CN116692932A - Method for preparing lead iodide crystals by reducing lead plaster through wet short process - Google Patents
Method for preparing lead iodide crystals by reducing lead plaster through wet short process Download PDFInfo
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- XMBWDFGMSWQBCA-UHFFFAOYSA-N hydrogen iodide Chemical compound I XMBWDFGMSWQBCA-UHFFFAOYSA-N 0.000 title claims abstract description 126
- 238000000034 method Methods 0.000 title claims abstract description 84
- 239000013078 crystal Substances 0.000 title claims abstract description 75
- 239000011505 plaster Substances 0.000 title claims abstract description 53
- 230000008569 process Effects 0.000 title claims abstract description 47
- 239000000243 solution Substances 0.000 claims abstract description 110
- 238000006243 chemical reaction Methods 0.000 claims abstract description 84
- 239000007788 liquid Substances 0.000 claims abstract description 66
- 238000000926 separation method Methods 0.000 claims abstract description 48
- 239000007787 solid Substances 0.000 claims abstract description 34
- 238000003756 stirring Methods 0.000 claims abstract description 26
- 239000002699 waste material Substances 0.000 claims abstract description 24
- 239000003960 organic solvent Substances 0.000 claims abstract description 23
- 239000002253 acid Substances 0.000 claims abstract description 21
- 239000000706 filtrate Substances 0.000 claims abstract description 20
- 239000012266 salt solution Substances 0.000 claims abstract description 18
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 16
- 238000003860 storage Methods 0.000 claims abstract description 13
- NLKNQRATVPKPDG-UHFFFAOYSA-M potassium iodide Chemical compound [K+].[I-] NLKNQRATVPKPDG-UHFFFAOYSA-M 0.000 claims description 44
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical group CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 31
- 229940071870 hydroiodic acid Drugs 0.000 claims description 30
- FVAUCKIRQBBSSJ-UHFFFAOYSA-M sodium iodide Chemical compound [Na+].[I-] FVAUCKIRQBBSSJ-UHFFFAOYSA-M 0.000 claims description 18
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 17
- -1 iodide ions Chemical class 0.000 claims description 16
- 238000006722 reduction reaction Methods 0.000 claims description 16
- 230000009467 reduction Effects 0.000 claims description 13
- 238000001816 cooling Methods 0.000 claims description 11
- 238000010438 heat treatment Methods 0.000 claims description 11
- 238000001953 recrystallisation Methods 0.000 claims description 9
- 238000004090 dissolution Methods 0.000 claims description 6
- 235000009518 sodium iodide Nutrition 0.000 claims description 6
- 239000003638 chemical reducing agent Substances 0.000 claims description 5
- 230000001105 regulatory effect Effects 0.000 claims description 5
- XZXYQEHISUMZAT-UHFFFAOYSA-N 2-[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenol Chemical compound CC1=CC=C(O)C(CC=2C(=CC=C(C)C=2)O)=C1 XZXYQEHISUMZAT-UHFFFAOYSA-N 0.000 claims description 4
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 4
- 229940107816 ammonium iodide Drugs 0.000 claims description 4
- 239000011259 mixed solution Substances 0.000 claims description 4
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 claims description 3
- 229910052786 argon Inorganic materials 0.000 claims description 2
- 239000011261 inert gas Substances 0.000 claims description 2
- 238000002156 mixing Methods 0.000 claims description 2
- 239000011734 sodium Substances 0.000 claims description 2
- 239000003153 chemical reaction reagent Substances 0.000 abstract description 29
- 239000000047 product Substances 0.000 abstract description 15
- 238000002360 preparation method Methods 0.000 abstract description 13
- 238000004064 recycling Methods 0.000 abstract description 5
- 239000000203 mixture Substances 0.000 abstract description 3
- 239000012528 membrane Substances 0.000 description 18
- PIJPYDMVFNTHIP-UHFFFAOYSA-L lead sulfate Chemical compound [PbH4+2].[O-]S([O-])(=O)=O PIJPYDMVFNTHIP-UHFFFAOYSA-L 0.000 description 15
- 150000002500 ions Chemical class 0.000 description 14
- 238000001914 filtration Methods 0.000 description 12
- 239000000126 substance Substances 0.000 description 12
- 238000006477 desulfuration reaction Methods 0.000 description 11
- 230000023556 desulfurization Effects 0.000 description 11
- 238000001035 drying Methods 0.000 description 10
- 239000002904 solvent Substances 0.000 description 10
- 238000004448 titration Methods 0.000 description 10
- 239000002994 raw material Substances 0.000 description 9
- 238000000967 suction filtration Methods 0.000 description 9
- 230000026045 iodination Effects 0.000 description 7
- 238000006192 iodination reaction Methods 0.000 description 7
- 229910052740 iodine Inorganic materials 0.000 description 7
- 239000011630 iodine Substances 0.000 description 7
- 238000002386 leaching Methods 0.000 description 7
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 239000012535 impurity Substances 0.000 description 6
- HTUMBQDCCIXGCV-UHFFFAOYSA-N lead oxide Chemical compound [O-2].[Pb+2] HTUMBQDCCIXGCV-UHFFFAOYSA-N 0.000 description 5
- 238000001556 precipitation Methods 0.000 description 5
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 4
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 150000002496 iodine Chemical class 0.000 description 4
- 238000000746 purification Methods 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 239000006227 byproduct Substances 0.000 description 3
- 230000001276 controlling effect Effects 0.000 description 3
- 230000003009 desulfurizing effect Effects 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- AFCARXCZXQIEQB-UHFFFAOYSA-N N-[3-oxo-3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CCNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 AFCARXCZXQIEQB-UHFFFAOYSA-N 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 239000003929 acidic solution Substances 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- YADSGOSSYOOKMP-UHFFFAOYSA-N dioxolead Chemical compound O=[Pb]=O YADSGOSSYOOKMP-UHFFFAOYSA-N 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 229940046892 lead acetate Drugs 0.000 description 2
