CA1190401A - Process for treating sulphated lead compounds for recovering metallic lead and a high-purity sulphate and an installation therefor - Google Patents
Process for treating sulphated lead compounds for recovering metallic lead and a high-purity sulphate and an installation thereforInfo
- Publication number
- CA1190401A CA1190401A CA000401814A CA401814A CA1190401A CA 1190401 A CA1190401 A CA 1190401A CA 000401814 A CA000401814 A CA 000401814A CA 401814 A CA401814 A CA 401814A CA 1190401 A CA1190401 A CA 1190401A
- Authority
- CA
- Canada
- Prior art keywords
- lead
- sodium sulphate
- sulphate
- sulphated
- compounds
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000000034 method Methods 0.000 title claims abstract description 36
- 230000008569 process Effects 0.000 title claims abstract description 33
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 title claims abstract description 15
- 150000002611 lead compounds Chemical class 0.000 title claims abstract description 11
- 238000009434 installation Methods 0.000 title claims abstract description 10
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 title claims abstract description 6
- 229910021653 sulphate ion Inorganic materials 0.000 title claims abstract description 6
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims abstract description 32
- 229910052938 sodium sulfate Inorganic materials 0.000 claims abstract description 16
- 235000011152 sodium sulphate Nutrition 0.000 claims abstract description 16
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims abstract description 15
- 238000002425 crystallisation Methods 0.000 claims abstract description 12
- 230000008025 crystallization Effects 0.000 claims abstract description 12
- 229910000003 Lead carbonate Inorganic materials 0.000 claims abstract description 11
- 230000009467 reduction Effects 0.000 claims abstract description 11
- MFEVGQHCNVXMER-UHFFFAOYSA-L 1,3,2$l^{2}-dioxaplumbetan-4-one Chemical compound [Pb+2].[O-]C([O-])=O MFEVGQHCNVXMER-UHFFFAOYSA-L 0.000 claims abstract description 10
- 238000002386 leaching Methods 0.000 claims abstract description 10
- 150000001875 compounds Chemical class 0.000 claims abstract description 9
- 229910000029 sodium carbonate Inorganic materials 0.000 claims abstract description 7
- 238000004064 recycling Methods 0.000 claims abstract description 6
- 239000000706 filtrate Substances 0.000 claims abstract description 5
- 239000007864 aqueous solution Substances 0.000 claims abstract description 4
- 239000000243 solution Substances 0.000 claims description 8
- 239000013078 crystal Substances 0.000 claims description 7
- 238000001914 filtration Methods 0.000 claims description 5
- 239000000376 reactant Substances 0.000 claims description 4
- 238000001035 drying Methods 0.000 claims description 3
- 239000002244 precipitate Substances 0.000 claims description 2
- 229940112735 lead carbonate Drugs 0.000 claims 3
- 238000006722 reduction reaction Methods 0.000 claims 3
- 206010013786 Dry skin Diseases 0.000 claims 1
- 239000003245 coal Substances 0.000 claims 1
- 238000001816 cooling Methods 0.000 claims 1
- RSIJVJUOQBWMIM-UHFFFAOYSA-L sodium sulfate decahydrate Chemical compound O.O.O.O.O.O.O.O.O.O.[Na+].[Na+].[O-]S([O-])(=O)=O RSIJVJUOQBWMIM-UHFFFAOYSA-L 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 235000017550 sodium carbonate Nutrition 0.000 description 4
- 238000011282 treatment Methods 0.000 description 4
- KEQXNNJHMWSZHK-UHFFFAOYSA-L 1,3,2,4$l^{2}-dioxathiaplumbetane 2,2-dioxide Chemical compound [Pb+2].[O-]S([O-])(=O)=O KEQXNNJHMWSZHK-UHFFFAOYSA-L 0.000 description 3
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 3
- 239000005864 Sulphur Substances 0.000 description 3
- 230000004907 flux Effects 0.000 description 3
- 239000003517 fume Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000000746 purification Methods 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- 239000002893 slag Substances 0.000 description 3
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 235000011941 Tilia x europaea Nutrition 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical compound N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 2
- 229910052921 ammonium sulfate Inorganic materials 0.000 description 2
- 239000001166 ammonium sulphate Substances 0.000 description 2
- 235000011130 ammonium sulphate Nutrition 0.000 description 2
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000004571 lime Substances 0.000 description 2
- 230000001473 noxious effect Effects 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- -1 soda or lime Chemical class 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 235000002918 Fraxinus excelsior Nutrition 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- CZMRCDWAGMRECN-UGDNZRGBSA-N Sucrose Chemical compound O[C@H]1[C@H](O)[C@@H](CO)O[C@@]1(CO)O[C@@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](CO)O1 CZMRCDWAGMRECN-UGDNZRGBSA-N 0.000 description 1
