Process for preparing an adsorbent material and process for extracting lithium using said material

Abstract

The present invention relates to the field of solid materials for the adsorption of lithium. In particular, the present invention relates to a novel process for preparing a solid crystalline material formed preferably in extrudate form, of formula (LiCl).sub.x.2Al(OH).sub.3,nH.sub.2O with n being between 0.01 and 10, x being between 0.4 and 1, comprising a step a) to precipitate boehmite under specific conditions of temperature and pH, a step to place the precipitate obtained in contact with a specific quantity of LiCl, at least one forming step preferably via extrusion, said process also comprising a final hydrothermal treatment step, all allowing an increase in lithium adsorption capacity and in the adsorption kinetics of the materials obtained compared to prior art materials, when used in a process to extract lithium from saline solutions.

Claims

1. A process for preparing a solid crystalline material of formula (LiCl).sub.x.2Al(OH).sub.3.nH.sub.2O, wherein n is between 0.01 and 10, and x is between 0.4 and 0.6, said process comprising: a) precipitating boehmite, in an aqueous medium, comprising the contacting of at least one base precursor with at least one acid precursor, wherein at least one of the base or acid precursors comprises aluminium, to obtain a suspension of boehmite, said precipitating being conducted at a temperature of between 5 and 35° C., and the amount of base precursor being selected so as to obtain an end-precipitation pH of between 7.5 and 9.5 in the reaction medium; b) washing and filtering the precipitate of boehmite obtained in a); c) placing the precipitate obtained in b) in contact with a quantity of lithium chloride equivalent to a Li/AI molar ratio of between 0.3 and 0.5; d) filtering the suspension obtained in c) to obtain a paste; e) drying the paste obtained in d) at a temperature of between 20° C. and 80° C.; f) shaping said dried paste; and g) drying the shaped dried paste obtained in f) at a temperature of between 20° C. and 200° C.

2. The process according to claim 1, wherein the base precursor is sodium hydroxide (NaOH).

3. The process according to claim 1, wherein said precipitating is conducted at a temperature of between 10 and 25° C.

4. The process according to claim 1, wherein the amount of base precursor is selected so as to obtain an end-precipitation pH in the reaction medium of between 7.7 and 8.8.

5. The process according to claim 1, wherein c) is conducted for a time of between 15 minutes and 5 hours.

6. The process according to claim 1, wherein f) is implemented via extrusion.

7. The process according to claim 6, wherein f) is implemented directly after e).

8. The process according to claim 6, wherein f) is implemented via base knead-extrusion wherein said dried paste derived in e) is kneaded in the presence of an amount of base of between 0.5 and 3 weight % relative to the dry matter, the dry matter being the weight of said paste derived from e), said base being selected from the group consisting of inorganic bases and organic bases in solution, and wherein said paste is then subjected to an extrusion.

9. The process according to claim 1, wherein said base precursor is selected from the group consisting of sodium aluminate, potassium aluminate, ammonia, sodium hydroxide, potassium hydroxide, and any mixtures thereof.

10. The process according to claim 1, wherein said acid precursor is selected from the group consisting of aluminium chloride, hydrochloric acid, and any mixtures thereof.

Description

DESCRIPTION OF THE FIGURES

(1) FIGS. 1 and 3 give X-ray diffraction diagrams of the precipitated boehmites obtained in Examples 1 to 3 for FIG. 1 and in Example 4 for FIG. 3 respectively.

(2) FIGS. 2 and 4 give X-ray diffraction diagrams of the solid materials obtained in the form of extrudates in Examples 1 to 3 for FIG. 2 and in Example 4 for FIG. 4 respectively.

(3) FIG. 5 illustrates the saturation curve of Example 5 determined with extrudates obtained in Examples 1 to 4.

(4) The invention is illustrated by the following examples which are in no way limiting.

EXAMPLES

Example 1: (of the Invention)

(5) A solid material was prepared of formula (LiCl).sub.x.2Al(OH).sub.3,nH.sub.2O with n being between 0.01 and 1 and x=0.6, with a synthesis process conforming to the invention, wherein the contacting step c) was performed with a Li/Al ratio of 0.5, and the forming step was carried out via direct extrusion without a binder.

