CN-121990661-A - Lanthanum enhanced defluorinating agent and production and recovery methods and application thereof

CN121990661ACN 121990661 ACN121990661 ACN 121990661ACN-121990661-A

Abstract

The invention discloses a lanthanum enhanced defluorinating agent, a production and recovery method and application thereof, belonging to the technical field of industrial wastewater treatment, wherein the lanthanum enhanced defluorinating agent takes cellulose fiber as an adhesive and alkaline earth metal salt inorganic powder as a basic adsorption component, and a compound of rare earth element lanthanum is additionally added as an active ingredient; the method comprises three steps of mixing and stirring, molding and drying, wherein fluorine-containing wastewater is contacted with the fluorine-removing agent, alkaline earth metal reacts with fluorine to generate insoluble fluoride, lanthanum compound synchronously forms stable fluorine-lanthanum complex, the concentration of fluorine ions is reduced to below 5mg under the dual action, the molded body absorbing fluorine is separated during fluorine recovery, and the cellulose is removed by drying and sintering to obtain a high-purity alkaline earth metal fluoride and lanthanum oxide mixed product, so that the fluorine and rare earth resources are cooperatively recovered.

Inventors

ZHANG ZHENGHANG
WANG ZHONGMIN
FEI XIAOXIN
YANG JIACHONG
LIU QINGGUANG
ZHANG YIXUAN

Assignees

中冶华天工程技术有限公司

Dates

Publication Date: 20260508
Application Date: 20251231

Claims (10)

