Carbonation And Utilization Of Basic Oxygen Furnace Slag Coupled With Concentrated Water From Electrodeionization

Among all kinds of greenhouse gas can be controlled by humanbings,CO2 has the greatest impact on global surface warming.Mineral carbonation is the only known form of permanent carbon storage.Basic oxygen furnace slag(BOFS)is a kind of byproduct of the steelmaking process which contained unstable component limits its utilization as construction materials.However,those constituents are favored by carbon storage.Concentrated water from electrodeionization(CW-EDI)is the effluent generated in electrodeionization process with high concentration of Na+ and Ca2+ and has little reuse routes.CW-EID was introduced in the BOFS c.arbon storage process for the first time in this study.The leaching behaviors of BOFS in CW-EDI and the carbonation of BOFS and CW-EDI via a rotating packed bed reactor were explored.The feasibility of CW-EDI treatment through the carbonation process and the performence of cement with BOFS as supplementary cementitious materials were also studied.The conclusions showed as follows:(1)The leaching process of BOFS in CW-EDI finished in 10 min.The kinetics of Ca2+ and OH' in CW-EDI fit the first order mass-balance model well.A high level of Ca2+ and pH hindered the leaching of calcium from BOFS.The fastest calcium leaching rate,1.797 min-1,appeared at pH 7 with 803 mg L-1 Ca2+ in the initial CW-EDI.No Na+leached from BOFS during the leaching process.Furthermore,Na+ was adsorbed by BOFS which reached equilibrium in a short time in sodium rich liquid.(2)Reaction time,liquid to solid ratio,rotation speed of the reactor and slurry flow rate influenced the carbonation much while gas flow rate had little effect.The surface coverage model expressed the carbonation kinetics well.The max achievable carboantion conversion was 60.9%.pH and sodium levels of CW-EDI both remained the same after a descence during the carbonation while calcium level decreased with a following rise.(3)The autoclave expasion ratio of OPC could be reduced by the addition of BOFS and the carbonation process stabilized the BOFS.OPC with 10%and 15%of fresh BOFS or 10%of carbonated BOFS had a better compressive property than pure OPC.In the view of economy and environmental benefit,as well as the performance,the suggested substitution ratios for fresh and carbonated BOFS were 15%and 10%,respectively.