CN117305630A - Method for extracting valuable rare earth from bastnaesite at low cost - Google Patents
Method for extracting valuable rare earth from bastnaesite at low cost Download PDFInfo
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- CN117305630A CN117305630A CN202311192879.XA CN202311192879A CN117305630A CN 117305630 A CN117305630 A CN 117305630A CN 202311192879 A CN202311192879 A CN 202311192879A CN 117305630 A CN117305630 A CN 117305630A
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- 229910052761 rare earth metal Inorganic materials 0.000 title claims abstract description 117
- 150000002910 rare earth metals Chemical class 0.000 title claims abstract description 73
- 238000000034 method Methods 0.000 title claims abstract description 46
- 238000002386 leaching Methods 0.000 claims abstract description 79
- -1 rare earth sulfate Chemical class 0.000 claims abstract description 47
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 46
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims abstract description 36
- 239000000706 filtrate Substances 0.000 claims abstract description 36
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 32
- 239000007788 liquid Substances 0.000 claims abstract description 24
- 239000002893 slag Substances 0.000 claims abstract description 23
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 claims abstract description 21
- 239000001110 calcium chloride Substances 0.000 claims abstract description 21
- 229910001628 calcium chloride Inorganic materials 0.000 claims abstract description 21
- 238000001914 filtration Methods 0.000 claims abstract description 19
- QCCDYNYSHILRDG-UHFFFAOYSA-K cerium(3+);trifluoride Chemical compound [F-].[F-].[F-].[Ce+3] QCCDYNYSHILRDG-UHFFFAOYSA-K 0.000 claims abstract description 15
- 239000002253 acid Substances 0.000 claims abstract description 10
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 claims abstract description 10
- 239000000047 product Substances 0.000 claims abstract description 10
- 239000012141 concentrate Substances 0.000 claims abstract description 9
- 230000001590 oxidative effect Effects 0.000 claims abstract description 9
- 238000006243 chemical reaction Methods 0.000 claims description 43
- 238000000605 extraction Methods 0.000 claims description 24
- 238000003756 stirring Methods 0.000 claims description 17
- 238000002156 mixing Methods 0.000 claims description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- 238000000926 separation method Methods 0.000 claims description 10
- 239000002699 waste material Substances 0.000 claims description 7
- 239000011575 calcium Substances 0.000 claims description 5
- 239000012535 impurity Substances 0.000 claims description 5
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 4
- 229910052791 calcium Inorganic materials 0.000 claims description 4
- 238000003723 Smelting Methods 0.000 claims description 3
- 239000000292 calcium oxide Substances 0.000 claims description 3
- 229910000420 cerium oxide Inorganic materials 0.000 claims description 3
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 claims description 3
- 239000000344 soap Substances 0.000 claims description 2
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims 2
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims 2
- 230000002378 acidificating effect Effects 0.000 claims 1
- 239000000203 mixture Substances 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 abstract description 12
- 230000009466 transformation Effects 0.000 abstract description 7
- 238000001556 precipitation Methods 0.000 abstract description 5
- 238000004065 wastewater treatment Methods 0.000 abstract description 5
- 239000006227 byproduct Substances 0.000 abstract description 2
- 230000009467 reduction Effects 0.000 abstract description 2
- 239000000243 solution Substances 0.000 description 45
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 22
- 229910052731 fluorine Inorganic materials 0.000 description 22
- 239000011737 fluorine Substances 0.000 description 22
- 230000008569 process Effects 0.000 description 14
- 229910052684 Cerium Inorganic materials 0.000 description 13
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 13
- 238000005406 washing Methods 0.000 description 11
- 239000002351 wastewater Substances 0.000 description 8
- 239000002994 raw material Substances 0.000 description 6
- 239000000460 chlorine Substances 0.000 description 5
- 229910052801 chlorine Inorganic materials 0.000 description 5
- 239000002244 precipitate Substances 0.000 description 5
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000002585 base Substances 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- 239000002912 waste gas Substances 0.000 description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 239000004566 building material Substances 0.000 description 2
