Process for preparing an adsorbing material comprising a precipitating step of boehmite according to specific conditions and process for extracting lithium from saline solutions using this material

Abstract

The present invention relates to the field of solid materials for adsorption of lithium. In particular, the present invention relates to a novel method for preparing a crystallized and shaped solid material, preferably as extrudates, of formula LiX.sub.x.2Al(OH).sub.3, nH.sub.2O with n being comprised between 0.01 and 10, x being equal to 1 when X is an anion selected from among chloride, hydroxide and nitrate anions, and x being equal to 0.5 when X is an anion selected from among sulfate and carbonate anions, comprising a step a) for precipitation of boehmite under specific temperature and pH conditions, at least one shaping step, preferably by extrusion, said method also comprising a final hydrothermal treatment step, the whole giving the possibility of increasing the adsorption capacity for lithium as well as the adsorption kinetics of the materials obtained as compared with the materials of the prior art when the latter is used in a method for extracting the lithium from saline solutions.

Claims

1. A method for preparing a crystallized solid material of formula LiX.sub.x.2Al(OH).sub.3,nH2O with n being comprised between 0.01 and 10, x being equal to 1 when X is an anion selected from among chloride, hydroxide and nitrate anions, and x being equal to 0.5 when X is an anion selected from among sulfate and carbonate anions, said method comprising: a) precipitating boehmite in an aqueous medium, wherein the precipitation comprises contacting at least one basic precursor; and at least one acid precursor, wherein at least one of the basic or acid precursors comprises aluminium, thereby obtaining a suspension of boehmite, said precipitating being performed at a temperature comprised between 5 and 35 C., and wherein the amount of the basic precursor gives a pH at the end of precipitation in the reaction medium comprised between 7.5 and 9.5, b) washing and filtering the boehmite precipitate obtained in a), c) putting the precipitate obtained in b) in contact with at least one lithium source thereby obtaining a suspension, d) filtering the suspension obtained in c) thereby obtaining a slurry, e) drying the slurry obtained at the end of d) at a temperature comprised between 20 and 80 C., f) shaping said dried slurry, g) drying the shaped material obtained at the end of f) at a temperature comprised between 20 and 200 C., and h) hydrothermally treating the dry shaped material obtained at the end of g) at a temperature comprised between 50 and 200 C.

2. The method according to claim 1, wherein said basic precursor is selected from the group consisting of sodium aluminate, potassium aluminate, ammonia, sodium hydroxide, potassium hydroxide, and any mixture thereof.

3. The method according to claim 1, wherein said basic precursor is sodium hydroxide (NaOH).

4. The method according to claim 1, wherein said acid precursor is selected from the group consisting of aluminium sulfate, aluminium chloride, aluminium nitrate, sulfuric acid, hydrochloric acid, nitric acid, and any mixture thereof.

5. The method according to claim 1, wherein said acid precursor is aluminium trichloride (AlCl.sub.3).

6. The method according to claim 1, wherein said precipitating is performed at a temperature comprised between 10 and 25 C.

7. The method according to claim 1, wherein the amount of the basic precursor gives a pH at the end of precipitation in the reaction medium comprised between 7.7 and 8.8.

8. The method according to claim 1, wherein said lithium source is selected from the group consisting of lithium chloride (LiCl), lithium hydroxide (LiOH), lithium nitrate (LiNO.sub.3), lithium sulfate (Li.sub.2SO.sub.4) and lithium carbonate (Li.sub.2CO.sub.3), and any a mixture thereof.

9. The method according to claim 8, wherein said lithium source is lithium chloride (LiCl).

10. The method according to claim 1, wherein said shaping is achieved by extrusion.

11. The method according to claim 10, wherein said shaping is directly applied after the drying.

Description

DESCRIPTION OF THE FIGURES

(1) FIGS. 1, 3, 5 and 7 illustrate X-ray diffraction diagrams of the precipitated boehmites respectively obtained in Examples 1 and 2 according to the invention and the non-complaint Examples 3 and 4 of the invention.

