Method for preparing an adsorbent material comprising a step of basic mixing, and method for extracting lithium from saline solutions using said material

Method for preparing a crystallized solid material of formula Lix.2Al(OH)3,nH2O, wherein n is between 0.01 and 10, and x is equal to 1 when X is an anion selected from the group consisting of chloride, hydroxide and nitrate anions, and x is 0.5 when X is an anion selected from the group consisting of sulfate and carbonate anions, wherein the method comprises:

• a) precipitating boehmite, in an aqueous medium, of at least one basic precursor selected from the group consisting of among sodium aluminate, potassium aluminate, aqueous ammonia, sodium hydroxide and potassium hydroxide;
• and at least one acidic precursor selected from the group consisting of aluminum sulphate, aluminum chloride, aluminum nitrate, sulfuric acid, hydrochloric acid, and nitric acid, wherein at least one of one of the basic or acidic precursors comprises aluminum, to obtain a boehmite suspension, wherein a) is operated at a temperature of between 5 and 35° C., and wherein the amount of the basic precursor is chosen in order to obtain a pH of end of precipitation in the reaction medium of between 7.5 and 9.5,
• b) filtering and washing the boehmite precipitate obtained in a),
• c) contacting the precipitate obtained in b) with at least one lithium source,
• d) filtering the suspension obtained in c) to obtain a paste,
• e) drying the paste obtained at the end of d) at a temperature of between 20 and 80° C.,
• f) shaping the basic extrusion-mixed dough in which the dried dough resulting from e) is mixed in the presence of an amount of a base between 0.5 and 3% by weight relative to the dry matter, wherein the base is selected from the group consisting of inorganic bases and organic bases in solution, and in which the dough is then subjected to an extrusion, and
• g) hydrothermally treating the dried shaped material obtained at the end of step f), at a temperature of between 50 and 200° C.,
• thereby providing a crystallized solid material of formula LiXx2Al(OH)3,nH2O, wherein n is between 0.01 and 10, and x is equal to 1 when X is an anion selected from the group consisting of chloride, hydroxide and nitrate anions, and x is 0.5 when X is an anion selected from the group consisting of sulfate and carbonate anions.