Liquid and Solid Compound Granulated Diurea Sulfate-Based Fertilizers for Sustainable Sulfur Source.

Design and manuf. of high nitrogen content sulfur-contg. fertilizers is of crucial importance in sustainable food and energy crop prodn. The availability of large elemental sulfur amts. in oil refining and natural gas processing facilities, in combination with decreasing sulfur deposition into soil from natural and anthropogenic sources in a bioavailable sulfate form, calls for innovative engineering solns. that bridge this gap via sustainable sulfur processing. Diurea sulfate-based liq. and compd. solid granulated fertilizers were synthesized in this work, and their resulting physicochem. properties were detd. First, phase compositional information on the 2CO(NH2)2·H2SO4-CO(NH2)2-H2O ternary system was measured, and high nitrogen content, ∼15:1 N:S ratio liq. fertilizer grades, were established. Next, diurea sulfate granulation expts. using (i) dolomite, (ii) byproduct material after the phosphoric acid extractive prodn., CaSO4·0.5H2O, and (iii) dolomite combined with diammonium phosphate, (NH4)2HPO4, and potassium chloride, KCl, were performed. Using diurea sulfate, 16-16-16-5.5(S)-0.4(MgO)-0.6(CaO) compd. granulated fertilizers were successfully obtained, and time-resolved changes in their cryst. phase compn. during granule curing were monitored using XRD. The granule crushing strength measured increased to 3.800 MPa within the 30 day storage thus resulting in high quality fertilizer material. [on SciFinder(R)]