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
  • C01D15/02—Oxides; Hydroxides
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/80—Compositional purity

Definitions

• the invention relates to a method for the production of lithium hydroxide through crystallization of lithium hydroxide monohydrate from a solution of lithium nitrate.
• lithium hydroxide as monohydrate or anhydrous in highly pure form is recently in particular demand.
• the reaction product is leachable with water and provides a solution of lithium sulfate with concentrations of 15 - 25 g/L (approx. 1.0 - 1.5 mol/L Li 2 SO 4 )
• Lithium sulfate-containing solutions are also produced during the processing of sulfate-rich brines from salt lakes such as in the Salar de Uyuni or the Atacama (NPL1 ). Generally, lithium is recovered from these salt lakes as chloride, if sufficient calcium chloride-containing solutions are available for the separation of sulfate as gypsum. For brines with high sulfate contents, the isolation of pure lithium sulfate as an intermediate has also been considered (NPL1 ).
• Lithium sulfate-containing solutions are also produced in recycling processes of lithium batteries when the materials are leached with sulfuric acid.
• lithium hydroxide solution and insoluble calcium carbonate it is possible to precipitate lithium from solutions of easily soluble lithium salts such as sulfate or chloride as lithium carbonate and subsequently react the same with calcium hydroxide to form lithium hydroxide solution and insoluble calcium carbonate.
• Outotec has recently presented a process for the production of lithium hydroxide which is based on a two-step alkaline leaching.
• lithium is extracted from silicate minerals in a pressure leaching using sodium carbonate.
• the reaction leads to the formation of soluble lithium carbonate and the mineral component analcime (NaA ⁇ Oe FW) as main components.
• lithium carbonate is solubilized in a conversion reaction to form a lithium hydroxide solution and solid calcium carbonate; see NPL4 (Tiihonen, Marika; Haavanlammi, Liisa et al.: chiefOutotec Lithium Hydroxide Process - A novel direct leach process for the production of battery grade lithium hydroxide monohydrate from calcined spodumen", published in ..Hydrometallurgy Newsletter 1/2019“ on https://www.outotec.com/products-and-services/newsletters/hydrometallurgy-newsletter/)
• Various easily soluble calcium salts can be used in order to precipitate and separate the sulfate in the form of a poorly soluble calcium sulfate (gypsum, hemihydrate, anhydrite) from lithium sulfate-containing solutions, e.g. with calcium nitrate solution according to reaction (2) as proposed in PTL3 (CN 102602967 A).
• the filtrate then each contains lithium combined with the anion of the easily soluble calcium salt used for precipitation, in the case mentioned the nitrate ion. Formate, , acetate, citrate, bromide etc. can be used as further anions.
• the resulting lithium salt solution is suitable for the further processing to lithium hydroxide.
• no double salts should form with lithium.
• the anions of the added calcium salt must not adversely affect other process stages of LiOH production.
• reaction of sodium hydroxide with lithium nitrate is carried out at such a high lithium concentration of 150-180 g/L that not all lithium nitrate can be dissolved, i.e. the reaction (3) proceeds in a suspension of solid and solution from start to the finish. Reaction temperatures of 60 °C, 70 °C and 80 °C and crystallization times of 5 hours, 4 hours and 6 hours are taught.
• NPL1 Garrett, D. E. Handbook of Lithium and Natural Calcium Chloride, Elsevier Ltd., Amsterdam, 2004.
• NPL2 Tong, T.; Elimelech, M. Environ. Sol. Techno/., 2016, 50, 6846-6855.
• NPL3 Grageda, M. et al. Energy 2015, 89, 667-677.
• NPL4 Tiihonen, Marika; Haavanlammi, Liisa et al.: perennialOutotec Lithium Hydroxide Process - A novel direct leach process for the production of battery grade lithium hydroxide monohydrate from calcined spodumen", published in ..Hydrometallurgy Newsletter 1/2019 on https://www.outotec.com/products-and- services/newsletters/hydrometallurgy-newsletter/
• Object of the invention is to provide an economical and efficient process for the production of lithium hydroxide in high yield and purity.
• the present invention was made in view of the mentioned disadvantages of the prior art.
• the present invention relates to
• Process according to item 8 further comprising a step of, after the leaching, removing at least one impurity selected from heavy metals, aluminum, magnesium, sulfate and carbonate from the obtained lithium sulfate-containing solution by usual purification processes.
