Aluminum sulfate production from ammonium aluminum alum, by 2-stage thermal dehydration, pyrolysis and dissolution in water, giving ammonium ion-free product useful e.g. in water treatment

摘要

Heat-treating ammonium aluminum alum (AAA) to give aluminum sulfate (AS) involves: (a) two-stage dehydration of crystalline AAA, by flash-calcination, then heating for 1-15 minutes in contact with hot waste gases; (b) thermally decomposing the partially dehydrated product; (c) dissolving the product immediately or subsequently in water and optionally (d) isolating crystalline AS. Heat-treating ammonium aluminum alum (AAA) to give aluminum sulfate (AS) involves: (a) two-stage dehydration of crystalline AAA, by flash-calcination for a period of 1 second or less in the flame of a burner at 1000-1500 deg C then heating for 1-15 minutes in contact with the hot waste gases at 250-600 deg C; (b) thermally decomposing the partially dehydrated product at a constant temperature of 500-600 deg C for 15-100 minutes; (c) dissolving the product immediately or subsequently in water at 40-95 deg C to give AS solution and optionally (d) isolating crystalline AS.