Preparation And Characterization Of High-efficiency Flue Gas Adsorbent From Solid Waste

In this paper,three kinds of industrial solid waste,namely fly ash,calcium carbide slag and refined waste residue,are used as raw materials,and then modified by mechanical grinding,microwave modification,and alkali immersion to prepare high-efficiency adsorbent for sintered flue gas.The properties,adsorption characteristics and adsorption kinetics of adsorbents were studied.The purpose of fast and efficient desulfurization and denitrification of sintering flue gas was achieved.Firstly,two preparation methods of water bath heating hydration and microwave heating hydration were designed by orthogonal experiment.The experimental results are analyzed by the extreme difference method.Considering the optimal removal rate and economy of the adsorbent,a more suitable preparation scheme is selected.It can be seen from experiments that the desulfurization rate of the best adsorbent prepared by the two methods can reach more than 98%,and the denitrification rate can reach 92%or more.The microwave heating hydration method reduced the power consumption by 3.3 kW·h compared to the water bath heating hydration method,and the preparation time was shortened by 11.5 hours.;The optimum conditions for microwave heating hydration method are:the ratio of fly ash and calcium carbide slag is 1.0,the proportion of refined slag is 50%,the microwave hydration power is 400 W,and the microwave hydration time is 1h.The ratio of fly ash and calcium carbide slag is the main influencing factor.Secondly,the performance characterization and adsorption characteristics of the best adsorbents prepared by microwave heating hydration method were studied.The results show that the optimal adsorbent surface is rough,uniform distribution of pores and CaO,and the micropore area and micropore volume are 8.5041 m²·g^-1 and0.00132 cm³·g^-1,respectively.When the ratio of fly ash and calcium carbide slag increases from 0.5 to 1.0,the micropore area increases by about 4 times,and when it increases to 2.0,the micropore area decreases by about 98%;When the proportion of refining waste increased from 30%to 50%,the specific surface area of the adsorbent decreased by about 33%,and when the proportion of refined waste increased to 80%,the specific surface area decreased by about 65%;Under the action of CaO₂,strong chemical adsorption occurred during the adsorption process.The high-efficiency desulfurization time is about 16min when the adsorption temperature is 150²00°C,and the high-efficiency desulfurization time is about 3min when the adsorption temperature is increased to 200²50°C.The effect of the microwave field is beneficial to the adsorption reaction,but the adsorption temperature is about 110°C.Increasing the microwave output power can promote the adsorption reaction.Finally,the adsorption behavior of the adsorbent under conventional heating and microwave fields was analyzed by second-order kinetic model and intraparticle diffusion model,and the speed limit of the adsorption process was clarified.The results show that the fitting kinetics of the second-order kinetic model of the fast and efficient desulfurization stage of the adsorbent under conventional heating and microwave fields are 0.991 and 0.989,respectively.The main control link at this stage is the chemical reaction;The conventional heating adsorption process is more in line with the description of the second-order kinetics,and the fitting degrees are desulfurization of 0.990,denitrification of 0.989.Chemical reactions have a major impact on the rate of adsorption;The presence of a microwave field enhances the adsorption reaction.The overall adsorption process is more in line with the intraparticle diffusion model,and its fitting degree is desulfurization 0.989,denitrification 0.992.At this time,the main speed control link is transformed into internal diffusion.