CN114804179B - Method for recycling high-purity calcium fluoride from fluorine-containing waste residues - Google Patents
Method for recycling high-purity calcium fluoride from fluorine-containing waste residues Download PDFInfo
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- CN114804179B CN114804179B CN202210626239.4A CN202210626239A CN114804179B CN 114804179 B CN114804179 B CN 114804179B CN 202210626239 A CN202210626239 A CN 202210626239A CN 114804179 B CN114804179 B CN 114804179B
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- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 title claims abstract description 132
- 229910001634 calcium fluoride Inorganic materials 0.000 title claims abstract description 124
- 229910052731 fluorine Inorganic materials 0.000 title claims abstract description 77
- 239000011737 fluorine Substances 0.000 title claims abstract description 77
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 title claims abstract description 75
- 239000002699 waste material Substances 0.000 title claims abstract description 67
- 238000000034 method Methods 0.000 title claims abstract description 40
- 238000004064 recycling Methods 0.000 title abstract description 6
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims abstract description 68
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims abstract description 47
- 239000000292 calcium oxide Substances 0.000 claims abstract description 47
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims abstract description 47
- 229910000019 calcium carbonate Inorganic materials 0.000 claims abstract description 34
- 239000013078 crystal Substances 0.000 claims abstract description 24
- 239000007864 aqueous solution Substances 0.000 claims abstract description 19
- 238000011084 recovery Methods 0.000 claims abstract description 19
- 238000007667 floating Methods 0.000 claims abstract description 17
- 230000005764 inhibitory process Effects 0.000 claims abstract description 13
- 208000010392 Bone Fractures Diseases 0.000 claims abstract description 11
- 206010017076 Fracture Diseases 0.000 claims abstract description 11
- 239000002245 particle Substances 0.000 claims description 47
- 239000002105 nanoparticle Substances 0.000 claims description 25
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 24
- 239000003112 inhibitor Substances 0.000 claims description 15
- 238000010791 quenching Methods 0.000 claims description 15
- 230000000171 quenching effect Effects 0.000 claims description 15
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 14
- 238000000227 grinding Methods 0.000 claims description 10
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 9
- WRIDQFICGBMAFQ-UHFFFAOYSA-N (E)-8-Octadecenoic acid Natural products CCCCCCCCCC=CCCCCCCC(O)=O WRIDQFICGBMAFQ-UHFFFAOYSA-N 0.000 claims description 7
- LQJBNNIYVWPHFW-UHFFFAOYSA-N 20:1omega9c fatty acid Natural products CCCCCCCCCCC=CCCCCCCCC(O)=O LQJBNNIYVWPHFW-UHFFFAOYSA-N 0.000 claims description 7
- QSBYPNXLFMSGKH-UHFFFAOYSA-N 9-Heptadecensaeure Natural products CCCCCCCC=CCCCCCCCC(O)=O QSBYPNXLFMSGKH-UHFFFAOYSA-N 0.000 claims description 7
- 239000005642 Oleic acid Substances 0.000 claims description 7
- ZQPPMHVWECSIRJ-UHFFFAOYSA-N Oleic acid Natural products CCCCCCCCC=CCCCCCCCC(O)=O ZQPPMHVWECSIRJ-UHFFFAOYSA-N 0.000 claims description 7
- QXJSBBXBKPUZAA-UHFFFAOYSA-N isooleic acid Natural products CCCCCCCC=CCCCCCCCCC(O)=O QXJSBBXBKPUZAA-UHFFFAOYSA-N 0.000 claims description 7
- ZQPPMHVWECSIRJ-KTKRTIGZSA-N oleic acid Chemical compound CCCCCCCC\C=C/CCCCCCCC(O)=O ZQPPMHVWECSIRJ-KTKRTIGZSA-N 0.000 claims description 7
- 235000019353 potassium silicate Nutrition 0.000 claims description 7
- 238000001035 drying Methods 0.000 claims description 6
- 239000002351 wastewater Substances 0.000 claims description 6
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 5
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 5
- 239000004571 lime Substances 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 5
- GCLGEJMYGQKIIW-UHFFFAOYSA-H sodium hexametaphosphate Chemical compound [Na]OP1(=O)OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])OP(=O)(O[Na])O1 GCLGEJMYGQKIIW-UHFFFAOYSA-H 0.000 claims description 5
- 235000019982 sodium hexametaphosphate Nutrition 0.000 claims description 5
- 239000001577 tetrasodium phosphonato phosphate Substances 0.000 claims description 5
- 230000002401 inhibitory effect Effects 0.000 claims description 4
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 3
