Chemical grade limestone is important to the process as it is the primary raw material which helps remove impurities from the iron ore and produces a slag with low melting point and a high fluidity. Consistency of the chemical grade limestone for chemistry and sizing is critical for efficient blast furnace operations and cost control.
Limestone will react with the temperature in the blast furnace as it continues down the furnace to react with sulfur from the iron and produce a slag with the silica formed from the iron ore. The first reaction involved is as follows: CaCO3 = CaO + CO2 The CaO is used to remove the sulfur and react with the silica to produce a fluid slag at the bottom of the furnace.'
Carmeuse’s chemical grade limestone (click here) has high, specific levels of Calcium Oxide (Cao), Magnesium Oxide (MgO), or both.
Additionally, chemical grade limestone has a high level of purity in that it contains very low levels of residuals typically found in limestone composites such as, silica, clay, organic matter, iron oxide, and siliceous skeletal fragments.
The optimum chemistry and purity of chemical grade limestone makes it ideal for flue gas desulphurization and steel making, both of which require exacting specifications.