(6) 1/Precipitation of Boehmite AlOOH

(7) In a beaker cooled over an ice bath, a solution was prepared containing 326 ml of deionized water and 135.6 g of aluminium chloride hexahydrate (AlCl.sub.3,6H.sub.2O). Under magnetic stirring 67.5 g of sodium hydroxide (NaOH) were added over 30 minutes to adjust the pH. The pH reached on completion of synthesis was 8. The temperature was held at 20° C. throughout the entire duration of the precipitation step. This cake was placed in suspension in a 3 L beaker with 320 mL of water.

(8) A sample of the precipitate obtained was taken from the reaction medium. The XRD (FIG. 1) of the precipitate shows that the precipitate obtained in Example 1 is indeed a boehmite precipitate. The boehmite precipitate obtained in Example 1 is scarcely crystallized. The size of the crystallites of the boehmite obtained was measured using the Scherrer method:

(9) Size along [020]=0.6±0.1 (nm); Size along [120]=1.4±0.1 (nm)

(10) 2/Addition of Lithium Chloride LiCl.

(11) A solution was prepared containing 11.9 g of lithium chloride LiCl supplied by Prolabo, corresponding to a Li/Al molar ratio of 0.5, with 1326 ml of water, and added to the repulped cake of preceding step 1. This reaction medium was left under agitation and heated to 80° C. for 2 h.

(12) Filtering and drying in an oven, at 80° C. for 8 h, followed after the first 2 steps.

(13) The solid material thus prepared was characterized by the formula (LiCl)x.2Al(OH).sub.3,nH.sub.2O with n=0.25 and x=0.6, using a synthesis process conforming to the invention. The forming step of the paste obtained was carried out directly after the drying step with no prior kneading step and no binder. The paste obtained was formed using a piston extruder (MTS) fitted with a cylindrical die 1 mm in diameter.

(14) The extrudates were dried in an oven at 40° C. for 12 h.

(15) The extrudates obtained were subjected to a hydrothermal treatment step in an autoclave containing water. 10 g of extrudates were placed in a basket positioned in a 500 ml autoclave. 20 g of distilled water were placed in the bottom of the autoclave. The extrudates were not in contact with the liquid at the bottom of the autoclave.

(16) Hydrothermal treatment was conducted at a temperature of 100° C. for 6 h in a water-saturated atmosphere.

(17) The extrudates of the solid material obtained showed good cohesion and were of good appearance. According to the X-ray diffractogram a LiCl.2Al(OH).sub.3,nH.sub.2O phase was detected (FIG. 2).

(18) The extrudates obtained were also characterized by the following measurements:

(19) Elementary analysis showed good Li/Al/Cl stoichiometry corresponding to the composition of a (LiCl).sub.0.6.2Al(OH).sub.3,nH.sub.2O structure.

(20) Al=24.8 weight %; Li=1.9 weight %; Cl=9.8 weight %.

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

(22) The extrudates obtained in Example 1 visually exhibited good cohesion, had few or no cracks and showed very good cohesion and very good mechanical strength when placed in contact with brine (percent destruction less than 15% at the cohesion test) or water (percent destruction less than 20% at the cohesion test).

Example 2: (of the Invention)

(23) A solid material was prepared of formula (LiCl)x.2Al(OH).sub.3,nH.sub.2O with n being between 0.01 and 1 and x=0.6, with the synthesis process conforming to the invention, wherein the contacting step was conducted with a Li/Al molar ratio of 0.5 and the forming step carried out by basic knead-extrusion.

(24) 1/Precipitation of Boehmite AlOOH

(25) In a beaker cooled over an ice bath, a solution was prepared containing 326 ml of deionized water and 135.6 g of aluminium chloride hexahydrate (AlCl.sub.3). Under magnetic stirring, 67.5 g of sodium hydroxide (NaOH) were added over 30 minutes to adjust the pH. The pH reached on completion of synthesis was 8. The temperature was held at 20° C. throughout the duration of the precipitation step. The suspension obtained was filtered and washed with water. The cake was placed in suspension in a 3 L beaker with 320 mL of water.

