As mixing time increase, the compounds and ions have enough time to soluble in solution resulted in the pH and conductivity increase. However, one can observe that the conductivity of the solution deceases slightly after 30 min mixing time, and then remains almost constant. This reduction in conductivity value could be related to the precipitation of some compounds such as CaCO3 [14] [18] [19]. The presence of CO2 available in surrounding atmosphere (the vessel was open) dissolves in the slurry solution, resulting in the CO2 dissolution which can reacts with Ca ions in the solution to form calcium carbonate.