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
  • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
  • C01F11/00—Compounds of calcium, strontium, or barium
  • C01F11/18—Carbonates
• • 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
  • C22B26/00—Obtaining alkali, alkaline earth metals or magnesium
  • C22B26/10—Obtaining alkali metals
  • C22B26/12—Obtaining lithium
• • 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
  • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
  • C22B3/02—Apparatus therefor
• • 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
  • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
  • C22B3/04—Extraction of metal compounds from ores or concentrates by wet processes by leaching
  • C22B3/12—Extraction of metal compounds from ores or concentrates by wet processes by leaching in inorganic alkaline solutions
• • 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
• • 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

Definitions

• CN102115101 discloses a method for producing lithium carbonate from spodumene mineral by performing a sulfuric acid treatment in order to obtain lithi- um sulfate, followed by a step of preparing the lithium carbonate mother liquor, from which the carbonate product can be separated, and finally the lithium hydrox- ide is obtained from the mother liquor by adding lime to causticize said mother liq- uor. Also barium hydroxide is said to be useful as a causticizing hydroxide.
• CN 1214981 C a similar process is described, wherein the step of adding sodium hydroxide into the lithium sulfate solution is carried out, followed by cooling and separating to obtain the liquid lithium hydroxide.
• the lithium hydroxide solution is then concentrated and crystallized, whereby a coarse lithium hydroxide monohydrate product can be separated.
• the pure lithium hydrox- ide monohydrate is obtained by reacting the coarse product with barium hydroxide, followed by concentrating and crystallizing.
• the lithium compound can be separated from the leaching re- action product, and the solution concentrated to the point of crystallization, where- after the mother liquor may be returned to the process.
• the method is not very effi- cient.
• Battery grade lithium hydroxide herein means lithium hydroxide mono- hydrate crystals having a purity of 56.5%, or higher of lithium hydroxide.
• the process concept is sulphate and acid free, without the formation of undesired crystallized byproducts.
• the objects of the invention are achieved by an arrangement and a method which are characterized by what is stated in the independent claims. Preferred embodiments of the invention are dis- closed in the dependent claims.
• the present invention relates to an arrangement for recovering lithium hydroxide from a fresh feed comprising a mineral raw material containing lithium or a raw material containing lithium carbonate, or a mixture of these, combined with a recycled solution and/or slurry, which arrangement comprises
• a pulping unit 1 for pulping the feed in the presence of water and alkali metal carbonate, in order to form a first slurry containing lithium
• a first leaching unit 2 for leaching said first slurry containing lithium, op- tionally combined with a recycled solution and/or slurry, at an elevated temperature, in order to form a second slurry containing lithium car- bonate
• a second leaching unit 3 for leaching said second slurry containing lithi- um carbonate, or a fraction thereof, in the presence of water and alkali earth metal hydroxide, in order to form a third slurry containing lithium hydroxide
• a solid-liquid-separation unit 31 for separating said third slurry contain- ing lithium hydroxide into solids that may be discarded, and a solution containing lithium hydroxide, and
• crystallising unit 4 for recovering lithium hydroxide monohydrate from a solution containing lithium.
• Said crystallization unit 4 is further connected to: one or more recycle lines 403,414,421,422 for carrying a solution and/or slurry from the crystallizing unit 4 to one or more upstream units including the pulping unit 1 , and optionally the first leaching unit 2.
• the arrangement compris- es also further necessary lines for carrying solutions, solids or slurries to their in- tended units.
• the present invention also relates to a method for recovering lithium hydroxide from a fresh feed comprising mineral raw material containing lithium or a raw material containing lithium carbonate, or a mixture of these, combined with a recycled solution and/or slurry.
• the method comprises the following steps of
• the mineral raw material containing lithium is selected from spodumene, petalite, lepidolite, micas or clays, or mixtures thereof, most suitably from spodumene.
• the mineral raw material containing lithium is selected from a mineral which has undergone heat treatment, whereby a particularly preferred material is beta-spodumene.
• a recycled solution and/or slurry can be used, containing lithium carbonate.
• said recycled solution and/or slurry is recycled from a downstream unit of the arrangement.
• said recycled solution and/or slurry is used in combination with fresh feed .
• the first leaching solution is separated from the solids after the first leaching step and is returned as a recycled solution either to the pulping step or to the first leaching step, or a frac- tion to each.
• a purifying step is carried out on the solution obtained from the solid/liquid separation step carried out after the second leaching.
• the solution and/or slurry obtained from the crystallization step, or from an optional pre- concentration step, preferably carried out as an evaporation step, also called the bleed solution, is recovered and returned to one or more of the previous process steps including the pulping step, and possibly also returned to the first leaching step, the second leaching step, and/or back to the crystallization step.
