Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B1/00—Electrolytic production of inorganic compounds or non-metals
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B1/00—Electrolytic production of inorganic compounds or non-metals
  • C25B1/01—Products
  • C25B1/135—Carbon
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B15/00—Operating or servicing cells
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
  • C25B9/40—Cells or assemblies of cells comprising electrodes made of particles; Assemblies of constructional parts thereof

Definitions

• the present invention relates to; a process for the production of metal hydroxides and / or metal carbonates by anodic dissolution of corresponding metals and precipitation of the hydroxides or basic carbonates in an aqueous medium.
• Metal hydroxides or basic metal carbonates are usually prepared by precipitation from corresponding aqueous metal salt solutions by reaction with alkali metal hydroxides or alkali metal hydrogen carbonates. This produces stoichiometric amounts of neutral salts that have to be worked up or disposed of.
• EP-A 684 324 it was proposed to circulate anolyte and catholyte circuits separated in a two-chamber electro cell divided by an anion-active ion exchange membrane, nickel being anodically dissolved in the anode chamber, the anolyte containing ammonia as a complexing agent, and hydroxyhones being generated in the cathode chamber and through the membrane into the anode chamber are transferred in which anolytes are hydrolyzed by increasing the temperature, the nickel-amine complexes and nickel hydroxide is precipitated and separated from the anolyte.
• the process allows the particle size of the nickel hydroxide to be controlled over a wide range by controlling the hydrolysis process. However, the process is costly and prone to failure due to the still inadequate service life of commercially available membranes.
• the object of the invention is to provide a process for the production of metal hydroxides which does not have the disadvantages mentioned.
• the method according to the invention also allows the production of basic metal carbonates essentially without the generation of neutral salt.
• Metal salt solution and an alkaline alkali salt solution can be obtained by cathodic hydrogen evolution, which are combined in a second stage for the precipitation of the metal hydroxide.
• the alkali metal salt solution obtained after separation of the metal hydroxide precipitation product is returned to the electrolysis cell. This is achieved by using a three-chamber electrolysis cell, in which the chambers are separated by porous membranes, by introducing an alkali salt solution into the intermediate chamber between the cathode and anode chambers.
• carbon dioxide is additionally introduced into the cathode chamber or into the precipitation reactor of the second stage, basic carbonates are obtained.
• the present invention accordingly relates to a process for the production of metal hydroxides or basic metal carbonates by anodic dissolution of corresponding metals and precipitation of the hydroxides or basic carbonates in an aqueous medium, which is characterized in that the anodic dissolution of the metal component takes place in the anode chamber of a three-chamber electrolysis cell, arranged between the anode chamber and cathode chamber and by an aqueous auxiliary salt solution is continuously fed to this intermediate chamber, separated by porous membranes, an at least non-alkaline metal salt solution is continuously withdrawn from the anode chamber, an alkali auxiliary salt solution is continuously withdrawn from the cathode chamber, and the at least non-alkaline metal salt solution and the alkaline auxiliary salt solution outside the
• Electrolysis cell for the precipitation of metal hydroxides or basic metal carbonates are combined.
• Solution with a complexing agent e.g. a Nö ⁇ solution for the production of spherical precipitation products are supplied.
• Basic metal carbonates are obtained in a simple manner so that carbon dioxide is introduced either into the cathode chamber or into the combined precipitation solution.
• Suitable metals are those which form salts soluble in the aqueous medium, which can be precipitated as hydroxides and / or basic carbonates in neutral or alkaline medium and which, when switched as an anode in the electrolysis cell, do not form non-conductive surface layers (oxides).
• Fe, Co, Ni, Cu, In, Mn, Sn, Zn, Cd and / or Al are particularly preferably used as metals.
• Nickel or cobalt anodes are preferably used.
• Chlorides, nitrates, sulfates, acetates and / or formates of the alkali and / or alkaline earth metals are suitable as auxiliary salts to be introduced into the intermediate chamber of the electrolytic cell.
