Study on Characteristics of Steel Slag for CO₂ Capture

Abstract

Steel slag is a kind of alkaline mixture and considered to be a potential CO2 adsorbent. In this work, the CO2-trapping characteristics of two types of steel slag, basic oxygen furnace (BOF) steel slag and electric arc furnace (EAF) steel slag, were experimentally investigated. Generally, the higher the temperature, the larger the Ca use of slag. However, the Ca use at 550 °C would be lower than that at 500 °C for a certain CO2 concentration. The CO2 concentration also has an effect on the Ca use. At higher temperatures, a larger Ca use appears at a lower CO2 concentration (<10%) or higher CO2 concentration (>75%). As the CO2 concentration decreases, the reaction rate of carbonization increases, regardless of the kind of slag used. With regard to the type of steel slag, EAF steel slag is better than BOF steel slag in reactivity and Ca use. All of the results indicate that the carbonation reaction of steel slag is controlled by not only the reaction kinetics but also the diffusion of the reactive gas CO2. Steel slag has a capacity to capture and permanently sequester CO2. However, what is more important is that it can be used in different flue gases, where the CO2 concentration is typically lower (<20%) or fairly higher (>75%). This provides the steel slag a wide application market.

Direct Gas–Solid Carbonation Kinetics of Steel Slag and the Contribution to In situ Sequestration of Flue Gas CO2 in Steel‐Making Plants

“…Generally, about 2.0 t of CO 2 are emitted and 0.13-0.2 t of steel slag are produced per ton of steel produced. [5] In China, more than one billion tons of CO 2 have been emitted into the atmosphere from the iron and steel industry annually since 2006, which accounts for nearly 15 % of the country's total annual CO 2 emissions and 3-4 % of the total global annual CO 2 emissions. [6,7] According to IISI (International Iron and Steel Institute) and IEA (International Energy Agency) estimations, [8] China is responsible for nearly half of the total iron and steel industry CO 2 emissions in the world.…”

Use of steel slag for CO2 capture under realistic calcium-looping conditions

“…47 Thus, steel slag (with a high Ca content) has recently attracted some interest as a possible CaO precursor due to its abundance, low cost and non-toxicity for in situ CO 2 capture in the steel industry by means of the CaL process. 48,49 Steel slag is obtained as a byproduct from the separation of the molten steel from impurities using limestone in the steelmaking furnaces and currently is of value for use in agriculture, as asphalt aggregate and in construction. Nevertheless, considerable amounts (around 24% in EU) are treated as waste for landll or stored onsite at the steelmaking works.…”

Emerging Energy-efficiency and Carbon Dioxide Emissions-reduction Technologies for the Iron and Steel Industry

“…As the CO 2 concentration decreases, the carbonization reaction rate increases, regardless of the kind of slag used. With regard to the type of steel slag, EAF steel slag has better reactivity and Ca use than BOF steel slag (Yu and Wang 2011).…”