- 229930006000 Sucrose Natural products 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 239000001099 ammonium carbonate Substances 0.000 description 1
- 235000012501 ammonium carbonate Nutrition 0.000 description 1
- 239000002956 ash Substances 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 239000001175 calcium sulphate Substances 0.000 description 1
- 235000011132 calcium sulphate Nutrition 0.000 description 1
- 238000005119 centrifugation Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 229940035564 duration Drugs 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 239000002320 enamel (paints) Substances 0.000 description 1
- 239000003337 fertilizer Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 231100001261 hazardous Toxicity 0.000 description 1
- 231100000206 health hazard Toxicity 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910000464 lead oxide Inorganic materials 0.000 description 1
- 229910021514 lead(II) hydroxide Inorganic materials 0.000 description 1
- XCAUINMIESBTBL-UHFFFAOYSA-N lead(ii) sulfide Chemical compound [Pb]=S XCAUINMIESBTBL-UHFFFAOYSA-N 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000009853 pyrometallurgy Methods 0.000 description 1
- 238000005201 scrubbing Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000005720 sucrose Substances 0.000 description 1
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
- 238000003911 water pollution Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B13/00—Obtaining lead
- C22B13/04—Obtaining lead by wet processes
- C22B13/045—Recovery from waste materials
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Secondary Cells (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The invention described herein is a process for treat-ing sulphated lead compounds, more particularly those coming from exhausted storage batteries, in order to recover metallic lead and a high-purity sulphate, said process comprising subjecting said sulphated compounds to leaching with sodium carbonate in aqueous solution, collecting on a filter the lead carbonate thus obtained from the sodium sulphate which remains dissolved, sub-jecting the lead carbonate to reduction to metallic lead, separa-ting the sodium sulphate by crystallization from the filtrates and recycling the mother liquors of crystallization to the leach-ing stage. The invention also provides an installation for per-forming the above pr .
The invention described herein is a process for treat-ing sulphated lead compounds, more particularly those coming from exhausted storage batteries, in order to recover metallic lead and a high-purity sulphate, said process comprising subjecting said sulphated compounds to leaching with sodium carbonate in aqueous solution, collecting on a filter the lead carbonate thus obtained from the sodium sulphate which remains dissolved, sub-jecting the lead carbonate to reduction to metallic lead, separa-ting the sodium sulphate by crystallization from the filtrates and recycling the mother liquors of crystallization to the leach-ing stage. The invention also provides an installation for per-forming the above pr .
Description
This invention rela-tes to a process for treating sul-phated lead compounds for recovering metallic lead therefrom and, concurrently therewith, a high-purity sulphate, and an installa-tion for performing said process.
The process of the presen-t inven-tion is par-ticularly suited to the trea-tmen-t of sulphated lead compounds coming from acidic storage batteries with lead electrodes, which are exhaus-ted ("electrode pastes").
Many a process is known for recovering metallic lead from the "exhausted pastes" and from the sludges of the exhausted batteries; for example, pyrometallurgical processes are commonly known, in which the sulphated lead deriva-tives, mostly lead sul-phate and lead sulphide, are thermally reduced to metallic lead.
Serious objections against such processes are, on the one hand, the necessi-ty of using reagents, such as iron and pyri-te ashes, or slag forming compounds, such as soda or lime, at hiyh -tempera-tures, and, on the other hand, -the fac-t that a high percentage of -the sulphur which is contained in the startiny materials is converted into noxious s~llphurous gases which, i discharged 2r~ into the atmosE)here, cause ecological damage. I-t is thus imperative to install purification systems in which the exhausted sulphurous gases are subjected to scrubbing, for example with alkaline solutions, based on lime or ammoniacal solutions.
