Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
  • C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
  • C25C1/18—Electrolytic production, recovery or refining of metals by electrolysis of solutions of lead
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/54—Reclaiming serviceable parts of waste accumulators
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/84—Recycling of batteries or fuel cells

Definitions

• the present invention is directed to the recovery of metallic lead from battery paste.
• various methods have been proposed.
• it is of importance to recover these metals, and more in particular lead therefrom.
• Spent batteries can be comminuted, followed by separation of the lead containing components from the remainder of the battery, mainly plastics.
• the lead containing components are obtained in the form of a pasty product, battery paste.
• This battery paste consists mainly of salts and oxides of lead in particle form, together with an amount of water.
• the predominant components in the battery paste are lead(II)sulphate, lead(II)oxide and lead(IV)oxide.
• lead(II)sulphate lead(II)oxide
• lead(IV)oxide lead(IV)oxide.
• the invention aims at providing an alternative process for the recovery of metallic lead from battery paste, which process does not possess the disadvantages of the known pyro-metallurgical process.
• the invention is based on the insight, that it is possible to process battery paste in an electrolysis unit having at least a high surface area cathode means under production of metallic lead in a pure form, without the problem inherent to the known process.
• the invention is directed to a process for the recovery of metallic lead from battery paste, comprising introducing the battery paste into at least one electrolysis unit, said unit comprising, anode and cathode means as electrode means arranged therein, at least said cathode means being a high surface area electrode means, and a liquid electrolyte containing an effective amount of complexing agent, and electrochemically depositing metallic lead upon said cathode means.
• the invention further provides a process in which the electrolysis unit consists of an anode and a cathode compartment which are separated from each other by means of a diaphragm or a selective membrane. High surface areas for the electrode means from 40 to 5000 m are preferred.
• further embodiments of the invention comprise stretch-metal electrodes (see article by D.P. Ziegler et al. , "A preliminary investigation of some anodes for use in fluidized bed electrodeposition of metals", “Journal of Applied Electrochemistry", V. 11 (1981), p. 625-637) and electrically conducting particles.
• electrically conducting particles comprise a wide variety, for example from copper and steel particles to even silicium carbide particles.
• the battery paste is introduced into said cathode compartment being separated from the anode compartment by means of an anion selective membrane.
• the high surface cathode means comprises electrically conducting particles, in particular lead particles, which form a fluidized bed.
• a fluidized bed electrolysis cell comprises an anode compartment and a cathode compartment which are separated from each other by a diaphragm or membrane (see article by A. Herrera, "Halides and sulphate ion diffusion in nafion membranes", Journal of Electrochemical Science and Technology, V. 134, 1987, No. 10, p. 2446-2450).
• the cell is filled with liquid electrolyte, such as an aqueous solution of sulphuric acid and sodium sulphate.
• the cathode compartment contains particles of a conductive metal, usually the metal to be obtained in the process. These particles are kept in fluidized state by an upflow of liquid.
• the electrical charge which makes the particles function as a cathode results from particle contact with current feeders as well as from contact with other particles.
• the lead particles are continuously or intermittently removed from the cathode compartment as product and are replenished with finer particles.
• the fluidization of the particles in the bed is obtained by a recirculation of the catholyte, containing dispersed therein the battery paste.
• fresh battery paste is continuously or intermittently added to the recirculating catholyte.
• the battery paste consists of a mixture of lead salt and oxides in divalent and tetravalent form.
• a suitable amount of solid lead(II)sulphate in the slurry lies between 0.5 and 20 m.%.
• This treatment can be done in any convenient manner, but it is preferred to take up the S0_ in an alkaline solution, thereby forming a solution of Na personallyS0_. This is preferably done in a scrubber, wherein the S0 toast containing gas is scrubbed with the alkaline solution.
• the solution of sodium sulphite obtained thereby is used to treat the battery paste.
• the thus treated battery paste wherein the major part of the lead will be in divalent form, can then be separated from the liquid and can be introduced into the recirculating catholyte.