• Process according to any one of items 6 to 10, comprising a further step wherein, after step i), unreacted calcium nitrate is reacted with lithium carbonate or sodium carbonate in order to form and precipitate calcium carbonate, and the same is separated from the remaining lithium nitrate-containing solution.
• Process according to any one of items 2 to 11 further comprising a step of generating the sodium hydroxide hydrate melt in a separate reactor from NaOH in solid form (e.g. pellets) and water at temperatures above 60 °C, where the water content is preferably determined such that the concentration of nitrate mentioned in item 3 can be obtained.
• Process according to any one of items 1 to 12, wherein the approximately stoichiometric amount of the sodium hydroxide in step b) is from 0.9 mol to 1.1 mol NaOH per mol lithium nitrate, preferably from 0.95 mol to 1.05 mol NaOH per mol lithium nitrate, more preferably 1.0 mol NaOH per mol lithium nitrate.
• An advantage of the process of the invention is that the formation and crystallization of lithium hydroxide monohydrate proceeds within a relatively short period of time and yet a high lithium yield is obtained.
• a further advantage of the invention lies in that lithium hydroxide monohydrate is obtained in high purity, without the need for a further purification step, e.g., recrystallization.
• the process of the invention is distinguished from the known process for the production of lithium hydroxide in that energy-intensive cooling steps are not necessary. Further advantages result from the following detailed description.
• a preferable and advantageous aspect of the process of the invention is that the lithium hydroxide monohydrate is crystallized from a lithium nitrate-containing solution (i.e.
• Fig. 1 is a schematic depiction of a preferable embodiment of the process of the invention, wherein a powder from the “acid roast” process is used as starting material for the production of lithium hydroxide.
• hydrate melt is generally understood to mean liquids that result from the melting of salt hydrates or metal hydroxide hydrates in their own crystal water, e.g. LiNO 3 3H 2 O, Ca(NO 3 ) 2 -4H 2 O, and NaOH H 2 O.
• the water contents are generally between 1 - 6 mol H 2 O per mol salt or metal hydroxide, and do not have to correspond exactly to the contents of the crystalline hydrates.
• Solutions of salts with water contents that do not form crystalline hydrates, such as NaNO 3 are also named or characterized as salt hydrate melts (also see H.-H. Emons, Th. Fanghanel, R. Naumann, W. Voigt, volunteerSalzhydratschmelzen“; Wegungsberichte der Akademie dermaschineen der DDR, 3N/1986, Akademie-Verlag Berlin).
• a solution essentially consisting of lithium nitrate and unavoidable impurities is preferably used as lithium nitrate-containing solution.
• the content of lithium nitrate, with respect to all dissolved solids, is preferably at least 95.0 wt.-%, more preferably at least 97.0 wt.-%, e.g. at least 99.0 wt.-%.
• the content of metal salts that can be precipitated with hydroxide should preferably be less than 0.25 wt.-%, particularly less than 0.1 wt.-%.
• Some of the impurities that may be present in larger amounts, since they are less likely to affect the purity of the lithium hydroxide product, are NaNO 3 or KNOs.
• solution is understood as aqueous solution, unless otherwise stated.
• the source of the lithium nitrate-containing solution is not particularly limited.
• a suitable source are lithium nitrate-containing solutions, which were obtained by dissolving lithium battery wastes (with nitric acid) and, optionally, subsequent purification steps.
• the lithium nitrate-containing solution can be generated by dissolving lithium carbonate with correspondingly concentrated nitric acid. This offers the possibility of recycling the lithium carbonate, which can be obtained at the end of the process by introducing CO 2 into the liquid obtained by washing the crystallizate, into the process.
• the lithium nitrate-containing solution is preferably obtained by conversion of a lithium sulfate-containing solution.
• the lithium sulfate-containing solution can be reacted with calcium nitrate according to reaction (2), in order to form lithium nitrate and calcium sulfate and precipitate the calcium sulfate.
• step a) If one starts from a lithium sulfate-containing solution, it is preferred according to the invention to provide the lithium nitrate-containing solution used in step a) in a process comprising the followings steps: (i) generating a lithium nitrate-containing solution with a concentration of at least 3.5 mol/L lithium, preferably at least 4.0 mol/L lithium, e.g. within the range of 3.5 - 6.0 mol/L lithium, from a lithium sulfate-containing solution by reacting with calcium nitrate, preferably a calcium nitrate hydrate melt, at a temperature of 10 to 100 °C, preferably 50 - 70 °C,
• sulfate is produced as calcium sulfate, which can be sold on and used for example as gypsum in the building materials industry. In contrast to known processes for the production of lithium hydroxide, less byproducts are formed that must be stored in landfills.