- RLJMLMKIBZAXJO-UHFFFAOYSA-N lead nitrate Chemical compound [O-][N+](=O)O[Pb]O[N+]([O-])=O RLJMLMKIBZAXJO-UHFFFAOYSA-N 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- KEQXNNJHMWSZHK-UHFFFAOYSA-L 1,3,2,4$l^{2}-dioxathiaplumbetane 2,2-dioxide Chemical compound [Pb+2].[O-]S([O-])(=O)=O KEQXNNJHMWSZHK-UHFFFAOYSA-L 0.000 description 1
- USFZMSVCRYTOJT-UHFFFAOYSA-N Ammonium acetate Chemical compound N.CC(O)=O USFZMSVCRYTOJT-UHFFFAOYSA-N 0.000 description 1
- 239000005695 Ammonium acetate Substances 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- AFVFQIVMOAPDHO-UHFFFAOYSA-N Methanesulfonic acid Chemical compound CS(O)(=O)=O AFVFQIVMOAPDHO-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 229910020282 Pb(OH) Inorganic materials 0.000 description 1
- NPYPAHLBTDXSSS-UHFFFAOYSA-N Potassium ion Chemical compound [K+] NPYPAHLBTDXSSS-UHFFFAOYSA-N 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 229940043376 ammonium acetate Drugs 0.000 description 1
- 235000019257 ammonium acetate Nutrition 0.000 description 1
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium peroxydisulfate Substances [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 description 1
- 229910001870 ammonium persulfate Inorganic materials 0.000 description 1
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000006837 decompression Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000029087 digestion Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000009775 high-speed stirring Methods 0.000 description 1
- XMBWDFGMSWQBCA-UHFFFAOYSA-M iodide Chemical compound [I-] XMBWDFGMSWQBCA-UHFFFAOYSA-M 0.000 description 1
- 229940006461 iodide ion Drugs 0.000 description 1
- 229910052745 lead Inorganic materials 0.000 description 1
- 229940075539 lead iodide preparation Drugs 0.000 description 1
- 229910000464 lead oxide Inorganic materials 0.000 description 1
- JQJCSZOEVBFDKO-UHFFFAOYSA-N lead zinc Chemical compound [Zn].[Pb] JQJCSZOEVBFDKO-UHFFFAOYSA-N 0.000 description 1
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 1
- RVPVRDXYQKGNMQ-UHFFFAOYSA-N lead(2+) Chemical compound [Pb+2] RVPVRDXYQKGNMQ-UHFFFAOYSA-N 0.000 description 1
- YWCLWGMTGGFSDF-UHFFFAOYSA-N lead;dihydrate Chemical compound O.O.[Pb] YWCLWGMTGGFSDF-UHFFFAOYSA-N 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000012046 mixed solvent Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 229910001414 potassium ion Inorganic materials 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G21/00—Compounds of lead
- C01G21/16—Halides
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/54—Reclaiming serviceable parts of waste accumulators
-
- 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
-
- 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
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/84—Recycling of batteries or fuel cells
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
Abstract
The invention belongs to the technical field of waste lead acid storage battery recycling and lead iodide crystal preparation, and discloses a method for preparing lead iodide crystals by reducing lead plaster in a wet short process, which comprises the following steps: s1: collecting and reducing waste lead plaster in the waste lead acid storage battery to obtain reduced lead plaster; placing the reduced lead plaster into an iodized salt solution, and stirring to obtain a primary reaction solution; s2: adding a hydriodic acid solution into the mixture, and then carrying out solid-liquid separation to obtain a solid, namely a coarse crystal; s3: dissolving the crude crystals in an organic solvent, and then carrying out solid-liquid separation; the obtained filtrate is lead iodide solution; s4: and recrystallizing the lead iodide solution, and then carrying out solid-liquid separation to obtain a solid, namely the purified lead iodide crystal. The preparation method can realize the preparation of the lead iodide crystal through the short process by improving the overall designs of reaction participators and the process flow, and the like, and can effectively solve the technical problems of long process steps, large reagent input and low purity of the lead iodide product in the prior art.
Description
Technical Field
The invention belongs to the technical field of recycling of waste lead acid storage batteries and preparation of lead iodide crystals, and particularly relates to a method for preparing lead iodide crystals by a wet short process of reduction of lead paste.
Background
Lead iodide is one of the most important raw materials in the preparation process of lead-based perovskite solar cells, and along with the increasing development of the photovoltaic industry and the increasing perfection of the large-scale industrialization of the perovskite solar cells, the market demand of lead iodide is gradually increased, in particular to high-purity lead iodide. The current preparation process of commercial lead iodide raw materials uses an electrolytically refined lead ingot for acid leaching and iodination, a large amount of acid reagents and energy are consumed in the process, and process byproducts cannot be recycled and have low utilization value. On the other hand, as the specific gravity of lithium batteries in the secondary battery market increases, a large number of waste lead acid batteries cannot find the digestion scene, and most common lead acid batteries are pyrometallurgically recovered to produce a large amount of SO 2 Lead-containing smoke and dust, which is extremely harmful to the environment. If the lead-containing component in the lead-acid storage battery can be subjected to short-flow wet recovery, purification and further conversion into lead iodide, a clean and various recovery path can be provided for the synthesis of the lead iodide, and a brand-new application scene can be provided for excessive regenerated lead resources.
