Carbon dioxide capture by steel-making residues in a fluidized bed reactor
Global warming is one of the most challenging problems facing societies these days, and it is known to be caused by the increasing emissions of Green House Gases (GHG's), mainly CO2, from various human activities. To solve such problem, or at least minimize its effects, several actions have been considered. One of these actions is carbon capture, which has many different options and techniques. This research focuses on the capture of CO2 through reactions with steel-making residues, an alkaline solid by-product of the steel-making process. The aim is to sequester CO2 and form carbonates, which are chemically more stable form of the solid waste. The reaction was carried out in a fluidized-bed reactor that provided good interaction between CO2 and the solid residue with low operational cost. Minitab facilities were used to design a set of experiments and get a statistical model that describes different behaviors of responses such: CO2 efficiency, CO2 capture percentage, T.D.S. and leachability. These responses were governed by parameters such as: flow rate of CO2 gas, particle size, initial amount and type of the residue, in addition to the moisture bed percentage. The effluent gas was analyzed for CO2 and the solid product was characterized using TGA, XRD, SEM and ICP. Three types of solid residues were used in the study: Cyclone Silo Dust, LF Slag and Bag House Dust. The maximum capture percentage was observed when using Bag House Dust (BHD), with 0.2 kg- CO2/ kg residue, based on the Ca-content, at a gas flow rate ratio to the minimum fluidization velocity (Us/Umf) of 1.5, a bed mass of 1.5 kg, an average particle size of 150 μm, and a bed moisture content of 3%.