- 239000008267 milk Substances 0.000 claims description 3
- 210000004080 milk Anatomy 0.000 claims description 3
- 235000013336 milk Nutrition 0.000 claims description 3
- 238000006386 neutralization reaction Methods 0.000 claims description 3
- 238000001556 precipitation Methods 0.000 claims description 3
- 239000011734 sodium Substances 0.000 claims description 3
- 229910052708 sodium Inorganic materials 0.000 claims description 3
- 239000000725 suspension Substances 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 claims description 2
- 239000002994 raw material Substances 0.000 claims description 2
- 235000015424 sodium Nutrition 0.000 claims 1
- 230000008901 benefit Effects 0.000 abstract description 6
- 230000007613 environmental effect Effects 0.000 abstract description 3
- 239000000047 product Substances 0.000 description 64
- 238000005188 flotation Methods 0.000 description 21
- 239000010436 fluorite Substances 0.000 description 8
- 239000012535 impurity Substances 0.000 description 7
- 239000008367 deionised water Substances 0.000 description 6
- 229910021641 deionized water Inorganic materials 0.000 description 6
- 150000002889 oleic acids Chemical class 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- 238000001228 spectrum Methods 0.000 description 6
- 239000002893 slag Substances 0.000 description 5
- 229910004261 CaF 2 Inorganic materials 0.000 description 4
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 4
- 238000001354 calcination Methods 0.000 description 4
- 238000010304 firing Methods 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 238000000926 separation method Methods 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 239000006260 foam Substances 0.000 description 3
- 239000004115 Sodium Silicate Substances 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- -1 fluorine ions Chemical class 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000002386 leaching Methods 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 229910052573 porcelain Inorganic materials 0.000 description 2
- 230000006798 recombination Effects 0.000 description 2
- 238000005215 recombination Methods 0.000 description 2
- 229910052911 sodium silicate Inorganic materials 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- 241001391944 Commicarpus scandens Species 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 230000003321 amplification Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000003776 cleavage reaction Methods 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000002440 industrial waste Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 230000007017 scission Effects 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 238000010183 spectrum analysis Methods 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 230000004580 weight loss Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/20—Halides
- C01F11/22—Fluorides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03D—FLOTATION; DIFFERENTIAL SEDIMENTATION
- B03D1/00—Flotation
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Removal Of Specific Substances (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention provides a method for recycling high-purity calcium fluoride from fluorine-containing waste residues, wherein the fluorine-containing waste residues contain calcium fluoride and calcium carbonate, and the method comprises the following steps: s1, roasting the powdery fluorine-containing waste residues to enable calcium fluoride crystals to grow and enable calcium carbonate to be decomposed into calcium oxide, so that a roasting product is obtained; s2, sequentially performing calcium oxide floating inhibition treatment and calcium fluoride collection treatment on the roasting product in an aqueous solution to obtain a recovered product. In addition, before the calcium oxide floating inhibition treatment, the roasting product can be subjected to fracture treatment so as to break the inclusion structure of the roasting product. The invention can improve the recovery rate of calcium fluoride, improve the purity of the calcium fluoride in the recovered product, and has good economic and environmental benefits when recycling the fluorine-containing waste residue.
Description
Technical Field
The invention relates to the technical field of comprehensive treatment and utilization of industrial wastes, in particular to a method for recycling high-purity calcium fluoride from fluorine-containing waste residues.