It is apparent that this is a serious source of expendi-ture due -to the capi-tal and running cos-ts of such purification systems, so that this technology has grea-t limitations.
3r) /
~
I-lydrometallurgical processes such as those disclosed by the U.S. Patents 3,8~33,3~8 and 4,119,219 are alsQ known.
These patents describe processes in which the materials which contain lead sulpha-te are treated with a solution of ammonium carbonate to give lead carbonate and ammonium sulphate, the lat-ter being recovered for use as a fertilizer. Typical draw-backs of such processes are, however, the formation of ammoniacal gases and thus the processing conditions are hazardous and the necessity is felt of having specially designed systems available for concentrating the ammonium sulphate solu-tions and recovering the reactants, so -that such processes are also economically objec-tionable.
The RI 3123 of the Bureau of Mines (U.S. Department of the Interior) describes the use of calcium hydroxide for con-ver-ting lead sulphate into lead hydroxide. Concurrently, in-soluble calcium sulphate is formed so -that it becomes necessary to carry out a reducing rnelting of the mixture thus obtained in the presence of a large amount of a "flux" such as a mixture of sodiurn chloride and potassium ch]oride.
A:LthoucJh the temperature at which such a reductlon is :Iow, the great mass of substances to be melted makes -the pro-cess of doubtful acceptance from an economical standpoint. More-over, additional treatments are required to recover the fluxes.
Britich Patent l,535,025 discloses the dissolu-tion of a "spent paste" which contains lead oxides and sulphates in-to an alkaline electrolyte, in the presence of sucrose so as to form a complex with lead, the solu-tion thus obtained being -then electrolyzed with insoluble anodes to recover metallic lead.
i, I~his process is also bo-th intricate and economic~ally objectionable.
U.S. Patent 4,018,567 describes an apparatus which is ratller intricate and is intended for the separation of -the several component par-ts of acidic lead storage batteries.
In order to form, together with the finer particles of the active mass of -the storaye battery, the thick me~ium which is required for making the lighter component parts, such as the separators and ~he casings, buoyant, while sinking the me-tallic component parts, such as bridge-poles and grids, the British Patent uses a solution o:E sodium carbonate. The Patent mainly discloses an intricate device for hydraulically and mechanically separating -the several component parts involved, but does not give any adequate suggestions as to -the procedure for making the recovery sys-tem for -the several components economically advantageous: this cou]d be done by a system which, in addition to a satisfactory recovery of the me-tal, would concurren-tly provide a complete and advan-tageous recovery of -the sulphated compounds, -that which would also preven-t the ecological damage due to their scatteri.ng i.n the environment.
It can thus be apprecia-ted that the processes as adop--ted heretofore for recovering metallic lead from i-ts sulphated compounds involve problems which are predominantly health-hazard problems and economic disadvantage problems due to the processing conditions.
3~
~.~
/ ' This invention overcomes -the problems encountered with the processes of -the prior art in this field. According to the presen-t invention there is provided a process for -treating sulphated lead compounds, more particularly those coming from spen-t storage batteries, to recover both me-tallic leacl and a high-purity sulphate, which comprises subjecting said sulphated compounds to leaching wi-th sodium carbonate in aqueous solution, collecting on a fil-ter the lead carbonate precipita-te thus ob-tained from the dissolved sodium sulphate, subjecting -the lead carbonate to reduction to metallic lead, separating the sodium sulphate by crystallization from the filtrates and recycling the crystallization mother liquors to the leaching stage.
The present inven-tion further provides an installa-tion for performing the process referred to above, said installation comprising a reactor for carrying out -the leaching of said sul-phated lead compounds with sodium carbona-te, means Eor feeding the reactants to the reactor, means for carrying out -the fi]tra-tion of the liquor exiting the reactor, a kiln for the thermal reduction of ]ead carbonate to give metallic lead, crys-talliza-tion vats for separating the sod:iurn su:Lpahte from -the filtra-tes and rneans for recycling the crystallization mother liquors to said reactor.
