Granulation of ammonium chloride fertilizer and agglomeration mechanism

The granulation of ammonium chloride (AC) fertilizer has been investigated in a laboratory scale based on the pan granulator at ambient temperature. Significant improvement of granulation efficiency of AC was achieved by using polyaluminium chloride (PAC) as solid binder and urea as granulation additive. Highly charged cations by PAC hydrolysis could reduce the electrostatic force of AC, resulting in efficient particle agglomeration. Analyzing the surface structure and characteristics of the PAC and AC granules revealed their interactions, which lead to the formation of aggregate nucleus. Furthermore, PAC contained a larger number of active groups, which served as bridges to form particle-polymer-particle complex, and facilitated the growth of particle. Meanwhile, urea and AC could react with each other to form stable inclusion complex which also had pronounced effect on the increase of granulation rate for AC. [Display omitted] •Ammonium chloride fertilizer was granulated by using polyaluminium chloride as binder.•The addition of urea improved the degree of granulation.•Effect of process variables on granulation was studied.•Agglomeration mechanism based on the chemical and physical interactions was discussed.