(2) FIGS. 2, 4, 6 and 8 illustrate X-ray diffraction diagrams of solid materials of formula LiX.sub.x.2Al(OH).sub.3,nH.sub.2O with X=Cl, x=1 and n being comprised between 0.01 and 10 obtained as extrudates respectively in Examples 1 and 2 according to the invention and the non-compliant Examples 3 and 4 of the invention.

(3) FIG. 9 illustrates the saturation curve according to Example 5 produced from the extrudates obtained in Examples 1 to 4.

(4) The invention is illustrated by the following Examples which by no means have any limiting nature.

EXAMPLES

Example 1

According to the Invention

(5) A solid material of formula LiCl.2Al(OH).sub.3,nH.sub.2O with n being comprised between 0.01 and 1, is prepared according to a synthesis method according to the invention, wherein the shaping step is applied by direct extrusion, without any binder.

(6) 1/Precipitation of Boehmite AlOOH

(7) In a beaker cooled with an ice bath, a solution containing 326 ml of permuted water and 135.6 g of aluminium chloride hexahydrate (AlCl.sub.3) is prepared. Next with magnetic stirring, 67.5 g of sodium hydroxide (NaOH) are added for 30 minutes so as to adjust the pH. The pH attained at the end of the synthesis is 8. The temperature is maintained to 20 C. during the whole duration of the precipitation step. This cake is suspended in a 3 L beaker with 320 mL of water.

(8) A sample of the obtained precipitate is taken from the reaction medium. XRD (FIG. 1) of the precipitate shows that the precipite obtained in Example 1 is actually a boehmite precipitate. The boehmite precipitate obtained in Example 1 is not very crystallized.

(9) The size of the crystallites of the obtained boehmite is measured according to Sherrer's method:

(10) Size along [020]=0.60.1 (nm); Size along [120]=1.40.1 (nm)

(11) 2/Addition of Lithium Chloride LiCl.

(12) A solution is prepared containing 78.5 g of lithium chloride LiCl provided by Prolabo and 1,326 ml of water which is added to the repulped cake. This reaction medium is stirred and heated at 80 C. for 2 h.

(13) Filtration and then drying in an oven at 80 C. for 8 h follow the first 2 steps.

(14) The thereby prepared solid material is characterized by the formula LiCl.2Al(OH).sub.3,nH.sub.2O with n=0.25 according to a synthesis method compliant with the invention. The step for shaping the obtained slurry is directly carried out after the drying step, without any preliminary kneading step and in the absence of any binder. The obtained slurry is shaped by means of a piston extruder (MTS), equipped with a cylindrical die with a diameter of 1 mm.

(15) The extrudates obtained at the end of the shaping step are then dried in an oven at 40 C. for 12 h.

(16) The obtained extrudates are then subject to a hydrothermal treatment step in an autoclave comprising water. 10 g of extrudates are placed in a basket placed in a 500 ml autoclave. In the bottom of the autoclave 20 g of distilled water are placed. The extrudates are not in contact with the liquid at the bottom of the autoclave.

(17) The hydrothermal treatment is performed at a temperature of 100 C. for 6 h under an atmosphere saturated with water.

(18) Extrudates of the solid material of formula LiCl.2Al(OH).sub.3,nH.sub.2O with n=0.25 having good cohesion and a proper aspect are obtained. A phase LiCl.2Al(OH).sub.3,nH.sub.2O is detected on the X-ray diffraction diagram of the extrudates of the solid material of formula LiCl.2Al(OH).sub.3,nH.sub.2O with n=0.25 obtained in Example 1 (FIG. 2).

(19) The obtained extrudates are also characterized by the following measurements:

(20) The elementary analysis shows proper stoichiometry Li/Al/Cl corresponding to the composition of a structure LiCl.2Al(OH).sub.3,nH.sub.2O

(21) Al=21.2% by mass; Li=4.2% mass; Cl=19% by mass.

(22) The obtained extrudates have a specific surface area: S.sub.BET=3 m.sup.2/g.

(23) The extrudates obtained according to Example 1 visually show good cohesion, do not exhibit any or few cracks and both exhibit very good cohesion and very good mechanical strength when they are put into contact with a brine (a destruction percentage of less than 15% during the cohesion test) or with water (destruction percentage of less than 20% during the cohesion test).

