CN116770415A - Method for preparing lead chloride crystal by waste lead plaster wet method short process - Google Patents
Method for preparing lead chloride crystal by waste lead plaster wet method short process Download PDFInfo
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- CN116770415A CN116770415A CN202310804895.3A CN202310804895A CN116770415A CN 116770415 A CN116770415 A CN 116770415A CN 202310804895 A CN202310804895 A CN 202310804895A CN 116770415 A CN116770415 A CN 116770415A
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- HWSZZLVAJGOAAY-UHFFFAOYSA-L lead(II) chloride Chemical compound Cl[Pb]Cl HWSZZLVAJGOAAY-UHFFFAOYSA-L 0.000 title claims abstract description 96
- 238000000034 method Methods 0.000 title claims abstract description 96
- 239000002699 waste material Substances 0.000 title claims abstract description 91
- 239000011505 plaster Substances 0.000 title claims abstract description 83
- 230000008569 process Effects 0.000 title claims abstract description 53
- 239000013078 crystal Substances 0.000 title claims abstract description 49
- 239000000243 solution Substances 0.000 claims abstract description 112
- 238000002386 leaching Methods 0.000 claims abstract description 99
- 239000007788 liquid Substances 0.000 claims abstract description 59
- FAPWRFPIFSIZLT-UHFFFAOYSA-M sodium chloride Inorganic materials [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 55
- 238000006243 chemical reaction Methods 0.000 claims abstract description 52
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims abstract description 40
- 238000006477 desulfuration reaction Methods 0.000 claims abstract description 37
- 230000023556 desulfurization Effects 0.000 claims abstract description 37
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 34
- 239000011780 sodium chloride Substances 0.000 claims abstract description 34
- 238000003756 stirring Methods 0.000 claims abstract description 32
- 238000001953 recrystallisation Methods 0.000 claims abstract description 16
- 239000011259 mixed solution Substances 0.000 claims abstract description 12
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 66
- 239000007787 solid Substances 0.000 claims description 41
- 239000000706 filtrate Substances 0.000 claims description 37
- 238000000926 separation method Methods 0.000 claims description 28
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 16
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 13
- 238000001816 cooling Methods 0.000 claims description 13
- 238000010438 heat treatment Methods 0.000 claims description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 13
- 239000012633 leachable Substances 0.000 claims description 3
- 239000002253 acid Substances 0.000 abstract description 16
- 239000003153 chemical reaction reagent Substances 0.000 abstract description 15
- 238000002360 preparation method Methods 0.000 abstract description 11
- 238000004064 recycling Methods 0.000 abstract description 8
- 238000003860 storage Methods 0.000 abstract description 8
- 238000013461 design Methods 0.000 abstract description 2
- 239000000047 product Substances 0.000 description 32
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 27
- 239000012535 impurity Substances 0.000 description 21
- 238000000967 suction filtration Methods 0.000 description 18
- 229910052742 iron Inorganic materials 0.000 description 16
- HTUMBQDCCIXGCV-UHFFFAOYSA-N lead oxide Chemical compound [O-2].[Pb+2] HTUMBQDCCIXGCV-UHFFFAOYSA-N 0.000 description 14
- PIJPYDMVFNTHIP-UHFFFAOYSA-L lead sulfate Chemical compound [PbH4+2].[O-]S([O-])(=O)=O PIJPYDMVFNTHIP-UHFFFAOYSA-L 0.000 description 14
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 description 13
- 239000001099 ammonium carbonate Substances 0.000 description 13
- 235000012501 ammonium carbonate Nutrition 0.000 description 12
- YADSGOSSYOOKMP-UHFFFAOYSA-N dioxolead Chemical compound O=[Pb]=O YADSGOSSYOOKMP-UHFFFAOYSA-N 0.000 description 12
- 238000001914 filtration Methods 0.000 description 11
- 238000002425 crystallisation Methods 0.000 description 10
- 239000002994 raw material Substances 0.000 description 10
- 230000008025 crystallization Effects 0.000 description 9
- 238000001035 drying Methods 0.000 description 9
- MFEVGQHCNVXMER-UHFFFAOYSA-L 1,3,2$l^{2}-dioxaplumbetan-4-one Chemical compound [Pb+2].[O-]C([O-])=O MFEVGQHCNVXMER-UHFFFAOYSA-L 0.000 description 8
- 229910000003 Lead carbonate Inorganic materials 0.000 description 8
- 229910052751 metal Inorganic materials 0.000 description 8
- 239000002184 metal Substances 0.000 description 8
- 230000002829 reductive effect Effects 0.000 description 8
- 239000000460 chlorine Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 239000006227 byproduct Substances 0.000 description 6
- 229910000464 lead oxide Inorganic materials 0.000 description 6
- 239000012046 mixed solvent Substances 0.000 description 6
- 229910052788 barium Inorganic materials 0.000 description 5
- 238000005660 chlorination reaction Methods 0.000 description 5
- 230000003009 desulfurizing effect Effects 0.000 description 5
- 238000005265 energy consumption Methods 0.000 description 5
- 238000011084 recovery Methods 0.000 description 5
- 239000011734 sodium Substances 0.000 description 5
- 238000002441 X-ray diffraction Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 3
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 3
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 3
- 239000001110 calcium chloride Substances 0.000 description 3
- 229910001628 calcium chloride Inorganic materials 0.000 description 3
- 229910001424 calcium ion Inorganic materials 0.000 description 3
- 239000003638 chemical reducing agent Substances 0.000 description 3
- 150000003841 chloride salts Chemical class 0.000 description 3
- 150000001804 chlorine Chemical class 0.000 description 3
- 229910052801 chlorine Inorganic materials 0.000 description 3
- 239000012043 crude product Substances 0.000 description 3
- 238000011161 development Methods 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000012266 salt solution Substances 0.000 description 3
- 230000001360 synchronised effect Effects 0.000 description 3
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- 239000012445 acidic reagent Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000003344 environmental pollutant Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 229940046892 lead acetate Drugs 0.000 description 2
- 231100000719 pollutant Toxicity 0.000 description 2
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 2
- 238000013088 quantum-dot photovoltaic Methods 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000007790 solid phase Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 238000004448 titration Methods 0.000 description 2
- 239000002912 waste gas Substances 0.000 description 2
- -1 wherein Chemical compound 0.000 description 2
- 229910000013 Ammonium bicarbonate Inorganic materials 0.000 description 1
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 1
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 235000012538 ammonium bicarbonate Nutrition 0.000 description 1
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical group N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 1
- 229910052921 ammonium sulfate Inorganic materials 0.000 description 1
- 235000011130 ammonium sulphate Nutrition 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910001422 barium ion Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 239000012320 chlorinating reagent Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 229910021419 crystalline silicon Inorganic materials 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000009775 high-speed stirring Methods 0.000 description 1
