Low Concentrations Of Sulfur Dioxide Gas Absorption And Utilization Of Zinc Oxide Process Research

With the increasingly stringent requirements of the State Environmental Protection and the emission reduction efforts continuing to increase, more urgent requirements for treatment of low concentration of sulfur dioxide are necessary. Enterprises which do not comply with the national environmental policy will soon be eliminated. Taking the smelter tin system as the main object of study, zinc oxide was used for the treatment of low concentration of sulfur dioxide. The main research contents and conclusions are as follows.zinc oxide dust was used as the absorbent of low concentration of sulfur dioxide gas with low-cost, high absorption rate and no secondary pollution. When the average concentration of SO2from flue gas was10844mg/m3, the concentration of SO2in the exhaust was reduced to below300mg/m3after the flue gas was absorbed by zinc oxide dust. The absorption ratio of sulfur dioxide in flue gas by zinc oxide was from97.14%to99.82%,97.69%on average. Zinc oxide dust has good absorption for sulfur dioxide, the SO2concentration in the exhaust could be below the national emission standards.Three methods for processing the absorption product, zinc sulfite, were studied as to air oxidation, thermal decomposition and acidic precipitation. More than92%of the zinc sulfite can be oxidized by air in the ejector to zinc sulfide and enter into solution. The absorption of sulfur dioxide and the oxidation of zinc sulfite can be completed at a relatively low temperature of40～50℃to effectively utilize the air up to29%. The compact injectors are identical for the dispersion and mixing of air in the pulp. With the zinc oxide dust from the homemade boiling furnace as the absorbent, the obtained zinc sulfite solution is satisfied with the requirements of quality control standards in zinc smelting system and can be used as the raw material. The desulfurization ratio is between82to84%during the thermal decomposition of zinc sulfite. The rate of thermal decomposition is very quick at600～650℃which is suitable from the viewpoint of the decomposition rate and energy consumption. The desulfurization ratio can reach98%during the acidic precipitation of zinc sulfite when the final concentration of sulfide acid is50g/L, the reaction temperature is from70to80℃C and the reaction time is0.5h.The cost is low and the concentration of sulfur dioxide for emission is consistent with the national standard with zinc oxide dust as the absorbent of low concentration SO2. The three methods for processing the absorption product have advantages and disadvantages over the whole treatment process and can be selected based on the actual situation.