosphorus trichloride to the graphene oxide suspension liquid, the mass ratio of the phosphorus trichloride to the oxidized graphite being 5:1; ultrasonically dispersing again, the ultrasonic dispersion time being 60 min; the power being 1000 w; vacuum drying, the vacuum drying temperature being 80℃; obtaining a graphene oxide and phosphorus trichloride mixture;

[0100] (4) preparation of the heavy metal capturing agent: high-temperature heat treating the graphene oxide and phosphorus trichloride mixture under nitrogen, the high-temperature heat treatment temperature being 900℃, the time being 60 min; obtaining the heavy metal capturing agent.

[0101] Example 1

[0102] It uses the heavy metal capturing agent prepared in Preparation Example 1 to prepare a rare earth composite fluorine removal agent, and the preparation method of the rare earth composite fluorine removal agent is as shown in Figure 1 , comprising the following steps:

[0103] S1: primary acid dissolution of the rare earth slag, the acid solution added in the primary acid dissolution being a 50% mass concentration sulfuric acid solution; the acid dissolution temperature being 25℃, the acid dissolution time being 60 min; obtaining a primary acid solution, and performing organic extraction on the primary acid solution, the organic solvent added in the organic extraction being N1923; the extraction phase ratio being 1:1, and the extraction operation temperature being 30℃; obtaining the rare earth slag raffinate liquid, the rare earth slag raffinate liquid at least comprising heavy metal elements such as Al, Ti, Fe, Pb, Cr, As, Cd and Hg; the heavy metal content of the rare earth slag raffinate liquid being as shown in Table 1.

[0104] Table 1

[0105]

[0106]

[0107] The heavy metal capturing agent is added to the rare earth ore residue liquid and adsorbed for 70 minutes at 20℃ to remove metal impurities, and the mass ratio of the rare earth ore residue liquid to the heavy metal capturing agent is 1 ton of the rare earth ore residue liquid to 1 g of the heavy metal capturing agent; the heavy metal capturing agent is removed after the adsorption treatment to obtain an intermediate treatment liquid;

[0108] S2: The intermediate treatment liquid is preheated in sequence through a tail gas preheater, a two-effect condensate water preheater, and a one-effect condensate water preheater to obtain a preheated material; wherein the temperature of the tail gas in the tail gas preheater is 40℃; the temperature of the heat exchange medium (water) in the two-effect condensate water preheater is 90℃; the temperature of the heat exchange medium (water) in the one-effect condensate water preheater is 130℃; and the temperature of the preheated material is 41℃; the above preheating can fully utilize the heat of the high-temperature condensate water and utilize resources.

[0109] S3: The preheated material is evaporated and concentrated through a two-effect evaporator and a single-effect evaporator (both the two-effect evaporator and the single-effect evaporator are existing graphite evaporators) to obtain a concentrated liquid; and the evaporation and concentration are performed;

[0110] wherein the temperature of the two-effect evaporator is 90℃; the pressure of the two-effect evaporator is 0.1 MPa; the evaporation time of the two-effect evaporator is 0.1 h; the temperature of the single-effect evaporator is 100℃; the pressure of the single-effect evaporator is 0.2 MPa; and the single-effect evaporation time of the single-effect evaporator is 0.1 h;

[0111] S4: The concentrated liquid is cooled and crystallized through a flaking machine; the temperature of the cooling and crystallization is 75℃; and the rotating speed of the flaking machine is 13 r / min to obtain a rare earth composite fluorine removal agent. In the above crystallization step, the flaking machine adopts a large-scale roller type structure, and the stock bin is lined with a fluorine material, which is more corrosion-resistant and has a longer service life than a traditional carbon steel material.

[0112] The rare earth composite fluorine removal agent prepared by the above method mainly includes hydrated aluminum sulfate, aluminum chloride, and rare earth oxides, wherein the content of aluminum elements is calculated based on aluminum oxide, and the specific content is shown in Table 2.

[0113] Example 2

[0114] The method used is basically the same as that of Example 1, except that the heavy metal capturing agent prepared in Preparation Example 2 is used.

