Effect of CaSO₄ Pelletization Conditions on a Novel Process for Converting SO₂ to Elemental Sulfur by Reaction Cycles involving CaSO₄/CaS – Part I. CaSO₄ Pellet Strength and Reducibility by Hydrogen

Abstract

Abstract A new process for converting sulfur dioxide to elemental sulfur by reaction cycles involving calcium sulfide and calcium sulfate without generating secondary pollutants was developed at the University of Utah. In this process, sulfur dioxide is reacted with calcium sulfide to produce elemental sulfur and calcium sulfate. The latter is reduced by hydrogen to regenerate calcium sulfide. In the present work, the effects of different pelletization conditions for the initial reactant calcium sulfate on the strength and reactivity of the pellets were determined. These pelletization conditions included the type, amount, and impregnation method of catalyst, the binder amount, and sintering. The pellets with the best properties were then reduced with hydrogen in the temperature range 973 to 1173 K, while measuring the kinetics, over several cycles of the two‐step process. Nickel‐catalyzed and fired pellets produced by the use of molasses or cement as a binder showed the highest compressive strength as well as good reactivity during the cyclic tests. The binder amount did not significantly affect the reaction rate.