Preparation of aragonite from calcium carbonate via wet carbonation to improve properties of steel slag building materials

Smelting in steel mills emitted large amounts of CO2 and produced the waste product steel slag (SS). Therefore, the use of SS to fix CO2 and produce value-added products could treat waste with waste and promote the effective use of resources. In this study, aragonite-type calcium carbonate was prepared by wet carbonation of SS, and the aragonite-rich SS (ASS) was pressed and moulded in the raw material of SS for semi-dry carbonation to obtain SS products. Through a series of experiments, the optimal conditions for the modulation and the formation mechanism of aragonite whiskers were investigated, and the effects of aragonite as a crystal seed on the properties and the degree of carbonation of SS products were also explored. In this experiment, the carbonation products were characterised microscopically by XRD, TGA, FT-IR and SEM, and the strength was tested by press machine. The results showed that aragonite phase was produced by wet carbonation of SS suspension containing 0.1 M/L MgCl2 at 120 °C for 2 h. The compressive strength, flexural strength, and secondary carbonation degree of the prepared SS products were increased when 5 % ASS was added. © 2024