1. A lanthanum enhanced fluorine removing agent is characterized by being prepared by mixing, forming and drying 0.24-11.4 parts of adhesive, 9.7-40 parts of inorganic powder and 0.06-0.8 part of active ingredient according to the weight part ratio, wherein the adhesive is cellulose fiber, the cellulose fiber is one or more of cellulose nanofiber CNF with the beam diameter of less than 0.1 mu m, cellulose microfiber CMF with the beam diameter of 0.1-10 mu m and conventional cellulose fiber CF with the beam diameter of 10-120 mu m, the inorganic powder is alkaline earth metal salt inorganic powder, the alkaline earth metal salt inorganic powder is one or more of magnesium salt, calcium salt, strontium salt, barium salt, magnesium hydroxide, calcium phosphate and calcium carbonate, the active ingredient is a compound of lanthanum of rare earth element, the compound of lanthanum rare earth element La is lanthanum chloride 3 , lanthanum nitrate La (one or more of NO 3 ) 3 and lanthanum oxide 2 O 3 , and the fluorine ratio of the compound of rare earth element La is 5% -5% of the fluorine removing agent.
2. A method for producing the lanthanum enhanced defluorinating agent according to claim 1, which comprises the following specific steps: step one, mixing and stirring engineering: S11, mixing 0.24-11.4 parts of adhesive cellulose fiber, 9.7-40 parts of inorganic powder alkaline earth metal salt inorganic powder, 0.06-0.8 part of active ingredient rare earth element lanthanum compound and 5-28 parts of water according to the weight part; s12, dissolving a rare earth element lanthanum compound in warm water at 50-60 ℃ to accelerate dissolution, avoiding caking, premixing the compound with alkaline earth metal salt inorganic powder for 10-15 minutes to form a premix, adding cellulose fibers, and stirring for 20-30 minutes by adopting a stirrer, a kneader or a three-roll machine to form a uniform pasty mixture; A second step of molding engineering, namely adopting a die molding, extrusion molding or paper making molding mode to prepare the uniform pasty mixture obtained in the first step into a cylindrical, film-shaped or block-shaped molded body, wherein the extrusion molding adopts gold with the aperture of 5-10mm, and the length of the molded body is controlled to be 5-30mm; And thirdly, drying the molded body prepared in the second step in a vacuum or normal pressure environment at 40-160 ℃ under the vacuum degree of 10 2 -10 5 Pa, and controlling the residual moisture content of the molded body to be 5% -15% after drying so as to ensure the water permeability and the structural strength and avoid the decomposition of lanthanum compounds caused by high temperature.
3. The method for producing a lanthanum enhanced fluorine removing agent according to claim 2, wherein in S12, if a dry conventional cellulose fiber CF is used, water is added to the mixture to a state of "no sticking to the hand by finger, no breaking by rubbing in a strip-like form", and if a commercially available cellulose nanofiber CNF or cellulose microfiber CMF containing moisture is used, the water content is adjusted according to the viscosity of the mixture.
4. The method for producing a lanthanum enhanced fluorine scavenger according to claim 2, wherein the drying temperature in the third step is 60-120 ℃ and the vacuum degree is 10 3 -10 4 Pa.
5. The application of the lanthanum enhanced fluorine removal agent in fluorine-containing wastewater treatment is characterized in that fluorine-containing wastewater with the fluorine ion concentration of 10-1500ppm is contacted with the lanthanum enhanced fluorine removal agent, the fluorine-containing wastewater is metal manufacturing wastewater, semiconductor pickling wastewater, refrigerant decomposition wastewater or fluororesin production wastewater, the fluorine-containing wastewater circularly flows through a lanthanum enhanced fluorine removal agent bed layer or the lanthanum enhanced fluorine removal agent to be immersed in the fluorine-containing wastewater, alkaline earth metal in the lanthanum enhanced fluorine removal agent and fluorine ions are subjected to chemical reaction to generate insoluble alkaline earth metal fluoride in the contact process, meanwhile, a compound of active ingredient lanthanum and the fluorine ions form a stable fluorine lanthanum complex, the fluorine lanthanum complex is LaF 3 , the dual action improves the fluorine removal efficiency, the reaction temperature is 20-40 ℃, the reaction time is 20-100 minutes, and finally the fluorine ion concentration in the fluorine-containing wastewater is reduced to below 5 mg/L.
6. A method for recovering a lanthanum enhanced fluorine scavenger according to claim 1, comprising the steps of: S1, solid-liquid separation, namely filtering or naturally settling and separating a lanthanum enhanced fluorine removing agent subjected to fluorine adsorption from treated water reaching the standard to obtain a formed body subjected to fluorine adsorption, wherein the formed body subjected to fluorine adsorption contains insoluble alkaline earth metal fluoride and lanthanum fluoride complex; s2, drying pretreatment, namely placing the separated formed body subjected to fluorine adsorption in an environment of 100-120 ℃ for drying for 20-28 hours, and removing water attached to the surface of the formed body; S3, sintering and recycling, namely placing the dried formed body in an electric furnace, and sintering for 1.5-2.5 hours at the temperature of 400-450 ℃ to completely decompose and remove cellulose fibers in the formed body, so as to obtain a mixed product containing high-purity alkaline earth metal fluoride and lanthanum fluoride LaF 3 , wherein the purity of lanthanum fluoride in the mixed product is more than or equal to 97%, and the mixed product can be used as a fluorite substitute material, an optical glass raw material or a rare earth functional material raw material, so that the synergistic recycling of fluorine and rare earth elements is realized.
7. The production method of the lanthanum enhanced fluorine removing agent according to claim 2, wherein in the second step, 80-120 mesh wire is adopted in the papermaking and forming process, the thickness of the formed film-shaped adsorbent is 0.5-2mm, permeable holes with the aperture of 10-50 μm are uniformly distributed on the surface of the film, the distribution uniformity deviation of lanthanum compounds in the film is less than or equal to 3%, and the stable adsorption performance is ensured.
8. The application of the lanthanum enhanced fluorine removing agent in fluorine-containing wastewater treatment according to claim 5, wherein when the pH value of the fluorine-containing wastewater is 2-5, alkaline earth metal salt inorganic powder in the lanthanum enhanced fluorine removing agent can synchronously adjust the pH value of the wastewater to 6-8 without adding an acid-base regulator, and in the pH range, the adsorption selectivity of a rare earth element lanthanum compound on fluorine ions is improved by 10% -15%, the capability of resisting other anions is enhanced, and the other anions are Cl - and/or SO 4 2- .
9. The method for recycling the lanthanum enhanced fluorine removing agent according to claim 6, wherein the temperature rising rate in the firing recycling process is 5-10 ℃ per minute, cracking of a formed body caused by too high temperature rising is avoided, after firing, no cellulose residual peak exists in a mixed product, the strength of lanthanum fluoride characteristic peaks is stable through X-ray diffraction analysis, the quality of the recycled product is ensured, high-purity alkaline earth metal fluoride and lanthanum fluoride are leached through nitric acid solution with the concentration of 0.5-1mol/L, and the stepwise recycling of the high-purity alkaline earth metal fluoride and lanthanum fluoride is realized through the solubility difference of the high-purity alkaline earth metal fluoride and the lanthanum fluoride.
10. The lanthanum enhanced fluorine removal agent according to claim 1, wherein lanthanum chloride LaCl 3 is lanthanum chloride hexahydrate LaCl 3 ・6H 2 O, lanthanum nitrate La (NO 3 ) 3 is lanthanum nitrate heptahydrate La (NO 3 ) 3 ・7H 2 O), which has good water solubility and strong compatibility with other raw materials, and is not easy to generate volatile impurities in the drying process, so that the preparation stability and adsorption efficiency of the fluorine removal agent can be further improved.