The present invention will be further il~ustrated by way of the accompanying drawing, which is a flow diagram of the process according to a preferred embodiment of the invention.
~ _ /
Referring to the diagram, a "spen-t pas-te" of exhausted storage batteries, which mainly contains lead sulphaté, is char-ged at 11 into a reactor 12, ~or example a vat having heating and stirring means, which is also fed at 13 and 14 with an aqueous solution of Na2CO3 of medium strength. The "spent paste" charged at 12 is obtained by separating the paste from the remaining component parts of the s-torage ba-tteries by any appropriate method, for example as disclosed in the U.S. Patent Nos. 3,456,886 and 3,614,003.
In the reactor 12, which is maintained at a tem-6.
perature be-t~Yecn 30C and 40C with stirring for about one hour, the leaching stage is carried out, so -that a double-excl)ange reaction tal<es place hetw~en the reacting salts, the result being the formation of lead carbonate in the iform of an insolubl.e precipitate, and v~ry 1 the formation of sodium su].phate which is oxtrcmcly so-luble in ho-t tvater and which thus remains disso~.ved therei.n. ~nee tne reaction has been eompleted, the mixture thus obtained is -fed to a filtration stage 15, 1~ such as a -filter-press, to separate the precipi.tate from the solution. At -the exit from this stage,ther.e is obtained at 16, a solid which contains the derivati~
ves, main~y lead earbonatc, of the learl ch~rge coming from 11. The solids are dried at 17 and fed at 18 tV a stage Or reduction, in a Iciln to wh;.eh coa]. .Ls -fecl dt 19 in the necessary amount (rouc)h].y 4% of the soli.d<; by we:Lgllt ), ~rom the reduetion k-;.ln, whien is Maintcli.ned at about 900C for one hour, ra-.Y metallic lead is drawn at 20, The fil-tra-te 219 coming -from ttle filtration stage 15, contains the as-produced sodium sulphate and the unreacted sodium carbonate from the leaching stage.
The filtrate is collectcd in crys-ta].li~ati.on vats 22, ~/hercin, by merely allowlncJ the liquor to cvol at room temperature, crystals of decahydrous sodlurn sulphate can gro~,. On completi.on of crystalli~ati.on, the mo-theJ li~uors 23 e~.i.tin(J 22 are recycled to the reactor 12 for the sutJsc~lent step.
The crystals of sodium sulphate coming from the vats 22 are strained by centrifugation at 2~, collec-ted at 25 and subjected at 26 -to drying in a low-tempera-ture air-s-tream to give a high-purity anhydrous sodium sulphate which can be used for enamel coatings or glass mills direc-tly and without requir-ing any fur-ther purification s-teps.
The process allows the conversion of -the s-tar-ting sul-pha-ted lead compounds into two recovered products having a high quality, such as raw metallic lead and pure anhydrous sodium sulphate, without being affected by any of the difficulties dis-cussed above relatively to -the prior ar-t in this field.
The vi.rtually to-tal conversion of the charged lead into its non-sul.phated compounds, mainly PbCO3, allows a kiln reduction to be effected with times which are much shor-ter and at temperatures which are mus-t lower -than those in the hitherto conven-tional processes of reduction of lead sulphate (or sul-phide), and, above all, no fluxes or slag-:Eormers are required.
In the process according to this invention on compari-son wi.th conventional pyrometa].lurgical procedures, the potential output of the reduction k:iln is irnproved by about 15%, the dura-tion of the refractory liners of -the kiln is ex-tended by abou-t 60%, the formation of fumes and slags is reduced by about 65%, the lead losses by scattering in the fumes and slags is reduced by about 50%, and finally, the power consumption is reduced by about 30%.
3~
~9¢~
Above all, -the process according to this lnvention, by providing for the -total conversion of the sulphated lead com-pounds into lead carbonate prior to -the redcution stage, pre-vents, in the latter stage, the emission of sulphurous gases, which, conversely, was invariably experienced in all those pro-cesses in which sulphated lead compounds were reduced. The starting sulphur, not only is no more scattered in the a-tmos-phere in the form of noxious gases, but, conversely, is conver-ted, in its turn, into a high-purity compound, that is sodium sulphate, the commercial value of which can be estimated to be such as to balance the processing costs for the added reac-tants.
