Study on the Iron Production Process through the Analysis of By-Products Found at Jiǔdiàn Iron Production Site, China

$Ji{\check{u}}di{\grave{a}}n$ iron production site in China is a relic smelting site, which in the past produced pig iron. In this study, scientific analysis of the smelting furnace and collected slag was conducted to reveal some aspects of the ancient Chinese smelting technique. A 3D model of the smelting furnace showed a narrow lower part and an upper section which increased in diameter upwards. Although the smelting furnace relic does not include the upper part and its complete shape cannot be predicted, the remaining part suggests that the furnace had a larger diameter in the central part compared to the upper and lower parts. Most of the collected slag was completely vitrified. Long prismatic fayalite was observed in the matrix of some samples. The iron particles contained phosphorus, which could not be discharged during smelting work. In addition, as the $CaO/SiO_2$ ratio was 0.42 or lower in the results of the content analysis, no CaO slag former had been added. However, the ratio of $CaO/SiO_2$ to $Al_2O_3/SiO_2$ did not have a constant trend. This needs to be investigated in a further study.