Novel product-adjustable technology using Wellman-Lord method coupled with sodium-alkali for SO2 removal and regeneration from smelting gas

Abstract A product-adjustable method for desulfurization and regeneration was proposed in this study. Two stages of SO2 absorption combined the sodium-alkali and Wellman-Lord methods. The products could be recycled as valuable pure SO2, H2SO4, or Na2SO3. The absorption characteristic and the regenerative behavior with Na2SO3 solution were investigated. The influences of various temperatures, oxygen concentration, and absorbent concentration in SO2 removal were studied respectively. Na2SO3 exhibited SO2 removal efficiency higher than 99% and maintained it with the temperature range of 25–60 °C. Oxidation of Na2SO3 harmed its absorption ability. Ascorbic acid realized good oxidation inhibition effect with concentration less than 0.1%. The utilization rate of Na2SO3 remained nearly 100% at different concentrations. Meanwhile, desorption of saturated absorbent (mainly NaHSO3) was studied. The desorption proportion rose with the increasing concentration of HSO3- while slightly changing with desorption temperature. Ascorbic acid could raise SO2 regeneration concentration higher than 2.5%. Part of NaHSO3 could be regenerated to release high-concentration SO2 and fully used in further absorption. The system showed good regeneration performance for at least 4 rounds and stabilized then. Therefore, the improved regeneration technology realized the reuse of Na2SO3 and the recycling of pure SO2.