Open AccessProduction of ammonium sulfate fertilizer from FGD waste liquors. Quarterly technical report, October 1, 1994--December 31, 1994
Author(s) -
Alan D. Randolph,
Santanu Mukhopadhyay,
E. Unrau
Publication year - 1994
Language(s) - English
Resource type - Reports
DOI - 10.2172/371208
Subject(s) - lime , crystallization , flue gas desulfurization , slurry , chemistry , precipitation , mother liquor , scrubber , ammonium sulfate , ammonium , mineralogy , metallurgy , chromatography , materials science , organic chemistry , physics , meteorology , composite material
During this quarterly period, an experimental investigation was performed to study the precipitation kinetics and hydrolysis characteristics of calcium imido disulfonate crystals (CaADS). The CaADS crystals were precipitated by a metathetical reaction of lime, supplied by Dravo Lime Co., with flue gas desulfurization (FGD) scrubber waste liquor. Before approaching for the continuous Double Draw-Off (DDO) crystallization studies, the influence of a Dravo lime slurry on the precipitation characteristics of N-S compounds will be established. A series of N-S compound batch crystallization studies were completed in a wide range of pH (7.0--9.0), and the influence of pH on the amount of lime required, as well as the amount of precipitate obtained, was investigated. Although the amount of precipitate increased with increase in solution pH, the safe or optimum pH for the precipitation of CaADS lies in the vicinity of 8.2 to 8.3. For studying the crystallization characteristics of CaADS crystals, a bench scale 7.0 liter DDO crystallizer was built. DDO crystallizer is found to be superior compared to Mixed Suspension Mixed Product Removal (MSMPR) crystallizer. The precipitated crystals were analyzed for elemental composition by chemical analysis. The crystals were also examined under optical microscope for their morphological features. The present studies confirmed our prediction that N-S compounds in the waste liquor can be precipitated by a reaction with lime slurry. The precipitated crystals were mostly calcium imido disulfonate