- 239000004568 cement Substances 0.000 description 2
- 239000003638 chemical reducing agent Substances 0.000 description 2
- 229910001610 cryolite Inorganic materials 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 229910052602 gypsum Inorganic materials 0.000 description 2
- 239000010440 gypsum Substances 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 229910001404 rare earth metal oxide Inorganic materials 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000006228 supernatant Substances 0.000 description 2
- ZSLUVFAKFWKJRC-IGMARMGPSA-N 232Th Chemical compound [232Th] ZSLUVFAKFWKJRC-IGMARMGPSA-N 0.000 description 1
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 229910052776 Thorium Inorganic materials 0.000 description 1
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- IKNAJTLCCWPIQD-UHFFFAOYSA-K cerium(3+);lanthanum(3+);neodymium(3+);oxygen(2-);phosphate Chemical compound [O-2].[La+3].[Ce+3].[Nd+3].[O-]P([O-])([O-])=O IKNAJTLCCWPIQD-UHFFFAOYSA-K 0.000 description 1
- 230000000536 complexating effect Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 150000004673 fluoride salts Chemical class 0.000 description 1
- 230000008570 general process Effects 0.000 description 1
- 238000009854 hydrometallurgy Methods 0.000 description 1
- 239000003350 kerosene Substances 0.000 description 1
- 150000007522 mineralic acids Chemical class 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910052590 monazite Inorganic materials 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000004537 pulping Methods 0.000 description 1
- 238000005185 salting out Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B59/00—Obtaining rare earth metals
-
- 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
- C01F11/46—Sulfates
-
- 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
- C01F17/00—Compounds of rare earth metals
- C01F17/20—Compounds containing only rare earth metals as the metal element
- C01F17/253—Halides
- C01F17/265—Fluorides
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
- C22B3/04—Extraction of metal compounds from ores or concentrates by wet processes by leaching
- C22B3/06—Extraction of metal compounds from ores or concentrates by wet processes by leaching in inorganic acid solutions, e.g. with acids generated in situ; in inorganic salt solutions other than ammonium salt solutions
- C22B3/08—Sulfuric acid, other sulfurated acids or salts thereof
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
- C22B3/04—Extraction of metal compounds from ores or concentrates by wet processes by leaching
- C22B3/06—Extraction of metal compounds from ores or concentrates by wet processes by leaching in inorganic acid solutions, e.g. with acids generated in situ; in inorganic salt solutions other than ammonium salt solutions
- C22B3/10—Hydrochloric acid, other halogenated acids or salts thereof
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
- C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
- C22B3/44—Treatment or purification of solutions, e.g. obtained by leaching by chemical processes
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- 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
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Mechanical Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Metallurgy (AREA)
- Environmental & Geological Engineering (AREA)
- Inorganic Chemistry (AREA)
- Geochemistry & Mineralogy (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
The invention discloses a method for extracting valuable rare earth from bastnaesite at low cost, which comprises the following steps: A. oxidizing and roasting bastnaesite rare earth concentrate, and then leaching with hydrochloric acid to obtain primary leaching liquid and primary leaching slag; B. sulfuric acid secondary leaching is carried out on the primary leaching slag to obtain secondary leaching liquid and secondary leaching slag; C. adding calcium chloride into the secondary leaching solution, and filtering to obtain first filter residue and first filtrate; D. adding hydrogen peroxide into the first filtrate, and filtering to obtain second filter residue and second filtrate. According to the invention, the obtained rare earth sulfate solution is transformed into a rare earth chloride system by using calcium chloride after acid leaching twice, and the cerium fluoride product is directly obtained through hydrogen peroxide reduction and precipitation under the condition of not increasing the cost of rare earth transformation, so that the production flow is reduced, the wastewater treatment capacity is reduced, meanwhile, the byproducts of calcium sulfate and cerium fluoride are also obtained, and the cost of the production process is further reduced.
