The Research Of CO₂Carbonation Fixation By Using Steel Plant Slag

Greenhouse effect causing climate warmer made the global emissions reduction facing hugepressure, it is very necessary to carry out the study of CO₂capture, transport and fixationtechniques. Iron and steel industry is a major CO₂emissions source as well as discharges a lot ofsolid waste in China. There are plenty of advantages to use iron and steel smelting slagcarbonated with CO₂, such as high waste slag output, low price of raw materials, close to theCO₂emissions sources and no secondary pollution generated. Therefore, CO₂carbonationsequestration by using steel plant slag is a kind of effective way to long-term store CO₂, it is ofsignificant to reduce CO₂emissions and handing of solid waste. This paper expands thefollowing research.Firstly, through the analysis and calculation of thermodynamics by the Factsage softwarefind out the dry and wet process CO₂fixation feasibility of reaction from the six main phase iscontaining calcium magnesium （such as C2S（2CaO·SiO2）, MgSiO₃and CaSiO₃, C₃S（3CaO·SiO2）,CaO, MgO, etc） in different leaching agent （acetic acid, ammonium salt and water）. Secondly,for the wet carbonation the reaction process explore slag, reaction time, temperature, solid-liquidratio, leaching agent and its concentration, leaching rate of solution Ca²⁺and other impurities inion relations, proves the wet carbonation process Ca²⁺leacning reaction kinetics mechanism andseeking the best leaching reaction conditions. Finally, explore the wet carbonation processCaCO₃precipitation reaction process, reaction time, temperature, CO₂concentration and flowrate, stirring speed, type and concentration of the precipitation, seeking the best CaCO₃precipitation reaction conditions.The experimental results show that the slag containing calcium magnesium phase is in the273K to1073K temperature range, the dry carbonation reaction process are exothermic, and theslag under normal temperature and pressure containing calcium magnesium carbonate of thereaction are spontaneous. Using water, acetic acid and ammonium chloride as leaching agent in273K-573K temperature range, the leaching effect of acetic acid is the best, the ammoniumchloride followed by it and pure water is the worst. Containing Ca²⁺, Mg²⁺of the leachingsolution in room temperature and atmospheric pressure most can’t spontaneous, it needappropriate alkalization.Leaching reaction occurs mainly in the first60min, extend the leaching time on Ca leachingrate has little effect. The leaching effect of calcium in the slag, acid is better than the acid salt,acid salt is better than pure water, LF slag is better than converter steel slag, converter steel slagis better than KR slag. Increase the leaching agent concentration, improve leaching temperatureand solid-liquid ratio and select more acidic leaching agents are coincidence to leaching of thecalcium. Study on leaching kinetic shows that reaction of the leaching coincidence shrinking core model, and metallurgical slag leaching rate greater impact on particle size. The reaction ofcarbonate process is fast, under the appropriate amount of alkalinity the yield of Ca is easy toachieve perfection, increasing the reaction temperature, extend the time of ventilation, increasethe proportion of CO₂/N2mixing ratio and improve the gas flow can help to improve the yield ofCa.