Hamad Amer Alsaiari

Iron Calcium Carbonate: Precipitation Interaction

Iron (ll)-Calcium Carbonate: Precipitation Interaction By Hamad a. Alsaiari Little attention has been paid to the reaction of mixed calcium-iron carbonate in solutions in comparison with the reaction of other solids such as calcium carbonate, calcium sulfate and barium sulfate. As a result, little information is presently available about the interaction and precipitation of iron carbonate and mixed calcium/iron. It is known that iron carbonate precipitation kinetics is sensitive to temperature. At high temperature (65 °C), a sharp drop in iron concentration was observed during the first minutes in a solution devoid of calcium. And the drop was gradual at 55 °C. However, adding calcium to the solution under the same conditions had a great influence in reducing the drop in iron concentration. The apparent increase in the solubility of ferrous iron was proportional to the concentration of calcium present in the solution. In addition, presence of calcium in solution also reduced the effect of temperature on siderite precipitation. On the other hand, the presence of iron did not show significant impact in the solubility of calcium. The cumulative and instantaneous molar ratio of ferrous iron to calcium in the precipitated solid was found to be varied based on the molar ratio of calcium and iron ions in the inflow stream and the amount of siderite that initially precipitated. The relation between the molar ratio of the calcium to iron in solid and in influent was calculated. It found to be 2.39.