Description
Technical Field
The invention relates to the technical field of rare earth hydrometallurgy, in particular to a method for extracting valuable rare earth from bastnaesite with low cost.
Background
The bastnaesite ore in China is mainly distributed in the rare earth mine of Yak apron, mountain east micro mountain rare earth mine and the Bayan jaw rare earth of inner Mongolia in the crown county of Sichuan province, wherein the Bayan jaw rare earth ore is mainly mixed rare earth ore of bastnaesite and monazite ore. The highest purity of domestic bastnaesite is bastnaesite rare earth concentrate of yak apron mine of Sichuan province, wherein the fluorine content in the bastnaesite is 7-11%, and the fluorine is mainly REFCO 3 CaF or REF 3 In the form of (2), the rare earth oxide must be extracted from bastnaesite, and the fluorine in the ore must be removed.
The existing extraction of rare earth oxides in bastnaesite is mainly based on two ideas: the method is characterized in that fluorine in bastnaesite is formed into fluorine-containing soluble fluoride salt or volatile fluorine-containing waste gas, then for environmental safety, enterprises need to recover fluorine in wastewater and fluorine in waste gas through safe and environment-friendly equipment, and the fluorine can be discharged after reaching standards, and the production process for generating the soluble fluorine-containing wastewater generally adopts an oxidizing roasting-acid-alkali combined leaching method to decompose bastnaesite, and the method for generating the fluorine-containing waste gas mainly comprises a sulfuric acid roasting method to decompose bastnaesite rare earth concentrate; the other method adopts a fluorine fixing method or a complexing decomposition method, but the method increases the technological process of rare earth treatment for a while and causes the waste of fluorine resources in bastnaesite.
Chinese patent CN102146512a discloses a smelting separation process of bastnaesite, which uses primary and/or secondary slag obtained by oxidizing, roasting and hydrochloric acid leaching bastnaesite as raw material, carries out sulfuric acid in and out to obtain rare earth sulfate solution and filter residue, and uses organic extractant to carry out countercurrent extraction on the rare earth sulfate solution to obtain rare earth compound, fluorine washing liquid, pure cerium product and thorium product. The technology of the patent needs to use an organic extractant for transformation, so that the process flow is increased, more waste water is generated after the transformation of the organic extractant, a waste water treatment process and a rare earth recovery process are required to be added, and meanwhile, fluorine resources in the whole separation process also need to be independently recovered, so that the cost of the rare earth separation process is further increased.
Chinese patent CN102465203a discloses a method for directly preparing cerium fluoride in the process of extraction and separation, which uses rare earth sulfate solution or rare earth nitrate solution as raw material, and adopts organic extractant to make extraction and separation, then adopts back extraction solution formed from inorganic acid and reducer to make back extraction, and adds cerium fluoride as seed crystal to make precipitation crystallization, and then filters to obtain cerium fluoride powder. Correspondingly, the technology of the patent also needs to use an organic extractant for transformation, so that the process flow is increased, more waste water is generated after the transformation of the organic extractant, a waste water treatment process and a rare earth recovery process are needed to be added, and special stripping liquid and cerium fluoride seed crystal are needed to be added for stripping and recovery when cerium and fluorine are recovered, so that the consumption of auxiliary material cost is increased.
Disclosure of Invention
The invention aims at: aiming at the problems, the invention provides a method for extracting valuable rare earth from bastnaesite with low cost, which converts the obtained rare earth sulfate solution into a rare earth chloride system by adopting calcium chloride after acid leaching twice, and directly obtains the cerium fluoride product by hydrogen peroxide reduction precipitation under the condition of not increasing the cost of rare earth conversion, thereby not only reducing the production flow, but also reducing the wastewater treatment capacity, reducing the loss of valuable rare earth and the loss of fluorine resources, simultaneously obtaining the byproducts of calcium sulfate and cerium fluoride, and further reducing the cost of the production process.
