Phosphorus in Steelmaking Processes

Abstract

This chapter examines the role of iron ore phosphorus in the development of steelmaking. The prosperity of steelmaking nations strongly depended on how they strategically dealt with iron ores with various phosphorus contents. At the beginning of steelmaking, the ore’s phosphorus content was immaterial. However, as the quality of steel improved, the effect of phosphorus became obvious. In Europe, iron ores with higher and lower phosphorus content were minable, prompting the development of the Thomas and Bessemer steelmaking processes, respectively. At the dawn of the Industrial Revolution, the main steel producer was the UK using the Bessemer process, but then it shifted to Germany adopting the Thomas process, followed by the USA, which used both open-hearth furnaces for scrap steels and the Thomas process until the mid-twentieth century. In these transitions, Germany found that slag, a steelmaking by-product with higher phosphorus content, could be used as phosphate fertilizer. Japan invented a phosphorus-oriented steelmaking process charging phosphate ore in addition to iron ore; in this process, slag with higher phosphorus was used as fertilizer. After World War II, Japan developed a highly efficient iron ore transpiration system using bulk carrier, and the introduction of the so-called Linz-Donawitz converter process with oxygen gas strongly promoted Japan to the steelmaking mainstream up to the present; most of their products contain extremely low phosphorus. Thus, innovative changes in steelmaking can be explained from the standpoint of the iron ore phosphorus content. From these summaries, future strategies for steel industries are discussed.