Study On Moisture Absorption And Caking And Their Prevention Of Compound Fertilizer

In this paper, as the objects of investigation, series of common compound fertilizer with serious hygroscopic were selected, mainly the nitrogenous compound fertilizer and the urea-based fertilizer which were of some representativeness. A variety of physical and chemical properties such as critical relative humidity at different temperatures, moisture absorbing rate and caking characteristic were determined. The experimental results showed that the critical relative humidity of nitrogenous compound fertilizer and urea-based fertilizer we selected were far lower than urea and ammonium nitrate. At20℃, the critical relative humidity of nitrogenous compound fertilizer15-15-15was57.5%, and that of nitro compound fertilizer24-10-16was50%; the critical relative humidity of urea-based fertilizer16-16-16was47.5%, and that of urea-based fertilizer25-10-16was46%. The phenomenon that the critical relative humidity of urea-based fertilizer reduced was particularly evident. The experiment showed that factors affecting caking was composed of internal factors and external conditions. The main internal factors was the moisture content, moisture absorbing rate and the size of the fertilizer. The external factors include the air humidity, storage temperature, storage pressure and time duration.Self-made moisture anti-absorbing agent was used in the urea based compound fertilizer16-16-16and25-10-16. The result showed that PVA Type had good anti-caking effect on the compound fertilizer25-10-16for it’s good ability to form a membrane, and PEG Type had good anti-caking effect on the compound fertilizer16-16-16for it’s lower water content. The application of alkyl amines showed that, when the amount of alkyl amines was between2%-4%, and paraffin among the anti-caking agents was between20%-22%, the moisture absorption rate and the agglomeration rate of fertilizer has the lowest value.