1. Compressed carbon dioxide is passed through concentrated ammonia water. The carbon dioxide is then placed under pressure and cooled to precipitate crystals, which are then centrifuged and dehydrated. During purification, the carbon dioxide is dissolved in water and recrystallized by adding ethanol.
2. Carbonation: Ammonia gas is absorbed in water and carbonized with carbon dioxide. The product is then separated and dried to produce ammonium bicarbonate. The chemical reaction equation is: NH3 + CO2 + H2O → NH4HCO3
3. Washed and purified CO2 gas from a lime kiln is passed through ammonia water to saturate it. The product is then centrifuged and dried with hot air to obtain the finished product.
4. A typical small-scale nitrogen fertilizer plant producing ammonium bicarbonate uses anthracite as raw material. Semi-water gas is first produced. After hydrogen sulfide is removed from the semi-water gas, it enters a pressurized shift reaction system. The resulting mixture of nitrogen, hydrogen, and carbon dioxide enters a carbonization tower, where the carbon dioxide reacts with ammonia water with a concentration of approximately 17% to produce ammonium bicarbonate crystals. The ammonium bicarbonate product is then separated by centrifugation. The carbon dioxide-removed feed gas, after further removal of residual carbon dioxide and a small amount of carbon monoxide, enters the ammonia synthesis system. Dry ammonium bicarbonate exhibits a certain degree of stability and good fluidity at room temperature. Some Chinese ammonium bicarbonate plants use airflow drying to dry their product; more plants add crystal modifiers to produce coarser ammonium bicarbonate crystals, thereby improving the operating conditions for liquid-solid separation and reducing the product's moisture content from 5%-5.5% to 2.5%-3.5%, significantly reducing decomposition losses and agglomeration.
