Method of preparing low-calcium polymeric aluminum chloride water purifier from aluminum ash, hydrochloric acid, and optical red mud

The invention provides a method of preparing a low-calcium polymeric aluminum chloride water purifier from aluminum ash, hydrochloric acid, and optical red mud. The preparation method comprises following steps: burning aluminum ash, calcium carbonate, and/or calcium oxide in an oxidative atmosphere; burning the obtained material, reacting the burned material with hydrochloric acid and optical redmud to prepare slurry containing polymeric aluminum chloride, adding sodium sulfate to carry out reactions; filtering the slurry, wherein the filtrate is the water purifier, washing the filter residues by water, and utilizing the obtained solid slag or stacking /burying the solid slag. A problem that when aluminum is hydrolyzed or acid-hydrolyzed, hydrogen is generated and the hydrogen is combustible and explosive is solved. A problem that when aluminum nitride is hydrolyzed, ammonia is generated and the water purified by the water purifier is polluted by ammonia nitrogen is solved. The low activity alumina, which com