- JWZCKIBZGMIRSW-UHFFFAOYSA-N lead lithium Chemical compound [Li].[Pb] JWZCKIBZGMIRSW-UHFFFAOYSA-N 0.000 description 1
- AGMMPPVVMLRYIL-UHFFFAOYSA-L lead(2+);chloride;hydroxide Chemical compound [OH-].[Cl-].[Pb+2] AGMMPPVVMLRYIL-UHFFFAOYSA-L 0.000 description 1
- XCAUINMIESBTBL-UHFFFAOYSA-N lead(ii) sulfide Chemical compound [Pb]=S XCAUINMIESBTBL-UHFFFAOYSA-N 0.000 description 1
- YWCLWGMTGGFSDF-UHFFFAOYSA-N lead;dihydrate Chemical compound O.O.[Pb] YWCLWGMTGGFSDF-UHFFFAOYSA-N 0.000 description 1
- 229910001416 lithium ion Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000010587 phase diagram Methods 0.000 description 1
- 229910000027 potassium carbonate Inorganic materials 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 238000009853 pyrometallurgy Methods 0.000 description 1
- 239000002096 quantum dot Substances 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 239000012265 solid product Substances 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B7/00—Single-crystal growth from solutions using solvents which are liquid at normal temperature, e.g. aqueous solutions
- C30B7/14—Single-crystal growth from solutions using solvents which are liquid at normal temperature, e.g. aqueous solutions the crystallising materials being formed by chemical reactions in the solution
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B28/00—Production of homogeneous polycrystalline material with defined structure
- C30B28/04—Production of homogeneous polycrystalline material with defined structure from liquids
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/12—Halides
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention belongs to the technical field of recycling of waste lead acid storage batteries and preparation of lead chloride crystals, and discloses a method for preparing lead chloride crystals by a waste lead plaster wet method in a short process, which comprises the following steps: s1: placing the waste lead plaster into carbonate solution for stirring reaction to obtain desulfurized lead plaster; s2: taking HCl-NaCl mixed solution as a leaching agent, and carrying out leaching reaction on the desulfurization lead plaster to obtain leaching liquid; s3: and recrystallizing to obtain lead chloride crystals. According to the invention, the whole flow process design of the preparation method is improved, the waste lead plaster is firstly subjected to desulfurization treatment by using a carbonate solution, then the leaching reaction is carried out by using an HCl-NaCl mixed solution as a leaching agent and the desulfurization lead plaster, and finally, the high-purity lead chloride crystal is obtained by recrystallization, so that the technical problems of long process steps, large reagent input and low lead chloride conversion rate in the prior art are effectively solved.
Description
Technical Field
The invention belongs to the technical field of recycling of waste lead acid storage batteries and preparation of lead chloride crystals, and particularly relates to a method for preparing lead chloride crystals by a waste lead paste wet method in a short process.
Background
Lead chloride is one of the most important raw materials in the preparation process of lead-based perovskite solar cells and PbS quantum dot materials. Along with the rapid development of photovoltaic devices, pbS quantum dot photovoltaic devices have the outstanding advantages of high efficiency, light weight, simple manufacturing process, capability of being prepared into large-area flexible devices and the like, but compared with the prior art of leading crystalline silicon photovoltaic devices, the PbS quantum dot photovoltaic devices are still higher in manufacturing cost, and the problem of expensive raw materials is solved by low-cost high-purity lead chloride. At present, the preparation process of commercial lead chloride raw materials is to react lead carbonate, lead oxide or lead acetate with hydrochloric acid to obtain lead chloride, 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, rapid development of lithium ion batteries has led to certain replacement of lead-acid batteries for consumption, resulting in reduced lead requirements. At present, the trend of 'lead lithium removal in' is obvious, lead consumption is influenced by substitution, the market application market in the consumption field is atrophic, and the regenerated lead market using a lead-acid storage battery as a main product faces challenges.
The waste lead plaster is mainly obtained by crushing and screening the lead-acid storage batteryA secondary lead raw material comprising PbSO as a main component 4 、PbO 2 PbO, pb, and a small amount of Fe, ba, and other metallic impurities. At present, the traditional pyrometallurgy technology for recycling waste lead acid storage batteries is extremely easy to cause SO 2 The emission of acid gas, and the volatilization product of lead at high temperature are also a hazard to human body and serious pollutant. While the wet recovery process reduces the energy consumption and lead and waste gas pollution to a great extent, the problems of complex process (steps such as desulfurization, reduction, leaching, precipitation and the like are needed to be sequentially carried out), high energy consumption, high cost, serious electrolyte pollution and the like still exist. Therefore, if the short-process wet recovery of the high-purity lead chloride product of the waste lead paste can be realized, the green high-quality development of the regenerated lead industry can be effectively promoted, and a new target is provided for the supply direction of the regenerated lead.
The invention discloses a process for recycling lead paste of a waste lead acid battery by using a vacuum chlorination method, which comprises the steps of reducing lead dioxide in the lead paste into lead oxide by vacuum roasting, mixing the lead oxide with a chlorinating agent for vacuum chlorination, volatilizing the lead oxide, condensing and crystallizing the lead oxide to obtain a lead chloride crude product. CN202110909314.3 and CN201510935345.0 disclose a method for recovering lead chloride from lead waste residue, which comprises calcining and acid leaching to obtain lead-containing reagent, adding excessive chlorine-containing reagent to synthesize lead chloride, and the whole process comprises high-temperature calcining-acid leaching-chloridizing synthesis and other complex processes, and has high energy consumption and difficult pollution control. CN201911191909.9 and cn201010211871.X disclose a direct leaching of waste lead paste using chloride salts, such leaching being due to the solubility product of lead chloride (2 x 10) -5 ) Is larger than lead sulfate (1.6X10) -8 ) Therefore, excessive hydrochloric acid (for example, the weight ratio of the lead plaster to the saturated sodium chloride solution is 1:13-15, and the weight ratio of the lead plaster to the 37% hydrochloric acid solution is 1:2-2.5) is needed to be added into the chloride salt solution, and the mixture is cooled and crystallizedSulfate byproducts exist in the crystallization filtrate after lead chloride is formed, calcium chloride is added for treatment and then the crystallization filtrate can be recycled, and unreacted calcium ions in the step accumulate in the filtrate to influence the recycling leaching effect; and a reducing agent is added in the leaching process for treating the lead dioxide in the waste lead plaster.