The technical scheme adopted by the invention is as follows: a method for extracting valuable rare earth from bastnaesite at low cost, comprising the following steps:
A. oxidizing and roasting bastnaesite rare earth concentrate, and then leaching with hydrochloric acid to obtain primary leaching liquid and primary leaching slag;
B. sulfuric acid secondary leaching is carried out on the primary leaching slag to obtain secondary leaching liquid and secondary leaching slag;
C. adding calcium chloride into the secondary leaching solution, stirring for reaction, and filtering to obtain first filter residue and first filtrate;
D. adding hydrogen peroxide into the first filtrate, stirring for reaction, and filtering to obtain second filter residues and second filtrate;
E. mixing the primary leaching solution and the second filtrate, removing impurities and concentrating to obtain the mixed rare earth chloride solution.
In the invention, the grade REO of bastnaesite rare earth concentrate is more than or equal to 65 percent, when the bastnaesite rare earth concentrate is oxidized and roasted in a rotary kiln, the roasting temperature is generally between 450 and 520 ℃, the oxidizing and roasting time is generally about 2 hours, oxidized rare earth roasting ore is produced, the oxidizing process is that rare earth carbonate in bastnaesite is decomposed into oxyfluoride rare earth, intermediate-valence rare earth ions are oxidized into high-valence rare earth ions, the rare earth oxidation rate is more than or equal to 96 percent, and the reaction equation is as follows:
2REF 3 .RE 2 (CO 3 ) 3 →3REOF+6CO 2 ↑+RE 2 O 3 +REF 3
2CeF 3 .Ce 2 (CO 3 ) 3 +3/2O 2 →3CeOF 2 +6CO 2 ↑+3CeO 2
further, the general process of primary hydrochloric acid leaching is as follows: at normal temperature, water and roasted ore are prepared into ore pulp according to the mass ratio of 2:1 (the proportion relation can be adjusted according to actual conditions), then industrial hydrochloric acid (the mass fraction is 31%) is slowly added into the ore pulp, in the process of adding the hydrochloric acid, the acidity in a reaction system is controlled below 0.2mol/L at any time, a small amount of tetravalent cerium is ensured to be leached, and CeO is ensured in primary leaching liquid 2 REO +.5% (cerium oxide)The content of the rare earth is not more than 5 percent of the total rare earth amount), and the reaction equation is as follows:
3REOF+6HCl→2RECl 3 +REF 3 +3H 2 O
RE 2 O 3 +6HCl→2RECl 3 +3H 2 O
CeO 2 +CeOF 2 +6HCl→CeCl 3 +CeF 3 +3H 2 O+3/2Cl 2 ↑
note that: in the actual production process, a small part of tetravalent cerium is leached out, and is reduced to trivalent cerium by hydrochloric acid to generate chlorine.
In the hydrochloric acid leaching process, after primary leaching slag in a reaction system is observed to be off-white, stopping adding acid, then continuously stirring and reacting for about 1.5 hours under the condition of stirring the whole system, stopping stirring and clarifying, extracting supernatant, filtering, mixing filtrate and supernatant to form primary leaching liquid, wherein the primary leaching liquid is a mixed rare earth solution, and filter residues are used as primary leaching slag and mainly contain rare earth fluoride and other insoluble impurities.