• the calcium nitrate is used in at least the stoichiometrically required amount for the reaction of the lithium sulfate, preferably in a 1% to 10% excess with regard to the amount stoichiometrically required.
• the calcium nitrate can be in solid or liquid form, preferably in liquid form as hydrate melt.
• the added calcium nitrate hydrate melt usually has a temperature of 40 °C to 70 °C.
• the calcium nitrate hydrate melt may contain water in an amount of 3 - 4 mol H 2 O per mol Ca(NO 3 )2.
• the reaction can be carried out at a temperature of 10 - 100 °C, preferably 50 - 70 °C.
• the reaction can also be carried out at a temperature of 20 - 40 °C.
• the reaction mixture is preferably thoroughly mixed when the calcium nitrate is added (preferably as salt hydrate melt).
• the advantage of adding a salt hydrate melt is that a good mixing is achieved, without having to add the calcium nitrate as solution, which would undesirably increase the water content of the resulting lithium nitrate-containing solution.
• the source of the lithium sulfate-containing solution is not particularly limited, and the lithium sulfate-containing solution can originate from usual processes for producing lithium sulfate from lithium-containing minerals or salts or the recycling process of lithium ion batteries.
• the lithium sulfate-containing solution is preferably obtained from the roast product of betaspodumene in the presence of sulfuric acid (“acid roast” process) and subsequent leaching (with water or dilute aqueous solutions, e.g. washing solution from downstream process stages).
• the lithium sulfate solution can be subjected to usual purification processes after leaching, or these purification steps can be carried out only after the conversion into a LiNO 3 solution, i.e.
• steps i), iii are, for example, a step-by-step pH increase by base addition to precipitate aluminum, iron, manganese etc., a fine purification by precipitation of sulfate as BaSO 4 and carbonate as BaCO 3 or the inclusion of ion exchange processes.
• a base e.g. sodium hydroxide, calcium hydroxide
• a fine purification of sulfate and carbonate can be carried out by precipitation as BaSO 4 and BaCO 3 , respectively, by adding Ba(OH) 2 or Ba(NO 3 ) 2 .
• an ion-exchanger In order to remove remaining aluminum, magnesium, calcium, but also heavy metals, such as iron or manganese, an ion-exchanger can be also used.
• the pH is preferably adjusted to 4 - 7, preferably 5 - 6.
• the concentration of lithium sulfate in the lithium sulfate-containing solution used in step a) is preferably at least 1.5 mol/L, more preferably 2.0 mol/L, e.g. at least 2.4 mol/L.
• This concentration gives a lithium nitrate-containing solution with preferably at least 3.0 mol/L, more preferably at least 4.0 mol/L lithium, e.g. at least 4.8 mol/L.
• the concentration of the lithium sulfate in the lithium sulfate-containing solution is preferably well below the solubility of lithium sulfate and preferably no more than 3.0 mol/L.
• U2SO4 concentrations are within the range of 1 - 1.5 mol/L. If the preferred minimum concentration of U2SO4, i.e. at least 1.5 mol/L, preferably 2.0 mol/L, is not achieved by the leaching process, U2SO4 from other sources can be added. Alternatively or additionally, the content of U2SO4 in the H2SO4 solution obtained by the leaching of the “acid roast” product can be also generated in situ by neutralization of excess H 2 SO 4 with Li 2 CO 3 . This process variant offers a further option for circulation. Lithium carbonate can be obtained at the end of the process from the crystallizate washing liquid by introducing CO 2 . Therefore, in a process variant, the formed lithium carbonate can be reacted with sulfuric acid to lithium sulfate and used in the above step i).
• the calcium sulfate precipitated by the reaction (2) is separated from the lithium nitratecontaining solution (step ii).
• the separation techniques used for the CaSO 4 separation e.g. filtration (vacuum, pressure), centrifugation, or thickener
• temperature and solution concentration solid content in the suspension and additives for morphology control are parameters that can be optimized by using the generally known principles of precipitation and crystallization.
• step iii After the precipitation and separation of the calcium sulfate (preferably as gypsum), optionally further purification steps can be used before the concentration increase in step iii).
• unreacted calcium nitrate in the lithium nitrate-containing solution can be reacted with lithium carbonate or sodium carbonate, in order to form and precipitate calcium carbonate.
