Stable suspension fertilizers from monoammonium phosphate

Abstract

Research studies conducted at the Tennessee Valley Authority (TVA) have shown that addition of the fluoride ion can improve the physical properties of suspension fertilizers made from monoammonium phosphate (MAP) containing metallic impurities. A study was conducted using fluorosilicic acid, which is a by-product of the phosphate fertilizer industry, as the fluorine source in the production of suspension fertilizers from MAP. The experimental data shown improvements in both viscosity and pourability of 10-30-0 and 11-33-0 grade suspensions made from 11-52-0 grade MAP, using as little as 0.6% fluorine added as fluorsilicic acid. Satisfactory storage time was increased from 30 days to at least 90 days when the extra fluorine was added. A test of this process at a dealer site demonstrated that the pourability of a suspension fertilizer made with MAP was improved. Also, the diammonium phosphate (DAP) crystal size was significantly reduced and the suspension containing fluorosilicic acid had exceptional settling resistant properties. (Slide 1) Stable Suspension Fertilizers From Monoammonium Phosphate, Ewell F. Dillard, James R. Burnell, and Joe Gautney. (Slide 2) My presentation will discuss the background and basic research conducted over the last several years which lead to development of the H2SiF6 process, laboratory tests of the new process, commercial tests of the process of a fertilizer dealer site, environmental considerations, economics, and conclusions.