Solid urea exist in different forms: prills, granules and pastilles. Further there is micro grade urea and super grade urea. This paper discusses the different forms of solid urea, its production process and its physical properties.
Caking is an important physical property of solid urea as it can destroy the free flowing property leading to significant extra costs to recover the product. In this paper the theoretical background of the urea caking process is presented and discussed in detail. The process of caking between two urea particles is followed in detail and the diameter and strength of caking bridges between these two particles is measured and discussed.
In a next paper caking in practice and the main parameters to minimize urea caking will be discussed.