In summary, the existing lead chloride preparation process flows have the problems of large energy consumption, large reagent addition amount, unstable filtrate circulation treatment method and low lead chloride conversion rate, and the migration and conversion of main impurities such as Fe, ba and the like in the waste lead paste are not clearly analyzed, so that a new short-flow wet process from the waste lead paste to high-purity lead chloride needs to be developed.
Disclosure of Invention
Aiming at the defects or improvement demands of the prior art, the invention aims to provide a method for preparing lead chloride crystals by a waste lead plaster wet method short process, wherein the technical problems of long process steps, large reagent input and low lead chloride conversion rate in the prior art are effectively solved by improving the overall process design of the preparation method, firstly, carrying out desulfurization treatment on the waste lead plaster by using a carbonate solution, then, carrying out leaching reaction with the desulfurization lead plaster by using an HCl-NaCl mixed solution as a leaching agent, and finally, recrystallizing to obtain the high-purity lead chloride crystals. The method has the advantages of small addition amount of the reagent used in the technical process, high conversion rate, low impurity content and few byproducts, and realizes the short-process clean conversion from waste lead paste to high-purity lead chloride. In addition, the solution containing chloride ions (i.e. the leaching agent) can be subjected to 100% closed circulation to the next leaching process of the desulfurization lead plaster, and the resource utilization rate is high.
In order to achieve the above object, according to the present invention, there is provided a method for preparing lead chloride crystals in a short wet process of waste lead paste, characterized by comprising the steps of:
s1: placing the waste lead plaster into carbonate solution, stirring and reacting for at least 1h, and then carrying out solid-liquid separation, wherein the solid obtained by the solid-liquid separation is the desulfurization lead plaster; wherein the molar ratio of carbonate ions in the carbonate solution to sulfate ions in the waste lead paste is greater than or equal to 1:1;
s2: taking HCl-NaCl mixed solution as a leaching agent, placing the desulfurization lead plaster obtained in the step S1 into the leaching agent, carrying out leaching reaction for at least 2 hours at the temperature of 70-90 ℃, and then carrying out solid-liquid separation to obtain filtrate; wherein the pH of the leachable agent is no more than 2.0;
s3: and (3) recrystallizing the filtrate obtained in the step (S2) and then carrying out solid-liquid separation, wherein the solid obtained by the solid-liquid separation is lead chloride crystals.
As a further preferred aspect of the present invention, in the step S3, the recrystallization is specifically a recrystallization by cooling;
preferably, the filtrate obtained by the solid-liquid separation can be used as a leaching agent and repeatedly used in the step S2;
more preferably, the temperature adopted by the cooling recrystallization is between-20 ℃ and-4 ℃.
As a further preferred aspect of the present invention, in the step S2, the concentration of chloride ions in the leaching agent is not less than 4.32mol/L;
preferably, the pH value of the leaching agent is 1.0-2.0; the concentration of chloride ions in the leaching agent is 4.32mol/L-5.19mol/L; the solid-liquid ratio of the desulfurization lead plaster to the leaching agent is 30g/L-40g/L; more preferably, the HCl-NaCl mixed solution is obtained by dropping 37-38% hydrochloric acid into a sodium chloride solution with a concentration of 250g/L to 300g/L to adjust the pH of the system to 1.0-2.0.
As a further preferred aspect of the present invention, in the step S1, the carbonate ion concentration in the carbonate solution is 0.36mol/L to 0.29mol/L, and the ratio of the mass of the waste lead plaster to the volume of the carbonate solution is 100g/L to 125g/L.
As a further preferred aspect of the present invention, in the step S1, a molar ratio of carbonate ions in the carbonate solution to sulfate ions in the waste lead paste is 1.2:1 or more; preferably, the molar ratio of carbonate ions in the carbonate solution to sulfate ions in the waste lead paste is 1.2:1-1.4:1;
the stirring reaction is carried out at the temperature of 35-55 ℃; preferably, the temperature condition of 35 ℃ to 55 ℃ is provided by water bath heating.
As a further preferred aspect of the present invention, in the step S1, the stirring speed used for the stirring reaction is 300rpm to 500rpm.
As a further preferred aspect of the present invention, in the step S2, the temperature condition of 70 ℃ to 90 ℃ is provided by heating in a water bath.
As a further preferred aspect of the present invention, in the step S2, the leaching reaction is performed under stirring at a stirring speed of 300rpm to 500rpm.
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 chloride by using waste lead storage battery lead paste as a raw material. The existing wet conversion process of waste lead plaster to lead chloride generally directly adopts a chloride method for leaching, and has the problems that the adding amount of reagents is large, filtrate can be recycled after being treated, and the lead chloride conversion rate is low (about 85 percent). The invention improves the process flow, firstly carries out desulfurization pretreatment on the waste lead paste, converts lead sulfate into lead carbonate which is easier to react with chlorine salt solution, and can greatly improve the conversion rate (namely, the recovery rate) of lead; and, by using HCl-NaCl mixed solution as leaching agent, leaching reaction is carried out with the desulfurization lead plaster under the temperature condition of 70-90 ℃, especially for the refractory +4 valent lead (namely PbO 2 ) Synchronous reduction and chlorination can be realized in HCl-NaCl solution, and the technical problem that reducing agents such as methanol, iron powder and the like are needed to be added is solved. In addition, by utilizing the method, fe, ba and other impurities in the waste lead paste are kept in the solid-phase waste residue in the middle step in the whole recovery process, so that the conversion of high-purity lead chloride is realized.
Lead chloride is an important raw material for preparing PbS quantum dots, and is usually lead chloride with purity of more than 99.9 percent and high price. The traditional analytical pure medicine preparation method is to react lead carbonate, lead oxide or lead acetate with hydrochloric acid to obtain lead chloride. The wet recovery process for preparing lead chloride is to reduce the waste lead paste by roasting or adding oxidant, leach with chloride solution, cool and recrystallize to obtain lead chloride. The existing technology needs to add a large amount of hydrochloric acid to synchronously treat the lead sulfate in the waste lead plaster, and the filtrate can be recycled by additionally adding a reagent, so that how to reduce the adding amount of the acid reagent of the technology, improve the lead chloride conversion rate and reduce the uncontrollable influence in the filtrate recycling process is a problem which is solved in an important way.
