Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
  • C01D15/00—Lithium compounds
  • C01D15/08—Carbonates; Bicarbonates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J39/00—Cation exchange; Use of material as cation exchangers; Treatment of material for improving the cation exchange properties
  • B01J39/04—Processes using organic exchangers
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
  • C01D15/00—Lithium compounds
  • C01D15/04—Halides

Definitions

• the present invention relates to a method for producing a high-purity lithium salt starting from lithium carbonate, in which an aqueous mixture containing lithium hydrogen carbonate is subjected to a treatment by means of an ion exchanger module.
• lithium salts such as lithium fluoride (LiF) or lithium chloride (LiCl), are generally used, which in turn are obtained from lithium carbonate (Li 2 CO 3 ).
• LiF lithium fluoride
• LiCl lithium chloride
• these must already have a very high purity. It is particularly desirable that the foreign metal ion content is 1 ppm or less.
• DE-A 195 41 558 describes a process for cleaning lithium chloride solutions, the main focus being on the removal of undesired sodium chloride contents.
• lithium chloride solutions are obtained there by evaporation with yields of> 99%, these being essentially free of sodium chloride.
• the lithium chloride solutions obtained have a content of less than 0.3% by weight of sodium chloride.
• the example according to the invention described there has an NaCl content of 0.2%.
• the present invention relates to a process for producing a high-purity lithium salt starting from lithium carbonate, which comprises the following stages A to D: - 3 -
• step C Precipitation of lithium carbonate from the mixture obtained in step B and containing lithium hydrogen carbonate treated by means of an ion exchanger module, and
• the process according to the invention starts from lithium carbonate, which is dispersed in water or in a water-containing solvent mixture with, for example, an alcohol, a ketone or aldehyde and is converted into water-soluble lithium hydrogen carbonate by means of CO 2 .
• concentration of lithium carbonate / lithium hydrogen carbonate in the respective aqueous mixture is about 0.5 to about 30, preferably about 3 to about 20,% by weight.
• stage B The aqueous mixture containing lithium hydrogen carbonate thus obtained is then subjected to a treatment with an ion exchanger module (stage B).
• this stage B is preferably carried out at approximately 10 to approximately 70 ° C., more preferably at approximately 20 to approximately 40 ° C.
• Steps A and B are preferably carried out at superatmospheric pressure, since then higher LiHCO 3 concentrations can be achieved.
• ion exchange resins are used.
• Such ion exchange resins preferably consist of organic polymers which have ion-active side chains, such as sulfo or carboxyl groups.
• all polymer-based ion exchangers i.e. both weakly and strongly acidic cation exchangers are used.
• devices such as e.g. a column filled with the above-described cation exchangers in the form of powder, pearls, granules, etc. can be used.
• Copolymers of styrene and divinylbenzene are particularly suitable as the polymeric base material for such ion exchangers.
• Resins of the trade name Lewatit ® such as Lewatit OC 1060 ® (AMP-type), Lewatit ® TP 208 (IDA-type), Lewatit ® E 304/88, Lewatit ® TP 207, Lewatit S 100 ®;
• Amberlite ® such as Amberlite ® IR 120, Amberlite ® IRA 743;
• Duolite ® those which are sold under the trade name Duolite ® , such as Duolite ® C 20, Duolite ® C 467, Duolite ® FS 346; and
• Imac ® such as Imac ® TMR, Lewatit ® types being preferred. More preferably regenerated and thus relatively low sodium ion exchange resins from the Lewatit ® type, or used other low-sodium ion exchange resins.
• stage B After passing through stage B, which in the case of heavily contaminated lithium carbonate or hydrogen carbonate or to obtain particularly pure lithium compounds, stage B can be repeated several times, i.e. two to five times, preferably two to three times.
• stage C lithium carbonate is again precipitated in stage C from the solution obtained in stage B, which can be achieved either by increasing the temperature, preferably to the boiling point of the solution, and / or reducing the CO 2 partial pressure.
• the temperature in stage C is generally about 80 to about 100 ° C.
• a stage D the lithium carbonate purified in this way is either worked up directly, ie essentially separated, preferably filtered off, if necessary. washed with H 2 O or a solvent containing H 2 O and dried and / or recrystallized again, stages A and C then being carried out again, or converted into the desired salt in each case using the appropriate reagents, such as, for example, aqueous hydrofluoric acid or hydrochloric acid .
• the lithium carbonate obtained in this way generally has a foreign metal ion content of less than 10 ppm, preferably less than 5 ppm and in particular less than 1 ppm and a chloride content of less than 30 ppm, preferably less than 10 ppm and in particular less than 5 ppm. - 6 -
• the precipitated lithium carbonate is dispersed in water and converted to LiF with aqueous hydrofluoric acid.
• the LiF is obtained as a solid and can be obtained in pure form as a solid by filtration and subsequent drying. CO 2 escapes as a gas.
• the latter in particular are outstandingly suitable for use as conductive salts, LiPF 6 , LiPf 4 and LiBf 4 being preferred in turn.
• Stage A semi-continuously, ie the dispersion comprising water and Li 2 CO 3 is introduced and CO 2 is introduced; - 7 -
• the process according to the invention has the particular advantage that both alkali cations, in particular sodium ions, and polyvalent cations, such as, for example, alkaline earth metal and transition metal ions, can be removed very well; by means of the method according to the invention, the sodium concentration in Li 2 CO 3 can be reduced by a factor of up to more than 400; Contamination by polyvalent ions, such as calcium, magnesium, iron and / or aluminum, are practically completely removed by treatment with an ion exchanger according to stage B. In addition, the product obtained is essentially free of chloride.
• the resulting solution was filtered and pumped by a pump through an ion exchange bed with regenerated Lewatit ® TP 207 (100 ml) and rinsed with 100 ml water.
• the dosage via Lewatit ® TP 207 was 400 ml / h.
• the solution obtained after passing through the ion exchanger bed was then boiled under reflux, the lithium hydrogen carbonate being converted into lithium carbonate with elimination of CO 2 and precipitating out.
• the total yield of LiF, based on the amount of Li 2 CO 3 used, is 66.4%.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Inorganic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Secondary Cells (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Inorganic Compounds Of Heavy Metals (AREA)

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Cited By (4)

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Citations (5)

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• 1998
  • 1998-03-05 DE DE19809420A patent/DE19809420A1/de not_active Ceased
• 1999
  • 1999-03-01 CA CA002322544A patent/CA2322544A1/en not_active Abandoned
  • 1999-03-01 WO PCT/EP1999/001322 patent/WO1999044941A1/de not_active Ceased
  • 1999-03-01 US US09/623,110 patent/US6592832B1/en not_active Expired - Fee Related
  • 1999-03-01 JP JP2000534495A patent/JP2002505248A/ja not_active Ceased
  • 1999-03-03 TW TW088103201A patent/TW440543B/zh not_active IP Right Cessation

Patent Citations (5)

Non-Patent Citations (3)

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