Patents
The invention provides a process for the precipitation of crystalline boehmite (Al203.H2O) from supersaturated sodium aluminate liquor by adding crystalline boehmite seed at a temperature as low as 50 °C under atmospheric pressure condition. The production of boehmite at such a low temperature has been effected by lowering the AI203/Na2O ratios equal to or below to 0.95. For AI203/Na2O ratio more than or equal to 1.00, the minimum temperature, at which boehmite precipitated is 85 °C to 90 °C when no additive is used. Addition of tartaric acid has helped in reducing the boehmite precipitation temperature to 50 °C for liquor having A/C ratios of 1.0 and more. The innovation is useful for finding an alternative to existing Bayer process by producing alumina through boehmite precipitation method.