Example 2

According to the Invention

(24) A solid material of formula LiCl.2Al(OH).sub.3,nH.sub.2O with n being comprised between 0.01 and 1 is prepared according to a synthesis method according to the invention, wherein the shaping step is applied by direct extrusion, without any binder.

(25) 1/Precipitation of Boehmite AlOOH

(26) In a beaker cooled with an ice bath, a solution containing 326 ml of permuted water and 135.6 g of aluminium chloride hexahydrate (AICl.sub.3) is prepared. Next with magnetic stirring, 67.5 g of sodium hydroxide (NaOH) are added for 30 minutes so as to adjust the pH. The pH attained at the end of the synthesis is 8.5. The temperature is maintained to 20 C. during the whole duration of the step. This cake is suspended in a 3 L beaker with 320 mL of water.

(27) A sample of the obtained precipitate is taken from the reaction medium. XRD (FIG. 3) of the precipitate shows that the precipitate obtained in Example 2 is actually a boehmite precipitate. The boehmite precipitate obtained in Example 2 is not very crystallized.

(28) The size of the crystallites of the obtained boehmite is measured according to Sherrer's method:

(29) Size along [020]=0.90.1 (nm); Size along [120]=1.60.2 (nm).

(30) 2/Addition of Lithium Chloride LiCl.

(31) A solution containing 78.5 g of lithium chloride LiCl provided by Prolabo is prepared and 1,326 ml of water which is added to the repulped cake. This reaction medium is stirred and heated to 80 C. for 2 h.

(32) Filtration and then drying in an oven at 80 C. for 8 h follow the first 2 steps.

(33) The thereby prepared solid material is characterized by the formula LiCl.2Al(OH).sub.3,nH.sub.2O with n=0.25 according to a synthesis method according to the invention. The step for shaping the obtained slurry is directly carried out after the drying step, without any preliminary kneading step and in the absence of any binder.

(34) The obtained slurry is shaped by means of a piston extruder (MTS), equipped with a cylindrical die with a diameter of 1 mm.

(35) The extrudates obtained at the end of the shaping step are then dried in an oven at 40 C. for 12 h.

(36) The obtained extrudates are then subject to a hydrothermal treatment step in an autoclave comprising water. 10 g of extrudates are placed in a basket placed in a 500 ml autoclave. 20 g of distilled water are placed in the bottom of the autoclave. The extrudates are not in contact with the liquid at the bottom of the autoclave.

(37) The hydrothermal treatment is performed at a temperature of 100 C. for 6 h under an atmosphere saturated with water.

(38) Extrudates of the solid material of formula LiCl.2Al(OH).sub.3,nH.sub.2O with n=0.25 having good cohesion and a proper aspect are obtained. A phase LiCl.2Al(OH).sub.3,nH.sub.2O is detected on the X-ray diffraction diagram of the extrudates of the solid material of formula LiCl.2Al(OH).sub.3,nH.sub.2O with n=0.25 of FIG. 4.

(39) The obtained extrudates are also characterized by the following measurements:

(40) Elementary analysis shows good stoichiometry Li/Al/CI corresponding to the composition of a structure LiCl.2Al(OH).sub.3,nH.sub.2O

(41) Al=20.00% by mass; Li=4.03% by mass; Cl=20.5% by mass, C=5.87% by mass.

(42) The obtained extrudates have a specific surface area: S.sub.BET=3 m.sup.2/g.

(43) The extrudates obtained according to Example 2 visually show good cohesion, have no or very few cracks and both exhibit very good cohesion and a very good mechanical strength when the latter are put into contact with brine (destruction percentage of less than 15% during the cohesion test) or with water (destruction percentage of less than 20% during the cohesion test).

Example 3

Comparative

(44) A solid material of formula LiCl.2Al(OH).sub.3,nH.sub.2O with n being comprised between 0.01 and 1, is prepared according to a synthesis method not compliant with the invention, in that the pH at the end of the precipitation of the step for synthesis of boehmite is carried out at a pH greater than 9.5.