CN201810188405.0 and CN201810184271.5 disclose a process for preparing lead iodide crystals by using lead acetate and lead nitrate, which are lead-containing reagents obtained from raw lead such as lead ingots by acid leaching, and in the synthesis process of such reagents, strong acid solution (such as nitric acid) needs to be used for reacting with Pb, the dosage is large, the reagent input amount is large in the whole process, and the environmental pollution is serious. CN201910412336.1 discloses a process for synthesizing lead iodide from lead zinc ore by wet method, separating lead and zinc components by ammonia water-ammonium sulfate-ammonium persulfate mixed solution, and sequentially treating lead-containing components by sulfuric acid, ammonium acetate and potassium iodide solution to obtain lead iodide solid. The method uses raw materials belonging to primary lead materials, reduces the use of primary lead under the condition that the secondary lead resources exceed market demands, and adds more than 6 reagents, so that the process is longer. CN201911357146.0 discloses a process from waste lead acid storage battery to lead iodide, which comprises the steps of strong alkali desulfurization, hydrogen peroxide reduction, sulfuric acid precipitation, methylsulfonic acid leaching, potassium iodide precipitation and the like, 6 reagents are added, the process is longer, and purification of lead iodide products is not considered in the process, so that impurities such as Fe, ba, sb and the like in the lead acid storage battery can enter lead iodide crystals.
In summary, the existing lead iodide preparation process flow is long, the steps of desulfurization, reduction, leaching, precipitation and the like are carried out, a large amount of reagents are added in the process, and the reagents cannot be recycled, so that great waste is caused. There is a need to develop a new process of short-flow wet process from waste lead paste to high-purity lead iodide.
Disclosure of Invention
Aiming at the defects or improvement demands of the prior art, the invention aims to provide a method for preparing lead iodide crystals by reducing lead plaster through a wet method in a short process, wherein the preparation of the lead iodide crystals can be realized through the short process by improving the overall designs of reaction participants and the process flow, and the technical problems of long process steps, large reagent input and low purity of lead iodide products in the prior art can be effectively solved. In addition, the method has the advantages of small addition amount of the reagent used in the technical process, high conversion efficiency, low impurity content and few byproducts, and realizes the short-process clean conversion from waste lead paste to high-purity lead iodide.
In order to achieve the above object, the present invention provides a method for preparing lead iodide crystals by reducing lead plaster in a wet short process, which is characterized by comprising the following steps:
s1: collecting waste lead paste in the waste lead acid storage battery and carrying out reduction treatment to obtain reduced lead paste without +4-valent Pb element; then, placing the reduced lead plaster in an iodized salt solution, wherein the molar ratio of iodide ions in the iodized salt solution to lead elements in the reduced lead plaster is 2:1-4:1; then, stirring and reacting for 0.5-2 h to obtain a primary reaction solution;
s2: adding a hydriodic acid solution into the primary reaction solution obtained in the step S1, regulating the pH value to 2.0-6.0, and fully reacting and then carrying out solid-liquid separation; the solid obtained by the solid-liquid separation is coarse crystal;
s3: placing the crude crystal obtained in the step S2 into an organic solvent for dissolution and then carrying out solid-liquid separation; the filtrate obtained by the solid-liquid separation is lead iodide solution;
s4: recrystallizing the lead iodide solution obtained in the step S3, and then carrying out solid-liquid separation; the solid obtained by solid-liquid separation is the purified lead iodide crystal.
In the step S1, the reduced lead plaster is obtained by roasting and reducing waste lead plaster in a lead-acid storage battery at a high temperature or performing a reduction reaction with a reducing agent; wherein the temperature adopted by the high-temperature roasting reduction is 300-600 ℃, and the atmosphere adopted by the high-temperature roasting reduction is air and N 2 Or an inert gas, more preferably argon; the reducing agent is H 2 O 2 Or sulfite, more preferably Na 2 SO 3 。
As a further preferred aspect of the present invention, the solid obtained by the solid-liquid separation in the step S3 can be reused as the reduced lead paste in the step S1;
the filtrate obtained by the solid-liquid separation in the step S4 can be used as an organic solvent to be repeatedly used in the step S3.
As a further preferred aspect of the present invention, in the step S2, the reaction is specifically a stirring reaction for 10min to 30min;
in the step S1 and the step S2, the rotation speed adopted by stirring is 300rpm-500rpm.
As a further preferred aspect of the present invention, in the step S1, the ratio of the amount mass of the reduced lead plaster to the amount volume of the iodized salt solution is 50g/L to 100g/L; the stirring reaction is carried out at 0-80 ℃.
In a further preferred aspect of the present invention, in the step S1, the iodized salt solution is at least one of a potassium iodide solution, a sodium iodide solution, and an ammonium iodide solution.
As a further preferred aspect of the present invention, in the step S3, the organic solvent is N, N-Dimethylformamide (DMF), or a mixed solution formed by mixing N, N-Dimethylformamide (DMF) and Dimethylsulfoxide (DMSO) in a volume ratio of 9:1 to 6:4.
As a further preferred aspect of the present invention, the volume fraction of the hydroiodic acid solution is 55 to 75%; the volume ratio of the hydriodic acid solution to the initial reaction solution is 0.5 mu L/mL-4 mu L/mL.
As a further preferred aspect of the present invention, in the step S3, the post-dissolution solid-liquid separation is performed at a heating temperature of 50 ℃ to 80 ℃;
in the step S4, the recrystallization is specifically cooling recrystallization, and the adopted temperature is-4-20 ℃.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
(1) The invention provides a short-process technology which can realize efficient and clean conversion from waste lead paste to high-purity lead iodide by using waste lead storage battery lead paste as a raw material. The existing process for converting the waste lead plaster into the lead iodide generally comprises at least five steps of desulfurization, reduction, acid leaching/alkaline precipitation, iodination, purification and the like in sequence, and the desulfurization and iodination processes are innovatively carried out by using the same reagent, so that the process is reduced to three steps (namely reduction, desulfurization and iodination and purification), and the input of chemical reagents is greatly reduced. Realizes the combination of the recycling of the waste lead acid storage battery and the preparation of lead iodide by a short-process wet method.
