Synthesis of zeolite X from waste sandstone cake using alkali fusion method

Abstract

During quarrying, waste stone cake is discharged as industrial waste. In this study, we attempted to convert waste sandstone cake to zeolitic materials using alkali fusion method. By varying the experimental conditions different types of the product were obtained, e. g. zeolite-X, zeolite-P, hydroxysodalite, tobermorite, and nepheline. The siliceous minerals in the cake were transformed into soluble phases, while calcite remains in the solid after 24-agitation following alkali fusion. The optimum condition of zeolite-X synthesis in the product is that the mixed ratio of NaOH to the cake is 1.6, fusion temperature is 600°C, and heating time at 80°C is less than 12 h. The results of the sorption experiments suggest that the product can be applied in environmental field such as the removal of pollutant. © 2009 The Japan Institute of Metals.