The waste lead paste is obtained by crushing and splitting waste lead acid storage batteries, and comprises the main components of PbSO 4 、PbO 2 PbO, metal Pb, and small amounts of other metallic impurities. Among the more difficult components to handle are lead sulfate and tetravalent lead. The invention uses carbonate to desulfurate the waste lead plaster, so that lead sulfate in the waste lead plaster is converted into lead carbonate which is easy to react with acid. In the case of tetravalent lead, however, the tetravalent lead is required in the prior art by pyrolysis at high temperatures or addition of H 2 O 2 、Na 2 SO 3 And reducing with a reducing agent. The invention realizes synchronous reductive chlorination (shown as reaction formulas (2) to (6) below) by firstly desulfurizing the waste lead plaster and then using chlorine salt leaching reaction. The invention can effectively reduce the acid addition amount of the whole process and improve the final yield by firstly converting the lead sulfate into the lead carbonate which is easier to react with the hydrochloric acid. In addition, the lead chloride crystals can be recrystallized by adopting cooling recrystallization, and the lead chloride crystals can be directly used without treating recycled filtrate (namely, the solid obtained by solid-liquid separation after cooling recrystallization is high-purity lead chloride crystals, the filtrate is filtrate containing chloride salt and can be reused as a leaching agent in the method of the invention to realize recycling, and specifically, the filtrate contains NaCl, HCl and a small amount of dissolved lead chloride and NaPbCl) 3 And Na (Na) 2 PbCl 4 The pH value of the mixed solvent is basically the same as that of the leaching agent before leaching reaction, and the mixed solvent does not need to be regulated again, so that the mixed solvent can be circularly used for leaching reaction; if the pH value of the leaching agent is changed and the condition that the pH value is not more than or equal to 2.0 is not met after the leaching agent is recycled for a plurality of times, the pH value of the leaching agent can be adjusted by using the originally prepared HCl-NaCl mixed solution.
Taking ammonium carbonate as an example of a desulfurizing agent, a chemical reaction occurring in the desulfurizing process is represented by the following formula (1).
PbSO 4 +(NH 4 ) 2 CO 3 ＝(NH 4 ) 2 SO 4 +PbCO 3 (1)
The ammonium carbonate content used for desulfurization can be calculated according to the lead sulfate content in the waste lead plaster, and the molar ratio of carbonate ions to sulfate ions in the waste lead plaster is required to be more than or equal to 1:1. In order to ensure sufficient desulfurization, the molar ratio of carbonate ions to sulfate ions in the waste lead paste can be further controlled to be more than or equal to 1.2:1 (even if the carbonate ions are excessive, unreacted carbonate is still dissolved in the filtrate, so that the subsequent treatment of the desulfurization lead paste is not influenced; of course, the molar ratio of carbonate ions to sulfate ions can be controlled to be 1.2:1-1.4:1 particularly in consideration of reagent cost and avoiding waste caused by a large amount of unreacted carbonate); stirring and reacting for at least 1h, then separating solid from liquid, wherein the solid is desulfurized lead plaster, and the main component of the filtrate is ammonium sulfate solution which can be recycled as a byproduct.
The obtained desulphurized lead paste is leached by HCl-NaCl mixed solution at 70-90 ℃, the possible reactions are shown in formulas (2) to (6), wherein the reaction of lead dioxide which is most difficult to treat in the desulphurized lead paste and hydrochloric acid (formula (3)) is also thermodynamically feasible (delta G is shown in the following figure 3)<0, indicating that the reaction can proceed forward and that Δg decreases with increasing temperature, the reaction proceeds spontaneously more readily), synchronous reductive chlorination can be achieved. By performing a simulation calculation of the presence of lead chloride in a sodium chloride solution at different pH values, as shown in FIG. 4 hereinafter, when the pH is greater than 6.5, the lead component is formed as lead hydroxide (Pb (OH) 2 ) In the form of (2); when the pH is more than 4.5 and less than 6.5, the lead component exists in the form of basic lead chloride (Pb (OH) Cl); and when the pH is less than 4.5, the lead component is mainly PbCl + And a small amount of lead chloride in dissolved form (lead chloride has dissolved at a temperature of 70-90 ℃). The present invention allows the lead component to be transferred to the leachate by adjusting the pH of the leachable agent to no more than 2.0 (e.g., 1.0-2.0) using a small amount of hydrochloric acid solution.
PbCO 3 +2HCl＝PbCl 2 +H 2 O+CO 2 ↑ (2)
PbO 2 +4HCl＝PbCl 2 +2H 2 O+Cl 2 ↑ (3)
PbO+2HCl＝PbCl 2 +2H 2 O (4)
Pb+2HCl＝ PbCl 2 +H 2 ↑ (5)
Liquid-solid separation is carried out after filtration, and the solid is leaching residues containing Fe, ba and other metal element impurities; the solution is lead chloride in a dissolved state and NaPbCl 3 And Na (Na) 2 PbCl 4 A complex.
Analysis of the behavior of the main impurities Fe and Ba in the leaching process, as known from the results of simulating the distribution morphology of iron elements in sodium chloride solutions of different pH values (as shown in FIG. 5 below), most of the iron elements are Fe 3 O 4 In the form of residual in the leaching residue, a small part of the iron is leached, even if the product PbCl is mixed in during subsequent cooling crystallization 2 In the crystals, the influence on the purity of the product is small, and the recycling of the filtrate is not influenced. While the impurity barium in the desulfurization lead plaster is mostly BaSO 4 Also a small part of BaCO 3 As shown in fig. 6, the barium element is hardly leached, and remains in the leaching residue. Thus, the main component of the obtained solid leaching residue is BaFeO 3 And Fe (Fe) 3 O 4 The content of Fe, ba and other metal impurities in the leaching solution is greatly reduced.
Thus, the leaching solution is subjected to simple recrystallization to obtain the lead chloride crystal with high purity, and the steps of obtaining a solid crude product and then purifying are not needed.
(2) The invention can particularly use a conventional cooling recrystallization method to lead chloride in leaching filtrate to be separated out again in a crystal form at a cooling temperature (for example, -20 ℃ to-4 ℃), and then the target lead chloride crystal product can be obtained through solid-liquid separation. And for the filtrate obtained by solid-liquid separation, the filtrate is a mixed solvent of HCl-NaCl and dissolved lead chloride which is not completely separated out, the mixed solvent can be recycled for hot leaching recrystallization of the desulfurization lead paste, the solvent consumption is almost avoided, and the lead chloride yield can be improved in the next cycle.
