Closed-circulating CO2 sequestration process evaluation utilizing wastes in steelmaking plant

Utilization of steelmaking slag for carbon capture and storage with flue gas

Carbon capture and storage is a necessary action for the reduction of CO₂ emissions, and thereby mitigation of climate change and its impacts. Especially, in India, with its growing fuel needs and very little attention paid towards carbon capture and storage, mineral carbonation technology is a suitable option as it is cost-effective and could be retrofitted to existing plants that emit CO₂. Given the development of carbon capture and storage technology, this study attempts direct mineral carbonation of steelmaking slag with flue gas. Response surface methodology was employed to design gas-solid and slurry phase aqueous carbonation experiments. A maximum reduction of about 36.1% was achieved through aqueous carbonation at 61.1 °C, 46.24 bar, and a liquid-to-solid ratio of 14.5, corresponding to a sequestration capacity of 127.4 g of CO₂/kg of slag. The temperature was found to be the most vital parameter in both the aqueous and gas-solid carbonation processes. Regression models used to study the carbonation process were found to be statistically significant. The carbonated slag consisted of mineral phases, namely, calcite and dolomite. The results demonstrated the sequestration potential of Indian steelmaking slag with flue gas. Carbonation of steelmaking slag with flue gas poses to be a promising option for the development of carbon capture and storage technology in the country.

Research status and future challenge for CO2 sequestration by mineral carbonation strategy using iron and steel slag

Mineral carbonation can simultaneously realize the effective treatment of CO₂ and iron and steel slag; thus, it is of great significance for the low carbon and sustainable development of iron and steel industry. In this article, the researches of mineral carbonation process using iron and steel slag as feedstock are reviewed, and the carbonation reaction mechanism and the parameters affecting the reaction rate and carbonation degree are analyzed. Furthermore, the effect of different enforcement approaches, such as ultrasonic enhancement, mixed calcination, microbial enhancement, and cyclic coprocessing on mineral carbonation reaction, is introduced. The additional effects of mineral carbonation, such as solving the problem of poor volume stability of steel slag, weakening the leaching of heavy metal ions, and reducing the pH of the leachate, are also illustrated. Moreover, issues related to mineral carbonation technology that should be emphasized upon soon, such as the production of valuable products, use of industrial wastewater, aqueous phase recycling use, multiparameter coupling analysis, and research on the properties of carbonation residues, are also discussed, which contribute some perspectives to the future development of mineral carbonation of iron and steel slag.

Kinetics model adaptability analysis of CO2 sequestration process utilizing steelmaking slag and cold-rolling wastewater

Better adaptive kinetics model for CO₂ sequestration utilizing wastes in steelmaking plant has a big significance for establishing green out-circulating network system. This work investigated the effect of temperature, L/S ratio and cold-rolling wastewater concentration on carbonation degree in basic oxygen furnace slag and CRW carbonation process, then their kinetics was discussed by surface coverage model and shrinking core model, respectively, in order to evaluate their adaptability and accuracy. Furthermore, CO₂ sequestration intensifying factor was originally proposed for considering the carbonation depth, through comparing diffusion coefficient of CO₂ between water carbonation and wastewater carbonation. The results showed that carbonation conversion increased as temperature and CRW concentration increased except for L/S ratio, and the maximum carbonation could reach 41.499 ± 1.240%. Because higher prediction error existed in surface coverage model, the shrinking core model had a better adaptability and accuracy for analyzing carbonation process in autoclave. Meanwhile, the CO₂ sequestration intensifying factor was 1.6 times as big as carbonation process in distilled water as a result of D_CO2 value. CO₂ sequestration reaction in our work was controlled by calcium diffused because of D_CO2 (0.700-0.976 × 10^-4 cm² s^-1) and D_Ca (0.935-1.149 × 10^-5 cm² s^-1). The results above will be helpful for us to better comprehend the reaction kinetics at micro-scale, when the idea of triple wastes self-circulation system network will be established to industrial application.

Utilization of Gaseous Carbon Dioxide and Industrial Ca-Rich Waste for Calcium Carbonate Precipitation: A Review

Technologies for the management of various types of waste and the production of useful products from them are currently widely studied. Both carbon dioxide and calcium-rich waste from various production processes are problematic wastes that can be used to produce calcium carbonate. Therefore, the purpose of this paper is to provide an overview about the state of the development of processes that use these two wastes to obtain a valuable CaCO3 powder. The paper reviews the current research on the use of post-distillation liquid from the Solvay process, steelmaking slag, concrete, cement, and gypsum waste as well as some others industrial Ca-rich waste streams in the calcium carbonate precipitation process via carbonation route. This work is an attempt to collect the available information on the possibility of influencing the characteristics of the obtained calcium carbonate. It also indicates the possible limitations and implementation problems of the proposed technologies.