Influence of cellulose additive on the granulation process of potassium dihydrogen phosphate

Abstract

KH2PO4, which was manufactured using conversion of KCl and NH4H2PO4, is a concentrated crystalline chlorine-free phosphorus and potassium fertilizer. It is usually used as a component of a liquid complex fertilizer, because KH2PO4 crystals melt very easily, and have very high hygroscopicity and caking effect. Granulated products are considerably more convenient than powders, but KH2PO4 crystals are pure, hardly agglomerate, therefore they need a proper binder. This study aims to investigate the influence of cellulose additive and other different conditions on the granulation process and on the properties of the granulated product. Potassium dihydrogen phosphate was granulated using three different types of granulators (rotary, a fluidized bed and a drum) and by changing the amount of water used for irrigation purposes. The achieved results indicate that in order to obtain granulated potassium dihydrogen phosphate with optimal properties, the use of water does not suffice; therefore, another binder (cellulose) was used in order to improve physical and mechanical properties of the granules. It was determined that cellulose additive (5%) improves some properties of the fertilizer, such as the amount of marketable fraction, SGN, pH, and also reduces the hygroscopicity of the fertilizer granules about 2 times. But cellulose additive does not improve the static strength of granules and bulk density.