(3) With the method of the invention, the concentration of chloride ions in the leaching agent may preferably be at least 4.32mol/L prior to the leaching reaction; in view of the cost of the reagent and avoiding waste caused by a large amount of unreacted Cl ions, the concentration of the chloride ions in the HCl-NaCl mixed solution may be controlled to be 4.32mol/L to 5.19mol/L (of course, even if unreacted Cl ions are present, waste can be avoided if the leaching agent is recycled). In actual operation, the invention can drop 37-38% hydrochloric acid into 250g/L-300g/L sodium chloride solution to make the pH value of the system be 1.0-2.0, thereby obtaining HCl-NaCl mixed solution as leaching agent; unlike the prior art in which saturated sodium chloride solution is directly used to leach by adding excessive hydrochloric acid, the method reduces the concentration of the sodium chloride solution, can integrate lead conversion rate and reagent cost, and realizes the optimal effect.
(4) The existing wet process is to leach the waste lead plaster directly and then cool and crystallize to obtain lead chloride. Calcium chloride is additionally added into the crystallization filtrate to treat sulfate radical in the filtrate, and the filtrate after sulfate radical removal treatment can be recycled. This has the problem of calcium chloride addition, if less, not complete sulfate ions; if the calcium ions are added more, the calcium ions in the filtrate are accumulated, and the leaching effect of subsequent circulation is affected. The process is complicated, and the operation difficulty and the uncertainty of the operation effect in actual mass production can be increased. The invention can achieve at least two effects by carrying out desulfurization treatment on the waste lead plaster without directly leaching the waste lead plaster: (1) the addition amount of hydrochloric acid is reduced. Lead sulfate is difficult to be chloridized and leached, the amount of hydrochloric acid is large, the leaching time is long, the lead sulfate is converted into lead carbonate which is easier to chloridize in the desulfurization process, the dosage of an acidic reagent can be greatly reduced, and the cost is effectively reduced; (2) Sulfate radical is treated in advance by desulfurization, the crystallization filtrate is not required to be treated again, the method can be directly used for the next circulation, and the circulation leaching effect is ensured to be unchanged.
According to the method, the lead sulfate is converted into the lead carbonate by adding desulfurization pretreatment in the process of preparing the lead chloride from the existing waste lead paste, and the recoverable sulfate byproducts are obtained, so that the problem that other impurities are introduced into the whole process due to the fact that the circulating filtrate is treated by adding reagents is avoided, and the acid addition amount of the whole process is reduced. The whole process does not use high-temperature, high-pressure, high-energy consumption and other process conditions, does not have the discharge of lead-containing solution and solid waste, and controls the economic consumption and the environmental impact to the minimum level. The total lead yield of the invention can reach 97%, the short-process wet preparation of lead chloride crystal with purity as high as 99.99% can be realized, and the metal impurities such as Fe, ba and the like are not more than 10ppm.
(4) In the whole process, only three reagents are discharged, wherein sulfate solution generated in the desulfurization process can be recovered as a byproduct, and Fe, ba and Cu impurities in waste lead paste are mainly contained in waste residues generated in the HCl-NaCl mixed solvent leaching and recrystallization process, and filtrate is recycled as a leaching solvent. The yield of the chlorine gas waste gas generated in the leaching reaction is very low, so that PbO in the waste lead plaster is used 2 For example, the content of (3) is 17.93wt%, and the chlorine yield per kilogram of waste lead paste is only 0.74mol. The process has less pollutant exhausted and less environmental pollution.
(5) The invention only inputs three chemical reagents of carbonate solution, sodium chloride solution and hydrochloric acid, wherein, carbonate and sodium chloride are respectively used as desulfurizing agent and chlorine source in the desulfurizing and chloridizing process; the addition amount of the hydrochloric acid is only 3.8mL/L-5.6mL/L; the lead in the filtrate is lead chloride and PbCl in a dissolved state after the chlorine salt solution is recrystallized and filtered 3 - And PbCl 4 2- The method can be directly used for hot dipping of the next batch of desulfurized lead paste, so that the purity of the next batch of products is not affected, and the yield of the next batch of products is improved.
(6) The method has mild reaction conditions and high reaction efficiency. The reaction time of the desulfurization reaction can be as low as 1h, the reaction time of the leaching reaction can be as low as 2h, the time consumption is short, and the production efficiency is greatly increased. The reaction process does not use high-temperature, high-pressure, high-speed stirring and other reaction conditions, the highest reaction temperature can not exceed 90 ℃, and the process is simple and controllable.
(7) The invention can directly obtain the high-purity lead chloride crystal with Fe, ba and other metal impurities lower than 10ppm, and the invention can control the crystal size by controlling the recrystallization process conditions (taking cooling recrystallization as an example, the crystal size of the cooling crystallization is mainly influenced by the cooling speed and the crystallization temperature, the crystal size obtained under the rapid cooling condition is small, the crystal size obtained under the slow cooling condition is large, the crystal size obtained under the higher crystallization temperature is large, and the crystal size obtained under the lower crystallization temperature is small) similar to the recrystallization process control known in the prior art, thereby being beneficial to the subsequent use. The lead chloride yield of the process can be in particular over 90% (e.g. up to 95%) and 5% -10% of the lead-containing component which is not crystallised remains in the crystallisation filtrate and can be passed to the next reaction round.
Drawings
Fig. 1 is a process flow diagram of the wet short process preparation of lead chloride crystals from waste lead paste in the invention.
Figure 2 is an XRD pattern of the desulphurised lead plaster and waste lead plaster raw materials obtained in the process of example 1.
Fig. 3 shows the thermodynamic parameters of the reaction during the reaction of HCl with lead dioxide.
FIG. 4 shows the distribution pattern of the lead-containing component under various pH conditions (the concentration of the lead chloride substance in the solution was 0.01mol/L, the concentration of the sodium chloride substance in the solution was 0.1mol/L, and the reaction temperature was set at 25 ℃).
FIG. 5 shows the distribution of iron impurity under different pH conditions (the concentration of iron ion species in the solution is 0.01mol/L, the concentration of sodium chloride species is 0.1mol/L, and the reaction temperature is set at 25 ℃).
FIG. 6 is an E-pH phase diagram of barium as an impurity (barium ion concentration of 3mol/kg, carbonate ion concentration of 1mol/kg, sulfate ion concentration of 2mol/kg, chloride ion concentration of 1mol/kg in the solution, and reaction temperature of 25 ℃ C.).
Fig. 7 is an XRD pattern of leached impurities obtained during the process of example 1.
Fig. 8 is an XRD pattern of the high purity lead chloride crystals obtained during the procedure of example 1.
Fig. 9 is an SEM image of the high purity lead chloride crystals obtained during the procedure of example 1.
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.
The following are specific examples, each of which satisfies the process flow diagram shown in fig. 1.