In the invention, the sulfuric acid rare earth solution can be obtained by directly adopting primary acid leaching, namely, the sulfuric acid leaching is directly carried out, but the treatment capacity of a transformation process is increased, and the yield of valuable rare earth is influenced, so that in order to improve the treatment effect, the method preferably adopts a mode of twice acid leaching, namely, the primary leaching slag obtained after primary hydrochloric acid leaching is subjected to sulfuric acid leaching, and the leaching process is as follows: transferring the primary leaching slag into a reaction kettle, and leaching the slag according to the primary mass ratio: water=1:20 (the proportion relation can be adjusted according to actual conditions), stirring and mixing, directly adding sulfuric acid solution (the concentration of the sulfuric acid solution is not particularly required, for example, sulfuric acid solution with the concentration of 3-6mol/L can be selected), controlling the acidity of a reaction system to be 2.5+/-0.5 mol/L, keeping the temperature of the system at normal temperature, stirring and reacting for about 6 hours until the concentration of residual acid is 0.2+/-0.1 mol/L, and completely reacting, wherein the main reaction equation is as follows:
3CeO 2 +2REF 3 +3CeOF 2 +9H 2 SO 4 ＝6[CeF 2 ]SO 4 +9H 2 O+RE 2 (SO 4 ) 3
ThO 2 +2H 2 SO 4 ＝Th 2 (SO 4 ) 3 +H 2 O
Fe 2 O 3 +H 2 SO 4 ＝Fe 2 (SO 4 ) 3 +H 2 O
in the process, the rare earth fluoride in the primary leaching slag is converted into a soluble fluorine-containing sulfuric acid rare earth complex through sulfuric acid, so that separation of the rare earth fluoride and other impurities is realized, secondary leaching liquid and secondary leaching slag are obtained after filtration, the secondary leaching liquid is a sulfuric acid rare earth solution, and the secondary leaching slag is transferred into a warehouse for temporary storage.
In the invention, the secondary leaching solution is transferred into a reaction kettle to be stirred, and then calcium chloride is added, wherein the calcium chloride can be in a water solution form or a solid form, and is preferably selected, so that the cost of auxiliary materials is saved, the calcium chloride is derived from calcium soap in a rare earth extraction section and organically participates in calcium chloride acid waste liquid generated after smelting and separating, and therefore, the additional purchase of the calcium chloride auxiliary materials is avoided, the treatment of the waste liquid can be realized, and the transformation cost of rare earth sulfate is not increased. Further, after calcium chloride is added, but after precipitation in the reaction system is not increased, the addition of the calcium chloride is stopped to control CaO less than or equal to 1g/L in the reaction system, after the reaction is completed, the first filtrate and first filter residue are obtained by filtering, and the reaction equation is as follows:
RE 2 (SO 4 ) 3 +Ca 2+ ＝CaSO 4 +RE 3+
the first filter residue is calcium sulfate, which can be used as a common solid waste warehouse for temporary storage, and can also be directly used as a building material for resale to a cement plant. Transferring the first filtrate into a reaction kettle, heating the first filtrate to above 60 ℃, generally at 60-80 ℃, wherein the temperature cannot be too high or too low, so that energy is wasted, and meanwhile, the generation of chlorine is accelerated due to too high temperature; too low affects the oxidation-reduction property of hydrogen peroxide, and simultaneously reduces the precipitation efficiency, then hydrogen peroxide is slowly added, white precipitate is generated in the reaction kettle, and the reaction equation is as follows:
[CeF 2 ] 2+ +H 2 O 2 ＝CeF 3 ↓+H 2 O+O 2
during this reaction, ce 4+ Is reduced to Ce 3+ And combining with fluoride ions to form cerium trifluoride to be precipitated, stopping adding hydrogen peroxide after white precipitate is not increased, filtering to obtain second filter residue and second filtrate, washing the second filter residue by reaction water, drying to obtain cerium trifluoride product with purity of more than 99.00%, mixing the washing water with the second filtrate, mixing the second filtrate with the primary leaching solution, taking the second filtrate as a mixed rare earth chloride solution raw material, and sending the mixed rare earth chloride solution raw material to an extraction separation process for extraction separation.