Lead iodide is an important industrial raw material, for example, it is an important raw material for preparing perovskite solar cell modules. The traditional preparation method comprises the steps of smelting and electrorefining primary lead (such as lead ore) to obtain lead ingots, obtaining lead solutions (such as lead acetate and lead nitrate) through acid solutions, and adding iodine-containing reagents (such as potassium iodide and hydroiodic acid) to obtain lead iodide. Wet preparation is generally carried out by desulfurizing and reducing regenerated lead (such as waste lead paste), leaching with acidic solution to obtain lead solution or precipitating with alkaline solution (such as sodium carbonate and sodium hydroxide), roasting to obtain lead oxide, and reacting with iodine-containing reagent to obtain lead iodide. The prior art relates to various reagent addition and lengthy reaction processes, and how to shorten the process flow and reduce the reagent addition is a great problem to be solved by the invention.
The invention uses the reduced lead plaster, the reduction treatment can be carried out according to the related prior art, the tetravalent lead dioxide in the waste lead plaster is reduced into bivalent lead, for example, the reduced lead plaster can be obtained by roasting the waste lead plaster in the waste lead acid storage battery at high temperature for reduction or adding H 2 O 2 Or lead plaster after reduction reaction of sulfite reducing agent, the main component of which comprises PbSO 4 PbO, metals Pb, pb (OH) 2 It is characterized by that it contains no tetravalent lead, only contains bivalent lead and simple substance of lead. In the prior art, alkaline reagents (such as sodium hydroxide and sodium carbonate) are required to be used for desulfurization, so that the lead plaster is convenient to be integrally converted into lead-containing solution for the next reaction. The invention innovatively proposes to react iodine-containing reagent with reduced lead plaster and utilize the solubility product of lead sulfate (1.6X10) -8 ) Is larger than lead iodide (7.47 multiplied by 10) -9 ) And (3) causing a precipitation conversion reaction to occur, thereby directly obtaining lead iodide from lead sulfate. The method of the invention can adopt NaI, KI, NH 4 Three common iodinated salts, as shown in figure 2 below, the reaction meets thermodynamic feasibility; compared with the prior art of directly using the reaction of the hydroiodic acid and Pb ions, the iodized salt has good stability and is more suitable for industrial application (the hydroiodic acid is easy to decompose and is unfavorable for industrial application).
The method of the invention also adjusts the pH value of the solution system by using the hydroiodic acid solution to ensure that the pH value is 2.0-6.0, and can effectively promote Pb ions to be PbI 2 In the form of (a) to increase lead conversion. As hereinafter3, figure 3 shows the presence of lead sulfate in potassium iodide solution at different pH, in particular: when the pH is more than 7.0, the lead component is formed as basic lead sulfate (PbO. PbSO) 4 ) And lead hydroxide (Pb (OH) 2 ) In the form of (2); and when the pH is less than 6, the lead component is formed as lead iodide (PbI) 2 ) And a small amount of lead sulfate (PbSO) 4 ) Is present in the form of (c). The invention achieves the aim of regulating the pH value by adding the hydroiodic acid, so that the pH value of a solution system can meet 2.0-6.0, and the hydroiodic acid can also reduce PbO and Pb (OH) in lead paste 2 The reaction thus increases lead conversion, improves final yield, and does not introduce new impurity ions. The chemical reactions occurring in the above process are as follows:
PbSO 4 +2I - ＝SO 4 2- +PbI 2 (1)
PbO+2HI＝H 2 O+PbI 2 (2)
Pb(OH) 2 +2HI＝2H 2 O+PbI 2 (3)
Pb+2HI＝H 2 +PbI 2 (4)
(2) Only two reagent emissions exist in the whole process, wherein sulfate solution generated in the desulfurization process can be recovered as a byproduct; the lead-containing solid produced in the process of leaching and recrystallizing with organic solvent can be used as raw material for next reaction, and the filtrate can be used as organic solvent for cyclic utilization (that is, the solid obtained in the solid-liquid separation process of step S4 of the method is high-purity lead iodide crystal, the obtained filtrate is organic solvent containing a small amount of lead iodide and can be circularly used in step S3, and the main solid component obtained in the solid-liquid separation process of step S3 is PbSO) 4 As one of the main components in the reduced lead plaster, the solid obtained in the solid-liquid separation process in step S3 may be reused as the reduced lead plaster in step S1, and for example, the solid may be mixed with the reduced lead plaster to be treated and then subjected to the next reaction. The process has less pollutant exhausted and less environmental pollution.
(3) According to the invention, only three chemical reagents of iodized salt solution, hydroiodic acid and organic solvent are added, wherein iodized salt provides an iodine source for lead iodide, and is an indispensable raw material in various processes; the hydroiodic acid is used for regulating the pH value and has small dosage; the organic solvent only contains a small amount of lead iodide in a dissolved state after recrystallization and filtration, and the purity and the yield of the next batch of products can not be influenced even if the organic solvent is continuously used as the solvent, so that the organic solvent can be recycled without loss in theory. The invention avoids using a large amount of strong acid and strong alkali reagents used in the prior art, and improves the overall economy and environmental friendliness of the process.
(4) The method has mild reaction conditions and high reaction efficiency. The reaction time of the 4 main steps can be preferably not more than 2 hours, so that the production efficiency is greatly improved. The reaction process does not use high-temperature, high-pressure, high-speed stirring and other reaction conditions, the maximum reaction temperature is not more than 80 ℃, and the process is simple and controllable.
(5) The present invention is particularly useful for separating lead iodide from lead sulfate by using the above-mentioned organic solvent, taking advantage of the characteristic that lead iodide can be dissolved in DMF (or a mixture of DMF and DMSO) organic solvent but lead sulfate cannot be dissolved. The lead iodide crystal obtained by the method has high purity, and the crystal size can be controlled by controlling the recrystallization process conditions, so that the method is beneficial to subsequent use. The yield of lead iodide in the process exceeds 95%, and unconverted 5% lead-containing component can enter the next reaction for recycling.
