Process for production of aluminum hydroxide from ore containing alumina

Abstract

A process for the production of aluminum hydroxide from an alumina-containing ore comprising, in a process for the production of aluminum hydroxide involving extraction of alumina from an alumina-containing ore by an aqueous alkaline solution, supplying a slurry containing the alumina-containing ore at a high solid content which is prepared from a small amount of an alkaline solution together with an aqueous alkaline solution which is so preheated to a temperature that a preheated temperature is enough high to have a temperature after the mixing with the slurry which is higher than an extraction temperature of alumina, simultaneously or after the mixing them, to an extraction apparatus comprising of a tube reactor, extracting alumina from the alumina-containing ore under extraction conditions of a temperature of 120.degree.-160.degree. C. and an extraction time within 10 minutes, separating dissolution residue from an extract solution immediately after the extraction, desilicating the extract solution, and adding seeds of aluminum hydroxide to the extract solution which is desilicated so as to precipitate aluminum hydroxide. By the production process, it is possible to economically produce aluminum hydroxide with little contamination by silica from the alumina-containing ore with a high content of the reactive silica.