Recent Developments in Granulation I

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This document provides an overview of recent advancements in granulation technology, specifically focusing on granulation plants and their conversion processes. The granulation industry has witnessed an increase in the number of plants as companies previously producing pulverized mixtures have switched to batch granulation methods. This transition involves modifying batch mixers, installing ammonia and acid distributors, and utilizing rotary coolers for product cooling. Producers with medium-sized granulation plants have adopted pre neutralizers and scrubbers to enhance their production capabilities, leading to the manufacturing of diammonium phosphate granules and higher annual production volumes. The shift towards complete-grade handling stations has been observed among these companies. Additionally, some producers have transformed their batch ammoniators into continuous ammoniator-granulators to meet higher production demands. Various strategies have been employed to improve the efficiency and performance of granulation equipment. Operators have experimented with different materials for sparger pipes, with stainless steel and Hastelloy being preferred due to their longer lifespan and improved distribution of ammonia and acid within the granulator. Removing internal rings in ammoniator-granulators has been found to have no negative impact on granulation efficiency, while longer distributors have helped minimize nitrogen loss during the process. Several techniques have been implemented to prevent material caking, including rubber linings, flaps, knockers, and oscillating or spiral scrapers. These mechanisms effectively remove buildup from the walls of the ammoniator-granulator, ensuring smooth operation. Furthermore, a patented device for cleaning and positioning sparger bars has been introduced, enabling their rotation without equipment shutdown and facilitating maintenance. Integrating pre-neutralizers and scrubbers have allowed manufacturers to utilize larger quantities of phosphoric acid and ammonia to produce diammonium phosphate grades. The TVA process, involving partial ammoniation in a pre-neutralizer and complete ammoniation in the ammoniator-granulator, has shown promising results with high ammoniation levels and increased fluidity. This process allows for significant phosphoric acid consumption, resulting in high-quality fertilizers. Bulk handling stations have gained popularity among companies producing high-analysis grades, such as 8-24-2, 10-20-30, 12-24-24, and 20-10-10. These stations optimize transportation costs and enable the marketing of products over longer distances. Typical bulk handling stations consist of storage buildings with multiple bins or elevated storage tanks, utilizing conveyor systems for material unloading, storage, and loading onto bulk trucks. Cost studies indicate that constructing bulk handling stations alongside granulation plants is a competitive alternative to bulk blending, especially for high-analysis grades. However, the economic viability of this system relies on a high material movement, preferably exceeding 70,000 tons. At this scale, the cost-effectiveness of granulation with bulk handling stations approaches that of bulk blending. Collapse
Ammonia, Technology