Due to PbSO in the waste lead plaster 4 Is the most highly abundant (typically greater than 60 wt.%), most difficult to chemically react, and generally requires a desulfurization step, the most effective of which is the use of alkaline agents to carry out the PbSO 4 To other substances susceptible to chemical reactions (e.g. Pb (OH) 2 、PbCO 3 ) Or using an acidic solution (e.g. acetic acid) to carry out the PbSO 4 Is converted into lead solution. Other prior researches and techniques do not consider the thought of using iodine-containing reagent as desulfurizing agent, and the invention innovatively uses the iodine-containing reagent to perform the reaction on PbSO 4 Directly converting, and controlling the dosage of the iodized salt to ensure that the molar ratio of iodide ions in the iodized salt solution to lead elements in the reduced lead plaster is 2:1-4:1 (avoiding the combination of excessive iodide ions and lead iodide to form [ PbI) 4 ] 2- Complex ions) to achieve the effect of shortening the reaction flow. Whereas desulfurization by direct use of iodized salt actually occursIs a precipitation transformation process, which is difficult to transform one precipitate into another completely, and often two precipitates coexist. Through intensive research and development, the invention determines that lead sulfate precipitate is easier to convert into lead iodide under an acidic condition (namely, the pH value is 2.0-6.0), and hydroiodic acid is used as a reagent for regulating the pH value, so that the concentration of iodide ions is increased on the basis that the solution is acidic, thereby being more beneficial to the generation of lead iodide.
In summary, the invention combines the desulfurization step and the iodination process, innovatively uses the iodination salt solution as the desulfurization reagent and the iodination reagent, avoids the great use of acid-base chemical reagents, and realizes the preparation of lead iodide crystals in a short process. The organic solvent used in the invention has no loss under ideal conditions, the added hydroiodic acid is used as a pH adjusting reagent, the consumption is small, the whole process does not use high-temperature, high-pressure, high-energy consumption and other process conditions, no lead-containing solution and solid waste are discharged, and the economic consumption and the environmental impact are controlled to the minimum level. The total lead yield of the invention exceeds 95%, and the preparation of high-purity lead iodide crystals by a short-process wet method is realized.
Drawings
Fig. 1 is a process flow chart of preparing lead iodide crystals by a wet short process of reducing lead plaster.
FIG. 2 is NaI, KI, NH 4 I thermodynamic parameters of the reaction in the course of the reaction with lead sulphate.
FIG. 3 is a graph showing the distribution pattern of the lead-containing component simulated by Medusa software under different pH conditions (total lead ion concentration of 0.5mol/L, total sulfate ion concentration of 0.5mol/L, total iodide ion concentration of 1.0mol/L, and total potassium ion concentration of 1.0 mol/L).
Fig. 4 is an XRD pattern of the crude crystals obtained during the procedure of example 1.
FIG. 5 shows the high purity PbI obtained in example 1 2 XRD pattern of the crystal.
FIG. 6 shows the high purity PbI obtained in example 1 2 SEM image of the crystal.
Detailed Description
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. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
In general, the method for preparing lead iodide crystals by reducing lead plaster in a wet short process comprises the following steps: s1: desulfurizing the reduced lead plaster by adding an iodized salt solution and preliminarily converting the reduced lead plaster into lead iodide to obtain a preliminary reaction solution; s2: dripping hydroiodic acid into the reaction system to regulate the pH value, promoting the conversion of lead sulfate, and obtaining lead iodide crude crystals after solid-liquid separation; s3: dissolving the crude crystals by using an organic solvent, and obtaining filtrate by solid-liquid separation as lead iodide organic solution (in addition, solid after solid-liquid separation can be repeatedly used in the step S2); s4: recrystallizing the filtrate to obtain high-purity lead iodide crystals (in addition, the organic solvent after solid-liquid separation can be returned to the step S3 for recycling).
Specifically, in steps S1 and S2: the iodine salt solution can be, for example, potassium iodide, sodium iodide or ammonium iodide, the molar ratio of iodine ions in the iodine salt solution to lead in the reduced lead plaster can be 2:1-4:1 (the corresponding volume ratio of the reduced lead plaster to the iodine salt solution can be 50g/L-100g/L, the specific dosage ratio can be determined by the lead content in the reduced lead plaster), when the concentration of the iodine salt solution is fixed, the higher the Pb content is, the lower the solid-to-liquid ratio is, the lead content of the reduced lead plaster is generally 68-85 wt%, and 68wt% corresponds to the extreme case that the reduced lead plaster is composed of lead sulfate), and the reaction can be stirred for 0.5-2 h at 0-80 ℃ to obtain a preliminary reaction solution. 55-75% of hydriodic acid may be added dropwise to the preliminary reaction solution to adjust the pH to 2.0-6.0, and generally, the amount may be 0.5. Mu.L/mL-4. Mu.L/mL (i.e., 0.5. Mu.L-4. Mu.L of hydriodic acid solution per mL of preliminary reaction solution). The reaction solution system may be reacted for 10min to 30min under stirring at 300rpm to 500rpm. After the reaction is finished, the solid-liquid separation can be carried out after the decompression filtration, the solid is coarse crystal, and the main components are lead iodide and lead sulfate; the filtrate is mainly sulfate solution, and can be subjected to harmless treatment.
In step S3: the organic solvent may be DMF or a mixed solvent of DMF and DMSO, because impurities such as Fe, ba, sb, etc. can be removed by using DMF. For example, the crude crystals can be dissolved in an organic solvent at a heating temperature of 50-80 ℃ and then subjected to solid-liquid separation; controlling the volume ratio of the mol number of the lead in the crystals to the organic solvent to be 0.8mol/L-1.4mol/L (namely, the adding volume of the organic solvent can be adjusted according to the lead content in the reduced lead plaster; after being filtered by an organic filter membrane, the solid is lead sulfate, and can be mixed with the raw material of the reduced lead plaster to enter the next round of reaction, so that the discharge of lead components is avoided, and the solution is an organic solution of complex lead iodide.
