Charging the Cupola:

While the coke bed has thoroughly ignited alternate layers of pig iron coke & flux are charged from the charging door. Appropriate scrap is also added up with the pig iron to control the chemical composition of the iron formed. The thickness of the layers is kept around 150-200 mm. The reason of adding flux is to remove the impurities and so refine the metal to defend the metal from oxidation and to render to slag more fluid for simple disposal. In addition limestone fluorspar and soda ash also sometimes utilized as fluxing materials. The quantity of limestone, needed might be 30-40 kg per ton of iron melted or 25% by weight of the coke charged.