Background
The fluorine chemical process can generate a large amount of fluorine-containing wastewater, and at present, an effective treatment method for the fluorine-containing wastewater is a neutralization precipitation method, and fluorine ions are stored in fluorine-containing waste residues in the form of calcium fluoride. However, because the fluoride-containing wastewater has carbonate and other impurity ions, calcium carbonate precipitation can be generated in the lime milk and fluoride-containing wastewater process, so that the purity of calcium fluoride in the fluoride-containing waste residue is low, and the calcium fluoride is difficult to directly use. Meanwhile, because the particles of the fluorine-containing waste residues are smaller, the fluorine ions have higher leaching risk in the long-term stacking process. In addition, fluorite (CaF 2) is a common additive in the industries of metallurgy, aluminum smelting and the like, is called as 'second rare earth', and has higher industrial value. Therefore, the recovery of the calcium fluoride in the fluorine-containing waste residues has higher economic and environmental benefits.
At present, the calcium fluoride is usually selected from fluorite ore by adopting a floatation mode. Therefore, recovery of calcium fluoride from the fluorine-containing waste residue by flotation is preferable from the viewpoint of saving equipment costs. However, in the actual recovery process, it was found that direct flotation of the fluorine-containing waste residue was difficult to achieve the recovery of calcium fluoride.
Therefore, there is a need to develop a method for recovering high-purity calcium fluoride from fluorine-containing waste residues, which not only can fully utilize precious fluorite resources in the fluorine-containing waste residues, but also can avoid leaching risks caused by long-term stacking, and has dual significance for recovery of fluorite resources in the fluorine-containing waste residues and environmental protection.
Disclosure of Invention
The invention mainly aims to provide a method for recycling high-purity calcium fluoride from fluorine-containing waste residues, and aims to solve the technical problems through a roasting-floatation process.
In order to achieve the above object, the present invention provides a method for recovering high purity calcium fluoride from a fluorine-containing waste residue containing calcium fluoride and calcium carbonate, comprising the steps of:
s1, roasting the powdery fluorine-containing waste residues to enable calcium fluoride crystals to grow and enable calcium carbonate to be decomposed into calcium oxide, so that a roasting product is obtained;
s2, sequentially performing calcium oxide floating inhibition treatment and calcium fluoride collection treatment on the roasting product in an aqueous solution to obtain a recovered product.
Further, the step S2 further includes: and before the calcium oxide floating inhibition treatment, carrying out fracture treatment on the roasting product to destroy the inclusion structure of the roasting product, so as to obtain the roasting product after the fracture treatment.
Further, the fracture treatment includes: and carrying out water quenching or grinding on the roasting product.
Further, the calcium fluoride in the fluorine-containing waste residue comprises: nano-sized calcium fluoride particles, or nano-sized calcium fluoride particles and micro-sized calcium fluoride floc consisting of a portion of nano-sized calcium fluoride particles;
the calcium carbonate in the fluorine-containing waste residue comprises: nano-sized calcium carbonate particles, or nano-sized calcium carbonate particles and micro-sized calcium carbonate floc consisting of a portion of nano-sized calcium carbonate particles.
Further, in the step S1, the preparation process of the powdered fluorine-containing waste residue includes: and (3) drying and grinding the fluorine-containing waste residues to ensure that the particle size of the fluorine-containing waste residues is not more than 150 mu m, so as to obtain the powdery fluorine-containing waste residues.
Further, the firing process includes: and (3) carrying out heat treatment on the powdery fluorine-containing waste residues at 600-900 ℃ for 0.5-5h.
Further, the calcium oxide floating inhibition treatment comprises: the calcined product is placed in the aqueous solution, and then an inhibitor that inhibits suspension of calcium oxide is added to the aqueous solution.
Further, the calcium fluoride recovery treatment includes: after the calcium oxide floating inhibition treatment, a collector for dissolving calcium oxide and suspending calcium fluoride is added into the aqueous solution.
Further, the inhibitor comprises one or more of sodium silicate, sodium hexametaphosphate and sodium humate;
the collector comprises a mixture of sulfuric acid and oleic acid.
Further, the mass ratio of the aqueous solution to the calcined product is 7 to 9:3-1;
During the calcium oxide floatation inhibiting treatment, the mass ratio of the inhibitor to the roasted product is 0.5-2.0g/kg;
during the calcium fluoride recovery treatment, the mass ratio of the collector to the calcined product is 0.3-1g/kg.
