萃余酸氨化制备农用聚磷酸铵的工艺研究

Study on the Preparation of Agricultural Ammonium Polyphosphate

以湿法磷酸溶剂萃取净化过程中副产物萃余酸、合成氨、尿素为原料,通过预中和反应再聚合制备农用聚磷酸铵,考察萃余酸MER值、原料配比、聚合过程升温速率、反应温度对合成农用聚磷酸铵的影响。试验得出:MER值越高越不利于农用聚磷酸铵的合成。反应温度和中和度的提高对产品聚合率指标是有利的。农用聚磷酸铵总养分随着升温速率的升高而降低,但预中和过程的中和度对其影响较小,在一定范围内,n(磷酸)∶n(尿素)为1∶1.2,反应温度197℃时,总养分最高分别为64%和62%。

Using residual acid,synthetic ammonia and urea from the by-products of wet process phosphoric acid solvent as raw materials,agricultural ammonium polyphosphate was prepared by pre-neutralization reaction repolymerization,and the influence of MER value,raw material ratio,heating rate and reaction temperature on the synthesis of agricultural ammonium polyphosphate was investigated.The test shows that the higher the MER value is not conducive to the synthesis of agricultural ammonium polyphosphate.The increased reaction temperature and neutralization degree are favorable for the product polymerization rate index.The total nutrient of agricultural ammonium polyphosphate decreased with the increase of the heating rate,but the neutralization of the pre-neutralization process had little influence on it.Within a certain range,n(phosphoric acid)∶n(urea)was 1∶1.2,and when the reaction temperature was 197℃,the highest total nutrient was 64%and 62%,respectively.