In step S4: the recrystallization can particularly adopt a cooling recrystallization method, lead iodide crystals are separated out again at the temperature of-4 ℃ to 20 ℃, and solid-liquid separation is carried out after filtration by an organic filter membrane. The solid is lead iodide crystal. The resulting crystals contained no other components and exhibited regular hexagonal prism sheets. Correspondingly, the filtrate is DMF (or a mixed solution of DMF and DMSO), a small amount of lead iodide possibly remains, the filtrate can be recycled for dissolution and recrystallization of crude crystals, and the solvent consumption is not existed in ideal conditions.
The following are specific examples, each of which satisfies the process flow diagram shown in fig. 1.
Example 1
(1) 10g of reduced lead plaster (lead content is 0.0397mol measured by a chemical titration method) which is roasted for 30min at 450 ℃ in an air atmosphere is taken and placed in 200mL of potassium iodide solution with the concentration of 0.4mol/L, the solid-liquid ratio is 50g/L, and the molar ratio of iodide ions to lead ions is about 2:1. Stirring and reacting for 1h at normal temperature, filtering and separating to obtain a primary reaction solution. The pH of the reaction solution was 7.4.
(2) To the preliminary reaction solution, hydroiodic acid of 55% by volume was added dropwise until the pH of the solution was in the range of 2.0 to 6.0. The volume of the hydroiodic acid added dropwise in this example was 200. Mu.L, and the final pH of the solution was 3.2. The reaction was carried out for 20 minutes under stirring at 400rpm, and solid-liquid separation was carried out by suction filtration, whereby 14.97g of crude crystals were obtained.
(3) The crude crystals were placed in 33mL of DMF solvent, and the concentration of lead in the solution was about 1.0mol/L (in this case, it was assumed that all of the crude crystals were lead iodide; the same applies hereinafter). Heating and dissolving at 60deg.C for 30min, and separating solid and liquid with organic filter membrane.
(4) Cooling and recrystallizing the filtrate at-4 ℃ and then carrying out solid-liquid separation by using an organic filter membrane, drying the obtained solid in an oven at 60 ℃ for 6 hours to obtain lead iodide crystals, wherein the product quality is 14.95g, and the total lead yield is 98.30% (the total lead yield is obtained by testing the actual content of lead in the reduced lead plaster by using a chemical titration method, and the step is obtained by assuming that all products are calculated by lead iodide; the same as follows).
Further, the crude crystal obtained in the step (2) of the above example was subjected to XRD detection, and the result is shown in FIG. 4. XRD detection is carried out on the lead iodide crystal obtained in the step (4), and the result is shown in figure 5. By comparing fig. 4 with fig. 5, it is not difficult to find that the main components in the crude crystal obtained in step (2) are lead iodide and lead sulfate; and in the final lead iodide crystal obtained in the step (4), pbSO 4 The impurities have almost completely disappeared and the crystals contain no other components.
Further, the lead iodide crystal obtained in the step (4) was subjected to SEM characterization, and as a result, as shown in fig. 6, it was in the form of regular hexagonal prism sheets, and the crystallinity was good.
Example 2
(1) 10g of reduced lead plaster (lead content is 0.0397mol measured by a chemical titration method) baked for 30min at 450 ℃ in an air atmosphere is taken and placed in 100mL of sodium iodide solution with the concentration of 0.8mol/L, the solid-liquid ratio is 100g/L, and the molar ratio of iodide ions to lead ions is about 2:1. Stirring and reacting for 1h at normal temperature, filtering and separating to obtain a primary reaction solution. The pH of the reaction solution was 7.8.
(2) To the preliminary reaction solution, hydroiodic acid of 55% by volume was added dropwise until the pH of the solution was in the range of 2.0 to 6.0. The volume of the hydroiodic acid added dropwise in this example was 100. Mu.L, and the final pH of the solution was 2.8. The reaction was carried out for 20 minutes under stirring at 400rpm, and solid-liquid separation was carried out by suction filtration, whereby 14.80g of crude crystals were obtained.
(3) The crude crystals were placed in 30mL of DMF solvent, and the concentration of lead in the solution was about 1.1mol/L. Heating and dissolving at 60deg.C for 30min, and separating solid and liquid with organic filter membrane.
(4) Cooling and recrystallizing the filtrate at-4 ℃, then carrying out solid-liquid separation by using an organic filter membrane, and drying the obtained solid in a baking oven at 60 ℃ for 6 hours to obtain lead iodide crystals, wherein the product quality is 14.71g, and the total lead yield is 96.70%.
Example 3
(1) 10g of reduced lead plaster (lead content is 0.0374mol measured by a chemical titration method) baked for 15min at 450 ℃ in an air atmosphere is taken and placed in 150mL of ammonium iodide solution with the concentration of 0.5mol/L, the solid-liquid ratio is 67g/L, and the molar ratio of iodide ions to lead ions is about 2:1. Stirring and reacting for 1.5h at normal temperature, filtering and separating to obtain a primary reaction solution. The pH of the reaction solution was 7.3.
(2) To the preliminary reaction solution, hydroiodic acid of 55% by volume was added dropwise until the pH of the solution was in the range of 2.0 to 6.0. The volume of the hydroiodic acid added dropwise in this example was 60. Mu.L, and the final pH of the solution was 5.9. The reaction was carried out for 20 minutes under stirring at 400rpm, and solid-liquid separation was carried out by suction filtration, whereby 14.81g of crude crystals were obtained.
(3) The crude crystals were placed in 30mL of DMF: dmso=7:3 (volume ratio) solvent, the concentration of lead in the solution being about 1.1mol/L. Heating and dissolving at 60deg.C for 30min, and separating solid and liquid with organic filter membrane.
(4) Cooling and recrystallizing the filtrate at-4 ℃ and then carrying out solid-liquid separation by using an organic filter membrane, and drying the obtained solid in a drying oven at 60 ℃ for 6 hours to obtain lead iodide crystals, wherein the product quality is 14.57g, and the total lead yield is 96.07%.
