Synthesis of calcium carbonate powder from air-cooled blast furnace slag under pressurized CO2 atmosphere

다국어 초록 (Multilingual Abstract)

A process to produce pure calcite-type calcium carbonate by the carbonation of air-cooled blast furnace slag (BFS), which is a waste material and which has been utilized in limited applications, is reported here. The process is composed of two reactions. First, calcium ions are extracted from an air-cooled BFS slurry under pressurized gaseous CO2 (1 to 5 MPa) at 273 K, at which the extracted calcium ions and calcium carbonate formed during the extraction process are dissolved in the solution due to the high solubility of the calcium carbonate under the high pressure of CO2. The second reaction is the precipitation of pure calcite-type calcium carbonate at atmospheric pressure at the same temperature after the removal of the solid residue remaining after the extraction process. Gaseous CO2 was fed at atmospheric pressure to increase the precipitation ratio of calcium carbonate by the carbonation of the unreacted calcium ions in the solution. In this study,the influences of the following parameters on the extraction of calcium ions at 293K were investigated experimentally:the initial weight ratio of air-cooled BFS to water, the CO2 pressure, and the extraction time. According to our results, the extraction of calcium ions is not proportionally improved by increasing the aforementioned experimental parameters.

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