Description

Lanthanum enhanced defluorinating agent and production and recovery methods and application thereof Technical Field The application relates to the technical field of industrial wastewater treatment, in particular to a lanthanum enhanced fluorine removal agent and a production and recovery method and application thereof. Background A large amount of fluorine-containing wastewater is generated in the production process of the industries of semiconductors, electronics, electroplating, glass ceramics and the like, if the wastewater is directly discharged, the wastewater seriously pollutes the water environment, and threats the natural environment and the human health, so that the wastewater is required to reach the discharge standard through defluorination treatment. In recent years, the concentration of fluoride ions in industrial wastewater discharged from factories should be less than 10mg/L. In the current mainstream industrial wastewater defluorination technology, the adsorption scheme using alkaline earth metal salt inorganic powder (such as calcium hydroxide and calcium carbonate) as a core is widely applied. The fluoride is removed by generating insoluble fluoride through chemical reaction with fluoride ions, but the powder has the problem of difficult solid-liquid separation, namely, the generated fine fluoride has small crystallization specific gravity difference, filtering is needed to be carried out by relying on a filter cloth with a fine pore diameter or polymer coagulant is added for assisting sedimentation, thus not only increasing the treatment cost, but also easily causing filter cloth blockage and low treatment efficiency, and the fluoride is difficult to recycle after coagulant impurities are mixed in the fluoride. In order to improve the solid phase formability and the separation efficiency, a part of technologies introduce adhesives such as cellulose fibers and the like to form inorganic powder, but the pure cellulose-alkaline earth metal salt composite adsorbent still has the defects of limited adsorption capacity and poor selectivity, and when facing complex wastewater containing interfering anions such as Cl -、SO42- and the like, the fluorine removal efficiency is easily affected, and the concentration of fluorine ions is difficult to be stably reduced to a low level. In addition, the rare earth element lanthanum has strong complexing capability on fluoride ions and is used for improving the fluoride removal performance, but the existing lanthanum-containing fluoride removal technology is mainly used for directly loading lanthanum on a polymer or rare earth carrier, so that the problems of high raw material cost and fluctuation in adsorption performance caused by uneven lanthanum dispersion are solved, the lanthanum-containing fluoride removal technology is not effectively combined with a cellulose-alkaline earth metal salt system, and the requirements of low cost, easiness in forming, high selectivity for fluoride removal and fluoride-rare earth collaborative recovery cannot be met at the same time. Therefore, a novel defluorinating agent integrating an adhesive, alkaline earth metal salt inorganic powder and rare earth lanthanum active ingredients can be developed to solve the pain point in the prior art. Disclosure of Invention The invention provides a lanthanum enhanced fluorine removing agent, and a production and recovery method and application thereof, and solves the technical problems of low fluorine removing agent treatment efficiency, high recovery difficulty and the like in the prior art. The lanthanum-enhanced fluorine removing agent is prepared by mixing, forming and drying 0.24-11.4 parts by weight of adhesive, 9.7-40 parts by weight of inorganic powder and 0.06-0.8 part by weight of active ingredient, wherein the adhesive is cellulose fiber, the cellulose fiber is one or more of cellulose nanofiber CNF with the bundle diameter of less than 0.1 mu m and cellulose microfiber CMF with the bundle diameter of 0.1-10 mu m and conventional cellulose fiber CF with the bundle diameter of 10-120 mu m, the inorganic powder is alkaline earth metal salt inorganic powder, the alkaline earth metal salt inorganic powder is one or more of magnesium salt, calcium salt, strontium salt, barium salt, magnesium hydroxide, calcium phosphate and calcium carbonate, the active ingredient is a compound of lanthanum which is lanthanum, the compound of lanthanum chloride LaCl 24 and lanthanum nitrate (one or more of lanthanum oxide 2O3) accounts for 5-5% by weight of lanthanum-enhanced lanthanum-free compound. The production method of the lanthanum enhanced fluorine removing agent comprises the following specific steps: step one, mixing and stirring engineering: S11, mixing 0.24-11.4 parts of adhesive cellulose fiber, 9.7-40 parts of inorganic powder alkaline earth metal salt inorganic powder, 0.06-0.8 part of active ingredient rare earth element lanthanum compound and 5-28 parts of water according t