• Sodium chloride and sodium sulfate are preferred.
• the auxiliary salt solution preferably has a concentration of 1 to 3 mol / 1.
• the auxiliary salt solution introduced into the intermediate chamber flows through the porous
• auxiliary salt solution is preferably introduced into the intermediate chamber at a pressure such that the flow rate through the porous membranes is greater than that
• the inflow rate of the electrolyte must be selected such that the ions with de r higher mobility in any case be prevented from entering the central area.
• the ratio of anions to cations of the auxiliary salt solution which passes through the membrane to the anode side is approximately 1.5 to 3 and conversely the ratio of cations to anions of the auxiliary salt solution which passes through the membrane to the cathode chamber is approximately 1.2 to 3.
• auxiliary saline solution introduced into the intermediate chamber passes through the porous membranes.
• Porous, preferably woven cloths or nets are suitable as membranes, which consist of materials that are resistant to the auxiliary salt solutions, the anolytes and the catholytes.
• Suitable wipes preferably have a pore radius of 10 to 30 ⁇ m. The porosity can be 20 to 50%.
• the auxiliary salt solution with excess anions which passes into the anode compartment from the central compartment is essentially neutralized by the anodic dissolution of the metal anode and is continuously discharged as anolyte.
• a small amount of acid can be fed into the anode chamber, preferably by feeding in an acid which contains the anion of the auxiliary salt solution.
• the anolyte running out of the anode chamber preferably has a metal salt content of 0.5 to 2 mol / 1. Hydrogen and OH "ions are formed on the cathode in accordance with the excess of cations of the auxiliary salt which has passed through the membrane to the cathode compartment. An alkaline auxiliary salt solution thus overflows from the cathode chamber (catholyte).
• Anolyte and catholyte are then brought to the precipitation reaction in a precipitation reactor.
• a hydroxide solution can optionally be added and, if necessary, complexing agents such as ammonia can be added in order to achieve a spherical form of the precipitation products.
• carbon dioxide is fed into the catholyte or directly into the precipitation reactor.
• an optionally alkaline auxiliary salt solution remains which, after neutralization, is preferably returned to the intermediate chamber of the electrolysis. It is also possible to store the anolyte and catholyte in intermediate containers and to carry out the precipitation discontinuously.
• corresponding metal salt solutions of salts of the doping metals can be introduced into the precipitation reactor, the demand for alkali hydroxide supplied to the precipitation reactor for adjusting the precipitation pH to increase molarly in accordance with the amount of the doping salts. It this creates a corresponding excess of neutral salt, which cannot be returned to the intermediate chamber of the electrolytic cell.
• composition corresponds or, but in separate three-chamber electrolysis cells to produce the respective metal salt components separately.
• the precipitation reaction can also be controlled by the presence of complexing agents, for example ammonia, in the precipitation reactor.
• complexing agents for example ammonia
• spherical nickel hydroxides are obtained by introducing ammonia into the precipitation reactor.
• -Amphoteric doping metals e.g. Aluminum can be introduced into the catholyte as aluminum salt or aluminates.
• the precipitation product is separated from the combined auxiliary salt solution (mother liquor). This can be done by sedimentation, by means of cyclones, by centrifugation or filtration. The separation can take place in stages, the precipitate being obtained fractionally by particle size. Furthermore, it may be expedient to return part of the mother liquor to the precipitation reactor as crystallization nuclei after the large metal hydroxide particles have been separated off with the small metal hydroxide particles.
• the mother liquor freed from the precipitate is returned to the intermediate chamber of the three-chamber electrolysis cell, if appropriate after working up.
• the processing serves to remove residual metal ions, to prevent the accumulation of impurities and to re-establish the concentration and composition of the auxiliary salt solution, for example stripping any complexing agent which may be introduced for precipitation.
• the mother liquor can be worked up in the partial stream.
• the process is insensitive to the processing of the auxiliary salt solution. It is generally harmless if the complexing agent is returned to the intermediate chamber with the mother liquor.
