Abstract: The invention relates to a process for upgrading andalusite present in an ore containing it. The process involves separation from other silicates by froth flotation to obtain a concentrate whose content of andalusite is higher than 90%. It is characterized by the fact that the process comprises at least the following steps:(a) grinding as may be required and placing in pulp of the ore containing the andalusite(b) pre-conditioning the ore containing the andalusite by keeping the pH of the aqueous phase of the pulp at a value of below 3.50, the solids ratio in the pulp being higher than 30% (by weight)(c) conditioning the preconditioned ore pulp for at least 10 minutes after addition of an alkyl sulfonate;(d) dilution as may be required of the pulp to bring it to a solids ratio comprised between 15 and 30% (by weight);(e) froth flotation by bubbling calibrated air bubbles therethrough in manner known in itself, the froth flotation proper lasting at the most 10 minutes.