In addition, the waste lead paste adopted in each embodiment is from the same batch, and is obtained by crushing and splitting the waste lead acid storage battery by a method known in the prior art. The actual content of lead element in the waste lead plaster is 72.79wt% measured by a chemical titration method, the content of lead sulfate in the waste lead plaster is 72.45wt%, the content of lead dioxide is 17.93wt%, and the detection result of the impurity content of the waste lead plaster is as follows:
Fe：125.3ppm；Ba：111.2ppm；Cu：9.19ppm；Zn：4.90ppm；Al：1.74ppm。
example 1
(1) 5g of waste lead plaster is taken and placed in 50mL of ammonium carbonate solution with the concentration of 30g/L, and the solid-liquid ratio is 100g/L. Stirring and reacting for 1h at 35 ℃, filtering and separating, and drying the solid in an oven at 60 ℃ for 3h to obtain the desulfurized lead plaster with the mass of 4.42g. The filtrate obtained by filtering in the step is sulfate filtrate.
(2) A small amount of hydrochloric acid with the volume fraction of 37% -38% is dropwise added into 111mL of sodium chloride solution with the concentration of 250g/L to prepare NaCl-HCl solution until the pH value of the solution is not more than 2.0, the volume of the dropwise added hydrochloric acid in the embodiment is 600 mu L, and the final pH value of the solution is 1.08. The desulfurization lead plaster obtained in the previous step is placed in 111mL of NaCl-HCl solution, and the solid-liquid ratio is 40g/L. Stirring and leaching for 2-3 h at the water bath heating temperature of 80 ℃, and carrying out solid-liquid separation by hot suction filtration to obtain 113mL of leaching solution. The solid residue obtained by the solid-liquid separation in the step is the solid leaching residue containing Fe, ba and other metal element impurities (the Fe, ba and other metal impurities are mainly remained in the residue in a solid phase form); the filtrate is the leaching solution mainly containing the dissolved lead chloride.
(3) The leaching solution is cooled and recrystallized for 4 hours at the temperature of minus 4 ℃, the solid and the liquid are separated by suction filtration, the obtained solid is dried in an oven at the temperature of 60 ℃ for 2 hours to obtain lead chloride crystals, the quality of the product is 4.67g, the purity of lead chloride in the product is detected, the purity reaches 99.99%, and the total lead yield is calculated to be 95.58%.
The total lead yield is calculated by testing the actual content of lead in the waste lead paste by using a chemical titration method, and then calculating the actual lead chloride yield, purity and mass percent of lead element in the lead chloride, wherein the formula is as follows (the following examples are similar):
wherein: m is m Lead chloride The quality (unit: g) of lead chloride is finally obtained for the experiment; w (w) 1 The lead content (unit:%) of lead chloride is finally obtained for the experiment; m is m Waste lead plaster The quality (unit: g) of the waste lead plaster used as the raw material for the experiment; w (w) 1 The lead content (unit:%) of the waste lead plaster is used as the raw material.
As shown in fig. 2, XRD patterns of the desulfurized lead paste and the waste lead paste raw materials corresponding to the step (1) before and after the treatment can be seen, the lead sulfate is completely converted into lead carbonate after the treatment in the step (1), and a small amount of lead dioxide remains in the desulfurized lead paste.
The solid leaching residue obtained by the solid-liquid separation in the step (2) is shown in FIG. 7, and the main component is BaFeO 3 And Fe (Fe) 3 O 4 。
The solid product of step (3) is lead chloride crystals, as shown in fig. 8 and 9, which are free of other components and exhibit needle-like shape.
Example 2
(1) 5g of waste lead plaster is taken and placed in 50mL of ammonium carbonate solution with the concentration of 32g/L, and the solid-liquid ratio is 100g/L. Stirring and reacting for 1h at 45 ℃, filtering and separating, and drying the solid in an oven at 60 ℃ for 3h to obtain the desulfurized lead plaster with the mass of 4.41g.
(2) A small amount of hydrochloric acid with the volume fraction of 37% -38% is dropwise added into 134mL of sodium chloride solution with the concentration of 300g/L to prepare NaCl-HCl solution until the pH value of the solution is not more than 2.0, wherein the volume of the dropwise added hydrochloric acid is 750 mu L in the embodiment, and the final pH value of the solution is 1.01. The desulfurization lead plaster obtained in the previous step is placed in 134mL of NaCl-HCl solution, and the solid-liquid ratio is 33g/L. Stirring and leaching for 2-3 h at the water bath heating temperature of 80 ℃, and carrying out suction filtration to carry out solid-liquid separation to obtain 137mL of leaching solution.
(3) The leaching solution is cooled and recrystallized for 4 hours at the temperature of minus 4 ℃, the solid and the liquid are separated by suction filtration, the obtained solid is dried in an oven at the temperature of 60 ℃ for 2 hours to obtain lead chloride crystals, the quality of the product is 4.51g, the purity of the lead chloride in the detected product is 99.99%, and the total lead yield is 92.31%.
Example 3
(1) 5g of waste lead plaster is taken and placed in 40mL of ammonium carbonate solution with the concentration of 37g/L, and the solid-liquid ratio is 125g/L. Stirring and reacting for 1h at 55 ℃, filtering and separating, and drying the solid in an oven at 60 ℃ for 3h to obtain the desulfurized lead plaster with the mass of 4.45g.
(2) A small amount of hydrochloric acid with the volume fraction of 37% -38% is dropwise added into 127mL of 260g/L sodium chloride solution to prepare NaCl-HCl solution until the pH of the solution is not more than 2.0, wherein the volume of the dropwise added hydrochloric acid is 490 mu L in the embodiment, and the final pH of the solution is 1.77. The desulfurization lead plaster obtained in the previous step is placed in 127mL of NaCl-HCl solution, and the solid-liquid ratio is 35g/L. Stirring and leaching for 2-3 h at the water bath heating temperature of 80 ℃, and carrying out suction filtration to carry out solid-liquid separation to obtain 129mL of leaching solution.
(3) The leaching solution is cooled and recrystallized for 4 hours at the temperature of minus 4 ℃, the solid and the liquid are separated by suction filtration, the obtained solid is dried in an oven at the temperature of 60 ℃ for 2 hours to obtain lead chloride crystals, the quality of the product is 4.58g, the purity of the lead chloride in the detected product is 99.99%, and the total lead yield is 93.74%.
Example 4
(1) 5g of waste lead plaster is taken and placed in 50mL of ammonium carbonate solution with the concentration of 27g/L, and the solid-liquid ratio is 100g/L. Stirring and reacting for 1h at 55 ℃, filtering and separating, and drying the solid in an oven at 60 ℃ for 3h to obtain the desulfurized lead plaster with the mass of 4.44g.