Example 4
(1) 5g of reduced lead plaster (lead content is 0.0196mol measured by a chemical titration method) which is reacted with a hydrogen peroxide solution is taken and placed in 100mL of potassium iodide solution with concentration of 0.4mol/L, the solid-liquid ratio is 50g/L, and the molar ratio of iodide ions to lead ions is about 2:1. Stirring and reacting for 2h at normal temperature, filtering and separating to obtain a primary reaction solution. The pH of the reaction solution was 7.3.
(2) To the preliminary reaction solution, hydroiodic acid of 55% by volume was added dropwise until the pH of the solution was in the range of 2.0 to 6.0. The volume of the hydroiodic acid added dropwise in this example was 50. Mu.L, and the final pH of the solution was 5.3. The reaction was carried out for 10 minutes under stirring at 400rpm, and solid-liquid separation was carried out by suction filtration, whereby 7.36g of crude crystals were obtained.
(3) The crude crystals were placed in 12mL of DMF: dmso=9:1 (volume ratio) solvent, the concentration of lead in the solution being about 1.37mol/L. Heating and dissolving at 80deg.C for 20min, and separating solid and liquid with organic filter membrane.
(4) Cooling and recrystallizing the filtrate at-4 ℃ and then carrying out solid-liquid separation by using an organic filter membrane, and drying the obtained solid in a drying oven at 60 ℃ for 6 hours to obtain lead iodide crystals, wherein the product quality is 7.34g and the total lead yield is 96.51%.
Example 5
(1) 20g of reduced lead plaster (lead content is 0.0787mol measured by a chemical titration method) which is reacted with a hydrogen peroxide solution is taken and placed in 200mL of potassium iodide solution with concentration of 0.8mol/L, the solid-liquid ratio is 100g/L, and the molar ratio of iodide ions to lead ions is about 2:1. Stirring and reacting for 2h at normal temperature, filtering and separating to obtain a primary reaction solution. The pH of the reaction solution was 7.8.
(2) To the preliminary reaction solution, hydroiodic acid of 55% by volume was added dropwise until the pH of the solution was in the range of 2.0 to 6.0. The volume of the hydroiodic acid added dropwise in this example was 200. Mu.L, and the final pH of the solution was 3.6. The reaction was carried out for 30 minutes under stirring at 500rpm, and solid-liquid separation was carried out by suction filtration, whereby 29.48g of crude crystals were obtained.
(3) The crude crystals were placed in 60mL of DMF solvent, and the concentration of lead in the solution was about 1.1mol/L. Heating and dissolving at 60deg.C for 30min, and separating solid and liquid with organic filter membrane.
(4) Cooling and recrystallizing the filtrate at-4 ℃ and then carrying out solid-liquid separation by using an organic filter membrane, and drying the obtained solid in a baking oven at 60 ℃ for 6 hours to obtain lead iodide crystals, wherein the product quality is 29.24g, and the total lead yield is 96.11%.
Example 6
(1) 10g of reduced lead plaster (lead content is 0.0397mol measured by a chemical titration method) which is roasted for 30min at 450 ℃ in an air atmosphere is taken and placed in 200mL of potassium iodide solution with the concentration of 0.8mol/L, the solid-liquid ratio is 50g/L, and the molar ratio of iodide ions to lead ions is about 4:1. Stirring and reacting for 1h at normal temperature, filtering and separating to obtain a primary reaction solution. The pH of the reaction solution was 7.9.
(2) To the preliminary reaction solution, hydroiodic acid of 55% by volume was added dropwise until the pH of the solution was in the range of 2.0 to 6.0. The volume of the hydroiodic acid added dropwise in this example was 400. Mu.L, and the final pH of the solution was 2.0. The reaction was carried out for 20 minutes under stirring at 400rpm, and solid-liquid separation was carried out by suction filtration, whereby 14.75g of crude crystals were obtained.
(3) The crude crystals were placed in 33mL of DMF: dmso=6:4 (volume ratio) solvent, and the concentration of lead in the solution was about 1.0mol/L (in this case, it was assumed that all of the crude crystals were lead iodide; the same applies hereinafter). Heating and dissolving at 60deg.C for 30min, and separating solid and liquid with organic filter membrane.
(4) Cooling and recrystallizing the filtrate at-4 ℃ and then carrying out solid-liquid separation by using an organic filter membrane, and drying the obtained solid in a baking oven at 60 ℃ for 6 hours to obtain lead iodide crystals, wherein the product quality is 14.53g, and the total lead yield is 95.81%.
Table 1 comparison of parameter conditions and total lead yield results for examples 1-6
Comparative example 1
(1) 10g of reduced lead plaster (lead content is 0.0397mol measured by a chemical titration method) baked for 30min at 450 ℃ in an air atmosphere is taken and placed in 100mL of potassium iodide solution with the concentration of 0.8mol/L, the solid-liquid ratio is 100g/L, and the molar ratio of iodide ions to lead ions is about 2:1. Stirring and reacting for 1h at normal temperature, filtering and separating to obtain a primary reaction solution. The pH of the reaction solution was 7.7.
(2) The pH was adjusted without using hydroiodic acid, and solid-liquid separation was performed by direct suction filtration to give 13.21g of crude crystals.
(3) The crude crystals were placed in 30mL of DMF solvent, and the concentration of lead in the solution was about 0.6mol/L. Heating and dissolving at 60deg.C for 30min, and separating solid and liquid with organic filter membrane.
(4) Cooling and recrystallizing the filtrate at-4 ℃ and then carrying out solid-liquid separation by using an organic filter membrane, and drying the obtained solid in a baking oven at 60 ℃ for 6 hours to obtain lead iodide crystals, wherein the product quality is 8.33g, and the total lead yield is 63.70%.
