Desilication of Sodium Aluminate Solutions from the Alkaline Leaching of Calcium-Aluminate Slags

The desilication of sodium aluminate solutions prior to precipitation aluminum tri-hydroxides is an essential step in the production high purity alumina for production. This study evaluates derived from leaching calcium-aluminate slags with carbonate, using CaO, Ca(OH)2, and MgO fine particles. influence amount CaO used, temperature, comparisons Ca(OH)2 were explored. Laboratory scale test work showed that optimal conditions this process 6 g/L at 90 °C min. resulted 92% Si being removed as little 7% co-precipitation Al. other desilicating agents, namely MgO, also proved effective removing but slower rates higher amounts Al co-precipitated. characteristics solid residue obtained after indicated via formation hydrogarnet, Grossular, hydrotalcite dominant phases respectively.