Surface Coated Urea with Bio-Degradable Materials Using a Fluidized Bed

Due to the high solubility rate of urea in water, a noticeable portion of this fertilizer migrates into the underneath layers of soil and will be out of access of plants. This leakage not only is non-economic but also is dangerous for the environment. To avoid this leakage, different methods have been used which one of more applicable methods is the coating of the urea for controlling its solubility rate in the water. In this paper, xanthan gum and alginate powder were used as coating materials for urea pellets and the effects of these coatings on the releasing rate of urea was investigated. Single and double layer coatings were produced in a gas-solid-liquid fluidize bed. The best result has been obtained from the two-layer coating of xanthan gum and alginate. The results showed that this coating increases the urea release time up to 12 days.