Limestone and dolomite flux and their use in iron and steel plant...

Limestone and dolomite flux and their use in iron and steel plant Limestone is a naturally occurring mineral. The term limestone is applied to any calcareous sedimentary rock consisting essentially of carbonates.  The ore is widely available geographically all over the world. Earth’s crust contains more than 4 % of calcium carbonate. Limestone is basically calcite which is theoretically composed of exclusively calcium carbonate (CaCO3). When limestone contains a certain portion of magnesium, it is called dolomite or dolomitic limestone (CaCO3.MgCO3). Dolomite theoretically contains CaCO3 54.35 % and MgCO3 45.65 % or CaO 30.4 %, MgO 21.9 % and CO2 47.7 %. However, in nature, dolomite is not available in this exact proportion. Hence generally the rock containing 40-45 % MgCO3 is usually called dolomite. When MgCO3 is less than 40 % but more than 20 % then the limestone is called dolomitic limestone. The chemical composition of limestone and dolomite varies greatly from region to region as well as between different deposits in the same region. Therefore, the end product from each natural deposit is different.  Typically limestone and dolomite are composed of calcium carbonate (CaCO3), magnesium carbonate (MgCO3), silica (SiO2), alumina (Al2O3), iron (Fe), sulphur (S) and other trace elements. These minerals are shown in Fig 1 Fig 1 Limestone and dolomite The limestone from the various deposits differs in physical chemical properties and can be classified according to their chemical composition, texture and geological formation. Limestones from different sources differ considerably in chemical compositions and physical structures. The chemical reactivity of various limestones also shows a large variation due to the difference in crystalline structure and the nature of impurities such as silica, alumina and iron etc. The varying properties of the limestone have a big influence on the processing method....