• the bleed solution obtained from the crystallization step is pretreated prior to returning it to previous process steps, e.g. by carbonation, using CO 2 to form a carbonate precipitate.
• the present invention relates to an arrangement for recovering lithium hydroxide from a fresh feed comprising a mineral raw material containing lithium or a raw material containing lithium carbonate, or a mixture of these raw materials, combined with a recycled solution and/or slurry.
• the arrangement com- prises
• the purification unit 32 is a membrane separation unit.
• the unit provides two streams, one being a purified solution, which can be carried directly to the crystallization unit 4, while the other is a recycle stream, which is suitable for carrying to the second leaching unit 3, for example via a recy- cle line 323 (see Fig. 6).
• the arrangement of the invention can include both an ion exchange unit 32a and a membrane sepa- ration unit 32b, and thus also a regeneration unit 33. Due to the presence of the membrane separation unit 32b, a recycle stream can be provided, carrying a recy- cle stream via line 323 to the second leaching unit 3.
• the arrangement includes two or more crystallization units 4, preferably being sequentially arranged.
• the crystallization unit(s) 4 can be preceded by a separate pre-concentration unit, preferably in the form of an evaporation unit, designed to provide a crystallization feed having an optimized concentration.
• the arrangement comprises a solid-liquid separation unit 41 connected to the crystallization unit 4 for separating the crystals obtained in the crystallization unit 4 from the spent slurry.
• one or more recycle lines 403,414,421,422 are arranged between the crystallizing unit 4, and/or the liquid section of the solid- liquid separation unit 41 , and an upstream unit.
• recycle lines may include recycle line 403 arranged between the crystallizing unit 4, or the liquid section of the solid-liquid separation unit 41, and the second leaching unit 3, recycle line 414 arranged between the crystallization unit 4, or the liquid section of the solid-liquid separation unit 41 , and an inlet of the crystallization unit 4, recycle line 421 arranged between the crystallization unit 4, or the liquid section of the solid-liquid separation unit 41, and the pulping unit 1, and recycle line 422 arranged between the crystallization unit 4, or the liquid sec- tion of the solid-liquid separation unit 41 , and the first leaching unit 2.
• Recycle line 403 is intended, among others, for carrying soluble alumin- ium back to the second leaching unit 3, after which it will form solid compounds that may be discarded.
• Recycle line 414 is intended for providing means of reusing, in the crystallization, as quickly as possible, the solution and/or slurry separated from the crystals obtained in the crystallization unit 4, i.e. the crystalliza- tion mother liquor, which is a saturated solution that contains lithium hydroxide.
• recycle lines 421 and 422 of which recycle line 421 is particularly preferred. These lines are intended for recy- cling and thus utilizing the lithium hydroxide that ends up in the mother liquor in the crystallization unit 4, while also preventing the build-up of other salts in the crystal- lization unit 4.
• the arrangement comprises a lithium precipitation unit 42 connected to the crystallization unit 4 or the solid-liquid sepa- ration unit 41 through a line 423.
• this precipitation unit 42 provides means for reusing the solution recovered from the crystallization unit 4, which is a concen- trated solution of a strong base, carrying a remarkable concentration of hydroxide ions.
• This concentration of hydroxide ions is caused by the fact that lithium hydrox- ide crystallization can only be achieved from a saturated solution of lithium hydrox- ide, which is typically >12 % solutions, depending on selected temperature.
• the lithium precipitation unit 42 includes a feed inlet 424 for feeding carbon dioxide, and optionally alkali metal carbonate, to the unit 42.
• recycle line 421 past the precipitation unit 42, since carbonation will take place also in the pulping unit 1, to which the recycle line 421 will lead.
• the lithium hydroxide solution is a concentrated solution of a strong base, it provides a highly suitable solution to be used to control the pH in the first leaching unit 2, which control is necessary in order to maintain suitable leaching conditions.
• this solution is brought into contact with the sodium carbonate solutions for example in the pulping step, some sparingly soluble lithium carbonate will simultaneously precipitate, as described below, by referring to reac- tion formula (3).
• This reaction provides lithium carbonate for further lithium hydrox- ide recovery and sodium hydroxide for pH control.
• one specific feature of the present invention is that it provides the means for supplying lithium carbonate already in line 102, leading to the first leaching unit 2, instead of forming the lithium carbonate only in the first leaching unit 2.
• the arrangement includes a purifica- tion unit 43 connected to the crystallization unit 4, and/or to the solid-liquid separa- tion unit 41 , wherein the solids obtained in the crystallization step can be purified.