In summary, due to the adoption of the technical scheme, the beneficial effects of the invention are as follows:
1. the invention adopts a two-step acid leaching method to leach valuable rare earth, the obtained sulfuric acid rare earth is not subjected to hydrochloric acid leaching after double salt precipitation and alkali conversion, and is not subjected to conversion by adopting organic extractants (P204 and P507), but is directly converted into a rare earth chloride system by utilizing calcium chloride waste liquid, and meanwhile, cerium fluoride products are generated by hydrogen peroxide reducer, so that the production treatment flow is reduced, the use cost of auxiliary materials and the wastewater treatment capacity are also reduced, and the loss of valuable rare earth and fluorine resources is reduced, thereby reducing the production process cost as a whole, and having the characteristic of obvious low cost;
2. the waste residue calcium sulfate generated in the production process can be used as building materials such as cement, is convenient to treat, and the produced cerium fluoride can form rare earth fluoride with purity of more than 98% after being washed for many times, so that the added value is increased, the treatment capacity of fluorine-containing wastewater is reduced, and the waste of fluorine resources is effectively reduced;
3. the extraction method has the valuable rare earth yield of more than 93 percent, and the valuable rare earth yield of about 54 percent by an acid-base combination method, so that the rare earth yield is effectively ensured.
Drawings
FIG. 1 is a schematic flow chart of a method for extracting valuable rare earth from bastnaesite at low cost according to the invention.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings.
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
As shown in fig. 1, a method for extracting valuable rare earth from bastnaesite at low cost comprises the following steps:
A. oxidizing and roasting bastnaesite rare earth concentrate, and then leaching with hydrochloric acid to obtain primary leaching liquid and primary leaching slag;
B. sulfuric acid secondary leaching is carried out on the primary leaching slag to obtain secondary leaching liquid and secondary leaching slag;
C. adding calcium chloride into the secondary leaching solution, stirring for reaction, and filtering to obtain first filter residue and first filtrate;
D. adding hydrogen peroxide into the first filtrate, stirring for reaction, and filtering to obtain second filter residues and second filtrate;
E. mixing the primary leaching solution and the second filtrate, removing impurities and concentrating to obtain the mixed rare earth chloride solution.
In order to better illustrate the technical effects of the present invention, some examples are listed below:
example 1
S1, taking rare earth roasting ore with weight of 1 ton REO being 75% bastnaesite, pulping according to solid-to-liquid ratio of 1:2, adding 370L concentrated hydrochloric acid with acidity of 31% to operate in a mode of dissolving bastnaesite oxidized roasting ore according to an acid-base combination method, and filtering through a plate frame to obtain CeO with concentration of 112g/L 2 TREO:3.8% of mixed rare earth chloride 2.2, wherein the filtrate is called primary leaching solution, and the filtered slag is called primary leaching slag;
s2, transferring the primary leaching residue into a reaction tank, adding the clear water slurry into the primary leaching residue at a residue-liquid ratio of 1:20, and then adding 720L of dilute sulfur with a concentration of 6mol/L into the reaction tankAcid, reacting for 6h, and then filtering the whole system; the leaching solution is secondary leaching solution, and the filter residue is secondary leaching residue; the REO concentration of the secondary leaching solution is 23.4g/L, and CeO concentration is 23.4g/L 2 REO was 65.44% and fluoride ion concentration was 5.4g/L, with 19.5 cubes of solution; packaging the leached residues and transferring the leached residues into a warehouse for temporary storage;
s3, mixing the calcium chloride-containing wastewater produced in the extraction section with a rare earth sulfate solution, wherein the calcium chloride is kept to be slightly excessive in the mixing process of the two solutions, so that the calcium content in the whole system is ensured to be less than 1g/L, and after the reaction is completed, filtering the mixed solution of the whole system to obtain a first filtrate and a first filter residue, wherein the first filter residue is sold as gypsum, and the rare earth content of the first filter residue is 0.035%;
s4, transferring 5 cubes of the first filtrate into a reaction kettle, and starting stirring, wherein the REO concentration of the filtrate is 22.3g/L, and the CeO concentration is high 2 REO is 65.44%; then hydrogen peroxide is slowly added at room temperature until white precipitate is not generated in the reaction kettle and the generation of chlorine can be stopped, stirring is carried out for 0.5h, clarifying and filtering are carried out, filtrate is rare earth chloride solution, and filter residues are rare earth fluoride; 90.25kg of rare earth fluoride is obtained after drying, and the cerium content is sampled and analyzed to be CeO 2 REO is 82.37%;
s5, transferring 5 cubes of the first filtrate into a reaction kettle, and starting stirring, wherein the REO concentration of the filtrate is 22.3g/L, and the CeO concentration is high 2 And (2) adding hydrogen peroxide slowly after heating the rare earth sulfate solution to 60 ℃ until white precipitate is not generated and the generation of chlorine can be stopped in the reaction kettle, stirring for 0.5h, clarifying, filtering, wherein filtrate is rare earth chloride, and filter residues are rare earth fluoride; 94.5kg of rare earth fluoride is obtained after drying; sampling analysis of cerium content as CeO 2 REO is 99.37%, and the comprehensive rare earth yield is 93.15% (calculated by 100% of rare earth solution).