[0115] The rare earth composite fluorine removal agent prepared by the above method mainly includes hydrated aluminum sulfate, aluminum chloride, and rare earth oxides, wherein the content of aluminum elements is calculated based on aluminum oxide, and the specific content is shown in Table 2.

[0116] Example 3

[0117] The method used is basically the same as that of Example 1, except that the heavy metal capturing agent prepared in Preparation Example 3 is used.

[0118] The rare earth composite fluorine removal agent prepared by the above method mainly comprises hydrated aluminum sulfate, aluminum chloride and rare earth oxides, wherein the content of aluminum element, calculated as aluminum oxide, is shown in Table 2.

[0119] Example 4

[0120] The method is basically the same as that of Example 1, except that in step S1, the heavy metal capturing agent is added to the rare earth residue liquid, and the metal impurity adsorption treatment is carried out at 20°C for 50 min. Then, the solution of the auxiliary polypropylene amine hydrochloride (concentration of 0.7 wt%) is added and the micro-bubbles are introduced for 20 min, wherein the mass ratio of the auxiliary agent to the heavy metal capturing agent is 1:8. The micro-bubbles are prepared by the existing micro-bubble equipment with air and water, and the particle size of the micro-bubbles is 300-600 nm. The aeration amount of the micro-bubbles is 7 L / (m 2 ·h). Finally, the heavy metal capturing agent is removed by filtration to obtain the intermediate treatment liquid.

[0121] The rare earth composite fluorine removal agent prepared by the above method mainly comprises hydrated aluminum sulfate, aluminum chloride and rare earth oxides, wherein the content of aluminum element, calculated as aluminum oxide, is shown in Table 2.

[0122] Example 5

[0123] The method is basically the same as that of Example 1, except that in step S1, the heavy metal capturing agent is added to the rare earth residue liquid, and the metal impurity adsorption treatment is carried out at 20°C for 55 min. Then, the solution of the auxiliary polypropylene amine hydrochloride (concentration of 0.4 wt%) is added and the micro-bubbles are introduced for 25 min, wherein the mass ratio of the auxiliary agent to the heavy metal capturing agent is 1:6. The micro-bubbles are prepared by the existing micro-bubble equipment with air and water, and the particle size of the micro-bubbles is 300-600 nm. The aeration amount of the micro-bubbles is 5 L / (m 2 ·h). Finally, the heavy metal capturing agent is removed by filtration to obtain the intermediate treatment liquid.

[0124] The rare earth composite fluorine removal agent prepared by the above method mainly comprises hydrated aluminum sulfate, aluminum chloride and rare earth oxides, wherein the content of aluminum element, calculated as aluminum oxide, is shown in Table 2.

[0125] Example 6

[0126] The heavy metal capturing agent prepared in Preparation Example 3 is used to prepare the rare earth composite fluorine removal agent. The preparation method of the rare earth composite fluorine removal agent comprises the following steps:

[0127] S1: The same rare earth ore slag raffinate as in Example 1 was used; a heavy metal capturing agent was added to the rare earth ore slag raffinate, and the mixture was allowed to stand for 65 min at 35℃ for adsorption of metal impurities; the mass ratio of the rare earth ore slag raffinate to the heavy metal capturing agent was 1 ton of rare earth ore slag raffinate: 3 g of heavy metal capturing agent; then a solution of the auxiliary agent polyallylamine hydrochloride (concentration of 0.6 wt%) was added and microbubbles were introduced for 20 min, wherein the mass ratio of the auxiliary agent to the heavy metal capturing agent was 1:7; the microbubbles were microbubbles prepared by existing microbubble equipment by passing air and water through the equipment, and the particle size of the microbubbles was 300-600 nm; the amount of air introduced into the microbubbles was 6 L / (m 2 ·h); finally, the heavy metal capturing agent was removed by filtration to obtain the intermediate treatment liquid.