The technical principle of the invention comprises: in the high-temperature roasting (for example, 800 ℃) process, calcium carbonate is decomposed into calcium oxide, crystal recombination of calcium fluoride nano particles occurs under the high-temperature condition, and the calcium fluoride nano particles grow into micron-sized large particles, in the crystal recombination process of calcium fluoride, most of calcium oxide can be discharged out of the crystal structure of the calcium fluoride (impurity discharging growth behavior in the crystal growth process of calcium fluoride), and in the roasting process, preliminary separation of calcium fluoride and calcium oxide can be realized.
During the rapid growth of calcium fluoride crystals, it is inevitable that there will be a small portion of calcium oxide entrapped in the interstices of the large particle calcium fluoride. Because the inclusion structure is extremely easy to break under the action of stress, the inclusion structure of the roasting product can be destroyed in the water quenching or light grinding process, so that the calcium oxide can be better dissociated.
In the flotation process, the floatability of calcium oxide can be reduced through the action of an inhibitor, and the selective separation of calcium fluoride is realized under the action of a collector (sulfuric acid in modified oleic acid can dissolve part of calcium oxide, oleic acid foam wraps calcium fluoride and floats to the surface of a solution), so that the impurity amount carried by the floating calcium fluoride is reduced.
Compared with the prior art, the invention has at least the following advantages:
1. According to the invention, the difference of crystal formation of calcium fluoride and calcium carbonate in the roasting process in the fluoride-containing waste residue is utilized to convert nano-sized calcium fluoride into micron-sized large-particle crystals with complete crystal structures (the size is about 15-20 microns and calculated by the maximum length), and the calcium carbonate is decomposed into calcium oxide to still present nano-sized particles or flocculent clusters, so that the purpose of discharging the calcium carbonate from the calcium fluoride crystals is achieved; in addition, the micron-sized calcium fluoride particles meet the flotation conditions, so that high-purity calcium fluoride can be recovered through a flotation step in the following process, and the process benefit is improved.
2. The invention utilizes the stress effect in the water quenching or light grinding process to lead the calcium fluoride crystal coated with the calcium oxide to break at the joint surface of the calcium fluoride crystal and thoroughly expose the calcium oxide on the surface of the calcium fluoride crystal, thereby reducing the impurity amount carried by the calcium fluoride which is floated out later.
3. The invention utilizes the floatability difference generated by calcium fluoride crystal and calcium oxide agglomeration under the inhibitor and collector to selectively separate the calcium fluoride which is easy to float.
4. The invention has the advantages of low required roasting temperature, no need of special atmosphere and easy industrialized amplification. The flotation process has simple equipment, low equipment requirement and easy acquisition of inhibitor and collector, and can utilize the existing flotation equipment in fluorite industry to further reduce the cost of calcium fluoride separation.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.
FIG. 1 is an XRD spectrum of the fluorine-containing slag of example 1 and the recovered product (treated sample) of example 3;
FIG. 2 is an SEM spectrum of the fluorine-containing slag (original sample) of example 1;
FIG. 3 is an SEM spectrum of a calcined product (calcined sample) of example 3;
FIG. 4 is an SEM spectrum of the pretreatment product (sample after water quenching) of example 3;
Fig. 5 is an SEM spectrum of the recovered product (final product) in example 3.
The achievement of the object, functional features and advantages of the present invention will be further described with reference to the drawings in connection with the embodiments.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, based on the embodiments of the invention, which are apparent to those of ordinary skill in the art without inventive faculty, are intended to be within the scope of the invention.
It should be noted that all directional indicators (such as upper and lower … …) in the embodiments of the present invention are merely used to explain the relative positional relationship, movement conditions, etc. between the components in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indicator is changed accordingly.
Furthermore, descriptions such as those referred to as "first," "second," and the like, are provided for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implying an order of magnitude of the indicated technical features in the present disclosure. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature.
Moreover, the technical solutions of the embodiments of the present invention may be combined with each other, but it is necessary to be based on the fact that those skilled in the art can implement the embodiments, and when the technical solutions are contradictory or cannot be implemented, it should be considered that the combination of the technical solutions does not exist, and is not within the scope of protection claimed by the present invention.
