Experimental Study On Desulfurization And Denitrification Of Steel Slag-based Activated Carbon

The sintering flue gas emitted from the sintering process of the steel plant contains a large amount of pollutants,such as SO₂,NO,dust and dioxins.These pollutants not only cause serious harm to the living environment of animals and plants,but also endanger people's health.With the pursuit of health and green environment and the implementation of the stricter national standards for sintering flue gas emissions in the steel industry,it is imperative to control the sintering of flue gas.At present,the desulfurization and denitration technologies of flue gas are mainly divided into two categories:dry flue gas desulfurization and denitration including solid phase absorption/regeneration method,gas/solid catalytic method,absorbent spray technology,electronic activated oxidation method;wet flue gas desulfurization and denitrification known as semi-dry spray desulfurization and denitration technology.Among them,dry desulfurization and denitration of flue gas mainly removes and adsorbs sulfur and nitrogen oxides in flue gas by carbonaceous materials such as activated carbon?coke?.Based on the activated carbon desulfurization and denitration method,the steel slag-based activated carbon was prepared by mixing steel slag with activated carbon and the flue gas desulfurization and denitration experiments were carried out.The experimental research not only considers the rational utilization of waste steel slag in steel plant,but also discusses the catalytic adsorption of steel slag in steel slag-based activated carbon and its influence on the performance of activated carbon.The experimental study on desulphurization and denitration of sintering flue gas with steel slag-based activated carbon was carried out in an electric heating quartz glass fixed bed reaction device.The effects of reaction temperature,SO₂concentration,NO concentration,O₂ content and H₂O content on the desulfurization and denitration performance of slag-based activated carbon catalyst were investigated.At the same time,the effects of the load of Al₂O₃?V₂O₅ on steel slag-based activated carbon were also considered.The properties of the absorbents were characterized by the X-ray diffraction?XRD?,the Brunauer-Emmett-Teller?BET?,and the X-ray fluorescence?XRF?,scanning electron microscope?SEM?,Laser diffraction particle size analyzer?LDPSA?,Fourier transform infrared spectroscopy?FTIR?in order to build correlation with the catalytic performance of steel slag-based activated carbon.The experimental results show that the steel slag-based activated carbon has a certain removal efficiency for SO₂ and NO without NH₃ in the simulated flue gas.79%desulphurization efficiency and 34%denitration efficiency were achieved at a total gas flow rate of 600 mL/min which contain 600 ppm of SO₂,400 ppm of NO and 15%of O₂ at 120^oC.When NH₃ was introduced at[NH₃/NO]=1,the conversions of SO₂and NO increase to 100%and 44%respectively.With the increases of reaction temperature,the denitration efficiency decreased gradually and the desulfurization efficiency remained at 100%.It was found that the denitration efficiency decreased gradually with the increase of SO₂ concentration.When the initial SO₂ and NO concentrations were 400 ppm respectively,52%denitration efficiency was obtained.However,the NO conversion decreased gradually with the concentration increase of SO₂.When the initial SO₂ concentration was fixed,the denitration efficiency decreased with the concentration increase of NO.It was found that the removal efficiency of desulfurization and denitration increased with the increase of O₂ content.The experimental results showed that the decrease of the denitration efficiency with the increase of H₂O content.44%denitration efficiency was obtained without H₂O and the denitration efficiency dropped to 35%at the H₂O content of 10%.However,the desulfurization efficiency remained unchanged.It showed that the more depression of H₂O content on the NO absorption of steel slag-based activated carbon.The experimental results also found that the load of Al₂O₃ and V₂O₅ onto steel slag-based activated carbon catalysts can increase the removal efficiency of SO₂ and NO.When the content of Al₂O₃ in steel slag-based activated carbon was 20%,the improvement of the absorption performance of steel slag-based activated carbon was most obvious.The addition of Al₂O₃ provides more active sites for some active substances which can effectively inhibit the aggregation of ammonium salts,provide reaction gases and more transport channels.Combined with steel slag-based activated carbon to prepare steel slag-based material catalytic adsorbent,the denitrification rate reached 48%at this time.With the increase of V₂O₅ content,the denitration rate of steel slag-based activated carbon increased.It can be attributed to the strong oxidizing property and strong adsorption to NH₃ and NO under low temperature conditions.When the content of V₂O₅ was 10%,the denitration rate was 46%.