Chemical reaction of urea sulfate system at different ratios and temperatures. The results show that crystals with fixed melting point can be formed when the molar ratio of sulfuric acid to urea is 1∶ 1 and 1∶2 0 at room temperature. Its phase transition point temperature is between sulfuric acid and urea, and its phase transition heat is much less than that of urea. At 80 ~ 90℃, the aqueous urea sulfate system will undergo hydrolysis reaction, the process rate is second-order, and the hydrolysis rate is much higher than that of the aqueous urea system. When the temperature is higher than 65438 050℃, the urea sulfate system reacts to form ammonium sulfamate. In engineering design and application, the residence time of urea sulfate system should be strictly controlled at 80 ~ 90℃, and the system temperature should not exceed 65438 050℃.

The reaction of phosphate rock with the mixture of sulfuric acid and urea can effectively control the pollution of fluorine to the environment while producing compound fertilizer. This is a new clean chemical technology. It was developed by France in the 1990s, showing good technical, economic and environmental benefits [1], and has attracted domestic attention in recent years [2]. The core of this technology is to use urea sulfate solution (1mol mixture of sulfuric acid and some mol urea).