Physico-сhemical nanomaterials science
Effect of temperature on formation of nanoporous structure of granule shell in technology of obtaining organo-mineral fertilizers
M.P. Yukhymenko, R.O. Ostroha, A.E. Artyukhov
Processes and Equipment of Chemical and Petroleum Refinery Department, 
Sumy State University, Rymskogo-Korsakova str., 2, Sumy-40007, Ukraine. 
E-mail: r.ostroga@pohnp.sumdu.edu.ua

At present, the technologies of obtaining two-component fertilizers, which are granules with a solid mineral core and a porous organic shell are becoming more and more popular [1, 2]. At the same time, the effective period of encapsulated fertilizers is important, which is determined by the time of release of the target components from the shell. Depending on the characteristics of the porous structure of the shell, features of the target components diffusion are developed through micropores and macropores with an effective pore radius of less than 10-9 micron and more than 10-7  micron, respectively. Thus, by changing the pore size and its specific surface, we can obtain several varieties of encapsulated granules (with the effective period: 3–4, 5–6 and 12–14 months).
The formation of the porous shell structure with various modification features is influenced by the temperature regime of the granulation process [3]. Analytical dependences for calculating the temperature cut-out of a two-layer granule “solid core – porous layer” are obtained from the differential equation of unsteady-state thermal conductivity of Fourier. The peculiarity of these equations is that they contain the coefficient of constrained thermal conductivity through the porous layer, which depends on the layer porosity, the size of pores and their specific surface.

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