(2) A small amount of hydrochloric acid with the volume fraction of 37% -38% is dropwise added into 120mL of sodium chloride solution with the concentration of 270g/L to prepare NaCl-HCl solution until the pH value of the solution is not more than 2.0, wherein the volume of the dropwise added hydrochloric acid is 608 mu L in the embodiment, and the final pH value of the solution is 1.26. The desulfurization lead plaster obtained in the previous step is placed in 120mL of NaCl-HCl solution, and the solid-liquid ratio is 37g/L. Stirring and leaching for 2-3 h at the water bath heating temperature of 80 ℃, and carrying out suction filtration to carry out solid-liquid separation to obtain 123mL of leaching solution.
(3) The leaching solution is cooled and recrystallized for 4 hours at the temperature of minus 4 ℃, the solid and the liquid are separated by suction filtration, the obtained solid is dried in an oven at the temperature of 60 ℃ for 2 hours to obtain lead chloride crystals, the quality of the product is 4.65g, the purity of the lead chloride in the detected product is 99.99%, and the total lead yield is 95.17%.
Example 5
(1) 5g of waste lead plaster is taken and placed in 40mL of ammonium carbonate solution with the concentration of 40g/L, and the solid-liquid ratio is 125g/L. Stirring and reacting for 1h at 35 ℃, filtering and separating, and drying the solid in an oven at 60 ℃ for 3h to obtain the desulfurized lead plaster with the mass of 4.39g.
(2) A small amount of hydrochloric acid with the volume fraction of 37% -38% is dropwise added into 146mL of sodium chloride solution with the concentration of 280g/L to prepare NaCl-HCl solution until the pH value of the solution is not more than 2.0, wherein the volume of the dropwise added hydrochloric acid is 792 mu L in the embodiment, and the final pH value of the solution is 1.13. And (3) placing the desulfurization lead plaster obtained in the previous step in 146mL of NaCl-HCl solution, wherein the solid-liquid ratio is 30g/L. Stirring and leaching for 2-3 h at the water bath heating temperature of 80 ℃, and carrying out suction filtration to carry out solid-liquid separation to obtain 147mL of leaching solution.
(3) The leaching solution is cooled and recrystallized for 4 hours at the temperature of minus 20 ℃, the solid and the liquid are separated by suction filtration, the obtained solid is dried in an oven at the temperature of 60 ℃ for 2 hours to obtain lead chloride crystals, the quality of the product is 4.49g, the purity of the lead chloride in the detected product is 99.99%, and the total lead yield is 91.90%.
Example 6
(1) 5g of waste lead plaster is taken and placed in 55mL of ammonium carbonate solution with the concentration of 20g/L, and the solid-liquid ratio is 90g/L. Stirring and reacting for 1h at 45 ℃, filtering and separating, and drying the solid in an oven at 60 ℃ for 3h to obtain the desulfurized lead plaster with the mass of 4.91g (the molar ratio of carbonate ions in carbonate solution to sulfate ions in waste lead plaster is 1:1, the desulfurization is incomplete, and the sulfur content is 0.25%).
(2) A small amount of hydrochloric acid with the volume fraction of 37-38% is dropwise added into 111mL of sodium chloride solution with the concentration of 250g/L to prepare NaCl-HCl solution until the pH of the solution is in the range of 1.0-2.0, the volume of the dropwise added hydrochloric acid is 600 mu L, and the final pH of the solution is 1.08. The desulfurization lead plaster obtained in the previous step is placed in 111mL of NaCl-HCl solution, and the solid-liquid ratio is 40g/L. Stirring and leaching for 2-3 h at the water bath heating temperature of 80 ℃, and carrying out suction filtration to carry out solid-liquid separation to obtain 113mL of leaching solution.
(3) The leaching solution is cooled and recrystallized for 4 hours at the temperature of minus 4 ℃, the solid and the liquid are separated by suction filtration, the obtained solid is dried in an oven at the temperature of 60 ℃ for 2 hours to obtain lead chloride crystals, the quality of the product is 4.33g, the purity of lead chloride in the detected product is 99.74%, and the total lead yield is 88.40%.
Example 7
(1) 5g of waste lead plaster is taken and placed in 40mL of ammonium carbonate solution with the concentration of 37g/L, and the solid-liquid ratio is 125g/L. Stirring and reacting for 1h at 45 ℃, filtering and separating, and drying the solid in an oven at 60 ℃ for 3h to obtain the desulfurized lead plaster with the mass of 4.45g.
(2) A small amount of hydrochloric acid with the volume fraction of 37-38% is dropwise added into 100mL of sodium chloride solution with the concentration of 200g/L (the chloride ion concentration is 3.44 mol/L) to prepare NaCl-HCl solution until the pH value of the solution is in the range of 1.0-2.0, the volume of the dropwise added hydrochloric acid is 400 mu L, and the final pH value of the solution is 1.42. The desulfurization lead plaster obtained in the previous step is placed in 100mL of NaCl-HCl solution, and the solid-liquid ratio is 45g/L. Stirring and leaching for 2-3 h at the water bath heating temperature of 80 ℃, and carrying out suction filtration to carry out solid-liquid separation to obtain 103mL of leaching liquid.
(3) The leaching solution is cooled and recrystallized for 4 hours at the temperature of minus 4 ℃, the solid and the liquid are separated by suction filtration, the obtained solid is dried in an oven at the temperature of 60 ℃ for 2 hours to obtain lead chloride crystals, the quality of the product is 4.01g, the purity of the lead chloride in the detected product is 99.99%, and the total lead yield is 82.08%.
TABLE 1 comparison of parameter conditions with Total lead yield and product purity results for examples 1-7
The lead chloride purity of the products obtained in the above examples is up to 99% or more, especially the products obtained in examples 1 to 5 and example 7, the purity is up to 99.99%, the metal impurities such as Fe and Ba are not more than 10ppm (the purity of 0.01% corresponds to the impurity content of 10 ppm), and the products have the characteristic of short flow, and the high-purity products are directly obtained (the step of re-purifying crude products is not needed).
In addition, as shown in table 1, in order to obtain a higher total lead conversion rate (for example, the total lead conversion rate is more than or equal to 90%), in the desulfurization step of the preparation method of the present invention, the molar ratio of carbonate ions in the carbonate solution to sulfate ions in the waste lead paste is more than or equal to 1.2:1 can be controlled; in the leaching step, the leaching agent may contain, in particular, an excess concentration of chloride ions (for example, the concentration of chloride ions in the leaching agent may be controlled to not less than 4.32 mol/L).