(45) 1/Precipitation of Boehmite AlOOH

(46) In a beaker cooled with an ice bath, a solution containing 326 ml of permuted water and 135.6 g of aluminium chloride hexahydrate (AlCl.sub.3) is prepared. Next with magnetic stirring, 67.5 g of sodium hydroxide (NaOH) are added for 30 minutes so as to adjust the pH. The pH attained at the end of the synthesis is 10. The temperature is maintained to 20 C. for the whole duration of the step. This cake is suspended in a 3 L beaker with 320 mL of water.

(47) A sample of the obtained precipitate is taken from the reaction medium. The XRD (FIG. 5) of the precipitate shows that the obtained precipitate in Example 3 is actually a boehmite precipitate.

(48) The size of the crystallites of the obtained boehmite is measured according to Sherrer's method: Size along [020]=2.12 (nm); Size along [120]=2.83 (nm)

(49) 2/Addition of Lithium Chloride LiCl.

(50) A solution containing 78.5 g of lithium chloride LiCl provided by Prolabo and 1,326 ml of water is prepared, which is added to the repulped cake. This reaction medium is stirred and heated to 80 C. for 2 h.

(51) Filtration and then drying in an oven at 80 C. for 8 h follow the first 2 steps.

(52) The step for shaping the obtained slurry is directly carried out after the drying step, without any preliminary kneading step and in the absence of any binder.

(53) The obtained slurry is shaped by means of a piston extruder (MTS), equipped with a cylindrical die with a diameter of 1 mm.

(54) The extrudates obtained at the end of the shaping step are then dried in an oven at 40 C. for 12 h.

(55) The obtained extrudates are then subject to a hydrothermal treatment step in an autoclave comprising water. 10 g of extrudates are placed in a basket placed in a 500 ml autoclave. 20 g of distilled water are placed in the bottom of the autoclave. The extrudates are not in contact with the liquid at the bottom of the autoclave.

(56) The hydrothermal treatment is performed at a temperature of 100 C. for 6 h under an atmosphere saturated with water.

(57) Extrudates of the solid material of formula LiCl.2Al(OH).sub.3,nH.sub.2O with n=0.25 having good cohesion and a proper aspect are obtained. A phase LiCl.2Al(OH).sub.3,nH.sub.2O is detected on the X-ray diffraction diagram of the extrudates of the solid material of formula LiCl.2Al(OH).sub.3,nH.sub.2O with n=0.25 of FIG. 6.

(58) The obtained extrudates are also characterized by the following measurements:

(59) The elementary analysis shows good stoichiometry Li/Al/Cl corresponding to the composition of a structure LiCl.2Al(OH).sub.3,nH.sub.2O

(60) Al=20.00% by mass; Li=4.03% by mass; Cl=20.5% by mass, C=5.87% by mass.

(61) The obtained extrudates have a specific surface area: S.sub.BET=3 m.sup.2/g.

(62) The extrudates obtained according to Example 3 visually show good cohesion, have no or few cracks and have both very good cohesion and very good mechanical strength when the latter are put into contact with brine (destruction percentage of less than 15% during the cohesion test) or with water (destruction percentage of less than 20% during the cohesion test).

Example 4

Comparative

(63) A solid material of formula LiCl.2Al(OH).sub.3,nH.sub.2O with n being comprised between 0.01 and 1, according to a synthesis method not compliant with the invention, in that the temperature of the step for precipitation of boehmite is achieved at a temperature of 40 C.

(64) 1/Precipitation of Boehmite AlOOH

(65) In a beaker cooled by an ice bath, a solution containing 326 ml of permuted water and 135.6 g of aluminium chloride hexahydrate (AlCl.sub.3) is prepared. Next, with magnetic stirring, 67.5 g of sodium hydroxide (NaOH) are added for 30 minutes so as to adjust the pH. The pH attained at the end of the synthesis is 8. The temperature is maintained to 40 C. during the whole duration of the step. This cake is suspended in a 3 L beaker with 320 mL of water.