Comparative example 2
(1) 10g of reduced lead plaster (lead content is 0.0397mol measured by a chemical titration method) baked for 30min at 450 ℃ in an air atmosphere is taken and placed in 200mL of potassium iodide solution with the concentration of 1.4mol/L, the solid-liquid ratio is 100g/L, and the molar ratio of iodide ions to lead ions is about 7:1. Stirring and reacting for 1h at normal temperature, filtering and separating to obtain a primary reaction solution. The pH of the reaction solution was 8.3.
(2) To the preliminary reaction solution, hydroiodic acid of 55% by volume was added dropwise until the pH of the solution was in the range of 2.0 to 6.0. The volume of the hydroiodic acid added dropwise in this example was 200. Mu.L, and the final pH of the solution was 3.7. The reaction was carried out for 20 minutes under stirring at 400rpm, and solid-liquid separation was carried out by suction filtration, whereby 13.63g of crude crystals were obtained.
(3) The crude crystals were placed in 30mL of DMF solvent, and the concentration of lead in the solution was about 0.9mol/L. Heating and dissolving at 60deg.C for 30min, and separating solid and liquid with organic filter membrane.
(4) Cooling and recrystallizing the filtrate at-4 ℃, then carrying out solid-liquid separation by using an organic filter membrane, and drying the obtained solid in a baking oven at 60 ℃ for 6 hours to obtain lead iodide crystals, wherein the product quality is 13.01g, and the total lead yield is 87.32%.
This comparative example is due to the use of an excess of iodinated salt solution (excess iodide ions combine with lead iodide to form [ PbI ] 4 ] 2- Complex ions), leading to dissolution of lead iodide and reduced yields.
Comparative example 3
(1) 10g of reduced lead plaster (lead content is 0.0397mol measured by a chemical titration method) baked for 30min at 450 ℃ in an air atmosphere is taken and placed in 100mL of potassium iodide solution with the concentration of 0.8mol/L, the solid-liquid ratio is 100g/L, and the molar ratio of iodide ions to lead ions is about 2:1. Stirring and reacting for 1h at normal temperature, filtering and separating to obtain a primary reaction solution. The pH of the reaction solution was 7.8.
(2) To the preliminary reaction solution, hydroiodic acid of 55% by volume was added dropwise until the pH of the solution was in the range of 2.0 to 6.0. The volume of the hydroiodic acid added dropwise in this example was 200. Mu.L, and the final pH of the solution was 3.3. The reaction was carried out for 20 minutes under stirring at 400rpm, and solid-liquid separation was carried out by suction filtration, whereby 14.66g of crude crystals were obtained.
(3) The product components were tested directly as a mixture of lead iodide and lead sulfate, with lead iodide accounting for 95.23% and the remainder as lead sulfate impurities.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (9)
1. The method for preparing the lead iodide crystal by reducing the lead plaster through a wet short process is characterized by comprising the following steps of:
s1: collecting waste lead paste in the waste lead acid storage battery and carrying out reduction treatment to obtain reduced lead paste without +4-valent Pb element; then, placing the reduced lead plaster in an iodized salt solution, wherein the molar ratio of iodide ions in the iodized salt solution to lead elements in the reduced lead plaster is 2:1-4:1; then, stirring and reacting for 0.5-2 h to obtain a primary reaction solution;
s2: adding a hydriodic acid solution into the primary reaction solution obtained in the step S1, regulating the pH value to 2.0-6.0, and fully reacting and then carrying out solid-liquid separation; the solid obtained by the solid-liquid separation is coarse crystal;
s3: placing the crude crystal obtained in the step S2 into an organic solvent for dissolution and then carrying out solid-liquid separation; the filtrate obtained by the solid-liquid separation is lead iodide solution;
s4: recrystallizing the lead iodide solution obtained in the step S3, and then carrying out solid-liquid separation; the solid obtained by solid-liquid separation is the purified lead iodide crystal.
2. The method of claim 1, wherein,in the step S1, the reduced lead plaster is obtained by roasting and reducing waste lead plaster in a lead-acid storage battery at a high temperature or performing a reduction reaction with a reducing agent; wherein the temperature adopted by the high-temperature roasting reduction is 300-600 ℃, and the atmosphere adopted by the high-temperature roasting reduction is air and N 2 Or an inert gas, more preferably argon; the reducing agent is H 2 O 2 Or sulfite, more preferably Na 2 SO 3 。
3. The method of claim 1, wherein the solid obtained by the solid-liquid separation in the step S3 can be reused as a reduced lead paste in the step S1;
the filtrate obtained by the solid-liquid separation in the step S4 can be used as an organic solvent to be repeatedly used in the step S3.
4. The method according to claim 1, wherein in step S2, the reaction is in particular a stirred reaction for 10min to 30min;
in the step S1 and the step S2, the rotation speed adopted by stirring is 300rpm-500rpm.
5. The method according to claim 1, wherein in the step S1, the ratio of the amount mass of the reduced lead plaster to the amount volume of the iodized salt solution is 50g/L to 100g/L; the stirring reaction is carried out at 0-80 ℃.
6. The method of claim 1, wherein in step S1, the iodized salt solution is at least one of a potassium iodide solution, a sodium iodide solution, and an ammonium iodide solution.
7. The method according to claim 1, wherein in the step S3, the organic solvent is N, N-Dimethylformamide (DMF), or a mixed solution formed by mixing N, N-Dimethylformamide (DMF) with Dimethylsulfoxide (DMSO) in a volume ratio of 9:1 to 6:4.
8. The method of claim 1, wherein in step S2, the hydroiodic acid solution has a volume fraction of 55-75%; the volume ratio of the hydriodic acid solution to the initial reaction solution is 0.5 mu L/mL-4 mu L/mL.
9. The method according to claim 1, wherein in the step S3, the post-dissolution solid-liquid separation is performed at a heating temperature of 50 ℃ to 80 ℃;
in the step S4, the recrystallization is specifically cooling recrystallization, and the adopted temperature is-4-20 ℃.
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