[0128] A heavy metal capturing agent was added to the rare earth ore slag raffinate, and the mixture was allowed to stand for 50-80 min at 20℃ for adsorption of metal impurities to obtain an intermediate treatment liquid;

[0129] S2: The intermediate treatment liquid was preheated in sequence by a tail gas preheater, a two-effect condensate water preheater, and a one-effect condensate water preheater to obtain a preheated material; wherein the temperature of the tail gas in the tail gas preheater was 45℃; the temperature of the heat exchange medium in the two-effect condensate water preheater was 95℃; the temperature of the heat exchange medium in the one-effect condensate water preheater was 135℃; and the temperature of the preheated material was 45℃; the above preheating can make full use of the heat of high-temperature condensate water and also utilize resources.

[0130] S3: The preheated material was evaporated and concentrated by a two-effect evaporator and a single-effect evaporator (both the two-effect evaporator and the single-effect evaporator were existing graphite evaporators) to obtain a concentrated liquid; the evaporation and concentration were performed;

[0131] Wherein, the temperature of the two-effect evaporator was 95℃; the pressure of the two-effect evaporator was 0.2 MPa; the evaporation time of the two-effect evaporator was 1 h; the temperature of the single-effect evaporator was 110℃; the pressure of the single-effect evaporator was 0.3 MPa; and the single-effect evaporation time of the single-effect evaporator was 1 h;

[0132] S4: Cooling crystallization was performed by a flaking machine; the temperature of the cooling crystallization was 80℃; and the rotating speed of the flaking machine was 15 r / min to obtain a rare earth composite fluorine removal agent. In the above crystallization step, a large-scale drum-type flaking machine was used, and the material bin was made of tetrafluoro material, which was more corrosion-resistant and had a longer service life than traditional carbon steel material.

[0133] The main components of the rare earth composite fluorine removal agent prepared by the above method included hydrated aluminum sulfate, aluminum chloride, and rare earth oxides, wherein the content of aluminum element, calculated as aluminum oxide, was shown in Table 2.

[0134] Comparative Example 1

[0135] The same method as in Example 1 was employed, except that no heavy metal capturing agent was added.

[0136] The rare earth composite fluoride removal agent prepared by the above method mainly comprises hydrated aluminum sulfate, aluminum chloride and rare earth oxides, wherein the aluminum element content, calculated as aluminum oxide, is shown in Table 2.

[0137] Comparative Example 2

[0138] The same method as in Example 1 was employed, except that the evaporation and concentration conditions of the first evaporator were adjusted to be the same as those of the second evaporator.

[0139] The rare earth composite fluoride removal agent prepared by the above method mainly comprises hydrated aluminum sulfate, aluminum chloride and rare earth oxides, wherein the aluminum element content, calculated as aluminum oxide, is shown in Table 2.

[0140] Comparative Example 3

[0141] The same method as in Example 1 was employed, except that the evaporation and concentration conditions of the second evaporator were adjusted to be the same as those of the first evaporator.

[0142] The rare earth composite fluoride removal agent prepared by the above method mainly comprises hydrated aluminum sulfate, aluminum chloride and rare earth oxides, wherein the aluminum element content, calculated as aluminum oxide, is shown in Table 2.

[0143] Comparative Example 4

[0144] The same method as in Example 4 was employed, except that only micro-bubbles were introduced and no additives were added.

[0145] The rare earth composite fluoride removal agent prepared by the above method mainly comprises aluminum sulfate hydrate, aluminum chloride hydrate and rare earth oxides, and the specific contents are shown in Table 2.

[0146] Comparative Example 5

[0147] The same method as in Example 4 was employed, except that no micro-bubbles were introduced and only additives were added.

[0148] The rare earth composite fluoride removal agent prepared by the above method mainly comprises aluminum sulfate hydrate, aluminum chloride hydrate and rare earth oxides, and the specific contents are shown in Table 2.

[0149] The main components of the fluoride removal agents prepared in the above examples and comparative examples are shown in Table 2.

[0150] Table 2

[0151]

[0152]

[0153] Test method: The defluorination rate performance test of the defluorination agent of the examples and the comparative examples on different concentrations of fluorine-containing water quality is performed, and the test method refers to HJ 488-2009 "Determination of Fluoride in Water - Fluoride Reagent Spectrophotometry".

[0154] Application examples 1-6

[0155] Since the pH of the fluorine-containing wastewater is 6, the pH does not need to be adjusted, and 1 mL of the rare earth defluorination agent of the application examples 1-6 is added into the fluorine-containing wastewater (F - The concentration is about 20 mg / L), stirring for 5 min, standing for 5 min, and detecting the F - The concentration of the supernatant. After filtration, wet sludge is obtained, and after drying, the weight is measured.

