Research On Steel Slag For CO₂ Sequestration In Fluidized Bed

Carbonation technology,that is the use of metal oxide-containing substances to react with CO2 to generate stable carbonates to achieve CO2 fixation technology,with good technical and economic characteristics,is an important part of carbon capture and storage(CCS).Steel slag is a kind of industrial solid waste produced during the steelmaking process.It contains a large amount of calciium-containing minerals and can replace natural minerals to fix CO2 by carbonation.It is a good CO2 capture material.In this paper,the converter slag,cast residue and electric furnace slag from Nanjing and Maanshan Iron and Steel Co.,Ltd.were selected as raw materials.The chemical composition,mineral composition and microscopic morphology were analyzed by XRF,XRD,SEM,BET and other analytical methods.The results show that the chemical composition of steel slag mainly includes CaO,SiO2,Al2O3,etc.,among which the CaO content is high;the mineral composition mainly includes C2S and C3S,similar to Portland cement clinker;the surface of steel slag is rough and porous,and has certain adsorption capacity.The modified slag was modified by hydration heating method,ethanol solution modification and acetic acid solution modification,and the modified unit adsorption capacity and pore structure characteristics were analyzed.The results showed that the unit adsorption amount order was as follows:ethanol solution conditioning>acetic acid solution conditioning>heating hydration modification>unmodified raw materials.The specific surface area of steel slag after conditioning with ethanol solution was up to 191.5 m2/kg.A steam generator was added on the basis of the fluidized bed to perform carbonation of the modified steel slag to fix CO2,and the temperature and time for the steel slag calcination were investigated at 800?-1h.The carbonation temperature,CO2 concentration,flue gas flow rate,and water vapor content were investigated.In the orthogonal experiment of factors such as the bed height,the order of CO2 adsorption by each factor is:CO2 concentration>carbonation temperature>flue gas flow>water vapor content>bed height.Within the range of experimentally selected factors,the optimal experimental conditions for carbon dioxide fixation by steel slag are:carbonation temperature is 650?,CO2 concentration is 10%,flue gas flow is 1 L/min,water vapor content is 10%and bed Height is 14 cm.In order to increase the carbon sequestration efficiency for the compounding method,carbon slag was mixed with different proportions of slaked lime and alumina to prepare a carbon-fixing adsorbent,and CO2 adsorption experiment was performed in fluidized bed reactor.The results show that after adding slaked lime to steel slag,the pH value of the carbonation system is significantly increased,the carbonation reaction proceeds rapidly in the forward reaction direction,and the CaO of the carbon fixation active component in steel slag is fully reacted,and the carbon fixation efficien,cy is relatively pure.Get improved.When the proportion of steel slag and slaked lime is 1:1 in the compounding system,the carbon fixation efficiency reaches 27.81%.