• the calcium carbonate is then separated from the remaining lithium nitratecontaining solution.
• the remaining heavy metals and magnesium can be separated by the usual methods by pH value increase using alkali hydroxide and/or alkali carbonate.
• alkali carbonate sodium carbonate or lithium carbonate is preferably used.
• carbonate and sulfate can be precipitated and filtered off with barium hydroxide. If necessary, trace of multivalent metal ions can be further removed through a cation exchanger.
• the optionally purified LiNOs solution is preferably neutralized with HNO3.
• the resulting pH value is preferably within the range of 6.0 - 8.0, more preferably 6.5 - 7.5.
• step iii) the concentration of the lithium nitrate-containing solution is then brought to the desired concentration of lithium nitrate of 13.0 - 15.4 mol/kgw, preferably 13.5 to 15.4 mol/kgw, more preferably 14.0 to 15.0 mol/kgw. This takes place preferably by evaporation.
• lithium nitrate from other sources could be added or Li 2 CO 3 could be reacted with HNO 3 in situ to LiNOs, which can be also used for circulation for the reasons explained.
• step i) to Hi are preceded by the essential process steps a) to c
• the entire process from step i) to step c) preferably does not require any cooling steps with cooling liquids or gases, which cool down to temperatures below 20 °C, in particular no deep-cooling step to temperatures below 5 °C.
• cooling liquids or gases which cool down to temperatures below 20 °C, in particular no deep-cooling step to temperatures below 5 °C.
• this also applies to the preferred variant, which starts from “acid roast powder” as the starting material.
• Fig. 1 illustrates a possible embodiment of the present invention, wherein “acid roast powder” is used as starting material.
• the lithium sulfate in “acid roast powder” is leached with water, and the remaining silicate is filtered off from the lithium sulfate-containing solution (filtrate FL1 ).
• the silicate is washed with water once or multiple times, and the washing solution(s) (WF1 ) can be introduced again into the leaching step.
• the washed silicate can be landfilled or processed.
• the filtrate (FL1 ) is neutralized by addition of NaOH, soda or U2CO3, in order to form and precipitate iron- and aluminum hydroxide.
• the precipitated iron and aluminum hydroxides are filtered off from the solution.
• Calcium nitrate is added to the lithium sulfate- containing filtrate (FL2), in order to form lithium nitrate and calcium sulfate by the reaction (2), where calcium sulfate (gypsum) precipitates.
• the calcium sulfate is for example filtered off and washed with water, and the washing solution(s) (WF2) can be combined with the washing solution(s) WF1 and introduced again into the leaching step.
• the washed calcium sulfate can be landfilled. It is however preferably prepared and sold for processing, e.g. in the building materials industry.
• the lithium nitrate-containing filtrate (FL3) in general contains still remaining calcium, sulfate and carbonate from the previous process.
• the calcium in filtrate (FL3) is precipitated as calcium carbonate by addition of alkali hydroxide and/or alkali carbonate and removed from the solution (FL4). Carbonate and sulfate are then precipitated and filtered off in the next step by addition of barium hydroxide or addition of Ba(NO 3 )2.
• the filtrate (FL5) is evaporated in order to achieve the preferred concentration of lithium of 14 - 15 mol/kgw.
• the obtained lithium nitrate-containing solution can be used further for the crystallization and separation steps as described below.
• Step b crystallization of lithium hydroxide monohydrate
• lithium hydroxide is formed by reaction (3) and lithium hydroxide monohydrate is crystallized, while sodium nitrate remains fully dissolved.
• the crystallization of lithium hydroxide monohydrate takes place by the addition of an approximate stoichiometric amount of sodium hydroxide, preferably in form of a hydrate melt, to this lithium nitrate-containing solution at a temperature within the range of 70 - 85 °C, preferably 75 - 85 °C.
• the approximate stoichiometric amount of sodium hydroxide is preferably 0.9 mol to 1.1 mol NaOH per mol lithium nitrate, more preferably 0.95 mol NaOH to 1.05 mol per mol lithium nitrate, particularly 1.0 mol NaOH per mol lithium nitrate.
• the reaction mixture is preferably supplied with an amount of water (in mol) which stoichiometrically corresponds to at least 50% of the amount of lithium ions (in mol) in the reaction mixture, preferably at least 70%, more preferably at least 80%.
• the preferred upper limit is 100%, since a dilution by unnecessary addition of water would reduce the yield of LiOH H 2 O.
