Boehmites and extremely pure pseudoboehmites, and process for their manufacture

摘要

Ultrapure and homogeneous boehmites and/or pseudo-boehmites, suitable, whether before or after drying and/or calcination, as, e.g., fillers, binders, thickeners, dispersing agents, and the like, are prepared (i) by admixing an amorphous aluminum hydroxycarbonate, itself advantageously prepared by carbonating an alkali metal aluminate with carbon dioxide and then filtering and washing the precipitate which results, with a solution of an acid, a base, a salt, or mixture thereof, with the pH of the resulting reaction medium being maintained at a value of less than 11, (ii) next heating such reaction medium at a temperature of less than 90 DEG C. for a period of at least 5 minutes, and (iii) then heating the reaction medium resulting from the step (ii) at a temperature ranging from 90 DEG C. to 250 DEG C.