The inventors have found through a great deal of research that the fluorine-containing waste residue according to the present invention contains calcium fluoride and calcium carbonate, and in general, the calcium fluoride in the fluorine-containing waste residue includes: nano-sized calcium fluoride particles, or nano-sized calcium fluoride particles and micro-sized calcium fluoride floc consisting of a portion of nano-sized calcium fluoride particles; i.e. calcium fluoride, generally presents particles of nanometric scale, some of which may also form flocculent clusters of micrometric scale.
The calcium carbonate in the fluorine-containing waste residue comprises: nano-sized calcium carbonate particles, or nano-sized calcium carbonate particles and micro-sized calcium carbonate floc consisting of a portion of nano-sized calcium carbonate particles; i.e. calcium carbonate, generally presents particles of nanometric scale, some of which may also form flocculent clusters of micrometric scale.
The particle size of the calcium fluoride and the calcium carbonate in the fluorine-containing waste residue is about 100 nanometers (0.1 micrometer), the lower limit of the particle size of the conventional fluorite flotation cannot be reached, and the micron-sized flocculent clusters are easily dispersed into nano particles (the micron-sized clusters can be subjected to flotation) due to the collision between particles or between particles and a flotation machine in the flotation process, so that the purpose of recovering the calcium fluoride is difficult to achieve by directly floating the fluorine-containing waste residue.
Based on this, the invention provides a method for recovering high purity calcium fluoride from fluorine-containing waste residues, comprising the steps of:
S1, roasting the powdery fluorine-containing waste residues to enable calcium fluoride crystals to grow and enable calcium carbonate to be decomposed into calcium oxide, so that a roasting product is obtained.
It should be appreciated that the fluorine-containing waste residues may be: the industrial fluorine-containing wastewater is taken as a raw material, and the precipitate is produced after neutralization by lime or lime milk.
After the fluorine-containing waste residue is obtained, the fluorine-containing waste residue can be grinded in advance so that the particle size of the fluorine-containing waste residue is not more than 150 μm, and the fluorine-containing waste residue in powder form is obtained.
In order to make the powdery fluorine-containing slag in a dry state, the fluorine-containing slag may be further subjected to a drying treatment before being ground.
It is also understood that in this step, the calcination treatment may cause the nano-sized calcium fluoride particles or flocs to grow into micro-sized calcium fluoride particles during the calcination process, while the calcium carbonate is decomposed into calcium oxide and is discharged out of the calcium fluoride crystals.
The roasting treatment can be performed in a muffle furnace, and specifically can comprise: and (3) carrying out heat treatment on the powdery fluorine-containing waste residues at 600-900 ℃ for 0.5-5h. Preferably, the fluorine-containing slag in powder form may be heat-treated at 800 ℃ for 2 hours.
S2, sequentially performing calcium oxide floating inhibition treatment and calcium fluoride collection treatment on the roasting product in an aqueous solution to obtain a recovered product, namely recovered calcium fluoride. The recovered calcium fluoride can be used as ceramic-grade fluorite powder for the production of chemical products such as ceramics, glass and the like.
Before the calcium oxide floating inhibition treatment is performed on the roasting product, the roasting product can be subjected to fracture treatment to break the inclusion structure of the roasting product, so that the roasting product after the fracture treatment, namely a pretreatment product, is obtained.
It is to be understood that during the rapid growth of calcium fluoride crystals, there is inevitably a small portion of calcium oxide entrapped in the interstices of the large-particle calcium fluoride. Thus, the cleavage treatment is to break the inclusion structure of the calcined product, i.e., break the inclusion of large particles of calcium fluoride to calcium oxide.
The fracture treatment mode can comprise the following steps: and carrying out water quenching or grinding on the roasting product. Specifically, the water quenching can be water quenching, wherein the water quenching means: the roasting product which is just roasted and is not cooled is directly soaked in water at normal temperature or room temperature so as to destroy the entrapment of the large-particle calcium fluoride on the calcium oxide. In addition, the grinding means: the entrapment of the large particle calcium fluoride to the calcium oxide is destroyed by mild grinding (i.e., with less grinding force).
As an explanation of the calcium oxide floating suppression treatment and the calcium fluoride collection treatment:
The calcium oxide flotation inhibiting treatment and the calcium fluoride collection treatment may be performed in a flotation machine, i.e. the aqueous solution is contained in a flotation machine.
