Ammonium sulfite is recommended for use as an agricultural fertilizer
The (NH4)2SO3 solution only requires simple cooling to yield the (NH4)2SO3·H2O crystalline product, further simplifying the process.
Recycling ammonium sulfite from sulfuric acid tail gas is economically profitable.
Table 9 compares the production costs of manufacturing solid ammonium sulfite using various ammonia sources. The table clearly shows that using liquid ammonia or ammonia water as the ammonia source results in significantly lower production costs compared to using ammonium bicarbonate. This difference is primarily due to the substantial price variations among the three ammonia sources, particularly the higher cost of ammonium bicarbonate. Calculated per kilogram of nitrogen (N), the price ratio of the three ammonia sources is: ammonium bicarbonate: ammonia water: liquid ammonia = 0.89:0.61:0.40 (yuan).
The nitrogen content of solid ammonium sulfite products is comparable to that of solid ammonium sulfate products. Currently, the market price for solid ammonium sulfate typically ranges from 180 to 250 yuan per ton (varying by region). If the price of solid ammonium sulfite is also set at 180–250 yuan per ton depending on the ammonia source used, manufacturers can achieve economic break-even.