An additional, considerable advan-tage afforded by -the process of the invention is that the sodium sulphate exiting the processing run, inasmuch as it crystallizes with 10 mols of water per mol of salt, considerably reduces the amount of water in use, whereby the recycling of -the mo-ther liquors of the pro-cess is faci.litated and the possibility of any water pollu-tion in -the environment of the installa-tion is dras-tically reduced~
The process according to -this invention allows the lead contained in sulpha-ted lead res:idues to be recovered with a mini.rnum loss of metal, a maximum economical effi.ciency and a substantial reduction of any risk of pollu-tion of the environ-ment.
/
The presen-t inven-tion thus affords a clean technology which is adap-ted to -the treatment of all the sulphatea compounds of lead. The process can advantageously be adopted, no-t only to -the treatment of spent pastes and sludges from exhausted lead storage ba-tteries to which it is particularly adap-ted, but also -to the trea-tment of sulphur-containing lead fumes and ores, after an appropriate sulphation of -the materials -to be processed.
.~...
The process of the presen-t inven-tion is par-ticularly suited to the trea-tmen-t of sulphated lead compounds coming from acidic storage batteries with lead electrodes, which are exhaus-ted ("electrode pastes").
Many a process is known for recovering metallic lead from the "exhausted pastes" and from the sludges of the exhausted batteries; for example, pyrometallurgical processes are commonly known, in which the sulphated lead deriva-tives, mostly lead sul-phate and lead sulphide, are thermally reduced to metallic lead.
Serious objections against such processes are, on the one hand, the necessi-ty of using reagents, such as iron and pyri-te ashes, or slag forming compounds, such as soda or lime, at hiyh -tempera-tures, and, on the other hand, -the fac-t that a high percentage of -the sulphur which is contained in the startiny materials is converted into noxious s~llphurous gases which, i discharged 2r~ into the atmosE)here, cause ecological damage. I-t is thus imperative to install purification systems in which the exhausted sulphurous gases are subjected to scrubbing, for example with alkaline solutions, based on lime or ammoniacal solutions.
It is apparent that this is a serious source of expendi-ture due -to the capi-tal and running cos-ts of such purification systems, so that this technology has grea-t limitations.
3r) /
~
I-lydrometallurgical processes such as those disclosed by the U.S. Patents 3,8~33,3~8 and 4,119,219 are alsQ known.
These patents describe processes in which the materials which contain lead sulpha-te are treated with a solution of ammonium carbonate to give lead carbonate and ammonium sulphate, the lat-ter being recovered for use as a fertilizer. Typical draw-backs of such processes are, however, the formation of ammoniacal gases and thus the processing conditions are hazardous and the necessity is felt of having specially designed systems available for concentrating the ammonium sulphate solu-tions and recovering the reactants, so -that such processes are also economically objec-tionable.
The RI 3123 of the Bureau of Mines (U.S. Department of the Interior) describes the use of calcium hydroxide for con-ver-ting lead sulphate into lead hydroxide. Concurrently, in-soluble calcium sulphate is formed so -that it becomes necessary to carry out a reducing rnelting of the mixture thus obtained in the presence of a large amount of a "flux" such as a mixture of sodiurn chloride and potassium ch]oride.
A:LthoucJh the temperature at which such a reductlon is :Iow, the great mass of substances to be melted makes -the pro-cess of doubtful acceptance from an economical standpoint. More-over, additional treatments are required to recover the fluxes.
Britich Patent l,535,025 discloses the dissolu-tion of a "spent paste" which contains lead oxides and sulphates in-to an alkaline electrolyte, in the presence of sucrose so as to form a complex with lead, the solu-tion thus obtained being -then electrolyzed with insoluble anodes to recover metallic lead.
i, I~his process is also bo-th intricate and economic~ally objectionable.
U.S. Patent 4,018,567 describes an apparatus which is ratller intricate and is intended for the separation of -the several component par-ts of acidic lead storage batteries.
