Method for producing an adsorbent material and method for extracting lithium from saline solutions using the material
The present invention relates to the field of solid materials for the adsorption of lithium. In particular, the present invention relates to a new method for the preparation of a crystallized and shaped solid material, preferably in extruded form, of the formula (LiCl) x .2Al(OH) 3 ,nH 2 O, wherein n is between 0.01 and 10, x is between 0.4 and 1, wherein it comprises a step a) of precipitation of boehmite under specific temperature and pH conditions, a step of bringing into contact the precipitate obtained with LiCl, at least one acid extrusion-kneading shaping step, wherein the method also comprises a final hydrothermal treatment step, all of which makes it possible to increase the lithium adsorption capacity, the adsorption kinetics, as well as the lithium/boron selectivity of the materials obtained with respect to the materials of the prior art, when it is used in a lithium extraction method of saline solutions.
1. A method for preparing a crystalline solid material of formula (LiCl) x .2Al(OH) 3 ,nH 2 O, wherein n is between 0.01 and 10, x is between 0.4 and 1, and wherein the method comprises:
a) precipitating boehmite, in an aqueous medium, comprising bringing into contact at least one basic precursor and at least one acidic precursor, wherein at least one of the basic or acidic precursors comprises aluminum, in order to obtain a boehmite suspension, wherein the precipitation is carried out at a temperature of between 5 and 35° C., and the amount of the basic precursor is selected in order to obtain a pH of the end of precipitation in a reaction medium of between 7.5 and 9.5,
b) bringing into contact the precipitate obtained in a) with at least lithium chloride (LiCl) as lithium source to form a suspension,
c) filtering the suspension obtained in b) to obtain a paste,
d) drying the paste obtained at the end of c) at a temperature between 20 and 80° C.,
e) shaping the dried paste obtained in d) by acid extrusion-kneading, wherein the dried paste is kneaded in the presence of an amount of acid of between 0.05 and 5% by weight relative to dry material, wherein the dry material is the weight of the dried paste dried in an oven at 200° C., wherein the acid is an organic or inorganic acid, wherein the dried paste is then subjected to an extrusion, and the shaping the dried paste by acid extrusion-kneading is carried out in the absence of a binder, and
f) drying the shaped dried paste obtained at the end of e) at a temperature between 20 and 200° C.
2. The method according to claim 1 , wherein the basic precursor is sodium hydroxide (NaOH).
3. The method according to claim 1 , wherein the amount of the basic precursor is selected in order to obtain an end of precipitation pH of a) in the reaction medium of between 7.7 and 8.8.
4. The method according to claim 1 , wherein b) is carried out in the presence of a quantity of lithium chloride equivalent to a molar ratio of Li/Al between 0.3 and 4.
5. The method according to claim 1 , wherein the organic acid used in e) is a carboxylic acid or derivative thereof selected from the group consisting of carboxylic acid salts, alkaline salts and earth salts, alkali metal salts, ammonium salts, and acid anhydrides, while the inorganic acid used in e) is selected from the group consisting of nitric acid, phosphoric acid, sulfuric acid, hydrochloric acid, and mixtures thereof.
6. The method according to claim 5 wherein the acid is an organic acid selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, and mixtures thereof.
7. The method according to claim 6 , wherein e) is carried out in the presence of oxalic acid.
8. The method according to claim 7 , wherein the dried paste is kneaded in the presence of an amount of acid between 0.1 and 2.5% by weight relative to the dry material, wherein the dry material is the weight of the dried paste from e), dried in an oven at 200° C.
9. The method according to claim 1 , wherein the basic precursor is selected from the group consisting of sodium aluminate, potassium aluminate, ammonia, sodium hydroxide, and potassium hydroxide.
10. The method according to claim 1 , wherein the acidic precursor is aluminum chloride or hydrochloric acid.