(26) A sample of the precipitate obtained was taken from the reaction medium. The XRD of the precipitate was identical to the XRD obtained in Example 1 (cf. FIG. 1) showing that the precipitate obtained in Example 2 was indeed a boehmite precipitate. The boehmite precipitate obtained in Example 2 was scarcely crystallized.

(27) The size of the crystallites of the boehmite obtained was measured using the Scherrer method:

(28) Size along [020]=0.6±0.1 (nm); Size along [120]=1.4±0.1 (nm)

(29) 2/Addition of Lithium Chloride LiCl.

(30) A solution was prepared containing 11.9 g of lithium chloride LiCl supplied by Prolabo, corresponding to a Li/Al ratio of 0.5, with 1326 ml of water, and added to the repulped cake of preceding step 1. This reaction medium was left under agitation and heated to 80° C. for 2 h.

(31) Filtering then drying in an oven, at 80° C. for 8 h, followed after the first 2 steps.

(32) 3/Knead-Extrusion

(33) The forming step was carried out by kneading then extrusion. For the kneading step, 35.5 g of the paste obtained above were placed in a kneader of Brabender type (80 ml capacity) with 1.39 g of 20.18 weight % ammonia solution, corresponding to 1% by weight of base (NH.sub.4OH) relative to the dry matter, the dry matter being the weight of said paste after the previous drying, dried in an oven at 200° C. for 6 h. The ammonia solution was mixed with 16 g of demineralized water and added over 2 minutes under kneading at 50 rpm. Additional water of about 2.7 g was added to obtain a homogeneous, extrudable, cohesive paste. Kneading was continued at the same speed for 30 minutes after completion of the addition of ammonia and water.

(34) The paste obtained was formed using a piston extruder (MTS) fitted with a cylindrical die 1 mm in diameter.

(35) The extrudates obtained were subjected to a hydrothermal treatment step in an autoclave containing water. 10 g of extrudates were placed in a basket positioned in a 500 ml autoclave. 20 g of distilled water were placed in the bottom of the autoclave. The extrudates were not in contact with the liquid at the bottom of the autoclave.

(36) Hydrothermal treatment was carried out at a temperature of 100° C. for 6 h in a water-saturated atmosphere.

(37) The extrudates of the solid material obtained in Example 2 showed good cohesion and good appearance. The X-ray diffractogram detected a LiCl.2Al(OH).sub.3,nH.sub.2O phase (FIG. 2).

(38) The XRD of the final material was identical to the XRD of the material obtained in Example 1 (cf. FIG. 2).

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

(40) Elementary analysis showed good Li/Al/Cl stoichiometry corresponding to the composition of a (LiCl).sub.0.6.2Al(OH).sub.3,nH.sub.2O structure.

(41) Al=24.8 weight %; Li=1.9 weight %; Cl=9.8 weight %.

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

(43) The extrudates obtained in Example 2 visually displayed good cohesion, had few or no cracks and showed very good cohesion and very good mechanical strength when placed in contact with brine (percent destruction less than 15% at the cohesion test) or water (percent destruction less than 20% at the cohesion test).

Example 3: (Comparative)

(44) A solid material was prepared of formula (LiCl).sub.x.2Al(OH).sub.3,nH.sub.2O with n between 0.01 and 1 and x=1, with a synthesis process not conforming to the invention in that the contacting step c) was performed with a Li/Al ratio of 3.3. The forming step was implemented by basic knead-extrusion.

(45) 1/Precipitation of Boehmite AlOOH

(46) In a beaker cooled over an ice bath, a solution was prepared containing 326 ml of deionized water and 135.6 g of aluminium chloride hexahydrate (AlCl.sub.3). Under magnetic stirring, 67.5 g of sodium hydroxide (NaOH) were added over 30 minutes to adjust the pH. The pH reached on completion of synthesis was 8. The temperature was held at 20° C. throughout the entire duration of the precipitation step. The suspension obtained was filtered and washed with water. The cake was placed in suspension in a 3 L beaker with 320 mL of water.

