ABSTRACT
This chapter examines the composition, manufacture, and properties of the major mixed fertilizers used today. The melt granulation process developed in the 1960s was first used to produce granular ammonium phosphates. Chemical incompatibility of intermediates may cause the mixture to heat up, water to form, gas to evolve, and caking. The granular fertilizers are dust-free, and each granule has similar composition and particle size. These free-flowing fertilizers were needed for the new fertilizer application equipment that was being developed. Fluid fertilizers are of two types: solutions and suspensions. The important advantages of producing and marketing fluids are simplicity of the mixing facilities and ease of handling. The principal intermediates used for making liquid NPK fertilizers are urea, urea-ammonium nitrate (UAN) solution, ammonium and orthophosphate or polyphosphate solutions, and finely ground soluble KCL. The liquid fertilizers usually have a brown or green color derived from the wet-process acid used in their preparation.