[0156] Application comparative examples 1-5

[0157] Since the pH of the fluorine-containing wastewater is 6, the pH does not need to be adjusted, and 1 mL of the rare earth defluorination agent of the application examples 1-6 is added into the fluorine-containing wastewater (F - The concentration is about 20 mg / L), stirring for 5 min, standing for 5 min, and detecting the F - The concentration of the supernatant. After filtration, wet sludge is obtained, and after drying, the weight is measured.

[0158] Application comparative example 6

[0159] Since the pH of the fluorine-containing wastewater is 6, the pH does not need to be adjusted, and 1 mL of the rare earth defluorination agent of the application examples 1-6 is added into the fluorine-containing wastewater (F - The concentration is about 20 mg / L), stirring for 5 min, standing for 5 min, and detecting the F - The concentration of the supernatant. After filtration, wet sludge is obtained, and after drying, the weight is measured.

[0160] The defluorination effects of the defluorination agents prepared in the above examples and comparative examples are shown in Table 3.

[0161] Table 3

[0162]

[0163]

[0164] The results show that the application is suitable for the treatment of low-concentration fluorine-containing wastewater (F-≤20 mg / L), and the effluent F - The concentration is ≤0.5 mg / L, and the defluorination effect is good. Compared with the conventional defluorination agent, the rare earth composite defluorination agent produced by the process can not only save the amount of PAC, but also reduce the amount of sludge.

[0165] It is understood that the above embodiments are only exemplary for illustrating the principles of the present application, and the present application is not limited thereto. Various modifications and improvements can be made by those skilled in the art without departing from the spirit and scope of the present application, and these modifications and improvements are also considered as the protection scope of the present application.

Claims

1. A method for preparing a rare earth complex defluorination agent, characterized in that, The method comprises the following steps: S1: adding a heavy metal capturing agent to the rare earth ore slag raffinate to adsorb metal impurities, removing the heavy metal capturing agent after adsorption treatment, and obtaining an intermediate treatment liquid; Step S1, The heavy metal capturing agent is added to the rare earth ore slag raffinate and is allowed to stand and adsorb for 50-80 min at 20-50°C; After standing and adsorption, an auxiliary solution is added and micro-bubbles are introduced for 20-30 min, and then the heavy metal capturing agent is removed by filtration to obtain the intermediate treatment liquid; The rare earth ore slag raffinate at least contains Al, Ti, Fe, Pb, Cr, As, Cd or Hg elements; in the rare earth ore slag raffinate, the content of aluminum element is 4%-6% in terms of the mass content of aluminum oxide; The preparation step of the rare earth ore slag raffinate is: once acid dissolution of the rare earth ore slag to obtain a once acid solution, and organic extraction of the once acid solution to obtain the rare earth ore slag raffinate; The heavy metal capturing agent is graphene oxide grafted with a modified phosphorus-containing group; The preparation method of the heavy metal capturing agent comprises the following steps: (1) raw material mixing: dispersing the graphite oxide in a phosphorous acid solution to obtain a graphite oxide dispersion; (2) ultrasonic stripping: ultrasonic treatment of the graphite oxide dispersion; obtaining a graphene oxide suspension; (3) adding a catalyst: adding a catalyst to the graphene oxide suspension, ultrasonic dispersion again, vacuum drying, and obtaining a mixture of graphene oxide and phosphorus trichloride; (4) preparation of the heavy metal capturing agent: high-temperature heat treatment of the mixture of graphene oxide and phosphorus trichloride under a protective atmosphere to obtain the heavy metal capturing agent; S2: preheating the intermediate treatment liquid to obtain a preheated material; S3: evaporative concentration of the preheated material to obtain a concentrated liquid; S4: cooling and crystallization to obtain the rare earth composite fluorine removal agent.

