This is the most modem process for the manufacture of steel and is based on the regenerative system of heat economy. The charge consisting of a mixture of pig iron, scrap iron and hematite ore free from carbon is taken into the trough or hearth of the furnace. The heath of the furnace is lined either with dolomite or magnesia or silica depending upon the nature of the impurities present. The ehargc is heated by means of the flame obtained by burning fuel gases. The hot ,waste gases from the furnace are allowed to escape through the fire-bricks check-work “C” and “D” who absorb the heat of the escaping gases.
A small quantity of the charge is drawn out from time to time to analyses the carbon content. The carbon content of steel is adjusted by adding the appropriate amount of spiegeleisn. The steel obtained by open-hearth process is used for making rail wheels, axles, springs, guns, girders and ships.