Research On Competitive Absorption Of H₂S And CO₂ In Wet Desulphurization Of Blast Furnace Gas And Air Catalytic Oxidation Of Desulphurization Wastewater

To promote the implementation of ultra-low emissions in the iron and steel industry,blast furnace gas is subjected to source desulphurization."Catalytic hydrolysis+wet desulphurization"is a technology with high capacity and high speed and is widely used in the process of fine desulphurization of blast furnace gas.In this paper,we focus on the problems of high lye consumption,limited desulphurization efficiency,and the difficulty of harmless treatment of desulphurization wastewater in wet H2S removal,and investigate the influence of the competitive absorption of H₂S and CO₂on the wet desulphurization process of blast furnace gas by combining the differences between H2S,CO_2,and lye reaction process,and study the influence of two factors,namely p H and liquid to gas ratio,on the absorption process of H₂S and CO₂.The preparation of catalysts for the efficient catalytic air oxidation of desulphurization wastewater at low temperatures and atmospheric pressure,makes the toxic and harmful untreatable Sulphur ions transform into non-toxic and harmless easily treatable sulfates and avoid causing secondary pollution.The main conclusions of this paper are as follows:（1）High concentrations of CO₂will weaken the desulphurization capacity of the desulphurizing agent,reduce the efficiency of wet desulphurization,accelerate the consumption of lye,and produce a large amount of wastewater that is more alkaline and does not have desulphurization capacity.However,the low concentration of H₂S in blast furnace gas has less impact on the CO₂removal rate.When the p H of the lye is<8.5,mainly H₂S is removed,the CO₂removal rate is low and the selectivity factor S is large;when the p H of the lye is>8.5,the removal rate of both H₂S and CO₂is increased,but the selectivity of H₂S is also reduced.By increasing the number of showerheads and increasing the liquid-to-gas ratio,the removal rate of both H₂S and CO₂will increase,but the selectivity will decrease.The slurry p H=10 and the liquid-to-gas ratio of 3.8L/m³is the competitive absorption equilibrium point under these experimental conditions,where both the desulphurization efficiency and the lowest CO₂removal rate of 2.52%can be achieved.（2）The efficiency of air oxidation alone for the oxidation of desulphurization wastewater is extremely low.Reducing the bubble diameter and increasing the temperature appropriately can improve the oxidation efficiency,but the improvement is limited.The single metal oxide catalyst Fe Ox,consisting mainly of Fe₂O₃,catalyzed the oxidation of desulphurization wastewater with an efficiency of 57.9%.Mn Ox,consisting mainly of Mn₂O₃,Mn₃O_4,and a small amount of Mn₅O₈,catalyzed the oxidation of desulphurization wastewater with an efficiency of 62.3%.（3）The optimum Fe:Mn ratio of 1:1 was selected and the catalytic oxidation efficiency of the composite catalyst reached 97.5%at low temperatures and atmospheric pressure.The Fe:Mn ratio of 1:1 was found to have an irregular lamellar and acicular interwoven structure with a large specific surface area of 40.96 m²/g.The main components were Mn₃O₄,Fe₃O_4,and Fe₂O₃,and the adsorbed oxygen content was high,which made the composite catalyst more active than the single metal oxide catalyst.It can be easily separated from the water by magnet adsorption,which reduces catalyst depletion.