2. The preparation method of the rare earth composite fluorine removal agent according to claim 1, characterized in that, Step S1, The mass ratio of the rare earth ore slag raffinate to the heavy metal capturing agent is 1 ton of rare earth ore slag raffinate: 1-3 g of heavy metal capturing agent; and / or, The auxiliary agent is selected from polypropylene amine hydrochloride; and / or, The concentration of the auxiliary agent solution is 0.2-1 wt%; and / or, The particle size of the micro-bubbles is 300-600 nm; and / or, The mass ratio of the auxiliary agent to the heavy metal capturing agent is 1:5-10; and / or, The aeration amount of the micro-bubbles is 5 L / (m²·h)-10 L / (m²·h).

3. The preparation method of the rare earth composite fluorine removal agent according to claim 1, characterized in that, Step (1), The mass-to-volume ratio of the graphite oxide to the phosphorous acid solution is 1-5 mg: 1 ml; and / or, The mass concentration of the phosphorous acid solution is 10%-50%; and / or, Step (2), The ultrasonic treatment time is 10 min-60 min; and / or, The ultrasonic treatment power is 100 w-1000 w.

4. The preparation method of the rare earth composite fluorine removal agent according to claim 1, characterized in that, Step (3), The catalyst is phosphorus trichloride; and / or, The mass ratio of the catalyst to the oxidized graphite is 1-5:1; and / or, The time for the second ultrasonic dispersion is 10-60 minutes; and / or, The power for the second ultrasonic treatment is 100-1000w; and / or, The temperature for the vacuum drying is 50-80℃; and / or, Step (4), The temperature for the high-temperature heat treatment is 700-900℃; and / or, The time for the high-temperature heat treatment is 30-60 minutes; and / or, The protective atmosphere is nitrogen.

5. The preparation method of the rare earth composite fluorine removal agent according to claim 1, wherein, Step S2: The intermediate treatment liquid is preheated in sequence by a tail gas preheater, a two-effect condensate water preheater and a one-effect condensate water preheater to obtain preheated material, and the temperature of the preheated material is 40-60℃.

6. The preparation method of the rare earth composite fluorine removal agent according to claim 5, wherein, The temperature of the tail gas in the tail gas preheater is 40-60℃; and / or, The temperature of the heat exchange medium in the two-effect condensate water preheater is 90-100℃; and / or, The temperature of the heat exchange medium in the one-effect condensate water preheater is 130-140℃.

7. The preparation method of the rare earth composite fluorine removal agent according to claim 1, wherein, Step S3: the preheated material is concentrated by evaporation through a two-effect evaporator and a single-effect evaporator to obtain concentrated liquid; S4: cooling crystallization is performed by a flaking machine to obtain the rare earth composite fluorine removal agent.

8. The preparation method of the rare earth composite fluorine removal agent according to claim 7, wherein, Step S3: the temperature of the two-effect evaporator is 90-100℃; and / or, The pressure of the two-effect evaporator is 0.1-0.3MPa; and / or, The evaporation time of the two-effect evaporator is 0.1-1h; and / or, The temperature of the single-effect evaporator is 100-110℃; and / or, The pressure of the single-effect evaporator is 0.2-0.5MPa; and / or, The single-effect evaporation time of the single-effect evaporator is 0.1-1h; and / or, Step S4: The temperature of the cooling crystallization is 70-80℃; and / or, the rotating speed of the flaking machine is 10-20 r / min.

9. A rare earth complex fluorine removing agent produced by the method of producing a rare earth complex fluorine removing agent according to any one of claims 1 to 8, characterized by, The components of the rare earth composite fluorine removal agent include hydrated aluminum sulfate, aluminum chloride and rare earth oxides; wherein, the content of aluminum element, calculated as aluminum oxide, is 8%-20% in mass content; and the mass content of rare earth elements is 0.1%-5%.

10. The rare earth composite fluorine removal agent according to claim 9, wherein, The mass content of aluminum oxide is 10%-16%.

11. The rare earth composite fluorine removal agent according to claim 10, wherein, The mass content of aluminum oxide is 12.5%-16%.

12. The rare earth composite fluorine removal agent according to claim 11, wherein, The mass content of aluminum oxide is 14%-16%.

13. The use of the rare earth composite fluorine removal agent according to any one of claims 9-12 in fluorine removal.

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