• the purification unit 43 or a solid-liquid separation unit 44, connected to and downstream from the purification unit 43 is connected via a re- cycle line 432 to an upstream purification unit 32, or to a regeneration unit 33.
• a solid-liquid separation unit 44 connected to and downstream from the purification unit 43 is connected via a recycle line 444 to the crystallization unit 4.
• a solid-liquid separation unit 44 connected to and downstream from the purification unit 43 is connected via a recycle line 445 to the purification unit 43.
• the arrangement of the invention comprises a com- bined purification unit 41 ,43,44 for purifying the crystals obtained in the crystalliza- tion unit 4 from the spent solution, and separating the purified crystals from the spent washing solution.
• the recycle line 414 connects the combined unit 41 ,43,44 to the crystallization unit.
• the feed inlet 431 is connected to the combined purification unit 41,43,44.
• a recycle line 432 may connect the combined purification unit 41,43,44 to an upstream purification unit 32, or to a separate regeneration unit 33, and a recycle line 444 may connect the combined purification unit 41,43,44 to the crystallization unit 4.
• a recycle line 445 may connect a solids section of the combined purification unit 41,43,44 to the liq- uid section of the same combined unit 41 ,43,44.
• the arrangement includes a drying unit 45, connected to the crystallization unit 4, or connected to a solids section of a solid-liquid separation unit 41,44 downstream from the crystallization unit 4, wherein the obtained crystals of lithium hydroxide monohydrate can be dried.
• the drying unit 45 includes a product outlet 451 through which the final, battery grade, product can be recovered.
• the present invention also includes a method for recovering lithium hy- droxide from a fresh feed comprising mineral raw material containing lithium, or a raw material containing lithium carbonate, or a mixture of these, combined with a recycled solution and/or slurry containing lithium.
• the method of the invention comprises (by referring to the numbering used for the arrangement) pulping 1 the feed containing lithium in the presence of water and alkali metal carbonate for extracting the lithium from the feed and pro- ducing a first slurry containing lithium.
• the alkali metal carbonate is preferably selected from sodium and po- tassium carbonate, most suitably being at least partly composed of sodium car- bonate. Typically, the alkali metal carbonate is present in excess.
• the first lithium-containing slurry is leached 2 for a first time at an elevated tem- perature, for producing a second slurry containing lithium carbonate.
• the first leaching 2 of the first slurry containing lithium is typically per- formed in a suitable autoclave or series of autoclaves.
• the first leaching step is carried out at a temperature of 160 to 250°C, preferably at a temperature of 200 to 220°C.
• the first leaching step is preferably carried out at a pressure of 10 to 30bar, preferably 15 to 25bar. Suitable conditions for this step are typically achieved using high-pressure steam.
• At least a fraction of the water and alkali metal carbonate carried to the pulping step is obtained from a recycled aqueous solution containing said alkali metal carbonate, and optionally containing lithium carbonate.
• An optional solid-liquid separation step 21 can be carried out, wherein the solution can be separated from the solids after the first leaching step 2, and the solids carried to the second leaching step 3.
• the solution separated from the solids in the optional separation step 21 is returned to one or more of the preceding steps as a recycled solution.
• the lithium-containing phase (here typi- cally the solids, or the entire second slurry) is leached 3 for a second time using a hydroxide reagent, i.e. an alkaline earth metal hydroxide, preferably in an aqueous solution of the hydroxide reagent, in order to form a third slurry containing lithium hydroxide.
• a hydroxide reagent i.e. an alkaline earth metal hydroxide
• a separation of solids from the solution is carried out by solid-liquid separation 31. This separation 31 results in the formation of a solids fraction that may be discarded, and a solution containing lithium hydroxide.
• the alkali earth metal hydroxide used in the second leaching step 3 is preferably selected from calcium and barium hydroxide, more preferably being calcium hydroxide, optionally prepared by reaction of calcium oxide (CaO) in the aqueous solution.
• the alkali earth metal hydroxide used in the second leaching step 3 is mixed with water or an aqueous solution pri- or to addition to the second leaching step 3.
• the hydroxide reagent may, for ex- ample, be obtained from a separate slurrying step 30.
• crystals of lithium hydroxide monohy- drate are recovered by crystallising 4 from a lithium-containing solution, which has optionally been purified.
• the crystallizing is typically performed by heating the so- lution containing lithium to a temperature of approximately the boiling point of the solution, to evaporate the liquid, or by recrystallizing the monohydrate from a suit- able solvent.
• a pre-concentration can be carried out before the crystalliza- tion step, preferably as an evaporation.
• two or more crystallization units are used, preferably being sequentially arranged.
• the method of the invention enables production of pure lithium hydrox- ide monohydrate with excellent yield and purity in a continuous and simple pro- cess, typically providing battery grade lithium hydroxide monohydrate crystals, having a purity of 56.5% or higher of lithium hydroxide.
