Open AccessSeparation of flue-gas scrubber sludge into marketable products. Third year, first quarterly technical progress report Quarter No. 9, September 1, 1995--November 30, 1995
Author(s) -
S. Komar Kawatra,
T.C. Eisele
Publication year - 1995
Language(s) - English
Resource type - Reports
DOI - 10.2172/206988
Subject(s) - scrubber , flue gas desulfurization , gypsum , flue gas , chemistry , lime , waste management , sulfur dioxide , sulfur , sulfate , reagent , wet scrubber , sodium sulfite , coal , inorganic chemistry , metallurgy , sodium , materials science , organic chemistry , engineering
To reduce their sulfur emissions, many coal-fired electric power plants use wet flue-gas scrubbers. These scrubbers convert sulfur oxides into solid sulfate and sulfite sludge, which must then be disposed of This sludge is a result of reacting limestone with sulfur dioxide to precipitate calcium sulfite and calcium sulfate. It consists of calcium sulfite (CaSO{sub 3}{center_dot}0.5H{sub 2}O), gypsum (CaSO{sub 4}{center_dot}2H{sub 2}O), and unreacted limestone (CaCO{sub 3}) or lime (Ca(OH){sub 2}), with miscellaneous objectionable impurities such as iron oxides, silicates, and magnesium, sodium, and potassium oxides or salts. These impurities prevent many sludges from being utilized as a replacement for natural gypsum, and as a result they must be disposed of in landfills, which presents a serious disposal problem. Knowledge of scrubber sludge characteristics is necessary for the development of purification technologies which will make it possible to directly utilize scrubber sludges rather than landfilling them. This project is studying the use of minimal-reagent froth flotation as the purification process, using the surface properties of the particles of unreacted limestone to remove them and their associated impurities from the material, leaving a purified calcium sulfite/gypsum product