大量元素水溶肥中水不溶物的形成原因探讨

为了尽可能降低甚至消除尿素基大量元素水溶性肥料中的水不溶物,对不同条件下制备的大量元素水溶肥以及其中的水不溶物进行研究。结果表明,在较高温度下制备的水溶肥样品,其pH值和水不溶物含量要明显高于较低温度下制备样品;X射线衍射分析结果显示,两种温度下制备的水溶肥样品的衍射图也出现了一些差别。根据分析结果,提出水不溶物的形成机制为:在较高温度下制备样品时,尿素缩合反应产生的氨气被吸收,使体系的p H值升高,升高的pH值以及高温的共同作用导致了水溶肥中的部分微量元素络合物中的金属离子参与磷酸盐的固相沉淀反应,导致水不溶物含量升高。

Formation mechanism of water-insoluble substances in water-soluble fertilizer containing N,P, K

In order to decrease the content of water-insoluble substances in urea based water-soluble fertilizer,water-soluble fertilizer samples are prepared from N,P,K and micronutrients containing compounds under two conditions.The structure and its change of both water-soluble fertilizer and water-insoluble substance are comparatively investigated.The results shows that the content of water-insoluble substance in water-soluble fertilizer and pH value of water-soluble fertilizer prepared at higher temperature are higher than those prepared at lower temperature;XRD detection displays that the XRD patterns of the two samples are different considerably.Based on the results,it is concluded that the absorption of evolved ammonia caused by the condensation of urea is responsible for the pH change during preparation of water-soluble fertilizer,and then the synergetic effects of higher pH and higher temperature lead to the higher water-insoluble substance content by the reaction of chelated metal with dihydrogen phosphate salt.