(47) A sample of the precipitate obtained was taken from the reaction medium. The XRD of the precipitate was identical to the XRD obtained in Example 1 (cf. FIG. 1) and showed that the precipitate obtained in Example 3 was indeed a precipitate of boehmite. The boehmite precipitate obtained in Example 3 was scarcely crystallized.

(48) The size of the crystallites of the boehmite obtained was measured with the Scherrer method:

(49) Size along [020]=0.6±0.1 (nm); Size along [120]=1.4±0.1 (nm)

(50) 2/Addition of Lithium Chloride LiCl.

(51) A solution was prepared containing 78.5 g of lithium chloride LiCl supplied by Prolabo, corresponding to a Li/Al ratio of 3.3, and 1326 ml of water, and was added to the repulped cake of preceding step 1. This reaction medium was left under agitation and heated to 80° C. for 2 h.

(52) Filtration then drying in an oven, at 80° C. for 8 h, followed after the first 2 steps.

(53) 3/Knead-Extrusion

(54) The forming step was implemented by kneading then extrusion. For the kneading step, 35.5 g of the paste obtained above were placed in a kneader of Brabender type (80 ml capacity) with 1.39 g of 20.18 weight % ammonia solution corresponding to 1% by weight of base (NH.sub.4OH) relative to the dry matter, the dry matter being the weight of said paste after the previous drying, dried in an oven at 200° C. for 6 h. The ammonia solution was mixed with 16 g of demineralized water and added over 2 minutes under kneading at 50 rpm. Additional water of about 2.7 g was added to obtain a homogenous, extrudable, cohesive paste. Kneading was continued at the same speed for 30 minutes after completion of the addition of ammonia and water.

(55) The paste obtained was formed using a piston extruder (MTS), fitted with a cylindrical die 1 mm in diameter.

(56) The extrudates obtained were subjected to hydrothermal treatment in an autoclave containing water. 10 g of extrudates were placed in a basket positioned in a 500 ml autoclave. 20 g of distilled water were placed in the bottom of the autoclave. The extrudates were not in contact with the liquid at the bottom of the autoclave.

(57) Hydrothermal treatment was conducted at a temperature of 100° C. for 6 h in a water-saturated atmosphere.

(58) Extrudates of the solid material of formula (LiCl).sub.x.2Al(OH).sub.3,nH.sub.2O with n=0.25 and x=1 showing good cohesion and good appearance were obtained. A LiCl.2Al(OH).sub.3,nH.sub.2O phase was detected in the X-ray diffractogram of the extrudates of solid material of formula (LiCl).sub.x.2Al(OH).sub.3,nH.sub.2O with n=0.25 and x=1 obtained in Example 3. Th XRD of the final material was identical to the XRD of the material obtained in Example 1 (cf. FIG. 2).

(59) The extrudates obtained were also characterized by the following measurements:

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

(61) Al=23 weight %; Li=3 weight %; Cl=15.1 weight %.

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

(63) The extrudates obtained in Example 3 visually exhibited good cohesion, had few or no cracks and showed very good cohesion and very good mechanical strength when placed in contact with brine (percent destruction less than 15% at the cohesion test) or water (percent destruction less than 20% at the cohesion test).

Example 4: Comparative

(64) A solid material was prepared of formula (LiCl).sub.x.2Al(OH).sub.3,nH.sub.2O with n being between 0.01 and 1 and x=1 with a synthesis process not conforming to the invention in that the boehmite precipitation step was conducted at pH=10. The contacting step c) was performed with a Li/Al ratio=0.5.

(65) 1/Precipitation of Boehmite AlOOH

(66) In a beaker cooled over an ice bath, a solution was prepared containing 326 ml of deionized water and 135.6 g of aluminium chloride hexahydrate (AlCl.sub.3). Under magnetic stirring, 67.5 g of sodium hydroxide (NaOH) were added over 30 minutes to adjust the pH. The pH reached on completion of synthesis was 10. The temperature was held at 20° C. throughout the entire duration of the precipitation step. This cake was placed in suspension in a 3 L beaker with 320 mL of water.

(67) A sample of the precipitate obtained was taken from the reaction medium. The XRD (FIG. 3) of the precipitate showed that the precipitate obtained in Example 4 was indeed a precipitate of boehmite that was extremely well crystallized.

