Fixing sulfur dioxide by feeding calcine oxide into the rotary volatilization kiln in zinc smelting plant

Sulfur dioxide (SO 2 ) is a toxic pollutant and its fixation is a high cost but imperative task for sulfide metallurgy industry. Although being a mature technology for on-line fixation of SO 2 by limestone injection in coal-fired boilers, its application is rarely investigated in the sulfide metallurgy plant. Extending this technology to the metallurgy industry is highly plausible, but with the feasibility and practicability waiting to be uncovered. Herein, feeding CaO into the rotary volatilization kiln as SO 2 -fixation agent is demonstrated to be an efficient in-furnace desulfurization strategy for zinc smelting plant. The sulfur distribution within the entire smelting process is systematically analyzed, determining that the critical procedure for pressuring the desulfurization system is the rotary volatilization kiln. The thermodynamics analysis shows that addition of CaO is feasible for SO 2 fixation by forming CaS or restraining the reductive decomposition of SO 4 2− . The industrial tests, including the online monitoring of kiln flue gas and kiln slag analysis, validate the thermodynamics analysis, realizing a 24.6% reduction of SO 2 in the flue gas by converting gaseous SO 2 to solid CaS via feeding 20% CaO. The present study highlights an effective strategy for on-line fixing the SO 2 , being a potential way for relieving the desulfurization pressures in zinc sulfide metallurgy plant.