Process for preparing ultralow-sodium boehmite by hydrothermal method and ultralow-sodium boehmite

The embodiment of the invention relates to the technical field of boehmite production, in particular to a process for preparing ultralow-sodium boehmite by a hydrothermal method, which comprises the following steps: (a) taking a proper amount of industrial aluminum hydroxide, putting the industrial aluminum hydroxide into a slurry tank with a stirring device, then adding hot water, and uniformly conducting stirring to obtain slurry with certain solid content; (b) pumping the slurry in the step (a) into an autoclave with a stirring structure through a slurry pump, introducing steam for pressurizing, maintaining the pressure, and conducting stirring for hydrothermal reaction; (c) after the reaction is completed, conveying a product in the step (b) into a cooling buffer tank with a stirring structure for cooling; and (d) pumping the product in the cooling buffer tank into a flat plate filter through a slurry pump, and conducting filtering, washing and drying to obtain the ultralow-sodium boehmite. The embodiment