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

A method for preparing a crystallized solid material of formula LiXx.2Al(OH)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 at least the following steps:

• 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 step a) 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) awashing and filtering the boehmite precipitate obtained in step a),
• c) a putting the precipitate obtained in step b) in contact with at least one lithium source,
• d) a filtering the suspension obtained in step c) thereby obtaining a slurry,
• e) a drying the slurry obtained at the end of step d) at a temperature comprised between 20 and 80° C.,
• f) a shaping said dried slurry,
• g) a drying the shaped material obtained at the end of step f) at a temperature comprised between 20 and 200° C.,
• h) a hydrothermally treating the dry shaped material obtained at the end of step g) at a temperature comprised between 50 and 200° C.