• the amount and the type of the sodium hydroxide hydrate are controlled in view of the amount of water introduced into the reaction mixture.
• the preferred ranges given above for the amount of water are considered to this end.
• the nitrate concentration in the reaction mixture can also be adjusted.
• the amount and the type of the sodium hydroxide hydrate is preferably selected, such that, after the addition of the sodium hydroxide hydrate, the nitrate concentration, i.e. the total concentration of lithium nitrate and sodium nitrate, is within the range of 13.0 - 15.4 mol/kgw, preferably 13.5 - 15.4 mol/kgw, more preferably 14.0 - 15.0 mol/kgw.
• the nitrate concentration i.e. the total concentration of lithium nitrate and sodium nitrate
• the nitrates remain dissolved before and after the reaction with NaOH, i.e. the lithium nitrate before the reaction and the sodium nitrate after the reaction. This contributes to the purity of the final product.
• the sodium hydroxide hydrate melt can be generated in a separate reactor from NaOH in solid form (e.g. pellets) and water at temperatures above 60 °C.
• the water content is preferably measured as described above.
• the heat of hydration of the NaOH is sufficient, in order to achieve the required temperatures above 60 °C.
• the formed lithium hydroxide monohydrate is separated from the sodium nitrate-containing solution by usual methods, such as centrifugation or filtration (e.g. pressure filtration) and optionally subsequently washed, preferably with little water.
• the separation of the lithium hydroxide monohydrate is carried out at the same temperature as in the step of the crystallization of lithium hydroxide monohydrate, i.e. within the range of 70 - 85 °C, preferably 75 - 85 °C.
• the steps b) and c) can be also denoted as “isothermal reaction”, since the temperature is kept after the start of the NaOH addition until the separation of the lithium hydroxide monohydrate within the range of 70 - 85 °C, preferably 75 - 85 °C. It is also preferred to keep temperature fluctuations as small as possible within this temperature range, preferably at ⁇ 5 0 C, in particular ⁇ 3 0 C.
• the obtained, usually still wet lithium hydroxide monohydrate is optionally washed with water, e.g. one or multiple times and in portions with a total amount that preferably does not exceed 0.2 kg of water per kg lithium hydroxide monohydrate.
• water instead of water, also a dilute LiOH solution could be used, preferably in the same amount.
• the lithium hydroxide monohydrate obtained by the process according to the invention achieves a typical battery quality without a further purification step, e.g. recrystallization.
• the content of LiOH in the obtained product is preferably at least 54 wt.-%, e.g. 54.8 - 56.5 wt.-%.
• the amount of impurities in the product is preferably less than 0.5 wt.-%, more preferably less than 0.3 wt.- %, further preferably less than 0.25 wt.-%, for example less than 0.2 wt.-%, less than 0.1 wt.- %, or less than 0.05 wt.-% and lies e.g.
• the content of CO 2 is preferably less than 0.5 wt.-%, particularly 0.035 - 0.35 wt.- %.
• the solution for example the centrifugate or filtrate, which is obtained after the separation of the lithium hydroxide monohydrate, still contains lithium.
• This solution which still has a temperature close to the temperature when leaving the LiOH reactor (approx. 70 - 85 °C, preferably 75 - 85 °C), can be directly reacted with carbon dioxide at this temperature, e.g. at a temperature of 65 to 80 °C, in order to form and precipitate lithium carbonate.
• the lithium carbonate can be used e.g. in the above described purification step, wherein excess calcium nitrate in the lithium nitrate-containing solution is reacted in order to form and precipitate calcium carbonate.
• the lithium from the lithium carbonate can, however, as described above, also be reintroduced (recycled) elsewhere into the process, for example as lithium nitrate after the reaction with nitric acid or after being sold.
• the solution which is obtained after the separation of the lithium hydroxide monohydrate and the precipitation of the Li 2 CO 3 , contains sodium nitrate as main component.
• the sodium nitrate can be crystallized by evaporation of the solution. Before the evaporation, the sodium nitrate-containing solution can be neutralized with nitric acid.
• Fig. 1 describes an example for the processing of the byproducts obtained.
• the solution (FL6) which is obtained after the separation of the lithium hydroxide monohydrate, is reacted with carbon dioxide in order to precipitate the remaining lithium as lithium carbonate.
• the lithium carbonate is filtered off and partially used in the step of the calcium removal. A further part or the remainder can be either sold or reacted with nitric acid to lithium nitrate.