• this process has important advantages. Not only is it very easy to treat the battery paste in this way, but it also takes care of a waste gas stream. In case the amount of S0 condiment that is produced, fluctuates with time it may be possible to have a buffer vessel for the sodium sulphite solution.
• Both the above said catholyte and alkaline solution can contain an effective amount of complexing agent.
• the amount thereof varies depending on the type of complexing agent.
• the amount should be such that sufficient divalent lead is available in dissolved form for electrolysis.
• Suitable amounts of dissolved lead are at least 0.3 g/1, preferably at least 1.0 g/1.
• the upper limit is not very important, but can for example be 15 g/1.
• a suitable range for the amount of complexing agent is from 5 mmol/1 to 0.5 mol/1.
• complexing agent various agents can be used. An important factor is the pH at which it functions as complexing agent, in relation to the pH at which the membrane can function. Suitable agents are i.a. nitrilotriacetic acid, EDTA, acetic acid, oxalic acid, malonic acid, and mixtures of two or more of these complexing agents and salts thereof. A preferred agent is nitrilotriacetic acid (NTA) , as this can be used with rather mild pH values, within a broad range.
• NTA nitrilotriacetic acid
• the process can be carried out in one electrochemical cell, but it is also possible to use a combination of cells, each using a different size of lead particles.
• the specific choice depends mainly on the economy of the process.
• the process conditions like temperature, pH, flow of electrolyte, particle size of the electrically conducting particles, current density, type of membrane, type of anode/current feeder, etc. can be determined by one skilled in the art on the basis of the known criteria. For the applications as mentioned above temperatures between 20 and 90 "C, pH-values between 1 and 11, current densities between 200 and
• the electrolysis cell 1 is provided with an anode
• the anode and cathode compartments (5 and 6) are separated from each other by an anion-selective membrane 4.
• the liquid in the anode compartment 5 is recirculated through line 7.
• Through line 8 diluted sulphuric acid is removed, whereas through line 9 fresh water is added to the system to compensate for the water removed from the anode compartment 5.
• the cathode compartment 6 contains lead particles that are kept in fluidized state by the recirculation of slurry through line 10. A part of the lead particles is removed as product through line 11. New particles can be added through line 12.
• fresh battery paste can be added through line 13, whereas fresh complexing agent can be added through line 14.
• a system for pretreatment of battery paste is described.
• This system consists of an SO-, scrubber 21 to which a recirculated alkaline NTA containing solution is fed through line 22.
• S0 «-containing gas is introduced in the scrubber 21 through line 23 and the scrubbed gas is removed from the scrubber 21 through line 24.
• the sulphite-containing liquid is removed from the scrubber through line 25 and introduced in vessel 26 to which also battery paste is fed through line 27.
• the battery paste is treated whereby the major part of the lead is converted to divalent state.
• the slurry of treated battery paste is removed from the vessel through line 28, followed by a rough solid liquid separation in separator 30.
• the slurry is fed at a rate of 200 ml/h and the pH of the catholyte is controlled by the addition of 10 M NaOH.
• the electrolysis unit consisted of one cathode compartment between two anode compartments. A lead/silver anode was used, whereas the current feeder in the cathode compartment consisted of a copper feeder plate.
• the catholyte composition was kept at 0.5 mol/1 sodium sulphate and 0.005 mol/1 NTA.
• the solids content of the solution varied between about 0.5 and 1.5 m/m%.
• the pH of the catholyte was kept at 4.0 at a temperature of 50 ⁇ C.
• As anolyte a 2 m/m% sulphuric acid solution was used.
• the cell voltage was 3.2 V at a current density of 750 A/m .
• the space time yield was 16 kg/m .h.
• the high surface area of the fluidized lead particles changed from about 3500 to 2000 m .
• Results of the experiments are expressed in Pb-recovery-values, being percentages of the amount of lead introduced into the cell compared to the amount of lead recovered.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• General Chemical & Material Sciences (AREA)
• Electrolytic Production Of Metals (AREA)
• Secondary Cells (AREA)

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• 1991
  • 1991-02-13 GB GB9102994A patent/GB9102994D0/en active Pending
• 1992
  • 1992-02-10 EP EP92904104A patent/EP0573452A1/de not_active Ceased
  • 1992-02-10 WO PCT/EP1992/000306 patent/WO1992014866A1/en not_active Ceased
  • 1992-02-10 CA CA 2104398 patent/CA2104398A1/en not_active Abandoned

Non-Patent Citations (1)

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