EXTRACTION OF MAGNESIUM METAL FROM FERRONICKEL SLAG WITH ALUMINOTHERMIC UNDER VACUUM CONDITION USING VERTICAL FURNACE

• Main Author: Sulton Fahrudin, Muchamad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/64831
• Institution: Institut Teknologi Bandung

Production of ferronickel using Rotary Kiln – Electric Furnace (RKEF) technology continues to increase in line with the demand for stainless steel. Increasing ferronickel production will increase the slag amount. Production of 1 tonne of ferronickel produces slag about 14 tonnes. The ferronickel slag mainly consists of SiO2, MgO, and FeO, with the main mineral phases being forsterite (Mg2SiO4), enstatite (MgSiO3), and diopside (CaMgSi2O6). The MgO content in ferronickel slag produced by the RKEF line is above 25%. Therefore, ferronickel slag can be an alternative source of magnesium metal. FeSi as a reductor for magnesium production is still imported while Al can be produced domestically and alternative sources of Al are available such as Al dross and Al from scrap. In this study, the extraction of magnesium metal from ferronickel slag is carried out using a reductor consisting of aluminum and aluminum dross with the addition of CaO and CaF2 as additives. A series of experiments on the extraction of magnesium from ferronickel slag have been carried out to study the effect of adding CaO additives, the proportion of reductor from aluminum and aluminum dross, and reduction temperature on the extraction of magnesium metal from ferronickel slag. The basis used in each experiment was a mass of 25 grams of ferronickel slag. Experiments were carried out by varying the CaO, namely 0%, 40%, and 80%, varying the proportion of reductor at Al 40%, Al dross 40%, and the combination of Al and Al dross 20% each, and variations in the reduction temperature at 900 °C and 1200 °C. The reduction process was carried out using a vertical tube furnace under vacuum (10 Pa of pressure) and held for 4 hours. The results of the reduction and residue were then analyzed using X-ray Diffraction (XRD), X-ray Fluorescence (XRF), and Scanning Electron Microscope – Energy Dispersive Spectroscopy (SEM-EDS). The results show that the weight loss of the sample is in the range of 5 – 11% with the largest weight loss obtained in the P3 experiment (Al 40%, CaO 80%, CaF2 3%, 1200 °C, 10 Pa) with a value of 11.55%. The extraction percentage obtained with the addition of CaO 0%, 40%, and 80%, respectively, are 70.44%, 92.37%, and 56.63%, while the percent extraction at temperatures of 900 °C and 1200 °C respectively are 83.18% and 92.37%. Meanwhile, the aluminum reductor produces a better extraction percentage than aluminum dross with the values obtained for the reductor Al dross 40%, Al 20% - Al dross 20%, and Al 40% respectively are 83.41%, 77.90%, and 92.37%. The largest magnesium extraction percentage is obtained in the P2 experiment (Al 40%, CaO 40%, CaF2 3%, 1200 °C, 10 Pa) with a magnesium extraction percentage of 92.37%.