The TG/DTG curve obtained for egg shell calcium carbonate is seen in Figure 1b. The curve showed thermal stability up to 630 °C with a mass loss of Dm = 2.6% referring to volatile material. The thermal decomposition process occurs at the temperature range from 636 to 795 °C with mass loss Dm = 42.5%, which corresponds to carbon dioxide release, in a single step, in a defined way.