PRODUCTION OF GRANULAR AMMONIUM SULFATE

PURPOSE:To continuously and quickly granular ammonium sulfate under resolving the problem of producing line size granules thereof by adding a phosphoric acid based or amine-based drug to a solution of ammonium sulfate in an amount more than a prescribed amount equivalent to those of metallic ions as a crystal growth-inhibiting factor and sealing said metallic ion in the solution. CONSTITUTION:A coke oven gas 1 containing NH3 is brought into contact with aqueous solution of sulfuric acid in an NH3-absorbing column 3 to remove NH3 and the NH3 is made to aqueous solution of ammonium sulfate, then fed to tar-separating tank 4 and crystallizing can 6, in turn. In the crystallizing can 6, said aqueous solution of ammonium sulfate is continuously subjected to concentration and cooling, then ammonium sulfate crystal is deposited and grown. As the result, grown ammonium sulfate crystal is separated in the can 6 and made to granular ammonium sulfate 8 through dehydration and drying 7. On the other hand, aqueous solution after deposition of the crystal and approximately saturated solution of ammonium sulfate generating in dehydration are sent to an overflow tank 9, then an aqueous solution of sulfuric acid for NH3-absorption 10 and a metallic ion-sealing solution 11 are added, resultant solution is utilized in circulating. In said case, especially to Fe having inhibiting action on crystal shape improvement, phosphoric acid-based or amine-based drug is used to prevent the production of fine granular size of ammonium sulfate when depositing as the above-mentioned sealing agent.