The dissolved aluminium component extracted from alunite ore by sulfuric acid could be recovered as alum crystal by the addition of ammonium sulfate into the extracted solution, in which the iron component being separated from the one still dissolved. Addition of ammonium sulfate in excess appeared profitable through it decreasing the solubility of alum once formed. The economic recovery of the dissolved aluminium was accomplished when the excess amount of ammonium sulfate addition was adjusted such that the concentration of the unreacted ammonium sulfate remaining in the filtrate would be about 10 %. Heating the extracted solution was necessary after the addition of ammonium sulfate as crystal to dissolve the latter, and in the ensuing step the solution was cooled down to 10 ℃ to crystallize the alum. In such a procedure 97 % of the dissolved alum was recovered, also 97 % of the iron component being left in the solution separated from the aluminium component.