The comparison between the steps S4 and S5 can be achieved, when the first filtrate is not heated but hydrogen peroxide is directly added, the reaction of the hydrogen peroxide and tetravalent cerium is slowed down, part of tetravalent cerium is released and reacts with chlorine radicals to generate a large amount of chlorine gas, so that the yield of cerium fluoride is reduced, and meanwhile, the purity of cerium fluoride is reduced due to the combination of free fluoride ions and trivalent rest rare earth ions.
Example 2
250kg of the rare earth roasting ore in the same batch in the example 1 is transferred into a reaction kettle, pulped (solid-liquid ratio: 1:25), and then added with 300L of dilute sulfuric acid with the concentration of 6mol/L for reaction for 6 hours, so as to obtain a rare earth sulfate solution with the concentration of 25.5g/L in the 6.5-side; wherein CeO is 2 REO is 53.21%;
s2, mixing the calcium chloride-containing wastewater (industrial calcium chloride solid can be directly used) produced in the extraction section with a 6.5-side rare earth sulfate solution, keeping a small excess of calcium chloride in the mixing process of the two solutions, ensuring that the calcium content in the whole system is less than 1g/L, and after the reaction is completed, filtering the mixed solution of the whole system to obtain a first filtrate and a first filter residue, wherein the first filter residue is sold as gypsum, and the rare earth content of the first filter residue is 0.054%;
s3, taking 5 parts of the first filtrate, transferring a rare earth sulfate solution with the rare earth concentration of 24.5g/L into a reaction kettle, heating to 60 ℃, slowly adding hydrogen peroxide, stopping adding hydrogen peroxide after white precipitate is not generated in the reaction process, continuously stirring for 0.5h, stopping stirring, clarifying and filtering, wherein the filtrate is rare earth chloride, the filter residue is rare earth fluoride, 90kg of rare earth fluoride is obtained after drying, and the cerium content is CeO in a sampling analysis manner 2 REO is 99.33%, and the comprehensive rare earth yield is 88.13% (calculated by 100% of rare earth solution).
From the above, it is known that the roasting ore is directly leached by sulfuric acid to form a sulfuric acid rare earth solution, and the sulfuric acid system is required to be converted into a rare earth chloride system to be used for extraction and separation of the hydrochloric acid system-P507, so that the leaching of the roasting ore by sulfuric acid directly increases the water consumption for treating the roasting ore and the amount of the sulfuric acid rare earth solution to be converted, which not only results in the increase of the cost, but also results in the leaching rate of the rare earth of 88.4% by sulfuric acid in example 2, which is lower than the leaching rate of 93.5% in example 1.