In order to form, together with the finer particles of the active mass of -the storaye battery, the thick me~ium which is required for making the lighter component parts, such as the separators and ~he casings, buoyant, while sinking the me-tallic component parts, such as bridge-poles and grids, the British Patent uses a solution o:E sodium carbonate. The Patent mainly discloses an intricate device for hydraulically and mechanically separating -the several component parts involved, but does not give any adequate suggestions as to -the procedure for making the recovery sys-tem for -the several components economically advantageous: this cou]d be done by a system which, in addition to a satisfactory recovery of the me-tal, would concurren-tly provide a complete and advan-tageous recovery of -the sulphated compounds, -that which would also preven-t the ecological damage due to their scatteri.ng i.n the environment.
It can thus be apprecia-ted that the processes as adop--ted heretofore for recovering metallic lead from i-ts sulphated compounds involve problems which are predominantly health-hazard problems and economic disadvantage problems due to the processing conditions.
3~
~.~
/ ' This invention overcomes -the problems encountered with the processes of -the prior art in this field. According to the presen-t invention there is provided a process for -treating sulphated lead compounds, more particularly those coming from spen-t storage batteries, to recover both me-tallic leacl and a high-purity sulphate, which comprises subjecting said sulphated compounds to leaching wi-th sodium carbonate in aqueous solution, collecting on a fil-ter the lead carbonate precipita-te thus ob-tained from the dissolved sodium sulphate, subjecting -the lead carbonate to reduction to metallic lead, separating the sodium sulphate by crystallization from the filtrates and recycling the crystallization mother liquors to the leaching stage.
The present inven-tion further provides an installa-tion for performing the process referred to above, said installation comprising a reactor for carrying out -the leaching of said sul-phated lead compounds with sodium carbona-te, means Eor feeding the reactants to the reactor, means for carrying out -the fi]tra-tion of the liquor exiting the reactor, a kiln for the thermal reduction of ]ead carbonate to give metallic lead, crys-talliza-tion vats for separating the sod:iurn su:Lpahte from -the filtra-tes and rneans for recycling the crystallization mother liquors to said reactor.
The present invention will be further il~ustrated by way of the accompanying drawing, which is a flow diagram of the process according to a preferred embodiment of the invention.
~ _ /
Referring to the diagram, a "spen-t pas-te" of exhausted storage batteries, which mainly contains lead sulphaté, is char-ged at 11 into a reactor 12, ~or example a vat having heating and stirring means, which is also fed at 13 and 14 with an aqueous solution of Na2CO3 of medium strength. The "spent paste" charged at 12 is obtained by separating the paste from the remaining component parts of the s-torage ba-tteries by any appropriate method, for example as disclosed in the U.S. Patent Nos. 3,456,886 and 3,614,003.
In the reactor 12, which is maintained at a tem-6.
perature be-t~Yecn 30C and 40C with stirring for about one hour, the leaching stage is carried out, so -that a double-excl)ange reaction tal<es place hetw~en the reacting salts, the result being the formation of lead carbonate in the iform of an insolubl.e precipitate, and v~ry 1 the formation of sodium su].phate which is oxtrcmcly so-luble in ho-t tvater and which thus remains disso~.ved therei.n. ~nee tne reaction has been eompleted, the mixture thus obtained is -fed to a filtration stage 15, 1~ such as a -filter-press, to separate the precipi.tate from the solution. At -the exit from this stage,ther.e is obtained at 16, a solid which contains the derivati~
ves, main~y lead earbonatc, of the learl ch~rge coming from 11. The solids are dried at 17 and fed at 18 tV a stage Or reduction, in a Iciln to wh;.eh coa]. .Ls -fecl dt 19 in the necessary amount (rouc)h].y 4% of the soli.d<; by we:Lgllt ), ~rom the reduetion k-;.ln, whien is Maintcli.ned at about 900C for one hour, ra-.Y metallic lead is drawn at 20, The fil-tra-te 219 coming -from ttle filtration stage 15, contains the as-produced sodium sulphate and the unreacted sodium carbonate from the leaching stage.
The filtrate is collectcd in crys-ta].li~ati.on vats 22, ~/hercin, by merely allowlncJ the liquor to cvol at room temperature, crystals of decahydrous sodlurn sulphate can gro~,. On completi.on of crystalli~ati.on, the mo-theJ li~uors 23 e~.i.tin(J 22 are recycled to the reactor 12 for the sutJsc~lent step.
