硫酸脲分解磷矿反应机理探讨

以硫酸脲分解磷矿是一种新的N、P复肥生产方法,硫酸脲分解磷矿有其特殊的反应机理。利用在线显微摄像与物化分析相结合,可以很好地表征硫酸脲分解磷矿的反应机理。实验表明:硫酸脲与磷矿在液固接触的界面微区进行反应,反应微区内有离解、反应、结晶、复合等过程,并伴随有晶型转变。反应生成的硫酸钙晶体复盖反应粒子表面,形成包裹层增大传质阻力。反应物质通过CaSO40.5H2O晶膜的传递阻力是影响整个反应过程的重要因素。

An Investigation on the Reaction Mechanism of Decomposing Phosphate Ore with Urea Sulfate

The urea-based N-P compound fertilizer manufactured by using urea sulfate to decompose the phosphate ore possesses much better storage behaviors than a bulk blend fertilizer manufactured by directly mixing ureas and phosphate. In this work, the reaction mechanism between phosphate ore and urea sulfate was investigated with in-situ microscopic observation, XRD and reaction conversion determination. The results show that the liquid-solid reaction takes place inside a thin layer near the interfacial surface over the solid particles. With the increase of conversion, a solid gypsum layer covers the surface of un-reacted particles. The reaction mechanism is very complicated. Ionization, crystallization and crystal transfrom exist simultaneously in the reaction layer. The gypsum film is suggested to be in CaSO40.5H2O phase. It induces significant resistance on the mass transfer of reactants.