An improved Wellman-Lord process for simultaneously recovering SO2 and removing NOx from non-ferrous metal smelting flue gas

An improved Wellman-Lord process is developed with electrochemical reactor, which can effectively recycle and reuse SO2 and NOx from flue gas. The process features to (a) remove and recycle NOx while recovering SO2 with the process of electrochemical denitrification; and (b) solve the problem of pipeline blockage caused by oxidation by-products with ammonium- wet absorption method. The crystallization temperature of the absorption solution reduces more than 50.0% after NH4+ is gradually added to Na2SO3. More than nearly 75.0% of (NH4)(2)SO4 added can ensure that it does not crystallize under the same conditions. The crystallization tem perature decreases 44.16% and 54.69% with the absence of SO32- (solute of 20% wt) and HSO3- (solute of 28% wt), respectively, when the interference concentration reaches 80%. The absorption efficiencies of 5% Na2SO3 and 5% (NH4)(2)SO3 reach 98.18% and 98.47% for SO2 and 98.38% and 93.44% for NO2, respectively. Co3O4/Ti cathode exhibits nitrate removal efficiency of 93.67% and ammonia generation efficiency of 85.56%. The concentration of nitrate-N reduces 86.30% and ammonia-N increases 71.40% when the reaction proceeds for 11 h with intermittent injection conditions. The effect of pH on nitrogen removal with the presence of ammonium is also studied.