The crystals of sodium sulphate coming from the vats 22 are strained by centrifugation at 2~, collec-ted at 25 and subjected at 26 -to drying in a low-tempera-ture air-s-tream to give a high-purity anhydrous sodium sulphate which can be used for enamel coatings or glass mills direc-tly and without requir-ing any fur-ther purification s-teps.
The process allows the conversion of -the s-tar-ting sul-pha-ted lead compounds into two recovered products having a high quality, such as raw metallic lead and pure anhydrous sodium sulphate, without being affected by any of the difficulties dis-cussed above relatively to -the prior ar-t in this field.
The vi.rtually to-tal conversion of the charged lead into its non-sul.phated compounds, mainly PbCO3, allows a kiln reduction to be effected with times which are much shor-ter and at temperatures which are mus-t lower -than those in the hitherto conven-tional processes of reduction of lead sulphate (or sul-phide), and, above all, no fluxes or slag-:Eormers are required.
In the process according to this invention on compari-son wi.th conventional pyrometa].lurgical procedures, the potential output of the reduction k:iln is irnproved by about 15%, the dura-tion of the refractory liners of -the kiln is ex-tended by abou-t 60%, the formation of fumes and slags is reduced by about 65%, the lead losses by scattering in the fumes and slags is reduced by about 50%, and finally, the power consumption is reduced by about 30%.
3~
~9¢~
Above all, -the process according to this lnvention, by providing for the -total conversion of the sulphated lead com-pounds into lead carbonate prior to -the redcution stage, pre-vents, in the latter stage, the emission of sulphurous gases, which, conversely, was invariably experienced in all those pro-cesses in which sulphated lead compounds were reduced. The starting sulphur, not only is no more scattered in the a-tmos-phere in the form of noxious gases, but, conversely, is conver-ted, in its turn, into a high-purity compound, that is sodium sulphate, the commercial value of which can be estimated to be such as to balance the processing costs for the added reac-tants.
An additional, considerable advan-tage afforded by -the process of the invention is that the sodium sulphate exiting the processing run, inasmuch as it crystallizes with 10 mols of water per mol of salt, considerably reduces the amount of water in use, whereby the recycling of -the mo-ther liquors of the pro-cess is faci.litated and the possibility of any water pollu-tion in -the environment of the installa-tion is dras-tically reduced~
The process according to -this invention allows the lead contained in sulpha-ted lead res:idues to be recovered with a mini.rnum loss of metal, a maximum economical effi.ciency and a substantial reduction of any risk of pollu-tion of the environ-ment.
/
The presen-t inven-tion thus affords a clean technology which is adap-ted to -the treatment of all the sulphatea compounds of lead. The process can advantageously be adopted, no-t only to -the treatment of spent pastes and sludges from exhausted lead storage ba-tteries to which it is particularly adap-ted, but also -to the trea-tment of sulphur-containing lead fumes and ores, after an appropriate sulphation of -the materials -to be processed.
.~...
Claims (8)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for treating sulphated lead compounds for recovering metallic lead and a high-purity sulphate, which comprises subjecting said sulphated compounds to leaching with an aqueous solution of sodium carbonate, collecting on a filter the lead carbonate precipitate thus obtained to separate it from the dissolved sodium sulphate, subjecting the lead car-bonate to reduction to metallic lead, separating the sodium sulphate by crystallization from the filtrates, and recycling the crystallization mother liquors to the leaching stage.
2. A process according to claim 1, in which said reduc-tion stage is carried out thermally, in the presence of coal at a temperature below 1000°C.
3. A process according to claim 1, in which said cry-stallization stage is carried out by cooling said solution to give crystals of sodium sulphate decahydrate.
4. A process according to claim 3, in which said crystals separated from the mother liquors are subjected to dry-ing to yield anhydrous sodium sulphate to be sent to storage.
