Study on Efficient Use of High‐Manganese Pig Iron

Abstract

The smelting process of high‐manganese pig iron is studied to determine ways to efficiently utilize the by‐product of manganese‐rich slag. This process consists of two stages: 1) demanganese and carbon retention and 2) decarbonization and dephosphorization. In the first stage, oxygen is supplied at 0.5–2.0 Nm3 t−1 min−1. The temperature is controlled between 1300 and 1400 °C by adding iron ore to the molten bath. Ultimately, high‐manganese slag, which contains more than 50% manganese oxide and semisteel with 3.2% carbon, is produced. In the second stage, oxygen is supplied at 2.0−5.0 Nm3 t−1 min−1 and slag‐forming materials are added to the molten bath for the dephosphorization and desulfurization of the hot metal. Consequently, the iron oxide, manganese oxide, and silicon oxide contents of the high‐manganese slag and the carbon, manganese, phosphorus, and sulfur contents of the semisteel are 10.8–15.3%, 70–77%, and 3–7%, and 3.2–4.2%, 0.3–1.0%, 0.12–0.22%, and 0.01–0.024%, respectively. The main mineral phases of high‐manganese slag, 2MnO·SiO2 and FeO·MnO·SiO2, are suitable for the preparation of high‐carbon ferromanganese raw materials. After further smelting, clean molten steel containing 0.03−0.08%, 0.08−0.20%, 0.005−0.02%, and 0.01−0.024% carbon, manganese, phosphorus, and sulfur, respectively, is obtained.