Effect of process parameters and agglomeration mechanisms on NPK compound fertiliser

• Published in: Powder technology Vol. 247; pp. 8 - 13
• Main Authors: Xue, B.C., Hao, Q., Liu, T., Liu, E.B.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-10-2013; Elsevier
• Subjects: Agglomeration; Applied sciences; Binders; Calcium carbonate; Chemical engineering; Exact sciences and technology; Fertiliser; Granular materials; Granulation; Miscellaneous; Reactors; Scanning electron microscopy; Sintering, pelletization, granulation; Solid-solid systems; Sulfates; Sulphuric acid; Viscosity; Granulation; Fertiliser; Calcium carbonate; Sulphuric acid; Viscosity; Scanning electron microscopy; Drum; Agglomeration; Binders; X ray diffraction; Operating conditions; Surface structure; Chemical reaction; Granule; Porosity; Coalescence; Strength
• ISSN: 0032-5910; 1873-328X
• DOI: 10.1016/j.powtec.2013.06.027

The granulation characteristics of a calcium carbonate–industrial sulphuric acid-based NPK compound fertiliser have been investigated in a bench scale drum granulation unit. It was found that the granulation of the fertiliser was correlated with both the calcium carbonate's properties and the system's operating parameters, especially the industrial sulphuric acid content and viscosity which were found to govern the granulation process. The surface structure and characteristics of the NPK granules were analysed by scanning electron microscope (SEM) and X-ray diffraction (XRD). The results showed that calcium sulphate formed the coalescence kernel with its high porosity and strength generated by a chemical reaction in the granulation process. Meanwhile, urea sulphate, as a liquid binder, improved the solution–solid phase ratios and binder viscosity.
The purpose of this paper was to illustrate the effect of the operating conditions, and to examine the main forces that lead to the mechanism of agglomeration during drum granulator operation. It was found that the granulation of the fertiliser was correlated with both the calcium carbonate's properties and the system's operating parameters, especially the industrial sulphuric acid content and viscosity which were found to be governing the granulation process. [Display omitted]
•Calcium carbonate powder was correlated with granule size distribution.•Content and viscosity of sulphuric acid were correlated with granule size.•The chemical reaction among raw materials changed the microstructure of granule.