• the process is also carried out by introducing small amounts of metal ions into the
• Flexibility results from the electrolytic separation of a recirculable, neutral auxiliary salt solution into an acidic and alkaline fraction as it passes through robust porous, electrochemically inactive membranes. In this way, it is possible to remove the metal ions and the hydroxide ions in the form of separate solutions from the electrolysis cell and to reunite them only for the precipitation. As a result, the precipitation can be controlled independently, without any influence on or retroactivity through the electrolysis process.
• the process according to the invention provides an extremely flexible process for the production of metal hydroxides or basic carbonates.
• the person skilled in the art is readily able to make further variations, each adapted to the special requirements of the manufacture of a special product.
• accepting slightly higher pressures in the intermediate chamber it is possible to use multilayer filter cloths to make the conductive salt / anion / cation ratio that passes over to the anolyte or catholyte more favorable.
• the middle space can also be separated on the cathode and anode side by different separation media (filter cloths, diaphragms, etc.) to enable different flow conditions (velocities) in the cathode and anode space.
• filter cloths, diaphragms, etc. to enable different flow conditions (velocities) in the cathode and anode space.
• the electrodes can be arranged concentrically as in a tube capacitor.
• the counter electrode In the middle of a cylindrical cell there is a cylinder electrode, the counter electrode is designed as a tube concentric with this central electrode.
• the tubular space between the two electrodes In the tubular space between the two electrodes is the also concentrically arranged middle space, which consists of two parallel tubular filter cloths, diaphragms or the like. Separation media is formed.
• the invention further relates to a device for producing metal hydroxides, comprising a three-chamber electrolysis cell, a precipitation reactor and means for separating solids from the outlet of the precipitation reactor, the electrolysis cell being divided by porous membranes in an anode chamber, an intermediate chamber and a cathode chamber, an inlet to the intermediate chamber, has an outlet from the anode chamber and an outlet from the cathode chamber, an inlet of the precipitation reactor is connected to the outlet from the anode chamber and a further inlet of the precipitation reactor is connected to the outlet from the cathode chamber.
• the cathode chamber also has a discharge for hydrogen generated cathodically. Furthermore, supply options for subordinate quantities Auxiliary reagents such as acid in the anode chamber, base in the precipitation reactor, both for pH adjustment, and complexing and doping agents can be provided in the precipitation reactor.
• FIG. 1 The invention is explained in more detail with reference to the attached FIG. 1:
• FIG. 1 shows schematically the three-chamber electrolysis cell 1, the precipitation reactor 2 and the separation device 3 for the precipitation product.
• the electrolytic cell 1 is divided by the porous membranes 13 and 14 into the anode chamber A, the intermediate chamber I and the cathode chamber K.
• the anode chamber In the anode chamber is the anode 11, which consists of the metal to be anodically dissolved;
• the cathode K which is resistant to the alkaline auxiliary salt solution, is located in the cathode chamber.
• a neutral auxiliary salt solution is introduced via line 40 into the intermediate chamber I by means of a flow-controlled pump 46.
• K flows a constant current with current densities of 300 to 1200 A / m 2 .
• An essentially neutral or weakly acidic auxiliary salt and anode metal salt-containing solution overflows from the anode chamber A via line 41.
• An alkaline auxiliary salt solution runs out of the cathode chamber via line 42.
• Hydrogen is discharged from the head of the cathode chamber via line 15.
• acid can be fed into the anode chamber via line 16.
• carbon dioxide can be introduced via line 17 for the production of basic metal carbonates.
• the processes 41 and 42 from the electrolysis cell 1 are introduced into the precipitation reactor 2.
• the precipitation reactor contains, for example, a high-speed stirrer
• the precipitation reactor can also be used as a loop or jet reactor or in be of a different design.
• the precipitation suspension overflows from the precipitation reactor in line 43.