• the purified solution containing lithium hydrox- ide is mixed with one or more solutions recycled from subsequent steps of the method before being carried to the crystallization step 4, or these solutions can be fed separately to the crystallization 4.
• the crystallization step 4 is followed by a solid-liquid separa- tion step 41.
• the bleed solution obtained while crystallizing 4 the lithium hydroxide monohydrate can be recovered and is recycled to one or more of the previous process steps, including the pulping step 1, and optionally also the first leaching step, the second leaching step 3, and/or back to the crystallization step 4.
• the solution separated from the crystallization step is a saturated solu- tion that contains a remarkable concentration of lithium hydroxide, which should be recovered. Further, it is a concentrated solution of a strong base. Hence, it pro- vides a highly suitable solution to be used to control the pH in the first leaching unit 2. Due to the recycling streams carried to the pulping step 1 and the first leaching step 2, the main one being the stream carried to the pulping step via recycle line 211, this pH control is necessary. When this lithium hydroxide solution is brought into contact with the sodium carbonate solutions for example in the pulping step, some sparingly soluble lithium carbonate will simultaneously precipitate, as pre- sented in the following formula (3):
• This reaction provides lithium carbonate for further lithium hydroxide re- covery and sodium hydroxide for pH control.
• some impurities in the crystallization bleed solution e.g. alu- minium and silicon
• have a solubility that increases with increasing alkalinity e.g. caused by increasing lithium hydroxide concentration
• these impurities form sparingly soluble compounds (e.g. aluminium hy- droxide), and can be discarded with the solids in separation step 31.
• car- bonate ions can be recovered and utilized in this manner.
• At least a fraction of the solution separated from the crystallization step is carried to a lithium precipitation step 42, which pref- erably is carried out as a carbonation, wherein the solution is reacted with either carbon dioxide or an alkali metal carbonate, or both, preferably at least with car- bon dioxide, in order to form a lithium carbonate slurry, as presented in the follow- ing formula (4)
• Lithium hydroxide crystallization can only be achieved from a saturated solution of lithium hydroxide, which is typically >12 % solutions, depending on se- lected temperature.
• the solution recovered from the crystallization step pro- vides a concentrated solution of a strong base carrying a remarkable concentra- tion of hydroxide ions.
• the leaching steps are lower alkalinity environments.
• the first leaching step is carried out in a sodium carbonate milieu
• the second leaching step is carried out on a lower concen- tration lithium hydroxide solution; typically about 2-3,5 %.
• neutralization of the major part of the hydroxide ions is needed, and carbonization provides such a suitable neutralization.
• the solution and/or slurry returned from the crystallization step to the pulping step and optional- ly the first leaching step will thus contain some lithium hydroxide.
• This lithium hy- droxide will, however, typically be converted to the corresponding sparingly soluble carbonate in the pulping or first leaching step.
• the solids obtained in the crystalliza- tion step, containing crystals of lithium hydroxide monohydrate are purified using a washing solution before recovery as the product.
• the purified crystals of lithium hydroxide monohydrate are preferably separated from the washing solution, are dried, and thereafter recovered.
• the spent washing solution is, in turn, preferably separated from the pu- rified crystals of lithium hydroxide monohydrate, and is returned to the crystal washing step or to a step of regenerating a resin intended for being carried to the purification step, or to the crystallization step, or a fraction of the spent washing solution is returned to two or all three of these steps as a recycle solution.
• a 700g batch of calcined beta-spodumene material with a 3.0% Li con- tent, 178g of sodium carbonate and an additional 7g of solid lithium carbonate were mixed with water to form a slurry having a total volume of 2.8 liters.
• the slur- ry was added to a 1-gal autoclave and treated for two hours at 220°C. The auto- clave contents were allowed to cool and then the slurry was filtered.
• a 225.93g portion of the pressure leach cake and 25g of calcium oxide were slurried with 0.63I of deionized water and mixed to make up a slurry of total volume 0.75I.
• the slurry was treated for 1h at ambient temperature and finally solids and a liquid were separated by filtration, and the cake was washed with water.
• the contents of both the solids and the solution were analyzed.
• the solids residue contained 0.16% Li and the solution had a Li content of 6.7g/l.
• the contents of the solution are specified in the following Table 1.
• the lithium recovery/yield to the solution was excellent, at around 93%, whereby recycling of this solution to an early step of the process is highly benefi- cial.

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• 2019
  • 2019-11-15 KR KR1020227019197A patent/KR102901550B1/ko active Active
  • 2019-11-15 WO PCT/FI2019/050821 patent/WO2021094647A1/en not_active Ceased
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