Example 8
The filtrate obtained by solid-liquid separation in the step (3) of the example 1 is used as a leaching liquid, and the method of the invention is circularly carried out, specifically:
(1) 5g of waste lead plaster is taken and placed in 50mL of ammonium carbonate solution with the concentration of 30g/L, and the solid-liquid ratio is 100g/L. Stirring and reacting for 1h at 35 ℃, filtering and separating, and drying the solid in an oven at 60 ℃ for 3h to obtain the desulfurized lead plaster with the mass of 4.42g.
(2) And (3) placing the desulfurization lead plaster obtained in the previous step into 113mL of filtrate (pH=1.38) obtained by solid-liquid separation in the step (3) of the example 1, stirring and leaching for 2-3 h at the water bath heating temperature of 80 ℃, and carrying out suction filtration to obtain 113mL of leaching solution.
(3) The leaching solution is cooled and recrystallized for 4 hours at the temperature of minus 4 ℃, the solid and the liquid are separated by suction filtration, the obtained solid is dried in an oven at the temperature of 60 ℃ for 2 hours to obtain lead chloride crystals, the quality of the product is 4.77g, the purity of the lead chloride in the detected product is 99.99%, and the total lead yield is 97.63%.
Comparative example 1
(1) 5g of waste lead plaster is taken and placed in 40mL of ammonium carbonate solution with the concentration of 37g/L, and the solid-liquid ratio is 125g/L. Stirring and reacting for 1h at 45 ℃, filtering and separating, and drying the solid in an oven at 60 ℃ for 3h to obtain the desulfurized lead plaster with the mass of 4.45g.
(2) A small amount of hydrochloric acid with the volume fraction of 37% -38% is dropwise added into 111mL of sodium chloride solution with the concentration of 250g/L to prepare NaCl-HCl solution, the volume of the dropwise added hydrochloric acid is 50 mu L, and the final pH value of the solution is 3.47. The desulfurization lead plaster obtained in the previous step is placed in 111mL of NaCl-HCl solution, and the solid-liquid ratio is 40g/L. Stirring and leaching for 2-3 h at the water bath heating temperature of 80 ℃, and carrying out suction filtration to carry out solid-liquid separation to obtain 113mL of leaching solution.
(3) The leaching solution is cooled and recrystallized for 4 hours at the temperature of minus 4 ℃, the solid and the liquid are separated by suction filtration, the obtained solid is dried in an oven at the temperature of 60 ℃ for 2 hours to obtain lead chloride crystals, the quality of the product is 3.26g, the purity of the lead chloride in the detected product is 99.99%, and the total lead yield is 66.73%.
The above embodiments are merely examples, and other soluble carbonates (e.g., sodium carbonate, potassium carbonate, ammonium bicarbonate) may be used in addition to ammonium carbonate, all to achieve similar effects. The amount of carbonate solution is determined in particular by the lead sulfate content in the waste lead plaster (for example, the higher the lead sulfate content in the waste lead plaster, the greater the volumetric amount of carbonate solution when the concentration of the carbonate solution is fixed).
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 (8)
1. The method for preparing the lead chloride crystal by the wet short process of the waste lead plaster is characterized by comprising the following steps of:
s1: placing the waste lead plaster into carbonate solution, stirring and reacting for at least 1h, and then carrying out solid-liquid separation, wherein the solid obtained by the solid-liquid separation is the desulfurization lead plaster; wherein the molar ratio of carbonate ions in the carbonate solution to sulfate ions in the waste lead paste is greater than or equal to 1:1;
s2: taking HCl-NaCl mixed solution as a leaching agent, placing the desulfurization lead plaster obtained in the step S1 into the leaching agent, carrying out leaching reaction for at least 2 hours at the temperature of 70-90 ℃, and then carrying out solid-liquid separation to obtain filtrate; wherein the pH of the leachable agent is no more than 2.0;
s3: and (3) recrystallizing the filtrate obtained in the step (S2) and then carrying out solid-liquid separation, wherein the solid obtained by the solid-liquid separation is lead chloride crystals.
2. The method for preparing lead chloride crystals in a short wet process of waste lead plaster according to claim 1, wherein in the step S3, the recrystallization is specifically a recrystallization by cooling;
preferably, the filtrate obtained by the solid-liquid separation can be used as a leaching agent and repeatedly used in the step S2;
more preferably, the temperature adopted by the cooling recrystallization is between-20 ℃ and-4 ℃.
3. The method for preparing lead chloride crystals in a short wet process of waste lead plaster according to claim 1, wherein in the step S2, the concentration of chloride ions in the leaching agent is not less than 4.32mol/L;
preferably, the pH value of the leaching agent is 1.0-2.0; the concentration of chloride ions in the leaching agent is 4.32mol/L-5.19mol/L; the solid-liquid ratio of the desulfurization lead plaster to the leaching agent is 30g/L-40g/L; more preferably, the HCl-NaCl mixed solution is obtained by dropping 37-38% hydrochloric acid into a sodium chloride solution with a concentration of 250g/L to 300g/L to adjust the pH of the system to 1.0-2.0.
4. The method for preparing lead chloride crystals in a short wet process of waste lead plaster according to claim 1, wherein in the step S1, the concentration of carbonate ions in the carbonate solution is 0.36mol/L to 0.29mol/L, and the ratio of the mass of the waste lead plaster to the volume of the carbonate solution is 100g/L to 125g/L.
5. The method for preparing lead chloride crystals in a short wet process of waste lead paste according to claim 1, wherein in the step S1, the molar ratio of carbonate ions in the carbonate solution to sulfate ions in the waste lead paste is 1.2:1 or more; preferably, the molar ratio of carbonate ions in the carbonate solution to sulfate ions in the waste lead paste is 1.2:1-1.4:1;
the stirring reaction is carried out at the temperature of 35-55 ℃; preferably, the temperature condition of 35 ℃ to 55 ℃ is provided by water bath heating.
6. The method for preparing lead chloride crystals in a short wet process of waste lead paste according to claim 1, wherein in the step S1, the stirring speed used for the stirring reaction is 300rpm to 500rpm.
7. The method for preparing lead chloride crystals in a short wet process of waste lead paste according to claim 1, wherein in the step S2, the temperature condition of 70 ℃ to 90 ℃ is provided by heating in a water bath.
8. The method for preparing lead chloride crystals in a short wet process of waste lead plaster according to claim 1, wherein in the step S2, the leaching reaction is performed under stirring conditions, and the stirring speed is 300rpm to 500rpm.
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