5. An installation for carrying out the process claimed in claim 1, comprising a reactor for carrying out leaching of said sulphated lead compounds with sodium carbonate, means for feeding the reactants to said reactor, means for carrying out filtration of the solution exiting the reactor, a kiln for the thermal reduction of lead carbonate to give metallic lead, cry-stallization vats for separating sodium sulphate in crystals from the mother liquors of said filtration and means for recycling the mother liquors separated from said crystals to said reactor.
6. An installation according to claim 5, in which said filtration means is a filter-press.
7. An installation according to claim 5, which comprises a centrifuge for separating the sodium sulphate from the cry-stallization mother liquors.
8. An installation according to claim 5, which com-prises devices for drying the crystals or hydrous sodium sulphate as obtained in said crystallization stage.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IT21447A/81 | 1981-04-29 | ||
| IT2144781A IT1136589B (en) | 1981-04-29 | 1981-04-29 | PROCEDURE FOR THE TREATMENT OF LEAD SULPHATE COMPOUNDS TO RECOVER METALLIC LEAD AND A HIGH-PURITY SULPHATE, AND PLANT FOR ITS REALIZATION |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1190401A true CA1190401A (en) | 1985-07-16 |
Family
ID=11181911
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000401814A Expired CA1190401A (en) | 1981-04-29 | 1982-04-28 | Process for treating sulphated lead compounds for recovering metallic lead and a high-purity sulphate and an installation therefor |
Country Status (8)
| Country | Link |
|---|---|
| BR (1) | BR8202453A (en) |
| CA (1) | CA1190401A (en) |
| DE (1) | DE3215592A1 (en) |
| ES (1) | ES511763A0 (en) |
| FR (1) | FR2504940A1 (en) |
| GB (1) | GB2097774B (en) |
| IT (1) | IT1136589B (en) |
| YU (1) | YU88682A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT1191650B (en) * | 1986-01-09 | 1988-03-23 | Tecneco Spa | HYDROMETALLURGIC PROCESS FOR A TOTAL RECOVERY OF THE COMPONENTS OF EXHAUSTED LEAD ACID BATTERIES |
| DE3612491A1 (en) * | 1986-04-14 | 1987-10-15 | Preussag Ag Metall | Process for recovering lead from oxidic or oxidic/sulphatic secondary precursor materials |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1587623A (en) * | 1925-03-02 | 1926-06-08 | Max E Zuckerman | Process of reclaiming the constituents of lead battery plates |
| US2152242A (en) * | 1935-08-10 | 1939-03-28 | Leo P Curtin | Recovery of lead values |
| US3892563A (en) * | 1973-05-14 | 1975-07-01 | Point Albert E | Method and apparatus for separating the constituents of lead-acid storage batteries |
| US4269810A (en) * | 1978-10-10 | 1981-05-26 | Nl Industries, Inc. | Method for desulfation of battery mud |
| FI63781B (en) * | 1980-03-19 | 1983-04-29 | Outokumpu Oy | FOERFARANDE FOER AOTERVINNING AV VAERDEMETALLER UR FINMALEN PYIT |
-
1981
- 1981-04-29 IT IT2144781A patent/IT1136589B/en active
-
1982
- 1982-04-22 GB GB8211634A patent/GB2097774B/en not_active Expired
- 1982-04-23 YU YU88682A patent/YU88682A/en unknown
- 1982-04-27 DE DE19823215592 patent/DE3215592A1/en not_active Withdrawn
- 1982-04-28 CA CA000401814A patent/CA1190401A/en not_active Expired
- 1982-04-28 BR BR8202453A patent/BR8202453A/en unknown
- 1982-04-28 ES ES511763A patent/ES511763A0/en active Granted
- 1982-04-29 FR FR8207423A patent/FR2504940A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| IT8121447A0 (en) | 1981-04-29 |
| DE3215592A1 (en) | 1982-11-18 |
| GB2097774A (en) | 1982-11-10 |
| IT1136589B (en) | 1986-09-03 |
| BR8202453A (en) | 1983-04-12 |
| ES8302111A1 (en) | 1983-02-01 |
| YU88682A (en) | 1985-03-20 |
| ES511763A0 (en) | 1983-02-01 |
| GB2097774B (en) | 1985-03-06 |
| FR2504940A1 (en) | 1982-11-05 |
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