• introducing devices 22, 23 and 24 can be provided to provide auxiliary and modifying means, such as for pH adjustment, doping and / or influencing the precipitation by introducing complexing agents or introducing CO 2 for the production of basic carbonates.
• the precipitation reactor 2 can also be designed as a reactor cascade, partial streams of the electrolysis cell outlets 41 or 42 being introduced into the individual reactors of the cascade.
• the precipitation suspension passes via line 43 into the separating device 3 shown here as a hydro-cyclone, from which the precipitated solid is largely drawn off via the underflow 31 and the precipitated mother liquor freed from solids overflows for working up 45 via line 44.
• Arrow 48 schematically indicates the introduction of work-up reagents and the removal of any interfering components.
• the processed mother liquor can via line 47 and pump
• An electrolysis cell as shown schematically in FIG. 1, was used.
• the anode and cathode areas were 7.5 dm 2 each.
• the distance between the electrodes was 4 cm.
• the porous membranes used were polypropylene wipes with an average pore diameter of 26 ⁇ m and a porosity of 28% calculated from the density determination of the wipe, as are available from SScapa Filtration GmbH (Propex E14K).
• the anode was made of pure nickel.
• a nickel electrode was also used as the cathode. 8.18 l of sodium chloride solution containing 80 g / l of sodium chloride were fed to the intermediate chamber of the cell. Furthermore, 25 ml of a 1 normal hydrochloric acid solution were introduced into the anode compartment every hour.
• the anodic current was 1000 A / m 2 .
• a voltage of 7.3 V was measured between the anode and the cathode. After reaching the steady state, 3.67 l of anolyte overflow from the anode chamber and 4.53 l of catholyte overflow from the cathode chamber.
• the alkaline mother liquor was introduced into a stripping column in order to remove the ammonia, then re-roused and returned to the storage container from which the auxiliary salt solution is removed.
• the electrochemical mass utilization showed at least 100% in standard half-cell tests.
• Example 1 was repeated with the difference that an auxiliary salt solution was used which contains 4.5 g / 1 NH 3 in addition to 80 g / 1 NaCl.
• the introduction of ammonia solution into the precipitation reactor was dispensed with.
• Example 2 was repeated with the difference that additional cobalt and zinc electrodes were placed in the anode chamber and these were subjected to currents which correspond to the desired molar ratio of Co and Zn in the nickel hydroxide.
• the processing of the mother liquor from the precipitation reactor consisted only of adding used water.

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• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
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• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)

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• 2000
  • 2000-06-19 DE DE10030093A patent/DE10030093C1/de not_active Expired - Fee Related
• 2001
  • 2001-06-06 WO PCT/EP2001/006420 patent/WO2001098559A1/de not_active Ceased
  • 2001-06-06 PT PT1943480T patent/PT1297199T/pt unknown
  • 2001-06-06 JP JP2002504703A patent/JP4801312B2/ja not_active Expired - Lifetime
  • 2001-06-06 CN CNB018114431A patent/CN1220793C/zh not_active Expired - Lifetime
  • 2001-06-06 CA CA002412927A patent/CA2412927C/en not_active Expired - Lifetime
  • 2001-06-06 EP EP01943480.2A patent/EP1297199B1/de not_active Expired - Lifetime
  • 2001-06-06 KR KR1020027017150A patent/KR100809121B1/ko not_active Expired - Lifetime
  • 2001-06-06 US US10/311,396 patent/US7048843B2/en not_active Expired - Lifetime
  • 2001-06-06 ES ES01943480.2T patent/ES2612928T3/es not_active Expired - Lifetime
  • 2001-06-06 CZ CZ20024119A patent/CZ300272B6/cs not_active IP Right Cessation
  • 2001-06-06 AU AU2001266051A patent/AU2001266051A1/en not_active Abandoned
  • 2001-06-18 MY MYPI20012859A patent/MY140696A/en unknown
  • 2001-06-19 TW TW90114782A patent/TW572844B/zh not_active IP Right Cessation

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