Construction of "Kakuro" as an Improved Furnace of "Tatara" for Pig Iron Making

Abstract

The Japanese traditional ironmaking "Tatara" was the unique process using iron sand and charcoal in the world. In 1923, "Tatara" was commercially stopped to operate because of cheaper price of imported pig iron and steel than domestic products. In the middle of Meiji period, Mr. Fuyukiti Obana and Mr. Masateru Kuroda improved the Tatara furnace and constructed "Kakuro" furnace to use waste slag for refining of pig iron and/or iron sand as iron resources. The Tatara furnace was a box type furnace with 1.2 m in height and reconstructed every operation. Three original types of "Kakuro" were developed. The Kakuro furnace in the Ueno works was the same hearth construction with V-type ditch as Tatara furnace and had the high wall of firebricks of about 3 m in height in order to improve the productivity. The 8 tuyers in this furnace were arranged in parallel with the ditch and the higher temperature zone was produced by soft blow. This type of furnace was suitable for using powder iron ore such as iron sand and developed in the Izumo provinces. The Kakuro in the Ochiai works had the square hearth of about 1 m² with 3 tuyers and high shaft and chimney of firebricks of about 8 m in height. The "Maruro" in the Kadohira works had the round hearth with 4 tuyers and high shaft of firebricks of about 10 m in height. The latter Kakuro and Maruro used lumps of refining slag as an iron resource with hard blow.