Production of ammonium sulfate fertilizer from FGD waste liquors. Second quarterly technical report, April--June 1995

In June of this quarter, two 50 gallon drums of ferrous EDTA scrubbing liquor were supplied by Dravo Lime Company (Fort Miami, OH plant) for continuing investigation of the precipitation of N-S containing crystals in the DDO (Double-Draw-Off crystallizer) configuration. In order to further study the influence of design variables on the size of Nitrogen-Sulfur (N-S) containing product crystals, another DDO run was carried out at a higher DDO ratio. Using a DDO ratio of 20 in the current experimental run, the mass mean size of the crystals was found to be 250 {micro}m, which is much higher than that found previously with a lower DDO ratio. The new liquor supplied by Dravo Lime Company was found to have a much lower pH ({approximately}4.5) compared to the previous supply ({approximately}6.8). The liquor was also found to contain higher amounts of sodium and sulfur. However, the liquor still produced N-S containing crystals, thus illustrating the robustness of the process. Hydrolysis experiments were conducted in a one liter jacketed glass vessel, equipped with a temperature controller, using 1 M H{sub 2}SO{sub 4} at 70 C and 80 C under atmospheric pressure. The purpose of these hydrolysis experiments was to evaluate kinetic information and to generate enough hydrolyzed liquor to produce NH{sub 3} gas. The NH{sub 3} gas is then used to neutralize the diluted sulfuric acid solution and precipitate pure ammonium sulfate crystals