Ammonium Sulphate – A By-product of Coal Coking Process...

Ammonium Sulphate – A By-product of Coal Coking Process Ammonium sulphate is produced as a by-product during removal of ammonia (NH3) from the raw coke oven gas generated during the coking of the metallurgical coal in by-product coke ovens. Its industrial production began over a century ago, as by-product in gas cleaning in coke and coal gasification plants. Ammo­nium sulphate is produced as crystals. It is an organic, white odorless solid and crystalline salt with a number of commercial uses. It contains around 21% nitrogen (N2) and 24% sulphur (S). The Chemical Abstracts Service (CAS) registry number for ammonium sulphate is 7783–20–2. Its EC number is 231-984-1. Its IUPAC ID is Diazanium sulfate. It is currently classifiable under Harmonized Tariff Schedule of the United States (HTSUS) subheading 3102.21.0000. This process by which ammonium sulphate is produced consists of absorption of ammonia in the coke oven gas in a solution of ammonium sulphate and sulphuric acid. The absorption reaction is 2NH3 + H2SO4 = (NH4)2SO4. The ammonium sulphate produced by the reaction of NH3 with H2SO4 is recovered by crystallization. The crystals are then centrifuged, washed and dried. Since ammonium sulphate is produced as a by-product during the recovery of ammonia from coke oven gas, there are normally a lot of impurities from different sources. These are organic impurities as well as the inorganic impurities. The combined effects of these impurities are complex and influence the purity and the crystal shape and size. Ammonium sulphate is available in a variety of grades, including granular and standard grades. Granular grade accounts for the vast majority of the market.  Its relatively large particle size (typically 2.5 mm) makes it well suited for mixing with other fertilizers and application by spreading machines.  Standard grade has a smaller particle size (less than 2 mm) and...