• the washing solution (WF3) which is obtained by washing the lithium hydroxide monohydrate crystallizate, can be combined with the solution FL6 and then handled in the same way.
• the filtrate (FL7) which is obtained by filtration of lithium carbonate, can be neutralized by the addition of nitric acid and further evaporated, in order to crystallize sodium nitrate.
• the sodium nitrate is then filtered off.
• Fig. 1 also shows by way of example that the lithium nitrate obtained by reacting lithium carbonate and nitric acid can be reintroduced into the process between the evaporator and the LiOH crystallizer, i.e. to increase the concentration of the LiNOs-containing solution.
• the solution was subsequently made weakly acidic (pH value less than 7) by adding a small amount of nitric acid (HNOs) so that dissolved carbonate was expelled. If necessary, the solution can be passed through a cation exchange column, in order to remove traces of multivalent ions such as Ca 2+ or Mg 2+ . After the precipitation and separation of the calcium sulfate (gypsum) and the described purification steps, the Li concentration is at 4 mol/L.
• the purified lithium nitrate-containing solution with 4 mol/L Li which was obtained in Reference Example 1 , was brought to a concentration of 14.5 mol/kgw LiNOs by evaporation. The amount of solution was then 2 kg.
• the mixture was stirred at 80 °C and 600 rpm for further 60 minutes using a stirrer that is as tightly sealed as possible.
• the lithium hydroxide monohydrate formed was centrifuged off in a heated centrifuge at the same temperature. addition until the complete formation of the crystallizate.
• the crystallizate contained 81.4% of the lithium in the lithium nitrate solution used.
• the crystallizate was washed in the centrifuge 3 times with 30 ml_ of hot water each.
• the sodium content in the crystallizate fell below 0.1%.
• the lithium loss by washing the crystallizate, based on the initial content of the lithium nitrate solution used, was 2.3% and was determined by measuring the lithium content in the washing solution (WF3).
• suitable technical measures e.g. working under water vapour in the centrifuge chamber
• suitable technical measures are to be taken to ensure that no water evaporates from the filter cake and no crystallization of sodium nitrate takes place.
• the lithium carbonate formed was filtered off, the filtrate (FL7) was brought to a pH of 7 with concentrated HNO 3 and subsequently 80% of the water was evaporated and the remaining solution of the salt paste obtained was centrifuged off at 50 °C.
• the solution remaining after the centrifugation contains, in addition to NaNO 3 , a very small amount of LiNO 3 .
• the latter was formed by neutralization with HNO 3 .
• the centrifugate can be combined with the filtrate FL7 and evaporated. This recylization can continue until an acceptable value of LiNO 3 concentration is exceeded.
• Example 1 As in Example 1 , 797 g of hydrate melt of sodium hydroxide were produced in a separate container. The same was slowly poured into the concentrated lithium nitrate-containing solution and thereafter it was proceeded in the same manner as in Example 1 . The total yield of lithium hydroxide monohydrate after deducting the lithium loss by washing was 79%. The crystallization was complete after 60 minutes.
• Comparative Example 1 In the purified lithium nitrate-containing solution with 4 mol/L Li, which was obtained in Reference Example 1 , the lithium nitrate concentration was increased to 10 mol LiNO 3 per kg of water by evaporation followed by adding under stirring the stoichiometric amount of NaOH in pelletized form, whereby the temperature at the end of the reaction was 60 °C.
• the crystallizate was centrifuged off at 60 °C and washed directly in the centrifuge with a small amount of hot water to the required purity.
• the washing loss of LiOH H 2 O was 20 g of LiOH H 2 O, corresponding to 10.5% of the crystallized product, whereby the total yield fell to 62.5%.
• Example 1 was repeated, with the difference that the mixture obtained by addition of the NaOH hydrate melt was stirred at 70 °C and the lithium hydroxide monohydrate formed was centrifuged off in a heated centrifuge at the same temperature. The yield of the LiOH monohydrate decreased to less than 70%.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Inorganic Compounds Of Heavy Metals (AREA)
• Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=73059543

Family Applications (1)

Country Status (3)

Families Citing this family (5)

Family Cites Families (1)

• 2021
  • 2021-10-29 WO PCT/CA2021/051528 patent/WO2022094696A1/en unknown
  • 2021-10-29 EP EP21887939.3A patent/EP4240696A1/de active Pending
  • 2021-10-29 AR ARP210103007A patent/AR123954A1/es unknown

Also Published As

Similar Documents

Legal Events