The invention discloses an alumina making method at raw material of coal gangue, which comprises the following steps: grinding the coal gangue; leaching the coal gangue through sodium hydroxide solution after sintering at high temperature; filtering the residual; producing Al (OH) 3 deposition the residual through carbon dioxide; dewatering Al (OH) 3 to produce Al2O3 at high temperature. The procedure is easy to control to recycle the technological waste water, which realizes zero drainage of industrial production. |