Production of ammonium sulfate fertilizer from FGD waste liquors. First quarterly technical report, [January--March 1995]

Hydrolysis of Nitrogen-Sulfur Containing Compounds (N-SCC) derived from desulfurization liquors was carried out at high temperature and pressure with varying sulfuric acid concentration in order to determine the influence of temperature and acid concentration on time required for complete hydrolysis. An ammonia specific electrode (gas sensing) was used to monitor the concentration of ammonium ion in the hydrolyzed liquor. The results indicated a large shortening of time for complete hydrolysis of the Ca salt of N-SCC but varying acid concentration did influence the rate of hydrolysis. Since the physical-chemical analysis of the N-SCC obtained by re-liming the waste scrubbing liquor (containing the Fe-EDTA complex) was found to contain a high quantity of sodium, the N-SCC is believed to be a double salt of calcium and sodium. The final product, (NH{sub 4}){sub 2}SO{sub 4}, was obtained in experimentation using an evaporative crystallizer. The clean hydrolyzed liquor was neutralized with a strong NH{sub 2} solution before the final crystallization of (NH{sub 4}){sub 2}SO{sub 4}