The calcium oxide floating treatment is to reduce the floatability of calcium oxide, and may include: placing the calcined product or the pretreatment in the aqueous solution, and then adding an inhibitor for inhibiting calcium oxide suspension to the aqueous solution.
The aqueous solution can be deionized water or other conventional water bodies, and the mass ratio of the aqueous solution to the roasting product (or the pretreatment dry basis) only needs to meet the conventional flotation requirements. As an example, the mass ratio of the aqueous solution to the calcined product (or pretreatment dried basis) may be 7-9:3-1.
In the calcium oxide floating inhibition treatment process, the ratio of the added mass of the inhibitor to the mass of the roasting product (or the dry matter mass of the pretreatment) is 0.5-2.0g/kg.
The inhibitor comprises one or more of sodium silicate, sodium hexametaphosphate and sodium humate.
The calcium fluoride collection treatment is used for realizing the selective separation of calcium fluoride and reducing the impurity content carried by the floated calcium fluoride. The calcium fluoride recovery process may include: after the calcium oxide floating inhibition treatment, a collector for dissolving calcium oxide and suspending calcium fluoride is added into the aqueous solution.
During the calcium fluoride collecting treatment, the ratio of the adding mass of the collecting agent to the mass of the roasting product (or the dry mass of the pretreatment) is 0.3-1g/kg.
The collector may comprise a mixture of sulfuric acid and oleic acid, the molar ratio of sulfuric acid to oleic acid may be in the range of 0.1-0.4:1.
To facilitate a detailed understanding of the invention by those skilled in the art, reference will now be made to the accompanying drawings, in which:
Example 1
Preparing powdery fluorine-containing waste residues and measuring the fluorine-containing waste residues:
Taking the fluorine-containing waste residue after drying and dewatering in a certain factory, and grinding the fluorine-containing waste residue to be used to be less than 150 mu m to obtain powdery fluorine-containing waste residue; XRD measurement, SEM spectrum analysis and content analysis are carried out on the powder fluorine-containing waste residue to be used.
Referring to fig. 1, as determined by XRD: the main substances in the fluorine-containing waste residues are CaF 2 and CaCO 3.
Referring to fig. 2, SEM spectra show that: in the fluorine-containing waste residue, calcium fluoride and calcium carbonate are in nano-sized particles and flocculent clusters.
In addition, the content of CaF 2 in the fluorine-containing waste residue is measured according to national standard 'determination of fluorite calcium fluoride content' GB/T5195.1-2017; analyzing a weight loss curve of the roasting process of the fluorine-containing waste residues by using a synchronous thermal analyzer (TG-DSC), and calculating the content of CaCO 3; the types and contents of other impurity elements were semi-quantitatively analyzed mainly by XRF.
The result shows that in the fluorine-containing waste residue, the content of CaF 2 is 63.38%, the content of CaCO 3 is 25.5%, and other main impurity elements are Cl, na, S, mg, al, si, fe.
Example 2
The porcelain boat containing 1kg of the powdery fluorine-containing waste residue (derived from example 1) was put into a muffle furnace and baked at 800 ℃ for 2 hours to obtain a baked product.
Placing the cooled roasting product into a flotation machine containing deionized water (the mass ratio of the deionized water to the roasting product is 7.5:2.5); then adding water glass as an inhibitor (the mass ratio of the water glass to the baked product is 1.0 g/kg), and fully stirring for about 20min to fully mix the fluorine-containing waste residue with the water glass; and adding modified oleic acid serving as a collector (the molar ratio of sulfuric acid to oleic acid is 0.2:1, and the mass ratio of modified oleic acid to calcined product is 0.6 g/kg), stirring and mixing for 10min, separating out the upper layer of particles with foam through a scraper of a flotation machine, and drying the separated particles to obtain a recovered product (calcium fluoride product).
The recovery rate of calcium fluoride was determined to be 90% (i.e., the mass ratio of calcium fluoride in the recovered product to calcium fluoride in the fluorine-containing waste residue), and the content of calcium fluoride in the recovered product was determined to be 85%.
Example 3
In this example, the water quenching process was increased compared to example 2. The method specifically comprises the following steps:
The porcelain boat containing 1kg of the powdery fluorine-containing waste residue (derived from example 1) was put into a muffle furnace and baked at 800 ℃ for 2 hours to obtain a baked product.