Example 3
S1, taking the secondary leaching solution obtained in the example 1 as a raw material, carrying out 5-level countercurrent extraction by adopting P507+ sulfonated kerosene with the concentration of 1.5mol/L in a mode of 1:1, wherein tetravalent cerium containing fluoride ions and a small amount of trivalent rare earth ions are extracted into a loaded organic, washing the loaded organic by using sulfuric acid solution with the concentration of 0.5mol/L, and washing a small amount of trivalent rare earth in the loaded organic into a washing solution to be used as bottom water for leaching primary acid leaching residues; then preparing aluminum sulfate in nitric acid with the concentration of 1mol/L, and washing the loaded organic by using a preparation solution according to F/Al=1.4 (molar ratio) to obtain fluorine-washing liquid with the Al content of 8.65g/L and the F content of 8.5g/L in the 2-side;
s2, reducing and back-extracting cerium by using 2mol/L hydrogen peroxide and 6mol/L hydrochloric acid according to a ratio of 12:1 to obtain a pure cerium product with the purity of 99.1%, wherein the yield is 86g, washing the organic by using sulfuric acid with the concentration of 3mol/L, washing the organic by using clear water, clarifying, and performing cross extraction;
s3, heating the fluorine washing liquid to 90 ℃, adding sodium hydroxide to adjust the PH value to 5, and reacting to obtain cryolite, wherein the content of the cryolite rare earth is 0.25%.
According to the production statistics of the applicant, the same 1 ton bastnaesite rare earth concentrate is treated, and compared with the acid-base combination method adopted previously, the low-cost valuable rare earth extraction method disclosed by the invention has the advantages that the treatment period is saved by 2 days, the waste water amount of 18t is reduced, the direct production cost of raw materials is saved by about 1100 yuan, and therefore, the practicability in actual production is extremely strong.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (10)
1. A method for extracting valuable rare earth from bastnaesite at low cost, which is characterized by comprising the following steps:
A. oxidizing and roasting bastnaesite rare earth concentrate, and then leaching with hydrochloric acid to obtain primary leaching liquid and primary leaching slag;
B. sulfuric acid secondary leaching is carried out on the primary leaching slag to obtain secondary leaching liquid and secondary leaching slag;
C. adding calcium chloride into the secondary leaching solution, stirring for reaction, and filtering to obtain first filter residue and first filtrate;
D. adding hydrogen peroxide into the first filtrate, stirring for reaction, and filtering to obtain second filter residues and second filtrate;
E. mixing the primary leaching solution and the second filtrate, removing impurities and concentrating to obtain the mixed rare earth chloride solution.
2. The method for extracting valuable rare earth from bastnaesite at low cost according to claim 1, wherein in the step a, the calcined ore obtained by the oxidative roasting is mixed with water to prepare a pulp, hydrochloric acid is added to the pulp, and the acidity of the reaction system is controlled to be not more than 0.2mol/L.
3. The method for low-cost extraction of valuable rare earth from bastnaesite according to claim 2, wherein the cerium oxide content in the primary leachate is controlled to be not more than 5% of the total rare earth content in terms of cerium oxide.
4. The method for low-cost extraction of valuable rare earth from bastnaesite according to claim 1, wherein in the step B, sulfuric acid is added after the primary leaching residue is mixed with water, the acidity of the reaction system is controlled to be 2.5 + -0.5 mol/L, and the concentration of residual acid after the reaction is controlled to be 0.2 + -0.1 mol/L.
5. The method for low-cost extraction of valuable rare earth from bastnaesite according to claim 1, wherein in the step C, the calcium chloride is derived from calcium chloride acidic waste liquid generated after the organic participation of calcium soap in the rare earth extraction section in smelting separation.
6. The method for low-cost extraction of valuable rare earth from bastnaesite according to claim 1, wherein in the step C, the concentration of calcium oxide in the reaction system is controlled to not more than 1g/L in terms of calcium oxide.
7. The method for low-cost extraction of valuable rare earth from bastnaesite according to claim 1, wherein in step D, the first filtrate is heated to 60 ℃ or higher and then hydrogen peroxide is added.
8. The method for low-cost extraction of valuable rare earth from bastnaesite according to claim 1, wherein in step D, the obtained second filter residue is dried to obtain cerium fluoride product.
9. The method for extracting valuable rare earth from bastnaesite at low cost according to claim 1, wherein the first filter residue is dried to obtain calcium sulfate product.
10. The method for extracting valuable rare earth from bastnaesite at low cost according to any one of claims 1 to 9, wherein the rare earth chloride mixture is subjected to organic extraction to obtain rare earth products.
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