(68) The size of the crystallites of the boehmite obtained was measured with the Scherrer method: Size along [020]=2.1±2 (nm); Size along [120]=2.8±3 (nm)

(69) 2/Addition of Lithium Chloride LiCl.

(70) A solution was prepared containing 11.9 g of lithium chloride LiCl supplied by Prolabo, corresponding to a Li/Al ratio of 0.5, with 1326 ml of water, and added to the repulped cake of preceding step 1. This reaction medium was left under agitation and heated to 80° C. for 2 h.

(71) Filtration then drying in an oven, at 80° C. for 8 h, followed after the 2 first steps.

(72) The solid material thus prepared was characterized by the formula (LiCl).sub.x.2Al(OH).sub.3,nH.sub.2O with n=0.25 and x=0.6 with a synthesis process conforming to the invention. The forming step of the paste obtained was implemented directly after the drying step, with no prior kneading step and no binder. The paste obtained was formed in a piston extruder (MTS), fitted with a cylindrical die 1 mm in diameter.

(73) The extrudates were prepared as in Example 4 up until the drying step in an oven at 40° C. for 12 h.

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

(75) The hydrothermal treatment was conducted at a temperature of 100° C. for 6 h in a water-saturated atmosphere.

(76) Extrudates of the solid material of formula (LiCl).sub.x.2Al(OH).sub.3,nH.sub.2O with n=0.25 and x=0.6 having good cohesion and good appearance were obtained. A (LiCl).sub.x.2Al(OH).sub.3,nH.sub.2O phase was detected in the X-ray diffractogram of the extrudates of the solid material of formula (LiCl).sub.x.2Al(OH).sub.3,nH.sub.2O with n=0.25 and x=1 obtained in Example 1 (FIG. 4).

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

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

(79) Al=24.8 weight %; Li=1.9 weight %; Cl=9.8 weight %.

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

(81) The extrudates obtained in Example 4 visually displayed good cohesion, had few or no cracks, and showed very good cohesion and very good mechanical strength when placed in contact with brine (percent destruction less than 15% at the cohesion test) or water (percent destruction less than 20% at the cohesion test).

Example 5: Test on Adsorption Capacity and Adsorption Kinetics

(82) The adsorption kinetics of lithium by the extrudates and their adsorption capacity were tested by determining a breakthrough curve, also called a leak curve or saturation curve, in a column. A saturation curve was determined for each of the solid extrudates obtained in Examples 1 to 4: 15 g of solids (extrudates) were placed in a column; 10 bed volumes of a saline solution of lithium chloride (LiCl) at 0.02 mol/L was passed through the column in a closed circuit until a stable concentration of lithium in solution was obtained; A natural solution containing about 0.06 mol/L of lithium was passed through the column in upflow direction at a flow rate of 6 BV/h, i.e. six times the volume occupied by the bed of extrudates in one hour; The lithium concentration was measured at the outlet of the column as a function of the volume of solution that was passed.

(83) FIG. 5 gives the saturation curves obtained for each of the extrudates obtained in Examples 1 and 2 conforming to the invention, and 3 and 4 not conforming to the invention.

(84) The results obtained are summarized in Table 1.

(85) TABLE-US-00001 TABLE 1 end- Li Capacity precipitation added mg(Li)/ Examples x knead pH (Li/Al) g(dry solid) 1 0.6 direct 8 0.5 6.6 2 0.6 basic 8 0.5 6.6 3 1 basic 8 3.3 5.8 4 0.6 basic 10 0.5 4.3

(86) The extrudates obtained in Examples 1 and 2 of the invention were compared with those obtained in Examples 3 and 4 for which the preparation processes did not conform to the invention. The extrudates in Examples 1 and 2 obtained with the invention show the onset of lithium leakage at higher volumes of passed brine. Their lithium adsorption capacities are respectively 6.6 and 6.6 mg (Li)/g (dry solid), compared to 5.8 and 4.3 mg (Li)/g (dry solid) respectively for the solids obtained in Examples 3 and 4 using preparation processes not conforming to the invention.