And after the roasting is finished, immediately soaking the uncooled roasting product in deionized water at normal temperature for 1min to perform water quenching, so as to obtain a pretreatment product.
Placing the pretreatment into a flotation machine containing deionized water (the ratio of the mass of the deionized water to the mass of the pretreatment is 7.5:2.5); then adding water glass as an inhibitor (the ratio of the mass of the water glass to the mass of the pretreatment matter is 1.0 g/kg), and fully stirring for about 20min to fully mix the fluorine-containing waste residues with the water glass; and adding modified oleic acid serving as a collector (the molar ratio of sulfuric acid to oleic acid is 0.2:1, and the ratio of the mass of the modified oleic acid to the mass of the pretreatment matter is 0.6 g/kg), stirring and mixing for 10min, separating out the upper layer of particles with foam through a scraper of a flotation machine, and drying the separated particles to obtain a recovered product (calcium fluoride product).
The measurement shows that the recovery rate of calcium fluoride is 88%, and the content of calcium fluoride in the recovered product is 90%, which indicates that the water quenching can improve the purity of calcium fluoride in the recovered product without obviously reducing the recovery rate of calcium fluoride.
Referring to fig. 1, it can be seen from the XRD pattern that the peak of calcium carbonate in the recovered product is almost absent, and it can be considered that calcium carbonate is almost absent in the recovered product.
Further, referring to fig. 3, SEM images show that the calcined product formed large particle crystals (about 15-20 microns in size, calculated as maximum length) on the order of microns and exhibited a distinct crystal appearance.
Referring to fig. 4, after water quenching, the large particle crystals in the pretreatment disintegrated into several pieces, and the fracture surface appeared, but still exhibited a distinct crystal appearance, with the dimensions after water quenching being about 2-10 microns (calculated as maximum length).
Referring to fig. 5, it can be seen that the surface of the recovered product is smoother, and the purity of calcium fluoride is greatly improved.
Example 4
In this example, the firing temperature was 700℃as compared with example 3, and the other operations were the same as in example 3, to obtain a recovered product.
In this example, the recovery rate of calcium fluoride was 74%, and the content of calcium fluoride in the recovered product was 82%. Thus, lowering the firing temperature affects the growth of calcium fluoride crystals.
Example 5
In this example, the calcination time was 5 hours as compared with example 3, and the other operations were the same as in example 3, to obtain a recovered product.
In this example, the recovery rate of calcium fluoride was 88%, and the content of calcium fluoride in the recovered product was 90%. Thus, extending the firing time does not further increase the product conversion.
Example 6
In this example, the calcination time was 0.5h as compared to example 3, and the recovered product was obtained in the same manner as in example 3.
In this example, the recovery rate of calcium fluoride was 81%, and the content of calcium fluoride in the recovered product was 87%.
Example 7
In this example, sodium hexametaphosphate was used as an inhibitor in the flotation process as compared to example 3, and the other operations were the same as in example 3 to obtain a recovered product.
In this example, the recovery rate of calcium fluoride was 89%, and the content of calcium fluoride in the recovered product was 89%. It is explained that sodium hexametaphosphate is also suitable for use in the present invention.
Example 8
In this example, the ratio of the mass of modified oleic acid to the mass of the dry matter of the pretreatment in the flotation process was changed to 1g/kg as compared with example 3, and the recovered product was obtained in the same manner as in example 3.
In this example, the recovery rate of calcium fluoride was 87%, and the content of calcium fluoride in the recovered product was 86%.
In the above technical solution of the present invention, the above is only a preferred embodiment of the present invention, and therefore, the patent scope of the present invention is not limited thereto, and all the equivalent structural changes made by the description of the present invention and the content of the accompanying drawings or the direct/indirect application in other related technical fields are included in the patent protection scope of the present invention.
