Technical Aspects of Suspensions
Achorn, Frank P.
Kimbrough, Homer L.
This document explores the rapid growth and increasing interest in suspensions within the fertilizer industry, focusing on three major reasons for their popularity. Firstly, suspensions allow for producing high-analysis grades with significantly higher concentrations than clear liquids. Secondly, they provide a means of incorporating nutrients into fluid fertilizers. Lastly, suspensions enable the effective suspension of pesticide or herbicide fluids, reducing the need for multiple applications. The production of suspensions typically involves two main procedures: hot and cold mixing. Hot mixing utilizes acid and superphosphates, often combined with ammonia, resulting in heat release during the mixing process. On the other hand, cold mixing involves using materials that do not generate heat when mixed. Various suspension grades, such as 12-12-12, 9-27-9, and 12-15-10, have been successfully produced through hot-mix processes. Different suspensions are created based on the choice of raw materials and the chemical reactions involved. For instance, the neutralization of orthophosphoric acid with aqua ammonia produces ammonium phosphate suspensions, while nitric acid reacted with phosphate rock yields nitric phosphate suspensions. Each type has its advantages and considerations. Although lower in the analysis compared to ammonium phosphate suspensions, Nitric phosphate suspensions offer the benefit of using low-cost raw materials. Triple superphosphate can also be used to produce suspensions, either through ammoniation with aqua ammonia or an ammoniating solution. This approach allows for the utilization of low-cost phosphate and eliminates the need for additional suspending clay. However, the crushing and screening of triple superphosphate pose challenges due to its sticky nature. Additionally, the document describes a continuous hot-mix plant that produces a base ammonium polyphosphate suspension, specifically the 12-40-0 grade. This base suspension is then marketed through cold-mix plants as a liquid fertilizer. With its regional approach, the 12-40-0 suspension marketing system simplifies the supply chain and has gained acceptance in the fluid fertilizer industry.