Ammonium sulfite is recommended for use as an agricultural fertilizer
The ammonium sulfite production process is simple and involves low construction costs.
The ammonia method is used to recover SO₂ from sulfuric acid off-gas, yielding an intermediate solution of NH₄HSO₃·(NH₄)₂SO₃, which can be processed into nitrogen fertilizers via various methods. 1. The solution is neutralized using various ammonia sources (including liquid ammonia, ammonia water, and ammonium bicarbonate), followed by cooling and crystallization to produce the solid product (NH₄)₂SO₃·H₂O.
2、The decomposition using various concentrated acids (including H₂SO₄, HNO₃, H₃PO₄, etc.) releases high-concentration SO₂. The ammonium salt mother liquor (e.g., (NH₄)₂SO₄ mother liquor obtained by H₂SO₄ decomposition) is then evaporated and crystallized to produce the solid product.
3、After adjusting the pH of the semi-finished mother liquor, air is introduced to oxidize it into (NH4)2SO4, which is then evaporated and crystallized to yield the solid (NH4)2SO4 product.
The process flow comparisons of the aforementioned three methods are presented in Table 5. The estimated construction costs for their primary equipment are compared in Tables 6, 7, and 8.