Claims (5)
1. A method for recovering high-purity calcium fluoride from fluorine-containing waste residues, wherein the fluorine-containing waste residues contain calcium fluoride and calcium carbonate,
The fluorine-containing waste residues are as follows: taking industrial fluorine-containing wastewater as a raw material, and carrying out precipitation generated after lime or lime milk neutralization;
The calcium fluoride in the fluorine-containing waste residue comprises: nano-sized calcium fluoride particles, or nano-sized calcium fluoride particles and micro-sized calcium fluoride floc consisting of a portion of nano-sized calcium fluoride particles;
The calcium carbonate in the fluorine-containing waste residue comprises: nano-sized calcium carbonate particles, or nano-sized calcium carbonate particles and micro-sized calcium carbonate floc consisting of a portion of nano-sized calcium carbonate particles;
The method comprises the steps of:
s1, roasting the powdery fluorine-containing waste residues to enable calcium fluoride crystals to grow and enable calcium carbonate to be decomposed into calcium oxide, so that a roasting product is obtained;
The preparation process of the powdery fluorine-containing waste residue comprises the following steps: drying and grinding the fluorine-containing waste residues to ensure that the particle size of the fluorine-containing waste residues is not more than 150 mu m, so as to obtain powdery fluorine-containing waste residues;
The baking treatment includes: heat-treating the powdery fluorine-containing waste residue at 600-800 ℃ for 0.5-5h;
S2, sequentially performing calcium oxide floating inhibition treatment and calcium fluoride collection treatment on the roasting product in an aqueous solution to obtain a recovered product;
before the calcium oxide floating inhibition treatment, carrying out fracture treatment on the roasting product to destroy the inclusion structure of the roasting product, so as to obtain the roasting product after the fracture treatment;
the fracture treatment includes: carrying out water quenching on the roasting product;
The water quenching means: the roasting product which is just roasted and is not cooled is directly soaked in water at normal temperature or room temperature so as to destroy the inclusion of large-particle calcium fluoride on calcium oxide.
2. The method for recovering high purity calcium fluoride according to claim 1, wherein the calcium oxide float-suppressing treatment comprises: the calcined product is placed in the aqueous solution, and then an inhibitor that inhibits suspension of calcium oxide is added to the aqueous solution.
3. The method for recovering high purity calcium fluoride according to claim 2, wherein the calcium fluoride recovery process comprises: after the calcium oxide floating inhibition treatment, a collector for dissolving calcium oxide and suspending calcium fluoride is added into the aqueous solution.
4. The method of recovering high purity calcium fluoride of claim 3, wherein the inhibitor comprises one or more of water glass, sodium hexametaphosphate, and sodium humate;
the collector comprises a mixture of sulfuric acid and oleic acid.
5. A method for recovering high purity calcium fluoride according to claim 3 wherein the mass ratio of the aqueous solution to the calcined product is from 7 to 9:3-1;
During the calcium oxide floatation inhibiting treatment, the mass ratio of the inhibitor to the roasted product is 0.5-2.0g/kg;
during the calcium fluoride recovery treatment, the mass ratio of the collector to the calcined product is 0.3-1g/kg.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102921551A (en) * | 2011-12-06 | 2013-02-13 | 龙泉市砩矿有限责任公司 | Fluorite mineral flotation method |
| CN104694736A (en) * | 2015-03-23 | 2015-06-10 | 东北大学 | Calcium roasting floatation separation method for bastnaesite |
| CN109225606A (en) * | 2018-09-11 | 2019-01-18 | 洛阳冀能新材料有限公司 | A kind of separation system and sorting process of carbonate-type fluorite ore |
| CN112791847A (en) * | 2020-12-15 | 2021-05-14 | 东北大学 | Method for separating and recovering iron, rare earth and fluorine from rare earth-containing iron dressing tailings |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102921551A (en) * | 2011-12-06 | 2013-02-13 | 龙泉市砩矿有限责任公司 | Fluorite mineral flotation method |
| CN104694736A (en) * | 2015-03-23 | 2015-06-10 | 东北大学 | Calcium roasting floatation separation method for bastnaesite |
| CN109225606A (en) * | 2018-09-11 | 2019-01-18 | 洛阳冀能新材料有限公司 | A kind of separation system and sorting process of carbonate-type fluorite ore |
| CN112791847A (en) * | 2020-12-15 | 2021-05-14 | 东北大学 | Method for separating and recovering iron, rare earth and fluorine from rare earth-containing iron dressing tailings |
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