After the leaching of the Ca 2+ and Mg 2+ ions from the solutions of anhydrite, clear solutions are filtered and used for the next step of precipitation in the carbon dioxide sequestration process at the partner university, Otto-von-Guericke University, Magdeburg. Germany), was added continuously at 2.5 ml min -1 to 300 ml anhydrite extract at 𝑆𝑡 = 1.0. While the NaOH solution was added, pH and Ca 2+ ion concentration were measured respectively using the pH Sensor InLab Expert and DX240-Ca ion selective electrode (ISE), both Mettler Toledo make. The ISE sensor is only used to understand dynamic changes in concentration during the experiment. IC measurements are more accurate, but the analysis takes longer and there is a delay for control. The CO2 needed for the carbonation was supplied to the solution by bubbling the CO2 gas (99.5 % pure), from Linde GmbH (Pullach, Germany), at a constant rate during the pH shift process. To extract pure carbonates selectively through the pH swing process, first, CaCO3 was precipitated since the solubility of CaCO3 is much lower than that of MgCO3. The pH of the anhydrite extracted solution, which is initially at a very low pH, is increased until pH 8 and maintained at this pH by the continuous supply of CO2 and NaOH until the Ca 2+ concentration (measured using the Ca ISE) in the solution is almost zero. After extracting the precipitated CaCO3, the pH of the solution was further increased to around pH 10 where the hydrated forms of MgCO3 would precipitate. However, since the concentration of Mg 2+ was too low in the anhydrite solution, no carbonates of magnesium could be precipitated.