(66) A sample of the obtained precipitate is taken from the reaction medium. The XRD (FIG. 7) of the precipitate shows that the obtained precipitate in Example 4 is actually a boehmite precipitate.

(67) The size of the crystallites of the obtained boehmite is measured according to Sherrer's method: Size along [020]=1.93 (nm); Size along [120]=2.62 (nm)

(68) 2/Addition of Lithium Chloride LiCl.

(69) A solution containing 78.5 g of lithium chloride LiCl provided by Prolabo and 1,326 ml of water is prepared, which is added to the repulped cake. This reaction medium is stirred and heated to 80 C. for 2 h.

(70) A filtration and then drying in an oven at 80 C. for 8 h follow the first 2 steps.

(71) The step for shaping the obtained slurry is directly carried out after the drying step, without any preliminary kneading step and in the absence of any binder.

(72) The obtained slurry is shaped by means of a piston extruder (MTS), equipped with a cylindrical die with a diameter of 1 mm.

(73) The extrudates obtained at the end of the shaping step are then dried in an oven at 40 C. for 12 h.

(74) The obtained extrudates are then subject to a hydrothermal treatment step in an autoclave comprising water. 10 g of extrudates are placed in a basket placed in a 500 ml autoclave. 20 g of distilled water are placed in the bottom of the autoclave. The extrudates are not in contact with the liquid at the bottom of the autoclave.

(75) The hydrothermal treatment is performed at a temperature of 100 C. for 6 h under an atmosphere saturated with water.

(76) Extrudates of the solid material of formula LiCl.2Al(OH).sub.3,nH.sub.2O with n=0.25 having good cohesion and a proper aspect are obtained. A phase LiCl.2Al(OH).sub.3,nH.sub.2O is detected on the X-ray diffraction diagram of the extrudates of the solid material of formula LiCl.2Al(OH).sub.3,nH.sub.2O with n=0.25 of FIG. 8.

(77) The obtained extrudates are also characterized by the following measurements:

(78) Elementary analysis shows good stoichiometry Li/Al/Cl corresponding to the composition of a structure LiCl.2Al(OH).sub.3,nH.sub.2O

(79) Al=20.00% by mass; Li=4.03% by mass; Cl=20.51% by mass.

(80) The obtained extrudates have a specific surface area: S.sub.BET=2 m.sup.2/g.

(81) The extrudates obtained according to Example 4 visually show good cohesion, have no or few cracks and both have very good cohesion and very good mechanical strength when the latter are put into contact with a brine (destruction percentage of less than 15% during the cohesion test) or with water (destruction percentage of less than 20% during the cohesion test).

Example 5

Test of the Adsorption Capacity and of the Adsorption Kinetics

(82) The adsorption kinetics of lithium by the extrudates and their adsorption capacity is tested by producing a piercing curve also called a leak curve or saturation curve in a column. A saturation curve is produced for each of the extrudates obtained in Examples 1 to 4: 15 g of solid are placed in a column 10 column volumes of a saline solution of lithium chloride (LiCl) at 0.02 mol/L cross the column in a closed circuit until a stable lithium concentration is attained in solution A natural solution containing about 0.06 mol/L of lithium crosses the column by flowing upwards, at a rate of 6 BV/h, i.e. six times the volume occupied by the bed of the extrudates within one hour. Lithium concentration is measured at the outlet of the column depending on the solution volume which has passed.

(83) FIG. 9 illustrates the saturation curves obtained for each of the extrudates obtained in the Examples according to the invention 1 and 2 and those not compliant with the invention 3 and 4.

(84) The extrudates obtained according to Examples 1 and 2 according to the invention are compared with those obtained in the Examples 3 and 4 obtained according to preparation methods non-compliant with the invention. The extrudates of Examples 1 and 2 obtained according to the invention exhibit a lithium leak occurring at greater brine volumes having cast. Their adsorption capacities of lithium are respectively 5.8 and 6.2 mg(Li)/g (dry solid), to be compared with 1.7 and 4.3 mg(Li)/g (dry solid) for the solids obtained according to Examples 3 and 4, according to preparation methods non-compliant with the invention.