Steelmaking Mechanisms for a Modified Tatara Furnace

Abstract

Tatara was used to be a traditional process to produce solid steel, so called "Kera", and/or liquid pig iron, so called "Zuku", from iron sand and charcoal using the box type furnace with blowing cold air intermittently. A modified Tatara furnace has been examined on the production mechanisms of "Kera". Temeratures and oxygen partial pressures in the furnace were measured by means of thermocouples and oxygen sensors with solid electrolyte of zirconia. Iron sand and a piece of "Kera" produced in the bottom of furnace were sampled and analyzed chemically or by a electron probe micro analyser. Iron sand is reduced above tuyere and absorbs carbon on fired charcoals in front of the tuyere at about 1350°C. Many small balls of liquid steel with different carbon content were found in molten slag pool of FeO-saturated silica, so-called "Noro", and cohere each other to grow into a bloom. The characteristics of Tatara steelmaking process are low temperature for carbon absorption of steel at about 1350°C, high oxygen potential in the molten slag of FeO-saturated silica and hypo-eutectic carbon content in steel.