Solid State Nitriding of High and Medium Carbon Ferromanganese

Abstract

The ferromanganese industry suffers from the accumulation of great amounts of high and medium carbon ferromanganese fines resulting during crushing of the alloy. These fines represent a problem due to the difficulty of their marketing with the consequence of a bad economic effect on the production process. In this study, bench and pilot plant experiments were carried out to investigate the process of nitriding of high carbon and medium carbon ferromanganese fines (−3 mm) in the solid state condition at a temperature range of 750-1050 °C using different pressures of nitrogen gas.A nitrogen content of 0.37 to 1.32% (by weight) was obtained when nitriding high carbon ferromanganese. Nitriding of medium carbon ferromanganese has successfully produced ferromanganese alloy with 2.2% carbon and 6.2% nitrogen at a pressure of 10 bar nitrogen mixed with 2 bar hydrogen pressure at 950 °C. It was also found that the duration of the nitriding process has a great effect on the nitrogen pickup by the ferroalloy. The maximum content of the nitrogen absorbed was found to depend on the temperature and pressure conditions. The pilot plant results were found to coincide with bench scale ones.