Synthesis of flyash based zeolite-A used as detergent builder

摘要

A homogeneous fusion mixture is obtained by mixing and grinding flyash and caustic soda. The fusion mixture is heated to obtain a fused mass which is cooled, milled and mixed with water, to obtain an alumino-silicate slurry. The slurry is subjected to hydrothermal crystallization to obtain crystalline zeolite which is washed with water and oven dried. Fly-ash and caustic soda are mixed in the ratio of 1:1.2, ground and sodium aluminate or aluminum hydroxide are optionally added to obtain a fine homogeneous fusion mixture. The mixture is heated in an inert vessel at 500- 600 deg C for 1-2 hours to obtain a fused mass which is cooled, milled and mixed in distilled water for 8-10 hours, with simultaneous optional addition of sodium aluminate or alum solution, in the presence or absence of sodium chloride. An amorphous alumino-silicate slurry is obtained by optional addition of zeolite-A seeding. The slurry is subjected to hydrothermal crystallization at 90-110 deg C, for 2-4 hours, to obtain crystalline zeolite which is washed with water and oven dried at 50-60 deg C.