Influence of coating and granulation techniques on caking, hygroscopicity, and other physicochemical properties of chelate-enriched CAN fertilizer granules

The integration of chelated micronutrients into calcium ammonium nitrate (CAN) fertilizer granules poses challenges for thermal stability and storage performance. This study compares two incorporation techniques, mechanical homogenization (G) and surface-layer application (L), for Cu, Mn, and Zn chelates in EDTA and IDHA forms. Thermal analysis (TG-DTA-MS) revealed that systems with 0.2 mass% chelates maintained acceptable thermal behavior due to higher dolomite content, whereas 1 mass% systems exhibited increased exothermicity and reduced stability. The method of incorporation and chelate type significantly affected decomposition characteristics, phase transitions, and granule behavior. Granules produced via method G showed higher initial crushing strength but greater hygroscopicity and caking tendency over time. In contrast, coated L-type granules demonstrated improved resistance to moisture uptake, reduced caking under thermal cycling, and better mechanical durability during storage. These findings provide insight into the effects of chelate addition and processing method on the physicochemical and powder handling properties of CAN-based fertilizer granules. • Coated CAN granules exhibited reduced hygroscopicity and lower caking tendency. • Granulation method influenced crushing strength and moisture sensitivity. • EDTA chelates caused greater thermal decomposition intensity than IDHA. • Dolomite addition increased thermal stability in chelate-enriched AN systems. • Chelate incorporation route strongly affected storage performance of CAN granules.